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Atherosclerotic cardiovascular disease is a major cause of human disability and mortality. Our previous study demonstrated the safety and efficacy of sonodynamic therapy (SDT) on atherosclerotic plaques. However, traditional single-element therapeutic transducer has single acoustic field, and positioning therapeutic and imaging transducers in the same position is difficult during ultrasound imaging-guided SDT. Continuously changing the position of transducers to intervene lesions in different positions is required, increasing the difficulty of treatment. Thus, an SDT device with precise theranostics is required. Therefore, we designed and fabricated a “concentric ultrasound transducer for theranostics” (CUST-T), comprising a central 8-MHz linear array transducer for ultrasound imaging, and a peripheral 1-MHz hollow two-dimensional (2-D) planar array transducer for generating phased-array focused ultrasound (PAFUS). The CUST-T exhibited high imaging resolution at a distance of up to 20 mm from the transducer and could generate a personalized complex PAFUS acoustic field to match various lesions. In vitro biomedical results showed that PAFUS-SDT induced RAW264.7-derived foam cell apoptosis leading to a targeting field apoptotic rate 4.36–6.24 times that of the nontargeting field and the significant apoptotic region was consistent with the PAFUS acoustic field. In vivo, PAFUS-SDT guided by ultrasound imaging significantly increased the lumen area (${P} < 0.05$) and collagen level (${P} < 0.01$), whereas the wall thickness (${P} < 0.05$) and lipid content (${P} < 0.01$) of rabbit femoral artery were reduced. In conclusion, CUST-T provided image guidance sufficient for accurate SDT for atherosclerotic plaques in peripheral arteries and could be applied in clinical practice. [ABSTRACT FROM AUTHOR]

As a complex nonlinear system, the power system in operation may experience chaotic oscillation which can threaten the stability of the system for unexpected events and uncertain factors. Initially, through considering factors such as the generators, the power system node voltage amplitude and phase angle, this brief establishes a fourth-order power system dynamic model and a two-parameter fourth-order power system mathematical model with load reactive power and mechanical input power as chaotic parameters to explore the mechanism and characteristics of chaos in the power system with the chaos theory. In addition, a sliding mode controller based on exponential reaching law for four state variables is designed, which is used to suppress the chaotic oscillation of the power system and guarantee the system can work stably at the target operating point within the chaotic parameter range. The designed controller can effectively suppress the chaos in power system and has an ideal performance. [ABSTRACT FROM AUTHOR]

A symmetry relation of the integral operators in a layered medium proved by the reciprocal theory can be applied to improve the accuracy of the magnetic-field integral equation (MFIE). Based on the symmetric layered medium Green’s function, the normal vector can be transferred into the inner integral to keep the field integral as the inner integral of the elements in the impedance matrix. When discretized by the divergence-conforming function, this field-extracted scheme shows better performance than the classic expression in accuracy. Meanwhile, this form of expression can be applied in the combined-field integral equation (CFIE). Several numerical results are provided to validate the formulation of the symmetry relations from the layered medium Green’s function to the impedance matrices and to reveal its advantages in enhancing the accuracy of the field-extracted form of MFIE. [ABSTRACT FROM AUTHOR]

Attention mechanisms have significantly boosted the performance of video classification neural networks thanks to the utilization of perspective contexts. However, the current research on video attention generally focuses on adopting a specific aspect of contexts (e.g., channel, spatial/temporal, or global context) to refine the features and neglects their underlying correlation when computing attentions. This leads to incomplete context utilization and hence bears the weakness of limited performance improvement. To tackle the problem, this paper proposes an efficient attention-in-attention (AIA) method for element-wise feature refinement, which investigates the feasibility of inserting the channel context into the spatio-temporal attention learning module, referred to as CinST, and also its reverse variant, referred to as STinC. Specifically, we instantiate the video feature contexts as dynamics aggregated along a specific axis with global average and max pooling operations. The workflow of an AIA module is that the first attention block uses one kind of context information to guide the gating weights calculation of the second attention that targets at the other context. Moreover, all the computational operations in attention units act on the pooled dimension, which results in quite few computational cost increase (< 0.02%). To verify our method, we densely integrate it into two classical video network backbones and conduct extensive experiments on several standard video classification benchmarks. The source code of our AIA is available at https://github.com/haoyanbin918/Attention-in-Attention. [ABSTRACT FROM AUTHOR]

Deterministic executions of computation-intensive and delay-sensitive tasks are vital for realizing Industry 4.0. Multi-access edge computing (MEC) enables critical tasks to be offloaded to the network edge for quickly responding and processing tasks locally. However, during workload peaks at the resource-limited edge, the best effort IP forwarding in the typical network architecture incurs long-tail latency at both the access and interconnection networks of MEC systems. The long-tail latency results in strict service level agreements (SLAs) unable to be guaranteed in end-to-end communication. In this article, we propose a task deterministic network (TDN) architecture that provides communication with bounded low latency and zero jitter for critical tasks among MEC systems. In TDN, the cross-domain collaboration mechanisms of the layer 2/layer 3 deterministic networking and 5G are jointly designed to eliminate the long-tail latency in typical MEC system networks. In addition, we design a seamless working scheme for the time-sensitive networking controller, the MEC orchestrator, and other coordinators to enable edge collaboration and global deterministic forwarding. Moreover, the main functions of TDN are detailed, including clock synchronization, network slicing, cycle mapping, and multi-layer collaboration. Finally, we present simulation results to substantiate the performance of TDN for accommodating critical service flows among MEC systems. [ABSTRACT FROM AUTHOR]

Efficient action recognition aims to classify a video clip into a specific action category with a low computational cost. It is challenging since the integrated spatial-temporal calculation (e. g., 3D convolution) introduces intensive operations and increases complexity. This paper explores the feasibility of the integration of channel splitting and filter decoupling for efficient architecture design and feature refinement by proposing a novel spatio-temporal collaborative (STC) module. STC splits the video feature channels into two groups and separately learns spatio-temporal representations in parallel with decoupled convolutional operators. Particularly, STC consists of two computation-efficient blocks, i.e., $\text {S}_{\mathrm{ T}}$ and $\text {T}_{\mathrm{ S}}$ , where they extract either spatial (${S}_{\cdot }$) or temporal (${T}_{\cdot }$) features and further refine their features with either temporal ($\cdot _{T}$) or spatial ($\cdot _{S}$) contexts globally. The spatial/temporal context refers to information dynamics aggregated from temporal/spatial axis. To thoroughly examine our method’s performance in video action recognition tasks, we conduct extensive experiments using five video benchmark datasets requiring temporal reasoning. Experimental results show that the proposed STC networks achieve a competitive trade-off between model efficiency and effectiveness. [ABSTRACT FROM AUTHOR]

Face recognition has witnessed significant progress with the advances of deep convolutional neural networks (CNNs), and the central task of which is how to improve the feature discrimination. To this end, several margin-based (e.g., angular, additive and additive angular margins) softmax loss functions have been proposed to increase the feature margin between different classes. However, despite great achievements have been made, they mainly suffer from four issues: 1) They are based on the assumption of well-cleaned training sets, without considering the consequence of noisy labels inherently existing in most of face recognition datasets; 2) They ignore the importance of informative (e.g., semi-hard) features mining for discriminative learning; 3) They encourage the feature margin only from the perspective of ground truth class, without realizing the discriminability from other non-ground truth classes; and 4) They set the feature margin between different classes to be same and fixed, which may not adapt the situation of unbalanced data in different classes very well. To cope with these issues, this paper develops a novel loss function, which explicitly estimates the noisy labels to drop them and adaptively emphasizes the semi-hard feature vectors from the remaining reliable ones to guide the discriminative feature learning. Thus we can address all the above issues and achieve more discriminative features for face recognition. To the best of our knowledge, this is the first attempt to inherit the advantages of feature-based noisy labels detection, feature mining and feature margin into a unified loss function. Extensive experimental results on a variety of face recognition benchmarks have demonstrated the effectiveness of our method over state-of-the-art alternatives. Our source code is available at http://www.cbsr.ia.ac.cn/users/xiaobowang/. [ABSTRACT FROM AUTHOR]

A dual-transformer-based enhanced dual active bridge (DAB) dc–dc converter for wide voltage range applications is introduced in this article. A power leg and transformer of the conventional DAB converter (CDABC) are split in two parts, leading to an expansion of the control freedom. Its wide voltage operating range does not rely on the small leakage inductor design and high transformer turns ratio. The root mean square value of the leakage inductor current is optimized with the ensuring of full domain zero voltage switching. The conduction losses and switching losses can be significantly reduced in buck mode compared to the CDABC. A simple segment control strategy with four control degrees of freedom is employed to avoid inrush from mode switching. The analysis and control processes are simplified, and the control loop is a simple closed voltage loop without the need for look-up table checking. The discussed converter and control strategy are verified by a 1.0 kW prototype. [ABSTRACT FROM AUTHOR]

The emerging time-critical applications, such as industrial automation, smart grids, and telesurgery, pose strong demands for enabling end-to-end time-sensitive and deterministic networks. However, most of the existing research only considers the time-sensitive network in the layer 2 local area, or separately designs the deterministic network in the layer 3 wide area. The feasibility of end-to-end scheduling has been largely ignored. Moreover, the problem of multi-layer deterministic architecture design and cross-domain resource co-scheduling have not been fully considered. Therefore, this article proposes a novel architecture named C-TSDN, in which the cyclic queuing and forwarding mechanism and the cycle-specified queuing and forwarding mechanism are jointly designed to solve the bandwidth, cycle, and queue mismatch problems in end-to-end scheduling. The key functional modules of the proposed C-TSDN are detailed, including SRv6, network slicing, cycle alignment, and global computing. We elaborately exhibit the promising technical challenges, such as traffic analysis with AI. Finally, some potential open issues as future research directions are pointed out. [ABSTRACT FROM AUTHOR]

Pancreaticobiliary carcinomas is a highly malignant gastrointestinal tumor. Most pancreaticobiliary cancers arise from epithelial proliferation within the pancreaticobiliary ducts, referred to as pancreatic intraepithelial neoplasias (PanINs). Some PanINs are benign metaplasia, while others progress to invasive duct adenocarcinoma (IDAC). However, there is no standard program to diagnose the progression from PanINs to IDAC. In this study, we present a tri-modality imaging system, which integrates ultrasound (US), optical coherence tomography (OCT), and near-infrared fluorescence (NIRF) for pancreaticobiliary duct imaging. This system can obtain OCT, US, and NIRF images in real-time with a frame rate of 30 frames per second. For the endoscopy probe with an outer diameter of 0.9 mm, the US transducer and fiber ball lens were placed back to back. In vivo experiments were performed on the rectums of Sprague–Dawley rats to demonstrate the imaging performance of US, OCT, and fluorescence angiography. An ex vivo experiment on a human pancreatic duct was performed for a more accurate assessment of the pancreaticobiliary duct. The tomography images of rat rectums and human pancreatic ducts were correlated with hematoxylin and eosin (H&E) histology to check the measurement accuracy. The integrated tri-modality system has great clinical potential in mechanism studies, early diagnosis, and prognosis evaluation of malignant pancreaticobiliary carcinomas. [ABSTRACT FROM AUTHOR]

In-hand object localization and manipulation has always been a challenging task in robotic community. In this article, we address this problem by vision-based tactile sensing with high-spatial resolution. Specifically, we design a novel tactile sensor based on stereo vision, named GelStereo, which can perceive tactile point cloud with high-spatial resolution ($<\!1$ mm). A tactile-based in-hand object localization pipeline composed of saliency detection and probabilistic point-set registration algorithms of the perceived contact point cloud is presented. Furthermore, extensive qualitative and quantitative analyses of perceived tactile point cloud and in-hand localization and insertion experiments of small parts are performed on our robot platform. The experimental results verify the accuracy and robustness of the tactile point cloud sensed by the novel GelStereo tactile sensor and the proposed in-hand object localization pipeline. This novel high-resolution visuotactile sensing technology has predictable application potential in the field of dexterous robotic manipulation. [ABSTRACT FROM AUTHOR]

This article investigates the radiated electromagnetic interference (EMI) due to the voltage between input and output cables in a non-isolated power converter. The radiated EMI model of a non-isolated power converter is first developed and quantified based on the circuit topologies, printed circuit board (PCB) parasitics, switching waveforms, and transfer functions. Second, an antenna model is developed for converter cables based on the antenna impedance and the antenna transfer function. Third, a complete radiated EMI model is developed based on the converter's EMI model and the cable's antenna model. Fourth, the radiated EMI is analyzed based on the developed model. Finally, two radiated EMI noise reduction techniques, optimizing PCB layout and adding a cross capacitor, are proposed. The developed radiated EMI model and the proposed radiated EMI reduction techniques are verified with both simulations and experiments. The techniques are also extended to other two non-isolated power converter topologies when the radiated EMI is caused by the voltage between the input and output cables. [ABSTRACT FROM AUTHOR]

Robots have the potential to assist and complement humans in the exploration of hostile environments. For example, underwater vehicle–manipulator systems (UVMSs) have been researched and applied in underwater operations. Motivated by the need for collecting marine organisms cultivated in shallow sea aquafarm, a lightweight and portable UVMS propelled by flexible flippers (named, F-UVMS), rather than typical propellers or jet-based propulsion systems, is investigated. To this end, integrative mechatronic design of F-UVMS is first presented, involving six flipper propulsors for generating thrust in a flapping way, a four-degree-of-freedom arm for grasping, and a certain amount of onboard sensors for environment perception. A thrust–power measurement platform is established to evaluate thrust–power relationship for different sizes and stiffness of flippers. Meanwhile, the locomotion modalities of F-UVMS are analyzed. A framework based on the nonlinear model-predictive control method is implemented to govern autonomous tracking marine organisms. The capabilities of F-UVMS are validated through a series of experiments in laboratory pool and field missions in real sea conditions. [ABSTRACT FROM AUTHOR]

The concept of the more electric aircraft is aimed at electrifying the mechanical, hydraulic, and pneumatic subsystems on aircraft. With increasing usage of power electronics, the architecture of onboard electrical power distribution systems becomes more complicated. Therefore, it is necessary to analyze the stability of the system. This article, first, presents and validates an impedance model of a permanent magnet synchronous generator as a source and dual active bridge converter as a load. These models are used for the stability analysis of a simple dc power system. In addition, two new control strategies are proposed to enhance the stability of the system. The stabilization effects of the new control strategies are verified with experimental results. [ABSTRACT FROM AUTHOR]

Biomimetic underwater robots have attracted considerable research attention globally, owing to their quieter actuations, higher propulsion efficiency, and stronger maneuverability when compared with conventional underwater vehicles equipped with axial propellers. This article provides a comprehensive survey of current research in this field. First, we review the development status of biomimetic underwater robots in both body/caudal fin (BCF), median/paired fin (MPF), and their hybrid propulsion modes. Then, we outline the motion control methods employed in biomimetic underwater robots, including open-loop swimming control and typical closed-loop control strategies. In particular, we detail our latest studies on the RobCutt series underwater robots. On this basis, some critical issues and future directions are summarized. We predict that biomimetic underwater robots will have excellent prospects in underwater environment exploration and resource utilization. [ABSTRACT FROM AUTHOR]

This article develops magnetic dipole moment models based on Maxwell's equations for inductor's near magnetic field evaluation and reduction in power electronics systems. In the developed model, the near magnetic field source of an inductor is composed of the magnetic dipole moments from the winding and the air gaps. The superposition of the magnetic dipole moments determines the near magnetic field. The developed model can be easily applied to inductors with different winding and air gap configurations, such as those with lumped or distributed air gaps, for near magnetic field assessment and reduction. Simulations and experiments are conducted to validate the developed theory. [ABSTRACT FROM AUTHOR]

In this article, an efficiency-oriented control strategy is proposed for LCC–LCC-compensated wireless power transfer (WPT) system to achieve zero-voltage-switching (ZVS) operation over a wide current regulation range, in which full-bridge (FB) and half-bridge (HB) modes are combined and switchable based on requirements from load. The harmonic-considered time-domain models for FB and HB modes are first built to calculate current through the switches at the turn-off moment accurately. Then, focused on the constant voltage charge stage with variable output current, the ZVS boundaries are identified in HB and FB modes as the preferable control trajectories, which determines the desired current output with joint considerations of frequency, phase-shift angle, and duty ratio. Next, a least squares optimization method is introduced to fit the theoretical control trajectories into a smooth curve that is practical for implementation on microcontrollers. Finally, a 4.4-kW WPT prototype is built to verify the feasibility and validity of the proposed control strategy. Results show that a high system efficiency can be achieved over a wide output current range, with an efficiency of 94.68% even at 20% rated power. [ABSTRACT FROM AUTHOR]

A high switching frequency isolated voltage-fed dual-transformer-based hybrid semidual active bridge converter is introduced in this article for unidirectional power flow and wide voltage range applications. The converter embraces the full-bridge and half-bridge properties under varying operating conditions to improve efficiency. Five appropriate working patterns are elaborated, including ideal output power derivation, current stress analysis, working voltage matching, output power distribution, and soft switching features. Afterward, a simple segmented control strategy is adopted in accordance with the analysis results. The zero voltage switching of all switches is achieved by introducing the magnetic current and suitable drive logic. Compared with the existing works, the proposed converter has outstanding merits in terms of reduced conduction loss, switching loss, and peak current of ac inductor, resulting in high conversion efficiency. Hence, the converter is more suitable for cases with wide and frequent input voltage variations. Eventually, the effectiveness of the converter and the control strategy is verified by a 1.0-kW prototype. [ABSTRACT FROM AUTHOR]

A novel high switching frequency isolated voltage-fed hybrid bridge combining semiactive rectifier dc–dc converter is introduced for unidirectional power flow and wide voltage gain. Three potentially appropriate working patterns are elaborated, including ideal output power derivation, current stress analysis, working voltage matching, output power distribution, soft switching characteristics, etc. In consideration of the optimization of the minimum of the root-mean-square value of the leakage inductor current, two truly applicable working patterns are selected. Meanwhile, based on the consideration of soft switching, a segmented control strategy is implemented on it. With the optimization of current stress and the realization of soft switching, the converter can theoretically realize higher efficiency operation. Eventually, the effectiveness of the proposed converter and the control strategy is verified by a 1 kW prototype. [ABSTRACT FROM AUTHOR]

The drain to gate capacitance (Miller capacitance) of SiC MOSFETs leads to the Miller effect during switching transients. The Miller capacitance in a phase-leg configuration causes the crosstalk, the interaction between the two complementary switches, and the Miller plateau during the switching transient. The Miller effect reduces the switching speed, reduces reliability, and increases electromagnetic interference. In this article, by injecting a mirror cancellation current, the effects of Miller capacitance are canceled. The proposed technique includes a two-stage sensing and injection network to compensate for the nonlinearity of the Miller capacitance. The proposed technique can suppress both positive and negative gate voltage spikes induced by the crosstalk and reduce the switching power loss with the increased switching speed. Because no external control signals are required in the proposed technique, it can work with almost all commercial gate drivers. The detailed design for this proposed technique is presented in this article. The proposed technique was validated with both simulations and experiments. [ABSTRACT FROM AUTHOR]

Objective: In a few patients with mild COVID-19, there is a possibility of the infection becoming severe or critical in the future. This work aims to identify high-risk patients who have a high probability of changing from mild to critical COVID-19 (only account for 5% of cases). Methods: Using traditional convolutional neural networks for classification may not be suitable to identify this 5% of high risk patients from an entire dataset due to the highly imbalanced label distribution. To address this problem, we propose a Mix Contrast model, which matches original features with mixed features for contrastive learning. Three modules are proposed for training the model: 1) a cumulative learning strategy for synthesizing the mixed feature; 2) a commutative feature combination module for learning the commutative law of feature concatenation; 3) a united pairwise loss assigning adaptive weights for sample pairs with different class anchors based on their current optimization status. Results: We collect a multi-center computed tomography dataset including 918 confirmed COVID-19 patients from four hospitals and evaluate the proposed method on both the COVID-19 mild-to-critical prediction and COVID-19 diagnosis tasks. For mild-to-critical prediction, the experimental results show a recall of 0.80 and a specificity of 0.815. For diagnosis, the model shows comparable results with deep neural networks using a large dataset. Our method demonstrates improvements when the amount of training data is small or imbalanced. Significance: Identifying mild-to-critical COVID-19 patients is important for early prevention and personalized treatment planning. [ABSTRACT FROM AUTHOR]

This article presents a coordinated vehicle–manipulator control method for an underwater biomimetic vehicle–manipulator system (UBVMS) to implement floating autonomous manipulation in practice. An algorithm framework composed of adaptive tracking differentiator (ATD), extended state observer (ESO), improved nonsingular terminal sliding-mode control (I-NTSMC), fuzzy-logic controller (FLC), and estimator of manipulator disturbances, is proposed. The ATD is designed to generate desired motion state and alleviate noise. The ESO is developed to estimate the motion state, systematic uncertainties, and external disturbances. The proposed I-NTSMC method assures the finite-time convergence of the system states and alleviate chattering. The estimation of the manipulator disturbances is incorporated into the control strategy to enhance the station keeping of the vehicle. Finally, underwater autonomous free floating manipulation experiments about opening a door and grasping objects are conducted to validate the theoretical results and confirm the feasibility of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This article addresses a problem of seabed terrain following control (STFC) for an underwater vehicle-manipulator system (UVMS). The motivation is to perform a visual search of marine products closely to seabed in unknown environment. In terms of this issue, we propose a novel and robust STFC framework for our UVMS to maintain an appropriate height to seabed. A nonlinear model predictive control (NMPC) method is formulated to solve the STFC problem. To relieve online computational burden and system noisy influence, Ohtsuka’s continuation/generalized minimal residual (C/GMRES) algorithm incorporated with a tracking differentiator (TD) is investigated. In order to improve the following accuracy, the system state prediction part of the NMPC and a long short-term memory (LSTM) network are elaborated to predict future seabed terrain using a depth gauge and an altimeter, respectively. Finally, the three different physical scenarios for STFC problem are established using ROS to demonstrate the robustness and efficiency of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Converting random motion into directional motion of charged dust particles in plasma, i.e., the rectification, can be achieved by using a dusty plasma ratchet, in which the asymmetry of system plays a very important role. Here, we use different staggered angles between the inner and outer gears to control the asymmetry of system and further study experimentally the effect of the asymmetry induced by staggered angle on the rectification of dust particles in a dusty plasma ratchet. Our results show that the spatial distribution and the velocity of dust particles along the saw channel are nonuniform. Decreasing the asymmetry can reduce the flow of dust particle in the saw channel. [ABSTRACT FROM AUTHOR]

The vibration response of faulty bearing is always characterized by periodic transient impulses in the signal. Generally, these fault-related features are inevitably submerged in noise and harmonic components. Mathematical morphology is an excellent method of noise reduction, which can retain the detail information of impulses in the time domain. However, the filtering effect of traditional morphological operator (MO) might be easily affected by random impulses, and the proper selection of the structure element (SE) depends heavily on the experience of researchers. In order to effectively remove these interferences and extract the fault features accurately, an improved method, named adaptive morphological filter (AMF), is proposed in this article. This method utilizes autocorrelation to lift MO in time domain to enhance periodic components, and the scale of SE can, therefore, be calculated with the local maximum of the autocorrelation spectrum. Since the selection of the optimal SE scale is adaptive, researchers’ experience is no longer needed, and there is also no need to calculate the fault characteristic frequency (FCF) for the determination of maximum scale of SE. The vibration and acoustical signals of faulty locomotive wheel set bearing are analyzed with this method, and the results verify its effectiveness and ability. [ABSTRACT FROM AUTHOR]

In this study, a real-time underwater onboard vision sensing system is developed for robotic gripping. First, an efficient image enhancement method based on the Retinex theory is presented. The enhanced images are provided for underwater robot to observe the seabed environment clearly via cameras. Subsequently, a real-time lightweight object detector (RLOD) for the mobile embedded platform is proposed. The RLOD is designed as an hourglass detector network, which introduces dense connections and a featured pyramid network to improve the detection performance and speed. Moreover, from an engineering perspective, two merging methods are used to deploy the trained network. It can be implemented at 11.11 frames per second (FPS) on the Nvidia Jetson TX2 processor, satisfying the real-time requirement of underwater robotic gripping. Furthermore, a refraction tracing model is constructed. The comparative results show the effectiveness of the proposed methods. Finally, this onboard vision sensing system is mounted on an underwater robot with a manipulator to implement robotic gripping. Pool and sea experiments are conducted to verify the practicability of the developed system. [ABSTRACT FROM AUTHOR]

This article first developed an inductance model that includes the parasitic mutual inductance between parallel current path segments for SiC multichip power modules. Based on the developed model, the SiC multichip module's transient response was analyzed, important parasitic inductances were identified. The layout was improved based on the transient analysis. The improved package layout can reduce the parasitic inductance without increasing the fabrication difficulty. Experiments were conducted to validate the reduction of parasitic inductances. The parasitic ringing and the crosstalk effect were significantly reduced with the proposed technique. The thermal performance was also improved with the proposed layout. [ABSTRACT FROM AUTHOR]

This article first develops a radiated electromagnetic interference (EMI) model for a gallium nitride (GaN) integrated circuit (IC)-based active clamp flyback converter. Important capacitive couplings, which play a big role in the radiated EMI, are identified, extracted, and validated in the converter. The radiated EMI model is improved to characterize the impact of capacitive couplings. Based on the improved model, techniques to reduce capacitive couplings and the radiated EMI are proposed and experimentally validated. [ABSTRACT FROM AUTHOR]

In this article, a fast chance-constrained trajectory generation strategy incorporating convex optimization and convex approximation of chance constraints is designed so as to solve the unmanned vehicle path planning problem. A path-length-optimal unmanned vehicle trajectory optimization model is constructed with the consideration of the pitch angle constraint, the curvature radius constraint, the probabilistic control actuation constraint, and the probabilistic collision avoidance constraint. Subsequently, convexification technique is introduced to convert the nonlinear problem formulation into a convex form. To deal with the probabilistic constraints in the optimization model, convex approximation techniques are introduced such that the probabilistic constraints are replaced by deterministic ones while simultaneously preserving the convexity of the optimization model. Numerical results, obtained from a number of case studies, validate the effectiveness and reliability of the proposed approach. A number of comparative studies were also performed. The results confirm that the proposed design is able to produce more optimal flight paths and achieve enhanced computational performance than other chance-constrained optimization approaches investigated in this article. [ABSTRACT FROM AUTHOR]

This article proposes a concept for homothetic scaling of Synchronous Reluctance (SynRel) machines with the aim to generate a design for a wide range of power ratings. A generalized modeling approach, based on the saliency ratio, is presented in detail to analytically evaluate the magnetic behavior of the scaled SynRel machines. The analytical model has been applied to a wide range of machines and validated through finite element analysis. General scaling functions are derived to size and evaluate the performance of the scaled machines using the data resulting from the analytical model. The accuracy of the proposed functions is validated, for a range of operating conditions, comparing the results with the experimental measurement carried out on two 4-poles SynRel prototypes. These have been designed using the homothetic method proposed, which has been proven to be a quick and accurate preliminary sizing tool for SynRel motors. [ABSTRACT FROM AUTHOR]

Since wear particles usually contain valuable information about lubricant and wear condition of lubricated components, wear debris analysis is widely used to monitor machine/component wear. Current literature reports about the importance and necessity of 3-D surface characterization of wear particles as opposed to 2-D characterization. It may be borne in mind that traditional 3-D analysis has been a synonym only for local surface morphologies for stationary particles. This results in large errors when irregular particles are under observation. A new 3-D imaging methodology is proposed to reconstruct multiview 3-D surfaces for a moving particle whereby the target particle is passed through a microchannel with rolling motion, and recorded via a digital microscope. The multiple moving particles are tracked based on Kalman filter to obtain different-view images. Sparse and dense reconstruction of the particle surfaces are enabled by these images using Structure from Motion (SfM) and Shape from Shading (SfS) methodologies, respectively. The method was verified using real particles and evaluated by the results of laser scanning confocal microscopy. The proposed method is able to reconstruct wear particles under various perspectives, and the errors from the characterization parameters of the areal are less than 20 $\%$. [ABSTRACT FROM AUTHOR]

In this article, a low-frequency hybrid modulation technique which is composed of a phase shift-pulsewidth modulation (PS-PWM) and an asymmetric selective harmonic current mitigation-PWM (ASHCM-PWM) are proposed for cascaded multilevel converters to meet the harmonic limit of IEEE 519 2014. In the proposed technique, the harmonics within the concerned frequency range due to PS-PWM are reduced by the ASHCM-PWM so that the cascaded H-bridge (CHB) converter can meet IEEE 519 harmonic limit. The equation set which helps a grid-tied CHB converter meet both harmonic limit and total demand distortion, is developed. The design technique for critical parameters, such as the inductance and the switching frequency of the proposed hybrid modulation technique, is developed. Simulation and experiments are conducted on a single-phase 3-cell 7-level grid-tied CHB converter to validate the proposed technique. [ABSTRACT FROM AUTHOR]

This article presents the innovative control scheme of renewable ancillary services to support the system operation of a bulk power system with high penetration of renewable energy. The smart inverters of PV systems can be controlled to adjust the renewable generation of real and reactive power according to the variation of system voltage and frequency. The dispatch control of renewable ancillary services is integrated with the energy management system to achieve the coordination control of renewable energy and synchronous generators. The sensitivity factors of renewable system was applied to determine the generation curtailment for the mitigation of line overloading. The ancillary service of reactive power compensation by renewable energy was considered to improve the system voltage quality. The emergency generation control of renewable systems with fast ramping up capability was applied to illustrate the effectiveness of renewable ancillary service to improve the system frequency response after sudden generator tripping. Based on the computer simulation of an actual power system with large renewable energy to be integrated, the functions of virtual synchronous generators by the photovoltaic systems and wind farms have to be applied to ensure the successful steady-state operation and to improve the system transient stability for severe disturbance contingency. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present an approximation-based strategy for solving the problem of nonlinear trajectory optimization with the consideration of probabilistic constraints. The proposed method defines a smooth and differentiable function to replace probabilistic constraints by the deterministic ones, thereby converting the chance-constrained trajectory optimization model into a parametric nonlinear programming model. In addition, it is proved that the approximation function and the corresponding approximation set will converge to that of the original problem. Furthermore, the optimal solution of the approximated model is ensured to converge to the optimal solution of the original problem. Numerical results, obtained from a new chance-constrained space vehicle trajectory optimization model and a 3-D unmanned vehicle trajectory smoothing problem, verify the feasibility and effectiveness of the proposed approach. Comparative studies were also carried out to show the proposed design can yield good performance and outperform other typical chance-constrained optimization techniques investigated in this paper. [ABSTRACT FROM AUTHOR]

Virtual synchronous control (VSynC) in DFIG -based wind turbines (WTs) was studied. It utilizes its relatively “slow” inner potential to enhance the WT's dynamic frequency support capability. However, this will pose more severe challenges on the VSynC-based DFIG under symmetrical grid faults than the conventional vector current controlled one. This article mainly studies the fault ride through strategy of the VSynC-based DFIG under symmetrical grid fault. The fault current is limited and the dynamic reactive power support to help grid voltage recovery are studied. Firstly, the transient behavior of the VSynC-based DFIG is analyzed and the influence of the originally existing virtual resistance is studied. In the proposed method, the virtual resistance just works in the forced current component to limit the forced component of the fault current and accelerate the attenuation of the natural flux. Then the dynamic feedforward compensation is employed to trade-off to limit the natural component of the fault current and decay the natural flux component aroused by grid faults. In addition, the fast dynamic reactive power support of during grid faults according to grid codes. On the post-fault, the coordination control of active power is also implemented to limit steady-state rotor current. Finally, simulation and experiment results demonstrate the feasibility and correctness of the proposed fault ride through strategy for the VSynC. [ABSTRACT FROM AUTHOR]

This article presents the design of a biomimetic underwater vehicle-manipulator system (BUVMS) with bioinspired long-fin propulsion and its control methods. The kinematic analysis of bioinspired long-fin propulsion is conducted, and the maximum thrust of this propulsion derived from our thrust measurement platform can be up to 25 N. Bioinspired long-fin propulsion is introduced to construct the BUVMS for inspection and manipulation tasks, and the system architecture of the BUVMS is described. Moreover, real-time dynamic dubins-helix path planning and tracking of the biomimetic vehicle are proposed to realize the arrival of the desired pose. The tracking error is less than 0.23 body length. Finally, coordinated control between the biomimetic vehicle and the manipulator is developed to achieve autonomous manipulation. The reaction of the manipulator served as feedforward compensation is added into the closed-loop control of the biomimetic vehicle. The experimental results are provided to illustrate the validity of the proposed methods. [ABSTRACT FROM AUTHOR]

In this article, the effects of the parameters of GaN HEMTs and Si mosfets and the load conditions on the radiated electromagnetic interference (EMI) are analyzed based on the compositions of the equivalent noise voltage sources. These compositions include the rising and falling edges of the switching voltages, the zero-voltage-switching voltage drops and the parasitic ringing. The radiated EMI from two identical dual-active bridge converters with GaN HEMTs and Si mosfets is investigated and compared. Experiments were conducted to validate the analysis. [ABSTRACT FROM AUTHOR]

Optical multipath RF self-interference cancellation (SIC) based on phase modulation for full-duplex communication is proposed and demonstrated experimentally. Phase modulation is utilized to convert the RF signal into optical domain, in which the time delay tuning, amplitude tuning and phase inversion for multipath RF SIC are completed. The comprehensive theoretical model of the optical multipath RF SIC system is established, and the factors affecting SIC performance including the time delay, amplitude and phase deviations are analyzed. The experimental results verify the feasibility of the proposed scheme for full-duplex communication with the cancellation depth of 26 dB and 28 dB over 100 MHz at central frequency of 6 GHz and 10 GHz, respectively. A figure of merit of the maximum interference to signal of interest ratio is defined to characterize the SOI recovery capability of optical RF SIC system. [ABSTRACT FROM AUTHOR]

In consumer electronics, high power density power adapters are designed to minimize the adapter size. As a result, the components are getting very close and the near-field coupling issue tends to be severe. This compromises the performance of electromagnetic interference filters, especially at high frequencies. This article investigates near-field capacitive couplings and the reduction techniques in a high power-density power adapter with a dc-bus filter. The parasitic capacitive coupling theory is developed and parasitic coupling capacitances are experimentally extracted. The common-mode (CM) noise model with parasitic capacitive couplings is developed and the techniques to reduce the CM noise due to parasitic capacitive couplings are explored. Simulation and experiments were conducted to verify the analysis and the proposed techniques. [ABSTRACT FROM AUTHOR]

In this article, the common-mode (CM) noise model is developed for an ac–dc–ac system with paralleled power modules. The CM noise contributions from both rectifiers and motor drives are analyzed. The interaction between the ac/dc rectifiers and dc/ac motor drives is explored. The CM noise reduction techniques which include a decoupling inductor technique and a CM noise balance technique are proposed to reduce the CM noise on the ac input side. Experiments and simulations were conducted to validate the developed CM noise model, rectifier and inverter interaction theory and CM noise reduction techniques. [ABSTRACT FROM AUTHOR]