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Bio-inspired polygonal skeleton structure for vibration isolation:Design,modelling,and experiment

Science China(Technological Sciences) 2020年第12期63卷 2617-2630页

作者： YAN Ge WANG Sen ZOU HongXiang ZHAO LinChuan gao QiuHua ZHANG WenMing State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Aerospace Control Technology Institute Shanghai 201109China

Inspired by the safe landing of a cat falling from a high altitude,a bio-inspired polygonal skeleton(BIPS) structure is proposed,and its nonlinear characteristics are systematically studied to explore its potential application in the suppression of vibration. The polygon is formed by the skeleton structure of the cat’s entire body and the ground. The BIPS system consists of two symmetrical bionic legs with three robs(as skeleton) and four horizontal springs(as muscle). Two bionic legs are connected through the bearing platform(as spine),which could adjust the distance between the two bionic legs. A theoretical model is developed to characterize its stiffness nonlinearity through geometrical and mechanical analysis. Parameter analysis reveals that the BIPS structure has diverse stiffness,including nonlinear positive stiffness and negative stiffness. By imitating adjustment of leg posture and telescopic function of the spine(control the distance between legs),these flexible stiffness properties can be adjusted by structure parameters. In addition,the load capacity and working range can also be designed by the length of the bars,the initial angle,the mounting position,and the spring stiffness. The experimental setup is established,and the vibration isolation performance under various excitation is tested. The experimental results verify the accuracy of the dynamic model and also show that the proposed BIPS structure can suppress the vibration effectively under a variety of excitations. These peculiarities may provide potential possibility of an innovative approach to passive vibration control and isolation.

关键词： bio-inspired polygonal skeleton structure nonlinear stiffness passive vibration isolator

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Solving Strength–Toughness Dilemma in Superhard Transition-Metal Diborides via a Distinct Chemically Tuned Solid Solution Approach

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Research 2023年第3期6卷 473-483页

作者： Xinlei Gu Chang Liu Xinxin gao Kan Zhang Weitao Zheng Changfeng Chen State Key Laboratory of Superhard Materials Department of Materials Science and Key Laboratory of Automobile MaterialsMOEJilin UniversityChangchun 130012China International Center for Computational Methods&Software College of PhysicsJilin UniversityChangchun 130012China Department of Physics and Astronomy University of NevadaLas VegasNV 89154USA

Solid solution strengthening enhances hardness of metals by introducing solute atoms to create local distortions in base crystal lattice,which impedes dislocation motion and plastic deformation,leading to increased strength but reduced ductility and *** sharp contrast,superhard materials comprising covalent bonds exhibit high strength but low toughness via a distinct mechanism dictated by brittle bond deformation,showcasing another prominent scenario of classic strength–toughness tradeoff *** this less explored and understood problem presents a formidable challenge that requires a viable strategy of tuning main load-bearing bonds in these strong but brittle materials to achieve concurrent enhancement of the peak stress and related strain ***,we demonstrate a chemically tuned solid solution approach that simultaneously enhances hardness and toughness of superhard transition-metal diboride Ta_(1−x)Zr_(x)B_(2).This striking phenomenon is achieved by introducing solute atom Zr that has lower electronegativity than solvent atom Ta to reduce the charge depletion on the main load-bearing B–B bonds during indentation,leading to prolonged deformation that gives rise to notably higher strain range and the corresponding peak *** finding highlights the crucial role of properly matched contrasting relative electronegativity of solute and solvent atoms in creating concurrent strengthening and toughening and opens a promising avenue for rational design of enhanced mechanical properties in a large class of transition-metal *** strategy of concurrent strength–toughness optimization via solute-atom-induced chemical tuning of the main load-bearing bonding charge is expected to work in broader classes of materials,such as nitrides and carbides.

关键词： toughness deformation strengthening

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Characteristics of atmospheric boundary layer structure and its influencing factors under different sea and land positions in Europe

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Earth and Planetary Physics 2023年第2期7卷 257-268页

作者： YeHui Zhang XinPeng Yong HouFu Zhou HaiYang gao Na Yang Key Laboratory of Hydrometeorological Disaster Mechanism and Warning of Ministry of Water Resources Nanjing University of Information Science and TechnologyNanjing 210044China Anhui Institute of Meteorology Sciences Anhui Key Laboratory of Atmospheric Science and Satellite Remote SensingHefei 230031China School of Atmospheric Physics Nanjing University of Information Science and TechnologyNanjing 210044China

This study identifies quantitatively the dominant contributions of meteorological factors on the development of the boundary layer heights(BLH)in the European region,based on 32 years(1990-2021)of radiosonde *** spatial variability of the BLH is further discussed by location,by classifying recording stations as inland,coastal,or *** find that the BLH in Europe varies considerably from day to night and with the *** BLH is higher in winter and lower in summer,with the highest BLH recorded at coastal *** BLH at coastal stations shows a bimodal structure with peaks in spring and autumn;at inland and bay stations,daytime BLH is lower in winter and higher in *** daily amplitudes of BLH at the inland and bay stations are stronger than those at coastal *** on our multiple linear regression analysis and our decoupling analysis of temperature and specific humidity,we report that the development of the nighttime BLH at all types of stations is strongly dominated by the variations of surface wind speed(and,at coastal stations,wind directions).The main contributors to daytime BLH are the near-surface temperature variability at most coastal and inland stations,and,at most bay stations,the variation of the near-surface specific humidity.

关键词： atmospheric boundary layer height wind surface temperature specific humidity decoupling

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Entity generation algorithm based on reference expansion

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Journal of Electronic Science and Technology 2023年第3期21卷 63-72页

作者： Jia-Jia Ruan Xi-Xu He Min Zhang Yuan gao Office of Scientific Research&Development University of Electronic Science and Technology of ChinaChengdu611731China School of Resources and Environment University of Electronic Science and Technology of ChinaChengdu611731China Information Center University of Electronic Science and Technology of ChinaChengdu611731China Archives University of Electronic Science and Technology of ChinaChengdu611731China

The extraction and understanding of text knowledge become increasingly crucial in the age of big *** of the current research areas in the field of natural language processing(NLP)is how to accurately understand the text and collect accurate linguistic information because Chinese vocabulary is diverse and *** paper mainly studies the candidate entity generation module of the entity link *** candidate entity generation module constructs an entity reference expansion algorithm to improve the recall rate of candidate *** order to improve the efficiency of the connection algorithm of the entire system while ensuring the recall rate of candidate entities,we design a graph model filtering algorithm that fuses shallow semantic information to filter the list of candidate entities,and verify and analyze the efficiency of the algorithm through *** analyzing the related technology of the entity linking algorithm,we study the related technology of candidate entity generation and entity disambiguation,improve the traditional entity linking algorithm,and give an innovative and practical entity linking *** recall rate exceeds 82%,and the link accuracy rate exceeds 73%.Efficient and accurate entity linking can help machines to better understand text semantics,further promoting the development of NLP and improving the users’knowledge acquisition experience on the text.

关键词： Chinese Wikipedia Entity reference expansion Graph model

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Direct imaging and mechanism study of C_(6)α-olefin adsorption on faujasite and Linde Type A zeolites

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Nano Research 2022年第6期15卷 5322-5330页

作者： Ruihan Yang Xiao Chen Junxiang Ma Yuan gao Yujun Wang Guangsheng Luo State Key Lab of Chemical Engineering Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Lu’an Chemical Group CO. LTD.Changzhi046299China

Linearα-olefins are important chemical raw *** purifyα-olefins from a high-temperature Fischer–Tropsch synthetic oil,it is necessary to separate theα-olefins from the paraffins,which is *** separation by zeolites is a promising alternative to energy-intensive distillation forα-olefin/paraffin *** integrated differential phase-contrast scanning transmission electron microscopy(iDPC-STEM)technique is used in combination with density functional theory(DFT)simulations and batch adsorption experiments to study the adsorption behavior of C_(6)α-olefins and the mechanism of selective adsorption of C_(6)α-olefin/*** electron microscopy real-space imaging of the atomic frameworks of the faujasite(FAU)and Linde Type A(LTA)zeolites and the C_(6)α-olefin-adsorption positions on their lattices is achieved through *** images provide direct evidence that C_(6)α-olefins preferentially adsorb at the edges of the FAU and LTA zeolite *** calculations further reveal the relationship between host–guest interactions and different molecular *** and experimental results also show that the presence of calcium cations can enhance the selectivity of zeolites forα-olefin/paraffin *** work provides a means to investigate the behavior of guest molecules and the host–guest interactions in the adsorption or catalytic process of nanoporous materials.

关键词： electron microscopy host-guest interactions adsorption separation α-olefins zeolites

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Spatiotemporal evolution of ecosystem service value and topographic gradient effect in the Da-Xiao Liangshan Mountains in Sichuan Province,China

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Journal of Mountain Science 2023年第8期20卷 2344-2357页

作者： JIN Tao CHEN Yang SHU Bo gao Min QIU Jian School of Architecture Southwest Jiaotong UniversityChengdu 611756China Leshan Municipal Bureau of Planning and Natural Resources Leshan 614000China School of Architecture and Civil Engineering Xihua UniversityChengdu 610039China

The Da-Xiao Liangshan mountains are critical ecological function areas and essential ecological barriers in the upper reaches of the Yangtze River in *** study selected a total of six periods of land use land cover(LULC)data from 1995 to 2020,to estimate the ecosystem service value(ESV)and analyzed its spatiotemporal evolution and topographic gradient *** results showed that:(1)The ESV increased by 1.1 billion yuan,with an increase rate of 1.47%from 1995 to *** time periods,2005–2010 and 2015–2020,showed more significant increases than other periods.(2)The elevation and slope of mountainous areas determine the type of land use and further influence the spatial pattern of ESV.(3)Although woodland and grassland are the main land use types of the study area(more than 90%),the hydrological regulation function of the water area partially compensated for the impact of the encroachment of the built-up area on the ESV of grassland.(4)The spatial distribution of ESVs showed an inverted V-shaped characteristic as the topographic gradient increased,with the dominant position being the 5th topographic gradient ***,this study provided relevant recommendations for ecosystem protection and *** findings of this study clarified the influence of topographical factors on the spatial differentiation of ESV and provided novel insights into ecosystem protection.

关键词： Ecosystem service value(ESV) Dynamic evolution Terrain gradient effect Spatial pattern Liangshan Yi region

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The upper bound on the tensor-to-scalar ratio consistent with quantum gravity

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Communications in Theoretical Physics 2021年第7期73卷 115-120页

作者： Lina Wu Qing gao Yungui Gong Yiding Jia Tianjun Li School of Sciences Xi’an Technological UniversityXi’an 710021China School of Physical Science and Technology Southwest UniversityChongqing 400715China School of Physics Huazhong University of Science and TechnologyWuhanHubei 430074China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

We consider the polynomial inflation with the tensor-to-scalar ratio as large as possible which can be consistent with the quantum gravity(QG) corrections and effective field theory(EFT). To get a minimal field excursion ΔΦ for enough e-folding number N, the inflaton field traverses an extremely flat part of the scalar potential, which results in the Lyth bound to be violated. We get a CMB signal consistent with Planck data by numerically computing the equation of motion for inflaton Φ and using Mukhanov–Sasaki formalism for primordial spectrum. Inflation ends at Hubble slow-roll parameter ε_(1)^(H)=1 or a=0. Interestingly, we find an excellent practical bound on the inflaton excursion in the format a+b√r, where a is a tiny real number and b is at the order 1. To be consistent with QG/EFT and suppress the high-dimensional operators, we show that the concrete condition on inflaton excursion is M_(PI)/△_(Ф)<0.2×√10≈0.632. For n_(s)= 0.9649,N_(e)= 55, and M_(PI)/△_(Ф)<0.632 MPl, we predict that the tensor-to-scalar ratio is smaller than 0.0012 for such polynomial inflation to be consistent with QG/EFT.

关键词： polynomail inflation Lyth bound tensor-to-scalar ratio

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Margin trading, short selling, and bond yield spread

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China Journal of Accounting Research 2018年第1期11卷 51-70页

作者： Kaijuan gao Wanfa Lin Hunan University Wuhan University

Using a quasi-natural experiment, this study examines the effects of margin trading and short selling on bond yield spread in China. It finds that both margin trading and short selling can reduce bond yield spread. Additionally, it finds that margin trading lowers firms' debt ratios and increases their credit ratings, which explains the reduced spread. In other words, margin trading can impact investors' decisions by revealing positive information about a *** finding is that short selling lowers the bond yield spread by decreasing earnings management, suggesting that short selling has an impact on investors' decisions through its effect on corporate governance. Our results suggest that margin trading transmits positive information and short selling impacts firms' policies. These results provide support for future regulations of margin trading and short selling.

关键词： Margin trading Short selling Bond yield spread Information spillover

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Marine Mobile Wireless Channel Modeling Based on Improved Spatial Partitioning Ray Tracing

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China Communications 2020年第3期17卷 1-11页

作者： Zhibin gao Bang Liu Zhipeng Cheng Canbin Chen Lianfen Huang Department of Communication Engineering Xiamen UniversityXiamen 361005China China Contribution Bank Fintech Xiamen 361005China

In 5G era,it is expected to achieve wireless network coverage including offshore *** of marine wireless channels is the basis of constructing a marine communication *** this paper,a communication scene between an unmanned aerial vehicle(UAV)and a boat is simulated to study the marine wireless ***,an improved spatial partitioning ray tracing algorithm is proposed to track the propagation path of electromagnetic waves at sea ***,a mobile channel is simulated and modeled based on the track ***,a loss measurement is carried out in the coastal waters based on the simple wireless channel loss measuring platform,and a path loss propagation model is *** we compare the actual measurement data with the simulation results and find that the two are have good consistency,which further verifies the reliability of the simulation.

关键词： marine wireless channel ray tracing channel modeling path loss

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Efficient flexible dye-sensitized solar cells from rear illumination based on different morphologies of titanium dioxide photoanode

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Journal of Semiconductors 2024年第2期45卷 67-73页

作者： Zhe He Gentian Yue Yueyue gao Chen Dong Furui Tan School of Future Technology and Henan Key Laboratory of Photovoltaic Materials Henan UniversityKaifeng 475004China Zhenjiang Mars Photoenergy Technology Co. LtdZhenjiang 212011China

The TiO_(2) with nanoparticles(NPs),nanowires(NWs),nanorods(NRs)and nanotubes(NTs)structures were prepared by using a in-situ hydrothermal technique,and then proposed as a photoanode for flexible dye-sensitized solar cell(FDSSC).The influences of the morphology of TiO_(2) on the photovoltaic performances of FDSSCs were *** rear illumination of 100 mW·cm^(−2),the power conversion efficiencies of FDSSCs achieved 6.96%,7.36%,7.65%,and 7.83%with the TiO_(2) photoanodes of NPs,NWs,NRs,and NTs and PEDOT counter *** FDSSCs based on TiO_(2) NRs and NTs photoanodes have higher short circuit current densities and power conversion efficiencies than that of the *** enhanced power conversion efficiency is responsible for their nanotubes and rod-shaped ordered structures,which are more beneficial to transmission of electron and hole in semiconductor compared to the TiO_(2) nanoparticles and nanowires disordered structure.

关键词： dye-sensitized solar cells photoanode TiO_(2) morphology

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