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SiC JFET bi-directional switches (BDS) are widely used in construction of matrix converters, multi-level converters, solid state switches, etc. In this research work, the phenomenon of unwanted turn-on (UTO) of SiC JFET-based BDS and its related constant envelop oscillation is investigated. This phenomenon is critical to power conversion systems' stability and reliability. Firstly, the roots of UTO...
The well-known maximum torque per ampere (MTPA) strategy is usually integrated the field oriented control (FOC) to improve the efficiency of interior permanent-magnet (IPM) synchronous motor drives. As an alternative to the FOC, direct torque control (DTC) has attracted extensive attention from both academia and industry in the last few decades, due to its distinctive advantages, e.g., fast dynamic...
The photovoltaic (PV) source simulators are widely used to test solar inverters, evaluate their control algorithms and study their grid integration issues in the laboratory settings. Many commercial programmable dc power supplies can be re-programed to be PV simulators. Due to the bulky output dc capacitors, the dynamic response and the bandwidth of these PV simulators are significantly limited, which,...
The existing localization methods for the satellite communication interference source based on satellites are too complex and costly to be used in practical applications. A new localization method based on two satellites for the interference source is proposed in this paper. By combining two localization parameters named time difference of arrival (TDOA) between two satellites and the direction of...
Detecting actions in untrimmed videos is an important yet challenging task. In this paper, we present the structured segment network (SSN), a novel framework which models the temporal structure of each action instance via a structured temporal pyramid. On top of the pyramid, we further introduce a decomposed discriminative model comprising two classifiers, respectively for classifying actions and...
A novel structure of meta-surface with the function of high gain polarization conversion is proposed and studied. The meta-surface consists of 16 radiating elements, which are 4×4 periodically arranged under the Rogers substrate. In this paper, the high gain and radiation conversion mechanism of meta-surface are analyzed from the aspects of transmission phase and transmission amplitude of the microwave...
Cloud computing data centers have become one of the most important infrastructures in the big-data era. When considering the security of data centers, distributed denial of service (DDoS) attacks are one of the most serious problems. Here we consider DDoS attacks leveraging TCP traffic, which are increasingly rampant but are difficult to detect. To detect DDoS attacks, we identify two attack modes:...
In this work, we conduct a systematic exploration on the promise and challenges of deep learning for the sparse matrix format selection. We propose a set of novel techniques to solve special challenges to deep learning, including input matrix representations, a late-merging deep neural network structure design, and the use of transfer learning to alleviate cross-architecture portability issues.
Beamforming is a signal processing technique in which multiple antennas are used to weight the signals so that they can be added constructively in the desired direction, and destructively in the interference direction. In this paper, adaptive beamforming based on subband decomposition structure is investigated in smart antenna arrays and the performance of the proposed adaptive beamforming scheme...
Adaptive beamforming plays an important role in smart antenna systems. Nonblind adaptive algorithm utilizes the known training sequence to update the weights of antenna array at the cost of low transmission efficiency. Without sending training sequences, blind adaptive algorithm is a solution to implement beamforming and increase the transmission efficiency. Two classic blind algorithms are studied,...
A new ground moving target indication algorithm for single channel Circular Synthetic Aperture Radar (CSAR) is presented and evaluated by airborne CSAR dataset. The algorithm is based on overlap subaperture magnitude images. The subaperture image can be regarded as the background image (clutter) plus the foreground image (moving target). The background image is obtained by median filter. Then the...
The cospark of a matrix is the cardinality of the sparsest vector in the column space of the matrix. Computing the cospark of a matrix is well known to be an NP hard problem. Given the sparsity pattern (i.e., the locations of the non-zero entries) of a matrix, if the non-zero entries are drawn from independently distributed continuous probability distributions, it is shown that the cospark equals,...
Electromagnetic interference (EMI) suppression becomes more and more prominent in the design of electronic systems, especially in the design of modular systems. An advanced EMI suppression approach for modular systems is proposed in this paper. In this approach, the output spectrum of a system or a module is analyzed and decomposed into several types which are called elements in this paper. Each element...
DC Microgrids (DC MG) present themselves as an obvious choice enabling integration of multiple renewable energy sources and distributed energy storage. This concept of DC electrification of homes in small communities is being explored in many parts of the world. Furthermore, typical household loads are increasingly becoming natively DC. In this paper, a community DC MG in an urban environment is analyzed...
We focus on the 3-dimensional (3D) source localization passively by using TDOA and AOA in the presence of sensor errors. Determining the position from the TDOA and AOA measurements is not an easy task because the relationship between them is nonlinear. We present a new WLS solution that the TDOA equation is simpler than relevant literature (Yin and Wan, A Simple and Accurate TDOA-AOA Localization...
For Qball-X4 four-rotor unmanned aircraft with its own characteristics, creating nonlinear model of system and adopting double closed-loop control algorithm with inner and outer loop are controlled by attitude and position respectively. Linear quadratic regulator is easy to solve state feedback control rate quickly, and has good robustness, thus LQR is utilized to design attitude inner loop controller...
This paper compares multiple loop-shaping combined robust control methodologies including Glover-McFarlane method, H ∞ and H2 in the controller synthesis of track-following application for hard disk drive (HDD). According to the specified loop-shaping goal, the synthesis routines are applied on the Spinstand micro-actuator in order to achieve robust performance in terms of system uncertainties accommodation,...
Aggregating statistically diverse renewable power producers (RPPs) is an effective way to reduce the uncertainty of the RPPs. The key question in aggregation of RPPs is how to allocate payoffs among the RPPs. In this paper, a payoff allocation mechanism (PAM) with a simple closed-form expression is proposed: It achieves stability (in the core) and fairness both in the “ex-post” sense, i.e., for all...
Power grid scale is expanding, more generators with large capacity are used in the power system, the growth of the load current is rapidly, the realization of the major regional power grid interconnection, all of these factors will lead to the fault current level continues to rise, which may lead to serious security problems, even collapse and collapse of the system. This paper proposes a high-speed...
The paper studies the rapid identification technology of short circuit fault and the predictive technology of the time at which the fault current is zero, introduces the current signal can be used for processing cycle of the half-wave Fourier algorithm, improves the algorithm according to the features of short circuit current and the inherent defects of half-wave Fourier algorithm and verifies the...
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