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Optimization of Cross-sectional Shapes of the Bi-2223/Ag Wires before Flat Rolling

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Chinese Journal of Mechanical Engineering 2009年第6期22卷 890-895页

作者： LU Yongjin ZENG Pan lei liping SUN Jianfeng Department of Mechanical Engineering Tsinghua University Beijing 100084 China Key Laboratory for Advanced Materials Processing Technology of Ministry of Education Tsinghua University Beijing 100084 China Innova Superconductor Technology Co. Ltd. Beijing 100176 China

Rolling process plays an important role in the manufacture of Bi-based high temperature superconductor tapes, and the plastic flow regularities of the superconducting wires during deformation will directly affect the ultimate quality of the tapes. In order to investigate the effect of cross-sectional shapes before fiat rolling on the performance and homogeneity of the tapes, some numerical models of Bi-2223/Ag wires with different cross-sectional shapes including circular, square, elliptical and racetrack cross-sections are constructed during the rolling process. By comparing the relative density, logarithmic strain ratio and length-width ratio on the filaments, it is revealed that Bi-2223/Ag wire with special-shaped cross-section can achieve better conductivity than the round wire, in particular, the racetrack cross-sectional wire has the second best performance among four wires. Based on material processability and experimental condition, tri-pass racetrack drawing technique is employed to optimize the process and obtain racetrack cross-sectional wire. The rolling process of Bi-2223/Ag wire with racetrack cross-section causes more intensive deformation of filaments in the center of the tape and achieves the filaments with larger length-width ratio. Also, the deformation distribution of filaments verifies the numerical results. Consequently, the racetrack drawing technique can be utilized for a reference during the mechanical processing and to increase the current transmission capacities of Bi-2223/Ag tapes.

关键词： rolling cross-sectional shape filament modelling

NUMERICAL SIMULATION OF MECHANICAL BEHAVIORS OF SUPERCONDUCTING POWDER BSCCO (BiSrCaCuO)

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Chinese Journal of Mechanical Engineering 2007年第3期20卷 59-61页

作者： ZHAO Yinghong lei liping ZENG Pan Key Laboratory for Advanced Materials Processing Technology of Ministry of Education Beijing 100084 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

An equivalent continuum method and a deformable discrete method to describe the mechanical behaviors of superconducting powder BSCCO （BiSrCaCuO） aggregate are studied syste-matically. The equivalent continuum model idealizes the aggregation of the powder as an equivalent continuum material. The powder aggregate yielding is caused by not only the deviatoric stress but also the hydrostatic stress and the modified Drucker-Prager/Cap model is adopted to describe the mechanical behaviors of BSCCO powder aggregate in continuum method. The deformable discrete model is known as a direct model, which considers the discrete nature of the powder particles. Its framework encompasses the local behaviors between the particles, such as particles contact, sliding and rolling. Based on commercial finite element software ABAQUS, the equivalent continuum model and the deformable discrete model are used to simulate the confined compression of superconducting powder BSCCO, and the numerical results show agreement with experimental results, which verify the correctness of these built models. Compared with the equivalent continuum model based on macroscopic statistics method, the deformable discrete model can present the microscopic information during processing and can describe the nature of mechanical behaviors of superconducting powder BSCCO. But from an industrial viewpoint, the equivalent continuum model has a definitive edge over the microscopic models in that the gross behavior of the powder mass can be modeled and simulated on an industrial scale.

关键词： BSCCO(BiSrCaCuO) Mechanical behaviour Discrete method Continuum method

Local equivalent welding element to predict the welding deformations of plate-type structures

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Science China(Technological Sciences) 2008年第9期51卷 1502-1506页

作者： ZENG Pan GAO Yi lei liping Department of Mechanical Engineering Tsinghua UniversityKey Laboratory for Advanced Materials Processing TechnologyMinistry of Education of ChinaBeijing 100084China

Considering the Heat Affected Zone (HAZ) of welding joint, the residual strain be-haviors of material under constraint and temperature circulation, as well as the activating mechanism of welding process, this paper addresses a new type welding element for numerical simulation of welding deformation, which is called the LEWE (the local equivalent welding element). This element can describe the basic char-acteristics of welded seam: the local position points of inherent strain, the equiva-lent size, the bending radius (or bending angle) from inherent strain, etc. It could be used to predict the welding deformation of plate-type structure. The comparisons between the computed deflection of welded plate and its experiment measurement are present. The results showed that the LEWE possesses a potential to simulate the deformation of welding process high-efficiently and precisely.

关键词： welding deformation local equivalency welding element

INFLUENCE OF ROLL DIAMETERS ON DEFORMATION BEHAVIOUR OF HIGH TEMPERATURE SUPERCONDUCTING TAPE

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Chinese Journal of Mechanical Engineering 2007年第4期20卷 75-78页

作者： lei liping ZHAO Yinghong ZENG Pan Key Laboratory for Advanced Materials Processing Technology Beijing 100084 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

During plastic process, the material flow is strongly influenced by the contact area between deformed workpiece and die. In rolling process, difference of roll diameter makes the contact area between roll and deformed tape different, which leads to different material flow and the distribution of powder density. A numerical modelling of the first rolling process for 61-filament high temperature superconducting tape is constructed and the influences of roll diameters on deformation behavior of the tape are discussed. It can be found that the BiSrCaCuO （BSCCO） powder in the center of the tape has higher relative density than those in the periphery of the tape during rolling process. With the increase of roll diameter, the length of the contact arc in the roll gap expands which lead to the increasing of transversal strain and the decreasing of the related longitudinal strain. It makes the value of longitudinal strain ratio decrease gradually, which decreases the possibility of occurrence of the transversal shear band, simultaneously it increases the risk of occurrence of longitudinal crack.

关键词： Roll diameter Rolling process Filament Relative density

Spatial distribution and inducement of collapsed buildings in Yushu earthquake based on remote sensing analysis

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Science China Earth Sciences 2010年第6期53卷 794-796页

作者： HuaDong Guo Bing Zhang liping lei Li Zhang Yu Chen Chinese Acad Sci Ctr Earth Observat & Digital Earth Beijing 100190 Peoples R China

At 7:49 a.m. on April 14th, 2010, an earthquake of 7.1 on the Richter scale occurred in Yushu County, Yushu Tibetan Autonomous Prefecture in Qinghai Province. There was great loss of property and life.

关键词： houses collapse Tibetan damages Qinghai Richter quake rupture foundations disaster

Specific patterns of XC02 observed by GOSAT during 2009-2016and assessed with model simulations over China

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Science China Earth Sciences 2020年第3期63卷 384-394页

作者： Nian BIE liping lei Zhonghua HE Zhaocheng ZENG Liangyun LIU Bing ZHANG Bofeng CAI Key Laboratory of Digital Earth Science Institute ofRemote Sensing and Digital EarthChinese Academy of SciencesBeijing 100094China University of Chinese Academy of Sciences Beijing 100094China Division of Geological and Planetary Sciences California Institute of TechnologyPasadena CA91125USA The Center for Climate Change and Environmental Policy Chinese Academy for Environmental PlanningMinistry of Environmental ProtectionBeijing 100012China

Spatiotemporal patterns of column-averaged dry air mole fraction of CO2(XCO2)have not been well characterized on a regional scale due to limitations in data availability and *** paper addresses these issues by examining such patterns in China using the long-term mapping XCO2 dataset(2009-2016)derived from the Greenhouse gases Observing SATellite(GOSAT).XCO2 simulations are also constructed using the high-resolution nested-grid GEOS-Chem *** following results are found:Firstly,the correlation coefficient between the anthropogenic emissions and XCO2 spatial distribution is nearly zero in summer but up to 0.32 in ***,on average,XCO2 increases by 2.08 ppm every year from2010 to 2015,with a sharp increase of 2.6 ppm in ***,in the analysis of three typical regions,the GOSAT XCO2 time series is inbetter agreement with the GEOS-Chem simulation of XCO2 in the Taklimakan Desert region(the least difference with bias 0.65±0.78 ppm),compared with the northern urban agglomerationregion(-1.3±1.2 ppm)and the northeastern forest region(-1.4±1.4 ppm).The results are likely attributable to uncertainty in both the satellite-retrieved XCO2 data and the model simulation data.

关键词： GEOS-Chem GOSAT OCO-2 Specific pattern XCO2

Investigation on drawing process of Bi-2223/Ag wires using racetrack-type dies:Simulation and experiments

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Science China(Technological Sciences) 2009年第8期52卷 2255-2262页

作者： LU YongJin ZENG Pan lei liping QU TiMing FANG Gang SUN JianFeng Key Laboratory for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Innova Superconductor Technology Co.Ltd. Beijing 100176China

The traditional rolling process of Bi-2223/Ag wires with circular sections is an inhomogeneous process. For the purpose of achieving a uniform filaments distribution, a novel technique for round wire through racetrack-type dies during the last several passes of drawing is necessarily brought forward. In order to investigate the processing behaviors of superconducting filaments, a numerical model for the three passes of racetrack drawing was constructed, and subsequently, the optimization of three racetrack-type dies was designed based on the simulation results. Then the three passes of racetrack drawing was applied to fabricate Bi-2223/Ag tape and the density distribution of each filament of the wire was studied by Vickers microhardness. The experimental results showed that the racetrack drawing can obtain dense superconducting filaments, and improve the mechanical properties and critical current of the final tape.

关键词： racetrack-type die Bi-2223/Ag modelling

China's sizeable and uncertain carbon sink: a perspective from GOSAT

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Chinese Science Bulletin 2014年第14期59卷 1547-1555页

作者： Li Zhang Jingfeng Xiao Li Li liping lei Jing Li Key Laboratory of Digital Earth Science Institute of Remote Sensing and Digital EarthChinese Academy of Sciences Earth Systems Research Center Institute for the Study of EarthOceansand SpaceUniversity of New HampshireDurhamNH 03824USA State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University

Despite the agreement that China’s terrestrial ecosystems can provide a carbon sink and offset carbon dioxide(CO2)emissions from fossil fuels,the magnitude and spatial distribution of the sink remain *** quantification of the carbon sequestration capacity of China’s terrestrial ecosystems has profound scientific and policy ***,we report on the magnitude and patterns of China’s terrestrial carbon sink using the global monthly CO2flux data product from the Greenhouse gases Observing SATellite(GOSAT),the world’s first satellite dedicated to global greenhouse gas *** use the first year’s data from GOSAT(June 2009–May2010)that are currently available to assess China’s biospheric carbon *** results show that China’s terrestrial ecosystems provide a carbon sink of-0.21 Pg C *** consumption of fossil fuels in China leads to carbon dioxide emissions of 1.90 Pg C a-1into the atmosphere,approximately 11.1%of which is offset by China’s terrestrial ***’s terrestrial ecosystems play a significant role in offsetting fossil fuel emissions and slowing down the buildup of CO2in the *** analysis based on GOSAT data offers a new perspective on the magnitude and distribution of China’s carbon *** results show that China’s terrestrial ecosystems provide a sizeable and uncertain carbon sink,and further research is needed to reduce the uncertainty in its magnitude and distribution.

关键词：二氧化碳中国陆地生态系统 CO2通量化石燃料观测卫星温室气体排放量

Global land 1° mapping dataset of XCO_(2) from satellite observations of GOSAT and OCO-2 from 2009 to 2020

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Big Earth Data 2023年第1期7卷 170-190页

作者： Mengya Sheng liping lei Zhao-Cheng Zeng Weiqiang Rao Hao Songd Changjiang Wu Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina College of Resources and Environment University of Chinese Academy of SciencesBeijingChina Division of Geological and Planetary Sciences California Institute of TechnologyPasadenaCaliforniaUSA School of Earth Sciences China University of GeosciencesBeijingChina

A global mapping data of atmospheric carbon dioxide(CO_(2))concen-trations can help us to better understand the spatiotemporal varia-tions of CO_(2) and the driving factors of the variations to support the actions for emissions reduction and *** gases satel-lites that measure atmospheric CO_(2),such as the Greenhouse Gases Observing Satellite(GOSAT)and Orbiting Carbon Observatory(OCO-2),have been providing global observations of the column averaged dry-air mole fractions of CO_(2)(XCO_(2))since ***,these XCO_(2) retrievals are irregular in space and time with many *** this paper,we mapped a global spatiotemporally continuous XCO_(2) data-set(Mapping-XCO_(2))using the XCO_(2) retrievals from GOSAT and OCO-2 during the period from April 2009 to December 2020 based on a geostatistical approach that fills those data *** dataset covers a geographic range from 56°S to 65°N and 169°W to 180°E for a 1°grid interval in space and 3-day time *** uncer-tainties of the mapped XCO_(2) values are generally less than 1.5 parts per million(ppm).The spatiotemporal characteristics of global XCO_(2) that are revealed by the Mapping-XCO_(2) are similar to the model data obtained from *** to the ground observa-tions,the overall standard bias is 1.13 *** results indicate that this long-term Mapping-XCO_(2) dataset can be used to investigate the spatiotemporal variations of global atmospheric XCO_(2) and can support studies related to the carbon cycle and anthropogenic CO_(2) *** dataset is available at http://***/10.7910/DVN/4WDTD8 and https://***/en/detail?dataSetId=c2c3111b421043fc8d9b163c39e6f56e.

关键词： Global land mapping atmospheric CO_(2)column concentration satellite observation GOSAT OCO-2