检索结果-南通市图书馆

Subsurface multi-physical characterization of mountain excavation and city construction in loess plateau with a fiber-optic sensing system

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical engineering 2024年第8期16卷 2935-2946页

作者： Jie Liu Bin Shi Kai Gu Meng-Ya Sun Jun-Cheng Yao He-Ming Han School of earth sciences and engineering Nanjing UniversityNanjingJiangsu210023China Frontiers Science Center for Critical earth Material Cycling Nanjing UniversityNanjing210023China School of earth sciences and engineering Hohai UniversityNanjing210098China

Mountain excavation and city construction(MECC)projects being launched in the Loess Plateau in China involve the creation of large-scale artificial *** the subsurface evolution characteristics of the artificial land is essential,yet ***,we use an improved fiber-optic monitoring system for its subsurface multi-physical *** system enables us to gather spatiotemporal distribution of various parameters,including strata deformation,temperature,and ***’an New District was selected as a case study to conduct refined in-situ monitoring through a 77 m-deep borehole and a 30 m-long *** reveal that the ground settlement involves both the deformation of the filling loess and the underlying intact ***,the filling loess exhibits a stronger creep capability compared to underlying intact *** deformation along the profile is unevenly distributed,with a positive correlation with soil *** accumulation has been observed at the interface between the filling loess and the underlying intact loess,leading to a significant ***,the temperature and moisture in the filling loess have reached a new equilibrium state,with their depths influenced by atmospheric conditions measuring at 31 m and 26 m,*** refined investigation allows us to identify critical layers that matter the sustainable development of newly created urban areas,and provide improved insights into the evolution mechanisms of land creation.

关键词： Mountain excavation and city construction Fiber-optic monitoring Multi-physical characterization Compacted loess

Effect of Er_(30)Cu_(70) on microstructure and properties of sintered Nd-Fe-B by grain boundary reconstruction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare earths 2024年第2期42卷 345-353,I0004页

作者： Kai Wang Yongtao Dai Jianqiu Deng Jiang Wang Huaiying Zhou Qingrong Yao Weichao Huang Guangxi Key Laboratory of Information Materials Schoolof Materials Science and EngineeringGuilin University of Electronic TechnologyGuilin54004China China Rare Metals and Rare earth(Guangxi)Jinyuan New Materials Co Ltd.Hezhou542603China

Usually it is generally believed that the Er element forms the Er_(2)Fe_(14)B phase,which will seriously deteriorate the magnetic ***,here we report the balance of corrosion resistance and coercivity in Nd-Fe-B sintered magnets through using simple Er_(30)Cu_(70) additive whose price is much lower than Dy and *** reasonably controlling Er_(30)Cu_(70) addition,the corrosion resistance is improved at the minimum limit of reducing the magnetic *** studying the influence mechanism of Er element,it is found that the main effect of Er elements is to replace the Nd elements at the edge of the main phase grains to form a(Er,Nd)_(2)Fe_(14)B shell with low H_(A),resulting in the reduction of magnetic *** improvement of corrosion resistance mainly comes from the more stable Cu element introduced at the grain *** the same time,the target magnets also show different advantages under different heat treatment *** findings may spur progress towards developing the lowcost permanent magnets that rival the commercial Nd-Fe-B counterpart.

关键词： Er_(30)Cu_(70)alloy Grain boundary reconstruction Magnetic properties Corrosion resistance Heat treatment Rare earths

Remnants and fragments of the subducted paleo-Pacific plate:Constraints from geochemistry and geophysics

在线全文

学校读者我要写书评

暂无评论

Science China earth sciences 2024年第10期67卷 3041-3061页

作者： Xisheng XU Zhouchuan HUANG Dingsheng JIANG Gang ZENG Li-Qun DAI State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023China School of earth and Space sciences University of Science and Technology of ChinaHefei 230026China

The subduction and rollback of the paleo-Pacific plate during Mesozoic time was the key engine for the evolution of the continental margin in eastern China. It led to lateral accretion of continental crust in Northeast China, lithospheric destruction beneath the North China Craton, and the generation of huge volumes of felsic magmatic rocks in South China. This had a profound influence on deep material cycles and the evolution of epigenetic environmental systems along the continental margin of East Asia. To fully understand the transformation of the dynamic mechanism during the subduction and rollback of the paleoPacific plate, we have attempted to trace the remnants and fragments of the subducted paleo-Pacific plate at great depths. Such remnants in both temporal and spatial dimensions can be tracked by using geochemical and geophysical approaches. Studies of the trace elements, Mg-Zn isotopes and Os-Nd-Hf-Pb-O isotopes in continental basalts from eastern China reveal a significant number of the remnants of subduction of the paleo-Pacific plate, and the initial subduction can be traced back to the Early Jurassic. Large-scale geophysical imaging unveils a multitude of high-velocity anomalies in the lower mantle of East ***, many high-velocity bodies, aptly referred to as “slab graveyards”, are nestled at the base of the lower mantle. Numerous isolated high-velocity anomalies are also present in the upper part of the lower mantle, creating conduits for the descent of the subducted slabs into the lower mantle. However, a resolution of the remnants for the subducted slabs within the lower mantle are quite low. Consequently, their impact on the lower mantle's dynamics is yet to be thoroughly investigated. Finally, the presently observed big mantle wedge(BMW) in East Asia has developed through subduction of the Pacific plate in the ***, following the rollback of the paleo-Pacific plate(began at ~145 Ma), a Cretaceous BMW system would also form above

关键词： Paleo-Pacific plate Big mantle wedge Late Mesozoic Remnants and fragments Geochemistry Geophysics

AHFO-based soil water content sensing technology considering soil-sensor thermal contact resistance

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical engineering 2024年第7期16卷 2715-2731页

作者： Mengya Sun Peng Wu Bin Shi Jin Liu Jie Liu Juncheng Yao Yipin Lu Yunqiang Wang Xiaoyan Li School of earth sciences and engineering Hohai UniversityNanjing210098China School of earth sciences and engineering Nanjing UniversityNanjing210023China Department of Architecture and Civil engineering City University of Hong Kong999077Hong KongChina State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an710061China

The actively heated fiber-optic(AHFO)technology has become emerged as a research focus due to its advantages of distributed,real-time measurement and good *** attributes have led to the gradual application of AHFO technology to the water content measurement of in situ ***,all existing in situ applications of AHFO technology fail to consider the effect of soilesensor contact quality on water content measurements,limiting potential for the wider application of AHFO *** address this issue,the authors propose a method for determining the soilesensor thermal contact resistance based on the principle of an infinite cylindrical heat *** is then used to establish an AHFO water content measurement technology that considers the thermal contact *** reliability and validity of the new measurement technology are explored through a laboratory test and a field case study,and the spatial-temporal evolution of the soil water content in the case is *** results demonstrate that method for determining the soilesensor thermal contact resistance is highly effective and applicable to all types of *** method requires only the moisture content,dry density,and thermal response of the in situ soil to be *** the field case,the measurement error of soil water content between the AHFO method,which takes into account the thermal contact resistance,and the neutron scattering method is only *** water content of in situ soil exhibits a seasonal variation,with an increase in spring and autumn and a decrease in summer and ***,the response of shallow soils to precipitation and evaporation is *** findings contribute to the enhancement of the accuracy of the AHFO technology in the measurement of the water content of in situ soils,thereby facilitating the dissemination and utilization of this technology.

关键词： Soil water content Actively heated fiber-optic(AHFO) technology Soilesensor thermal contact resistance Reliability In situ application

Carboniferous integrative stratigraphy,biotas,and paleogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

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 earth sciences 2024年第4期67卷 1071-1106页

作者： Keyi HU Xiangdong WANG Wenqi WANG Yingfan SONG Xunyan YE Lu LI Yukun SHI Sunrong YANG Ying LI State Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material CyclingNanjing UniversityNanjing 210023China

During the Carboniferous Period,the Qinghai-Tibetan Plateau and its surrounding areas were located in quite different paleogeographic positions with various sedimentary and biological *** is important to systematically compile and summarize the Carboniferous strata and biotas of the Qinghai-Tibetan Plateau and its surrounding areas,to establish an integrated stratigraphic framework for correlation,and to reconstruct the paleogeography for correctly understanding the breakup of the Gondwana Continent and the evolution of the Paleo-Tethys Ocean in the Late *** Carboniferous of the Qinghai-Tibetan Plateau and its surrounding areas can be subdivided into the Gondwanan,Cimmerian,and Tethyan *** Gondwanan-type Carboniferous are distributed in the North Himalayan,Kangmar-Lhunze,and Zanda-Zumba regions of the South Tibet Subprovince and northern India-Pakistan Area,where only the Mississippian is developed and the biota is of Gondwanan *** Cimmerian-type Carboniferous,which are found in the Baoshan,Tengchong,Coqen-Xainza,LhasaZayu,Nagqu-Biru,and South Qiangtang regions,as well as Shan-Thai and South Afghanistan-Pamir areas,also represent only the Mississippian strata,but their biota is characterized by mixed characters of European,South China,Australian,and North American *** Tethyan-type Carboniferous are distributed in the Tanggula Mountains,Hoh Xil-Bayanhar,ChamdoHengduanshan,Tiekelike,West Kunlun,Karakorum,East Kunlun-Central Qinling,and Qilian regions,where the Carboniferous succession is well developed,and the biota is of warm-water Tethyan *** biostratigraphical correlation of the Gondwanan-type and Cimmerian-type Carboniferous is based mainly on conodonts and additionally on brachiopods and rugose *** Mississippian of the Tethyan-type Carboniferous is correlated mainly by using rugose corals and brachiopods,whereas in the Pennsylvanian foraminifera(fusuline)and conodonts are regarded as primary fossil groups,subord

关键词： Qinghai-Tibetan Plateau Carboniferous Lithostratigraphy Biota Stratigraphic correlation

Unraveling the Cenozoic carbon cycle by reconstructing carbonate compensation depth(CCD)

在线全文

学校读者我要写书评

暂无评论

Science China earth sciences 2024年第6期67卷 1743-1758页

作者： Kaixun XIAO Xiumian HU Jingxin JIANG Jiahao WANG State Key Laboratory of Mineral Deposit Research School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023China

The Carbonate Compensation Depth(CCD)refers to the depth within the ocean where the production and dissolution rates of carbonates reach equilibrium,widely likened to the oceanic calcareous‘snowline’.The reconstruction of deep-time CCD has significant implications for understanding ocean circulation,seawater chemical conditions,sediment distribution,and the surface carbon *** paper critically reviews the methods for CCD reconstruction,summarizes the driving mechanisms of the Cenozoic CCD evolution and its association with the carbon cycle,and offers insights into future directions for CCD *** reconstruction has evolved over the past half century from early qualitative to quantitative *** methodological improvements have markedly improved the accuracy and resolution of *** studies have indicated a general trend of the CCD deepening across major ocean basins since the Cenozoic,interspersed with a minor shallowing phase during the *** variations in the CCD are primarily influenced by factors such as ocean productivity,weathering,and shelf-basin *** climate events such as the Paleocene-Eocene Thermal Maximum,the CCD exhibits pulselike *** research should focus on precision and quantification while integrating model simulations to further explore the correlations and response mechanisms between the CCD and the paleoclimate as well as the carbon cycle.

关键词： Carbonate Compensation Depth Cenozoic Carbon cycle Paleoclimate Paleoceanography

Global weirding at mass extinction horizons

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第1期11卷 10-12页

作者： Gregory J.Retallack Department of earth sciences University of Oregon

A strong motivation for studying mass extinctions is understanding how current climatic and biodiversity crises will affect creatures living on land such as ourselves. Perhaps the question is: how bad can it get? In that case, terrestrial Permian-Triassic mass extinctions are an irresistible worst-case scenario [1].

关键词：

Coupled DEM-FDM analyses of the effects of falling rock’s shape and impact angle on response of granular cushion and rock shed

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical engineering 2024年第8期16卷 3353-3364页

作者： Jingyu Xue Chen Cao Jianhua Yan Yaopeng Ji Jianping Chen College of Construction engineering Jilin UniversityChangchun130026China School of earth sciences and engineering Hohai UniversityNanjing210098China

Rock shed is an effective protection measure against *** investigate the influences of falling rock’s shape and impact angle on the impact effect of the cushioned rock shed,a modeling approach for a rock shed with a cushion layer using *** granular cushion is modeled as an aggregate of discrete non-cohesion particles,while the concrete plate and the beam are modeled as *** falling rock with different sphericities and impact angles is modeled as a rigid *** numerical model is validated by comparing the simulation results with experimental and numerical results from previous *** model is applied to analyze the effects of rock shape and impact angle on the dynamic interaction effects between falling rock and cushioned rock shed,including the impact force,transmitted bottom force,penetration depth,and plate *** numerical results show that the variation in the falling rock’s shape has different effects on the falling rock with different impact *** findings could support rock shed design by revealing the limitations of the assumptions in the past research,which may result in unsafe rock sheds for some rockfall cases.

关键词： Rockfall Coupled DEM-FDM analysis Rock’s shape Impact angle Granular cushion Rock shed

Interfacial Oxygen Octahedral Coupling-Driven Robust Ferroelectricity in Epitaxial Na_(0.5)Bi_(0.5)TiO_(3)Thin Films

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research 2024年第2期2023卷 149-157页

作者： Haojie Han Qinghua Zhang Wei Li Yiqun Liu Jiasheng Guo Yue Wang Qian Li Lin Gu Ce-Wen Nan Jing Ma State Key Laboratory of New Ceramics and Fine Processing Schoolof Materials Science and EngineeringTsinghua UniversityBeijing 100084China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

The oxygen octahedral rotation(OOR)forms fundamental atomic distortions and symmetries in perovskite oxides and definitely determines their properties and ***,epitaxial strain and interfacial structural coupling engineering have been developed to modulate the OOR patterns and explore novel properties,but it is difficult to distinguish the 2 ***,different symmetries are induced in Na_(0.5)Bi_(0.5)TiO_(3)(NBT)epitaxial films by interfacial oxygen octahedral coupling rather than epitaxial *** NBT film grown on the Nb:SrTiO_(3)substrate exhibits a paraelectric tetragonal phase,while with La_(0.5)Sr_(0.5)MnO_(3)as a buffer layer,a monoclinic phase and robust ferroelectricity are obtained,with a remanent polarization of 42μC cm^(-2)and a breakdown strength of 7.89 MV cm^(-1),which are the highest record among NBT-based ***,the interfacial oxygen octahedral coupling effect is demonstrated to propagate to the entire thickness of the film,suggesting an intriguing long-range *** work provides a deep insight into understanding the structure modulation in perovskite heterostructures and an important avenue for achieving unique functionalities.

关键词： effect. interfacial coupling