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Chinese Journal of Electrical Engineering 2024年第1期10卷 35-47页

作者： Dongxin He Dechao Yang Xinhua Guo jiefeng liu Haoxin Guo Qingquan Li Gilbert Teyssedre School of Electrical Engineering Shandong UniversityJinan 250061China School of Mechanical and Electronic Engineering Wuhan University of TechnologyWuhan 430070China School of Electrical Engineering Guangxi UniversityGuangxi 530004China UPS INPTCNRSLAPLACE(Laboratoire Plasma et Conversion d’Energie)University of ToulouseToulouse 31100France

Hot-spot temperature of transformer windings is a crucial indicator of internal defects.However,current methods for measuring the hot-spot temperature of transformers do not apply to those already in operation and suffer from data lag.This study introduces a novel inversion method that combines ultrasonic sensing technology,multiphysics simulation,and the K-nearest neighbors algorithm.Leveraging the penetrative ability and temperature sensitivity of ultrasonic sensing,a detailed physical field simulation model was established.This study extensively investigates the characteristics of ultrasonic wave signals inside transformers.The investigation includes different temperature fields,ranging from 40℃ to 110℃ at 10℃ intervals,and various ultrasonic wave emitter conditions.By extracting the key features of the acoustic signals,such as the peak time,propagation time,and peak amplitude,an accurate inversion of the winding hot-spot temperature is successfully achieved.The results demonstrate that this method achieves a high accuracy rate(98.57%)in inverting the internal winding hot-spot temperatures of transformers,offering an efficient and reliable new approach for measuring winding hot-spot temperatures.

关键词： Ultrasonic temperature measurement non-destructive testing oil-immersed transformers machine learning

Perfluorinated iodine alkanes promote the differentiation of mouse embryonic stem cells by regulating estrogen receptor signaling

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Journal of Environmental Sciences 2024年第3期137卷 443-454页

作者： Zhihua Ren Xiaoxi Yang Tingting Ku Qian S.liu jiefeng Liang Qunfang Zhou Francesco Faiola Guibin Jiang State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China College of Environment and Resource Research Center of Environment and HealthShanxi UniversityTaiyuan 030006China College of Sino-Danish University of Chinese Academy of SciencesBeijing 100049China

Investigating the development toxicity of perfuorinated iodine alkanes(PFIs)is critical,given their estrogenic effects through binding with estrogen receptors(ERs).In the present study,two PFIs,including dodecafuoro-1,6-diiodohexane(PFHx DI)and tridecafuorohexyl iodide(PFHx I),with binding preference to ERαand ERβ,respectively,were selected to evaluate their effects on proliferation and differentiation of the mouse embryonic stem cells(m ESCs).The results revealed that,similar to E_(2),50μmol/L PFHx DI accelerated the cell proliferation of the m ESCs.The PFI stimulation at the exposure concentrations of 2–50μmol/L promoted the differentiation of the m ESCs as characterized by the upregulation of differentiation-related biomarkers(i.e.,Otx2 and Dnmt3β)and downregulation of pluripotency genes(i.e.,Oct4,Nanog,Sox2,Prdm14 and Rex1).Comparatively,PFHx DI exhibited higher induction effect on the differentiation of the m ESCs than did PFHx I.The tests on ER signaling indicated that both PFI compounds induced exposure concentration-dependent expressions of ER signaling-related biomarkers(i.e.,ERα,ERβand Caveolin-1)in the m ESCs,and the downstream ER responsive genes(i.e.,c-fos,c-myc and c-jun)well responded to PFHx I stimulation.The role of ER in PFI-induced effects on the m ESCs was further validated by the antagonistic experiments using an ER inhibitor(ICI).The findings demonstrated that PFIs triggered ER signaling,and perturbed the differentiation program of the m ESCs,causing the potential health risk during early stage of development.

关键词： Perfuorinated iodine alkanes(PFIs) Embryonic stem cells(ESCs) Developmental toxicity Cell differentiation Estrogen receptor-related signaling

Maurer-Cartan characterizations and cohomologies of compatible Lie algebras

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Science China Mathematics 2023年第6期66卷 1177-1198页

作者： jiefeng liu Yunhe Sheng Chengming Bai School of Mathematics and Statistics Northeast Normal UniversityChangchun 130024China Department of Mathematics Jilin UniversityChangchun 130012China Chern Institute of Mathematics&LPMC Nankai UniversityTianjin 300071China

In this paper,we give Maurer-Cartan characterizations as well as a cohomology theory for compatible Lie algebras.Explicitly,we first introduce the notion of a bidifferential graded Lie algebra and thus give Maurer-Cartan characterizations of compatible Lie algebras.Then we introduce a cohomology theory of compatible Lie algebras and use it to classify infinitesimal deformations and abelian extensions of compatible Lie algebras.In particular,we introduce the reduced cohomology of a compatible Lie algebra and establish the relation between the reduced cohomology of a compatible Lie algebra and the cohomology of the corresponding compatible linear Poisson structures introduced by Dubrovin and Zhang(2001)in their study of bi-Hamiltonian structures.Finally,we use the Maurer-Cartan approach to classify nonabelian extensions of compatible Lie algebras.

关键词： compatible Lie algebra Maurer-Cartan element cohomology deformation extension

Polarization loss analysis and ageing characterisation of transformer oil-immersed insulation by using decoupled frequency domain spectroscopy

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High Voltage 2022年第3期7卷 575-585页

作者： Xianhao Fan jiefeng liu Yiyi Zhang Zheshi Ding Qingyin Wang Guangxi Key Laboratory of Intelligent Control and Maintenance of Power Equipment Guangxi UniversityNanningGuangxiChina

The polarization information contained in the frequency-domain spectroscopy(FDS)could be utilised for characterising the ageing degree of transformer oil-immersed insulation.However,the polarization information will be obscured by its conductance effect,it is thus hard to analyse the polarization behaviour by using the traditional FDS technique.Given this issue,an alternative approach is proposed to analyse the polari-zation information using FDS decoupled by logarithmic-derivative spectroscopy(LDS).Findings proved that the polarization loss information generated by polarization behaviour can be separated from the total dispersion loss.The proposed feature pa-rameters are later used to analyse the polarization loss information under ageing impact.Also,the polarization loss surface is constructed by using these feature parameters to characterise the ageing degrees of oil-immersed samples.Finally,the potential possibility of using the proposed method to analyse the polarization loss and ageing degree are respectively discussed.

关键词： immersed polarization character

An improved second-order kinetic model for degradation analysis of transformer paper insulation under non-uniform thermal field

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High Voltage 2023年第1期8卷 81-90页

作者： jiefeng liu Kuo Jiang Qingyin Wang Heng Zhang Enze Zhang Xianhao Fan Yiyi Zhang School of Electrical Engineering Guangxi UniversityGuangxiNanningChina

The ageing kinetic model is regarded as an effective tool to describe the degradation of transformer paper insulation.However,the temperature of the transformer winding is unevenly distributed,and the existing ageing kinetic models only depend on experimental data of accelerated thermal ageing at a constant temperature.Given this issue,this work proposes an improved second-order kinetic model accounting for the non-uniform thermal field.First,oil-paper insulation samples with different ageing stages are prepared under the non-uniform thermal field.Then,the sample's experimental data of moisture dispersion and distribution of degree of polymerisation are collected.On this basis,the improved second-order kinetic model is derived to simulate insulating paper's ageing process subjected to an axial temperature gradient.Further,the relationship of the parameters in the improved second-order kinetic model with the temperature and moisture content at different winding heights is obtained.Finally,the proposed model is validated,and the results show that the proposed model is more scientific than the traditional models to describe the degradation of paper insulation.In that respect,this work illustrates an improved second-order kinetic model to provide a reference for the ageing assessment/life prediction of transformer paper insulation under the non-uniform thermal field.

关键词： kinetic thermal insulation

Description of space charge transport in oil‐paper insulation using adaptive time‐stepping transient upstream finite element method

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High Voltage 2022年第1期7卷 75-85页

作者： jiefeng liu Mingchen Shi Yiyi Zhang Bing Gao Wei Zhang Shuo Liang School of Electrical Engineering Guangxi UniversityNanningChina College of Electrical and information Hunan UniversityChangshaChina Electric Power Research Institute of Guangxi Power Grid Co LtdNanningChina

The charge transport and accumulation in oil-paper can cause the insulation degradation.So far,the most widely used model to simulate space charge transport and accumulation is the bipolar charge transport(BCT)model,which can well simulate the space charge dynamics.However,there are two shortcomings in the algorithms for solving the BCT model.One is that there is almost no use of vectorisation technology,which may increase the complexity of the algorithm,the other is the usage of fixed step size which might bring extra computation cost.In view of this,an adaptive time‐stepping transient up-stream finite element method(FEM)is developed to solve the BCT model considering trapping/detrapping,as well as the recombination phenomenon under DC condition in this article.Then,a vectorisation technology is used in the method to optimise the al-gorithm.Moreover,the adaptive time‐stepping method is introduced in simulation to reduce computation time and calculation amount.Simulation results are obtained by programing and later presented,which are basically consistent with the corresponding experimental results.Therefore,the proposed method is expected to promote the opti-mization design of the oil-paper insulation system.

关键词： charge insulation transport

Analysis of low‐frequency polarisation behaviour for oil‐paper insulation using logarithmic‐derivative spectroscopy

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High Voltage 2021年第3期6卷 460-469页

作者： jiefeng liu Xianhao Fan Yiyi Zhang Benhui Lai Jian Jiao School of Electrical Engineering Guangxi UniversityNanningGuangxiChina Electric Power Research Institute Guangxi Power Grid CorporationNanningGuangxiChina

The low‐frequency polarisation information of oil‐paper insulation could be easily obscured by the conductance effect,and the contained polarisation information thus can not be readily extracted from the frequency domain spectroscopy(FDS).Given this issue,an alternative idea is reported to extract the low‐frequency polarisation infor-mation by using logarithmic‐derivative spectroscopy(LDS).The present findings proved that the parameters extracted by using the LDS can be applied for studying the low‐frequency polarisation behaviour under the moisture effect.In that respect,the novelty of this work is in the exploration of the LDS as a potential tool to extract feature parameters for analyzing the low‐frequency polarisation information of trans-former oil‐paper insulation.

关键词： effect insulation behaviour

实践者视角中的民族教育高质量发展:价值逻辑与本质取向

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教育学术月刊 2024年第5期 47-56,112页

作者：刘远杰吴杰凤游春艳广西师范大学教育学部广西桂林541006 广西民族教育发展研究中心广西桂林541006

加快推进民族教育高质量发展是新时代民族工作和教育强国建设的重要内容。本研究针对“什么是民族教育高质量发展”这一本质问题,对30名广西乡村教师进行访谈研究,旨在了解一线教师对于民族教育高质量发展的认识和理解,推进民族教育高... 详细信息

加快推进民族教育高质量发展是新时代民族工作和教育强国建设的重要内容。本研究针对“什么是民族教育高质量发展”这一本质问题,对30名广西乡村教师进行访谈研究,旨在了解一线教师对于民族教育高质量发展的认识和理解,推进民族教育高质量发展的内涵建设。研究发现:更充分、更优质、更均衡的教育资源配置,更科学、更民族、更本土的课程教学变革,更人文、更多元、更专业的教育评价革新,构成了一线教师眼中民族教育高质量发展的显著标志;以铸牢中华民族共同体意识为价值引领、以传承创新各族优秀传统文化为价值禀赋、以实现人的自由全面发展为价值旨归,构成一线教师眼中民族教育高质量发展的基本价值逻辑。本研究认为,民族教育高质量发展是以人的现代化为核心诉求,以打造具有中国特色、民族特性、时代特征和未来导向的中国现代民族教育为发展目标,以特色明、质量优及满足需求能力强为主要特征,通过不断优化和协调影响民族教育系统内外部要素和机制的方式提升民族教育整体质量的过程。

关键词：民族教育高质量发展民族教育乡村教师实践者视角

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火龙果皮花青素生物转化菌株筛选及工艺优化

中国酿造 2024年第1期43卷 197-202页

作者：程水明李露欣刘杰凤广东石油化工学院生物工程系广东茂名525000

该研究以火龙果皮粉为发酵基质,采用20种食用真菌进行发酵,通过监测发酵后发酵液中花青素含量的变化,筛选出转化效率高的供试菌株作为火龙果皮发酵菌株,并采用响应面法优化其发酵工艺。结果表明,20种食用真菌中,经蜜环菌(Armillaria mel... 详细信息

该研究以火龙果皮粉为发酵基质,采用20种食用真菌进行发酵,通过监测发酵后发酵液中花青素含量的变化,筛选出转化效率高的供试菌株作为火龙果皮发酵菌株,并采用响应面法优化其发酵工艺。结果表明,20种食用真菌中,经蜜环菌(Armillaria mellea)发酵的火龙果皮液中花青素含量最高,其最优发酵工艺为发酵时间5 d、接种量6%、发酵温度25℃、料液比1∶50(g∶mL)。在此优化条件下,发酵液中花青素含量达(2.03±0.02)mg/100 mL,是未经食用真菌转化的11.94倍,表明微生物辅助可有效转化火龙果果皮中花青素。

关键词：火龙果果皮花青素生物转化食用真菌筛选工艺优化

ExoSeal血管封堵器在急性缺血性脑卒中桥接治疗中的安全性和有效性

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介入放射学杂志 2024年第2期33卷 122-125页

作者：刘涛张纪存张杰峰刘继红潍坊市人民医院血管外科山东潍坊261000 潍坊市人民医院康复科山东潍坊261000

目的探讨ExoSeal血管封堵器在接受桥接治疗的急性缺血性脑卒中(AIS)患者中的安全性和有效性。方法回顾性分析2018年6月至2020年12月在潍坊市人民医院接受全量重组组织型纤溶酶原激活剂(rt-PA)溶栓后桥接血管腔内机械取栓治疗的142例AI... 详细信息

目的探讨ExoSeal血管封堵器在接受桥接治疗的急性缺血性脑卒中(AIS)患者中的安全性和有效性。方法回顾性分析2018年6月至2020年12月在潍坊市人民医院接受全量重组组织型纤溶酶原激活剂(rt-PA)溶栓后桥接血管腔内机械取栓治疗的142例AIS患者临床资料。所有患者在血管腔内机械取栓手术时均使用8 F股动脉鞘,术毕股动脉穿刺点由指压法封堵68例,7 F ExoSeal封堵器封堵74例。比较指压法组和封堵器组股动脉穿刺点封堵成功率及穿刺点相关并发症发生率。结果封堵器组与指压法组相比,手术成功率显著增高(94.6%比83.8%,P=0.037)。指压法组、封堵器组患者术后至出院前分别有11例(16.2%)、4例(5.4%)发生穿刺点相关并发症(P=0.030),6例(8.8%)、2例(2.7%)发生深静脉血栓(P=0.109),均未发生动静脉瘘、假性动脉瘤、同侧下肢急性缺血、穿刺点相关大出血及需要血管外科手术或介入治疗的并发症。结论 ExoSeal封堵器可安全地应用于溶栓后桥接血管腔内机械取栓治疗的AIS患者,股动脉穿刺点封堵成功率较高,且降低穿刺点血肿发生率。

关键词：血管闭合装置缺血性脑卒中桥接治疗并发症