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基于投影的二阶段空间圆线拟合算法 被引量:20
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作者 杨伟 陈家新 李济顺 《工程设计学报》 CSCD 北大核心 2009年第2期117-121,共5页
对空间圆线精确拟合算法进行研究.线性和非线性最小二乘法是拟合规则曲线和曲面方程的常见方法.空间圆线作为规则的二次曲线,由于没有特定的曲线方程无法直接使用线性和非线性最小二乘法来进行求解.由于空间圆线可以被看作平面和球面相... 对空间圆线精确拟合算法进行研究.线性和非线性最小二乘法是拟合规则曲线和曲面方程的常见方法.空间圆线作为规则的二次曲线,由于没有特定的曲线方程无法直接使用线性和非线性最小二乘法来进行求解.由于空间圆线可以被看作平面和球面相交形成,圆线特征值可以通过平面和球面特征值求解.提出了基于投影二阶段拟合算法完成空间圆线拟合的方法.对空间圆线拟合原理进行了介绍,通过数据验证了算法的正确性、可行性和精确程度.使用程序进行了算法实现.与贝塞尔和B样条曲线算法精度进行了比较,表明该算法在精度方面具有优势,可用于逆向工程中提高空间拟合算法的精确度. 展开更多
关键词 空间圆线 最小二乘法 拟合 投影
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Linear Combination of Derivative Weighted Composition Operators
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作者 TONG Cezhong GENG Ligang 《Transactions of Tianjin University》 EI CAS 2012年第1期69-72,共4页
The relation between composition operators on the Dirichlet spaces in the open unit disk and derivative weighted composition operators on the Bergman spaces in the open unit disk is investigated firstly,and for a comb... The relation between composition operators on the Dirichlet spaces in the open unit disk and derivative weighted composition operators on the Bergman spaces in the open unit disk is investigated firstly,and for a combination of several derivative weighted composition operators which acts on classic Bergman space,the lower bound of its essential norm is estimated in terms of the boundary data of the symbols of d-composition operators.Some similar results about composition operators on the Dirichlet space are also presented.A necessary condition is given to determine the compactness of the combination of several derivative weighted composition operators on Bergman spaces. 展开更多
关键词 derivative weighted composition operator Bergman space Dirichlet space essential norm
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Asymptotically or super linear cooperative elliptic systems in the whole space 被引量:1
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作者 CHEN GuanWei MA ShiWang 《Science China Mathematics》 SCIE 2013年第6期1181-1194,共14页
Under the assumption that F is asymptotically or super linear as |U|→∞ with U = (u,v)∈R^2, we obtain the existence of ground state solutions of a class of cooperative elliptic systems in NN by using a variant g... Under the assumption that F is asymptotically or super linear as |U|→∞ with U = (u,v)∈R^2, we obtain the existence of ground state solutions of a class of cooperative elliptic systems in NN by using a variant generalized weak linking theorem for strongly indefinite problem developed by Schechter and Zou. To the best of our knowledge, there is no result published concerning the systems in the whole space N^N. 展开更多
关键词 cooperative elliptic systems asymptotically linear superlinear~ the whole space ground statesolutions
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Wellposedness of some quasi-linear Schrdinger equations
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作者 CHEMIN Jean-Yves SALORT Delphine 《Science China Mathematics》 SCIE CSCD 2015年第5期891-914,共24页
This article is devoted to the study of a quasilinear Schrodinger equation coupled with an elliptic equation on the metric g. We first prove that, in this context, the propagation of regularity holds which ensures loc... This article is devoted to the study of a quasilinear Schrodinger equation coupled with an elliptic equation on the metric g. We first prove that, in this context, the propagation of regularity holds which ensures local wellposedness for initial data small enough in H1/2 and belonging to the Besov space B3/2 2,1. In a second step, we establish Strichartz estimates for time dependent rough metrics to obtain a lower bound of the time existence which only involves the B1+ε 2,∞ norm on the initial data. 展开更多
关键词 quasilinear Schrodinger equation Strichartz estimates paradiffential calculus stationary phase method
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On a Quasilinear Elliptic Equation with Superlinear Nonlinearities 被引量:1
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作者 Gao JIA Lina HUANG Xiaojuan ZHANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2016年第2期309-322,共14页
This work is devoted to studying a quasilinear elliptic boundary value problem with superlinear nonlinearities in a weighted Sobolev space in a domain of R^N. Based on the Galerkin method, Brouwer's theorem and th... This work is devoted to studying a quasilinear elliptic boundary value problem with superlinear nonlinearities in a weighted Sobolev space in a domain of R^N. Based on the Galerkin method, Brouwer's theorem and the weighted compact Sobolev-type embedding theorem, a new result about the existence of solutions is revealed to the problem. 展开更多
关键词 Weighted Sobolev space Superlinear Quasilinear elliptic equation
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