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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Liu, Xiaobo Rong, Cancan Tao, Xiong Lu, Conghui Zeng, Yinqing Liu, Renzhe Liu, Minghai Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781728196596

Stable and high-efficiency transmission performance is of great significance for wireless power transfer (WPT) system. Despite of some approaches, such as improving the quality factor (Q), regulating current distribution and achieving the impedance matching, can minimize the unfavorable influence and improve the system performance, the uniformity of electromagnetic field need further consideration. This paper proposes a modified spatial tri-axial circular Helmholtz coil (MTHC) to shape the homogeneous magnetic field over a large range in the three-dimensional direction of space so as to improve the flexibility of receiving coil position. The designed MTHC coil is to add a pair of compensation coils on each dimension. And the structural characteristics of the traditional Helmholtz coil, the improved compensated Helmholtz coil, and the spatial Tri-axial circular helmholtz coil are analyzed through theory and simulation, results show that the traditional Helmholtz coil structure has a uniform magnetic field area on the coaxial axis, but the uniform magnetic field area is small;the improved four-coil Helmholtz structure increases the uniform magnetic field area on the coaxial axis;the designed spatial Tri-axial circular Helmholtz coil structure is in the three-dimensional direction generating a wide uniform magnetic field. © 2020 IEEE.

关键词： Energy transfer

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Mitral Regurgitation Recognition based on Unsupervised Out-of-Distribution Detection with Residual Diffusion Amplification

arXiv

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arXiv 2024年

作者： Liu, Zhe Zhu, Xiliang Han, Tong Huang, Yuhao Wang, Jian Liu, Lian Wang, Fang Ni, Dong Gou, Zhongshan Yang, Xin National-Regional Key Technology Engineering Laboratory for Medical Ultrasound School of Biomedical Engineering Medical School Shenzhen University China Lab Shenzhen University China Key Laboratory for Bio-Electromagnetic Environment and Advanced Medical Theranostics School of Biomedical Engineering and Informatics Nanjing Medical University China Shenzhen RayShape Medical Technology Co. Ltd China Center for Cardiovascular Disease The Affiliated Suzhou Hospital of Nanjing Medical University China

Mitral regurgitation (MR) is a serious heart valve disease. Early and accurate diagnosis of MR via ultrasound video is critical for timely clinical decision-making and surgical intervention. However, manual MR diagnosis heavily relies on the operator’s experience, which may cause misdiagnosis and inter-observer variability. Since MR data is limited and has large intra-class variability, we propose an unsupervised out-of-distribution (OOD) detection method to identify MR rather than building a deep classifier. To our knowledge, we are the first to explore OOD in MR ultrasound videos. Our method consists of a feature extractor, a feature reconstruction model, and a residual accumulation amplification algorithm. The feature extractor obtains features from the video clips and feeds them into the feature reconstruction model to restore the original features. The residual accumulation amplification algorithm then iteratively performs noise feature reconstruction, amplifying the reconstructed error of OOD features. This algorithm is straightforward yet efficient and can seamlessly integrate as a plug-and-play component in reconstruction-based OOD detection methods. We validated the proposed method on a large ultrasound dataset containing 893 non-MR and 267 MR videos. Experimental results show that our OOD detection method can effectively identify MR samples. Copyright © 2024, The Authors. All rights reserved.

关键词： Diagnosis

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Design of a combined-function corrector for HUST FEL-THz 1

Design of a combined-function corrector for HUST FEL-THz

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Jiang, Kunyue Fan, Kuanjun Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781728196596

Free electron laser Terahertz source (FEL-THz) has significant advantages, such as wide and continuously adjustable spectrums. A compact terahertz source is desired to reduce the cost and space but still provide high-quality terahertz beams. However, the space constraints requires all the magnets should be downscaled as well. In this paper, a combined-function corrector is designed, capable of providing vertical and horizontal correction at the same time. Poisson and Opera-3D have been used to design and optimize the magnet. The vertical correction is mainly performed by shimming and trimming the magnetic pole head, and the horizontal correction is mainly performed by adjusting the current coil. As a result, the good field range of the vertical field and the horizontal field reach the expected value, and the relative error of the integrated field meets the requirements of beam correction. © 2020 IEEE.

关键词： Free electron lasers

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Current sharing structure analysis and design of high-current thyristor converters based on PEEC method 1

Current sharing structure analysis and design of high-curren...

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Dong, Kehong Yang, Yong Song, Zhiquan Zhang, Ming Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781728196596

Current sharing among multi-parallel thyristors is a key task in the design of high-current converters. However, conventional current sharing methods seldom consider the stray inductance which acts a significant role in the current sharing. This paper mainly focuses on stray inductance, and builds a current sharing equation based on Partial Element Equivalent Circuit (PEEC) method for the current sharing analysis and design of high-current converters. The deduction of the equation is presented. As an example, the application of the proposed method in the design of the International Thermonuclear Experimental Reactor (ITER) Poloidal Field Converter Unit (PFCU) is briefly presented. The current sharing coefficient is over 0.8, which is greatly improved and beyond the required value. The method proposed in this paper can be used for the fast design of the physical layout of a converter, and further improve its current sharing along with conventional design methods. © 2020 IEEE.

关键词： Thyristors

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A nonzero vector PWM method to reduce common-mode voltage 1

A nonzero vector PWM method to reduce common-mode voltage

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Gao, Xuepeng Kong, Wubin Qu, Ronghai Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781728196596

The common-mode voltage in three-phase inverter may harm the motor drive system. If only non-zero space vector is used, it can be suppressed by appropriate Space Vector Pulse Width Modulation (SVPWM) method. In this paper, a Nonzero Vector Pulse Width Modulation (NZPWM) technique is proposed to suppress common-mode voltage for three-phase inverter. In sectors I, III and V, instead of the real zero voltage vectors, two opposite voltage vectors near to the active voltage vectors are utilized. In sectors II, IV and VI, the first active voltage vector and the voltage vector opposite to the first active voltage vector are utilized. Therefore, the amplitude of common-mode voltage can be reduced to one sixth of DC bus voltage. Simulation and experimental results show that the proposed NZPWM is effective for common-mode voltage suppression. © 2020 IEEE.

关键词： Pulse width modulation

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Ozone emission and electric characters of wire-plate corona discharge 1

Ozone emission and electric characters of wire-plate corona ...

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Hu, Yehong Yang, Yong Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781728196596

Ozone emission of corona discharge has been studied for many years. We use Differential Optical Absorption Spectroscopy (DOAS) to build an optical detection system with a limit of 465 ppm and precision of 0.01 ppm to detect the ozone concentration, on this basis, we investigated the effect of voltage, materials, number of electrodes and gas flow on ozone emission. Compared with the negative corona discharge, positive corona produces a small amount of ozone at the same voltage, and more ozone is produced in positive pulse than that in positive DC. The electrode materials do not change the current-voltage characteristics of corona discharge, but silver and copper significantly reduce ozone production. The number of electrodes affects the electric field distribution thus the electron density is changed. At the same current, the more electrodes, the less ozone is generated. With the increase of gas flow, the ozone concentration decreases and reaches saturation concentration within a shorter time. © 2020 IEEE.

关键词： Electrodes

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Suppression Effect of TCSC on sub-synchronous oscillation of grid integrated DFIG 1

Suppression Effect of TCSC on sub-synchronous oscillation of...

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Wu, Sicheng Sun, Haishun Han, Yingsheng Huang, Biyue Mao, Yujie School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9781728196596

Wind power resources are remotely distributed in China. The fixed series compensation (FSC) is one of the traditional methods to solve the problem of long-distance power transmission of the doubly-fed induction generators (DFIGs) based wind farm. The introduction of FSC will bring potential sub-synchronous oscillation (SSO) risks to the power system. With the development of flexible AC transmission system (FACTS), thyristor-controlled series compensation (TCSC) has become an effective substitute for FSC due to its suppression effect on sub-synchronous oscillation. This paper mainly studied the natural and active suppression effect of TCSC on sub-synchronous oscillation of grid integrated DFIG. Based on the frequency scanning method, the impedance characteristics of TCSC and DFIG were obtained to study the natural suppression effect of TCSC, and some key parameters were discussed. However, when the system was particularly weak, the natural suppression might not keep the system stable. Thus, an additional sub-synchronous oscillation damping control (SSDC) was proposed as active suppression of TCSC, which could further enhance the stability of system. The frequency scanning results showed that the SSDC could effectively improve system stability. Finally, the electromagnetic transient simulation results in PSCAD/EMTDC verified the above conclusions. © 2020 IEEE.

关键词： Flexible AC transmission systems

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Selective harmonic elimination control for cascaded digital power amplifier 1

Selective harmonic elimination control for cascaded digital ...

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Tu, Junyao Liu, Hengyang Kong, Wubin State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781728196596

In this paper, the selective harmonic elimination (SHE) strategy for cascaded digital power amplifier is derived and proposed. To solve the problem of slow iteration speed or even non-convergence of the traditional iterative method when the number of levels or the number of harmonic elimination equations is large, a new solution method based on "interior point method"is introduced. In practical application the dead-time cannot be avoided, so the impact of dead-time on selective harmonic elimination strategy is also analyzed. Based on the relationship between output voltage and current during dead-time, the control method of "flexible insertion of dead-time on line"is proposed, which can significantly weaken the dead-time effect on selective harmonic elimination strategy in practice. © 2020 IEEE.

关键词： Iterative methods

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Optimized electro-optical detection system for a FEL-THz source 1

Optimized electro-optical detection system for a FEL-THz sou...

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Wang, Lei Tu, Xiude He, Sijing Xiong, Yongqian Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781728196596

A detection system based on electro-optical(EO) sampling is designed for the established high-power, wide-band and wave-tunable FEL-THz source at Huazhong University of Science and technology (HUST). The phase mismatch and dispersion propagation of the femtosecond laser pulse in the crystal are the main reasons that cause the distortion of the EO signal. We theoretically calculate and analyze the mixing process of the probe pulse and THz pulse in the crystal. Calculating the coherence length to find the suitable center wavelength probe for different detected crystals (ZnTe, Gap, GaAs). In addition, our simulation results show that the broadband laser can eliminate the effect caused by phase mismatch between the THz phase velocity and the group velocity of the laser in different crystals (ZnTe, Gap, GaAs). Moreover, the experiment results of 3-mm-thick ZnTe with sampling laser of 100nm bandwidth agree the simulation results well. The research is meaningful for optimizing the EO sampling system in the future. © 2020 IEEE.

关键词： III-V semiconductors

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Effect of high-speed train on vibration and fatigue life of transmission lines 1

Effect of high-speed train on vibration and fatigue life of ...

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Yin, Ming Guo, Yizhong He, Zhenghao Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781728196596

There are frequent reports of cable rupture accidents on the transmission line crossing high-speed railways. A simulation method for dynamic response and fatigue life of transmission lines considering natural wind and train induced wind is presented and verified by field tests. Based on a case study, the displacement time history and fatigue damage of conductors under wind loads are analyzed, and the effects of different parameters are discussed. The results show that the fatigue damage caused by train induced wind can reach 127% of natural wind, and its influence on the fatigue life of transmission lines cannot be ignored. Raising height or avoiding the most unfavorable span length can effectively reduce the influence of train induced wind. The proposed method can be used for the structural design and safety assessment of transmission lines crossing the high-speed railway, and it can provide references to the design of damping devices. © 2020 IEEE.

关键词： Electric lines

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