检索结果-南通市图书馆

Simulation of critical transitions and vulnerability assessment of Tibetan Plateau key ecosystems

Journal of Mountain Science 2022年第3期19卷 673-688页

作者： yang Fei MA Chao FANG Hua-jun State Key Laboratory of resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research of Chinese Academy of SciencesBeijing 100101China College of resources and Environment University of Chinese Academy of SciencesBeijing 100049China Jiangsu Center for Collaborative Innovation in Geographical Information resource Development and Application Nanjing 210023China

Critical transitions in ecosystems may imply risks of unexpected collapse under climate changes,especially vegetation often responds sensitively to climate *** type of vegetation ecosystem states could present alternative stable states,and its type could signal the critical transitions at tipping points because of changed climate or other *** study analyzed the distribution of four key vegetation ecosystem types:desert,grassland,forest-steppe ecotone and forest,in Tibetan Plateau in China,using the latent class analysis method based on remote sensing data and climate *** study analyzed the impacts of three key climate factors,precipitation,temperature,and sunshine duration,on the vegetation states,and calculated the critical transition tipping point of potential changes in vegetation type in Tibetan Plateau with the logistic regression *** studied results showed that climatic factors greatly affect the vegetation states and vulnerability of the Tibetan *** comparison with temperature and sunshine duration,precipitation shows more obvious impact on differentiations of the vegetations status *** precipitation tipping point for desert and grassland transition is averagely 48.0 mm/month,70.7 mm/month for grassland and forest-steppe ecotone,and 115.0 mm/month for forest-steppe ecotone and *** temperature and sunshine duration only show different probability change between vegetation and non-vegetation type,but produce opposite *** Tibetan Plateau,the transition tipping points of vegetation and nonvegetation are about 12.1°C/month and 173.6 h/month for the temperature and sunshine duration,***,vulnerability maps calculated with the logistic regression results presented the distribution of vulnerability of Tibetan Plateau key *** vulnerability of the typical ecosystems in the Tibetan Plateau is low in the southeast and is high in the *** meteorological factors affect tree co

关键词： Vulnerability Transition Tipping point Tibetan Plateau Latent class analysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

First Principles Study on FeAs Single Layers

引用

Chinese Journal of Chemical Physics 2009年第2期22卷 139-142页

作者： jun Dai Zhen-yu Li Jin-long yang Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei 230026 China

FeAs^- single layer is tested as a simple model for LaFeAsO and BaFe2As2 based on firstprinciples calculations using generalized gradient approximation （GGA） and GGA＋U. The calculated single-layer geometric and electronic structures are inconsistent with that of bulk materials. The bulk collinear antiferromagnetic ground state failed to be obtained in the FeAs^- single layer. The monotonous behavior of the Fe-As distance in z direction upon electron or hole doping is also in contrast with bulk materials. The results indicate that, in LaFeAsO and BaFe2As2, interactions between FeAs layer and other layers beyond simple charge doping are important, and a single FeAs layer may not represent a good model for Fe based superconducting materials.

关键词： Superconductivity FeAs layer Magnetism Density functional theory

来源：

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

Multi-walled carbon nanotubes added to Na_2CO_3/MgO composites for thermal energy storage

引用

Particuology 2014年第4期12卷 56-60页

作者： Feng Ye Zhiwei Ge Yulong Ding jun yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences Institute of Particle Science and Engineering School of ProcessEnvironmental and Materials EngineeringUniversity of LeedsLeeds LS2 9JTUK

Na2CO3/MgO composites with added multi-walled carbon nanotubes （MWCNTs） were prepared and tested as phase change materials （PCMs） for thermal energy storage. Na2CO3/MgO composite PCMs were prepared and their chemical compatibility and thermal stability were studied. MWCNTs introduced with Na2CO3/MgO composite PCMs were also investigated and scanning electron microscopy （SEM） characterization was used to demonstrate the uniform dispersion of MWCNTs in Na2CO3/MgO composite PCMs. The composites with added MWCNTs still display good thermal stability with mass losses lower than 5%. Introducing MWCNTs into composite Na2CO3/MgO PCMs by material formation/calcination *** enhances the thermal conductivity of the composite PCMs. The thermal conductivity of the composite PCMs was found to increase with an increase in the weight fraction of the added MWCNTs and an increase in the testing temperature. This study may present a promising way to prepare high temperature phase change materials with superior properties such as improved thermal stability.

关键词： Phase change materialsCompositeMulti-walled carbon nanotubesThermal conductivityChemical compatibilityThermal energy storage

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Facile preparation of holmium(Ⅲ)-doped carbon nanodots for fluorescence/magnetic resonance dual-modal bioimaging

引用

Chinese Chemical Letters 2018年第8期29卷 1277-1280页

作者： Yaning Fang jun Jia jun yang junhui Zheng Changqing Yi Key Laboratory of Sensing Technology and Biomedical Instruments of Guangdong Province School of Engineering. Sun Yat-sen University Guangzhou 510006 China Guangdong General Hospital Guangzhou 510080 China research Institute of Sun Yat-sen University in Shenzhen Shenzhen 618057 China

In this work, we report the synthesis of holmium（III）-doped carbon nanodots（Ho BCDs） as fluorescence/magnetic resonance（FL/Mr） dual-modal imaging probes via a facile hydrothermal process using citrate acid（CA）, branched-polyethylenimine（BPEI） and diethylenetriamine pentaacetic acid hydrate holmium（III） dihydrogen salt（Ho-DTPA） as carbon source, passivating reagent and holmium source, *** thus prepared Ho BCDs exhibited ultra-small particle size（~4 nm）, high water solubility and bright fluorescence with an absolute quantum yield of 8%. Additionally, grey-scaled T_1-weighted images of Ho BCDs solution appeared to be apparently brighter than that of deionized water and un-doped blue carbon nanodots（BCDs） solution. In addition, in vitro toxicity assay validated superior biocompatibility of Ho BCDs. Using He La cells as models, Ho BCDs-treated cells were observed to emit blue fluorescence located both in plasma and nucleus, and presented positive contrast enhancement in T_1-weighted images, suggesting their potentials for practical biomedical applications.

关键词： Carbon dots Holmium Dual-modal imaging Fluorescence imaging Magnetic resonance imaging

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of the Northeast China revitalization Strategy on regional Economic Growth and Social Development

引用

Chinese Geographical Science 2020年第5期30卷 791-809页

作者： rEN Wanxia XUE Bing yang jun LU Chengpeng Key Laboratory of Pollution and Environment Engineering Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China Key Lab for Environmental Computation and Sustainability of Liaoning Province Shenyang 110016China Ji-angho Architecture Northeastern UniversitShenyang 110016China Institute for County Economy Developments&rural revi-talization Strategy Lanzhou UniversityLanzhou 730000China

Measuring the economic and social effects of the Northeast China revitalization Strategy is critical to addressing regional sustainable development in China. To shed light on this issue, an integrated perspective was adopted that is combined with the difference-in-differences method to measure the effects of the strategy on economic growth and social development in Northeast China. The findings suggest that the strategy has significantly improved regional economic growth and per-capita income by increasing its gross domestic product(GDP) and GDP per capita by 25.70% and 46.00%, respectively. However, the strategy has significantly worsened the regional employment in the secondary industry of the region. In addition, the strategy has not significantly improved regional infrastructural road, education investment or social security, and has had no significant effect on mitigating regional disparity. In addition, the policy effects are highly heterogeneous across cities based on city size and characteristics. Therefore, there is no simple answer regarding whether the Northeast China revitalization Strategy has reached its original goals from an integrated perspective. The next phase of the strategy should emphasize improving research and development(r&D) and human capital investments based on urban heterogeneity to prevent conservative path-dependency and the lock-in of outdated technologies.

关键词： policy evaluation difference-in-differences(DID)method regional disparity urban heterogeneity regional revitalization old industrial base Northeast China

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nonlinear composite bilateral control framework for n-DOF teleoperation systems with disturbances

引用

Science China(Information Sciences) 2018年第7期61卷 182-199页

作者： Zhenhua ZHAO jun yang Cunjia LIU Wen-Hua CHEN School of Automation Southeast University Key Laboratory of Measurement and Control of CSEMinistry of Education Department of Aeronautical and Automotive Engineering Loughborough University

This paper proposes a new nonlinear composite bilateral control framework for n-degree-offreedom(n-DOF) teleoperation systems with external disturbances. Different with the existing methods which usually regard the dynamics of the master and slave robots as linear impedance models, the proposed control framework fully considers the nonlinear dynamics of the n-DOF teleoperation systems. Central to the proposed framework is the utilization of nonlinear disturbance observers for estimating the disturbances in master and slave robot systems. The nonlinear composite bilateral controller is constructed by incorporating the disturbance estimations into the nonlinear feedback linearization controller. The proposed control method guarantees satisfactory position tracking performance and desired remote force haptic simultaneously for the n-DOF teleoperation systems with external disturbances. The effectiveness of the proposed control framework is validated by its applications on 2-DOF teleoperation systems.

关键词： teleoperation system nonlinear bilateral control remote force haptic disturbance rejection nonlinear disturbance observer

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Wavefronts of a Nonlocal State-dependent Time Delay Model

引用

Acta Mathematica Sinica,English Series 2020年第1期36卷 77-92页

作者： rui jun XIE rong YUAN Zhi Hui yang School of Statistics and Applied Mathematics Anhui University of Finance and EconomicsBengbu 233030P.R.China School of Mathematical Sciences Beijing Normal UniversityBeijing 100875P.R.China

This paper is concerned with the travelling wavefronts of a nonlocal dispersal cooperation model with harvesting and state-dependent delay,which is assumed to be an increasing function of the population density with lower and upper ***,state-dependent delay is introduced into a nonlocal reaction-diffusion *** conditions of Schauder's fixed point theorem are proved by constructing a reasonable set of functionsΓ(see Section 2)and a pair of upper-lower solutions,so the existence of traveling wavefronts is *** present study is continuation of a previous work that highlights the Laplacian diffusion.

关键词： Nonlocality state-dependent delay cooperation traveling wavefronts

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

recent Advances in Deciphering the Mechanisms and Biological Functions of DNA Demethylation

引用

Chinese Journal of Chemistry 2024年第6期42卷 645-651页

作者： yang Feng Sheng-jun Chen Bi-Feng Yuan Key Laboratory of Aquatic Product Processing Ministry of Agriculture and Rural AffairsNational R&D Center for Aquatic Product ProcessingSouth China Sea Fisheries Research InstituteChinese Academy of Fishery SciencesGuangzhouGuangdong510300 China School of Public Health Research Center of Public HealthRenmin Hospital of Wuhan UniversityWuhan UniversityWuhanHubei430071 China

5-Methylcytosine (5mC) is a dynamic and reversible epigenetic modification in genomic DNA of higher *** has been well-established that the demethylation of 5mC occurs through the ten-eleven translocation (TET)-mediated oxidation of 5mC followed by thymine DNA glycosylase (TDG)-initiated base excision repair (BEr).recent findings also have identified an alternative pathway of DNA *** this pathway,TET enzymes directly oxidize 5mC to form 5-formylcytosine (5fC) or 5-carboxylcytosine (5caC).These modified bases can undergo direct deformylation or decarboxylation,***,DNA demethylation can also occur through the deamination of 5mC and 5hmC,resulting in the production of thymine and 5-hydroxymethyluracil (5hmU),*** DNA demethylation pathways possess critical functional implications and roles in biological *** recent Advances article will focus on the studies of mechanisms and biological functions of DNA demethylation,shedding light on the reversible nature of the epigenetic modification of 5mC.

关键词： Epigenetics DNA DNA methylation 5-Methylcytosine Demethylation Mechanisms Biological functions C—C bond cleavage Mass spectrometry

来源：

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

Compressed Data Separation via ℓ_(q)-Split Analysis with ℓ_(∞)-Constraint

引用

Acta Mathematica Sinica,English Series 2024年第7期40卷 1655-1673页

作者： Ming yang Gu Song Li jun Hong Lin School of Mathematical Science Zhejiang UniversityHangzhou310027P.R.China Center for Data Science Zhejiang UniversityHangzhou310027P.R.China

In this paper,we study compressed data separation(CDS)problem,i.e.,sparse data separation from a few linear random *** propose the nonconvex ℓ_(q)-split analysis with ℓ_(∞)-constraint and 0rithm ℓ_(q)-split-analysis Dantzig selector(ℓ_(q)-split-analysis DS).We show that the two distinct subcomponents that are approximately sparse in terms of two different dictionaries could be stably approximated via the ℓ_(q)-split-analysis DS,provided that the measurement matrix satisfies either a classical D-rIP(restricted Isometry Property with respect to Dictionaries and ℓ_(2) norm)or a relatively new(D,q)-rIP(rIP with respect to Dictionaries and ℓ_(q)-quasi norm)condition and the two different dictionaries satisfy a mutual coherence condition between *** the Gaussian random measurements,the measurement number needed for the(D,q)-rIP condition is far less than those needed for the D-rIP condition and the(D,1)-rIP condition when q is small enough.

关键词： Data separation ℓ_(q)-split analysis Dantzig selector frames restricted isometry property compressed sensing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Driving Environment Uncertainty-Aware Motion Planning for Autonomous Vehicles

引用

Chinese Journal of Mechanical Engineering 2022年第5期35卷 301-314页

作者： Xiaolin Tang Kai yang Hong Wang Wenhao Yu Xin yang Teng Liu jun Li College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China Tsinghua Intelligent Vehicle Design and Safety research Institute Tsinghua UniversityBeijing 100084China

Autonomous vehicles require safe motion planning in uncertain environments,which are largely caused by surrounding *** this paper,a driving environment uncertainty-aware motion planning framework is proposed to lower the risk of position uncertainty of surrounding vehicles with considering the risk of ***,a 4-degree of freedom vehicle dynamics model,and a rollover risk index are ***,the uncertainty of surrounding vehicles’position is processed and propagated based on the Extended Kalman Filter ***,the uncertainty potential field is established to handle the position uncertainty of autonomous *** addition,the model predictive controller is designed as the motion planning framework which accounts for the rollover risk,the position uncertainty of the surrounding vehicles,and vehicle dynamic constraints of autonomous ***,two edge cases,the cut-in scenario,and merging scenario are ***,the safety,effectiveness,and real-time performance of the proposed motion planning framework are demonstrated by employing a hardware-in-the-loop experiment bench.

关键词： Position uncertainty rollover prevention Autonomous vehicles Motion planning Model predictive control

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：