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advanced Electrical Equipment and Reliable Operation (AEERO), International Conference on

作者： Qiaobo Xiong Yawei Wang Qing Liu Chunqing Xiang Dezhi Xia Laboratory of Low frequency Electromagnetic Communication Technology with the 722 Research Institute CSSC Wuhan China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781665402651

the space charge generate by the corona discharge near the UHVDC overhead transmission lines can distort the electric field distribution under thunderstorms. this paper presents a numerical model to estimate the corona space charge produced by horizontal conductors in response the electric field generated by both thundercloud and downward leader. Secondly, the corona space charge development process from ground conductors was obtained. The transition process of corona discharge to subsequent streamer is analyzed. the inhibition effect of the space charge layer on the subsequent streamer initiation was calculated by considering different conductor diameters. It is concluded that there is an optimal diameter for horizontal conductors which can ensure a superior capability to launch subsequent streamers, which should achieve a corona-free condition under the electric field of thundercloud.

关键词： Surface waves Surface discharges Lightning Space charge Fault location Conductors Corona

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The $\alpha\beta$ Impedance Modeling with Small Disturbances of Any Form for Three-phase Power-Electronics-Based Power Systems

The $\alpha\beta$ Impedance Modeling with Small Disturbances...

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Electrical engineering and Control Technologies (CEECT), Conference on

作者： Ziqian Yang Yifan Huang Meng Zhan State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

Many methods have been proposed for small-signal stability analysis of power-electronic-based power systems. As one common method, the sequence impedance model stands on that the disturbances are in the form of harmonics, which seems not consistent with the basic small-signal stability theory. In this paper, firstly small disturbances of any forms are applied to the three-phase voltage. By a rigorous Laplace transform, the $\alpha\beta$ impedance of the power electronic device is obtained, both in the form of transfer function matrix and complex transfer function. Then, the equivalence between the proposed model, the sequence impedance model, and the complex transfer function model are obtained. Finally, the open-loop response of a voltage source converter (VSC) and the stability of its grid connected system are verified by simulation. Based on the detailed analysis in the paper, it has been proved that the sequence impedance model is suitable for small-signal stability analysis of power-electronic-based power systems under not only harmonic disturbances but also any forms of disturbances, standing on a more rigorous mathematical basis.

关键词： Analytical models Transfer functions Voltage Power system stability Power system harmonics Harmonic analysis Mathematical models

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Characterization of the High Graded Magnetic Material based Linear Generator for Wave Energy Conversion 13

Characterization of the High Graded Magnetic Material based ...

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13th International Symposium on Linear Drives for Industry Applications, LDIA 2021

作者： Molla, Selim Farrok, Omar Islam, Md. Rabiul Xu, Wei Department of Electrical and Electronic Engineering Ahsanullah University of Science and Technology Dhaka1208 Bangladesh School of Elect. Comput. and Telecommun. Eng. University of Wollongong WollongongNSW2522 Australia State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781728172101

Characterization of a permanent magnet linear generator (PMLG) for harvesting oceanic wave energy is presented in this paper. For the characterization, a PMLG has been designed which has a translator containing permanent magnet and vertically symmetric stator. Different high graded magnetic materials are applied to the PMLG to generate high amount of electrical power. As a part of characterization, load profile is analyzed to determine its peak generated power for each of the magnetic materials. Comparison of generated voltage, generated voltage, load current, output power, and magnetic flux linkage of the PMLG are presented in detail. Translator force and velocity are determined to calculate the efficiency of the PMLG. The analysis is performed with finite element method by using ANSYS/Maxwell software. Armature reaction, demagnetization, and core loss that occurs in the PMLG are considered for the analysis. © 2021 IEEE

关键词： Permanent magnets

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Sc-Doping in Na3zr2si2po12 Electrolytes Enable Preeminent Performance of Solid-State Sodium Batteries in a Wide Temperature Range

SSRN

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SSRN 2022年

作者： Wang, Qiao Yu, Chuang Li, Liping Liu, Xiaoqing Zhang, Xin Gao, Guichen Wang, Yaowen Li, Guangshe State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun130012 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430000 China

Solid-state sodium batteries (SSSBs) display great potential in scale energy storage for their safety, cost and sustainability. However, it is a great challenge to achieve high ionic conductivity and temperature adaptability for most sodium-ion solid electrolytes. Here, we demonstrate that Sc 3+ -doped Na 3 Zr 2 Si 2 PO 12 (NASICON) is a promising electrolyte for a wide temperature range utilizing in SSSBs from 0 to 50 °C. Optimal Na 3.4 Zr 1.6 Sc 0.4 Si 2 PO 12 shows a superior Na-ion conductivity, up to 1.77×10 -3 S cm -1 at room temperature, and excellent Na metal compatibility, as confirmed by symmetrical cell test. Furthermore, the solid-state sodium battery with the configuration of Na 3 V 2 (PO 4 ) 3 /Na 3.4 Zr 1.6 Sc 0.4 Si 2 PO 12 /Na maintains a discharge capacity of 98.7 mAh g -1 at 1C after 300 cycles at room temperature. Even at 0 °C, the battery still displays a reversible capacity of 99.2 mAh g -1 at 0.1C after 100 cycles. Through the structure analysis and ex-situ and in-situ characterizations, the reasons that dominate the excellent performance of the assembled all-solid-state sodium battery with NASICON electrolytes is revealed. © 2022, The Authors. All rights reserved.

关键词： Solid electrolytes

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Robust Local PMU Measurement Recovery Based on Singular Spectrum Analysis of Hankel Structures

Robust Local PMU Measurement Recovery Based on Singular Spec...

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Sustainable Power and Energy Conference (iSPEC)

作者： Jianhua Pei Zhipeng Wu Jingyu Wang Dongyuan Shi State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781665414401

The development of cyber-physical power systems gives rise to the concerns on the data quality issue of phasor measurement units (PMUs). Low signal-to-noise ratios (SNRs) and data missing caused by malicious electromagnetic interference, false data injections, and equipment malfunctioning may jeopardize the integrity and availability of power system monitoring, protection, and control applications. To ensure grid resiliency, this paper proposes a PMU measurement recovery method based on the singular spectrum analysis of Hankel structures. It utilizes single or multiple channels of PMU time-series to restore the problematic phasor measurements with low SNRs and data losses. Numerical case studies demonstrate that the proposed method can recover the noise-contaminated measurements with higher accuracy than traditional methods such as filtering and wavelet analysis, and can effectively complete the missed data. The latency margins of power system applications can be satisfied in the mean time.

关键词： electromagnetic interference Wavelet analysis Phasor measurement units Loss measurement Real-time systems Power systems Spectral analysis

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Photoemission of Semiconductor Photocathodes for current quantization 3

Photoemission of Semiconductor Photocathodes for current qua...

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3rd IEEE China International Youth Conference on Electrical engineering, CIYCEE 2022

作者： Zhang, Haiming Li, Kehan Wang, Jian Li, Xiaofei Hu, Chen Fan, Kuanjun Huazhong University of Science and Technology China School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China State Grid Hunan Electric Power Co. Ltd Changsha410000 China China Electric Power Research Institute Wuhan430074 China State Grid Jiangxi Electric Power Co China State Grid Jiangxi Electric Power Co. Ltd Nanchang330096 China

ISBN: (数字)9781665477321

ISBN: (纸本)9781665477321

The SI system was redefined, and the ampere was defined based on the elementary charge of a single electron. Different devices have been studied to conform to the new definition for practical application. In contrast with a single-electron transistor (SET) that can count individual electrons, a photocathode electron gun-based device that measures a group of electrons is being proposed, which can provide large current several orders higher than SET. A photocathode is an electron source that plays a critical role in the device. This paper studies the photocathodes' photoemission process and quantum efficiency (QE). A revised theoretical expression of QE has been obtained, which agrees well with the simulation and experimental data. It covers the photoemission situation from minimum to saturation with different thicknesses of the buffer layer. © 2022 IEEE.

关键词： Photocathodes

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NIR-Ⅱ Excitation and NIR-I Emission Based Two-photon Fluorescence Lifetime Microscopic Imaging Using Aggregation-induced Emission Dots

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Chemical Research in Chinese Universities 2021年第1期37卷 171-176页

作者： LIU Wen ZHANG Yuhuang QI Jj QIAN Jun TANG Ben Zhong State Key Laboratory of Modern Optical Instrumentations Centre for Optical and Electromagnetic ResearchCollege of Optical Science and EngineeringInternational Research Center for Advanced PhotonicsZhejiang UniversityHangzhou310058P.R.China Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates South China University of TechnologyGuangzhou510640P.R.China Department of Chemistry The Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and ReconstructionInstitute for Advanced Study and Department of Chemical and Biological Engineering and Institute of Molecular Functional MaterialsThe Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongP.R.China

Near-infrared(NIR)lights are powerful tools to conduct deep-tissue imaging since NIR-Ⅰ wavelengths hold less photon absorption and NIR-Ⅱ wavelengths serve low photon scattering in the biological tissues compared with visible ***-photon fluorescence lifetime microscopy(2PFLM)can utilize NIR-Ⅱ excitation and NIR-Ⅰ emission at the same time with the assistance of a well-designed fluorescent *** induced emission(AIE)dyes are famous for unique optical properties and could serve a large two-photon absorption(2PA)cross-section as aggregated ***,we report two-photon fluorescence lifetime microscopic imaging with NIR-Ⅱ excitation and NIR-Ⅰ emission using a novel deep-red AIE *** AIE-gens held a 2PA cross-section as large as 1.61×10^(4)GM at 1040 *** AIE dots had a two-photon fluorescence peak at 790 nm and a stable lifetime of 2.2 ns under the excitation of 1040 nm femtosecond *** brain vessels of a living mouse were vividly reconstructed with the two-photon fluorescence lifetime information obtained by our home-made 2PFLM *** vessels as small as 3.17µm were still observed with a nice signal-background ratio at the depth of 750µ*** work will inspire more insight into the improvement of the working wavelength of fluorescent agents and traditional 2PFLM.

关键词： Near-infrared Brain imaging Aggregation-induced emission Two-photon fluorescence lifetime microscopic imaging

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Target-Oriented WiFi Sensing for Respiratory Healthcare: from Indiscriminate Perception to In-Area Sensing

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IEEE Network 2024年

作者： Wang, Meng Huang, Jinyang Zhang, Xiang Liu, Zhi Li, Meng Zhao, Peng Yan, Huan Sun, Xiao Dong, Mianxiong Hefei University of Technology Anhui Province Key Laboratory of Affective Computing and Advanced Intelligence Machine School of Computer and Information Hefei230601 China University of Science and Technology of China CAS Key Laboratory of Electromagnetic Space Information Hefei230026 China The University of Electro-Communications Department of Computer and Network Engineering Tokyo1828585 Japan Guizhou Normal University School of Big Data and Computer Science Guiyang550025 China Muroran Institute of Technology Department of Sciences and Informatics 0508585 Japan

Driven by the vision of integrated sensing and communication (ISAC) toward 6G technology, the WiFi-based respiration sensing approach has emerged as a highly competitive candidate for advanced healthcare services. Nevertheless, the indiscriminate perception of all the moving objects within the sensing area raises challenges for system stability and robustness for real-world deployment, especially for the susceptibility to motion interference from other people. Meanwhile, thanks to the emerging in-area wireless sensing technologies, i.e., beamforming, the dynamic environment tolerance of these technologies gives crucial opportunities for target-oriented WiFi-based healthcare services. This article discusses the compelling intersection of in-area WiFi sensing and the future of target-oriented intelligent respiratory healthcare network services. We first present a novel WiFi-based healthcare-assisting framework tailored for inter-user motion interference-tolerable (IMIT) sensing. The detailed components of low-level signal preprocessing, target-direction signal extraction, and healthcare-related services are discussed. By utilizing CSI beamforming technology, which adjusts a directional beam toward the desired direction and adaptively places beam nulls in noisy directions, we can mitigate motion interference and achieve target-oriented healthcare sensing. Finally, we discuss open challenges and potential solutions for target-oriented WiFi healthcare sensing. © 1986-2012 IEEE.

关键词： Wireless local area networks (WLAN)

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Mechanism Analysis of Impact of Wind Power Generation on Synchronous Generator Damping

Mechanism Analysis of Impact of Wind Power Generation on Syn...

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Sustainable Power and Energy Conference (iSPEC)

作者： Wei He Xiaojie Zhang Yunpeng Zhou State Key Laboratory of Advanced Electromagnetic Engineering and Technology and School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781665414401

This paper presents an insight view on how doubly fed induction generator (DFIG) type wind power source influences the small signal stability of power system. Firstly, DFIG wind turbine is modeled as a controllable voltage source and its internal voltage is defined. Secondly, a standard source which is considered to supply no damping effect is proposed. Thirdly, the impacts of DFIG in some common control modes on synchronous generator (SG) damping are analyzed respectively based on an extended Hefferon–Phillips model by comparing DFIG and the standard source. From the extended Hefferon– Phillips model, how the internal voltage of DFIG responds and influences the variation of rotor speed of synchronous generator is analyzed and some useful conclusions are obtained. To validate the analysis, a detailed electromagnetic transient time domain simulation is carried out.

关键词： Damping Analytical models Doubly fed induction generators Rotors Wind power generation Power system stability Synchronous generators

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Concept Design of BU for Mesh-like Constant Current Seafloor Observation Networks

Concept Design of BU for Mesh-like Constant Current Seafloor...

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Electrical engineering (CIYCEE), IEEE China International Youth Conference on

作者： Peng Fan Ying Xu Li Ren Yuejin Tang Jing Shi Jingdong Li State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781665400657

Cabled undersea observation networks have been attracting increasing research attention due to the abilities of abundant power distribution and broad bandwidth communication. Stability of their power supply systems is crucial for their normal operation. However, rare studies were carried out on constant current (CC) mesh-like undersea observation networks. This paper focuses on designing branching unit (BU) for CC mesh-like seafloor observation network. Firstly, the design concept of CC mesh-like submarine power system is introduced, as well as the equivalent model of power delivery submarine cable and the circuit of CC converters. Then, based on features of the power network, concept of BU for mesh-like CC system is proposed respectively, and reliability protection schemes for various scenarios are analyzed. The model of the observatory network was set in MATLAB, Simulations were carried out, from which results showed good consistence, verifying the theoretical methods.

关键词： Power supplies Sea floor Surge protection Reliability theory Power system stability Mathematical models Topology

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