检索结果-南通市图书馆

Structural and Chemical Characterization of the Ediacaran Embryo-Like Fossils via the Combination of 3D-XRM and FIB-SEM Approaches

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

Journal of Earth Science 2024年第4期35卷 1204-1214页

作者： Qian Chen weichen sun Suping Wu Zongjun Yin State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing210008China University of Chinese Academy of Sciences Nanjing211135China

The three-dimensional(3D)morphology,anatomy,and in-situ chemical composition analysis of fossils are crucial for systematic paleontology and determining their phylogenetic *** electron microscopy(SEM)coupled with energy-dispersive X-ray spectroscopy(EDS),offers valuable structural and chemical information for the analysis of ***,its primary limitation is the restriction to two-dimensional surface data,which limits the exploration of fossils’3D ***,3D X-ray microscopy(3D-XRM),also known as a novel form of micro-computed tomography(micro-CT)facilitates the non-destructive 3D reconstruction of fossil ***,it lacks the capability to provide in-situ compositional *** the constraints inherent in these individual techniques,and in response to the evolving requirements of paleontological research,this study introduces an integrated approach that combines 3D-XRM with EDS-coupled focused ion beam scanning electron microscopy(FIB-SEM).This innovative strategy is designed to synergize the advantages of both techniques,thereby addressing challenges that conventional methods *** enables the rapid identification of regions of interest(ROI)within fossil specimens at micrometer ***,this method collects detailed data on both 3D structures and chemical compositions at the nanometer scale for the identified *** integrated approach represents a significant advancement in paleontological and geological research methodologies,promising to meet the increasing demands of these fields.

关键词： Embryo-like microfossils structural and chemical characterization 3D-XRM FIB-SEM 3D reconstruction

Pressure stimulated current in progressive failure process of combined coal-rock under uniaxial compression:Response and mechanism

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2024年第2期34卷 227-243页

作者： Tiancheng Shan Zhonghui Li Xin Zhang Haishan Jia Xiaoran Wang Enyuan Wang Yue Niu Dong Chen weichen sun Dongming Wang State Key Laboratory of Coal Mine Disaster Prevention and Control China University of Mining and TechnologyXuzhou 221116China National Engineering Research Center for Coal Gas Control China University of Mining and TechnologyXuzhou 221116China School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China

Effective monitoring of the structural health of combined coal-rock under complex geological conditions by pressure stimulated currents(PSCs)has great potential for the understanding of dynamic disasters in underground *** reveal the effect of this way,the uniaxial compression experiments with PSC monitoring were conducted on three types of coal-rock combination samples with different strength *** mechanism explanation of PSCs are investigated by resistivity test,atomic force microscopy(AFM)and computed tomography(CT)methods,and a PSC flow model based on progressive failure process is *** influence of strength combinations on PSCs in the progressive failure process are *** results show the PSC responses between rock part,coal part and the two components are different,which are affected by multi-scale fracture characteristics and electrical *** the rock strength decreases,the progressive failure process changes obviously with the influence range of interface constraint effect decreasing,resulting in the different responses of PSC strength and direction in different parts to fracture *** PSC flow model is initially validated by the relationship between the accumulated charges of different *** results are expected to provide a new reference and method for mining design and roadway quality assessment.

关键词： Combined coal-rock Pressure stimulated current Progressive failure process Mechanism Flow model

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

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第4期67卷 919-949页

作者： Lang sun Malik Muhammad Saud Sajid KHAN Chuan YANG Zhixin sun Bing PAN Shehryar AHMED Lanyun MIAO weichen sun Chunlin HU Xiaojuan sun Cui LUO Bo CHEN Zongjun YIN Fangchen ZHAO Guoxiang LI Maoyan ZHU State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

The complex evolutionary history of the Qinghai-Tibetan Plateau and its surrounding areas,including the continental blocks(Indian,Lhasa,South Qiangtang,Tarim,Olongbuluk,Central Qilian,Alxa,North China,Yangtze,Central Iran and Oman)and the orogenic belts between them,has long been the frontier in Earth science *** Cryogenian and Ediacaran strata are extensively distributed in these ***,relatively complete Cryogenian and Ediacaran successions have been discovered in Oman,Indian,Yangtze,and Tarim blocks,while only the Ediacaran successions have been reported in Iran,the South Qiangtang,Central Qilian,Alxa,and North China *** on previous studies together with the integration of new materials and advancement obtained through the Second Tibetan Plateau Scientific Expedition and Research,this review aims to synthesize a correlative stratigraphic framework of the representative Cryogenian and Ediacaran sequences from the Qinghai-Tibetan Plateau and its surrounding ***,the Cryogenian and Ediacaran biotas and major geological events in these areas are comprehensively discussed in aspects of current research *** results indicate that,in general,Ediacaran fossils of each area exhibit distinct features in preservation and assemblage composition,but the typical late Ediacaran fossils Cloudina and Shaanxilithes have been reported from most of these *** addition to the two global Cryogenian glaciations,late Ediacaran glaciogenic deposits are extensively recorded in the areas within and around the northern QinghaiTibetan Plateau(including the North China,Alxa,Central Qilian,Olongbuluk,and Tarim blocks,and the North Qilian Accretionary Belt),as well as central and southern ***,further research is required to determine the age,distribution,and origin of these late Ediacaran glaciogenic ***,the middle Ediacaran DOUNCE/Shuram Excursion is widely documented in the Qinghai-Tibetan Plateau and its surroundi

关键词： Qinghai-Tibetan Plateau Cryogenian Ediacaran Stratigraphy Palaeogeography Biota Gondwana

Influence of introducing Zr,Ti,Nb and Ce elements on externally solidified crystals and mechanical properties of high-pressure die-casting Al–Si alloy

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 147-153页

作者： Junjie Li Wenbo Yu Zhenyu sun weichen Zheng Liangwei Zhang Yanling Xue Wenning Liu Shoumei Xiong Center of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Traffic&Transportation Engineering Central South UniversityChangsha 410075China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile *** can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated ***,the development of non-heat treatment Al alloys is becoming the hot *** addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of *** achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and *** influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic *** results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased ***,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical *** introduction of Ce resulted in the poisoning effect and reduced mechanical properties.

关键词： aluminium alloy high-pressure die-casting externally solidified crystals non-heat treatment

Pose Measurement and Tracking of Non-cooperative Satellite Based on Stereo Vision

在线全文

学校读者我要写书评

暂无评论

Pose Measurement and Tracking of Non-cooperative Satellite B...

冲击破坏过程微震波形多重分形及其时变响应特征

第40届中国控制会议

作者： Wuchen Bai Lingling Shi Xiaolong Xiao weichen sun Xin Jin School of Mechanical Engineering Beijing Institute of Technology

To realize non-cooperative satellites captured by a space robot, a method for autonomous measurement and tracking of space non-cooperative satellites based on stereo vision is proposed. The pose measurement takes the general structure of satellites, i.e. satellite frame and satellite-rocket docking ring as recognition features, which facilitates edge determination by the ellipse center. Then, the 3D coordinates of corner points are obtained through binocular stereo vision by which the pose of the satellite can be subsequently computed. On this basis, kernelized correlation filter（KCF） is used to track the identified corner points. The measurement and tracking results are verified through the visual simulation system. The results show that the methods can realize relative position and attitude measurement for non-cooperative spacecraft with high accuracy and the recognition algorithm can retain effective when features are partially occluded.

关键词： Non-cooperative Satellite Pose Measurement Target Tracking Stereo Vision

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

中国矿业大学学报 2017年第5期46卷 1007-1013页

作者：李楠李保林陈栋孙炜辰中国矿业大学煤炭资源与安全开采国家重点实验室江苏徐州221116 中国矿业大学安全工程学院江苏徐州221116 中国矿业大学孙越崎学院江苏徐州221116

采用多重分形理论研究了冲击破坏过程不同阶段微震波形的多重分形及其时变响应特征,提出了将最大多重分维数D_(maxq),多重分形谱参数Δα和Δf(α)作为煤矿微震波形多重分形特征量.研究表明:冲击诱发微震波形的多重分形特征明显强于冲... 详细信息

采用多重分形理论研究了冲击破坏过程不同阶段微震波形的多重分形及其时变响应特征,提出了将最大多重分维数D_(maxq),多重分形谱参数Δα和Δf(α)作为煤矿微震波形多重分形特征量.研究表明:冲击诱发微震波形的多重分形特征明显强于冲击前后的常规微震波形;D_(maxq)和Δα能够反映微震波形的非均匀性和波动程度,D_(maxq)和Δα越大,微震波形的非均匀性和波动性越强,多重分形特征越明显;Δf(α)是反映微震波形信号中大小峰值所占比例的度量,Δf(α)越小表示微震波形中大峰值所占比例越大,即微震波能量越大.冲击破坏前微震波形多重分形特征量D_(maxq),Δα和Δf(α)的时变响应具有明显的规律性,当D_(maxq)或Δα超过其下临界值并持续增加接近其上临界值时,或当Δf(α)小于其上临界值并持续降低接近其下临界值时,特别是当上述3种时变响应特征同时发生时,极易发生大的冲击破坏事件;微震波形多重分形特征量D_(maxq),Δα和Δf(α)的时变响应特征能够作为有效的前兆信息对冲击地压进行监测预警.

关键词：冲击地压微震波形广义信息维多重分形谱特征量时变响应

在线全文

学校读者我要写书评

暂无评论

对课余训练运动员疲劳问题的探讨

安徽体育科技 2002年第1期23卷 60-61页

作者：戴霞孙维成淮南联合大学淮南232000 淮南市九中淮南232000

在课余训练中 ,高强度、大负荷训练 ,仍然是训练中的主要手段和显著特点。训练后能快速消除疲劳 ,是提高运动成绩的主要条件 ,是教练员和运动员亟待解决的主要问题之一。本文就疲劳产生的原因 ,外在表现 ,疲劳消除的方法提出几点看法。

关键词：课余训练运动员大负荷训练外在表现运动成绩教练员疲劳消除消除疲劳问题原因

卫星图像辐射量归一化技术研究及其在城市土地动态监测的应用

在线全文

学校读者我要写书评

暂无评论

工程勘察 2009年第9期37卷 65-69页

作者：韩勇陈戈孙为晨甘宇亮中国海洋大学海洋遥感研究所山东青岛266003 青岛市勘察测绘研究院山东青岛266033

高分辨率卫星遥感技术是目前监测城市动态发展变化的有效手段,本文研究卫星图像辐射量归一化技术（RNIM）,实现了对青岛市多时段ETM标准化处理,使同一地区、不同时域的卫星图象的辐射量建立了统一标准,结合图象分类提取技术,实现了青岛... 详细信息

高分辨率卫星遥感技术是目前监测城市动态发展变化的有效手段,本文研究卫星图像辐射量归一化技术（RNIM）,实现了对青岛市多时段ETM标准化处理,使同一地区、不同时域的卫星图象的辐射量建立了统一标准,结合图象分类提取技术,实现了青岛市1996年、2000年、2001年和2002年四个时段的青岛市区数据的自动提取,根据提取的成果,分析了1996年~2002年青岛城市土地利用发展变化的趋势和规律,为政府管理提供决策依据,实现城市的可持续发展。

关键词： TM/ETM 辐射量归一化动态监测

Safe flight corridor constrained sequential convex programming for efficient trajectory generation of fixed-wing UAVs

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2025年第1期38卷 537-550页

作者： Jing sun Guangtong XU Zhu WANG Teng LONG Jingliang sun School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Huzhou Institute Zhejiang UniversityHuzhou 313000China Department of Automation North China Electric Power University(Baoding)Baoding 071003China

Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally *** paper proposes a Safe Flight Corridor constrained Sequential Convex Programming(SFC-SCP)to improve the computation efficiency and reliability of trajectory ***-SCP combines the front-end convex polyhedron SFC construction and back-end SCP-based trajectory optimization.A Sparse A^(*)Search(SAS)driven SFC construction method is designed to efficiently generate polyhedron SFC according to the geometric relation among obstacles and collision-free *** transforming the nonconvex obstacle-avoidance constraints to linear inequality constraints,SFC can mitigate infeasibility of trajectory planning and reduce computation ***,SCP casts the nonlinear trajectory optimization subject to SFC into convex programming subproblems to decrease the problem *** addition,a convex optimizer based on interior point method is customized,where the search direction is calculated via successive elimination to further improve *** experiments on dense obstacle scenarios show that SFC-SCP can generate dynamically feasible safe trajectory *** studies with state-of-the-art SCP-based methods demonstrate the efficiency and reliability merits of ***,the customized convex optimizer outperforms off-the-shelf optimizers in terms of computation time.

关键词： Fixed-wing unmanned aerial vehicle Efficient trajectory planning Safe flight corridor Sequential convex programming Customized convex optimizer