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Pythagorean Theorem & Curvature with Lower or Upper Bound

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Chinese Annals of Mathematics,Series B 2022年第1期43卷 95-114页

作者： Xiaole SU Hongwei SUN yusheng wang School of Mathematical Sciences(and Lab.math.Com.Sys.) Beijing Normal UniversityBeijing100875China School of Mathematics Science Capital Normal UniversityBeijing100037China

In this paper,the authors give a comparison version of Pythagorean theo-rem to judge the lower or upper bound of the curvature of Alexandrov spaces(including Riemannian manifolds).

关键词： Pythagorean theorem Alexandrov space Toponogov's theorem

Quasi-convex subsets in Alexandrov spaces with lower curvature bound

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Frontiers of Mathematics in China 2022年第6期17卷 1063-1082页

作者： Xiaole SU HIongwei SUN yusheng wang School of Mathematical Sciences(and Key Laboratory Mathematics and Complex Systems Ministry of EducationChina)Beijing Normal UniversityBeijing100875China School of Mathematics Sciences Capital Normal UniversityBeijing100037China

We introduce quasi-convex subsets in Alexandrov spaces with lower curvature bound,which include not only all closed convex subsets without boundary but also all extremal ***,we explore several essential properties of such kind of subsets including a generalized Liberman *** turns out that the quasi-convex subset is a nice and fundamental concept to illustrate the similarities and differences between Riemannian manifolds and Alexandrov spaces with lower curvature bound.

关键词： Quasi-convex subset Alexandrov space extremal subset quasigeodesic

An isometrical CP^n-theorem

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Frontiers of Mathematics in China 2018年第2期13卷 367-398页

作者： Xiaole SU Hongwei SUN yusheng wang School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems (Beijing Normal University) Ministry of Education Beijing 100875 China School of Mathematical Sciences Capital Normal University Beijing 100037 China

et Mn （n ≥ 3） be a complete Riemannian manifold with secM ≥ 1, and let Mni^ni （i = 1, 2） be two complete totally geodesic submanifolds in M. We prove that if n1 ＋ n2 = n - 2 and if the distance ｜M1M2｜≥π/2, then Mi is isometric to s^ni/Zh, CP^m/2, or CP^ni/2/Z2 with the canonical metric when ni 〉 0, and thus, M is isometric to Sn/Zh, CPn/2, or CPn/2/Z2 except possibly iso when n = 3 and M1 （or M2） ≌ S1/Zh with h ≥ 2 or n iso= 4 and M1 （or M2） iso ≌ RP^2

关键词： Rigidity positive sectional curvature totally geodesic submanifolds

Enhancing interaction performance of soft pneumatic-networks grippers by skeleton topology optimization

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Science China(Technological Sciences) 2021年第12期64卷 2709-2717页

作者： CHEN ShiTong wang yusheng LI DeChen CHEN FeiFei ZHU XiangYang Robotics Institute School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

The inherent compliance of soft materials imbues robots,generally referred to as soft robots,with particular advantages in producing adaptive and safe ***,the mainstream design paradigms of soft robots have been focused on pursuing large free motions only,usually at the expense of greatly decreased stiffness,leading to limited capability of withstanding external loads in interactive *** is a pressing need to incorporate the interaction specifications at the design stage to embody soft robots with not only proper deformability but equally importantly,considerable stiffness to perform complex tasks in practical ***,inspired by the dexterity of human hands,we propose a computational design framework for soft grippers with a focus on improving their interaction performance in power grasping or precision grasping *** design paradigm rests on attaching a relatively stiffer skeleton layer to the parametric pneumatic networks based actuator which is widely used due to the geometric advantage,and the skeleton layout is designed for customized interaction conditions by a level set based topology optimization *** expected,the optimized skeleton layouts exhibit specified structural features highly relevant to the predefined concentrated loads for precision grip or distributed loads for power grip,which physically implies the compromise between deformability and *** the interaction forces are difficult to measure in situ,we devise power and precision grasping scenarios and evaluate the critical actuation pressure of the object’s falling *** experiments qualitatively demonstrate the superiority of each specified *** work represents an initial step toward the rational design for interaction in soft robots.

关键词： soft robotics interaction grippers topology optimization

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Archean Basement and a Paleoproterozoic Collision Orogen in the Huoqiu Area at the Southeastern Margin of North China Craton: Evidence from Sensitive High Resolution Ion Micro-Probe U-Pb Zircon Geochronology

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Acta Geologica Sinica(English Edition) 2010年第1期84卷 91-104页

作者： WAN yusheng DONG Chunyan wang Wei XIE Hangqiang LIU Dunyi Beijing SHRIMP Center Institute of Geology Chinese Academy of Geological Sciences Beijing 10037 China

This paper reports sensitive high resolution ion micro-probe U-Pb zircon ages for the ＂Huoqiu Group＂ and granitoids of the Early Precambrian basement in the Huoqiu area, southeastern margin of the North China Craton. The ＂Huoqiu Group＂ is similar in rock association and metamorphism to the khondalite series, apart from it containing considerable amounts of banded iron formation. All detrital zircons from the ＂Huoqiu Group＂ meta-sedimentary rocks are 3.0 Ga and 2.75 Ga, without any 2.5 Ga and younger ones, as is commonly found in Paleoproterozoic khondalite series in other areas of the North China Craton. In the Huoqiu area, 2.75 Ga and 2.56 Ga granitoids have also been identified. This basement assemblage underwent strong metamorphism during the late Paleoproterozoic （-1.84 Ga） tectonothermal event that is widely developed in the North China Craton. Thus the formation time of the ＂Huoqiu Group＂ can be constrained between 2.75 and 1.84 Ga in terms of detrital and metamorphic zircon ages. It is considered, combined with regional data, that there may be a Paleoproterozoic collision orogen extending in a NWW-SEE direction to the southern margin of the North China Craton.

关键词： khondalite series trondhjemite-tonalite-granodiorite sensitive high resolution ion micro-probe U-Pb dating Archean Paleoproterozoic collision orogen North China Craton

Flexible and stable 3D lithium metal anodes based on self-standing MXene/COF frameworks for high-performance lithium-sulfur batteries

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Nano Research 2021年第10期14卷 3576-3584页

作者： Chuanliang Wei yusheng wang Yuchan Zhang Liwen Tan Yi Qian Yuan Tao Shenglin Xiong Jinkui Feng Research Center for Carbon Nanomaterials Key Laboratory for Liquid-Solid Structural Evolution&Processing of Materials(Ministry ofEducation)School of Materials Science and EngineeringShandong UniversityJinan 250061China School of Chemistry and Chemical Engineering Shandong UniversityJinan 250100China

Lithium metal(Li)is believed to be the ultimate anode for lithium-ion batteries(LIBs)owing to the advantages of high theoretical capacity,the lowest electrochemical potential,and light ***,issues such as uncontrollable growth of Li dendrites,large volume changes,high chemical reactivity,and unstable solid electrolyte interphase(SEI)hinder its rapid development and practical *** a stable and dendrite-free Li-metal anode is obtained by designing a flexible and freestanding MXene/COF framework for metallic ***-LZU1 microspheres are distributed among the MXene film *** COF-LZU1 microspheres as nucleation seeds can promote uniform Li nucleation by homogenizing the Li^(+)flux and lowering the nucleation barrier,finally resulting in dense and dendrite-free Li *** the regulation of the COF-LZU1 seeds,the Coulombic efficiency of the MXene/COF-LZU1 framework and electrochemical stability of corresponding symmetric cells are obviously ***-S full cells with the modified Li-metal anode and sulfurized polyacrylonitrile(S@PAN)cathode also exhibited a superior electrochemical performance.

关键词： MXene covalent organic framework(COF) dendrite-free lithium metal anode lithium sulfur battery sulfurized polyacrylonitrile

Structure-activity relationship of defective electrocatalysts for nitrogen fixation

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Chinese Chemical Letters 2023年第7期34卷 87-101页

作者： yusheng wang Nan Yang Xue Xin Yingjie Yu Yuao Wei Baoli Zha Wenjing Liu Key Laboratory of Flexible Electronics(KLOFE)&Institute of Advanced Materials(IAM) Nanjing Tech UniversityNanjing 211816China

Ammonia(NH_(3)), as an important chemical substance and clean energy carrier, plays an indispensable role in industrial and agricultural production. The electrocatalytic synthesis of NH+3 under mild conditions has attracted worldwide attention in the energy field due to its environmental friendliness and cost efficiency,but unsatisfactory NH_(3) yields and Faradaic efficiencies are restricting its development. The introduction of defect has been demonstrated as a feasible way to overcome the disadvantages of electrochemistry, as it can regulate the electronic structure and modulate coordination environment of electrocatalysts, which further create active sites and enhance nitrogen adsorption. In this regard, it is necessary to understand the effects of various types of defects on electrocatalysts based on the latest progress in the defect engineering for nitrogen reduction reaction(NRR). In this review, the concept, classifications, and characterization of defects as well as the approaches to create them in electrocatalysts are firstly ***, certain types of defects(vacancy, dopant, amorphism, edge/corner, and porousness) affecting the performances of various electrocatalysts are further described. Finally, the summary and challenges of electrocatalytic ammonia synthesis are proposed to design advanced electrocatalysts with high efficiency.

关键词： Nitrogen reduction reaction Defect Approaches to induce defects Electrochemistry

Persisting in the Strategy of“Keeping a Low Profile”and Enhancing the Awareness of“Trying to Do Something”

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China International Studies 2010年第2期30卷 66-79页

作者： wang yusheng former Ambassador of China to APEC

Since reform and opening up and in recent years in particular, China's overall national strength has been growing noticeably. The speed of China's development has attracted worldwide *** aggregate national strength is... 详细信息

关键词：综合国力改革开放发展速度金融危机中国

Panorama of China's Oil Refining Industry in 2005

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China Oil & Gas 2006年第1期13卷 50-51页

作者： wang yusheng China University of Geosciences-Beijing

China＇s oil refining industry registered a loss of about 30 billion yuan （US$3,7 billion） in 2005, a sharp contrast to the 20.8 billion yuan in profits in 2004, according to the statistical figures made available from China＇s National Development and Reform Commission （NDRC）, which is in charge of industrial policy. The development of China＇s oil refining industry has witnessed tension between oil demand and straining supply as well as a steady increase of output in 2005, impacted by domestic and international factors.

关键词： 2005年中国石油精炼工业国际发展企业改革