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Charge Accumulation Characteristics of SF6-Epoxy Interface Under Negative Repetitive Nanosecond Pulses

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1808-1815页

作者： Shaocong Wu geng Chen Yuming Shao Hao Xu Xuanning Zhang Yanyu Liang Youping Tu State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources and the Beijing Key Laboratory of High Voltage and EMC North China Electric Power UniversityBeijing 102206China

Repetitve nanosecond impulses in gas-insulated metal-enclosed switchgear (GIS) are likely to trigger inside flashover. Interface charges on the spacer in GIS are considered one of the main factors damaging insulation performance and may be induced by overvoltage. For good understanding of insulation failures, accumulation characteristics of charges between SF6 and epoxy spacers under repetitive nanosecond impulses are investigated. It can be found under nanosecond impulses, the charge source in gas volume contributes to interface charge accumulation predominantly. Interface charges will be promoted by impulse number and amplitude. Accumulation processes are analyzed based on runaway electrons mechanism. When impulse amplitude exceeds a threshold value, discharge in the gas volume turns to a runaway mode. A runaway electron leads to the interface charge accumulation. Affected by motion of the runaway electrons, the potential peak gradually moves close to the grounded electrode when impulse amplitude is raised. Meanwhile, increasing impulse number can enhance surface potential. Surface potential will reach saturation eventually. However, memory effect of the repetitive impulse discharge makes the half-peak width of the surface potential at the interface change little. Design of GIS gas-solid insulations can refer to this research.

关键词： GIS interface charge repetitive nano-second pulse SF6

Intelligent overheating fault diagnosis for overhead transmission line using semantic segmentation

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High Voltage 2024年第2期9卷 309-318页

作者： Xiangyu Yang Youping Tu Zhikang Yuan Zhong Zheng geng Chen Cong Wang Yan Xu Beijing Key Laboratory of High Voltage and EMC North China Electric Power UniversityBeijingChina College of Electronic and Information Engineering Tongji UniversityShanghaiChina

The strain clamps and leading wires are important components that connect conductors on overhead transmission lines and conduct *** operation,poor contact between these components can cause abnormal overheating,leading to electric failures and threatening power system ***,the use of unmanned aerial vehicles equipped with infrared thermal imagers for strain clamp and leading wire maintenance has become increasingly *** learning-based image recognition shows promising prospects for intelligent fault diagnosis of overheating faults.A pre-treatment method is proposed based on dynamic histogram equalisation to enhance the contrast of infrared *** DeepLab v3+network,loss function,and existing networks with different backbones are *** DeepLab v3+network with ResNet101 and convolutional block attention module added,and the Focal Loss function achieved the highest performance with an average pixel accuracy of 0.614,an average intersection over union(AIoU)of 0.567,an F1 score of 0.644,and a frequency weighted intersection over union of 0.594 on the test *** optimised Atrous rates has increased the AIoU by 12.91%.Moreover,an intelligent diagnosis scheme for evaluating the defect state of the strain clamps and leading wires is proposed and which achieves a diagnostic accuracy of 91.0%.

关键词： union fault diagnosis

Recent progress in single crystal perovskite X-ray detectors

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Science China(Information Sciences) 2024年第3期67卷 5-19页

作者： Xiao LIU Jun REN Yu-Ang CHEN Xiangshun geng Dan XIE Tian-Ling REN School of Integrated Circuits Tsinghua University Beijing National Research Center for Information Science and Technology (BNRist)

Perovskites have attracted extensive attention as radiation detection material due to their long carrier diffusion length and lifetime, high absorption coefficient, and flexible manufacturing process. Compared with polycrystalline structures, single crystal perovskites improve the performance of optoelectronic devices due to their low defect state density, better photoelectric characteristics, and chemical ***, we review the recent progress of single crystal perovskite X-ray detectors. First, we briefly introduced the basic concepts, detection mechanisms, figure of merits of perovskite X-ray detectors, and the preparation methods of single crystal perovskites. Then, we summarized the significant advancements in single crystal perovskite X-ray detectors in recent times. Finally, we discussed the critical challenges and some practicable solutions for developing high-performance X-ray detectors.

关键词： single crystal perovskites carrier transport radiation detection X-ray detectors X-ray imaging

Nanostructured AlFeO_(3) thin films as a novel photoanode for photoelectrochemical water splitting

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Nano Research 2024年第3期17卷 1075-1085页

作者： Xin Sun Min Wang Qi geng Shuailin Chen Xiaojun Lv Xunlei Ding Meicheng Li State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources School of New EnergyNorth China Electric Power UniversityBeijing 102206China School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China

The earth-abundant and robust aluminum ferrite,AlFeO_(3)(AFO),is mainly studied in the context of ***,we demonstrate that AFO can be used as a stable solar absorber in photoelectrochemical cells for solar water splitting,exhibiting attractive *** is the first report on the photoelectrochemical activity of *** thin-film photoelectrodes prepared by solution-processing methods are composed of vertically oriented thin nanosheets,featuring the rhombohedral symmetry(R3c)and n-type *** as-prepared AFO photoanodes generate a photocurrent density of+0.78 mA·cm^(-2) at 1.23 V *** hydrogen electrode(RHE)with the photocurrent _(onset) potential(U_(onset))close to the flat band potential of 0.5 V *** in the presence of hole ***,the U_(onset) of AFO for solar water splitting coincides with the flat band potential as well,which is rare in n-type inorganic *** also report other properties of AFO associated with photoelectrochemical *** films exhibit a band gap energy of 2.31 eV and positive band edges with low ***,the carrier lifetimes in AFO films are up to millisecond timescales under the mediation of defect *** on the photoelectrochemical behavior and optoelectronic properties,we believe that AFO has great potential for application in photoelectrochemical cells.

关键词： AlFeO_(3) photoanode nanosheets photoelectrochemistry onset potential

An integrable generalization of the Fokas–Lenells equation:Darboux transformation, reduction and explicit soliton solutions

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Chinese Physics B 2024年第7期33卷 117-124页

作者：魏姣耿献国王鑫 School of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China School of Mathematics and Information Science Zhongyuan University of TechnologyZhengzhou 450007China

Under investigation is an integrable generalization of the Fokas–Lenells equation, which can be derived from the negative power flow of a 2 × 2 matrix spectral problem with three potentials. Based on the gauge transformation of the matrix spectral problem, one kind of Darboux transformation with multi-parameters for the three-component coupled Fokas–Lenells system is constructed. As a reduction, the N-fold Darboux transformation for the generalized Fokas–Lenells equation is obtained, from which the N-soliton solution in a compact Vandermonde-like determinant form is given. Particularly,the explicit one-and two-soliton solutions are presented and their dynamical behaviors are shown graphically.

关键词： Darboux transformation soliton solutions generalized Fokas–Lenells equation

Distinct clinical profiles and mutation landscapes of gliomas originating from the neocortex,mesocortex,and cerebellum

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Genes & Diseases 2024年第1期11卷 53-56页

作者： Ye Cheng Lei Zhang Xiaolong Wu Hiroaki Wakimoto Haoming geng Yukui Wei geng Xu Xinru Xiao Jie Bai Yaming Wang Zeliang Hu Leiming Wang Qingtang Lian Department of Neurosurgery Xuanwu HospitalCapital Medical UniversityBeijing 100053China Brain Tumor Research Center Massachusetts General HospitalDepartment of NeurosurgeryHarvard Medical SchoolBostonMA02134USA Department of Pathology Xuanwu HospitalCapital Medical UniversityBeijing 100053China

Gliomas originating from anatomically and developmentally distinct brain regions have different clinical ***,the molecular landscape underlying this difference remains *** analyzed key molecular mutations via sequencing and correlated them with clinical characteristics in 180 adult patients with gliomas originating from the neocortex,mesocortex,and *** of cerebellar origin had significantly longer survival than those of supratentorial origin,consistent with higher rates of mutation in key genes associated with supratentorial gliomas.

关键词： clinical cortex glioma

Experimental Study of Local Scour Around Four Piles Under Different Attack Angles and Gap Ratios

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China Ocean Engineering 2024年第4期38卷 612-624页

作者： LIU Ming-ming TANG Guo-qiang JIN Xin geng Shao-yang School of Architecture and Engineering Liaocheng UniversityLiaocheng 252000China Water-Sediment Regulation and Sand Effective Utilization Special Laboratory of Shandong Provincial Education Department Liaocheng UniversityLiaocheng 252000China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China College of Electronic Engineering Chengdu University of Information TechnologyChengdu 610225China College of Energy Chengdu University of TechnologyChengdu 610059China

In an effort to investigate and quantify the patterns of local scour,researchers embarked on an in-depth study using a systematic experimental *** research focused on the effects of local scour around a set of four piles,each subjected to different hydromechanical *** particular,this study aimed to determine how different attack angles—the angles at which the water flow impinges on the piles,and gap ratios—the ratios of the spacing between the piles to their diameters,influence the extent and nature of scour.A comprehensive series of 35 carefully designed experiments were orchestrated,each designed to dissect the nuances in how the gap ratio and attack angle might contribute to changes in the local scour observed at the base of pile *** these experimental trials,a wealth of local scour data were collected to support the *** data included precise topographic profiles of the sediment bed around the pile groups,as well as detailed scour time histories showing the evolution of scour at strategic feature points throughout the test *** analysis of the experimental data provided interesting *** study revealed that the interplay between the gap ratio and the attack angle had a pronounced influence on the scouring dynamics of the pile *** of the key observations was that the initial phases of scour,particularly within the first hour of water flow exposure,were characterized by a sharp increase in the scour depth occurring immediately in front of the *** this initial rapid development,the scour depth transitioned to a more gradual change *** contrast,the scour topography around the piles continuously *** suggests that sediment displacement and the associated sculpting of the seabed around pile foundations are sustained and progressive processes,altering the underwater landscape over *** results of this empirical investigation have significant implications for the design and constructio

关键词： local scour piles gap ratio attack angle

气候与构造控制下湖相优质烃源岩的差异分布——以渤中凹陷为例

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石油学报 2019年第2期40卷 165-175页

作者：姜雪刘丽芳孙和风黄胜兵耿名扬陈少平李楠沈朴中海油研究总院有限责任公司北京100028 中国海洋石油国际有限公司北京100027

基于地球化学、测井和沉积相等资料开展了渤中凹陷的优质烃源岩分析。结合区域地震解释,对渤中凹陷优质烃源岩的分布进行了刻画,并探讨了气候、构造作用下优质烃源岩分布的差异性。结果表明,受气候控制的咸化环境与受构造控制的快速沉... 详细信息

基于地球化学、测井和沉积相等资料开展了渤中凹陷的优质烃源岩分析。结合区域地震解释,对渤中凹陷优质烃源岩的分布进行了刻画,并探讨了气候、构造作用下优质烃源岩分布的差异性。结果表明,受气候控制的咸化环境与受构造控制的快速沉降环境所形成的优质烃源岩具有不同的富集特征。在咸化环境控制下,沙河街组一段优质烃源岩的分布面积占洼陷面积的81.9%,呈广覆式分布;在构造沉降控制下,平面上,沙河街组三段和东营组三段的洼陷沉降速率与优质烃源岩所占洼陷面积的比例呈明显正相关,纵向上,湖泊的氧化-还原界面控制了优质烃源岩的富集程度。在气候形成的咸化环境和构造快速沉降的控制下,渤中凹陷及邻区优质烃源岩的发育条件可分为3类:以咸化水体为主导、以构造沉降为主导以及咸化水体-构造沉降共同控制。在潮湿气候和构造沉降速率较低的情况下,不发育优质烃源岩。

关键词：优质烃源岩古气候咸化环境构造沉降渤中凹陷

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铁棍山药超声强化热泵干燥的品质特性研究

食品与发酵工业 2023年第3期49卷 234-242页

作者：薛扬刘恩宠耿鸣阳李梦孙雪董钟刘云宏河南科技大学食品与生物工程学院河南洛阳471000 食品绿色加工与质量安全控制河南省国际联合实验室河南洛阳471000 食品微生物河南省工程技术研究中心河南洛阳471000

为了探究铁棍山药超声强化热泵干燥的品质特性,对铁棍山药进行超声强化热泵干燥,研究干燥温度及超声功率对铁棍山药品质的影响,并结合权重分析确定最佳干燥条件。结果表明,干燥温度和超声功率对样品的脱水时间、微观结构、硬度值、复水... 详细信息

为了探究铁棍山药超声强化热泵干燥的品质特性,对铁棍山药进行超声强化热泵干燥,研究干燥温度及超声功率对铁棍山药品质的影响,并结合权重分析确定最佳干燥条件。结果表明,干燥温度和超声功率对样品的脱水时间、微观结构、硬度值、复水比、ΔE值、多酚含量、多糖含量及IC50值均有显著影响。在干燥温度65℃、超声功率60 W的条件下,样品的干燥时间最短(240 min)、硬度值最小(628.39 g),复水比最大(2.31 g/g),在干燥温度55℃、超声功率60 W的条件下,样品的多酚含量和多糖含量最大、ΔE值和IC50值最小,分别为36.17μg/g、137.47μg/g、47.99和33.27μg/mL。基于变异系数法的权重分析表明,在干燥温度55℃和超声功率60 W条件下所得铁棍山药样品的综合评分最高,表明上述条件即为铁棍山药超声强化热泵干燥最优参数。研究成果可为超声强化热泵干燥技术研发与应用提供参考。

关键词：铁棍山药干燥超声热泵干燥品质特性权重分析