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On the positivity of high-degree Schur classes of an ample vector bundle

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Science China Mathematics 2022年第1期65卷 51-62页

作者： jian xiao Department of Mathematical Sciences and Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China

Let X be a smooth projective variety of dimension n,and let E be an ample vector bundle over *** show that any Schur class of E,lying in the cohomology group of bidegree(n-1,n-1),has a representative which is strictly positive in the sense of smooth *** conforms the prediction of Griffiths conjecture on the positive polynomials of Chern classes/forms of an ample vector bundle on the form level,and thus strengthens the celebrated positivity results of Fulton and Lazarsfeld(1983)for certain degrees.

关键词： ample vector bundles Griffiths conjecture positive polynomials Schur classes

The Survival Analysis of a Non-autonomous N-dimensional Volterra Mutualistic System in a Polluted Environment

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Acta Mathematicae Applicatae Sinica 2007年第1期23卷 133-140页

作者： xiao-jian Li Ke Wang Department of Mathematics Northeast Normal University Changchun 130024 China Department of Mathematics Harbin Institute of Technology Weihai 264209 China

In this paper, we extend the autonomous n-Dimensional Volterra Mutualistic System to a non- autonomous system. The condition of persistence and extinction is obtained for each population, and the threshold is establis... 详细信息

关键词： Pollution persistence extinction comparison theorem threshold

Synthesis and properties of novel cationic gemini surfactants with adamantane spacer

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Chinese Chemical Letters 2014年第2期25卷 367-369页

作者： xiao-jian Xu jian-Wei Guo Xing Zhong School of Chemical Engineering and Light Industry Guangdong University of Technology

Novel quaternary ammonium cationic gemini surfactants, with two hydrocarbon chains and an adamantane core, were designed and synthesized by three-step reactions from adamantane. The structure of obtained surfactants were confirmed by 1H NMR, FTIR and elements analysis and the surface properties of these surfactants were also studied by surface tension measurements. These target surfactants exhibit much lower critical micelle concentrations （CMC） and higher efficiency in lowering the surface tension of water than typical surfactants.

关键词： Gemini surfactants Adamantane Synthesis

China＇s nuclear power under the global 1.5℃ target： Preliminary feasibility study and prospects

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Advances in Climate Change Research 2018年第2期9卷 138-143页

作者： xiao Xin-jian jianG Ke-Jun Energy Research Institute National Development and Reform Commission Beijing 100038 China

This study explores the measures to achieve the global 1.5 ℃ temperature rise target （1.5 ℃ target） by analyzing the feasibility and obstacles of nuclear power in China. The 1.5 ℃target imposes stricter requirements on China＇s nuclear power. Considering the available nuclear power plant sites, nuclear power layout, equipment manufacture ＆ supply, nuclear power plant construction capacity, supportive operation ＆ management talents, investment, cost effectiveness, and public acceptance, the achievement of the development objectives of nuclear power in China considering the 1.5 ℃ Target is difficult. However, it is possible if favorable decisions and policies are made.

关键词： 1.5 ℃ target Nuclear power in China Solutions Feasibility Decision-making

Bounding the sum of powers of the Laplacian eigenvaluesof graphs

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Applied Mathematics(A Journal of Chinese Universities) 2011年第2期26卷 142-150页

作者： CHEN xiao-dan QIAN jian-guo School of Mathematical Sciences Xiamen University Xiamen 361005 Fujian P.R. China

For a non-zero real number α, let sα（G） denote the sum of the αth power of thenon-zero Laplacian eigenvalues of a graph G. In this paper, we establish a connection betweensα（G） and the first Zagreb index in which the H¨older’s inequality plays a key role. By usingthis result, we present a lot of bounds of sα（G） for a connected （molecular） graph G in terms ofits number of vertices （atoms） and edges （bonds）. We also present other two bounds for sα（G）in terms of connectivity and chromatic number respectively, which generalize those results ofZhou and Trinajsti′c for the Kirchho？ index [B Zhou, N Trinajsti′c. A note on Kirchho？ index,Chem. Phys. Lett., 2008, 455： 120-123].

关键词： Laplacian eigenvalues the first Zagreb index Kirchhoff index connectivity chromatic number.

Self-supported transition metal phosphide based electrodes as high-efficient water splitting cathodes

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Frontiers of Chemical Science and Engineering 2018年第3期12卷 494-508页

作者： Yan Zhang jian xiao Qiying Lv Shuai Wang State Key Laboratory of Digital Manufacturing Equipment and Technology Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education) School of Chemistry and Chemical Engineering Huazhong University of Science and Technology Wuhan 430074 China Flexible Electronics Research Center (FERC) School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

Electrolytic water splitting has been considered as a promising technology to produce highly pure H2 by using electrical power produced from wind, solar energy or other fitful renewable energy resources. Combining novel self-supporting structure and high-performance transition metal phosphides （TMP） shows substantial promise for practical application in water splitting. In this review, we try to provide a comprehensive analysis of the design and fabrication of various self-supported TMP electrodes for hydrogen evolution reaction, which are divided into three categories： catalysts growing on carbon-based substrates, catalysts growing on metal-based substrates and free- standing catalyst films. The material structures together with catalytic performances of self-supported electrodes are presented and discussed. We also show the specific strategies to further improve the catalytic performance by elemental doping or incorporation of nanocarbons. The simple and one-step methods to fabricate self-supported TMP electrodes are also highlighted. Finally, the chal- lenges and perspectives for self-supported TMP electrodes in water splitting application are briefly discussed.

关键词： transition metal phosphide self-supported electrode electrocatalysis hydrogen evolution reaction

Decentralized Adaptive Strategies for Synchronization of Fractional-order Complex Networks

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IEEE/CAA Journal of Automatica Sinica 2017年第3期4卷 543-550页

作者： Quan Xu Shengxian Zhuang Yingfeng Zeng jian xiao School of Electrical Engineering Southwest Jiaotong University School of Technology Xihua University

This paper focuses on synchronization of fractionalorder complex dynamical networks with decentralized adaptive *** on local information among neighboring nodes,two fractional-order decentralized adaptive strategies are designed to tune all or only a small fraction of the coupling gains *** constructing quadratic Lyapunov functions and utilizing fractional inequality techniques,Mittag-Leffler function,and Laplace transform,two sufficient conditions are derived for reaching network synchronization by using the proposed adaptive ***,two numerical examples are given to verify the theoretical results.

关键词： Decentralized adaptive control fractional-order complex networks quadratic Lyapunov functions synchronization

Numerical stabilities of loosely coupled methods for robust modeling of lightweight and flexible structures in incompressible and viscous flows

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Acta Mechanica Sinica 2017年第4期33卷 709-724页

作者： Deniz Tolga Akcabay jian xiao Yin Lu Young Department of Naval Architecture and Marine Engineering University of Michigan 2600 Draper Dr. Ann ArborMI 48109-2145 USA

The growing interest to examine the hydroelastic dynamics and stabilities of lightweight and flexible materials requires robust and accurate fluid–structure interaction（FSI）models. Classically, partitioned fluid and structure solvers are easier to implement compared to monolithic methods;however, partitioned FSI models are vulnerable to numerical（“virtual added mass”） instabilities for cases when the solid to fluid density ratio is low and if the flow is *** a partitioned method, the loosely hybrid coupled（LHC）method, which was introduced and validated in Young et al.（Acta Mech. Sin. 28：1030–1041, 2012）, has been successfully used to efficiently and stably model lightweight and flexible structures. The LHC method achieves its numerical stability by, in addition to the viscous fluid forces, embedding potential flow approximations of the fluid induced forces to transform the partitioned FSI model into a semi-implicit scheme. The objective of this work is to derive and validate the numerical stability boundary of the LHC. The results show that the stability boundary of the LHC is much wider than traditional loosely coupled methods for a variety of numerical integration schemes. The results also show that inclusion of an estimate of the fluid inertial forces is the most critical to ensure the numerical stability when solving for fluid–structure interaction problems involving cases with a solid to fluid-added mass ratio less than one.

关键词： incompressible viscous lightweight partitioned validated discretization solver embedding stably Reynolds

DVB-S2 inner receiver design for broadcasting mode

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第1期8卷 28-35页

作者： YANG jian-xiao WANG Kuang ZOU Zhi-yong Institute of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China Guoxin Co Ltd Hangzhou 310027 China

This paper details on the design of DVB-S2 receivers which is compliant with the broadcasting mode. Special at-tention is paid to the specific receiver functions necessary to demodulate the received signal. To show the system performance we consider the design of a complete receiver consisting of timing recovery unit, frame synchronization unit, frequency recovery unit and phase recovery unit. The system is easier to hardware implementation comparing with that provided in (ETSI, 2005; Sun et al., 2004). After the performance of the algorithms is analyzed and a quantitative result is given, this allows us to draw conclusions concerning the achievable system performance under realistic complexity assumptions.

关键词： DVB-S2 Timing recovery Frame synchronization Frequency recovery Phase recovery