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Image compression plays more and more important role in image processing. Image sparse coding with learned over-complete dictionaries shows promising results on image compression by representing images with dictionary atoms compactly. Within the sparse coding based compression framework, a sparse dictionary is first learned from training images in a predefined image library, and then an image is compressed...
DC arc characteristics • V-I equation modeling • High frequency noise modeling DC arc fault detection • Signatures from both time and time-frequency domain • Detection algorithm, implementation, and verification System level dc arc fault protection • DC arc faults in arbitrary locations • Fault responses and detection algorithm development • Interaction between protection and control.
Modular multilevel converters (MMCs), with the filter-less and transformer-less features, are considered as a promising topology for high-efficiency medium voltage (MV) high voltage (HV) drive systems. However, at low frequencies (< 30 Hz), a large current ripple flowing through the capacitors of each submodule will cause significant capacitor voltage fluctuation. This paper proposes an optimal...
Dc arc faults may result in serious damage to both stationary and mobile dc power systems. This paper presents a new detection method for dc arcs using Hurst exponents. Compared to other methods such as the Fast Fourier Transform (FFT) and the Wavelet Transform, the proposed method is adaptive and is more immune to power electronics switching harmonics. A test setup to generate dc arcs is built and...
This paper proposes an Active Gate Current Control (AGCC) strategy for non-insulating gate WBG devices, for example, gallium nitride gate-injection-transistor (GaN-GIT) and silicon carbide super junction transistor (SiC-SJT). It provides a tool for power converter designers to further improve the converter efficiency and to extend the life time of those higher cost power transistors. By continuously...
The emerging 650 V large current rating, Enhancement-mode (E-mode) Gallium Nitride High-Electron-Mobility Transistor (GaN HEMT) is a promising device for low to medium power, high power density converters (e.g., motor drives, battery chargers), which require high robustness levels. Thus, a comprehensive study of the short circuit behavior of high power E-mode GaN HEMT is the subject of this paper...
Application areas such as electric vehicles, data centers and microgrids increasingly rely on power electronic converters and electric motor drives to control loads. These tightly regulated converters act as Constant Power Loads (CPLs) in the context of the entire system. The negative incremental impedance of a CPL causes inherent instability which may lead to a grid collapse. This paper reviews the...
Silicon Carbide (SiC) power devices with super-cascode structure provide a cost-effective solution for high performance medium voltage power switches. However, these SiC super-cascode devices are still in the early development stage, and limited information on the device characteristics is available. This paper presents the characterization and evaluation of a 4.5 kV, 40 A SiC super-cascode device...
With the rapid development of the wide bandgap (WBG) power transistor technology, the latest Silicon-Carbide and Gallium-Nitride (SiC and GaN) based power transistors can be used as the main switches in the medium power (≥10 kW) conversion systems. Electrical signal based efficiency measurement could be very challenging due to the high-frequency output signals and the high power to loss ratio. In...
This paper presents an evaluation of a newly released power stage direct drive GaN HEMT. The double pulse test is performed and the dynamic performance is characterized. PCB layout optimization is also investigated for improved switching transients. It is shown that the direct drive system provides simplified circuit design, reduced number of external components, and small gate loop parasitics. Also,...
In order to improve the tracking accuracy and the scheduling success rate on the problem of phased array radar task scheduling. Adaptive time window is proposed to solve this problem. Firstly, the target state for the next observation is predicted and the influence of time shifting is sought out. Then, the size of the time window is calculated according to the influence. Finally, the simulation is...
In this paper, a novel Fuzzy Sliding Mode Control (FSMC) method is proposed to solve destabilization because of high nonlinear characteristics and parameter uncertainty of distributed drive electric vehicle when turning or changing lanes at high speed. First, 2-DOF dynamic model is built up in order to deduce the desired yaw rate and desired slip angle. Then, the Direct Yaw-moment Controller is designed...
Nowadays, more and more methods have been proposed to solve the problem of face detection based on computer implementation. Due to the variations in background, illumination, pose and facial expressions, the problem of machine face detection is complex. Recently, deep learning approaches achieve an impressive performance on face detection. In this paper, a model named Multi-Scale Fusion Convolutional...
Mutual information (MI) and transfer entropy (TE) are employed to measure correlation and interdependence between stocks. Based on algorithms of Minimal Spanning Tree (MST) and Planar Maximally Filtered Graph (PMFG), redundant information contained in fully connected networks represented by MI and TE matrices are filtered and according networks are constructed. It is found that the MST of MI constructed...
This paper aims to employ a fuzzy decision-making approach to evaluate risk control options and aid the selection of operational safety strategies in container terminals. The selection of appropriate safety strategies to optimize the Operational Safety Performance (OSP) in container terminals has been a key strategic consideration for many maritime stakeholders including terminal managers, ship-owners,...
Human failure is one of the dominant causes of maritime accidents. However, the relationship between seafarers' operations and mental workload remains largely unclear. It is meaningful to investigate it based on the analysis of seafarers' physiological data when on duty. For this purpose, a preliminary study on this subject is carried out. Research techniques of human factors related to neurophysiological...
The single-phase line-start synchronous reluctance motor (LSSynRM) is suitable for household appliances, but an optimized design of rotor, crucially influences the performance of motor, is hard to obtain. This paper optimizes the rotor design of LSSynRM to make a higher saliency ratio with the trade-off between saliency ratio and synchronizing ability. The mechanical-field-circuit coupled Finite element...
A novel two-speed line-start permanent magnet motor (TSLSPMM) is proposed to replace the traditional pole-changing two-speed induction motor for energy saving. The proposed TSLSPMM, featured with pole-changing stator winding and a squirrel cage rotor with fixed permanent magnet poles, starts by a winding connection with higher pole number, and runs as an induction motor for a period of time, and after...
The canned solid-rotor induction motors with squirrel-cage (CSRIMSC) are widely used in petroleum, chemical and pharmaceutical fields. The equivalent circuit of the conventional induction motor is not suitable for CSRIMSC due to the special structure. In this paper, an analytical method of performance calculation for CSRIMSC is proposed. The effects of solid rotor and cans are considered. Besides,...
We take this opportunity to introduce our research and development effort on MEMS-based dynamic x-ray optics that exploit the properties to manipulate and control the x-ray pulses at synchrotron sources for time-resolved experiments.
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