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Trace Class Toeplitz Operators with Unbounded Symbols on Weighted Bergman Spaces

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Acta Mathematica Sinica,English Series 2010年第8期26卷 1567-1574页

作者： Sui HUANG guang fu CAO Departement of Mathematics Guangzhou University Guangzhou 510006 P. R. China

In this note we construct a function φ in L2（Bn,dμ） which is unbounded on any neighborhood of each boundary point of Bn such that Tφ is a trace class operator on weighted Bergman space Lα2（Bn,dμ） for several ... 详细信息

关键词： Toeplitz operator unbounded function compact operator

The Role of BMOA in the Boundedness of Weighted Composition Operators on the Unit Ball

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Acta Mathematica Sinica,English Series 2014年第2期30卷 323-330页

作者： Chao ZHANG guang fu CAO College of Mathematics and Information Sciences Guangzhou University

We study the weighted composition operators Wh,on Hardy space H2（B） whenever h ∈ BMOA（resp.h ∈ VMOA）.Analogous results are given for Hp（B） spaces and the scale of weighted Bergman *** the latter case,BMOA is... 详细信息

关键词： Weighted composition operator boundedness compactness BMOA VMOA

A Low-Profile Cylindrical Dielectric Resonator Antenna with Bandwidth-Enhancement Under Triple-Mode Resonance

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Journal of Communications and Information Networks 2020年第4期5卷 447-456页

作者： Sen Gao Nengwu Liu guang fu 不详 State Key Laboratory of Millimeter Waves Nanjing 210096China

A low-profile cylindrical dielectric resonator antenna(CDRA)with enhanced impedance bandwidth is proposed via sharing a single triple-mode dielectric ***,the resonant frequencies of TM01d and TM02d modes of a conventional CDRA are maintained far away from each other under central probe ***,a circular disk with an annular ring is loaded around the conventional CDRA,aiming to excite an additional mode between these dual *** electric fields demon-strate that the previous TM_(02δ) mode is transformed into the TM03d mode for the modified CDRA,and an additional TM_(02δ) mode is successfully excited between the TM_(01δ) and TM_(03δ) *** a result,the resonant frequencies of these three radiative modes are reallocated in proximity to each other,thus achieving the desired bandwidth *** addition,considering the small input impedance of the CDRA,a microstrip feeding line is introduced underneath the central probe for good impedance *** these arrangements,the resultant antenna can generate an extended bandwidth under simultaneous radiation of TM_(01δ),TM_(02δ),and TM_(03δ) ***,the proposed CDRA is designed,fabricated,and measured to validate the predicted *** simulated and measured results show that the impedance bandwidth(|S11|<-10 dB of the antenna is dramatically extended from 8%to about 62%(2.835.36 GHz),while keeping a stable conical radiation *** particular,a low profile property of about 0.15 free space wavelength is achieved as well.

关键词： dielectric resonator antenna triple-mode resonance wide impedance bandwidth low profile

Toeplitz Operators with BMO Symbols of Several Complex Variables

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Acta Mathematica Sinica,English Series 2012年第3期28卷 599-608页

作者： Zhong Hua HE guang fu CAO School of Mathematics and Information Sciences Guangzhou University

In this note we prove that the boundedness and compactness of the Toeplitz operator on the Bergman space L2a （Bn） for several complex variables with a BMO1 symbol is completely determined by the boundary behavior of... 详细信息

关键词： Toeplitz operator Bergman space Berezin transform

Wandering Subspaces and Quasi-wandering Subspaces in the Hardy-Sobolev Spaces

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Acta Mathematica Sinica,English Series 2017年第12期33卷 1684-1692页

作者： Jie Sheng XIAO guang fu CAO Nanhu College Jiaxing University Department of Mathematics South China Apicultural University

In this paper, we prove that for -1/2≤β≤0, suppose M is an invariant subspaces of the Hardy Sobolev spaces Hβ^2（D） for Tz^β, then M zM is a generating wandering subspace of M, that is, M = [M zM]Tz^β. Moreover, any non-trivial invariant subspace M of Hβ^2（D） is also generated by the quasi-wandering subspace PMTz^βM^⊥, that is, M = [PMTz^βM^⊥]Tz^β.

关键词： Hardy-Sobolev space invariant subspace wandering subspace quasi-wandering sub- space Beurling type theorem

Operators on Differential Form Spaces for Riemann Surfaces

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Acta Mathematica Sinica,English Series 2007年第5期23卷 925-934页

作者： guang fu CAO Xiao Feng WANG Department of Mathematics Guangzhou University Guangzhou 510405 P. R. China

In the present paper, a problem of Ioana Mihaila is negatively answered on the invertibility of composition operators on Riemann surfaces, and it is proved that the composition operator Cp is Predholm if and only if it is invertible if and only if p is invertible for some special cases. In addition, the Toeplitz operators on ∧1 2, a（M） for Riemann surface M are defined and some properties of these operators are discussed.

关键词： Riemann surface Composition operator Toeplitz operator

Electromigration in eutectic SnAg solder reaction couples with various ambient temperatures and current densities

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 685-690页

作者： guang-chen Xu fu Guo Wan-rong Zhu College of Materials Science and Engineering Beijing University of Technology Beijing 100124 China

The electromigration behavior of eutectic SnAg solder reaction couples was studied at various temperature （25 and 120℃ when the current density was held constant at 104 A/cm^2 or 5×10^3 A/cm^2. Under the current density of 104 A/cm^2, scallop type Cu6Sn5 spalls and migrates towards the direction of electron flow at room ambient temperature （25℃）, but transforms to layer type Cu3Sn and leaves Kirkendall voids in it at high ambient temperature （120℃）. Under the current density of 5×10^3 A/cm^2 plus room ambient temperature, no obvious directional migration of metal atoms/ions is found. Instead, the thermal stress induced by mismatch of dissimilar materials causes the formation of superficial valley at both interfaces. However, when the ambient temperature increases to 120℃, the mobility of metal atoms/ions is enhanced, and then the grains rotate due to the anisotropic property of β-Sn.

关键词： electromigration eutectic solder Joule heating intermetallic compound

Wideband Circularly Polarized Sequentially Rotated Microstrip Antenna Array with Sequential-Phase Feeding Network

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Journal of Communications and Information Networks 2020年第3期5卷 350-357页

作者： Meijiao Sun Nengwu Liu Lei Zhu guang fu National Key Laboratory of Antennas and Microwave Technology Xidian UniversityXi’an 710071China Department of Electrical and Computer Engineering Faculty of Science and TechnologyUniversity of MacaoMacao 999078China State Key Laboratory of Millimeter Waves Nanjing 210096China

A wideband 2×2 sequential-phase fed circularly polarized(CP)microstrip antenna array(MAA)with sequentially rotated elements is ***,the antenna element loaded with shorting pins is studied as compared to the traditional ***,a feeding network is designed to be connected together in a sequential rotation manner,resulting in forming a four-port network to allow symmetrical positioning of CP microstrip patch *** that,straight strips are added to the feeding network in order to increase the distance and reduce coupling between array *** also play a role in improving the impedance matching of the ***,the proposed antenna array is designed and *** results are presented that its impedance bandwidth is about 36.3%at 24.1~34.8 GHz for|S_(11)|<10 dB and axial-ratio(AR)bandwidth is about 20.4%at 24.2~29.7 GHz for AR<3 ***,a peak gain of 11.1 dBic is simulated over the operating frequency range,which is significantly improved compared to the classic and existing works.

关键词： microstrip antenna array sequential-phase feeding network straight strips shorting pins

Weighted Composition Operators between Bergman Spaces with Exponential Weights

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Acta Mathematica Sinica,English Series 2022年第12期38卷 2231-2252页

作者： guang fu CAO Li HE Yi Yuan ZHANG School of Mathematics and Information Science Guangzhou UniversityGuangzhou 510006P.R.China

In this paper,we study some properties of weighted composition operators on a class of weighted Bergman spaces Ap with O 详细信息

In this paper,we study some properties of weighted composition operators on a class of weighted Bergman spaces Ap with Ofunction and the generalized Berezin transform with 0

关键词： Weighted composition operator boundedness compactness Schatten class Bergman spaces

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