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Electronics, Volume 9, Issue 2 (February 2020) – 179 articles

Cover Story (view full-size image): Smart devices are present in every aspect of everyday life from smartphones, which are now like mini-computers, to systems for monitoring sleep or fatigue and specific sensors for the recording of vital parameters. A particular use of the latter is health monitoring. Through the use of such devices, several vital parameters can be acquired and automatically monitored, even remotely. VITAL-ECG is a smart device designed to monitor the most important vital parameters with a one-touch device, anywhere, and at low cost. It is a wearable device that, coupled with a mobile app, can track bio-parameters including electrocardiogram, SpO2, skin temperature, and physical activity of the patient. View this paper
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Open AccessEditor’s ChoiceArticle
EARL—Embodied Agent-Based Robot Control Systems Modelling Language
Electronics 2020, 9(2), 379; https://doi.org/10.3390/electronics9020379 - 24 Feb 2020
Cited by 3 | Viewed by 1330
Abstract
The paper presents the Embodied Agent-based Robot control system modelling Language (EARL). EARL follows a Model-Driven Software Development approach (MDSD), which facilitates robot control system development. It is based on a mathematical method of robot controller specification, employing the concept of an Embodied [...] Read more.
The paper presents the Embodied Agent-based Robot control system modelling Language (EARL). EARL follows a Model-Driven Software Development approach (MDSD), which facilitates robot control system development. It is based on a mathematical method of robot controller specification, employing the concept of an Embodied Agent, and a graphical modelling language: System Modelling Language (SysML). It combines the ease of use of SysML with the precision of mathematical specification of certain aspects of the designed system. It makes the whole system specification effective, from the point of view of the time needed to create it, conciseness of the specification and the possibility of its analysis. By using EARL it is possible to specify systems both with fixed and variable structure. This was achieved by introducing a generalised system model and presenting particular structures of the system in terms of modelling block configurations adapted by using instances. FABRIC framework was created to support the implementation of EARL-based controllers. EARL is compatible with component based robotic middlewares (e.g., ROS and Orocos). Full article
(This article belongs to the Section Systems & Control Engineering)
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Open AccessArticle
A Novel Changing Athlete Body Real-Time Visual Tracking Algorithm Based on Distractor-Aware SiamRPN and HOG-SVM
Electronics 2020, 9(2), 378; https://doi.org/10.3390/electronics9020378 - 24 Feb 2020
Cited by 2 | Viewed by 994
Abstract
Athlete detection in sports videos is a challenging task due to the dynamic and cluttered background. Distractor-aware SiamRPN (DaSiamRPN) has a simple network structure and can be utilized to perform long-term tracking of large data sets. However, similarly to the Siamese network, the [...] Read more.
Athlete detection in sports videos is a challenging task due to the dynamic and cluttered background. Distractor-aware SiamRPN (DaSiamRPN) has a simple network structure and can be utilized to perform long-term tracking of large data sets. However, similarly to the Siamese network, the tracking results heavily rely on the given position in the initial frame. Hence, there is a lack of solutions for some complex tracking scenarios, such as running and changing of bodies of athletes, especially in the stage from squatting to standing to running. The Haar feature-based cascade classifier is involved to catch the key frame, representing the video frame of the most dramatic changes of the athletes. DaSiamRPN is implemented as the tracking method. In each frame after the key frame, a detection window is given based on the bounding box generated by the DaSiamRPN tracker. In the new detection window, a fusion method (HOG-SVM) combining features of Histograms of Oriented Gradients (HOG) and a linear Support-Vector Machine (SVM) is proposed for detecting the athlete, and the tracking results are updated in real-time by fusing the tracking results of DaSiamRPN and HOG-SVM. Our proposed method has reached a stable and accurate tracking effect in testing on men’s 100 m video sequences and has realized real-time operation. Full article
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Open AccessArticle
Unilateral Route Method to Estimate Practical Mutual Inductance for Multi-Coil WPT System
Electronics 2020, 9(2), 377; https://doi.org/10.3390/electronics9020377 - 24 Feb 2020
Viewed by 1030
Abstract
Multi-coil WPT systems require mutual inductance information between coils to increase the power transmission efficiency. However, in the high frequency (HF) bands such as 6.78 MHz and 13.56 MHz, the presence of surrounding coils changes the value of the mutual inductance between the [...] Read more.
Multi-coil WPT systems require mutual inductance information between coils to increase the power transmission efficiency. However, in the high frequency (HF) bands such as 6.78 MHz and 13.56 MHz, the presence of surrounding coils changes the value of the mutual inductance between the two coils due to the parasitic element effect of the coils. These parasitic effects make it harder to estimate the mutual inductance among three or more coils. In contrast to ideal mutual inductance, which has a constant value regardless of frequency and surrounding coils, we define the practical mutual inductance as the mutual inductance varied by parasitic elements. In this paper, a new method is presented to estimate the practical mutual inductance between multiple coils in the HF band. The proposed method simply configures the expression of practical mutual inductance formula because only one of two bilateral dependent voltage sources generated by mutual inductance is considered. For several coils placed along the same axis, the practical mutual inductances between coils were measured with respect to the distance between them to validate the proposed method. The practical mutual inductance obtained from the proposed method was consistent with the simulated and measured values in HF band. Full article
(This article belongs to the Special Issue Wireless Power/Data Transfer, Energy Harvesting System Design)
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Open AccessArticle
Analysis of Three-Phase Inverter Parallel Operation with Network-Based Control Having Strong Robustness and Wide Time-Scale Compatibility in Droop-Controlled AC Microgrid
Electronics 2020, 9(2), 376; https://doi.org/10.3390/electronics9020376 - 24 Feb 2020
Cited by 1 | Viewed by 893
Abstract
The system performances can be potentially enhanced for three-phase inverter parallel operation in droop-controlled AC microgrid by using network-based control, which also benefits for the extension of other control strategies in microgrids (MGs). It is highlighted that some negative factors such as network-induced [...] Read more.
The system performances can be potentially enhanced for three-phase inverter parallel operation in droop-controlled AC microgrid by using network-based control, which also benefits for the extension of other control strategies in microgrids (MGs). It is highlighted that some negative factors such as network-induced time-delays and data dropouts would possibly degrade the system operation. In this paper, the comprehensive analysis of network-based control strategy with strong robustness and wide time-scale compatibility is investigated in islanded mode of an AC microgrid with paralleled inverters. The theoretical evaluation towards time-delay and data dropouts is made and it is verified that its good power-sharing can be obtained under unsatisfactory communication conditions. It has been observed that the time-scale of network-based control can also be designed from several microseconds to milliseconds. Based on this idea, the communication integration of different layers of MGs in hierarchical structure would be realistic. Experimental results have verified the effectiveness of the network-based control strategy and analytical method. Full article
(This article belongs to the Special Issue Applications of Power Electronic Circuits and Systems for Future Grid)
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Open AccessArticle
A 1 GS/s 12-Bit Pipelined/SAR Hybrid ADC in 40 nm CMOS Technology
Electronics 2020, 9(2), 375; https://doi.org/10.3390/electronics9020375 - 23 Feb 2020
Cited by 3 | Viewed by 1096
Abstract
A 1 GS/s 12-bit pipelined/successive-approximation-register (pipelined/SAR) hybrid analog-to-digital converter (ADC) is presented in this paper, where the five most significant bits are resolved by two cascading 2.5-bit multiplying digital-to-analog converters, and the eight least significant bits are determined by a two-channel time-interleaved successive-approximation-register [...] Read more.
A 1 GS/s 12-bit pipelined/successive-approximation-register (pipelined/SAR) hybrid analog-to-digital converter (ADC) is presented in this paper, where the five most significant bits are resolved by two cascading 2.5-bit multiplying digital-to-analog converters, and the eight least significant bits are determined by a two-channel time-interleaved successive-approximation-register (TI-SAR) quantizer. An integrated input buffer and an operational amplifier with improved voltage efficiency at 1.8 V are adopted to achieve high-linearity stably in wide band for 1 GS/s. By designing a 500 MS/s 8-bit SAR quantizer at 1 V, the number of required interleaved channels is minimized to simplify the complexity and an adaptive power/ground is used to compensate the common-mode mismatch between the blocks in different power supply voltages. The offset and gain mismatches due to the TI-SAR quantizer are compensated by a calibration scheme based on virtually-interleaved channels. This ADC is fabricated in a 40 nm complementary metal-oxide-semiconductor (CMOS) technology, and it achieves a signal-to-noise-and-distortion ratio (SNDR) of 58.2 dB and a spurious free dynamic range (SFDR) of 72 dB with a 69 MHz input tone. When the input frequency increases to 1814 MHz in the fourth Nyquist zone, it can maintain an SNDR of 55.3 dB and an SFDR of 64 dB. The differential and integral nonlinearities are −0.94/+0.85 least significant bit (LSB) and −3.4/+3.9 LSB, respectively. The core ADC consumes 94 mW, occupies an active area of 0.47 mm × 0.25 mm. The Walden figure of merit reaches 0.14 pJ/step with a Nyquist input. Full article
(This article belongs to the Special Issue Analog/Digital Mixed Circuit and RF Transceiver Design)
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Open AccessFeature PaperArticle
Exploring Impact of Age and Gender on Sentiment Analysis Using Machine Learning
Electronics 2020, 9(2), 374; https://doi.org/10.3390/electronics9020374 - 22 Feb 2020
Cited by 7 | Viewed by 1732
Abstract
Sentiment analysis is a rapidly growing field of research due to the explosive growth in digital information. In the modern world of artificial intelligence, sentiment analysis is one of the essential tools to extract emotion information from massive data. Sentiment analysis is applied [...] Read more.
Sentiment analysis is a rapidly growing field of research due to the explosive growth in digital information. In the modern world of artificial intelligence, sentiment analysis is one of the essential tools to extract emotion information from massive data. Sentiment analysis is applied to a variety of user data from customer reviews to social network posts. To the best of our knowledge, there is less work on sentiment analysis based on the categorization of users by demographics. Demographics play an important role in deciding the marketing strategies for different products. In this study, we explore the impact of age and gender in sentiment analysis, as this can help e-commerce retailers to market their products based on specific demographics. The dataset is created by collecting reviews on books from Facebook users by asking them to answer a questionnaire containing questions about their preferences in books, along with their age groups and gender information. Next, the paper analyzes the segmented data for sentiments based on each age group and gender. Finally, sentiment analysis is done using different Machine Learning (ML) approaches including maximum entropy, support vector machine, convolutional neural network, and long short term memory to study the impact of age and gender on user reviews. Experiments have been conducted to identify new insights into the effect of age and gender for sentiment analysis. Full article
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Open AccessArticle
HEAP: A Holistic Error Assessment Framework for Multiple Approximations Using Probabilistic Graphical Models
Electronics 2020, 9(2), 373; https://doi.org/10.3390/electronics9020373 - 22 Feb 2020
Viewed by 810
Abstract
Approximate computing has been a good paradigm of energy-efficient accelerator design. Accurate and fast error estimation is critical for appropriate approximate techniques selection so that power saving (or performance improvement) can be maximized with acceptable output quality in approximate accelerators. In the paper, [...] Read more.
Approximate computing has been a good paradigm of energy-efficient accelerator design. Accurate and fast error estimation is critical for appropriate approximate techniques selection so that power saving (or performance improvement) can be maximized with acceptable output quality in approximate accelerators. In the paper, we propose HEAP, a Holistic Error assessment framework to characterize multiple Approximate techniques with Probabilistic graphical models (PGM) in a joint way. HEAP maps the problem of evaluating errors induced by different approximate techniques into a PGM issue, including: (1) A heterogeneous Bayesian network is represented by converting an application’s data flow graph, where various approximate options are {precise, approximate} two-state X*-type nodes, while input or operating variables are {precise, approximate, unacceptable} three-state X-type nodes. These two different kinds of nodes are separately used to configure the available approximate techniques and track the corresponding error propagation for guaranteed configurability; (2) node learning is accomplished via an approximate library, which consists of probability mass functions of multiple approximate techniques to fast calculate each node’s Conditional Probability Table by mechanistic modeling or empirical modeling; (3) exact inference provides the probability distribution of output quality at three levels of precise, approximate, and unacceptable. We do a complete case study of 3 × 3 Gaussian kernels with different approximate configurations to verify HEAP. The comprehensive results demonstrate that HEAP is helpful to explore design space for power-efficient approximate accelerators, with just 4.18% accuracy loss and 3.34 × 105 speedup on average over Mentor Carlo simulation. Full article
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Open AccessArticle
Design of Soft-Switching Hybrid DC-DC Converter with 2-Phase Switched Capacitor and 0.8nH Inductor for Standard CMOS Process
Electronics 2020, 9(2), 372; https://doi.org/10.3390/electronics9020372 - 21 Feb 2020
Cited by 1 | Viewed by 1064
Abstract
A soft-switching hybrid DC-DC converter with a 2-phase switched capacitor is proposed for the implementation of a fully-integrated voltage regulator in a 65 nm standard CMOS process. The soft-switching operation is implemented to minimize power loss due to the parasitic capacitance of the [...] Read more.
A soft-switching hybrid DC-DC converter with a 2-phase switched capacitor is proposed for the implementation of a fully-integrated voltage regulator in a 65 nm standard CMOS process. The soft-switching operation is implemented to minimize power loss due to the parasitic capacitance of the flying capacitor. The 2-phase switched capacitor topology keeps the same resonance value for every soft-switching operation, resulting in minimizing the voltage imbalance of the flying capacitor. The proposed adaptive timing generator digitally calibrates the turn-on delay of switches to achieve a complete soft-switching operation. The simulation results show that the proposed soft-switching hybrid DC-DC converter with a 2-phase 2:1 switched capacitor improves the efficiency by 5.1% and achieves 79.5% peak efficiency at a maximum load current of 250 mA. Full article
(This article belongs to the Section Circuit and Signal Processing)
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Open AccessArticle
The High Performance of a Task Scheduling Algorithm Using Reference Queues for Cloud- Computing Data Centers
Electronics 2020, 9(2), 371; https://doi.org/10.3390/electronics9020371 - 21 Feb 2020
Cited by 1 | Viewed by 1551
Abstract
As the network technology continues to grow at a high rate of speed, the traditional network topology is improved with novel distributed topologies such as the Cloud computing network. A cloud computing environment consists of a huge number of processors and memories, high-speed [...] Read more.
As the network technology continues to grow at a high rate of speed, the traditional network topology is improved with novel distributed topologies such as the Cloud computing network. A cloud computing environment consists of a huge number of processors and memories, high-speed networks, and various application services to provide a lot of services over the Internet for users. However, many services need to search for suitable service nodes, and the workload of each node can be unbalanced. Based on the reason above, the Reference Queue based Cloud Service Architecture (RQCSA) and Fitness Service Queue Selection Mechanism (FSQSM) are proposed to handle more tasks, lower the makespan and queue waiting time, and improve efficiency. Moreover, the tasks can be distributed more evenly to avoid overloading cluster managers and lower the efficiency of the system. Full article
(This article belongs to the Special Issue Cloud Computing and Applications)
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Open AccessArticle
Wide Voltage Resonant Converter Using a Variable Winding Turns Ratio
Electronics 2020, 9(2), 370; https://doi.org/10.3390/electronics9020370 - 21 Feb 2020
Cited by 4 | Viewed by 710
Abstract
This paper presents a inductor–inductor–capacitor (LLC) resonant converter with variable winding turns to achieve wide voltage operation (100–400 V) and realize soft switching operation over the entire load range. Resonant converters have been developed for consumer power units in computers, power servers, medical [...] Read more.
This paper presents a inductor–inductor–capacitor (LLC) resonant converter with variable winding turns to achieve wide voltage operation (100–400 V) and realize soft switching operation over the entire load range. Resonant converters have been developed for consumer power units in computers, power servers, medical equipment, and adaptors due to the advantages of less switching loss and better circuit efficiency. The main disadvantages of the LLC resonant converter are narrow voltage range operation owing to wide switching frequency variation and limited voltage gain. For computer power supplies with hold-up time function, electric vehicle battery chargers, and for power conversion in solar panels, wide input voltage or wide output voltage operation capability is normally demanded for powered electronics. To meet these requirements, the variable winding turns are used in the presented circuit to achieve high- or low-voltage gain when Vin is at low- or high-voltage, respectively. Therefore, the wide voltage operation capability can be implemented in the presented resonant circuit. The variable winding turns are controlled by an alternating current (AC) power switch with two back-to-back metal-oxide-semiconductor field-effect transistors (MOSFETs). A 500-W prototype is implemented and test results are presented to confirm the converter performance. Full article
(This article belongs to the Section Power Electronics)
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Open AccessFeature PaperReview
Nonlinear Dynamics, Switching Kinetics and Physical Realization of the Family of Chua Corsage Memristors
Electronics 2020, 9(2), 369; https://doi.org/10.3390/electronics9020369 - 21 Feb 2020
Viewed by 868
Abstract
This article reviews the nonlinear dynamical attributes, switching kinetics, bifurcation analysis, and physical realization of a family of generic memristors, namely, Chua corsage memristors (CCM). CCM family contains three 1-st order generic memristor dubbed as 2-lobe, 4-lobe, and 6-lobe Chua corsage [...] Read more.
This article reviews the nonlinear dynamical attributes, switching kinetics, bifurcation analysis, and physical realization of a family of generic memristors, namely, Chua corsage memristors (CCM). CCM family contains three 1-st order generic memristor dubbed as 2-lobe, 4-lobe, and 6-lobe Chua corsage memristors and can be distinguished in accordance with their asymptotic stable states. The 2-lobe CCM has two asymptotically stable equilibrium states and regarded as a binary memory device. In contrast, the versatile 4-lobe CCM and 6-lobe CCM are regarded as a multi-bit-per-cell memory device as they exhibit three and four asymptotic stable states, respectively, on their complex and diversified dynamic routes. Due to the diversified dynamic routes, the CC memristors exhibit a highly nonlinear DC V-I curve. Unlike most published highly-nonlinear DC V-I curves with several disconnected branches, the DC V-I curves of CCMs are contiguous along with a locally active negative slope region. Moreover, the DC V-I curves and parametric representations of the CCMs are explicitly analytical. Switching kinetics of the CCM family can be demonstrated with universal formulas of exponential state trajectories xn(t), time period tfn, and applied minimum pulse amplitude VA and width Δw. These formulas are regarded universal as they can be applied to any piecewise linear dynamic routes for any DC or pulse input and with any number of segments. When local activity, and bifurcation and chaos theorems are employed, CMMs exhibit unique stable limit cycles spawn from a supercritical Hopf bifurcation along with static attractors. In addition, the nonlinear circuit and system theoretic approach is applied to explain the asymptotic stability behavior of CCMs and to design real memristor emulators using off-the-shelf circuit components. Full article
(This article belongs to the Section Artificial Intelligence)
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Open AccessArticle
Hardware-Simulator Development and Implementation for Hydraulic Turbine Generation Systems in a District Heating System
Electronics 2020, 9(2), 368; https://doi.org/10.3390/electronics9020368 - 21 Feb 2020
Cited by 2 | Viewed by 820
Abstract
This paper presents not only a hardware-simulator development for hydraulic turbine generation systems (HTGS) in a district heating system (DHS) but also its control strategies and sequence. Generally, a DHS uses a differential pressure control valve (DPCV) to supply high-pressure–high-temperature fluids for customers [...] Read more.
This paper presents not only a hardware-simulator development for hydraulic turbine generation systems (HTGS) in a district heating system (DHS) but also its control strategies and sequence. Generally, a DHS uses a differential pressure control valve (DPCV) to supply high-pressure–high-temperature fluids for customers depending on distance. However, long-term exposure of the DPCV to fluids increases the probability of cavitation and leads to heat loss in an event of cavitation. Therefore, a HTGS was introduced to solve this problem. It performs differential pressure control of the fluids, replaces the DPCV, and converts excess energy wasted by the DPCV to electrical energy. In this paper, the development of a hardware-simulator for HTGSs with a back-to-back converter, which uses two-level topologies, is proposed; moreover, control strategies and sequence used in this design are presented. The performance and validity of the proposed hardware-simulator and its control strategies are demonstrated by experimental results. Full article
(This article belongs to the Special Issue High Power Electric Traction Systems)
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Open AccessFeature PaperReview
Socially Assistive Robots for Older Adults and People with Autism: An Overview
Electronics 2020, 9(2), 367; https://doi.org/10.3390/electronics9020367 - 21 Feb 2020
Cited by 8 | Viewed by 1699
Abstract
Over one billion people in the world suffer from some form of disability. Nevertheless, according to the World Health Organization, people with disabilities are particularly vulnerable to deficiencies in services, such as health care, rehabilitation, support, and assistance. In this sense, recent technological [...] Read more.
Over one billion people in the world suffer from some form of disability. Nevertheless, according to the World Health Organization, people with disabilities are particularly vulnerable to deficiencies in services, such as health care, rehabilitation, support, and assistance. In this sense, recent technological developments can mitigate these deficiencies, offering less-expensive assistive systems to meet users’ needs. This paper reviews and summarizes the research efforts toward the development of these kinds of systems, focusing on two social groups: older adults and children with autism. Full article
(This article belongs to the Special Issue Machine Learning Techniques for Assistive Robotics)
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Open AccessArticle
Power Quality Assessment of Grid-Connected PV System in Compliance with the Recent Integration Requirements
Electronics 2020, 9(2), 366; https://doi.org/10.3390/electronics9020366 - 21 Feb 2020
Cited by 13 | Viewed by 1292
Abstract
The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have increased dramatically over the past two decades. In this sense, and to ensure a high quality of the PVPPs generated power as well as a contribution on the power [...] Read more.
The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have increased dramatically over the past two decades. In this sense, and to ensure a high quality of the PVPPs generated power as well as a contribution on the power system security and stability, some of the new power quality requirements imposed by different grid codes and standards in order to regulate the installation of PVPPs and ensure the grid stability. This study aims to investigate the recent integration requirements including voltage sag, voltage flicker, harmonics, voltage unbalance, and frequency variation. Additionally, compliance controls and methods to fulfill these requirements are developed. In line with this, a large-scale three-phase grid-connected PVPP is designed. A modified inverter controller without the use of any extra device is designed to mitigate the sage incidence and achieve the low-voltage ride-through requirement. It can efficiently operate at normal conditions and once sag or faults are detected, it can change the mode of operation and inject a reactive current based on the sag depth. A dynamic voltage regulator and its controller are also designed to control the voltage flicker, fluctuation, and unbalance at the point of common coupling between the PVPP and the grid. The voltage and current harmonics are reduced below the specified limits using proper design and a RLC filter. The obtained results show that the proposed controller fulfilled the recent standard requirements in mitigating power quality (PQ) events. Thus, this study can increase the effort towards the development of smooth PVPP integration by optimizing the design, operation and control strategies towards high PQ and green electricity. Full article
(This article belongs to the Special Issue Fault Detection and Diagnosis of Intelligent Mechatronic Systems)
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Open AccessArticle
Realization of the Sensorless Permanent Magnet Synchronous Motor Drive Control System with an Intelligent Controller
Electronics 2020, 9(2), 365; https://doi.org/10.3390/electronics9020365 - 21 Feb 2020
Cited by 5 | Viewed by 1303
Abstract
This paper presents the sensorless control algorithm for a permanent magnet synchronous motor (PMSM) drive system with the estimator and the intelligent controller. The estimator is constructed on the novel sliding mode observer (SMO) in combination with a phase-locked loop (PLL) to estimate [...] Read more.
This paper presents the sensorless control algorithm for a permanent magnet synchronous motor (PMSM) drive system with the estimator and the intelligent controller. The estimator is constructed on the novel sliding mode observer (SMO) in combination with a phase-locked loop (PLL) to estimate the position and speed of the rotor. The intelligent controller is a radial basis function neural network (RBFNN)-based self-tuning PID (Proportional-Integral-Derivative) controller, applied to the velocity control loop of the PMSM drive control system to adapt strongly to dynamic characteristics during the operation with an external load. The I-f startup strategy is adopted to accelerate the motor from standstill, then switches to the sensorless mode smoothly. The control algorithm program is based on MATLAB and can be executed in simulations and experiments. The control system performance is verified on an experimental platform with various speeds and the dynamic load, in which the specified I-f startup mode and sensorless mode, inspected by tracking response and speed regulation. The simulation and experimental results demonstrate that the proposed method has worked successfully. The motor control system has smooth switching, good tracking response, and robustness against disturbance. Full article
(This article belongs to the Special Issue Advanced Control Systems for Electric Drives)
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Open AccessArticle
Automatic Control and Model Verification for a Small Aileron-Less Hand-Launched Solar-Powered Unmanned Aerial Vehicle
Electronics 2020, 9(2), 364; https://doi.org/10.3390/electronics9020364 - 21 Feb 2020
Cited by 3 | Viewed by 835
Abstract
This paper describes a low-cost flight control system of a small aileron-less hand-launched solar-powered unmanned aerial vehicle (UAV). In order to improve the accuracy of the whole system model and quantify the influence of each subsystem, detailed modeling of UAV energy and a [...] Read more.
This paper describes a low-cost flight control system of a small aileron-less hand-launched solar-powered unmanned aerial vehicle (UAV). In order to improve the accuracy of the whole system model and quantify the influence of each subsystem, detailed modeling of UAV energy and a control system including a solar model, engine, energy storage, sensors, state estimation, control law, and actuator module are established in accordance with the experiment and component principles. A whole system numerical simulation combined with the 6 degree-of-freedom (DOF) simulation model is constructed based on the typical mission route, and the parameter precision sequence and energy balance are obtained. Then, a hardware-in-the-loop (HIL) experiment scheme based on the Stewart platform (SP) is proposed, and three modes of acceleration, angular velocity, and attitude are designed to verify the control system through the inner and boundary states of the flight envelope. The whole system scheme is verified by flight tests at different altitudes, and the aerodynamic force coefficient and sensor error are corrected by flight data. With the increase of altitude, the cruise power increases from 47 W to 78 W, the trajectory tracking precision increases from 23 m to 44 m, the sensor measurement noise increases, and the bias decreases. Full article
(This article belongs to the Special Issue Autonomous Vehicles Technology)
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Open AccessFeature PaperArticle
Demand and Storage Management in a Prosumer Nanogrid Based on Energy Forecasting
Electronics 2020, 9(2), 363; https://doi.org/10.3390/electronics9020363 - 21 Feb 2020
Cited by 1 | Viewed by 846
Abstract
Energy efficiency and consumers’ role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a [...] Read more.
Energy efficiency and consumers’ role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a prosumer nanogrid. Firstly, energy monitoring is performed and time-space compression is applied as a tool for forecasting energy resources and power quality (PQ) indices; secondly, demand is managed, taking advantage of smart appliances (SA) to reduce the electricity bill; finally, energy storage systems (ESS) are also managed to better match the forecasted generation of each prosumer. Results show how these strategies can be coordinated to contribute to energy management in the prosumer nanogrid. A simulation test is included, which proves how effectively the prosumers’ power converters track the power setpoints obtained from the proposed strategy. Full article
(This article belongs to the Special Issue Energy Management Based on Internet of Things)
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Open AccessArticle
CMOS Analog Filter Design for Very High Frequency Applications
Electronics 2020, 9(2), 362; https://doi.org/10.3390/electronics9020362 - 21 Feb 2020
Cited by 7 | Viewed by 884
Abstract
A design strategy for the synthesis of high-selectivity/low-order analog filters in Complementary Metal-Oxide-Semiconductor (CMOS) technology for very high frequency (VHF) applications is presented. The methodology for the reconstitution of a given transfer function by means of Signal Flow Graphs (SFG) manipulation in canonical [...] Read more.
A design strategy for the synthesis of high-selectivity/low-order analog filters in Complementary Metal-Oxide-Semiconductor (CMOS) technology for very high frequency (VHF) applications is presented. The methodology for the reconstitution of a given transfer function by means of Signal Flow Graphs (SFG) manipulation in canonical form is proposed leading to a fully differential g m -C biquad filter. As a practical example, the design of a notch filter intended to suppress interferers in the lower sideband (400 MHz) of the Medical Implant Communication Service (MICS), in single-poly, 6-metal layers; Mixed-Signal/RF 0.18 µm CMOS technology is realized. To compare the performance of the proposal with some other solution, the design of a 7th order elliptic notch filter based on Frequency Dependent Negative Resistors (FDNRs) was also accomplished. The attained simulation results prove that the proposal is competitive compared to the FDNR solution and some other state-of-the-art filters reported in the literature. The most salient features of the proposed notch biquad include: the selectivity, whose value is comparable to that of a 7th order elliptic approach and some other 3rd order filters; a high-frequency operation without resonators; linearity, with a +15 dBm I I P 3 ; a reduced form factor with a total occupied area of 0.004282 mm2 and mostly a low design complexity. Full article
(This article belongs to the Section Circuit and Signal Processing)
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Open AccessArticle
BiometricAccessFilter: A Web Control Access System Based on Human Auditory Perception for Children Protection
Electronics 2020, 9(2), 361; https://doi.org/10.3390/electronics9020361 - 21 Feb 2020
Cited by 2 | Viewed by 1278
Abstract
Along with internet growth, security issues come into existence. Efficient tools to control access and to filter undesirable web content are needed all the time. In this paper, a control access method for web security based on age estimation is proposed, where the [...] Read more.
Along with internet growth, security issues come into existence. Efficient tools to control access and to filter undesirable web content are needed all the time. In this paper, a control access method for web security based on age estimation is proposed, where the correlation between human age and auditory perception is taken into account. In particular, access is denied if a person’s age is not appropriate for the given web content. Unlike existing web access filters, our biometric approach offers greater security and protection to individual privacy. From a technical point of view, the machine-learning regression model is used to estimate the person’s age. The primary contributions of this paper include an age estimation module based on human auditory perception and provision of an open-source web filter to prevent adults from accessing children web applications. The proposed system can also be used to limit the access of children to a webpage specially designed for adults. Our system is evaluated with a dataset collected from 201 persons with different ages from 06 to 60 years old, where it considered 109 male and 82 female volunteers. Results indicate that our system can estimate the age of a person with an accuracy of 97.04% and a root mean square error (RMSE) of 4.2 years. It presents significant performances in the verification scenario with an Equal Error Rate (EER) of 1.4%. Full article
(This article belongs to the Special Issue Sensing and Signal Processing in Smart Healthcare)
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Open AccessArticle
Optimization of Public Transport Services to Minimize Passengers’ Waiting Times and Maximize Vehicles’ Occupancy Ratios
Electronics 2020, 9(2), 360; https://doi.org/10.3390/electronics9020360 - 20 Feb 2020
Cited by 1 | Viewed by 884
Abstract
Determining the best timetable for vehicles in a public transportation (PT) network is a complex problem, especially because it is just necessary to consider the requirements and satisfaction of passengers as the requirements of transportation companies. In this paper, a model of the [...] Read more.
Determining the best timetable for vehicles in a public transportation (PT) network is a complex problem, especially because it is just necessary to consider the requirements and satisfaction of passengers as the requirements of transportation companies. In this paper, a model of the PT timetabling problem which takes into consideration the passenger waiting time (PWT) at a station and the vehicle occupancy ratio (VOR) is proposed. The solution aims to minimize PWT and maximize VOR. Due to the large search space of the problem, we use a multiobjective particle swarm optimization (MOPSO) algorithm to arrive at the solution of the problem. The results of the proposed method are compared with similar results from the existing literature. Full article
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Open AccessArticle
Three Closed-Loop Feedback Control System with Dual Disturbance Observers of an Optoelectronic Stable Control Platform
Electronics 2020, 9(2), 359; https://doi.org/10.3390/electronics9020359 - 20 Feb 2020
Cited by 2 | Viewed by 710
Abstract
Disturbances presented in aeronautical imaging equipment can cause visual axis jitter, which directly leads to a reduction in closed-loop bandwidth and a decrease in tracking accuracy. The disturbance frequency affecting the stable control platform is mainly concentrated in the low- and middle-frequency bands, [...] Read more.
Disturbances presented in aeronautical imaging equipment can cause visual axis jitter, which directly leads to a reduction in closed-loop bandwidth and a decrease in tracking accuracy. The disturbance frequency affecting the stable control platform is mainly concentrated in the low- and middle-frequency bands, but the commonly used three closed-loop feedback control methods do not perform well in the disturbance rejection of those frequency bands. Moreover, the only disturbance observer in the acceleration loop cannot improve the low-band disturbance rejection capability due to the drift of the micro-electro-mechanical-system (MEMS) accelerometers in the low-frequency range. To solve these problems, this paper proposed dual disturbance observers (dual DOB) based on the disturbance information in the acceleration loop and the position loop. This design used two compensators to observe and compensate for the disturbances, which did not require additional sensors, and therefore did not increase system cost. Theoretical demonstrations and physical experiments showed that the designed method of the dual DOB not only improved the disturbance rejection capability of the low- and middle-frequency band of the optoelectronic stable control platform, but also improved the robustness of the system. Full article
(This article belongs to the Section Systems & Control Engineering)
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Open AccessArticle
Research on Simplified Model of AC/DC Hybrid Microgrid for Fault Analysis
Electronics 2020, 9(2), 358; https://doi.org/10.3390/electronics9020358 - 20 Feb 2020
Cited by 2 | Viewed by 716
Abstract
The AC/DC hybrid microgrid, which takes into account the access requirements of AC and DC sources and loads, optimizes the structure of traditional distribution networks. The application of power electronic transformers as the core of its energy management, with electrical isolation and accurate [...] Read more.
The AC/DC hybrid microgrid, which takes into account the access requirements of AC and DC sources and loads, optimizes the structure of traditional distribution networks. The application of power electronic transformers as the core of its energy management, with electrical isolation and accurate control of the voltage, current and power flow by the control system, enables the microgrid to achieve a more flexible and stable transmission mode. Because the power electronic transformer combines the power electronic device and the high-frequency transformer, its frequent switching causes the electromagnetic transient simulation to take too long. Therefore, by simplifying control loops and converters, this paper proposes a simplified model for the microgrid system power flow and the dynamic response under exposure to a fault. The mathematical model equivalent simplification method is used in this paper. This method is concise and efficient and does not rely on the performance of a computer or change the program algorithm of the software. The simplified model was built based on PSCAD (Power System Computer Aided Design) simulation software and was carried out under short circuit fault conditions to verify its validity. The comparison of the simulation’s time consumption and accuracy shows that model simplification can significantly improve the simulation speed, with an acceptable error rate, and its dynamic response maintains good consistency with that of the detailed electromagnetic transient model. Therefore, it can be applied to the transient electromagnetic simulation fault analysis of the AC/DC hybrid microgrid. Full article
(This article belongs to the Special Issue New Technologies for Smart Distribution Grid)
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Open AccessArticle
Assessment of Structural Performance and Integrity for Vibration-based Energy Harvester in Frequency Domain
Electronics 2020, 9(2), 357; https://doi.org/10.3390/electronics9020357 - 20 Feb 2020
Cited by 1 | Viewed by 656
Abstract
A vibration-based energy harvester (VEH) utilizes vibrations originated from various structures and specifically maximizes the displacement of its moving parts, using the resonance between the frequency of external vibration loads from the structure and the natural frequency of VEH to improve power production [...] Read more.
A vibration-based energy harvester (VEH) utilizes vibrations originated from various structures and specifically maximizes the displacement of its moving parts, using the resonance between the frequency of external vibration loads from the structure and the natural frequency of VEH to improve power production efficiency. This study presents the procedure to evaluate the structural performance and structural integrity of VEH utilized in a railway vehicle under frequency domain. First of all, a structural performance test was performed to identify the natural frequency and assess the structural response in frequency domain. Then, the static structural analysis was carried out using FE analysis to investigate the failure critical locations (FCLs) and effect of resonance. Finally, we conducted a frequency response analysis to identify the structural response and investigate the structural integrity in frequency domain. Based on these results, the authors assessed the structural performance and integrity of VEHs in two versions. Full article
(This article belongs to the Special Issue Energy Harvesting and Storage Applications)
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Open AccessArticle
An Energy Storage System’s Operational Management and Control Method Considering a Battery System
Electronics 2020, 9(2), 356; https://doi.org/10.3390/electronics9020356 - 20 Feb 2020
Cited by 1 | Viewed by 765
Abstract
Losses in energy storage systems (ESSs) result from losses in battery systems and power conversion systems (PCSs). Thus, the power difference between the input and output occurs as a loss, which is considered an operational cost. Additionally, since battery systems consist of modules, [...] Read more.
Losses in energy storage systems (ESSs) result from losses in battery systems and power conversion systems (PCSs). Thus, the power difference between the input and output occurs as a loss, which is considered an operational cost. Additionally, since battery systems consist of modules, there is always a temperature difference. Even if voltage balancing is conducted, deviations between the state of health (SoH) and state of charge (SoC) always exist. Therefore, a battery characteristic should be considered in relation to the efficient operation of an ESS. In this paper, charging control is implemented based on the SoC. When errors occur in the beginning, the coulomb counting method (CCM) continues to produce errors; it also calculates the SoC through an improved equation. Thus, it can calculate the SoC by using high-accuracy initial values. Moreover, battery deterioration occurs during charging and discharging, which increases a battery’s internal resistance. This reduces the switching time to the battery cut-off voltage or constant voltage (CV) mode, so it becomes possible to calculate the SoH. Therefore, in this paper, the algorithms and equations are proposed to perform SoH operations according to the charging time that is able to reach CV after charging. A conventional battery is usually charged by using constant current (CC) charging until the voltage of the battery module reaches the cut-off area. A switch to CV then occurs when the cut-off area is reached and maintained. However, SoC-based selective charging control is carried out to prevent heat problems. In addition, the battery is charged safely and efficiently by conducting SoH prediction considering the battery thermal characteristics, which vary depending on the charging time and other characteristics. In this paper, a 3 kW ESS was produced, and the proposed algorithm’s feasibility was verified. Full article
(This article belongs to the Section Power Electronics)
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Open AccessFeature PaperArticle
Recognition of Gait Phases with a Single Knee Electrogoniometer: A Deep Learning Approach
Electronics 2020, 9(2), 355; https://doi.org/10.3390/electronics9020355 - 20 Feb 2020
Cited by 4 | Viewed by 1005
Abstract
Artificial neural networks were satisfactorily implemented for assessing gait events from different walking data. This study aims to propose a novel approach for recognizing gait phases and events, based on deep-learning analysis of only sagittal knee-joint angle measured by a single electrogoniometer per [...] Read more.
Artificial neural networks were satisfactorily implemented for assessing gait events from different walking data. This study aims to propose a novel approach for recognizing gait phases and events, based on deep-learning analysis of only sagittal knee-joint angle measured by a single electrogoniometer per leg. Promising classification/prediction performances have been previously achieved by surface-EMG studies; thus, a further aim is to test if adding electrogoniometer data could improve classification performances of state-of-the-art methods. Gait data are measured in about 10,000 strides from 23 healthy adults, during ground walking. A multi-layer perceptron model is implemented, composed of three hidden layers and a one-dimensional output. Classification/prediction accuracy is tested vs. ground truth represented by foot–floor-contact signals, through samples acquired from subjects not seen during training phase. Average classification-accuracy of 90.6 ± 2.9% and mean absolute value (MAE) of 29.4 ± 13.7 and 99.5 ± 28.9 ms in assessing heel-strike and toe-off timing are achieved in unseen subjects. Improvement of classification-accuracy (four points) and reduction of MAE (at least 35%) are achieved when knee-angle data are used to enhance sEMG-data prediction. Comparison of the two approaches shows as the reduction of set-up complexity implies a worsening of mainly toe-off prediction. Thus, the present electrogoniometer approach is particularly suitable for the classification tasks where only heel-strike event is involved, such as stride recognition, stride-time computation, and identification of toe walking. Full article
(This article belongs to the Special Issue Recent Advances in Motion Analysis)
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Open AccessArticle
An Express Algorithm for Transient Electromagnetic Data Interpretation
Electronics 2020, 9(2), 354; https://doi.org/10.3390/electronics9020354 - 20 Feb 2020
Cited by 2 | Viewed by 800
Abstract
The transient electromagnetic (TEM) method is a time-domain, controlled source, electromagnetic (EM) geophysical technique which is often applied to image the subsurface conductivity distributions of shallow layers due to its effectiveness and adaptability to complex site working conditions. The means for an express [...] Read more.
The transient electromagnetic (TEM) method is a time-domain, controlled source, electromagnetic (EM) geophysical technique which is often applied to image the subsurface conductivity distributions of shallow layers due to its effectiveness and adaptability to complex site working conditions. The means for an express analysis of such experimental data in several practical cases have advantages and are suitable for use. We developed our approach for determining the approximate one-dimensional (1D) model of background conductivity based on the formal transformation of the TEM experimental data and the mathematical analysis of continuous functions. Our algorithm, which allows the 1D model’s parameters to be obtained in terms of a layer’s thickness and resistivity, widely utilizes the numerical differentiation of experimental curves as well as of transformed ones. Since the noise level increases with time in the attenuating TEM signals and differentiation even enhances it, special procedures are required to calculate the derivative values. We applied the piecewise cubic spline approximation to solve this problem. In that case, the derivatives are obtained using polynomial coefficients which are available for each node. The application of the created facilities is demonstrated using real experimental data of the TEM soundings. Full article
(This article belongs to the Special Issue Electronization of Businesses - Systems Engineering and Analytics)
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Open AccessArticle
BPR-TCAM—Block and Partial Reconfiguration based TCAM on Xilinx FPGAs
Electronics 2020, 9(2), 353; https://doi.org/10.3390/electronics9020353 - 19 Feb 2020
Cited by 2 | Viewed by 1061
Abstract
Field Programmable Gate Arrays (FPGAs) based Ternary Content Addressable Memories (TCAMs) are widely used in high-speed networking applications.However, TCAMs are not present on state-of-the-art FPGAs and need to be emulated on SRAM-based memories (i.e., LUTRAMs and Block RAMs) which requires a large amount [...] Read more.
Field Programmable Gate Arrays (FPGAs) based Ternary Content Addressable Memories (TCAMs) are widely used in high-speed networking applications.However, TCAMs are not present on state-of-the-art FPGAs and need to be emulated on SRAM-based memories (i.e., LUTRAMs and Block RAMs) which requires a large amount of FPGA resources. In this paper, we present an efficient methodology to implement FPGA-based TCAMs with significant resource savings compared to existing schemes. The proposed methodology exploits the fracturable nature of Look Up Tables (LUTs) and the built-in slice carry-chains for simultaneous mapping of two rules and its matching logic to a single FPGA slice. Multiple slices can be stacked together to build deeper and wider TCAMs in a modular way. The combination of all these techniques results in significant savings in resource utilization compared to existing approaches. Full article
(This article belongs to the Section Networks)
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Open AccessArticle
Cooperative Secure Transmission in MISO-NOMA Networks
Electronics 2020, 9(2), 352; https://doi.org/10.3390/electronics9020352 - 19 Feb 2020
Cited by 1 | Viewed by 735
Abstract
In this paper, we investigate cooperative secure transmission in non-orthogonal multiple access (NOMA) networks where a source (Alice) intends to transmit confidential messages to one legitimate user with high-level security requirement (LU1), and serve another normal one (LU2) simultaneously. In order to enhance [...] Read more.
In this paper, we investigate cooperative secure transmission in non-orthogonal multiple access (NOMA) networks where a source (Alice) intends to transmit confidential messages to one legitimate user with high-level security requirement (LU1), and serve another normal one (LU2) simultaneously. In order to enhance the transmission security, a cooperative jammer (Charlie) is employed to confuse multiple non-colluding eavesdroppers (Eves). Taking both secrecy outage restriction of LU1 and the desired quality of service (QoS) requirement of LU2 into consideration, we propose an adaptive power allocation strategy for maximizing secrecy rate. Numerical results are provided to validate that our proposed scheme significantly outperforms the conventional NOMA secure transmission scheme. Full article
(This article belongs to the Special Issue Cooperative Communications for Future Wireless Systems)
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Open AccessFeature PaperArticle
A Baseline Roadmap for Advanced Wireless Research Beyond 5G
Electronics 2020, 9(2), 351; https://doi.org/10.3390/electronics9020351 - 19 Feb 2020
Cited by 3 | Viewed by 2434
Abstract
This paper presents a baseline roadmap for the evolution of 5G new radio over the next decade. Three timescales are considered, namely short-term (2022-ish), medium-term (2025-ish), and long-term (2030-ish). The evolution of the target key performance indicators (KPIs) is first analyzed by accounting [...] Read more.
This paper presents a baseline roadmap for the evolution of 5G new radio over the next decade. Three timescales are considered, namely short-term (2022-ish), medium-term (2025-ish), and long-term (2030-ish). The evolution of the target key performance indicators (KPIs) is first analyzed by accounting for forecasts on the emerging use cases and their requirements, together with assumptions on the pace of technology advancements. The baseline roadmap is derived next by capturing the top-10 and next the top-5 technology trends envisioned to bring significant added value at each timescale. Being intrinsically predictive, our proposed baseline roadmap cannot assert with certainty the values of the target KPIs and the shortlisting of the technology trends. It is, however, aimed at driving discussions and collecting feedback from the wireless research community for future tuning and refinement as the 5G evolution journey progresses. Full article
(This article belongs to the Special Issue Beyond 5G Evolution)
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Open AccessArticle
sDeepFM: Multi-Scale Stacking Feature Interactions for Click-Through Rate Prediction
Electronics 2020, 9(2), 350; https://doi.org/10.3390/electronics9020350 - 19 Feb 2020
Cited by 1 | Viewed by 769
Abstract
For estimating the click-through rate of advertisements, there are some problems in that the features cannot be automatically constructed, or the features built are relatively simple, or the high-order combination features are difficult to learn under sparse data. To solve these problems, we [...] Read more.
For estimating the click-through rate of advertisements, there are some problems in that the features cannot be automatically constructed, or the features built are relatively simple, or the high-order combination features are difficult to learn under sparse data. To solve these problems, we propose a novel structure multi-scale stacking pooling (MSSP) to construct multi-scale features based on different receptive fields. The structure stacks multi-scale features bi-directionally from the angles of depth and width by constructing multiple observers with different angles and different fields of view, ensuring the diversity of extracted features. Furthermore, by learning the parameters through factorization, the structure can ensure high-order features being effectively learned in sparse data. We further combine the MSSP with the classical deep neural network (DNN) to form a unified model named sDeepFM. Experimental results on two real-world datasets show that the sDeepFM outperforms state-of-the-art models with respect to area under the curve (AUC) and log loss. Full article
(This article belongs to the Special Issue Regularization Techniques for Machine Learning and Their Applications)
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