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自反空间的一个等价条件 被引量:1
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作者 应明 《同济大学学报(自然科学版)》 EI CAS CSCD 北大核心 2001年第7期855-856,861,共3页
就巴拿赫空间线性算子核等价类的范数可达性的讨论给出了空间自反的一个等价条件 :X自反 ,当且仅当对任一T∈B(X ;Y) ,X/NT 自反且 [x]∈X/NT,‖ [x]‖在
关键词 自反空间 空间 等模代表元 巴拿赫空间 线性算子核 范数可达性 空间几何理论
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基于螺旋理论的多模式移动3-RSR并联机构奇异性分析 被引量:2
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作者 宛宇 张春燕 +3 位作者 朱锦翊 陈致 蒋新星 平安 《轻工学报》 CAS 2020年第3期88-98,共11页
针对3-RSR并联机构在运动过程中的奇异位形,提出了一种基于螺旋理论、几何代数法和空间线性几何理论的新方法,对3-RSR并联机构的全姿态多运动模式进行奇异性分析.该方法首先运用螺旋理论求出3-RSR并联机构的完整雅克比矩阵,然后通过代... 针对3-RSR并联机构在运动过程中的奇异位形,提出了一种基于螺旋理论、几何代数法和空间线性几何理论的新方法,对3-RSR并联机构的全姿态多运动模式进行奇异性分析.该方法首先运用螺旋理论求出3-RSR并联机构的完整雅克比矩阵,然后通过代数法和几何作图法表示出机构各分支的反螺旋,再结合空间线性几何理论分析反螺旋相关性,得出固定模式下机构的奇异性图解,由此对全姿态多运动模式进行奇异性分析.结果表明,该方法能够更加简洁、直观地表示出3-RSR并联机构在两种运动模式下的奇异位形,且不需要大量计算,也适用于其他多模式移动并联机构的奇异位形求解. 展开更多
关键词 并联机构 多模式移动 螺旋理论 空间线性几何理论 奇异性
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SOLVING THE PROPAGATION OF ELECTROMAGNETIC WAVE IN A SIMPLE TWO-DIMENSIONALINHOMOGENEOUS MEDIUM BASED ON SYMPLECTIC GEOMETRICAL THEORY
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作者 Zhao Jin Wu Xianliang Fu Biao(Dept. of Electric Eng. and Info. Science, Anhui University, Hefei 230039)Li Shixiong(Dept. of Mathematics, Anhui University, Hefei 230039) 《Journal of Electronics(China)》 2002年第3期265-269,共5页
A new symplectic geometrical high-frequency approximation method for solving the propagation of electromagnetic wave in the two-dimensional inhomogeneous medium is used in this paper. The propagating caustic problem o... A new symplectic geometrical high-frequency approximation method for solving the propagation of electromagnetic wave in the two-dimensional inhomogeneous medium is used in this paper. The propagating caustic problem of electromagnetic wave is translated into non-caustic problem by the coordinate transform on the symplectic space. The high-frequency approximation solution that includes the caustic region is obtained with the method combining with the geometrical optics. The drawback that the solution in the caustic region can not be obtained with geometrical optics is overcome by this method. The results coincide well with that of finite element method. 展开更多
关键词 Symplectic geometrical theory High-frequency approximation CAUSTICS Two-dimensional inhomogeneous medium
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Geometry and Hardy spaces on spaces of homogeneous type in the sense of Coifman and Weiss 被引量:2
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作者 HAN YanChang HAN YongSheng LI Ji 《Science China Mathematics》 SCIE CSCD 2017年第11期2199-2218,共20页
It is known that the space of homogeneous type introduced by Coifman and Weiss(1971) provides a very natural setting for establishing a theory of Hardy spaces. This paper concentrates on how the geometrical conditions... It is known that the space of homogeneous type introduced by Coifman and Weiss(1971) provides a very natural setting for establishing a theory of Hardy spaces. This paper concentrates on how the geometrical conditions of the space of homogeneous type play a crucial role in building a theory of Hardy spaces via the Littlewood-Paley functions. 展开更多
关键词 spaces of homogeneous type Hardy space singular integrals Carleson measure space BMO
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On the quasidiagonality of Roe algebras
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作者 WEI ShuYun 《Science China Mathematics》 SCIE 2011年第5期1011-1018,共8页
Let X be a noncompact discrete metric space with bounded geometry. Associated with X are two C*-algebras, the so-called uniform Roe algebra B*(X) and coarse Roe algebra C*(X), which arose from the index theory on nonc... Let X be a noncompact discrete metric space with bounded geometry. Associated with X are two C*-algebras, the so-called uniform Roe algebra B*(X) and coarse Roe algebra C*(X), which arose from the index theory on noncompact complete Riemannian manifolds. In this paper, we describe the quasidiagonality of B*(X) and C*(X) in terms of coarse geometric invariants. Some necessary and suficient conditions are given, which involve the Fredholm index and coarse connectedness of metric spaces. 展开更多
关键词 Roe algebra quasidiagonality coarse geometry
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A Survey on Mixed Spin P-Fields
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作者 Huai-Liang CHANG Jun LI +1 位作者 Wei-Ping LI Chiu-Chu Melissa LIU 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2017年第4期869-882,共14页
The mixed spin P-fields (MSP for short) theory sets up a geometric platform to relate Gromov-Witten invariants of the quintic three-fold and Fan-Jarvis-Ruan-Witten invariants of the quintic polynomial in five variab... The mixed spin P-fields (MSP for short) theory sets up a geometric platform to relate Gromov-Witten invariants of the quintic three-fold and Fan-Jarvis-Ruan-Witten invariants of the quintic polynomial in five variables. It starts with Wittens vision and the P-fields treatment of GW invariants and FJRW invaxiants. Then it briefly discusses the master space technique and its application to the set-up of the MSP moduli. Some key results in MSP theory are explained and some examples are provided. 展开更多
关键词 Mixed Spin P-fields GW invariants FJRW invariants P-fields Cosection localization
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