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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

Convergence rate of kernel canonical correlation analysis

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Science China Mathematics 2011年第10期54卷 2161-2170页

作者： CAI Jia sun hongwei School of Mathematics and Computational Science Guangdong University of Business Studies Guangzhou 510320 China School of Science University of Jinan Jinan 250022 China

Kernel canonical correlation analysis(CCA) is a nonlinear extension of CCA,which aims at extract-ing the information shared by two random variables. It has wide applications in many fields,such as information retrieval. This paper gives the convergence rate analysis of kernel CCA under some approximation conditions and some suggestions on how to choose the regularization parameter. The result shows that the convergence rate only depends on two parameters:the rate of regularization parameter and the decay rate of eigenvalues of compact operator VY X,and it gives better understanding of kernel CCA.

关键词： covariance operator canonical correlation analysis RKHS

An on-line tool path smoothing algorithm for 6R robot manipulator with geometric and dynamic constraints

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Science China(Technological Sciences) 2021年第9期64卷 1907-1919页

作者： sun hongwei YANG JiXiang LI DingWei DING Han School of Mechanical Science and Engineering State Key Laboratory of Digital Manufacturing Equipment and TechnologyHuazhong University of Science and TechnologyWuhan 430074China

The tool path smoothness of the industrial robot directly influences the dynamic performance of its motion control. Therefore, it is important to smooth the path that is composed of small linear segments, in order to achieve continuous and smooth *** paper uses the FIR filter interpolation method to generate the smooth tool tip position and tool orientation trajectory for robot manipulators with 6 rotational(6R) joints. The geometric smoothness and motion interpolation are achieved in one *** maximum velocity and acceleration of joints are constrained when calculating the time parameters of the FIR filter. By specially designing the overlapping time at transition corners, the tool tip position and tool orientation deviations are all constrained in the workpiece coordinate system. Considering the complexity of the inverse kinematics of the robot, in order to constrain the velocity and acceleration of robot joints, this paper proposes a simplified method which directly establishes the relationship between joint motion and tool motion through the derivative of joint motion to tool motion without considering the inverse kinematics. Simulation and experiment results show that the algorithm can generate continuous acceleration commands of the tool tip position and tool orientation within the corner error tolerance. The preset velocity and acceleration limitations of six joints are all constrained well. Comparisons with existing algorithms demonstrate advantages of the proposed method.

关键词： robots tool path corner smooth FIR filter kinematics

Distribution of Electrical Field Energy for Conversion of Methane to C_2 Hydrocarbons via Dissymmetrical Electric Field Enhanced Plasma

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Journal of Natural Gas Chemistry 2006年第2期15卷 115-121页

作者： Baowei Wang Genhui XU hongwei sun Key Laboratory for Green Chemical Technology School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China Research Institute of Petroleum Processing Beijing 100083 China

Direct conversion of methane into C2 hydrocarbons through alternating current electric field enhanced plasma was studied under room temperature, atmospheric pressure and low power conditions. The distribution of electrical field intensity and distribution of energy were calculated with software that was developed by us according to the charge simulation method. The results indicated that the energy of tip of electrode was 0.36 J/mm^3 and it was higher than the methane dissociation energy （0.0553 J/mm^3）. The methane located at this area can be activated easily. The higher-energy particles produced by dissociation collided with molecules around them and initiated consecutive reactions between free radicals and molecules. The method was proved to be valided and could be taken as a basis for the electrical field study concerned.

关键词： electrical field enhanced plasma intensity of electrical field distribution of energy

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

Achieving nitritation at low temperatures using free ammonia inhibition on Nitrobacter and real-time control in an SBR treating landfill leachate

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Journal of Environmental Sciences 2015年第4期27卷 157-163页

作者： hongwei sun Yongzhen Peng Shuying Wang Juan Ma Key Laboratory of Beijing Water Quality Science and Water Environment Recovery Engineering Beijing University of Technology School of Environmental and Municipal Engineering Lanzhou Jiaotong University

Free ammonia（FA） inhibition on nitrite-oxidized bacteria（NOB） and real-time control are used to achieve nitrogen removal from landfill leachate via nitrite pathway at low temperatures in sequencing batch reactor. The inhibition of FA on NOB activity during the aerobic period was prolonged using real-time control. The degree of nitrite accumulation was monitored along with variations of the ammonia-oxidizing bacteria and NOB population using fluorescence in situ hybridization techniques. It is demonstrated that the end-point of ammonia oxidization is detected from the on-line measured dissolved oxygen,oxidization–reduction potential, and p H signals, which could avoid the loss the FA inhibition on NOB caused by excess aeration. At low temperature（13.0–17.6°C）, the level of nitrite pathway rapidly increased from 19.8% to 90%, suggesting that nitritation was successfully started up at low temperature by applying syntrophic association of the FA inhibition and real-time control, and then this high level of nitrite pathway was stably maintained for as long as 233 days. Mechanism analysis shows that the establishment of nitritation was primarily the result of predominant ammonia-oxidizing bacteria developed in the nitrifying bacteria population compared to NOB. This was mainly due to a gradual reduction of nitrite amount that is available to provide energy for the growth of NOB,eventually leading to the elimination of NOB from the bacterial clusters in sequencing batch reactor sludge system.

关键词： Landfill leachate Nitritation Low temperature Free ammonia Inhibition AOB and NOB

Preparation and Rheological Properties of Vacuum Lubricating Grease

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China Petroleum Processing & Petrochemical Technology 2021年第1期23卷 120-126页

作者： He Yifeng sun hongwei Liu Xinyang SINOPEC Research Institute of Petroleum Processing Beijing 100083

A kind of vacuum lubricating grease was prepared by using perfluoropolyether as base oil,perfluorinated polymer as thickener,and self-made *** colloidal stability of the grease was greatly improved by introducing a colloidal structure *** rheological properties of the self-made grease(SMG),such as viscosity versus time,thixotropy,etc.,were studied by a rheometer at different temperatures and were compared with those of foreign brand grease(FBG).The results show that the performance of SMG reached the level of similar FBG,and some properties such as mechanical stability,colloidal stability,extreme pressure and antiwear properties were *** can be used for long life lubrication of moving parts in a vacuum environment.

关键词： vacuum lubricating grease perfluoropolyether rheology thixotropy

New Strategies for Nitrogen Fixation and Pollution Control

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Chinese Journal of Chemistry 2021年第12期39卷 3199-3210页

作者： hongwei sun Fengjiao Quan Chengliang Mao Lizhi Zhang Key Laboratory of Pesticide&Chemical Biology of Ministry of Education Institute of Environmental&Applied ChemistryCollege of ChemistryCentral China Normal UniversityWuhanHubei 430079China

In the context of sustainable development and carbon neutrality,great efforts have been dedicated to the utilization of green energy such as sunlight and renewable electricity to tackle problems encountered amid energy-and emission-intensive industries like nitrogen *** significant progress made in the photocatalytic and electrocatalytic nitrogen fixation,they are still limited by the insufficient activity due to poor N_(2) ***,we reviewed our work focusing on the rational design of active sites for the efficient photocatalytic and electrocatalytic activation of molecular N_(2),including oxygen vacancy of BiOX,plasmonic Ru and Fe on TiO_(2-x)H_(y),interfacial polarization field of single-atom Fe and strained core-shell Ru ***,this review also covers our endeavor to deal with environmental pollution based on the iron redox chemistry,including the O_(2) activation by low-valent iron species,the acceleration of iron redox cycle to improve Fenton-like reactivity,and the development of novel zero-valent iron.

关键词： Nitrogen fixation Photocatalysis Electrocatalysis Iron Environmental pollution

PHOTOACOUSTIC DEFLECTION TECHNIQUE OF PULSED LASER IN LIQUID

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Chinese Journal of Acoustics 1989年第4期8卷 325-334页

作者： Wang, Qinhua Huang, Mencai sun, hongwei Suzhou Univ China

In this paper, we give the distribution of temperature field and pulse photoacoustic pressure generated by pulsed laser in liquid. The effect of pulse duration and laser beam dimension on the pressure signal is discussed. The experimental results obtained by the Gauss laser beam deflection technique agree with the theory qualitatively. This technique provides a novel optical method for the contactless and rapid measurement of thermodynamic parameters.

关键词： Mathematical Techniques Integral Equations Temperature Distribution Thermodynamics