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On Mbius Form and Mbius Isoparametric Hypersurfaces

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Acta Mathematica Sinica,English Series 2009年第12期25卷 2077-2092页

作者： Ze jun hu Xiao Li TIAN Department of Mathematics Zhengzhou University Zhengzhou 450052 P. R. China Department of humanities and Social Sciences He 'nan Vocational and Technical College of Communications Zhengzhou 450007 P. R. China

An umbilic-free hypersurface in the unit sphere is called MSbius isoparametric if it satisfies two conditions, namely, it has vanishing MSbius form and has constant MSbius principal curvatures. In this paper, under the condition of having constant MSbius principal curvatures, we show that the hypersurface is of vanishing MSbius form if and only if its MSbius form is parallel with respect to the Levi-Civita connection of its MSbius metric. Moreover, typical examples are constructed to show that the condition of having constant MSbius principal curvatures and that of having vanishing MSbius form are independent of each other.

关键词： Mobius isoparametric hypersurface Mobius second fundamental form Mobius metric MSbius form paxallel Mobius form

Use of rural energy resources and eco-environmental degradation in Tibet

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Journal of Environmental Sciences 2004年第6期16卷 1046-1050页

作者： WEIXing-hu YANGPing WANGYa-jun XIEZhong-kui ColdandAridRegionsEnvironmentalandEngineeringResearchInstitute ChineseAcademyofSciencesLanzhou730000China.

Cattle dung, firewood, and crop straw have being used as survival necessities by farmers and herdsmen for thousands of years in Tibet. Until recently such biotic energy source still constitutes more than 92 per cent of total rural energy consumption due to lack of petroleum, coal and new alternative energy sources. As a result, environmental degradation such as land desertification, soil erosion, grassland degradation and soil fertility reduction is increasingly aggravated, the area of desertified land has increased 1467.5 km2 from 1991 to 1997. Degraded area of grassland has reached 2.60×107hm2, increased by 116.1% from 1987 to 1996. To prevent further deterioration of eco-environment in Tibet great efforts should be made to make full use of ample solar energy, wind energy and other biotic energy of the Qinghai-Tibet Plateau. The solar cooking stoves and solar hothouse, expand forest area and replace existing abiotic energy sources with firewood forest should be popularized. This is an urgent task to protect the eco-environment of Tibet today.

关键词： energy sources eco-environment degradation rural Tibet

Oxygen Ion Implantation Enhanced Silicon-Vacancy Photoluminescence and n-Type Conductivity of Ultrananocrystalline Diamond Films

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Chinese Physics Letters 2013年第8期30卷 194-197页

作者： hu Xiao-jun LI Nian College of Chemical Engineering and Materials Science Zhejiang University of TechnologyHangzhou 310014

We report the enhanced silicon-vacancy(Si-V)photoluminescence(PL)intensity and n-type conductivity of ultrananocrystalline diamond(UNCD)films by oxygen ion(O+)*** O+dose increasing from 1014 to 1015 cm^(-2),the PL intensity and n-type conductivity significantly increase by 6 and 45 times,respectively,after 1000℃ *** secondary ion mass spectroscopy mapping measurements show that the content of oxygen is larger in the zone,which has larger content of silicon,indicating that oxygen tends to adhere to *** is suggested that oxygen related Si-V defects are formed,which will enhance the PL intensity and n-type conductivity of UNCD films.

关键词： Diamond Oxygen conductivity

Fast 3D EM scattering and radiation solvers based on MLFMA

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Journal of Systems Engineering and Electronics 2008年第2期19卷 252-258页

作者： hu jun Nie Zaiping Lei Lin hu Jie Gong Xiaodong Zhao huapeng Coll. of Electronic Engineering Univ. of Electronic Science and Technology of China Chengdu 610054 P. R. China

As the fastest integral equation solver to date, the multilevel fast multipole algorithm （MLFMA） has been applied successfully to solve electromagnetic scattering and radiation from 3D electrically large objects. But for very large-scale problems, the storage and CPU time required in MLFMA are still expensive. Fast 3D electromagnetic scattering and radiation solvers are introduced based on MLFMA. A brief review of MLFMA is first given. Then, four fast methods including higher-order MLFMA （HO-MLFMA）, fast far field approximation combined with adaptive ray propagation MLFMA （FAFFA-ARP-MLFMA）, local MLFMA and parallel MLFMA are introduced. Some typical numerical results demonstrate the efficiency of these fast methods.

关键词： scattering and radiation multilevel fast multipole algorithm higher order far field approximation,ray propagation local interaction parallel.

Fast computation of scattering from 3D complex structures by MLFMA

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Journal of Systems Engineering and Electronics 2008年第5期19卷 872-877页

作者： hu jun Nie Zaiping Que Xiaofeng Meng Min Coll. of Electronic Engineering Univ. of Electronic Science and Technology of China Chengdu 610054 P. R. China

This paper introduces the research work on the extension of multilevel fast multipole algorithm （MLFMA） to 3D complex structures including coating object, thin dielectric sheet, composite dielectric and conductor, cavity. The impedance boundary condition is used for scattering from the object coated by thin lossy material. Instead of volume integral equation, surface integral equation is applied in case of thin dielectric sheet through resistive sheet boundary condition. To realize the fast computation of scattering from composite homogeneous dielectric and conductor, the surface integral equation based on equivalence principle is used. Compared with the traditional volume integral equation, the surface integral equation reduces greatly the number of unknowns. To computc conducting cavity with electrically large aperture, an electric field integral equation is applied. Some numerical results are given to demonstrate the validity and accuracy of the present methods.

关键词： impedance boundary condition equivalence theory surface integral equation dielectric cavity.

Kinetic study on the reaction between CO_2-CO and wustite using the isotope exchange method

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International Journal of Minerals,Metallurgy and Materials 2013年第2期20卷 125-130页

作者： Teng Zhang Xiao-jun hu Kuo-Chih Chou State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

To investigate the reaction between CO2-CO and wustite using the isotope exchange method at 1073, 1173, 1273, and 1373 K, the experiment apparatus was designed to simulate the fluidized bed. The chemical rate constant was estimated by considering the effect of gas phase mass transfer on the reaction. It is found that the chemical rate constant is inversely decreased with the increase in the ratio of CO2/CO by volume. The activation energy of reaction is in a linear relationship with the ratio of COs/CO by volume, and the average activation energy is 155.37 kJ/mol.

关键词： kinetics isotope exchange rate constants wustite activation energy

Gas emission source term estimation with 1-step nonlinear partial swarm optimization-Tikhonov regularization hybrid method

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Chinese Journal of Chemical Engineering 2018年第2期26卷 356-363页

作者： Denglong Ma Wei Tan Zaoxiao Zhang jun hu School of Food Equipment Engineering and Science Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University School of Chemical Engineering and Technology Xi'an Jiaotong University School of Chemical Engineering Northwest University

Source term identification is very important for the contaminant gas emission event. Thus, it is necessary to study the source parameter estimation method with high computation efficiency, high estimation accuracy and reasonable confidence interval. Tikhonov regularization method is a potential good tool to identify the source parameters. However, it is invalid for nonlinear inverse problem like gas emission process. 2-step nonlinear and linear PSO （partial swarm optimization）-Tikhonov regularization method proposed previously have estimated the emission source parameters successfully. But there are still some problems in computation efficiency and confidence interval. Hence, a new 1-step nonlinear method combined Tikhonov regularizafion and PSO algorithm with nonlinear forward dispersion model was proposed. First, the method was tested with simulation and experiment cases. The test results showed that 1-step nonlinear hybrid method is able to estimate multiple source parameters with reasonable confidence interval. Then, the estimation performances of different methods were compared with different cases. The estimation values with 1-step nonlinear method were close to that with 2-step nonlinear and linear PSO-Tikhonov regularization method, 1-step nonlinear method even performs better than other two methods in some cases, especially for source strength and downwind distance estimation. Compared with 2-step nonlinear method, 1-step method has higher computation efficiency. On the other hand, the confidence intervals with the method proposed in this paper seem more reasonable than that with other two methods. Finally, single PSO algorithm was compared with 1-step nonlinear PSO-Tikhonov hybrid regularization method. The results showed that the skill scores of 1-step nonlinear hybrid method to estimate source parameters were close to that of single PSO method and even better in some cases. One more important property of 1-step nonlinear PSO-Tikhonov regularization metho

关键词： Parameter estimation Parameter regularization method Source identification Inverse problem

A Perspective on the Dynamics Properties in Polymer Nanocomposites

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Chinese Journal of Polymer Science 2023年第9期41卷 1355-1360,I0005页

作者： Xu-Ze Zhang Zhong-Yuan Lu hu-jun Qian State Key Laboratory of Supramolecular Structure and Materials Institute of Theoretical ChemistryCollege of ChemistryJilin UniversityChangchun130021China

Polymer nanocomposites(PNCs)usually have superior properties than pristine *** the dynamics properties in PNC system is crucial to reveal the mechanism of property change unpon the addition of nanoparticles(NPs),and therefore for a better design of the material *** this short perspective,we summarize recent advances mainly from theoretical and simulation studies of dynamics properties in polymer nanocomposite *** is the"vehicle model"which reveals that diffusion dynamics of sticky NP is coupled to surrounding chain ***,recent simulations demonstrate that such coupling also exists in all-polymer nanocomposite wich is composed of linear polymer chains and single-chain nanoparticles(SCNPs).These SCNPs have almost the same chemical composition as the matrix ***,it is assumed that such all-polymer nanocomposite can act as a model system where there are no enthalpic interactions between NPs and polymer *** the above dynamic coupling was found in the above two different systems containing inorganic NPs or relatively small organic SCNPs,it was found that the length scale of such dynamic coupling(the thickness of the matrix/NP interface)is comparable to the NP size,which is surprisingly consistent in the above two different *** addition,a chain-length dependence of the NP influence on the chain dynamics reported from a recent joint simulaiton and experimental study of all-polymer nanocomposite system,and a theoretical model developed for such phenomena are also *** the end,we give an outlook of this field,especially for possible chainlength dependence of complex dynamics in sticky-NP systems.

关键词： Polymer nanocomposite Dynamics properties Interfacial interaction

Dynamic Event-triggered State Estimation for Nonlinear Coupled Output Complex Networks Subject to Innovation Constraints

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IEEE/CAA Journal of Automatica Sinica 2022年第5期9卷 941-944页

作者： jun hu Chaoqing Jia hui Yu Hongjian Liu Department of Applied Mathematics Harbin University of Science and TechnologyHarbin 150080 School of Automation Harbin University of Science and TechnologyHarbin 150080China Department of Applied Mathematics Harbin University of Science and TechnologyHarbin 150080China School of Mathematics and Physics Anhui Polytechnic UniversityWuhu 241000China

Dear editor,This letter investigates the recursive state estimation(RSE)problem for a class of coupled output complex networks via the dynamic event-triggered communication mechanism(DETCM)and innovation constraints(ICs).Firstly,a DETCM is employed to regulate the transmission ***,in order to improve the reliability of network communication,a saturation function is introduced to constrain the measurement outliers.A new RSE method is provided such that,for all output coupling,DETCM and ICs,an upper bound of state estimation error covariance(SEEC)is presented in a recursive form,whose trace can be minimized via parameterizing the state estimator gain matrix(SEGM).Moreover,the theoretical analysis is given to guarantee that the error dynamic is uniformly ***,a simulation example is illustrated to show the effectiveness of the proposed RSE method.

关键词： method estimation recursive