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基于自适应射线群的图像边缘检测算法 被引量:3
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作者 张国英 毛辉 +2 位作者 徐宁 杨晨 牟春洁 《计算机工程》 CAS CSCD 北大核心 2011年第4期232-234,共3页
对于存在大量噪声、目标边界模糊且粘连的浮选泡沫类图像,分水岭及阈值法难以准确分割。为此,提出自适应射线群算法检测泡沫边缘,仅访问图像一次,即实现种子区域的提取。去噪后,从种子区域的几何中心位置对称发射出多条射线,根据射线的... 对于存在大量噪声、目标边界模糊且粘连的浮选泡沫类图像,分水岭及阈值法难以准确分割。为此,提出自适应射线群算法检测泡沫边缘,仅访问图像一次,即实现种子区域的提取。去噪后,从种子区域的几何中心位置对称发射出多条射线,根据射线的灰度分布曲线自适应提取泡沫的边缘,并修正边缘。实验结果表明该算法可解决分水岭算法的过分割及不准确分割等问题。 展开更多
关键词 射线群 边缘修正 种子区域 去噪
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Alliance-Authentication Protocol in Clouds Computing Environment 被引量:7
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作者 Zhang Qikun Li Yuanzhang +1 位作者 Song Danjie Tan Yuan 《China Communications》 SCIE CSCD 2012年第7期42-54,共13页
Security has been regarded as one of the hardest problems in the development of cloud computing. This paper proposes an AllianceAuthentication protocol among Hybrid Clouds that include multiple private clouds and/or p... Security has been regarded as one of the hardest problems in the development of cloud computing. This paper proposes an AllianceAuthentication protocol among Hybrid Clouds that include multiple private clouds and/or public clouds. Mu tual authentication protocol among entities in the IntraCloud and InterCloud is proposed. Blind signature and bilinear mapping of automorphism groups are adopted to achieve the InterCloud Alli anceAuthentication, which overcome the complexi ty of certificate transmission and the problem of communication bottlenecks that happen in tradi tional certificatebased scheme. Blind key, instead of private key, is adopted for register, which avoids 展开更多
关键词 Alliance-Authentication direct product DECOMPOSITION bilinear mapping cloud computing
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Impact of apodisation functions on group delay and reflectivity ripple of chirped fiber Bragg gratings
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作者 WANG Lin YAN Feng-ping LI Yi-fan GONG Tao-rong JIAN Shui-sheng 《Optoelectronics Letters》 EI 2006年第6期430-432,共3页
Apodisation technology is introduced to optimize fiber Bragg grating based on the analysis of reflectivity spectrum and group delay response of fiber Bragg gratings. The characteristics of Hamming, Gauss and super-Gau... Apodisation technology is introduced to optimize fiber Bragg grating based on the analysis of reflectivity spectrum and group delay response of fiber Bragg gratings. The characteristics of Hamming, Gauss and super-Gauss functions are discussed and the optimization effects of the three apodisation functions on ripple smoothness of reflectivity spectrum,group delay and linear degree are compared respectively. As a result,the optimization effects of Hamming function is better than other two functions. When the bandwidth is less than ldB,Super-Gauss function is the best choice and proper parameters (G and m) of super-Gauss function can be selected expediently for wider bandwidth and better ripple smoothness of reflectivitv soectrum. 展开更多
关键词 光纤BRAGG光栅 反射光谱 延迟 线性度
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Influence of Hyperon-Hyperon Interaction on Properties of Hadronic Star
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作者 米爱军 尤伟 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第1期133-137,共5页
The influences of hyperon-hyperon interaction on the overall properties of hadronic star are investigated in the framework of relativistic mean field (RMF) theory. For certain hyperon coupling, the weaker hyperon-hy... The influences of hyperon-hyperon interaction on the overall properties of hadronic star are investigated in the framework of relativistic mean field (RMF) theory. For certain hyperon coupling, the weaker hyperon-hyperon interaction can lead to the heavier hadronic star, which accords with the observation of heavy neutron star in X-ray binaries. We find that the threshold densities of the hyperons with larger masses are brought to a lower values with the increase of the hyperon-hyperon interaction. The possibility of the existence of hyperon star is checked with the consideration of hyperon-hyperon interaction. 展开更多
关键词 hyperon interaction relativistic mean field theory hadronic star
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Ermakov System and Plane Curve Motions in Affine Geometries
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作者 QUChang-Zheng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第2期201-204,共4页
It is shown that the Pinney equation, Ermakov systems, and their higher-order generalizations describeself-similar solutions of plane curve motions in centro-affine and affine geometries.
关键词 Pinney equation Ermakov system motion of plane curve affine geometry symmetry group
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Hyperbolic Mapping Classes and Their Lifts on the Bers Fiber Space 被引量:2
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作者 Chaohui ZHANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2007年第1期55-66,共12页
Let S be a Riemann surface with genus p and n punctures. Assume that 3p- 3 + n 〉 0 and n 〉 1. Let a be a puncture of S and let S = S∪{α}. Then all mapping classes in the mapping class group Mods that fixes the pu... Let S be a Riemann surface with genus p and n punctures. Assume that 3p- 3 + n 〉 0 and n 〉 1. Let a be a puncture of S and let S = S∪{α}. Then all mapping classes in the mapping class group Mods that fixes the puncture a can be projected to mapping classes of Mod$ under the forgetful map. In this paper the author studies the mapping classes in Mods that can be projected to a given hyperbolic mapping class in Mode. 展开更多
关键词 Riemann surfaces Absolutely extremal Teichmüller mapping Mapping classes Teichmiiller spaces Bers fiber spaces
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AUTOMRPPHISM GROUP OF LIE ALGEBRA C(t)d/dt
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作者 DU HONG(Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy ofSciences, Beijing 100080, China) 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2003年第2期209-212,共4页
The Lie algebra of derivations of rational function field C(t) is C(t) dt/d.The automorphism group of C(t) is well known as to be isomorphic to the projective linear groupPGL(2, C). In this short note we prove that ev... The Lie algebra of derivations of rational function field C(t) is C(t) dt/d.The automorphism group of C(t) is well known as to be isomorphic to the projective linear groupPGL(2, C). In this short note we prove that every automorphism of C(t) dt/d can be induced in anatural way from an automorphism of C(t). 展开更多
关键词 lie algebra AUTOMORPHISM
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Rationality of quotients by linear actions of affine groups
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作者 BOGOMOLOV Fedor BHNING Christian GRAF VON BOTHMER Hans-Christian 《Science China Mathematics》 SCIE 2011年第8期1521-1532,共12页
LetG = SLn(C)Cn be the (special) affine group. In this paper we study the representation theory of G and in particular the question of rationality for V/G, where V is a generically free G-representation. We show that ... LetG = SLn(C)Cn be the (special) affine group. In this paper we study the representation theory of G and in particular the question of rationality for V/G, where V is a generically free G-representation. We show that the answer to this question is positive (Theorem 6.1) if the dimension of V is sufficiently large and V is indecomposable. We explicitly characterize two-step extensions 0 → S → V → Q → 0, with completely reducible S and Q, whose rationality cannot be obtained by the methods presented here (Theorem 5.3). 展开更多
关键词 RATIONALITY linear group quotients affine groups
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HARMONIC MAPS AND FUNDAMENTAL GROUPS OF NONPOSITIVELY CURVEDRIEMANNIAN MANIFOLDS
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作者 沈纯理 周青 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 1996年第4期491-496,共6页
Using the theory of harmonic maps the authors discuss theproperties of the fundamental group of a complete nonpositivelycurved Riemannian manifold, and prove that the finitely generatedvirtual solvable subgroup of fun... Using the theory of harmonic maps the authors discuss theproperties of the fundamental group of a complete nonpositivelycurved Riemannian manifold, and prove that the finitely generatedvirtual solvable subgroup of fundamental group of a completenonpositively curved Riemannian manifold either is a peripheralsubgroup of fundamental group or can be realized by animmersed totall geodesic closed flat manifold. It generalizessome results of Gromoll-Wolf, Lawson-Yan and Schoen-Yau. 展开更多
关键词 Harmonic map Riemannian manifold Fundamental group
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