检索结果-南通市图书馆

Microstructural evolution and energetic characteristics of TiZrHfTa_(0.7)W_(0.3)high-entropy alloy under high strain rates and its application in high-velocity penetration

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 Materials Science & Technology 2023年第1期132卷 144-153页

作者： Weiqi Tang Kun Zhang tianyu chen Qiu Wang Bingchen Wei Key Laboratory of Microgravity(National Microgravity Laboratory) Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Energetic structural materials(ESMs)integrated a high energy density and rapid energy release with the ability to serve as structural ***,a novel triple-phase TiZrHfTa_(0.7)W_(0.3)high-entropy alloy(HEA)was fabricated and investigated as a potential ESM.A hierarchical microstructure was obtained with a main metastable body-centered-cubic(BCC)matrix with distributed Ta-W-rich BCC precipitates of various sizes and interwoven hexagonal close-packed(HCP)lamellar *** compressive me-chanical properties were tested across a range of strain rates and demonstrated a brittle-to-ductile tran-sition as the strain rate increased while maintaining a high ultimate strength of approximately 2.5 *** was due to the phase transformation from metastable matrix BCC to HCP *** addition,during the dynamic deformation,metal combustion originating from the failure surface was ***,the composition of the fragments was studied,and the results indicated that the addition of tungsten promoted ***,the potential application of this HEA was evaluated by high-velocity penetration tests,and the results were compared to other typical structural materials for pene-trators and bullets.A comparison was conducted by assessing the geometries of the penetration channel employing two dimensionless parameters normalized by the projectile size,representing longitudinal and lateral damage,*** normalized depth of the TiZrHfTa_(0.7)W_(0.3)HEA projectile was comparable to those of the other investigated materials,but the normalized diameter was the largest,showing an excellent ability to deliver lateral damage.

关键词： Energetic structural materials High-entropy alloys Phase transformation Ballistic tests

Potassium isotopic signatures of modern offshore detrital sediments from different climatic regimes and the implications

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2期67卷 405-419页

作者： Jun MU tianyu chen Qian YU Shichao AN Jianfang chen Xuefa SHI Weiqiang LI State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing UniversityNanjing210023China Ministry of Education Key Laboratory for Coast and Island Development School of Geography and Ocean ScienceNanjing UniversityNanjing210023China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou310012China Key Laboratory of Marine Geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao266061China

Potassium isotopes are a novel tracer for continental *** K isotope studies on chemical weathering generally targeted weathering profiles under a particular climate region,yet the effects of chemical weathering on K isotopes under different climatic backgrounds remain ***,little is known about the K isotope signatures of modern unconsolidated detrital ***,we report K isotopic data of surficial seafloor sediments from continental shelves along the east coast of China(ECC),as well as those around the tropical Hainan island in the northern South China *** ECC sediments have a relatively narrow distribution ofδ^(41)K(with reference to NIST3141a)values,which range from(-0.40±0.01)‰to(-0.57±0.04)‰,with an average of(-0.51±0.09)‰.By contrast,δ^(41)K values of Hainan offshore sediments display a larger variation,ranging from(-0.28±0.07)‰to(-0.67±0.02)‰.Theδ^(41)K values of Hainan offshore sediments exhibit negative correlations with the chemical index of alteration(CIA),Al/K,Ti/K,and total iron(FeT),which underlines the control of chemical weathering on K isotopic signatures of detritus inputs into *** also measured Mg isotope compositions for the same samples;interestingly,the variability inδ^(26)Mg of the samples is small(~0.24‰)for all ECC and Hainan offshore sediments,andδ^(26)Mg values do not show clear correlations with indexes of chemical *** study demonstrates the link between K isotopic variability of detrital sediments and climatic conditions including rainfall intensity,which indicates that K isotopes of the detrital component of marine sediments could be applied to study Earth’s climate in deep ***δ^(41)K values of the offshore detrital sediments are significantly less variable than those of pelagic marine sediments,highlighting the importance of distinguishing the effects of diagenesis and neoformation of clay minerals from continental weathering in attempts to study deep-time climate-weathering

关键词： Potassium isotopes Magnesium isotopes Chemical weathering Detrital sediments Climatic regimes Mean annual precipitation

Limited Contribution of Preferential Dissolution to Radiogenic Uranium Isotope Disequilibrium Observed in Weathered Moraines

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2022年第1期33卷 57-66页

作者： Laifeng Li Laura FRobinson tianyu chen Zhewen Xu Jun chen Gaojun Li MOE Key Laboratory of Surficial Geochemistry Department of Earth and Planetary SciencesNanjing UniversityNanjing 210023China School of Geography and Ocean Science Nanjing UniversityNanjing 210023China School of Earth Sciences University of BristolBristol BS81RJUK Frontiers Science Center for Critical Earth Material Cycling Nanjing UniversityNanjing 210023China

Radiogenic uranium isotope disequilibrium(^(234)U/^(238)U) has been used to trace a variety of Earth surface processes,and is usually attributed to direct recoil of ^(234)Th and preferential dissolution of radioactively damaged lattices at the mineral ***,the relative contribution of these two mechanisms in the natural environment remains unresolved,making it hard to use the extent of disequilibrium to quantify processes such as *** study tests the contribution of preferential dissolution using well-characterized weathered moraines and river sediments from the southeastern Tibetan *** observations show that weathering of recent moraines where the contribution from direct recoil is negligible and is not associated with depletion of ^(234)U at the mineral *** suggests a limited role for preferential dissolution in this *** attribute this lack of preferential dissolution to a near-to-equilibrium dissolution at the weathering interfaces,with little development of etch pits associated with radioactively damaged energetic sites.

关键词： preferential dissolution uranium isotope disequilibrium Gongga Mountain comminution comminution age etch pits

Fast Protection Strategy for DC Transmission Lines of MMC-based MT-HVDC Grid

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electrical Engineering 2021年第2期7卷 83-92页

作者： Sihua Wang Lijun Zhou Tian Wang tianyu chen Yu Wang College of Automation&Electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070China Rail Transit Electrical Automation Engineering Laboratory of Gansu Province Lanzhou Jiaotong UniversityLanzhou 730070China

Multi-terminal high voltage DC(MT-HVDC)grid has broad application prospects in connecting different energy sources,asynchronous interconnection of power grids,remote load power supply,and other *** present,the key technologies that affect the development of MT-HVDC transmission system include swift fault identification and location in the DC line and its rapid *** fault monitoring relies on line communication,which cannot guarantee the rapidity and reliability of protection;moreover,it may even cause device damage.A fault identification scheme based on a single-terminal transient is presented in this *** scheme calculates the line inductance by using the rise rate of fault current at the initial stage of the fault,and determines the occurrence of the fault by comparing the observed line inductance with the set value,which lays a foundation for calculating the location of the fault point using distance protection.A simulation model on the PSCAD/EMTDC platform is built;the simulation example verifies that the proposed scheme can identify faults under dissimilar conditions while maintaining a low error level on the premise of no communication lines so as to meet the protection requirements of the MT-HVDC grid.

关键词： Multi-terminal high voltage DC(MT-HVDC)grid modular multilevel converter(MMC) DC circuit breaker(DCCB) bipolar short-circuit fault identification

Late Miocene Pods and Leaves of Albizzia (Leguminosae:Mimosoideae) from Yunnan,SW China and Their Phytogeographic Implications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2017年第4期91卷 1190-1199页

作者： LI Binke XIE Sanping ZHANG Sihang chen tianyu SHAO Yang School of Earth Sciences and Key Laboratory of Mineral Resources in Western China(Gansu Province) Lanzhou University State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PaleontologyCAS

Albizzia is a leguminous genus belonging to the subfamily Mimosoideae with approximately 150 modern species, widely distributed in the tropical and subtropical regions of Asia, Africa, Australia and America. Among them, 17 species are mainly distributed in southern and southwestern China. Abundant fossils of the subfamily Mimosoideae, including leaves, pods, flowers and wood, have been reported from the Cretaceous and Paleogene strata of the Northern Hemisphere. However, Neogene records of Mimosoideae are relatively scarce. In this study, fossil pods and leaves belonging to the genus Aibizzia from the Bangmai Formation of Yunnan, China were described. They were assigned to three species, including Albizzia scalpeUiformis Guo, Li and Xie Emended, Albizzia cf. kalkora （Roxb.） Prain and Albizzia sp. The occurrence of Albizzia fossils from Lincang not only gives important information on the Neogene plant diversity from Yunnan--a worldwide famous biological hotspot--but also provides additional evidence for its phytogeographic history.

关键词： Albizzia Mimosoideae morphology Late Miocene Lincang

CLIMATOLOGICAL ANALYSIS OF SEASONAL SNOW RESOURCES IN THE QILIAN MOUNTAINS

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 1991年第1期 59-77页

作者： chen Qian chen tianyu Lanzhou Institute of Arid Meteorology

Snow parameters retrieved from NOAA AVHRR data during October 1986--September 1988 are contrasted with data on daily snow depth,snow density and snow days attained from 26 weather stations in the Qilian Mountain region during the period 1951-88 for the purpose of correcting the retrieved snow *** distribution of high resolution climatological mean depth and frequency of snow cover have been *** snow storage,snowfall and snow-melting runoff of the river basins in this region are estimated.

关键词： snow resources satellite data Qilian Mountain region

Blinking CsPbBr_(3) perovskite nanocrystals for the nanoscopic imaging of electrospun nanofibers

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2021年第5期14卷 1397-1404页

作者： tianyu chen Mengna Huang Zhongju Ye Jianhao Hua Shen Lin Lin Wei Lehui Xiao State Key Laboratory of Medicinal Chemical Biology Tianjin Key Laboratory of Biosensing and Molecular RecognitionCollege of ChemistryNankai UniversityTianjin300071China Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research Ministry of EducationKey Laboratory of Phytochemical R&D of Hunan ProvinceCollege of Chemistry and Chemical EngineeringHunan Normal UniversityChangsha410081China

Blinking fluorophore perovskite nanocrystals (NCs) were employed to image the fine structure of the polystyrene (PS) electrospun fibers. The conditions of CsPbBr3 NCs embedded and dispersed into PS were investigated and optimized. The stochastic optical reconstruction microscopy is employed to visualize the fine structure of the resulted CsPbBr3@PS electrospun fibers at sub-diffraction limit. The determined resolution in the reconstructed nanoscopic image is around 25.5 nm, which is much narrower than that of conventional fluorescence image. The complex reticulation and multicompartment in bead sub-diffraction-limited structures of CsPbBr3@PS electrospun fibers were successfully mapped with the help of the stochastic blinking properties of CsPbBr3 NCs. This work demonstrated the potential applications of CsPbBr3 perovskite NCs in super-resolution fluorescence imaging to reconstruct the sub-diffraction-limited features of polymeric material.

关键词： CsPbBr_(3) perovskite nanocrystals polystyrene electrospun nanofiber super-resolution optical imaging

CO_2 emission and organic carbon burial in the Xinanjiang Reservoir

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2017年第3期36卷 465-468页

作者： Fushun Wang Baoli Wang Tao Zhou tianyu chen Jing Ma School of Environmental and Chemical Engineering Shanghai University Institute of Surface-Earth System Science Tianjin University

In order to understand the effect of river impoundment on carbon dynamics, a large reservoir in a subtropical area, the Xinanjiang Reservoir, was investigated in detail. CO_2 emissions from the water–air interface was studied, as was organic carbon burial in sediment. The results show a significant seasonal difference in CO_2 emissions. River impoundment led to the enhancement of aquatic photosynthesis, generating large amounts of authigenic organic carbon that was then buried in sediment.

关键词： The Xinanjiang Reservoir Carbon emission Sediment Carbon retention

Deep-sea coral evidence for dissolved mercury evolution in the deep North Pacifi c Ocean over the last 700 years

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2021年第5期39卷 1622-1633页

作者： Yang QU Kuidong XU Tao LI Maoyu WANG Huan ZHONG tianyu chen State Key Laboratory for Mineral Deposits Research School of EarthSciences and Engineering and Frontiers Science Center for Critical Earth Material CyclingNanjing UniversityNanjing 210023China Laboratory of Marine Organism Taxonomy and Phylogeny Institute ofOceanologyCenter for Ocean Mega-ScienceChinese Academy of SciencesQingdao 266071China State Key Laboratory of Pollution Control and Resources Reuse School ofthe EnvironmentNanjing UniversityNanjing 210023China Environmental and Life Sciences Program(EnLS) Trent UniversityPeterboroughOntario K9L 0G2Canada Center of Deep Sea Research Institute of OceanologyCenter for OceanMega-ScienceChinese Academy of SciencesQingdao 266071China

The ocean is an important inventory of anthropogenic mercury(Hg),yet the history of anthropogenic Hg accumulation in the ocean remains largely ***-sea corals are an emerging archive of past ocean chemistry,which take in sinking or suspended particulate organic matter as their food *** organic matter would exchange Hg with the local seawater before being consumed by the deepsea *** such,the organics preserved in the coral skeleton may record the Hg evolution of the ambient seawater during the time of coral ***,we report the first data on Hg concentrations variability of a deep-sea proteinaceous coral in the oligotrophic North Pacific at the water depth of 1249 m,in attempt to understand the transfer of anthropogenic Hg into the deep Pacific ocean over the last seven *** find that the Hg concentrations of different coral growth layers have remained relatively constant albeit with considerable short-term variability through *** overall stable Hg concentration of the last seven centuries recorded in our sample suggests that anthropogenic pollution is not yet a clearly resolvable component in the deep oligotrophic North Pacific waters,in agreement with rece nt estimation from modelling works and observational studies of modern seawater *** there is hardly an unambiguous way to separate anthropogenic Hg from the natural background based on recent seawater profiles,our historical data provide valuable information helping to understand the oceanic cycle of Hg through time.

关键词： deep-sea coral mercury deep water particulate organic matter anthropogenic perturbation