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Tribological behavior of lubricant-impregnated porous polyimide

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Friction 2024年第4期12卷 711-725页

作者： Jinbang li Ningning ZHOU Janet s.s.WONG school of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Beijing Key Laboratory of Long-life Technology of Precise Rotation and Transmission Mechanisms Beijing Institute of Control EngineeringBeijing 100029China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK

Porous materials impregnated with lubricants can be used in conditions where limited lubricant is *** this work,three porous polyimides(PPI)with different densities were ***(PAO)impregnated PPI(iPPI)discs were rubbed against steel and sapphire *** operando observations of the iPPI-sapphire contacts show that oil is released under an applied load,forming a meniscus around *** at the outlet is created at high sliding *** amount of released oil increases with increasing PPI *** moduli,E*,estimated based on the actual contact size show that trapped oil in iPPIs contributes to load *** higher speeds,tribological rehydration of the contact occurs in low density iPPI,with that E*rises with *** high density PPIs,high speeds give a constantly high E*which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil *** of iPPI-steel contacts is governed by the mechanical properties of the PPI,the flow of the lubricant,and the roughness of the PPI *** low-and medium-density(highly porous,high roughness)PPIs,large amount of oil is released,and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological *** high density(low porosity)PPI,with lower roughness,hydrodynamic lubrication is achieved which gives the lowest *** results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness,stiffness,oil flow,and oil retentions.

关键词： polyimide porous material friction mechanism polymer limited lubrication

Editorial for the special Issue on Emerging Technology and Advanced Application of Nondestructive Detection for Power Equipment

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Chinese Journal of Electrical Engineering 2024年第1期10卷 1-2页

作者： li J. Mei H. li s. Tianjin University China Tsinghua shenzhen International Graduate school China Lanzhou Jiaotong University China

The rapid development of clean and renewable energy technologies represented by wind and solar energy,as well as the continuous growth of load demand,have put forward higher requirements for the safe operation of the power *** performance of power equipment based on traditional dielectric materials is often limited by various defects generated during molding,transportation,assembly,and operation,which cannot meet the reliability requirements of power systems in the new *** detection is an essential technical method in industrial development,which can detect and evaluate the defect and damage status of in-service equipment,key components,and materials without damaging the object.

关键词： service Application operation

Accuracy comparison and improvement for state of health estimation of lithium-ion battery based on random partial recharges and feature engineering

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Journal of Energy Chemistry 2024年第5期92卷 591-604页

作者： Xingjun li Dan Yu søren Byg Vilsen Daniel Ioan stroe Department of Energy Aalborg UniversityAalborg 9220Denmark Department of Mathematical sciences Aalborg UniversityAalborg 9220Denmark Walker Department of Mechanical Engineering The University of Texas at AustinAustinTX 78712USA

state of health(sOH)estimation of e-mobilities operated in real and dynamic conditions is essential and *** of existing estimations are based on a fixed constant current charging and discharging aging profiles,which overlooked the fact that the charging and discharging profiles are random and not complete in real *** work investigates the influence of feature engineering on the accuracy of different machine learning(ML)-based sOH estimations acting on different recharging sub-profiles where a realistic battery mission profile is *** features were extracted from the battery partial recharging profiles,considering different factors such as starting voltage values,charge amount,and charging sliding ***,features were selected based on a feature selection pipeline consisting of filtering and supervised ML-based subset *** linear regression(MLR),Gaussian process regression(GPR),and support vector regression(sVR)were applied to estimate sOH,and root mean square error(RMsE)was used to evaluate and compare the estimation *** results showed that the feature selection pipeline can improve sOH estimation accuracy by 55.05%,2.57%,and 2.82%for MLR,GPR and sVR *** was demonstrated that the estimation based on partial charging profiles with lower starting voltage,large charge,and large sliding window size is more likely to achieve higher *** work hopes to give some insights into the supervised ML-based feature engineering acting on random partial recharges on sOH estimation performance and tries to fill the gap of effective sOH estimation between theoretical study and real dynamic application.

关键词： Feature engineering Dynamic forklift aging profile state of health comparison Machine learning lithium-ion batteries

Carbon allocation in Picea jezoensis:Adaptation strategies of a non-treeline species at its upper elevation limit

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Forest Ecosystems 2024年第3期11卷 347-357页

作者： Renkai Dong Na li Mai-He li Yu Cong Haibo Du Decai Gao Hong s.He Key Laboratory of Geographical Processes and Ecological security in Changbai Mountains Ministry of EducationSchool of Geographical SciencesNortheast Normal UniversityChangchun130024China school of Natural Resources University of MissouriColumbiaMO65211USA swiss Federal Institute for Forest Snow and Landscape Research WSL8903BirmensdorfSwitzerland Northeast Institute of Geography and Agricultural Ecology Chinese Academy of SciencesChangchun130102China school of life science Hebei UniversityBaoding071002China

Understanding the physiological adaptations of non-treeline trees to environmental stress is important to understand future shifts in species composition and distribution of current treeline *** aim of the present study was to elucidate the mechanisms of the formation of the upper elevation limit of non-treeline tree species,Picea jezoensis,and the carbon allocation strategies of the species on Changbai *** employed the^(13)C in situ pulse labeling technique to trace the distribution of photosynthetically assimilated carbon in Picea jezoensis at different elevational positions(tree species at its upper elevation limit(TsAUE,1,700 m a.s.l.)under treeline ecotone;tree species at a lower elevation position(TsALE,1,400 m a.s.l.).We analyzed^(13)C and the non-structural carbohydrate(NsC)concentrations in various tissues following *** findings revealed a significant shift in carbon allocation in TsAUE compared to *** was a pronounced increase inδ^(13)C allocation to belowground components(roots,soil,soil respiration)in TsAUE compared to ***,the C flow rate within the plant-soil-atmosphere system was faster,and the C residence time in the plant was shorter in *** trends indicate enhanced C sink activity in belowground tissues in TsAUE,with newly assimilated C being preferentially directed there,suggesting a more conservative C allocation strategy by *** at higher elevations under harsher *** a strategy,prioritizing C storage in roots,likely aids in withstanding winter cold stress at the expense of aboveground growth during the growing season,leading to reduced growth of TsAUE compared to *** results of the present study shed light on the adaptive mechanisms governing the upper elevation limits of non-treeline trees,and enhances our understanding of how non-treeline species might respond to ongoing climate change.

关键词： ^(13)C pulse labeling Carbon distribution Non-structural carbohydrates(NsC) Non-treeline species sink activity stressful environments Upper elevation limit

Anthropogenic mineral generation and its potential resource supply:The case of niobium

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science China Earth sciences 2024年第8期67卷 2583-2591页

作者： Xianlai ZENG Moisés Gómez Mahmoud BAKRY Yong GENG Jinhui li school of Environment Tsinghua UniversityBeijing 100084China school of Environmental science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China school of International and Public Affairs Shanghai Jiao Tong UniversityShanghai 200030China

The strategy of carbon neutrality is reshaping the global landscape of resource flow and *** the final sink of geological minerals,the proliferated anthropogenic minerals,also called secondary resources,play an increasingly important role in resource supply *** is a critical metal that lacks full concern for its *** fundamental principle of niobium circularity is to recycle and maintain the material as close to the manufacturing process as *** we estimate the niobium-containing applications lost at their end-of-life,underscoring the imperative to minimize such ***,we elucidate the extraction processes for scrap and alloy quantities throughout the industry's *** from anticipated waste generated by the majority of niobium applications,a forecast indicates a potential loss of approximately 168 kt by 2090 in the absence of ***,with a recycling efficiency of 90%for niobium,the projected loss diminishes to approximately 16 *** delve into the significance of niobium's circular economy and explore various aspects that demand further investigation for a seamless transition from linear to circular practices.

关键词： Niobium Anthropogenic mineral Circular economy Recycling sustainability

Hypoxic and temporal variation in the endocrine disrupting toxicity of perfluorobutanesulfonate in marine medaka(Oryzias melastigma)

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Journal of Environmental sciences 2024年第2期136卷 279-291页

作者： Baili sun Jing li Yachen Bai Xiangzhen Zhou Paul K.s.Lam lianguo Chen state Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China University of Chinese Academy of sciences Beijing 100049China Office of the President Hong Kong Metropolitan University30 Good Shepherd StreetKowloonHong Kong SARChina

Perfluorobutanesulfonate(PFBs)is an emerging pollutant capable of potently disrupting the sex and thyroid endocrine systems of ***,the hypoxic and temporal variation in PFBs endocrine disrupting toxicity remain largely *** the present study,adult marine medaka were exposed to environmentally realistic concentrations of PFBs(0 and 10μg/L)under normoxia or hypoxia conditions for 7 days,aiming to explore the interactive behavior between PFBs and *** addition,PFBs singular exposure was extended till 21days under normoxia to elucidate the time-course progression in PFBs *** results showed that hypoxia inhibited the growth and caused the suspension of egg spawn regardless of PFBs *** regard to the sex endocrine system,7-day PFBs exposure led to an acute stimulation of transcriptional profiles in females,which,subsequently,recovered after the 21-day *** potency of hypoxia to disturb the sex hormones was much stronger than PFBs.A remarkable increase in estradiol concentration was noted in medaka blood after hypoxia *** in sex endocrinology of coexposed fish were largely determined by hypoxia,which drove the formation of an estrogenic *** further enhanced the endocrine disrupting effects of ***,the hepatic synthesis of vitellogenin and choriogenin,two commonly used sensitive biomarkers of estrogenic activity,failed to initiate in response to the estrogen *** to sex endocrine system,disturbances in thyroidal axis by PFBs or hypoxia were relatively ***,the present findings will advance our toxicological understanding about PFBs pollutant under the interference of hypoxia.

关键词： Perfluorobutanesulfonate(PFBs) Aquatic hypoxia Temporal toxicity Combined exposure Endocrine disruption Marine medaka

synergistic Co-doping effect of CNTs and PVP in Na_(4)MnCr(PO_(4))3 cathode as a strategy for improving the electrochemical performance of sIBs

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Chinese Chemical Letters 2024年第2期35卷 539-543页

作者： Ruoyu Chen Denys s.Butenko shilin li Xinyu Zhang Guangshe li Igor V.Zatovsky Wei Han College of Physics State Key Laboratory of Inorganic Synthesis and Preparative ChemistryInternational Center of Future ScienceJilin UniversityChangchun 130012China Academy for Advanced Interdisciplinary studies Southern University of Science and TechnologyShenzhen 518055China state Key Laboratory of Inorganic synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchun 130012China F.D.Ovcharenko Institute of Biocolloidal Chemistry NAS UkraineKyiv 03142Ukraine

In order to solve the contradiction between the rapidly growing energy demand and the excessive exploitation of fossil fuels,it is urgent to research and develops more environmentally friendly and efficient energy storage ***,the development of high-performance cathode materials to enhance the energy density of sIB is currently one of the most important topics of scientific *** high-voltage and low-cost cathode material for sIBs,a composite of carbon-coated Na_(4)MnCr(PO_(4))_(3)(NAsICON-type),polyvinylpyrrolidone(PVP),and modified carbon nanotubes(CNTs)is prepared by sol-gel and freeze-drying *** to the high conductivity of CNTs,the conductivity of the composite is significantly improved,and its initial capacity is increased to 114 mAh/g at 0.5 C and 96 mAh/g at 5 C(Mn^(2+)/Mn^(4+)conversion for voltage windows 1.4-4.3 V).Moreover,the multi-electrons transfer of Cr^(3+)/Cr^(4+) and Mn^(2+)/Mn^(4+) can provide a high capacity of 165 mAh/g at 0.1 C and 102 mAh/g at 5 C in the high voltage window of 1.4-4.6 ***,PVP can effectively inhibit the Jahn-Teller effect caused by Mn ion,making the composite have more excellent high-rate performance and *** addition,GITT,EIs and CV curves were drawn to better reveal the excellent kinetic properties of Na_(4)MnCr(PO_(4))_(3)@C@PVP@CNT cathode,and the mechanism of its performance improvement is deeply studied and ***,the co-doping of CNTs and PVP is a simple way to high conductivity and fast charging of cathode materials for sIBs.

关键词： sodium-ion batteries Na_(4)MnCr(PO_(4))_(3) Carbon nanotubes Polyvinylpyrrolidone synergistic effect

semi-automated detection of rangeland runoff and erosion control berms using high-resolution topography data

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International soil and Water Conservation Research 2024年第1期12卷 217-226页

作者： li li Changjiang River scientific Research Institute of Changjiang Water Resources Commission Wuhan430010China Research Center on Mountain Torrent&Geologic Disaster Prevention Ministry of Water ResourcesWuhan430010China University of Arizona School of Natural Resources and the EnvironmentTucsonAZ85719USA

An inventory of topographic modifications is essential to addressing their impacts on hydrological and morphological processes in human-altered ***,such inventories are generally *** study presents two workflows for semi-automatic detection of linear earthen runoff and erosion control berms in rangelands using high-resolution topographic *** workflows consist of initial object identification by applying either morphological grayscale reconstruction(MGR)or the Geomorphon(GEO)method,followed by identification refinements through filters based on objects’horizontal and vertical *** sites were selected within the Altar Valley,Arizona,in the southwestern United *** site was used for developing workflows and optimizing filter thresholds,and the other two sites were used to validate *** results showed that:1)The MGR-based workflow methodology could produce final precision and detection rates of up to 92%and 75%,respectively,and take less than 5 s for a 10.1 km^(2) site;2)The workflow based on the MGR method yielded greater identification accuracy than did the GEO workflow;3)Object length,orientation,and eccentricity were important characteristics for identifying earthen berms,and are sensitive to general channel flow direction and berm shape;4)Manual interrogation of topographic data and imagery can significantly improve identification precision *** proposed workflows will be useful for developing inventories of runoff and erosion control structures in support of sustainable rangeland management.

关键词： Earthen berm Rangeland Grayscale morphological reconstruction Geomorphon liDAR

stretchable on-skin touchless screen sensor enabled by ionic hydrogel

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Nano Research 2024年第5期17卷 4462-4470页

作者： Tianxing Feng Dan ling Chaoyue li Wentao Zheng shichuan Zhang Chang li Artem Emel’yanov Alexander s.Pozdnyakov lijun Lu Yanchao Mao Key Laboratory of Materials Physics of Ministry of Education School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450001China A.E.Favorsky Irkutsk Institute of Chemistry Siberian Branch of the Russian Academy of SciencesIrkutsk 664033Russian Federation

screen sensors are the most commonly used human-machine interfaces in our everyday life,which have been extensively applied in personal electronics like *** screen sensors are attracting growing interest due to their distinct advantages of high interaction freedom,comfortability,and hand ***,the material compositions of current touchless screen sensors are rigid and fragile,hardly meeting the needs of wearable and stretchable on-skin electronics ***,these touchless screen sensors are also restricted by high power consumption,limited gesture types of recognition,and the requirement of light ***,we report a stretchable on-skin touchless screen sensor(OTss)enabled by an ionic hydrogel-based triboelectric nanogenerator(TENG).Compared with current touchless screen sensors,the OTss is stretchable,self-powered,and competent to recognize diverse gestures by making use of charges naturally carried on fingers without the need of sufficient light *** on-skin noncontact screen operating system is further demonstrated on the basis of the OTss,which could unlock a cellphone interface in touchless operation mode on the human *** work for the first time introduces the on-skin touchless concept to screen sensors and offers a direction to develop new-generation screen sensors for future cellphones and personal electronics.

关键词： human-machine interface stretchable ionic hydrogel triboelectric nanogenerator self-powered sensor