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Search Results: 1 - 10 of 34401 matches for " Zehua Zhou "
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Weighted Composition Operators between different Bloch-type Spaces in Polydisk
Zehua Zhou
Mathematics , 2005,
Abstract: Let $\phi(z)=(\phi_1(z), ...,\phi_n(z))$ be a holomorphic self-map of $U^n$ and $\psi(z)$ a holomorphic function on $U^n,$ where $U^n$ is the unit polydisk of ${\Bbb C}^n.$ Let $p\geq 0,$ $q\geq 0$, this paper gives some necessary and sufficient conditions for the weighted composition operator $W_{\psi,\phi}$ induced by $\psi$ and $\phi$ to be bounded and compact between $p$-Bloch space ${\cal B}^p(U^n)$ and $q$-Bloch space ${\cal B}^q(U^n).$
The essential norms of composition operators between generalized Bloch spaces in the polydisc and their applications
Zhou Zehua,Liu Yan
Journal of Inequalities and Applications , 2006,
Abstract: Let be the unit polydisc of and a holomorphic self-map of . , and denote the -Bloch space, little -Bloch space, and little star -Bloch space in the unit polydisc , respectively, where . This paper gives the estimates of the essential norms of bounded composition operators induced by between ( or ) and ( or ). As their applications, some necessary and sufficient conditions for the (bounded) composition operators to be compact from ( or ) into ( or ) are obtained.
Composition operators in the Lipschitz Space of the Polydiscs
Zhongshan Fang,Zehua Zhou
Mathematics , 2007,
Abstract: In 1987, Shapiro shew that composition operator induced by symbol $\phi$ is compact on the Lipschltz space if and only if the infinity norm of $\phi$ is less than 1 by a spectral-theoretic argument, where $\phi$ is a holomorphic self-map of the unit disk. In this paper, we shall generalize Shapiro's result to the $n$-dimensional case.
Extended Ces$\acute{a}$RO Operators between Generalized Besov Spaces and Bloch Type Spaces in the Unit Ball
Zehua Zhou,Min Zhu
Mathematics , 2007,
Abstract: Let $g$ be a holomorphic map of $B$, where $B$ is the unit ball of ${C}^n$. Let $0-1$ and $\alpha>0$. This paper gives some necessary and sufficient conditions for the Extended Ces$\acute{a}$ro Operators induced by $g$ to be bounded or compact between generalized Besov space $B(p,q)$ and $\alpha$- Bloch space ${\mathcal B}^\alpha.$
Difference of composition operators in the Polydiscs
Zhongshan Fang,Zehua Zhou
Mathematics , 2007,
Abstract: This paper gives some simple estimates of the essential norm for the difference of composition operators induced by $\phi$ and $\psi$ acting on bounded function space in the unit polydiscs $U^n$, where $\phi(z)$ and $\psi(z)$be holomorphic self-maps of $U^n$. As its applications, a characterization of compact difference is given for composition operators acting on the bounded function spaces.
The Essential Norm of Composition Operator between Generalized Bloch Spaces in Polydiscs and its Applications
Zehua Zhou,Yan Liu
Mathematics , 2005, DOI: 10.1155/JIA/2006/90742
Abstract: Let $U^{n}$ be the unit polydisc of ${\Bbb C}^{n}$ and $\phi=(\phi_1, >..., \phi_n)$ a holomorphic self-map of $U^{n}.$ By ${\cal B}^p(U^{n})$, ${\cal B}^p_{0}(U^{n})$ and ${\cal B}^p_{0*}(U^{n})$ denote the $p$-Bloch space, Little $p$-Bloch space and Little star $p$-Bloch space in the unit polydisc $U^n$ respectively, where $p, q>0$. This paper gives the estimates of the essential norms of bounded composition operators $C_{\phi}$ induced by $\phi$ between ${\cal B}^p(U^n)$ (${\cal B}^p_{0}(U^n)$ or ${\cal B}^p_{0*}(U^n)$) and ${\cal B}^q(U^n)$ (${\cal B}^q_{0}(U^n)$ or ${\cal B}^q_{0*}(U^n)$). As their applications, some necessary and sufficient conditions for the bounded composition operators $C_{\phi}$ to be compact from ${\cal B}^p(U^n)$ $({\cal B}^p_{0}(U^n)$ or ${\cal B}^p_{0*}(U^n))$ into ${\cal B}^q(U^n)$ (${\cal B}^q_{0}(U^n)$ or ${\cal B}^q_{0*}(U^n)$) are obtained.
Weighted Composition Operators from $F(p,q,s)$ to Bloch Type Spaces on the Unit Ball
Zehua Zhou,Renyu Chen
Mathematics , 2005,
Abstract: Let $\phi(z)=(\phi_1(z),...,\phi_n(z))$ be a holomorphic self-map of $B$ and $\psi(z)$ a holomorphic function on $B$, where $B$ is the unit ball of ${\Bbbb C}^n$. Let $0-1$ and $\alpha\geq 0,$ this paper gives some necessary and sufficient conditions for the weighted composition operator $\wco$ induced by $\phi$ and $\psi$ to be bounded and compact between the space $\Fs$ and $\alpha$-{\sl Bloch} space $\beta^\alpha.$
Compact Composition Operators on the Bloch Space in Bounded Symmetric Domains
Zehua Zhou,Yan Liu
Mathematics , 2005,
Abstract: Let $\Omega$ be a bounded symmetric domain except the two exceptional domains of ${\Bbb C}^N$ and $\phi$ a holomorphic self-map of $\Omega.$ This paper gives a sufficient and necessary condition for the composition operator $C_{\phi}$ induced by $\phi$ to be compact on the Bloch space $\beta(\Omega)$.
PREPARATION AND MICROWAVE ATTENUATION PROPERTY IN THE X BAND OF SiC–C COMPOSITES
ZEHUA ZHOU,ZEHUA WANG,YU YI,SHAOQUN JIANG
Ceramics-Silikáty , 2011,
Abstract: For developing an effective, low-cost method on preparation of microwave attenuation material, SiC–C composites with different additions of graphite grain were fabricated with solid phase sintering and liquid phase sintering, respectively. The microwave attenuation and the relative electrical properties of composites in the X band were measured. The results show that both methods are cost-effective and easily controllable processes and Solid phase sintering was more suitable to obtain SiC-C attenuation composites than the liquid phase sintering. The composite with 3 wt.% C prepared by solid phase sintering exhibited the best microwave attenuation, the biggest attenuation was -40.5 dB and most attenuations were above -30 dB in the whole X band. Furthermore, the microwave attenuation of composites depended strongly on the C additions; Match of interface of wave impedance and high wave consumption are both necessary for microwave attenuation materials.
Composition operators on generalized Bloch spaces of the polydisk
Dana D. Clahane,Stevo Stevic,Zehua Zhou
Mathematics , 2005,
Abstract: Let p,q>0. We extend to the n-polydisk previous one-variable characterization results of K. Madigan on the $p$-Lipschitz space and K. Madigan/A. Matheson on the Bloch space by obtaining function-theoretic conditions on a holomorphic self-map of the polydisk such that the induced composition operator is bounded or compact between p- and q-Bloch spaces of the polydisk. These conditions turn out to be different in the cases when p is in (0,1) and when p is at least 1. We also obtain corresponding characterization results for composition operators between generalized little p- and q-Bloch spaces of the polydisk.
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