检索结果-南通市图书馆

Sm-Nd and zircon SHRIMP U-Pb dating of Huilanshan mafic granulite in the Dabie Mountains and its zircon trace element geochemistry

在线全文

学校读者我要写书评

暂无评论

science china earth sciences 2005年第12期48卷 2081-2091页

作者： HOU Zhenhui1, li Shuguang1, chen Nengsong2, li Qiuli1 & liU Xiaoming3 1. school of earth and space sciences, university of science and Technology of china, hefei 230026, china 2. The Key Laboratory of Continental Dynamics of the Ministry of Education, Northwest university, Xi’an 710069, china 3. Faculty of earth sciences, china university of Geosciences, Wuhan 430074, china 1. school of earth and space sciences University of Science and Technology of China 230026 Hefei China 2. The Key Laboratory of Continental Dynamics of the Ministry of Education Northwest University 710069 Xi’an China 3. Faculty of earth sciences China University of Geosciences 430074 Wuhan China

The mafic granulites from Huilanshan are outcropped on the center of the Luotian dome in the northern Dabie Mountains. The Sm-Nd isochron defined by granulite-facies meta-morphic minerals (garnet + clinopyroxene + hypersthene) yields an age of 136 ± 18 Ma indicating the early Cretaceous granulite-facies metamorphism. The cathodoluminescence (CL) images of zircons from the granulite show clearly core-mantle-rim structures. The zircon cores are charac-terized by typical oscillatory zoning and highly HREE enriched patterns, which suggests their magma origin. Some zircon cores among them with little Pb loss give SHRIMP U-Pb ages rang-ing from 753 to 780 Ma, which suggests that the protolith of Huilanshan granulite is Neopro-terozoic mafic rocks. The zircon mantles usually cut across the oscillatory zone of the zircon cores have 3―10 times lower REE, Th, U, Y, Nb and Ta contents than the igneous zircon cores but have high common Pb contents. These characteristics suggest that they were formed by hydrothermal alteration of the igneous zircons. The part of zircon mantles with little Pb loss give a similar SHRIMP U-Pb age (716―780 Ma) to the igneous zircon cores, which implies that the hydrothermal events occurred closely to the magmatic emplacement. In view of the strong early Cretaceous magmatism in the Luotian dome, consequently, the Huilanshan mafic granulite was formed by heating of the Neoproterozoic mafic rocks in mid-low crust, which caused the granu-lite-facies metamorphism underneath the Dabie Mountains. The similarity between the granulite metamorphic age (136 ± 18 Ma) defined by Sm-Nd isochron and K-Ar age of 123―127 Ma given by amphible from the gneiss in Luotian dome suggests a rapid uplifting of the Luotian dome, which may result in further exhumation of the ultrahigh pressure metamorphic rocks in the Dabie Mountains.

关键词： Dabie orogen, granulite, zircon U-Pb ages, Sm-Nd age.

A guidance strategy for rendezvous and docking to the space station in the earth-Moon NRHO orbit

在线全文

学校读者我要写书评

暂无评论

中国空间科学技术（中英文） 2024年第4期44卷 29-39页

作者： XIE Yongchun chen Changqing li Xiangyu li Zhenyu Beijing Institute of Control Engineering Beijing 100094China school of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

With the development of space technology,it is possible to build a space station in earth-Moon space as a transit for earth-Moon round-trip and entering in the deep *** and docking is one of the key technologies for building an earth-Moon space station.A guidance strategy for rendezvous and docking from the earth orbit to the space station in the earth-Moon NRHO orbit is proposed in this paper,which is suitable for engineering ***,the rendezvous and docking process is divided into three sections,i.e.,the large-range orbit transfer section,far-range guidance section,and close-range approaching *** suitable terminal of large-range orbit transfer is selected according to the eigenvalue of NRHO orbit state transition *** two-impulse guidance method based on the relative motion equation in the three-body problem is adopted for the far-range guidance *** impulse time and amplitude are solved with the optimization *** linear constant three-body relative motion equation is proposed for the close-range approaching section,and the rendezvous and docking is completed by a two-stage linear ***,a simulation analysis is carried out,and the simulation results show that the adopted dynamics equations and the designed guidance law are effective,and the three flight phases are naturally connected to accomplish the rendezvous and docking mission from the earth orbit to the space station on the earth-Moon NRHO.

关键词： earth-Moon space station rendezvous and docking NRHO orbit relative motion guidance strategy

Zircon Zr isotope fractionation during crustal anatexis

在线全文

学校读者我要写书评

暂无评论

science china earth sciences 2024年第8期67卷 2495-2506页

作者： Erlin ZHU Qiongxia XIA Zhaoya li Renxu chen James VAN ORMAN school of earth and space sciences University of Science and Technology of ChinaHefei 230026China State Key Laboratory of lithospheric and Environmental Coevolution Hefei 230026China Frontiers science Center for Planetary Exploration and Emerging Technologies University of Science and Technology of ChinaHefei 230026China Department of earth Environmental and Planetary SciencesCase Western Reserve UniversityCleveland OH 44106USA

Zirconium is one of high field strength elements but its isotope behavior during geochemical processes is still uncertain because of the limited *** Zr isotopes in magmatic rocks are often used to trace the evolution of magmas through fractional crystallization,it is intriguing how highly heterogeneous Zr isotopes were produced by the growth of zircon during crustal *** address this issue by in-situ zircon Zr isotope analyses of migmatites from two high-temperature metamorphic terranes in the South Lhasa zone and the North Dabie zone,respectively,in *** results show highly variable δ^(94)Zr values from-0.30‰ to +0.81‰ and from-0.58‰ to +0.49‰,*** addition to the relict zircon of magmatic origin,two types of newly-grown zircons were identified in terms of their occurrences,trace elements and δ^(94)Zr *** peritectic zircon,mainly occurring in the in-situ leucosomes,exhibits the highest Nb-Ta-Hf-U contents and variably higher δ^(94)Zr values than those of the relict *** anatectic zircon,mainly occurring in the leucocratic veins,shows higher Nb-Ta-Hf-U contents than and similar δ^(94)Zr values to those of the relict *** calculations demonstrate that the variable Zr isotope compositions of newly-grown zircons would result from decoupled release of Zr from zircon and non-zircon *** Zr supply of the peritectic zircon is mainly derived from the decomposition of Zr-bearing minerals in the in-situ anatectic melt(the non-zircon effect),whereas the Zr supply of the anatectic zircon is mainly from the dissolution of pre-existing zircons in the evolved melt(the zircon effect).The significant Zr isotope variations in the migmatites well illustrate the generation,migration and accumulation of the anatectic melts during the partial ***,Zr isotopes can be used as a powerful means for distinguishing between the peritectic and anatectic zircons during crustal anatexis.

关键词： Zr isotopes Zircon effect Non-zircon effect Migmatite Crustal anatexis

Field-aligned Currents in Io’s Plasma Wake

在线全文

学校读者我要写书评

暂无评论

Field-aligned Currents in Io’s Plasma Wake

Formation and growth of nanophase iron particles on the surface of Mercury revealed by experimental study

第十二届全国日地空间物理学术讨论会

作者： chuxin chen school of earth and space sciences,university of science and Technology of china,hefei 230026

＜正＞In Io’s reference frame,the downstream distribution of various physical quantities in Io’s plasma wake can be regarded as unchangeable with respect to time.A magnetic flux tube in a specific position in the wake can be related to a state of its evolution after been perturbed by *** the investigation of the wake can be transferred to the study of an Io-perturbed flux tube in the Jovian corotational frame.A

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Acta Geochimica 2024年第4期43卷 774-784页

作者： Ronghua Pang Yang li chen li Pengfei Zhang Zhuang Guo Sizhe Zhao Han Yu li Wang chenxi Zhu Shuangyu Wang Kairui Tai Qinwei Zhang Yuanyun Wen Rui li Center for Lunar and Planetary sciences Institute of GeochemistryChinese Academy of SciencesGuiyangChina university of Chinese Academy of sciences BeijingChina Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefeiChina Institute of Remote Sensing and Geographical Information System School of Earth and Space SciencesPeking UniversityBeijingChina State Key Laboratory of Lunar and Planetary sciences Macao University of Science and TechnologyMacaoChina Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunmingChina State Key Laboratory of High Performance Ceramics and Superfi ne Microstructures Shanghai Institute of CeramicsChinese Academy of SciencesShanghaiChina Laboratory for space Environment and Physical sciences Harbin Institute of TechnologyHarbinChina Research Center for Planetary science College of Earth ScienceChengdu University of TechnologyChengduChina Key Laboratory of Planetary sciences Purple Mountain ObservatoryChinese Academy of SciencesNanjingChina

space weathering is a primary factor in altering the composition and spectral characteristics of surface materials on airless ***,current research on space weathering focuses mainly on the Moon and certain types of *** particular,the impacts of meteoroids and micrometeoroids,radiation from solar wind/solar flares/cosmic rays,and thermal fatigue due to temperature variations are being *** weathering produces various transformation products such as melted glass,amorphous layers,iron particles,vesicles,and solar wind *** in turn lead to soil maturation,changes in visible and near-infrared reflectance spectra(weakening of characteristic absorption peaks,decreased reflectance,increased near-infrared slope),and alterations in magnetism(related to small iron particles),collectively termed the“lunar model”of space weathering *** to the Moon and asteroids,Mercury has unique spatial environmental characteristics,including more intense meteoroid impacts and solar thermal radiation,as well as a weaker particle radiation environment due to the global distribution of its magnetic ***,the lunar model of space weathering may not apply to *** studies have extensively explored the eff ects of micrometeoroid ***,this work focuses on the eff ects of solar-wind particle radiation in global magnetic-field distribution and on the weathering transformation of surface materials on Mercury under prolonged intense solar *** the utilization of highvalence state,heavy ion implantation,and vacuum heating simulation experiments,this paper primarily investigates the weathering transformation characteristics of the major mineral components such as anorthite,pyroxene,and olivine on Mercury’s surface and compares them to the weathering transformation model of the *** experimental results indicate that ion implantation at room temperature is insufficient to generate np-Fe^(0)directly but

关键词： Mercury space weathering Np-Fe^(0) Solar thermal radiation Solar wind

Evaluation on cutting performance of novel PDC cutter for pipe jacking machine

在线全文

学校读者我要写书评

暂无评论

Underground space 2024年第1期14卷 34-52页

作者： Long-Chuan Deng Yi-Xiang Yuan Xiao-Zhao li Qian-Wei Zhuang Chi Zhang Yi-Wei chen school of earth sciences and Engineering Nanjing UniversityNanjingJiangsu 210023China Shanghai Tunnel Engineering Co.Ltd. Shanghai 200232China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhouJiangsu 221116China school of Mechanics and Engineering science Shanghai UniversityShanghai 200444China

It is inevitable to cut reinforced concrete(RC)appeared in cross passage of city metro by cutting tools when constructing in densely populated *** previous cutters employed to cut RC are insufficient and easily damaged,so a new polycrystalline diamond compact(PDC)cutter is used to solve this *** on the theoretical analysis of cutting mechanism,both circular and tapered PDC cutters with cutting edge angle of 90and negative front rack angle of 10are used to cut *** peeling and breaking patterns of cutting concrete are proposed,the nodular and grainy chips are the preferred modes in cutting steel *** LS-DYNA is employed to investigate the cutting performance in *** simulation results show that the average and peak cutting forces increase with the growth of penetration depth,cutting speed,and roundness,and subsequently the recommended penetration depth less than 1.2 mm is obtained to cut RC due to the existence of steel ***,the linear cutting platform is adopted to investigate the force ability and damage state of PDC *** is concluded that the cutting force increases abruptly and fluctuates heavily when cutting the coarse *** patterns occurred in both numerical and experimental results are generally ***,the steel bar is pulled out and the PDC cutter is damaged at the penetration depth of 0.8 mm,while a good cut occurs at the penetration depth of 0.3 *** tapered PDC cutter with a relatively low cutting force is prone to be broken compared with circular PDC *** is suggested that the circular PDC cutter at the penetration depth of 0.3 mm should be used to cut RC in practical engineering.

关键词： PDC cutter RC Pipe jacking machine linear cutting tests Damage and wear LS-DYNA

Global convergence in terrestrial gross primary production response to atmospheric vapor pressure deficit

维普期刊数据库评论

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(life sciences) 2024年第9期67卷 2016-2025页

作者： Chao Huang Jingfeng Huang Jingfeng Xiao Xing li Hong SHe Yu liang Fusheng chen Hanqin Tian Key Laboratory of National Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of ForestryJiangxi Agricultural UniversityNanchang 330045China CAS Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China Institute of Applied Remote Sensing&Information Technology College of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China Key Laboratory of Agricultural Remote Sensing and Information Systems Zhejiang ProvinceZhejiang UniversityHangzhou 310058China earth Systems Research Center Institute for the Study of EarthOceansand SpaceUniversity of New HampshireDurham NH 03824USA Research Institute of Agriculture and life sciences Seoul National UniversitySeoul 08826South Korea school of Natural Resources University of Missouri203 ABNR BuildingColumbiaMO 65211USA Schiller Institute for Integrated science and Society Department of Earth and Environmental SciencesBoston CollegeChestnut HillMA 02467USA

Atmospheric vapor pressure deficit(VPD)increases with climate warming and may limit plant ***,gross primary production(GPP)responses to VPD remain a mystery,offering a significant source of uncertainty in the estimation of global terrestrial ecosystems carbon *** this study,in-situ measurements,satellite-derived data,and earth System Models(ESMs)simulations were analysed to show that the GPP of most ecosystems has a similar threshold in response to VPD:first increasing and then *** VPD exceeds these thresholds,atmospheric drought stress reduces soil moisture and stomatal conductance,thereby decreasing the productivity of terrestrial *** ESMs underscore CO_(2) fertilization effects but predict significant GPP decline in low-latitude ecosystems when VPD exceeds the *** results emphasize the impacts of climate warming on VPD and propose limitations to future ecosystems productivity caused by increased atmospheric water *** VPD,soil moisture,and canopy conductance interactions into ESMs enhances the prediction of terrestrial ecosystem responses to climate change.

关键词： atmospheric water demands soil moisture stomatal conductance photosynthesis climate warming

Reconciled estimation of Antarctic ice sheet mass balance and contribution to global sea level change from 1996 to 2021

在线全文

学校读者我要写书评

暂无评论

science china earth sciences 2024年第11期67卷 3562-3578页

作者： Rongxing li Guojun li Gang HAI Huan XIE Yuan chenG Wei chen Xiangbin CUI Minghu DING Chunchun GAO Tong HAO Changqing KE Chuanjin li Jin li Yan liU Jiangjun RAN Jiawen REN Qiang SHEN Yunzhong SHEN Hongling SHI Songyun WANG Zemin WANG Jingang ZHAN Baojun ZHANG Min ZHONG Chunxia ZHOU Center for Spatial Information science and Sustainable Development Applications Tongji University College of Surveying and Geo-informatics Tongji University Institute for the Conservation of Cultural Heritage School of Cultural Heritage and Information Management Shanghai University College of Resource Environment and Tourism Hubei University of Arts and Science Polar Research Institute of china State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences College of Geodesy and Geomatics Shandong University of Science and Technology school of Geography and Ocean science Nanjing University Shanghai Astronomical Observatory Chinese Academy of Sciences State Key Laboratory of Remote Sensing science Faculty of Geographical Science Beijing Normal University Department of earth and space sciences Southern University of Science and Technology State Key Laboratory of Cryospheric science Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences State Key Laboratory of Geodesy and earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of Sciences Center for space Research University of Texas at Austin Chinese Antarctic Center of Surveying and Mapping Wuhan University school of Geospatial Engineering and science Sun Yat-sen University

The Antarctic Ice Sheet（AIS） has been losing ice mass and contributing to global sea level rise（GSLR）. Given its mass that is enough to cause ～58 m of GSLR, accurate estimation of mass balance trend is critical for AIS mass loss monitoring and sea level rise forecasting. Here, we present an improved approach to reconciled solutions of mass balance in AIS and its regions from multiple contributing solutions using the input-out, altimetric, and gravimetric methods. In comparison to previous methods, such as IMBIE 2018, this approach utilizes an adaptive data aggregation window to handle the heterogeneity of the contributing solutions, including the number of solutions, temporal distributions, uncertainties, and estimation techniques. We improved the regression-based method by using a two-step procedure that establishes ensembled solutions within each method（input-output, altimetry, or gravimetry） and then estimates the method-independent reconciled solutions. For the first time, 16contributing solutions from 8 Chinese institutions are used to estimate the reconciled mass balance of AIS and its regions from1996 to 2021. Our results show that AIS has lost a total ice mass of ～3213±253 Gt during the period, an equivalent of～8.9±0.7 mm of GSLR. There is a sustained mass loss acceleration since 2006, from 88.1±3.6 Gt yr-1during 1996–2005 to 130.7 ±8.4 Gt yr-1during 2006–2013 and further to 157.0±9.0 Gt yr-1during 2014–2021. The mass loss signal in the West Antarctica and Antarctic Peninsula is dominant and clearly presented in the reconciled estimation and contributing solutions, regardless of estimation methods used and fluctuation of surface mass balance. Uncertainty and challenges remain in mass balance estimation in East Antarctica. This reconciled estimation approach can be extended and applied for improved mass balance estimation in the Greenland Ice Sheet and mountain glacier regions.

关键词： Antarctic Ice Sheet Ice mass loss acceleration Sea level rise Reconciled estimation

space advanced technology demonstration satellite

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Technological sciences) 2024年第1期67卷 240-258页

作者： ZHANG XiaoFeng chen Wen ZHU Xiaocheng MENG Na HE JunWang BI XingZi ZHANG YongHe SHI Qi li Fei liU Rui FENG ZhengGong liU liu li JinSong WU Haichen XU DongXiao li TaiJie HUANG JiangJiang liU Shuo li TianTong YU XianSheng GAO Yang ZHOU Heng BAN HanYu ZHANG Yanli ZHANG YueTing YANG YingQuan HE Tao DUAN Xuliang chen Xin WANG YaMin SUN AnTai ZHANG KuoXiang SUN Ying WANG YaoBin FAN chengcheng XIONG Shaolin li XinQiao WEN XiangYang liNG ZhiXing SUN XiaoJin ZHANG chen BAI XianYong WANG ZhanShan DENG YuanYong TIAN Hui YANG JianFeng XUE HongBo SANG Peng liU JinGuo ZHENG HuiLong ZHU Xiang HE JianWu li Hui XU LuXiang XU ShuYan chen WenWu liU ZhenDong WANG Zhaoli MAO XiangLong GAO Rong li ZongXuan DING GuoPeng WANG XinYu DOU RunJiang WENG LuBin LUO Hao WANG YaPing liANG XianFeng FANG ZiRuo Innovation Academy for Microsatellites Chinese Academy of SciencesShanghai 201203China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China National Astronomical Observatory of china Beijing 100101China Shanghai Institute of Technical Physics Chinese Academy of SciencesShanghai 200083China Institute of Precision Optical Engineering School of Physics Science and EngineeringTongji UniversityShanghai 200092China school of earth and space sciences Peking UniversityBeijing 100871China Xi’an Institute of Optics and Precision Mechanics Chinese Academy of SciencesXi’an 710119China National space science Center Chinese Academy of SciencesBeijing 100190China Shenyang Institute of Automation Chinese Academy of SciencesShenyang 110016China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China Shanghai Institute of Organic Chemistry Chinese Academy of SciencesShanghai 200032China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China Nanyang Technological university Singapore 569830Singapore Dalian Institute of Chemical Physics Chinese Academy of SciencesDalian 116023China Technical Institute of Physics and Chemistry Chinese Academy of SciencesBeijing 100049China Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Institute of Semiconductors Chinese Academy of SciencesBeijing 100083China Institute of Automation Chinese Academy of SciencesBeijing 100190China school of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310058China

The space Advanced Technology demonstration satellite(SATech-01),a mission for low-cost space science and new technology experiments,organized by Chinese Academy of sciences(CAS),was successfully launched into a Sun-synchronous orbit at an altitude of~500 km on July 27,2022,from the Jiuquan Satellite Launch *** as an experimental platform for space science exploration and the demonstration of advanced common technologies in orbit,SATech-01 is equipped with 16 experimental payloads,including the solar upper transition region imager(SUTRI),the lobster eye imager for astronomy(LEIA),the high energy burst searcher(HEBS),and a High Precision Magnetic Field Measurement System based on a CPT Magnetometer(CPT).It also incorporates an imager with freeform optics,an integrated thermal imaging sensor,and a multi-functional integrated imager,*** paper provides an overview of SATech-01,including a technical description of the satellite and its scientific payloads,along with their on-orbit performance.

关键词： SATech-01 spacecraft design scientific instruments on-orbit performance