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Structural Surface Crack Monitoring Method Based on Electrical Potential Technique and Modern Surface Technology

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 601-606页

作者： CUI Ronghong HE Yuting YU Zhiming LI Hongpeng shu wenjun DU Jinqiang Engineering College Air Force Engineering University Xi＇an 710038 China State Key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China 94655 Unit The Chinese People＇s Liberation Army Wuhu 241007 China

Crack monitoring plays a great role in modern structural health monitoring, however, most of the conventional crack inspections have disadvantages in terms of the accuracy, expense, reliability, durability and level of instrumentation required. Thus, development of a simple and reliable crack inspection technique that allows continuous monitoring has been desired. In this paper, electrical potential technique and modern surface technology are employed together to develop a new structural surface crack monitoring method. A special crack monitoring coating sensor based on electrical potential technique was deposited on the hot spot of the structure by modern surface technology. The sensor consists of three layers： the isolated layer, the sensing layer and the protective layer. The isolated layer is prepared by anodic oxidation technology, the sensing layer is made of ion plated copper, and the protective layer is made of silicone. The thickness of each layer is at micrometer magnitude. The electrical conductivity of the sensor is very stable, and the fatigue performance of the specimen with or without coating sensor is nearly unchanged. The crack monitoring experiment result shows that there are two sudden rises of the coating sensor electrical potential values, corresponding to different stages of the crack initiation and propagation. Since the width of the surface coating sensor is only 0.5 mm, this crack monitoring sensor can detect the propagation of cracks less than 0.5 mm long. The method proposed takes the simplicity of electrical potential technique and can monitor surface crack of nearly all kinds of structures precisely. The results of this paper may form the basis of a new crack monitoring system.

关键词： crack monitoring electrical potential technique surface technology coating sensor LY12-CZ aluminum alloy

Effects of urbanization on daily temperature extremes in North China

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Journal of Geographical Sciences 2014年第2期24卷 349-362页

作者： SI Pengt ZHENG Zuofang REN Yu LIANG Dongpo LI Mingcai shu wenjun Tianjin Meteorological Information Center Tianjin Meteorological Bureau Tianjin 300074 China Institute of Urban Meteorology China Meteorological Administration Beijing 100089 China Tianjin Climate Center Tianjin Meteorological Bureau Tianjin 300074 China Beijing Climate Center Beijing Meteorological Bureau Beijing 100089 China

The regional changes of daily temperature extremes in North China caused by ur- banization are studied further from observed facts and model estimates on the basis of ho- mogenized daily series of maximum and minimum temperature observations from 268 mete- orological stations, NCEP/DOE AMIP- Ⅱ reanalysis data （R-2）, and the data of simulations by regional climate model （RegCM3）. The observed facts of regional warming on long time scales are obtained by analyzing the indices of temperature extremes during two time periods of 1961-2010 and 1951-2010. For urbanization effect, the contributions to decreases in an- nual and winter diurnal temperature range （DTR） are 56.0% and 52.9%, respectively, and increases in the lowest minimum temperature （TNn） are 35.7% and 26.2% by comparison of urban and rural observations. Obtained by R-2 data with observations for contrast, on the other hand, increase in the number of annual warm nights （TN90p） contributed by urbaniza- tion is 60.9%. And observed facts of regional warming in daily temperature extremes are also reflected in the simulations, but what difference is urbanization progress at rural areas in North China would be prominent in the next few years relative to urban areas to some extent from model estimates.

关键词： urbanization daily temperature extremes significant contribution North China

Impacts of the Urban Spatial Landscape in Beijing on Surface and Canopy Urban Heat Islands

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Journal of Meteorological Research 2022年第6期36卷 882-899页

作者： Yonghong LIU Yongming XU Yeping ZHANG Xiuzhen HAN Fuzhong WENG Chunyi XUAN wenjun shu CMA Earth System Modeling and Prediction Centre China Meteorological Administration(CMA)Beijing 100081 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 School of Remote Sensing and Geomatics Engineering Nanjing University of Information Science&TechnologyNanjing 210044 National Satellite Meteorological Centre China Meteorological AdministrationBeijing 100081 Beijing Municipal ClimateCentre Beijing Meteorological ServiceBeijing 100089

How does the urban spatial landscape(USL)pattern affect the land surface urban heat islands(SUHIs)and canopy urban heat islands(CUHIs)?Based on satellite and meteorological observations,this case study compares the impacts of the USL pattern on SUHI and CUHI in the central urban area(CUA)of Beijing using the satellite land-surface-temperature product and hourly temperature data from automatic meteorological stations from 2009 to *** USL metrics—building height(BH),building density(BD),standard deviation of building height(BSD),floor area ratio(FAR),frontal area index(FAI),roughness length(RL),sky view factor(SVF),urban fractal dimension(FD),vegetation coverage(VC),impervious coverage(IC),and albedo(AB)—with a 500-m spatial resolution in the CUA are extracted for comparative *** results show that SUHI is higher than CUHI at night,and SUHI is only consistent with CUHI at spatial-temporal scales at night,particularly in ***,all 11 metrics are strongly correlated with both the SUHI and CUHI at night,with stronger correlation between most metrics and ***,AB,and SVF have the greatest impact on both the SUHI and *** SUHI and CUHI values tend to appear in areas with BD≥0.26,VC≤0.09,AB≤0.09,and SVF≤*** summer,most metrics have a greater impact on the SUHI than CUHI;the opposite is observed in *** variation is affected primarily by VC in summer and by VC and AB in winter,which is different for the CUHI *** collective contribution of all 11metrics to SUHI spatial variation in summer(61.8%)is higher than that to CUHI;however,the opposite holds in winter and for the entire year,where the cumulative contribution of the factors accounts for 66.6%and 49.6%,respectively,of the SUHI variation.

关键词： surface urban heat island canopy urban heat island vegetation coverage albedo sky view factor building density Beijing

How does supergravity affect combustion?

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Acta Mechanica Sinica 2024年第6期40卷 39-40页

作者： wenjun Kong Zheng Chen School of Astronautics Beihang UniversityBejing 102206China State Key Laboratory of Turbulence and Complex System Cllege of EngineeringPeking Universy Beijing 100871Chin

It is well known that gravity may have a profound impact on the combustion process under certain conditions[1].The densities of the gaseous combustion products are typically 5-12 times lower than those of *** normal gravity conditions,the density difference generates buoyant forces that drive the flow,which affects the combustion process through flow-transport-chemistry *** example,the buoyant convection in normal gravity causes the candle flame to be shaped like a teardrop while spherical candle flame is observed in ***,microgravity combustion has drawn great attention.A series of combustion experiments have been and will be conducted in the International Space Station and Chinese Space *** fact,significant progress has been made in microgravity *** example,the discovery of steadily burning cool flames[2]in microgravity experiments was regarded as one of the"20 Breakthroughs from 20 Years of Science aboard the International Space Station".

关键词： interaction. reactant typically

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适用于UH模型的单元破坏修正方法

北京航空航天大学学报 2017年第4期43卷 667-675页

作者：罗汀舒文俊姚仰平北京航空航天大学交通科学与工程学院北京100083

在采用UH模型的用户材料子程序(UMAT)进行有限元计算过程中时常会出现局部单元破坏的情况,主要包括拉裂和剪坏,这种破坏应力状态的存在不仅会使得计算结果不合理,也会降低有限元计算的稳定性。针对采用UH模型UMAT进行有限元计算时遇到... 详细信息

在采用UH模型的用户材料子程序(UMAT)进行有限元计算过程中时常会出现局部单元破坏的情况,主要包括拉裂和剪坏,这种破坏应力状态的存在不仅会使得计算结果不合理,也会降低有限元计算的稳定性。针对采用UH模型UMAT进行有限元计算时遇到的局部单元破坏问题,根据一定的假设条件,并结合不同坐标系下的应力变换关系,推导得到适用于UH模型的三维问题单元破坏修正公式;采用FORTRAN语言编写出相应的子程序,将其嵌入UH模型UMAT中,以消除采用UH模型进行有限元计算时出现的不合理的破坏应力状态,提高UH模型UMAT有限元计算的稳定性,并通过有限元模拟基坑开挖的例子验证本文所提的单元破坏修正方法的有效性和合理性。

关键词： UH模型 UMAT 有限元拉裂剪坏破坏修正

A Fully-Integrated Memristor Chip for Edge Learning

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Nano-Micro Letters 2024年第9期16卷 123-127页

作者： Yanhong Zhang Liang Chu wenjun Li School of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018People’s Republic of China

It is still challenging to fully integrate computing in memory chip as edge learning *** recent work published on Science,a fully-integrated chip based on neuromorphic memristors was developed for edge learning as artificial neural networks with functionality of synapses,dendrites,and somas.A crossbar-array memristor chip facilitated edge learning including hardware realization,learning algorithm,and cycle-parallel sign-and threshold-based learning(STELLAR)*** motion control and demonstration platforms were executed to improve the edge learning ability for adapting to new scenarios.

关键词： Computing in memory Edge learning Fully-integrated chip

Recent progress on copper catalysts with different surface states for CO_(2)electroreduction

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Journal of Energy Chemistry 2024年第1期88卷 10-27,I0001页

作者： wenjun Zhang Yang Yang Donggang Guo Lu Liu Tianjin Key Laboratory of Environmental Remediation and Pollution Control College of Environmental Science and EngineeringNankai UniversityTianjin 300350China Shanxi Laboratory for Yellow River College of Environment and ResourceShanxi UniversityTaiyuan 030006ShanxiChina

The electrochemical carbon dioxide reduction reaction(eCO_(2)RR),which converts CO_(2)into various hydrocarbons or alcohols,has been extensively researched because it promises a sustainable energy ***,only copper(Cu)can currently achieve stable and efficient hydrocarbon conversion in the eCO_(2)***,understanding the catalytic mechanisms and summarizing the research progress on synthesis strategies of Cu catalysts are essential for the eCO_(2)*** paper reviews Cu catalysts with different surface states of Cu catalysts:oxide-derived Cu,Cu nanoparticles,Cu single atoms,and Cu *** then reviews the development and progress of different Cu-catalyst preparation methods in recent years,focusing on the activity and selectivity of *** revealing the tendencies of catalytic selection and deep reactive mechanisms of Cu catalysts with four different surface states,this review can guide the subsequent construction of catalysts and provides an understanding of catalytic mechanisms.

关键词： eCO_(2)RR Oxide-derived Cu Cu nanoparticles Cu single atoms Cu nanoclusters

Stress-strain relationship for reactive powder concrete with recycled powder under uniaxial compression

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1015-1027页

作者： Peng ZHU Yunming ZHU wenjun QU Liyu XIE College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghai 200092China

The recycled powder(RP)from construction wastes can be used to partially replace cement in the preparation of reactive powder *** this paper,reactive powder concrete mixtures with RP partially replacing cement,and natural sand instead of quartz,are *** curing is used,instead of steam curing that is normally requested by standard for reactive powder *** influences of RP replacement ratio(0%,10%,20%,30%),silica fume proportion(10%,15%,20%),and steel fiber proportion(0%,1%,2%)are *** effects of RP,silica fume,and steel fiber proportion on compressive strength,elastic modulus,and relative absorption energy are analyzed,and theoretical models for compressive strength,elastic modulus,and relative absorption energy are established.A constitutive model for the uniaxial compressive stress-strain relationship of reactive powder concrete with RP is *** the increase of RP replacement ratio from 0% to 30%,the compressive strength decreases by 42% and elastic modulus decreases by 24%.

关键词： recycled powder reactive powder concrete elastic modulus relative absorbed energy stress-strain relationship

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长距离大倾角富水曲线斜井施工技术

现代隧道技术 2010年第6期47卷 71-76页

作者：舒文军中铁十二局集团第三工程有限公司太原030024

雅泸高速公路大相岭隧道2#通风斜井存在距离长、断面大、坡度陡、涌水量大等施工难题,难以完全按照传统的施工方法进行施工。在确保安全的前提下,通过对大相岭隧道2#通风斜井各道施工工序的实践论证,合理地选择了有轨运输配套设备,建立... 详细信息

雅泸高速公路大相岭隧道2#通风斜井存在距离长、断面大、坡度陡、涌水量大等施工难题,难以完全按照传统的施工方法进行施工。在确保安全的前提下,通过对大相岭隧道2#通风斜井各道施工工序的实践论证,合理地选择了有轨运输配套设备,建立了低压接力泵站与移动泵站相结合的排水系统,采用5 t慢速卷扬机和3×4滑轮组组成的牵引系统牵引大吨位衬砌台车,有效地解决了长距离、大倾角、曲线、富水斜井掌子面的出碴、排水和二次衬砌等问题,加快了隧道施工进度,减少了工程投资,拓展、丰富了斜井施工领域,对促进我国乃至世界斜井施工技术发展具有重要意义。

关键词：通风斜井富水台阶法有轨运输分级排水