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Critical slope gradient for compulsory abandonment of farmland on the hilly Loess Plateau

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chinese Science Bulletin 1998年第5期43卷 409-412页

作者： TANG keli+1, zhang keli 1,2.and lei Aling 1,3 1. institute of Soil and Water Conservation, chinese Academy of sciences, yangling 712.00, china 2. Department of Hydraulic engineering, Tsinghua University, beijing 100084, china 3. Water Resources C institute of Soil and Water Conservation Chinese Academy of Sciences Yangling China Department of Hydraulic engineering Tsinghua University Beijing China Water Resources Conservation Bureau of yangtze River Ministry of Water Resources Wuhan China

Scientific evidence for the upper limit of farmland is proposed. Shallow gully erosion is one of erosion types distributed extensively on sloping farmland in the hilly regions of the Loess Plateau. Field observation and aerial photos interpretation, as well as laboratory experiments show that the shallow gully erosion occurring on the steeper farmland in the hilly regions of the Loess Plateau is an important factor leading to intensive erosion on slope, because of its extensive distribution and intensive runoff collection. The data on the formation, development and distribution of shallow gullies on sloping farmland indicate that critical slope gradient for shallow gully initiation ranges from 15 to 2. degrees with an average of 18.2.degrees. Therefore, it is suggested that critical slope gradient for compulsory abandonment of farmland on the hilly Loess Plateau should be kept within the critical slope gradient for shallow gully initiation to prevent shallow gully formation in order to control soil loss more effectively. But as the first step, the cultivation on the slopes with slope larger than 2. degrees where the maximum erosion occurs should be strictly forbidden.

关键词： hilly region of Loess Plateau upper limitation for farmland shallow gully erosion erosion dynamic.

Heteroatom doping regulates the catalytic performance of singleatom catalyst supported on graphene for ORR

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Nano Research 2024年第3期17卷 1086-1093页

作者： Ji-Kai Sun Yu-Wei Pan Meng-Qian xu lei Sun Shaolong {2. Wei-Qiao Deng Dong Zhai institute of Molecular sciences and {2. Institute of Frontier and Interdisciplinary ScienceShandong UniversityQingdao 266237China College of Chemistry and Environmental engineering Shenzhen UniversityShenzhen 518060China

Replacing fossil fuels with fuel cells is a feasible way to reduce global energy shortages and environmental ***,the oxygen reduction reaction(ORR)at the cathode has sluggish kinetics,which limits the development of fuel *** is significant to develop catalysts with high catalytic activity of *** single-atom catalysts(SACs)of Pt supported on heteroatom-doped graphene are potential candidates for *** we studied the SACs of Pt with different heteroatoms doping and screened out Pt-C_(4) and Pt-C_(3)O_(1) structures with only 0.13 V overpotential for ***,it is found that B atoms doping could weaken the adsorption capacity of Pt,while N or O atoms doping could enhance *** regularity was verified on Fe *** the electronic interaction analysis between Pt and adsorbate,we explained the mechanism of this regularity and further proposed a new descriptor named corrected d-band center(ε_(d-corr))to describe *** descriptor is an appropriate reflection of the number of free electrons of the SACs,which could evaluate its adsorption *** work provides a purposeful regulatory strategy for the design of ORR catalysts.

关键词： single-atom catalyst(SAC) oxygen reduction reaction(ORR) heteroatom doping corrected d-band center descriptor

Scale effects of leaf area index inversion based on environmental and disaster monitoring satellite data

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Science china Earth sciences 2010年第S1期53卷 92-98页

作者： zhang Hao1,LI XiaoWen1,2.CAO ChunXiang1,yang Hua2.GAO Meng{2.1,3,ZHENG Sheng1,3,{2. Min1,3,XIE DongHui2.JIA HuiCong1,JI Wei1,ZHAO Jian1,3,CHEN Wei1,3 & NI XiLiang1,3 1 State key Laboratory of Remote Sensing Science,Jointly Sponsored by institute of Remote Sensing Applications,chinese Academy of sciences and beijing Normal University,beijing 100101,china 2.State key Laboratory of Remote Sensing Science,Jointly Sponsored by beijing Normal University and institute of Remote Sensing Applications of chinese Academy of sciences,beijing 100875,china 3 Graduate University of chinese Academy of sciences,beijing 100049,china 1. State key Laboratory of Remote Sensing Science Jointly Sponsored by Institute of Remote Sensing Applications Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China2. State Key Laboratory of Remote Sensing Science Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications of Chinese Academy of Sciences Beijing 100875 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China

The spatial distribution of sub-pixel components has an impact on retrieval accuracy,and should be accounted for when inverting a three-dimensional adiative transfer model to retrieve leaf area index(LAI).To investigate this effect,we constructed three realistic scenarios with the same LAI values and other properties,except that the simulated plants had different *** implemented the radiosity method to subsequently produce synthetic bidirectional reflectance factor(BRF) datasets based upon these simulated *** inversion was conducted using these data,which showed that spatial distribution affects retrieval *** inversion was also conducted for LAI based on charge-coupled device(CCD) data from the Environment and Disaster Monitor Satellite(HJ-1),which depicted both forest and drought-resistant crop land *** showed that heterogeneity in coarse-resolution remote sensing data is the main error source in LAI *** spatial distribution of global fractal dimension index,which can be used to describe the area of sub-pixel components and their spatial distribution modes,shows good consistency with the coarse resolution LAI inversion error.

关键词： HJ-1 leaf area index scale effect spatial distribution

Formation of super-concentrated hydrochloric acid in the third phase in tertiary amine N2.5-PtCl_6^(2.)-HCl system and its influences on the Pt microemulsion extraction

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Science china Chemistry 2009年第11期52卷 1825-1834页

作者： HUANG Kun1,CHEN Jing1,zhang ChengFeng1,2.LI ZhiHong3,PAN QingHua1,SUN Yan1,LIU Shaoxuan1,LIU xueXin2.LI WeiHong1,yang ZhanLan1,WENG ShiFu1,HU TianDou3,xu YiZhuang1 & WU JinGuang1 1 College of Chemistry and Molecular engineering,Peking University,beijing 100871,china 2.institute of Chemistry,chinese Academy of sciences,beijing 100190,china 3 institute of High Energy Physics,chinese Academy of sciences,beijing 100049,china 1. College of Chemistry and Molecular engineering Peking University Beijing 100871 China 2. institute of Chemistry Chinese Academy of Sciences Beijing 100190 China 3. institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

In this paper,we have investigated the formation of the third-phase in tertiary amine(N2.5)-PtCl62.-HCl system and the microscopic phase structural evolution of platinum-loaded organic phases before and after the occurrence of the *** third-phase is characterized by various spectroscopic techniques,and the small angle X-ray scattering(SAXS) experiments demonstrate the appearance of nano-aggregates,i.e.,water-in-oil reversed micelles,in the third *** experimental results indicate that(1) formation of the third phase is related to the aggregation behaviors of nano-reversed micelles in which a super-concentrated hydrochloric acid formed with the H+ to H2. molar ratio being much higher than that of the conventional 37 wt% saturated hydrochloric acid.(2. The occurrence of the super-concentrated HCl results in a great amount of H+ and Cl-ions enriched and confined within the nano-water pools of W/O reversed micelles in third ***,the coordination behaviors of platinum complex ions in that super-concentrated hydrochloric acid are very different from their corresponding behaviors in bulk aqueous *** is possible that H+ ions participate in the formation of such complexes as HmPtCl6z+ in the super-concentrated hydrochloric acid.(3) The relative contents of various HmPtCl6z+ complexes are different corresponding to the H+ ion concentrations in confined nanowater *** association ability of the acidified tertiary amine N2.5 molecules(R3NH+) with various HmPtCl6z+ complexes plays an important role in affecting the platinum extraction behaviors.

关键词： solvent extraction third phase super-concentrated hydrochloric acid tertiary amine platinum

Intelligent Recognition Using Ultralight Multifunctional Nano‑Layered Carbon Aerogel Sensors with Human‑Like Tactile Perception

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Nano-Micro Letters 2024年第1期16卷 172-186页

作者： Huiqi Zhao Yizheng zhang lei Han Weiqi Qian Jiabin Wang Heting Wu Jingchen Li Yuan Dai Zhengyou zhang Chris RBowen Ya yang CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro‑Nano Energy and SensorBeijing Institute of Nanoenergy and NanosystemsChinese Academy of SciencesBeijing 101400People’s Republic of China Tencent Robotics X Shenzhen 518054People’s Republic of China School of Nanoscience and Technology University of Chinese Academy of SciencesBeijing 100049People’s Republic of China Department of Mechanical engineering University of BathBath BA27AKUK Center on Nanoenergy Research School of Physical Science and TechnologyGuangxi UniversityNanning 530004People’s Republic of China

Humans can perceive our complex world through multi-sensory *** limited visual conditions,people can sense a variety of tactile signals to identify objects accurately and ***,replicating this unique capability in robots remains a significant ***,we present a new form of ultralight multifunctional tactile nano-layered carbon aerogel sensor that provides pressure,temperature,material recognition and 3D location capabilities,which is combined with multimodal supervised learning algorithms for object *** sensor exhibits human-like pressure(0.04–100 kPa)and temperature(2..5–66.2.)detection,millisecond response times(11 ms),a pressure sensitivity of 92.2. kPa^(−1)and triboelectric durability of over 6000 *** devised algorithm has universality and can accommodate a range of application *** tactile system can identify common foods in a kitchen scene with 94.63%accuracy and explore the topographic and geomorphic features of a Mars scene with 100%*** sensing approach empowers robots with versatile tactile perception to advance future society toward heightened sensing,recognition and intelligence.

关键词： Multifunctional sensor Tactile perception Multimodal machine learning algorithms Universal tactile system Intelligent object recognition

Numerical study on local scour characteristics around submarine pipelines in the Yellow River Delta silty sandy soil under waves and currents

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Deep Underground Science and engineering 2024年第2期3卷 182-196页

作者： Peng Yu Ruigeng Hu Jike zhang Qi {2. Jieru Zhao lei Cao Chenghao Zhu key Laboratory of Geological Safety of Coastal Urban Underground Space Ministry of Natural ResourcesQingdaoChina Qingdao Geo-engineering Surveying institute(Qingdao Geological Exploration Development Bureau) QingdaoChina Sinopec Petroleum engineering Corporation DongyingChina State key Laboratory of Hydroscience and engineering Tsinghua UniversityBeijingChina Department Civil and Environmental engineering Politecnico di MilanoMilanItaly College of Environmental Science and engineering Ocean University of ChinaQingdaoChina

Due to their high reliability and cost-efficiency,submarine pipelines are widely used in offshore oil and gas resource *** to the interaction of waves,currents,seabed,and pipeline structures,the soil around submarine pipelines is prone to local scour,severely affecting their operational *** the Yellow River Delta as the research area and based on the renormalized group(RNG)k-εturbulence model and Stokes fifth-order wave theory,this study solves the Navier-Stokes(N-S)equation using the finite difference *** volume of fluid(VOF)method is used to describe the fluid-free surface,and a threedimensional numerical model of currents and waves-submarine pipeline-silty sandy seabed is *** rationality of the numerical model is verified using a self-built waveflow *** this basis,in this study,the local scour development and characteristics of submarine pipelines in the Yellow River Delta silty sandy seabed in the prototype environment are explored and the influence of the presence of pipelines on hydrodynamic features such as surrounding flow field,shear stress,and turbulence intensity is *** results indicate that(1)local scour around submarine pipelines can be divided into three stages:rapid scour,slow scour,and stable *** maximum scour depth occurs directly below the pipeline,and the shape of the scour pits is asymmetric.(2.As the water depth decreases and the pipeline suspension height increases,the scour becomes more intense.(3)When currents go through a pipeline,a clear stagnation point is formed in front of the pipeline,and the flow velocity is positively correlated with the depth of *** study can provide a valuable reference for the protection of submarine pipelines in this area.

关键词： local scour numerical simulation submarine pipelines Yellow River Delta

Unsaturated bi-heterometal clusters in metal-vacancy sites of 2. MoS2.for efficient hydrogen evolution

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Carbon Energy 2024年第3期6卷 264-275页

作者： Gonglei Shao Jie xu Shasha Gao {2. {2. Song Liu xu {2. Zhen Zhou Interdisciplinary Research Center for Sustainable Energy Science and engineering(IRC4SE2. School of Chemical EngineeringZhengzhou UniversityZhengzhouHenanChina College of Chemistry and Materials engineering Wenzhou UniversityWenzhouZhejiangChina key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) College of ChemistryNankai UniversityTianjinChina State key Laboratory of Chemo/Biosensing and Chemometrics Institute of Chemical Biology and Nanomedicine(ICBN)College of Chemistry and Chemical EngineeringHunan UniversityChangshaHunanChina institute of New Energy Material Chemistry School of Materials Science and EngineeringNankai UniversityTianjinChina

The valence states and coordination structures of doped heterometal atoms in two-dimensional(2.)nanomaterials lack predictable regulation ***,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2. molybdenum *** unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active *** them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical ***,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2. atomic lattice but not limited to 2. nanomaterials.

关键词： clusters hydrogen evolution reaction metal vacancy MoS2 unsaturated heterometal

Tunable quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures

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National Science Review 2024年第3期11卷 100-107页

作者： Feng xue Yusheng Hou Zhe Wang Zhiming xu {2. He Ruqian Wu Yong xu Wenhui Duan beijing Academy of Quantum Information sciences State key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Guangdong Provincial key Laboratory of Magnetoelectric Physics and Devices Center for Neutron Science and Technology School of Physics Sun Yat-sen University State key Laboratory of Surface Physics Key Laboratory of Computational Physical Sciences and Department of PhysicsFudan University Frontier Science Center for Quantum Information Department of Physics and Astronomy University of California-Irvine Tencent Quantum Laboratory Tencent Technology(Shenzhen)Co.Ltd RIkeN Center for Emergent Matter Science(CEMS) institute for Advanced Study Tsinghua University

The quantum anomalous Hall effect（QAHE） has unique advantages in topotronic applications, but it is still challenging to realize the QAHE with tunable magnetic and topological properties for building functional devices. Through systematic first-principles calculations, we predict that the in-plane magnetization induced QAHE with Chern numbers C = ±1 and the out-of-plane magnetization induced QAHE with high Chern numbers C = ±3 can be realized in a single material candidate, which is composed of van der Waals（vdW）coupled Bi and MnBi2.e4monolayers. The switching between different phases of QAHE can be controlled in multiple ways, such as applying strain or（weak） magnetic field or twisting the vdW materials. The prediction of an experimentally available material system hosting robust, highly tunable QAHE will stimulate great research interest in the field. Our work opens a new avenue for the realization of tunable QAHE and provides a practical material platform for the development of topological electronics.

关键词： quantum anomalous Hall effect topological quantum phase transition van der Waals heterostructures tunable Chern number high Chern number

MODIFIED STOCHASTIC EXTRAGRADIENT METHODS FOR STOCHASTIC VARIATIONAL INEQUALITY

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Journal of Computational Mathematics 2024年第2期42卷 390-414页

作者： Ling zhang Lingling xu School of Management and Economic Beijing Institute of TechnologyBeijing 100081China School of Mathematical sciences Nanjing Normal UniversityNanjing 210023China School of Mathematical sciences and Jiangsu key Laboratory for NSLSCS Nanjing Normal UniversityNanjing 210023China

In this paper,we consider two kinds of extragradient methods to solve the pseudo-monotone stochastic variational inequality ***,we present the modified stochastic extragradient method with constant step-size(MSEGMC)and prove the convergence of *** the strong pseudo-monotone operator and the exponentially growing sample sequences,we establish the R-linear convergence rate in terms of the mean natural residual and the oracle complexity O(1/ǫ).Second,we propose a modified stochastic extragradient method with adaptive step-size(MSEGMA).In addition,the step-size of MSEGMA does not depend on the Lipschitz constant and without any line-search ***,we use some numerical experiments to verify the effectiveness of the two algorithms.

关键词： Stochastic variational inequality Pseudo-monotone Modified stochastic ex-tragradient methods Adaptive step-size