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弱 Berwald 双挠积 Finsler 度量 被引量:1
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作者 邓香香 何勇 倪琪慧 《理论数学》 2021年第7期1389-1399,共11页
本文主要研究了双挠积 Finsler 度量的平均 Berwald 曲率和迷向平均 Berwald 曲率,给出了双 挠积 Finsler 度量是弱 Berwald 度量的充要条件,证明了在一定条件下具有迷向平均 Berwald 曲率的双挠积 Finsler 度量是弱 Berwald 度量。
关键词 Finsler 度量 挠积 Berwald 度量 迷向平均 Berwald 曲率
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Berwald双挠积Finsler度量 被引量:1
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作者 邓香香 何勇 张娜 《新疆师范大学学报(自然科学版)》 2021年第2期10-16,共7页
设F_(1)和F_(2)是两个Finsler度量,f_(1)和f_(2)是乘积流形M=M_(1)×M_(2)上的非负光滑函数,双挠积Finsler度量是在乘积流形上赋予的Finsler度量F_(2)=f_(2)_(2)F_(1)^(2)+f_(1)^(2)F_(2)^(2).文章首先推导出双挠积Finsler度量的Ber... 设F_(1)和F_(2)是两个Finsler度量,f_(1)和f_(2)是乘积流形M=M_(1)×M_(2)上的非负光滑函数,双挠积Finsler度量是在乘积流形上赋予的Finsler度量F_(2)=f_(2)_(2)F_(1)^(2)+f_(1)^(2)F_(2)^(2).文章首先推导出双挠积Finsler度量的Berwald联络系数,其次给出了双挠积Finsler度量的Berwald曲率系数公式,最后得到双挠积Finsler度量是Berwald度量的充要条件,并证明了具有迷向Berwald曲率的双挠积Finsler度量是Berwald度量。 展开更多
关键词 FINSLER度量 挠积 Berwald度量 Berwald曲率 迷向Berwald曲率
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平衡挠积埃尔米特流形
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作者 李淑雯 卢晓英 +1 位作者 何勇 加依达尔·里扎别克 《理论数学》 2023年第10期2908-2915,共8页
设(M1,g) 和(M2,h) 是两个埃尔米特流形,挠积埃尔米特流形(M1×fM2,G) 是赋予了埃尔米特度量 G = g+f2h 的乘积流形M1×M2,这里f是M1×M2上的光滑函数。本文推导出挠积埃尔米特流形的挠率和挠率(1,0)形式,给出埃尔米特流形(... 设(M1,g) 和(M2,h) 是两个埃尔米特流形,挠积埃尔米特流形(M1×fM2,G) 是赋予了埃尔米特度量 G = g+f2h 的乘积流形M1×M2,这里f是M1×M2上的光滑函数。本文推导出挠积埃尔米特流形的挠率和挠率(1,0)形式,给出埃尔米特流形(M1×fM2,G)平衡的充分必要条件。 展开更多
关键词 埃尔米特流形 挠积 平衡流形
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局部射影平坦双挠积芬斯勒度量
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作者 邓香香 何勇 +1 位作者 张娜 李淑雯 《数学进展》 CSCD 北大核心 2023年第5期939-944,共6页
设F_(1)和F_(2)分别是光滑流形M_(1)和M_(2)上的芬斯勒度量,双挠积芬斯勒度量是在乘积流形M=M_(1)×M_(2)上赋予的芬斯勒度量F^(2)=f^(2)_(2)F^(2)_(1)+f^(2)_(1)F^(2)_(2),其中f_(1)和f_(2)是乘积流形M上的非负光滑函数.本文给出... 设F_(1)和F_(2)分别是光滑流形M_(1)和M_(2)上的芬斯勒度量,双挠积芬斯勒度量是在乘积流形M=M_(1)×M_(2)上赋予的芬斯勒度量F^(2)=f^(2)_(2)F^(2)_(1)+f^(2)_(1)F^(2)_(2),其中f_(1)和f_(2)是乘积流形M上的非负光滑函数.本文给出了局部射影平坦双挠积芬斯勒度量的微分方程刻画,进而证明了局部射影平坦双挠积芬斯勒度量是局部闵可夫斯基度量. 展开更多
关键词 芬斯勒度量 挠积 局部射影平坦 局部闵可夫斯基度量
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双挠积复Finsler流形的局部对偶平坦性
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作者 肖维 何勇 +1 位作者 栗嘉慧 邓香香 《数学进展》 CSCD 北大核心 2023年第2期371-376,共6页
设(M_(1),F_(1))和(M_(2),F_(2))是两个强凸的复Finsler流形,λ_(1)和λ_(2)是乘积流形M=M_(1)×M_(2)上的光滑实值函数,双挠积复Finsler流形(M1×(λ_(1,)λ_(2))M_(2),F)是在乘积流形上赋予了复Finsler度量F^(2)=λ_(1)^(2)F_... 设(M_(1),F_(1))和(M_(2),F_(2))是两个强凸的复Finsler流形,λ_(1)和λ_(2)是乘积流形M=M_(1)×M_(2)上的光滑实值函数,双挠积复Finsler流形(M1×(λ_(1,)λ_(2))M_(2),F)是在乘积流形上赋予了复Finsler度量F^(2)=λ_(1)^(2)F_(1)^(2)+λ_(2)^(2)F_(2)^(2)的复Finsler流形.本文给出了双挠积复Finsler流形是局部对偶平坦流形的充要条件. 展开更多
关键词 挠积 复FINSLER流形 局部对偶平坦
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DIFFERENTIAL QUADRATURE FOR AXISYMMETRIC GEOMETRICALLY NONLINEAR ANALYSIS OF CIRCULAR PLATES
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作者 王鑫伟 周光明 贾德财 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1995年第2期134-142,共9页
New developments have been made on the applications of the differential quadrature(DQ)method to analysis of structural problems recently.The method is used to obtain solutions of large deflections, membrane and bendin... New developments have been made on the applications of the differential quadrature(DQ)method to analysis of structural problems recently.The method is used to obtain solutions of large deflections, membrane and bending stresses of circular plates with movable and immovable edges under uniform pressures or a central point load.The shortcomings existing in the earlier analysis by the DQ method have been overcome by a new approach in applying the boundary conditions. The accuracy and the efficiency of the newly developed method for solving nonlinear problems are demonstrated. 展开更多
关键词 circular plates nonlinear analysis axisymmetric bodies differential quadrature large deflection
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实空间形式到四元欧氏空间的Lagrangian等距浸入(英文)
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作者 徐翔 《复旦学报(自然科学版)》 CAS CSCD 北大核心 2007年第2期175-183,共9页
运用子流形理论从挠积角度研究了从实空间形式到四元欧氏空间的拉格朗日等距浸入,给出了实空间形式Mn(0)的挠积分解与相应的到四元欧氏空间的拉格朗日等距浸入之间的关系,构造了一个非平凡的适应拉格朗日等距浸入的实例.
关键词 拉格朗日等距浸入 挠积 四元欧氏空间
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A sixth-order wavelet integral collocation method for solving nonlinear boundary value problems in three dimensions 被引量:1
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作者 Zhichun Hou Jiong Weng +2 位作者 Xiaojing Liu Youhe Zhou Jizeng Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2022年第2期81-92,I0003,共13页
A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate e... A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate expression of multiple integrals of a continuous function defined in a three-dimensional bounded domain is proposed by combining wavelet expansion and Lagrange boundary extension.Through applying such an integral technique,during the solution of nonlinear partial differential equations,the unknown function and its lower-order partial derivatives can be approximately expressed by its highest-order partial derivative values at nodes.A set of nonlinear algebraic equations with respect to these nodal values of the highest-order partial derivative is obtained using a collocation method.The validation and convergence of the proposed method are examined through several benchmark problems,including the eighth-order two-dimensional and fourth-order three-dimensional boundary value problems and the large deflection bending of von Karman plates.Results demonstrate that the present method has higher accuracy and convergence rate than most existing numerical methods.Most importantly,the convergence rate of the proposed method seems to be independent of the order of the differential equations,because it is always sixth order for second-,fourth-,sixth-,and even eighth-order problems. 展开更多
关键词 Nonlinear boundary value problems Eighth-order derivative Coiflet wavelet Integral collocation method Von Karman plate
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