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The closures of (U+K)-orbits of essentially normal triangular operator models

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Science China Mathematics 2010年第11期53卷 1045-1066页

作者： ZHAI FaHui 1,& GUO XianZhou 2.1 Department of Mathematics,Qingdao university of Science and technology,Qingdao 2.6061,China 2.School of Sciences,Hebei university of technology,tianjin 300401,China 1. Department of Mathematics Qingdao University of Science and Technology Qingdao 266061 China2. School of Sciences Hebei University of Technology Tianjin 300401 China

The (U + K)-orbit of a bounded linear operator T acting on a Hilbert space H is defined as (U + K)(T)={R-1 T R:R is invertible of the form unitary plus compact on H}.In this paper,we first characterize the closure of the (U + K)-orbit of an essentially normal triangular operator T satisfying H={ker(T-λI):λ∈ρ F (T)} and σ p (T*)=ф.After that,we establish certain essentially normal triangular operator models with the form of the direct sums of triangular operators,adjoint of triangular operators and normal operators,show that such operator models generate the same closed (U + K)-orbit if they have the same spectral picture,and describe the closures of the (U + K)-orbits of these operator *** generalize some known results on the closures of (U + K)-orbits of essentially normal operators,and provide more positive cases to an open conjecture raised by Marcoux as Question 2.in his article "A survey of (U + K)-orbits".

关键词： (U+K)-orbit essentially normal operator triangular operator

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Synthesis of nanostructural ZnO using hydrothermal method for dye-sensitized solar cells

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Science China(Technological Sciences) 2010年第4期53卷 1146-1149页

作者： WANG ChunXiao1,2.ZHANG XiaoDan1,WANG DongFeng1,YANG ZhenHua1,2.JI WeiWei1,ZHANG CunShan2.& ZHAO Ying1 1 Institute of Photo-electronic Thin Film Devices and technology of Nankai university,Key Laboratory of Photo-electronic Information Science and technology(Nankai university),Ministry of Education,tianjin 300071,China 2.College of Information Engineering,Hebei university of technology,tianjin 300130,China 1. Key Laboratory of Photo-electronic Information Science and technology (Nankai university) Ministry of Education Institute of Photo-electronic Thin Film Devices and Technology of Nankai University Tianjin 300071 China2. College of Information Engineering Hebei University of Technology Tianjin 300130 China

ZnO nanocrystals with different morphologies were successful synthesized by a simple hydrothermal method combined with and without hexadecyl trimethyl ammonium bromide(CTAB).The phases and morphologies of the products were measured using X-ray diffraction(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM),*** results indicated that the ZnO nanocrystals with different morphologies were of hexagonal wurtzite *** nanorods were obtained without using CTAB,and then the morphology of ZnO changed to ZnO nanoflower and the density of nanoflower became denser with the increase of CTAB *** nanoflower and ZnO nanorod as photoanode were applied to dye-sensitized solar cells(DSSC),*** nanoflower shows a higher dye loading,so DSSC with the use of the ZnO nanoflower possesses a higher conversion efficiency than ZnO nanorod.

关键词： DSSC ZnO

Universal approximation of polygonal fuzzy neural networks in sense of K-integral norms

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Science China(Information Sciences) 2011年第11期54卷 2307-2323页

作者： WANG GuiJun 1 & LI XiaoPing 2.1 School of Mathematics Science,tianjin Normal university,tianjin 300387,China 2.School of Management,tianjin Normal university,tianjin 300387,China 1. School of Mathematics Science Tianjin Normal University Tianjin 300387 China2. School of Management Tianjin Normal University Tianjin 300387 China

In this paper,we introduce polygonal fuzzy numbers to overcome the operational complexity of ordinary fuzzy numbers,and obtain two important inequalities by taking advantage of their fine *** presenting an actual example,we demonstrate that the approximation capability of polygonal fuzzy numbers is ***,the concepts of K-quasi-additive integrals and K-integral norms are *** the polygonal fuzzy numbers space satisfies separability,the density problems for several functions spaces can be studied,by means of fuzzy-valued simple functions and fuzzy-valued Bernstein *** establish that the class of the integrally-bounded fuzzy-valued functions spans a complete and separable metric space in the K-integral ***,in the sense of K-integral norms,the universal approximation of fourlayer regular polygonal fuzzy neural networks for fuzzy-valued simple functions is ***,we show that this type of networks also possesses universal approximation for the class of integrally-bounded fuzzyvalued *** result indicates that the approximation capability which regular polygonal fuzzy neural networks for continuous fuzzy systems can be extended as for general integrable systems.

关键词： polygonal fuzzy numbers K-quasi-additive integrals K-integral norms polygonal fuzzy neural networks universal approximations

THz source based on optical Cherenkov radiation

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Science China(Information Sciences) 2012年第1期55卷 27-34页

作者： YAO JianQuan1,2.LIU PengXiang1,2.XU DeGang1,2.LV YingJin1,2.LV Da1,2.1Institute of Laser&Optoelectronics,College of Precision Instruments and Opto-Electronic Engineering,tianjin university,tianjin 300072.China 2.ey Laboratory of Opto-electronics Information technology(tianjin university),Ministry of Education,tianjin 300072.China 1. Institute of Laser & Optoelectronics College of Precision Instruments and Opto-Electronic Engineering Tianjin University Tianjin 300072 China2. Ministry of Education Key Laboratory of Opto-electronics Information Technology (Tianjin University) Tianjin 300072 China

Terahertz(THz)technique has attracted considerable interest due to its broad application *** source is a crucial part of THz science and *** Cherenkov radiation in electro-optic crystals is a promising method of THz generation,because phase-matching is automatically *** this paper,we introduced two types of THz source based on optical Cherenkov radiation:both broadband and tunable *** mechanism of radiation was analyzed and recent development was reviewed in *** future of THz source based on optical Cherenkov radiation was also forecasted.

关键词： Terahertz source optical rectification dierence frequency generation Cherenkov radiation

Guidance of an Ecological Economy,Accelerate the Sustainable Development of Agricultural Economy

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Guidance of an Ecological Economy,Accelerate the Sustainable...

Preliminary Discussion on the Enhancement of the Soft Power of Lang Fang City

Integrative Research of the Beijing-tianjin-Langfang Based on Regional Economic Development--International Conference of Lang Fang Economy and Industrial Clusters

作者： Zou Na~1 Liu Hongchun~2.1 Wuhan university Of technology Wuhan Hubei 430070 China {2. beichen tianjin 300401 China

＜正＞With ecological and economic guidance of agriculture,agricultural economy to accelerate the development of Lang fang,enhances the economic,social and ecological benefits of far-reaching historical significance and practical significance. First,with the guidance of ecological agriculture and economic thought,is to reflect on four years of the history of agricultural production outlined in the Code of experience in a *** is a long history of ancient civilizations,the

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Preliminary Discussion on the Enhancement of the Soft Power ...

Minimal symmetric submanifolds in compact Riemannian symmetric spaces

Integrative Research of the Beijing-tianjin-Langfang Based on Regional Economic Development--International Conference of Lang Fang Economy and Industrial Clusters

作者： Bi Liuhe~1 Zhao Biao~2.1 Wuhan university Of technology Wuhan Hubei 430070 China {2. beichen tianjin 300401 China

＜正＞How a city attracts the external and be cognized by the internal depends on the strength of the city,it also be known as City *** Power is a comprehensive concept that includes both hard power and soft *** so-ca...

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Chinese Science Bulletin 1998年第21期43卷 1786-1789页

作者： LIANG Ke 1 and JIN Quanqin 1,2.1. Department of Mathematics, Nankai university, tianjin 300071, China 2. Department of Mathematics, Hebei university, Baoding 071002. China Department of Mathematics Nankai University Tianjin China Department of Mathematics Hebei University Baoding China

A necessary and sufficient condition for a symmetric submanifold to be minimal in its ambient compact Riemannian symmetric space is given. By this condition a complete classification of non- minimal symmetric submanif... 详细信息

关键词： symmetric space symmetric submanifold mean curvature vector.

Impulsive Homoclinic Chaos in Van der Pol Jerk System

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Transactions of tianjin university 2010年第6期16卷 457-460页

作者：丁玉梅张琪昌 School of Mechanical Engineering Tianjin University School of Sciences Tianjin University of Science and Technology

A 3D continuous autonomous chaotic system is reported, which contains a cubic term and six system parameters. Basic dynamic properties of the new Van der Pol Jerk system are studied by means of theoretical analysis and numerical simulation. Based on the Silnikov theorem, the chaotic characterisitics of the dynamic system are discussed. Using Cardano formula and series solution of differential equation, eigenvalue problem and the existence of homoclinic orbit are studied. Furthermore, a rigorous proof for th...

关键词： chaotic system homoclinic orbit Silnikov theorem

Simulation study of phase retrieval for hard X-ray in-line phase contrast imaging

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Science China(Physics,Mechanics & Astronomy) 2005年第4期48卷 450-458页

作者： YU Bin1,2. PENG Xiang1,2. TIAN Jindong1, NIU Hanben1, DIAO Luhong3 & LI Hua3 1. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, Institute of Optoelec- tronics, Shenzhen university, Shenzhen 518060, China 2. State Key Laboratory of Precision Measuring technology and Instruments, {2. university, {2. 300072.China 3. Key Laboratory of Intelligent Information Processing, Institute of Computing technology, Chinese Academy of Sciences, Beijing 100080,China 1. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education Institute of Optoelectronics Shenzhen University 518060 Shenzhen China 2. State Key Laboratory of Precision Measuring technology and Instruments Tianjin University 300072 Tianjin China 3. Key Laboratory of Intelligent Information Processing Institute of Computing Technology Chinese Academy of Sciences 100080 Beijing China

Two algorithms for the phase retrieval of hard X-ray in-line phase contrast imaging are presented. One is referred to as Iterative Angular Spectrum Algorithm (IASA) and the other is a hybrid algorithm that combines IASA with TIE (transport of intensity equation). The calculations of the algorithms are based on free space propagation of the angular spectrum. The new approaches are demonstrated with numerical simulations. Comparisons with other phase retrieval algorithms are also performed. It is shown that the phase retrieval method combining the IASA and TIE is a promising technique for the application of hard X-ray phase contrast imaging.

关键词： X-ray optics, phase contrast imaging, phase retrieval, angular spectrum, hard X-ray.