• 제목/요약/키워드: JIA

검색결과 1,332건 처리시간 0.022초

ON A CLASS OF COMPLETE NON-COMPACT GRADIENT YAMABE SOLITONS

  • Wu, Jia-Yong
    • 대한수학회보
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    • 제55권3호
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    • pp.851-863
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    • 2018
  • We derive lower bounds of the scalar curvature on complete non-compact gradient Yamabe solitons under some integral curvature conditions. Based on this, we prove that potential functions of Yamabe solitons have at most quadratic growth for distance function. We also obtain a finite topological type property on complete shrinking gradient Yamabe solitons under suitable scalar curvature assumptions.

Face Detection and Extraction Based on Ellipse Clustering Method in YCbCr Space

  • Jia, Shi;Woo, Chong-Ho
    • 한국멀티미디어학회논문지
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    • 제13권6호
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    • pp.833-840
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    • 2010
  • In this paper a method for detecting and extracting the face from the image in YCbCr spaceis proposed. The face region is obtained from the complex original image by using the difference method and the face color information is taken from the reduced face region throughthe Ellipse clustering method. The experimental results showed that the proposed method can efficiently detect and extract the face from the original image under the general light intensity except for low luminance.

COMPOSITION OPERATORS FROM HARDY SPACES INTO α-BLOCH SPACES ON THE POLYDISK

  • SONGXIAO LI
    • 대한수학회논문집
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    • 제20권4호
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    • pp.703-708
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    • 2005
  • Let ${\varphi}(z)\;=\;({\varphi}_1(Z),{\cdots},{\varphi}_n(Z))$ be a holomorphic self­map of $\mathbb{D}^n$, where $\mathbb{D}^n$ is the unit polydisk of $\mathbb{C}^n$. The sufficient and necessary conditions for a composition operator to be bounded and compact from the Hardy space $H^2(\mathbb{D}^n)$ into $\alpha$-Bloch space $\beta^{\alpha}(\mathbb{D}^n)$ on the polydisk are given.

GLOBAL ASYMPTOTIC STABILITY FOR A DIFFUSION LOTKA-VOLTERRA COMPETITION SYSTEM WITH TIME DELAYS

  • Zhang, Jia-Fang;Zhang, Ping-An
    • 대한수학회보
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    • 제49권6호
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    • pp.1255-1262
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    • 2012
  • A type of delayed Lotka-Volterra competition reaction-diffusion system is considered. By constructing a new Lyapunov function, we prove that the unique positive steady-state solution is globally asymptotically stable when interspecies competition is weaker than intraspecies competition. Moreover, we show that the stability property does not depend on the diffusion coefficients and time delays.

STATIONARY PATTERNS FOR A PREDATOR-PREY MODEL WITH HOLLING TYPE III RESPONSE FUNCTION AND CROSS-DIFFUSION

  • Liu, Jia;Lin, Zhigui
    • 대한수학회보
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    • 제47권2호
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    • pp.251-261
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    • 2010
  • This paper deals with a predator-prey model with Holling type III response function and cross-diffusion subject to the homogeneous Neumann boundary condition. We first give a priori estimates (positive upper and lower bounds) of positive steady states. Then the non-existence and existence results of non-constant positive steady states are given as the cross-diffusion coefficient is varied, which means that stationary patterns arise from cross-diffusion.

ADDITIVITY OF LIE MAPS ON OPERATOR ALGEBRAS

  • Qian, Jia;Li, Pengtong
    • 대한수학회보
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    • 제44권2호
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    • pp.271-279
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    • 2007
  • Let A standard operator algebra which does not contain the identity operator, acting on a Hilbert space of dimension greater than one. If ${\Phi}$ is a bijective Lie map from A onto an arbitrary algebra, that is $${\phi}$$(AB-BA)=$${\phi}(A){\phi}(B)-{\phi}(B){\phi}(A)$$ for all A, B${\in}$A, then ${\phi}$ is additive. Also, if A contains the identity operator, then there exists a bijective Lie map of A which is not additive.

A GENERAL RICCI FLOW SYSTEM

  • Wu, Jia-Yong
    • 대한수학회지
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    • 제55권2호
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    • pp.253-292
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    • 2018
  • In this paper, we introduce a general Ricci flow system, which is closely linked with the Ricci flow and the renormalization group flow, etc. We prove the short-time existence, the entropy functionals, the higher derivatives estimates and the compactness theorem for this general Ricci flow system on closed Riemannian manifolds. These basic results are useful tools to understand the singularities of this system.