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Fish Swimming Traces from the Upper Devonian of Wuhan,South China

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Journal of Earth Science 2023年第4期34卷 1319-1322页

作者： Ruo-Ying fan Rui-wen Zong Yi-Ming Gong State Key Laboratory of Biogeology and Environmental Geology School of Earth SciencesChina University of GeosciencesWuhan 430074China

0 INTRODUCTION Fishes can make diverse traces with various functions such as feeding, resting, dwelling, and nesting(mating). The most common fish trace fossil, however, may be the fish swimming trace Undichna Anderso... 详细信息

关键词： singular sinusoidal Upper

Analysis of limit cycle oscillations of a typical airfoil section with freeplay

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Acta Mechanica Sinica 2013年第4期29卷 583-592页

作者： Si-Jin Zhang Gui-Lin wen fan Peng Zi-Qiang Liu School of Mechanical and Vehicle Engineering Hunan University Institute of Astronautic Aero-Dynamics and Technology

A typical airfoil section system with freeplay is investigated in the paper. The classic quasi-steady flow model is applied to calculate the aerodynamics, and a piecewise-stiffness model is adopted to characterize the non- linearity of the airfoil section＇s freeplay. There are two crit- ical speeds in the system, i.e., a lower critical speed, above which the system might generate limit cycle oscillation, and an upper critical one, above which the system will flutter. Then a Poincar6 map is constructed for the limit cycle os- cillations by using piecewise-linear solutions with and with- out contact in the system. Through analysis of the Poincar6 map, a series of equations which can determine the frequen- cies of period-1 limit cycle oscillations at any flight veloc- ity are derived. Finally, these analytic results are compared to the results of numerical simulations, and a good agree- ment is found. The effects of freeplay value and contact stiffness ratio on the limit cycle oscillation are also analyzed through numerical simulations of the original system. More- over, there exist multi-periods limit cycle oscillations and even complicated ＂chaotic＂ oscillations may occur, which are usually found in smooth nonlinear dynamic systems.

关键词： Freeplay nonlinearity ~ Typical airfoil section ~Limit cycle oscillations ~ Poincar6 map

Science Letters:Three-dimensional conceptual model for service-oriented simulation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第8期10卷 1075-1081页

作者： wen-guang WANG Wei-ping WANG Justyna ZANDER Yi-fan ZHU College of Information System and Management National University of Defense Technology Changsha 410073 China Fraunhofer Institute FOKUS Kaiserin-Augusta-Allee 31 Berlin 10589 Germany

In this letter,we propose a novel three-dimensional conceptual model for an emerging service-oriented simulation paradigm. The model can be used as a guideline or an analytic means to find the potential and possible future directions of the current simulation frameworks. In particular, the model inspects the crossover between the disciplines of modeling and simulation, service-orientation,and software/systems engineering. Finally, two specific simulation frameworks are studied as examples.

关键词： Conceptual model Modeling and simulation Service-oriented architecture Systems engineering

Precise and accurate Ga isotope ratio measurements of geological samples by multi-collector inductively coupled plasma mass spectrometry

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Acta Geochimica 2024年第6期43卷 1054-1064页

作者： Yuxu Zhang Pan Qiao Chuanwei Zhu Haifeng fan Hanjie wen State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of Sciences99 West Lincheng RoadGuiyang 550081Guizhou ProvinceChina School of Earth Sciences and Resources Chang’an University126 Yanta RoadXi’an 710054Shaanxi ProvinceChina College of Resources and Environment University of Chinese Academy of SciencesBeijing 101408China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

Gallium isotope is a potential geochemical tool for understanding planetary processes,environmental pollution,and ore deposit *** reported Ga isotope compositions(δ^(71)Ga NIST994 values)of some international geological standards,such as BCR-2 and BHVO-2 basalts,exhibit inconsistencies between diff erent *** mass spectrometry analysis,we found thatδ^(71)Ga NIST994 values of geological standards with or without the correction of the interference of^(138)Ba^(2+)(mass/charge ratio=69)on 69 Ga show signifi cant isotope off sets,and thus effi cient separation of Ba and correcting the interference of^(138)Ba^(2+)are both crucial to obtain accurateδ^(71)Ga *** comparingδ^(71)Ga NIST994 values(relative to NIST SRM 994 Ga)of the same geostandards from diff erent laboratories,we suggest that the isotopic heterogeneity from NIST SRM 994 Ga is one of the key reasons for the inconsistencies inδ^(71)Ga NIST994 values of BCR-2 and *** facilitate inter-laboratory comparisons,we measured the Ga isotopic compositions of 11 geological reference materials(including Pb-Zn ore,bauxite,igneous rocks,and loess)and two Ga solution standards(NIST SRM 3119a and Alfa Aesar).Theδ^(71)Ga NIST994 andδ^(71)Ga IPGP values of these reference materials vary from 1.12‰to 2.63‰and−0.13‰to 1.38‰,respectively,and can be used to evaluate the precision and accuracy of Ga isotope data from diff erent laboratories.

关键词： Ga isotopes MC-ICP-MS Reference materials Chemical purification Ba interference

Large-area, Flexible Polymer Solar Cell Based on Silver Nanowires as Transparent Electrode by Roll-to-Roll Printing

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Chinese Journal of Polymer Science 2017年第2期35卷 261-268页

作者： Yi-fan Zhao wen-jun Zou Huan Li 吕琨延卫魏志祥 Chinese Academy of Sciences Key Laboratory of Nanosystem and Hierarchical Fabrication Chinese Academy of Sciences Center for Excellence in Nanoscienee National Center for Nanoscience and Technology Beijing 100190 China Department of Environmental Science and Engineering Xi ＇an Jiaotong University Xi ＇an 700049 China

Conventional organic solar cell＇s （OSC） architectures, including rigid transparent substrate （Glass）, conductive electrode （Indium tin oxide, ITO） and small working areas, are widely utilized in organic photovoltaic fields. However, such a structure as well as conventional spin-coating method obviously restrict their industrial application. In this article, we report the deposition of silver nanowires （AgNWs） on the flexible substrate by slot-die printing. The obtained AgNWs films exhibited a high transmittance and a low resistance, and were further used as the transparent conductive electrode ofOSCs. A typical conjugated polymer, poly[（2-5-bis（2-hexyldecyloxy）phenylene）-alt-（5,6-difluoro-4,7-di（thiophen-2-yl）benzo[c] [1,2,5]thiadiazole）] （PPDT2FBT）, was used as the active material to fabricate large-area （7 cm2） solar cells by a slot-die coating process. The power conversion efficiency （PCE） could reach 1.87% initially and further increased to 3.04% by thermal annealing. Compared to the performance of reference cell on ITO substrate, the result indicated that the AgNWs could be developed as an alternative substitute of conductive electrode to fabricate the large-area flexible OSCs by roll-to-roll printing.

关键词： Polymer solar cell Silver nanowires Slot-die Large area Flexible substrate

From Teleoperation to Autonomous Robot-assisted Microsurgery:A Survey

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Machine Intelligence Research 2022年第4期19卷 288-306页

作者： Dandan Zhang Weiyong Si wen fan Yuan Guan Chenguang Yang Department of Engineering Mathematics University of BristolBristol BS81THUK Department of Engineering Design and Mathematics University of the West of EnglandBristol BS161QYUK Bristol Robotics Laboratory Bristol BS161QYUK

Robot-assisted microsurgery(RAMS)has many benefits compared to traditional *** platforms with advanced control strategies,high-quality micro-imaging modalities and micro-sensing systems are worth developing to further enhance the clinical outcomes of *** only a few decades,microsurgical robotics has evolved into a rapidly developing research field with increasing attention all over the *** the appreciated benefits,significant challenges remain to be *** this review paper,the emerging concepts and achievements of RAMS will be *** introduce the development tendency of RAMS from teleoperation to autonomous *** highlight the upcoming new research opportunities that require joint efforts from both clinicians and engineers to pursue further outcomes for RAMS in years to come.

关键词： Robot-assisted microsurgery(RAMS) imaging and sensing teleoperation cooperative control robot learning.

Effect of Deformation Temperatures on Microstructure of AQ80 Magnesium Alloy under Repeated Upsetting-Extrusion

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Acta Metallurgica Sinica(English Letters) 2023年第10期36卷 1649-1664页

作者： Yutian fan Liwei Lu Hongliang Zhao Zhiqiang Wu Yong Xue wen Wang School of Materials Science and Engineering Hunan University of Science and TechnologyXiangtan411201China College of Materials Science and Engineering Zhengzhou UniversityZhengzhou450001China School of Material Science and Engineering North University of ChinaTaiyuan030051China School of Metallurgical Engineering National and Local Joint Engineering Research Center for Functional Materials ProcessingXi’an University of Architecture and TechnologyXi’an710055China

A new repeated upsetting-extrusion (RUE) process was proposed to improve the microstructure and the mechanical properties of Mg alloys. The effects of deformation temperature on the microstructure and microhardness of RUEed AQ80 Mg alloy were studied. The results showed that Mg alloy is subjected to sufficient corner shear deformation, upsetting deformation, and extrusion deformation, resulting in a large and uniformly distributed effective strain after RUE deformation. The microstructure is refined to an average grain size of 2.1 μm by the continuous dynamic recrystallization (CDRX) mechanism at 250 °C. As the temperature increases to 300 °C, the discontinuous dynamic recrystallization (DDRX) mechanism is activated and the average grain size is refined to 1.6 µm by the combined effect of CDRX and DDRX. In comparison to their parent grains, the orientations of the CDRXed grains show a clearly preferred orientation, but those of the DDRXed grains are completely different. At 350 °C, {10-12} extension twins appear in the microstructure, and the twinning-induced recrystallization (TDRX) mechanism plays an important role in grain refinement. With the two strengthening mechanisms of fine-grained strengthening and dislocation strengthening, the microhardness of the 250 °C sample is greatly improved, with an increase of about 35.1% compared to the initial sample.

关键词： AQ80 Mg alloy Repeated upsetting-extrusion Microstructure Microhardness

Assessment of subgrid-scale models in wall-modeled large-eddy simulations of turbulent channel flows

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Journal of Hydrodynamics 2023年第3期35卷 407-416页

作者： Wei-wen Zhao Fu-chang Zhou Guo-qing fan De-cheng Wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Wuhan Second Ship Design and Research Institute Wuhan 430205China

Considering the demanding of grid requirements for high-Reynolds-number wall-bounded flow,the wall-modeled large-eddy simulation(WMLES)is an attractive method to deal with near wall ***,the effect of subgrid-scale(SGS)models for wall-bounded turbulent flow in combination with wall stress models is still *** this paper,turbulent channel flow at Reτ=1000 are numerically simulated by WMLES in conjunction with four different SGS models,i.e.,the wall-adapting local eddy-viscosity model,the dynamic Smagorinsky model,the dynamic SGS kinetic energy model and the dynamic Lagrangian *** mean velocity profiles are compared with the law of the wall,and the velocity fluctuations are compared with direct numerical simulation *** energy spectrum of velocity and wall pressure fluctuations are presented and the role of SGS models on predicting turbulent channel flow with WMLES is discussed.

关键词： Wall-modeled large-eddy simulation(WMLES) subgrid-scale(SGS)model turbulent channel flow energy spectra

FOOD SYSTEMS TRANSFORMATION:CONCEPTS,MECHANISMS AND PRACTICES

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Frontiers of Agricultural Science and Engineering 2023年第1期10卷 1-3页

作者： Shenggen fan ting MENG Academy of Global Food Economics and Policy(AGFEP) College of Economics and ManagementChina Agricultural UniversityBeijing 100083China

The global food systems face significant interrelated and complex challenges,including climate change,extreme weather events,natural resource depletion,biodiversity loss,emerging plant and animal diseases,conflict and trade *** number of global populations that lacked access to adequate food sharply increased during the COVID-19 *** is estimated that in 2021,about 702 million to 828 million people around the world suffer from hunger,with an increase of 150 million people alone due to the outbreak of the global COVID19 pandemic[1].Reduced incomes,food price inflations and continued supply chain disruptions will lead to even more severe and widespread increases in global food insecurity if urgent action is not taken,affecting vulnerable households in almost every country.

关键词： sharply continued extreme