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Effect of matrix resin components on properties of the semi-conductive shielding material for high-voltage cable

High Voltage 2024年第2期9卷 419-428页

作者： Guochang Li Tianyao Liu Xiaolong Chen yanhui wei Chuncheng Hao Shengtao Li Institute of Advanced Electrical Materials Qingdao University of Science and TechnologyQingdaoChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

The semi-conductive shielding layer is an important part of the high-voltage cable,playing a role in uniform electric field and reducing the air gap at the interface.The overall performance of the cable is affected by the semi-conductive shielding layer with different base resin composition.The matrix resins of ethylene-vinyl acetate(EVA),ethylene-ethyl acrylate(EEA)and ethylene-butyl acrylate(EBA)were used to prepare the semi-conductive shielding materials of CB/EVA,CB/EEA and CB/EBA.The influences of different matrix resins on the chemical,electrical,thermal and mechanical properties of the shielding materials were investigated.The results show that CB has the best dispersion in EBA resin and the worst dispersion in EEA resin.The temperature in-flection points of CB/EVA,CB/EEA and CB/EBA shielding materials are 90°C,100°C and 110°C,respectively,and the CB/EBA shielding material has the lowest resistivity and the weakest positive temperature coefficient effect at room temperature.The thermal conductivity of all three matrix resins is smaller than that of the shielding material,the thermal conductivity of CB/EVA and CB/EBA shielding materials show a slow increase with temperature,and the CB/EEA shielding material is the least affected by the tem-perature.The mechanical properties of the three matrix resins and the three shielding materials are EBA>EVA>EEA,among them the stress of CB/EBA shielding material is 31.0 MPa and the strain is 570%.This work has important reference significance for the selection of shielding layer matrix resin and material formulation in engineering applications.

关键词： temperature. resin resins

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Evaluation of rainfall threshold models for debris flow initiation in the Jiangjia Gully,Yunnan Province,China

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Journal of Mountain Science 2024年第6期21卷 1799-1813页

作者： YANG Hongjuan ZHANG Shaojie HU Kaiheng wei Fangqiang LIU yanhui State Key Laboratory of Mountain Hazards and Engineering Resilience Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China Chongqing School University of Chinese Academy of SciencesChongqing 400714China China Institute of Geo-Environment Monitoring Beijing 100081China

Systematically determining the discriminatory power of various rainfall properties and their combinations in identifying debris flow occurrence is crucial for early warning systems.In this study,we evaluated the discriminatory power of different univariate and multivariate rainfall threshold models in identifying triggering conditions of debris flow in the Jiangjia Gully,Yunnan Province,China.The univariate models used single rainfall properties as indicators,including total rainfall(R_(tot)),rainfall duration(D),mean intensity(I_(mean)),absolute energy(Eabs),storm kinetic energy(E_(s)),antecedent rainfall(R_(a)),and maximum rainfall intensity over various durations(I_(max_dur)).The evaluation reveals that the I_(max_dur)and Eabs models have the best performance,followed by the E_(s),R_(tot),and I_(mean)models,while the D and R_(a)models have poor performances.Specifically,the I_(max_dur)model has the highest performance metrics at a 40-min duration.We used logistic regression to combine at least two rainfall properties to establish multivariate threshold models.The results show that adding D or R_(a)to the models dominated by Eabs,E_(s),R_(tot),or I_(mean)generally improve their performances,specifically when D is combined with I_(mean)or when R_(a)is combined with Eabs or E_(s).Including R_(a)in the I_(max_dur)model,it performs better than the univariate I_(max_dur)model.A power-law relationship between I_(max_dur)and R_(a)or between Eabs and R_(a)has better performance than the traditional I_(mean)–D model,while the performance of the E_(s)–R_(a)model is moderate.Our evaluation reemphasizes the important role of the maximum intensity over short durations in debris flow occurrence.It also highlights the importance of systematically investigating the role of R_(a)in establishing rainfall thresholds for triggering debris flow.Given the regional variations in rainfall patterns worldwide,it is necessary to evaluate the findings of this study across diverse watersheds.

关键词： Rainfall threshold Logistic regression Maximum rainfall intensity Absolute energy Antecedent rainfall

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More tree growth reduction due to consecutive drought and its legacy effect for a semiarid larch plantation in Northwest China

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Journal of Forestry Research 2024年第2期35卷 188-196页

作者： Yanfang Wan Pengtao Yu yanhui Wang Jiamei Li Yushi Bai Yipeng Yu Bingbing Liu Xiaocha wei Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration Ecology and Nature Conservation InstituteChinese Academy of ForestryBeijing 100091People’s Republic of China

Extreme climate has increasingly led to negative impacts on forest ecosystems globally,especially in semiarid areas where forest ecosystems are more vulnerable.However,it is poorly understood how tree growth is affected by different drought events.In 2006–2009,the larch plantations in the semiarid areas of Northwest China were negatively affected by four consecutive dry years,which was a very rare phenomenon that may occur frequently under future climate warming.In this study,we analyzed the effect of these consecutive dry years on tree growth based on the data of the tree rings in the dominant layer of the forest canopy on a larch plantation.We found that the tree-ring width index(RWI)in dry years was lower than that in normal years,and it experienced a rapidly decreasing trend from 2006 to 2009(slope=-0.139 year^(-1),r=-0.94)due to water supply deficits in those dry years.Drought induced legacy effects of tree growth reduction,and consecutive dry years corresponded with greater growth reductions and legacy effects.Growth reductions and legacy effects were significantly stronger in the third and fourth consecutive dry years than that of single dry year(p<0.05),which might have been due to the cumulative stress caused by consecutive dry years.Our results showed that larch trees experienced greater tree growth reduction due to consecutive dry years and their legacy effect,and the trees had lower recovery rates after consecutive dry years.Our results highlight that consecutive dry years pose a new threat to plantations under climate warming,and thus,the effect of climate extremes on tree growth should be considered in growth models in semiarid areas.

关键词： Tree rings Drought effects Legacy effects Growth-climate relationships Larix principis-rupprechtii

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Spatial-Temporal Analysis of Drinking Water Type of Endemic Fluorosis—China,2009–2022

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China CDC weekly 2024年第2期6卷 25-29页

作者： Lijun Zhao Zhe Li Mang Li Hongna Sun wei wei Lin Gao Qiaoshi Zhao Yang Liu Xiaohong Ji Cheng Li Jian Wang yanhui Gao Junrui Pei Center for Endemic Disease Control Chinese Center for Disease Control and PreventionHarbin Medical UniversityHarbin CityHeilongjiang ProvinceChina Key Lab of Etiology and Epidemiology Education Bureau of Heilongjiang Province(23618504)Ministry of Health of PRHarbin Medical UniversityHarbin CityHeilongjiang ProvinceChina

What is already known about this topic?Endemic fluorosis,caused by high fluoride levels in drinking water,has been a significant health issue in rural areas of China for many decades.What is added by this report?There has been a notable decline in the detection rate of dental fluorosis in children aged 8–12 years in drinking water fluorosis areas across the country from 2009 to 2022.While 14 provincial-level administrative divisions are classified as low-probability clusters,Tianjin remains classified as a high-probability cluster.What are the implications for public health practice?The current policy for preventing and controlling endemic fluorosis in China needs adjustment.Rather than focusing solely on regions with high incidence,there should be a shift towards monitoring and early warning of fluoride exposure.Additionally,local containment measures should be intensified.

关键词： intensified Spatial fluoride

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Direct observation of oxygen vacancy formation and migration over ceria surface by in situ environmental transmission electron microscopy

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Journal of Rare Earths 2024年第4期42卷 676-682页

作者： Dawei Pang wei Li Ningqiang Zhang Hong He Shengcheng Mao yanhui Chen Liwei Cao Chong Li Ang Li Xiaodong Han Beijing Key Laboratory of Solid Microstructure and Properties Department of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Beijing Key Laboratory for Green Catalysis and Separation The Faculty of Environment and LifeBeijing University of TechnologyBeijing10124China International Joint Research Laboratory for Quantum Functional Materials of Henan School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou450001China

The extremely high structural tolerance of ceria to oxygen vacancies(Ov)has made it a desirable catalytic material for the hydrocarbon oxidation to chemicals and pharmaceuticals and the reduction of gaseous pollutants.It is proposed that the formation and diffusion of Ov originate from its outstanding reduction property.However,the formation and diffusion process of Ov over the surface of ceria at the atomic level is still unknown.Herein,the structural and valence evolution of CeO_(2)(111)surfaces in reductive,oxidative and vacuum environments from room temperature up to 700℃was studied with in situ aberration-corrected environmental transmission electron microscopy(ETEM)experiments.Ov is found to form under a high vacuum at elevated temperatures;however,the surface can recover to the initial state through the adsorption of oxygen atoms in an oxygen-contained environment.Furthermore,in hydrogen environment,the step-CeO_(2)(111)surface is not stable at elevated temperatures;thus,the steps tend to be eliminated with increasing temperature.Combined with first-principles density function calculations(DFT),it is proposed that O-terminated surfaces would develop in a hypoxic environment due to the dynamic diffusion of Ov from the outer surface to the subsurface.Furthermore,in a reductive environment,H2 facilitates the formation and diffusion of Ov while Ce-terminated surfaces develope.These results reveal dynamic atomic-scale interplay between the nanoceria surface and gas,thereby providing fundamental insights into the Ov-dependent reaction of nano-CeO_(2) during catalytic processes.

关键词： Ceria Direct observation In situ ETEM Oxygen vacancy Density function calculations Rareearths

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Hydroxylated metal–organic-layer nanocages anchoring single atomic cobalt sites for robust photocatalytic CO_(2) reduction

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Nano Research 2024年第4期17卷 2410-2419页

作者： weiyi Pan Zhihe wei yanhui Su Yuebin Lian Zhangyi Zheng Huihong Yuan Yongze Qin Xulan Xie Qianqian Bai Zhenyang Jiao wei Hua Jinzhou Chen Wenjun Yang Zhao Deng Yang Peng Soochow Institute for Energy and Materials Innovations College of EnergySoochow UniversitySuzhou 215006China Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province Soochow UniversitySuzhou 215006China School of Photoelectric Engineering Changzhou institute of technologyChangzhou 213032China Jiangsu Key Laboratory for Advanced Negative Carbon Technologies Soochow UniversitySuzhou 215123China

Assembly of two-dimensional(2D)metal–organic layers(MOLs)based on the hard and soft acid–base theorem represents an exquisite strategy for the construction of photocatalytic platforms in virtue of the highly exposed active sites,much improved mass transport,and greatly elevated stability.Herein,nanocages composed of MOLs are produced for the first time through a cosolvent approach utilizing zirconium-based UiO-66-(OH)2 as the structural precursor.To endow the catalytic activity for CO_(2) conversion,single atomic Co^(2+)sites are appended to the Zr-oxo nodes of the MOL cages,demonstrating a remarkable CO yield of 7.74 mmol·g^(-1)·h^(-1) and operational stability of 97.1%product retention after five repeated cycles.Such an outstanding photocatalytic performance is mainly attributed to the unique nanocage morphology comprising enormous 2D nanosheets for augmented Co^(2+)exposure and the abundant surface hydroxyl groups for local CO_(2) enrichment.This work underlines the tailoring of both metal–organic framework(MOF)morphology and functionality to boost the turnover rate of photocatalytic CO_(2) reduction reaction(CO_(2)RR).

关键词： photocatalytic CO_(2) reduction metal–organic layer nanocage single-atom catalyst co-catalyst

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Out-of-plane elastic buckling load and strength design of space truss arch with a rectangular section

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Frontiers of Structural and Civil Engineering 2022年第9期16卷 1141-1152页

作者： Senping WANG Xiaolong LIU Bo YUAN Minjie SHI yanhui wei Space Structures Research Center Guizhou UniversityGuiyang 550025China

The out-of-plane stability of the two-hinged space truss circular arch with a rectangular section is theoretically and numerically investigated in this paper.Firstly,the flexural stiffness and torsional stiffness of space truss arches are deduced.The calculation formula of out-of-plane elastic buckling loads of the space truss arch is derived based on the classical solution of out-of-plane flexural-torsional buckling loads of the solid web arch.However,since the classical solution cannot be used for the calculation of the arch with a small rise-span ratio,the formula for out-of-plane elastic buckling loads of space truss arches subjected to end bending moments is modified.Numerical research of the out-of-plane stability of space truss arches under different load cases shows that the theoretical formula proposed in this paper has good accuracy.Secondly,the design formulas to predict the out-of-plane elastoplastic stability strength of space truss arches subjected to the end bending moment and radial uniform load are presented through introducing a normalized slenderness ratio.By assuming that all components of space truss circular arches bear only axial force,the design formulas to prevent the local buckling of chord and transverse tubes are deduced.Finally,the bearing capacity design equations of space truss arches are proposed under vertical uniform load.

关键词： torsional stiffness strength design elastic buckling space truss arches out-of-plane

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Review of interface tailoring techniques and applications to improve insulation performance

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High Voltage 2022年第1期7卷 12-31页

作者： Mingxiao Zhu Jianyi Xue yanhui wei Guochang Li Guanjun Zhang College of New Energy China University of Petroleum(East China)QingdaoChina State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical EngineeringXi'an Jiaotong UniversityXi'anChina Institute of Advanced Electrical Materials Qingdao University of Science and TechnologyQingdaoChina

Interfaces between different materials,for instance,electrode-dielectrics and vacuum/air/SF6‐insulators and oilpaper,are universal in high‐voltage insulation systems.Targeted tailoring of the interfacial properties,e.***.chemical structures,micro‐/nanoscale morphology,the charge injection barrier,trap states,and surface conductivity,is thought to be an effective approach to improve insulation properties such as breakdown and flashover strength,corona/tracking resistance,and wettability.In this article,the authors review recent progress in interface tailoring methods and their application to improve various insulation properties.The potential application scenarios of interface tailoring in different facilities are first summarised,and the desired insulation properties of various applications are highlighted.Interface tailoring methods are classified as physical/chemical surface modification and surface coating(inorganic,organic and composite),and the features of different techniques are described in detail.The structure-property relationships between interfacial states and various microscopic parameters such as charge injection barrier,trap distribution and surface conductivity are discussed together with the tailoring mechanisms for different insulation properties.Finally,the future development prospects of interface tailoring methods and their applications,e.***.multi-functional coating and stimuli-response smart coating,are presented.

关键词： coating interface insulation

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Evaluation of new IPSS-Molecular model and comparison of different prognostic systems in patients with myelodysplastic syndrome

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Blood Science 2023年第3期5卷 187-195页

作者： Jiale Ma Yan Gu yanhui wei Xuee Wang Peixuan Wang Chunhua Song Zheng Ge Department of Hematology Zhongda HospitalSchool of MedicineSoutheast UniversityInstitute of Hematology Southeast UniversityNanjing 210009China Department of Hematology Xuzhou Central HospitalXuzhou 221009China Hershey Medical Center Pennsylvania State University Medical CollegeHersheyPAUSA Division of Hematology The Ohio State University Wexner Medical Centerthe James Cancer HospitalColumbusOHUSA

A risk-adapted treatment strategy is of crucial importance in patients with myelodysplastic syndromes(MDS).Previous risk prognostic scoring systems did not integrate molecular abnormalities.The new IPSS-Molecular(IPSS-M)model,combing genomic profiling with hematologic and cytogenetic parameters,was recently developed to evaluate the associations with leukemia-free survival(LFS),leukemic transformation,and overall survival(OS).However,it has not yet been widely validated in clinics.This study aims to further validate the prognostic power of IPSS-M based on real-world data and to compare the prognostic value of different scoring systems in patients with MDS.IPSS-M Web calculator was used to calculate a tailored IPSS-M score of the enrolled patient(N=255),and the risk category was defined correspondingly.We next compared the IPSS-M prognostic power to that of IPSS,IPSS-R,and WPSS.We found that IPSS-M risk classification was statistically significant for 3-year OS and LFS.Compared with other tools,IPSS-M was superior in sensitivity and accuracy for 3-year OS and LFS.The mapping C-index between IPSS-R and IPSS-M categories resulted in improved discrimination across the OS,but not LFS and leukemic transformation.The result of different treatment options indicated that allogeneic hematopoietic stem cell transplantation(allo-HSCT)can result in a better OS than those without allo-HSCT.In conclusion,IPSS-M was a valuable tool for risk stratification compared with other risk prognostic scoring systems.However,more studies should be conducted to explore the appropriate treatment options for different groups stratified by IPSS-M.

关键词： IPSS-Molecular myelodysplastic syndrome prognostic models

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Effect of graphene modified semi-conductive shielding layer on space charge accumulation in insulation layer for high-voltage direct current cable

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High Voltage 2022年第3期7卷 545-552页

作者： Guochang Li Xuejing Li Fan Zhang Xiaojian Liang Mingyue Liu yanhui wei Shengtao Li Chuncheng Hao Qingquan Lei Institute of Advanced Electrical Materials Qingdao University of Science and TechnologyQingdaoChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

Space charge accumulation in the insulation layer of high-voltage direct current(HVDC)cable is one of the key factors restricting the development of HVDC cable.The inner semi-conductive layer as an important structure of cable will affect the charge accumu-lation characteristics in the insulation layer.This work intends to explore the method of modifying the semi-conductive layer with graphene,to suppress charge accumulation in the insulation layer.First,the semi-conductive layer with different contents of Graphene(G)and carbon black(CB)are prepared.Second,the morphology and surface roughness of the cross section are analysed.Further,the effects of the semi-conductive layer on space charge accumulation of the insulation layer are studied by pulsed electro-acoustic method and thermal stimulation depolarisation current method.The experimental re-sults show that a moderate amount of graphene replacing CB can effectively reduce charge accumulation in the insulation layer and inhibit positive temperature coefficient(PTC)effect at the same time.The surface roughness of specimens decreases with the increase of G content from 0 to 3 phr(parts per hundreds of resin),when the CB content decreases from 25 to 10 phr,the surface roughness of specimen increases.The resistivity test shows that doping G can significantly inhibit the PTC effect of the semi-conductive layer.The volume resistivity of the semi-conductive layer decreases with the increase of G content and CB content.In addition,charge accumulation of the insulation layer rises and then drops under the action of the semi-conductive layer.

关键词： insulation conductive layer

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