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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 ***,current methods for measuring the hot-spot temperature of transformers do not apply to those already in operation and suffer from data *** study introduces a novel inversion method that combines ultrasonic sensing technology,multiphysics simulation,and the K-nearest neighbors *** the penetrative ability and temperature sensitivity of ultrasonic sensing,a detailed physical field simulation model was *** study extensively investigates the characteristics of ultrasonic wave signals inside *** investigation includes different temperature fields,ranging from 40℃ to 110℃ at 10℃ intervals,and various ultrasonic wave emitter *** 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 *** 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

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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

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推进天河区市政道路工程高质量建设研究

广东土木与建筑 2024年第5期31卷 49-51,94页

作者：刘杰峰广州市天河区建设工程项目代建局广州510660

通过推进市政道路工程高质量建设、提高城市交通出行品质的研究,对天河区的道路进行系统梳理、深入剖析,确定一批确需品质提升的项目,全面提升城市出行品质,同步总结过程经验,指导后续项目建设,强化始终时候管理,加强项目完工后养护,确... 详细信息

通过推进市政道路工程高质量建设、提高城市交通出行品质的研究,对天河区的道路进行系统梳理、深入剖析,确定一批确需品质提升的项目,全面提升城市出行品质,同步总结过程经验,指导后续项目建设,强化始终时候管理,加强项目完工后养护,确保良好使用品质。

关键词：高质量发展提高管理水平市政道路工程

Repeated-batch Cultivation of Encapsulated Monascus purpureus by Polyelectrolyte Complex for Natural Pigment Production

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Chinese Journal of Chemical Engineering 2010年第6期18卷 1013-1017页

作者： liu jiefeng REN Yiran YAO Shanjing Department of Chemical and Biological Engineering Zhejiang University Hangzhou 310027 China Department of Biotechnology and Food Engineering Maoming College Maoming 525000 China

In general,productions of natural pigment in submerged microorganism culture were much less than that in solid-state fermentation,because the solid-state culture can provide a support carrier for the mycelium. To improve natural pigment production,the cultivation of Monascus purpureus in submerged encapsulated cell was investigated. Monascus purpureus immobilized in polyelectrolyte complex(PEC) microcapsules,which were pre-pared by sodium cellulose sulphate(NaCS) and poly-dimethyl-diallyl-ammonium chloride(PDMDAAC),was a good substitute for submerged cell culture because it mimicked the solid-state environment. The repeated-batch process with encapsulated cells was studied in flasks and a bubble column. The results indicated that the bubble column was more suitable for the encapsulation culture than the shaking flasks because of its good mass transfer performance and minor shear stress on cells. Owing to the protection of the microcapsule's membrane,Monascus purpureus in microcapsules increased approximately three times over that in free cell culture with negligible cell leakage to the medium. The pigment production in the bubble column finally reached 3.82(OD500) ,which was two times higher than in free cell culture. In addition,the duration of each batch was shortened to 15% of that in free cell culture.

关键词： microencapsulation Monascus purpureus natural pigment polyelectrolyte complex NaCS-PDMDAAC capsule cell immobilization

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 ***,we first introduce the notion of a bidifferential graded Lie algebra and thus give Maurer-Cartan characterizations of compatible Lie *** we introduce a cohomology theory of compatible Lie algebras and use it to classify infinitesimal deformations and abelian extensions of compatible Lie *** 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 ***,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 ***,the polarization information will be obscured by its conductance effect,it is thus hard to analyse the polarization behaviour by using the traditional FDS *** 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 *** proposed feature pa-rameters are later used to analyse the polarization loss information under ageing ***,the polarization loss surface is constructed by using these feature parameters to characterise the ageing degrees of oil-immersed ***,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

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 *** 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

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 ***,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 *** this issue,this work proposes an improved second-order kinetic model accounting for the non-uniform thermal ***,oil-paper insulation samples with different ageing stages are prepared under the non-uniform thermal ***,the sample's experimental data of moisture dispersion and distribution of degree of polymerisation are *** this basis,the improved second-order kinetic model is derived to simulate insulating paper's ageing process subjected to an axial temperature ***,the relationship of the parameters in the improved second-order kinetic model with the temperature and moisture content at different winding heights is ***,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 *** 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 *** 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 ***,there are two shortcomings in the algorithms for solving the BCT *** 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 *** 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 ***,a vectorisation technology is used in the method to optimise the ***,the adaptive time‐stepping method is introduced in simulation to reduce computation time and calculation *** results are obtained by programing and later presented,which are basically consistent with the corresponding experimental ***,the proposed method is expected to promote the opti-mization design of the oil-paper insulation system.

关键词： charge insulation transport

Thermally tunable microfiber knot resonator with flexible graphene heater

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Chinese Optics Letters 2021年第5期19卷 37-42页

作者： Yunzheng Wang Qing Wu Huide Wang jiefeng liu Zheng Zheng Meng Zhang Han Zhang International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China Singapore University of Technology and Design Singapore 487372Singapore School of Electronic and Information Engineering Beihang UniversityBeijing 100191China Beijing Advanced Innovation Center for Big Data-Based Precision Medicine Beihang UniversityBeijing 100083China

Efficiently tuning the output intensity of an optical device is of vital importance for the establishment of optical interconnects and ***-optical modulation is an easily implemented and convenient approach and has been widely employed in photonic *** this paper,we proposed a novel thermo-optical modulator based on a microfiber knot resonator(MKR)and graphene *** applying voltage to graphene,the resonant property of the MKR could be thermally tuned with a maximum phase shift of 2.1π.Intensity modulation shows a fast optical response time thanks to the high thermal conductivity of graphene and the thin microfiber diameter of the MKR.

关键词： microfiber knot resonator graphene heater thermo-optical modulation