检索结果-南通市图书馆

Simulation of Ultrasonic Propagation in Transformers within Thermal Fields and Intelligent Methodology for Hot-spot Temperature Recognition

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

A method for detecting two-dimensional plane stress distribution in basin-type insulator based on critically refracted longitudinal wave

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Voltage 2024年第1期9卷 105-116页

作者： Zhaoyang Kang Fuqiang Ren Hongru Zhang Jingjing Yang Kaining Hou qingquan li Dongxin He Hongshun liu Yongzhi Zhao Huaxin Wen Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical EngineeringShandong UniversityJinanChina Shandong Electrical Engineering&Equipment Group Co.Ltd JinanChina SDEE Hitachi High-voltage Switchgear Co. LtdJinanChina

Basin-type insulator often has small cracks due to stress concentration.The current method cannot accurately reflect the stress condition of the insulator to find the stress concentration areas.To solve these problems,a method for detecting two-dimensional plane stress(δ_(1) andδ_(2))within different depth ranges in a basin-type insulator is proposed based on critically refracted longitudinal(LCR)wave.First,the acoustoelastic equation characterising the relationship between the variation of LCR wave propagation time and the plane stress was derived.Next,the propagation characteristics of LCR wave in epoxy resin samples were investigated.Then,the stress distribution within different depth ranges of the insulator subjected to hydraulic load was measured using the proposed method,including direction(θ),δ_(1) andδ_(2).The results show that the magnitude of the stress alone cannot accurately characterise the stress state.Points with equal distances to the centre have similar stress magnitudes,but their directions are not the same.With increasing depth,θremains essentially unchanged at the same location,whileδ1 andδ2 decrease,and the rate of decrease varies at different locations.Comparing the measured and simulated data,the results showed that they were in good agreement,and the maximum errors of stress value andθwere 0.69 MPa and 2.97°,respectively,which confirmed the feasibility and accuracy of the stress detection in the proposed method.

关键词： stress insulator wave

Complementary and alternative medicine on cognitive defects and neuroinflammation after sepsis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Traditional Chinese Medicine 2024年第2期44卷 408-416页

作者： li Zhenxuan WANG Xuerui Luis Ulloa Ayman Youssef BAI Yunjing XU Xiaolong liU qingquan Department of Infectious Diseases Beijing Hospital of Traditional Chinese MedicineCapital Medical UniversityBeijing 100010China Beijing Key Laboratory of Basic Research with Traditional Chinese Medicine on Infectious Diseases Beijing 100010China Infection immunity laboratory Beijing Institute of Traditional Chinese MedicineBeijing 100010China Clinical College of Traditional Chinese Medicine Capital Medical UniversityBeijing 100069China Center for Perioperative Organ Protection Department of AnesthesiologyDuke University Medical CenterDurhamNorth Carolina 27710USA

Sepsis-associated encephalopathy(SAE)is a common manifestation of sepsis,ranging from mild confusion and delirium to severe cognitive impairment and deep coma.SAE is associated with higher mortality and long-term outcomes,particularly substantial declines in cognitive function.The mechanisms of SAE probably include neuroinflammation that is mediated by systemic inflammation and ischemic lesions in the brain,a disrupted blood–brain barrier,oxidative stress,neurotransmitter dysfunction,and severe microglial activation.Increasing evidence suggests that complementary and alternative medicine,especially Traditional Chinese Medicine(TCM),is favorable in alleviating cognitive decline after sepsis.Here,we summarized the studies of traditional herbal remedies,TCM formulas and acupuncture therapy in animal models of neurological dysfunctions after sepsis in recent decades and reviewed their potential mechanisms.

关键词： sepsis-associated encephalopathy cognitive dysfunction complementary therapies neuroinflammatory diseases medicine Chinese traditional review

Study on partial discharge and charge accumulation characteristics of oil‐pressboard insulation under DC superimposed harmonic voltage

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

High Voltage 2023年第6期8卷 1215-1224页

作者： Shuqi li Qiang Wang Dongxin He liangkai Wang qingquan li Wen Si Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical EngineeringShandong UniversityJinanChina Zibo City Product Quality Inspection Institute ZiboChina School of Information and Electrical Engineering Shandong Jianzhu UniversityJinanChina

The oil‐pressboard insulation on the valve side of the converter transformer withstands pulsating square wave voltage.The voltage contains lots of DC components and high‐order harmonics,which is likely to cause insulation failures.The partial discharge and space charge experiments of oil‐impregnated pressboard under DC superimposed har-monic voltage are conducted to study the effects of harmonic frequency and DC com-ponents on the discharge and charge accumulation and to explore the correlation mechanism of charge dynamic behaviour and discharge.Firstly,it is found that high‐order harmonic voltage promotes the partial discharge generation,but DC component sup-presses the discharge.Moreover,the charge inside the pressboard is mainly injected in the same polarity and accumulates over time.The space charge density near the electrode increases with the increase of harmonic frequency,and the large amount of charge in-jection leads to electric field distortion.Meanwhile,the electric field direction changes faster,and the frequent charge injection and extraction behaviours make the charge recombination intensify,which promotes the discharge.Through the above analysis,the influence law of harmonic voltage on the failure of oil‐pressboard insulation is obtained,providing a theoretical basis for the structural optimisation and condition assessment of the converter transformer insulation.

关键词： harmonic insulation charge

enOsCas12f1-mediated exon skipping for Duchenne muscular dystrophy therapy in humanized mouse model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Genetics and Genomics 2024年第2期51卷 256-259页

作者： Ming Jin Jiajia lin Yu Zhang qingquan Xiao Xiangfeng Kong Xiumei Zhang Zhurui Shao Yin Wang Yuyang Yu Jinjing li Wan-Jin Chen Guoling li Hui Yang Ning Wang Department of Neurology and Institute of Neurology of First Affiliated Hospital Institute of NeuroscienceFujian Key Laboratory of Molecular NeurologyFujian Medical UniversityFuzhouFujian 350004China HUIDAGENE Therapeutics Co. Ltd.Shanghai 200131China Institute of Neuroscience State Key Laboratory of NeuroscienceKey Laboratory of Primate NeurobiologyCAS Center for Excellence in Brain Science and Intelligence TechnologyShanghai Institutes for Biological SciencesChinese Academy of SciencesShanghai 200031China

Duchenne muscular dystrophy(DMD)is a severe neuromuscular disorder caused by mutations in the dystrophin gene,which encodes the essential protein dystrophin.This genetic condition,affecting approximately 1 in 5000 male births worldwide(Birnkrant et al.,2018),is characterized by progressive muscle weakness and wasting,leading to premature death in the second or third decade of life(Farini et al.,2016).The absence of dystrophin protein causes instability in the sarcolemma,which predisposes individuals to myonecrosis and activation of inflammatory signaling cascades.Unfortunately,there is currently no effective cure for DMD,and glucocorticoid steroids are commonly used in clinical settings to delay symptom development(Merlini et al.,2003).

关键词： dystrophy Duchenne

Sub-seasonal Prediction of the South China Sea Summer Monsoon Onset in the NCEP Climate Forecast System Version 2

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2022年第11期39卷 1969-1981页

作者： Weiwei WANG Song YANG Tuantuan ZHANG qingquan li Wei WEI School of Atmospheric Sciences and Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen UniversityZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China National Climate Center China Meteorological AdministrationBeijing 100081China

This study depicts the sub-seasonal prediction of the South China Sea summer monsoon onset(SCSSMO)and investigates the associated oceanic and atmospheric processes,utilizing the hindcasts of the National Centers for Environmental Prediction(NCEP)Climate Forecast System version 2(CFSv2).Typically,the SCSSMO is accompanied by an eastward retreat of the western North Pacific subtropical high(WNPSH),development of the cross-equatorial flow,and an increase in the east-west sea surface temperature(SST)gradient.These features are favorable for the onset of westerlies and strengthening of convection and precipitation over the South China Sea(SCS).A more vigorous SCSSMO process shows a higher predictability,and vice versa.The NCEP CFSv2 can successfully predict the onset date and evolution of the monsoon about 4 pentads(20 days)in advance(within 1–2 pentads)for more forceful(less vigorous)SCSSMO processes.On the other hand,the climatological SCSSMO that occurs around the 27th pentad can be accurately predicted in one pentad,and the predicted SCSSMO occurs 1–2 pentads earlier than the observed with a weaker intensity at longer leadtimes.Warm SST biases appear over the western equatorial Pacific preceding the SCSSMO.These biases induce a weaker-thanobserved WNPSH as a Gill-type response,leading to weakened low-level easterlies over the SCS and hence an earlier and less vigorous SCSSMO.In addition,after the SCSSMO,remarkable warm biases over the eastern Indian Ocean and the SCS and cold biases over the WNP induce weaker-than-observed westerlies over the SCS,thus also contributing to the less vigorous SCSSMO.

关键词： South China Sea summer monsoon onset sub-seasonal prediction the NCEP CFSv2

Improved information entropy weighted vague support vector machine method for transformer fault diagnosis

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

High Voltage 2022年第3期7卷 510-522页

作者： Hongru Zhang Jiaxiang Sun Kaining Hou qingquan li Hongshun liu Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical EngineeringShandong UniversityJinanChina

A combined model based on improved information entropy and vague support vector machine(IVSVM)is introduced into transformer fault diagnosis using dissolved gas analysis in oil(DGA).The improved information entropy method is used to obtain the weights of each gas and to weight the raw data,and the processed training data and the corresponding fault types are inputted into the vague support vector machine(VSVM)model to obtain classifiers.Firstly,the training data are weighted by the improved information entropy method to discretise the original data from the mixed state for subsequent classifier training.Then,the vague set divides the events into true,false and unknown factors,which can optimise the sub-interface of SVM and improve the accuracy of the boundary point clas-sification.Finally,fault data from the literature and actual collections are selected for training and testing.By comparing with the widely used ratio method and artificial intelligence method,it can be concluded that the method described herein can effectively improve the accuracy of fault diagnosis.The result shows that this method has better applicability when facing actual fault type classification with higher data similarity.

关键词： fault entropy artificial

Long-term trend of water vapor over the Tibetan Plateau in boreal summer under global warming

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2022年第4期65卷 662-674页

作者： Jingwen YU qingquan li Yihui DING Jie ZHANG Qingyuan WU Xinyong SHEN Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory on Climate and Environment ChangeNanjing University of Information Science&TechnologyNanjing 210044China Laboratory for Climate Studies National Climate CenterChina Meteorological AdministrationBeijing 100081China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China

In this study,the long-term trend of water vapor over the Tibetan Plateau(TP)in boreal summer is investigated by using observation and reanalysis data from 1979 to 2019.The historical experiment simulations of 19 models that participated in the Coupled Model Intercomparison Project phase 6(CMIP6)are evaluated,and the future variation tendency under four emission scenarios is projected.The results indicate that the water vapor content and the net water vapor budget over the TP show notable increasing trends,which are mainly manifested by a significant increase in the net water vapor import and a significant decrease in the water vapor export on the eastern boundary of the TP.This is mainly due to an anomalous anticyclone from Lake Baikal to the Mongolian Plateau.The CMIP6 multi-model ensemble can well simulate the variation characteristics of the TP net water vapor budget.The projection results indicate that by the end of the twenty-first century,the water vapor content,the net water vapor import and precipitation over the TP will increase.Under a high-emissions scenario and compared with the current period(1991–2014),these three variables will increase by 47.99%,59.77%and 18.59%in the long term(2081–2100),respectively.The significant enhancement of meridional water vapor transport over the northern TP may be the main reason for the increase in humidity over the TP.

关键词： Tibetan Plateau Boreal summer Water vapor transport Long-term trend Projection

Exploring metro vibrancy and its relationship with built environment:a cross-city comparison using multi-source urban data

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Geo-Spatial Information Science 2022年第2期25卷 182-196页

作者： Wei Tu Tingting Zhu Chen Zhong Xiaohu Zhang Yang Xu qingquan li Guangdong Key Laboratory of Urban Informatics and Shenzhen Key Laboratory of Spatial Smart Sensing and ServiceSchool of Architecture and Urban PlanningShenzhen UniversityShenzhenChina Ministry of Natural Resources(MNR)Key Laboratory for Geo-Environmental Monitoring of Great Bay Area Shenzhen UniversityShenzhenChina The Bartlett Centre for Advanced Spatial Analysis(CASA) University College London(UCL)LondonUK Department of Urban Planning and Design The University of Hong KongHong KongChina Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong Kong SARChina

Recent urban transformations have led to critical reflections on the blighted urban infrastruc-tures and called for re-stimulating vital urban places.Especially,the metro has been recognized as the backbone infrastructure for urban mobility and the associated economy agglomeration.To date,limited research has been devoted to investigating the relationship between metro vitality and built environment in mega-cities empirically.This paper presents a multisource urban data-driven approach to quantify the metro vibrancy and its association with the underlying built environment.Massive smart card data is processed to extract metro ridership,which denotes the vibrancy around the metro station in physical space.Social media check-ins are crawled to measure the vitality of metros in virtual spaces.Both physical and virtual vibrancy are integrated into a holistic metro vibrancy metric using an entropy-based weighting method.Certain built environment characteristics,including land use,transportation and buildings are modeled as independent variables.The significant influences of built environ-mental factors on the metro vibrancy are unraveled using the ordinary least square regression and the spatial lag model.With experiments conducted in Shenzhen,Singapore and London,this study comes up with a conclusion that spatial distributions of metro vibrancy metrics in three cities are spatially autocorrelated.The regression analysis suggests that in all the three cities,more affluent urban areas tend to have higher metro virbrancy,while the road density,land use and buildings tend to impact metro vibrancy in only one or two cities.These results demonstrate the relationship between the metro vibrancy and built environment is affected by complex urban contexts.These findings help us to understand metro vibrancy thus make proper policy to re-stimulate the important metro infrastructure in the future.

关键词： Urban vibrancy spatial-autocorrelation spatial lag model smart card data social media