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用正形数胸高形数和经验回归方程编制人工林立木材积表 被引量:6
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作者 郑小贤 刘东兰 +1 位作者 宋新民 刘玉洪 《林业科技》 北大核心 1996年第5期1-4,共4页
用正形数、胸高形数和经验回归方程3种方法编制的樟子松人工林二元材积表,其精度比较的结果表明,正形数法最优,其次是胸高形数法。直接用经验回归方程编制的一元材积表和利用树高曲线把胸高形数二元材积表导算成一元材积表的精度比... 用正形数、胸高形数和经验回归方程3种方法编制的樟子松人工林二元材积表,其精度比较的结果表明,正形数法最优,其次是胸高形数法。直接用经验回归方程编制的一元材积表和利用树高曲线把胸高形数二元材积表导算成一元材积表的精度比较结果表明,后者优于前者.因此,利用胸高形数是编制材积表的有效方法。 展开更多
关键词 樟子松 人工林 正形数 胸高形数 材积表
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正形数和胸高形数的关系及特性的讨论 被引量:4
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作者 李悦黎 《林业科学》 CAS CSCD 北大核心 1995年第5期467-473,共7页
胸高形数f1.3是一系列正形数fn的一个子集,具有fn的特性。根据数学推导和伐倒木计算;fn的特性与相对高n和形状指数r、f1.3与树高h和r的关系如下:当r固定时,fn随n的增大而增大,f1.3随h的增大而减小;当... 胸高形数f1.3是一系列正形数fn的一个子集,具有fn的特性。根据数学推导和伐倒木计算;fn的特性与相对高n和形状指数r、f1.3与树高h和r的关系如下:当r固定时,fn随n的增大而增大,f1.3随h的增大而减小;当0.03≤n≤0.22时,同一n的fn、当5.87≤h≤43.33m时,同一h的f1.3均可反映体型,它们的值越大则体型越饱满,亦可作为材积换算因子;当0.22<n≤0.37时,同一n的fn、当3.51≤h<5.87m时,同一h的f1.3仅作为材积换算因子比较合适;当0.37<n<1时,同一n的fn、当1.3<h<3.51m时,同一h的f1.3除一小部分(其大小团树种不同而异)可作为材积换算因子外,大部分无论是反映体型还是作为材积换算因子均不理想。 展开更多
关键词 正形数 胸高形数 干形 测树学
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带、去皮正形数系列之间的变化规律及应用 被引量:5
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作者 杜纪山 《浙江林业科技》 北大核心 1990年第2期20-23,35,共5页
用陕西省主要林区收集的油松标准地、标准木分析了带、去皮正形数系列f_(0.nh)(0.n=0.0,0.02,0.04,0.06,0.08,0.1,0.15,0.2,0.25,0.3,0.4,0.5)之间的变化规律n对林分得到:当0.n=0.15时,f_(0.nh)(带皮)≈f_(0.n)(去皮);当0.n<0.15时,f... 用陕西省主要林区收集的油松标准地、标准木分析了带、去皮正形数系列f_(0.nh)(0.n=0.0,0.02,0.04,0.06,0.08,0.1,0.15,0.2,0.25,0.3,0.4,0.5)之间的变化规律n对林分得到:当0.n=0.15时,f_(0.nh)(带皮)≈f_(0.n)(去皮);当0.n<0.15时,f_(0.nh)(带皮)<f_(0.nh)(去皮);当0.15<0.n≤0.5时,f_(0.nh)(带皮)>f_(0.nh)(去皮)。单株木也是如此。应用关系式f_(0.15h)(带皮)≈f_(0.15h)(去皮),可根据0.15h处的带、去皮直径,得到树皮率系数,为准确估计单株木树干树皮率、去皮材积、树皮材积提供了一个新途径。经刺槐、红桦、白桦、山杨验证,也获得同样的结果。 展开更多
关键词 树木 带皮材积 去皮材积 正形数
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正形数系列变化规律的初步研究 被引量:2
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作者 杜纪山 《陕西林业科技》 北大核心 1989年第2期38-43,52,共7页
用陕南、陕北林区16个油松标准地材料,计算各相对高处(0.0,0.02,0.04.0.06,0.08,0.1,0.15,0.2,0.25,0.3,0.4,0.5,0.6,0.7,0.8,0.9)的林分正形数系列样本平均值、标准差和变异系数,初步得出正形数系列在林分内和林分间的变化规律。林分... 用陕南、陕北林区16个油松标准地材料,计算各相对高处(0.0,0.02,0.04.0.06,0.08,0.1,0.15,0.2,0.25,0.3,0.4,0.5,0.6,0.7,0.8,0.9)的林分正形数系列样本平均值、标准差和变异系数,初步得出正形数系列在林分内和林分间的变化规律。林分间带皮正形数系列中稳定的是f_(0.25H),去皮正形数系列中则是 f_(0.30H),林分因子对它们均无显著影响。为便于(?)_(0.5H)和(?)_(0.3H)在实际中应用,给出了两个相对高处直径与胸径之间的回归关系式。 展开更多
关键词 林分测定 正形数系列 变化规律
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马占相思人工实生林立木干形研究 被引量:1
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作者 陆道调 吴保国 +1 位作者 秦武明 戴军 《中南林学院学报》 CAS CSCD 北大核心 2005年第2期21-24,共4页
 为掌握马占相思人工林立木干形变化的规律性,实测431株样木并采用多个干形指标进行了比较研究.结果表明:实验形数变动系数最小,其变动系数为8.55%;实验形数的调查平均值0.3868,比目前区内使用的阔叶树数值(0.4000)呈一定的偏小;正形...  为掌握马占相思人工林立木干形变化的规律性,实测431株样木并采用多个干形指标进行了比较研究.结果表明:实验形数变动系数最小,其变动系数为8.55%;实验形数的调查平均值0.3868,比目前区内使用的阔叶树数值(0.4000)呈一定的偏小;正形数系列中,以1/4树高以下变动系数较小,2/10、1/10树高处形数及胸高形数的变动系数分别是8.69%、10.63%、和9.68%;胸高形数、胸高形率以及树高间呈双曲线关系,相关关系紧密. 展开更多
关键词 森林经理 马占相思 正形数 实验形数 正形数 广西
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广西国营雅长林场细叶云南松干形研究 被引量:8
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作者 陆道调 李宏 《云南林业调查规划设计》 1997年第1期15-20,共6页
本文采用多个干形指标对细叶云南松398株样木进行研究比较,结果表明:(1)以1/4树高正形数变动系数最小而最稳定,其形数原始及调整的平均值分别为0.6983和0.7059。(2)正形率q_(0.7),q_(0.3),q_(0.1)与q_(0.5)呈一元线性相关。(3)正形数f_(... 本文采用多个干形指标对细叶云南松398株样木进行研究比较,结果表明:(1)以1/4树高正形数变动系数最小而最稳定,其形数原始及调整的平均值分别为0.6983和0.7059。(2)正形率q_(0.7),q_(0.3),q_(0.1)与q_(0.5)呈一元线性相关。(3)正形数f_(0.1),f_(0.5)和正形率q_(0.5)呈幂相关。(4)实验形数的初始值和调整值(0.4468,0.4529)均比目前区内使用的数值(0.434)大。 展开更多
关键词 云南松 正形数 形率 树干干形
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四参数柱干比曲线式应用研究
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作者 孟宪法 李悦黎 张方秋 《林业科学研究》 CSCD 北大核心 2001年第1期95-99,共5页
The study involved estimating stem volume, calculating merchantable volume yielding rate and timber assortments volume with four parameter cylinder volume ratio stem profile. The result shows it performs better than S... The study involved estimating stem volume, calculating merchantable volume yielding rate and timber assortments volume with four parameter cylinder volume ratio stem profile. The result shows it performs better than Schumarher Hall at estimating stem volume when the data from Quercus aliena were classified by class. Compared with taper function at calculating merchantable volume yielding rate, four parameter cylinder volume ratio stem profile also performs well with systematic error below 1% and mean square error below 5%. To Pinus tabulaeformis trees, taper function has better accuracy degree than cylinder volume ratio method, but the result is contrary to Q.aliena. When calculating timber assortments volume with four parameter cylinder volume ratio method, systematic error is below 6% and mean square error below 19%. 展开更多
关键词 四参数柱干比曲线式 体积 出材率 规格材出材量 测树学 相对干形 正形数
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云南云龙天池自然保护区云南松干形研究 被引量:1
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作者 袁丽萍 周杰 林玉云 《绿色科技》 2018年第9期125-127,共3页
采用多个干形指标对云南松440株样木进行比较研究,研究结果表明:变动系数最小的正形数是1/4树高,因此其最稳定,f1/4原始数据和调整后的平均值分别为0.6114和0.6176。正形率q0.5与q0.7,q1/4,q0.3之间存在线性的关系。正形率q0.5与正形数... 采用多个干形指标对云南松440株样木进行比较研究,研究结果表明:变动系数最小的正形数是1/4树高,因此其最稳定,f1/4原始数据和调整后的平均值分别为0.6114和0.6176。正形率q0.5与q0.7,q1/4,q0.3之间存在线性的关系。正形率q0.5与正形数呈一元线性函数关系。实验形数的初始值和调整值分别为0.4198,0.4497。 展开更多
关键词 云南松 正形数 形率 树干干形
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Numerical simulation of flow around square cylinder using different low-Reynolds number turbulence models 被引量:3
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作者 张泠 周军莉 +2 位作者 陈晓春 兰丽 张楠 《Journal of Central South University of Technology》 EI 2008年第4期564-568,共5页
ABE-KONDOH-NAGANO,ABID,YANG-SHIH and LAUNDER-SHARMA low-Reynolds number turbulence models were applied to simulating unsteady turbulence flow around a square cylinder in different phases flow field and time-averaged u... ABE-KONDOH-NAGANO,ABID,YANG-SHIH and LAUNDER-SHARMA low-Reynolds number turbulence models were applied to simulating unsteady turbulence flow around a square cylinder in different phases flow field and time-averaged unsteady flow field.Meanwhile,drag and lift coefficients of the four different low-Reynolds number turbulence models were analyzed.The simulated results of YANG-SHIH model are close to the large eddy simulation results and experimental results,and they are significantly better than those of ABE-KONDOH-NAGANO,ABID and LAUNDER-SHARMR models.The modification of the generation of turbulence kinetic energy is the key factor to a successful simulation for YANG-SHIH model,while the correction of the turbulence near the wall has minor influence on the simulation results.For ABE-KONDOH-NAGANO,ABID and LAUNDER-SHARMA models satisfactory simulation results cannot be obtained due to lack of the modification of the generation of turbulence kinetic energy.With the joint force of wall function and the turbulence models with the adoption of corrected swirl stream,flow around a square cylinder can be fully simulated with less grids by the near-wall. 展开更多
关键词 low-Reynolds number turbulence model flow around square cylinder numerical simulation
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Hybrid Strategy of Particle Swarm Optimization and Simulated Annealing for Optimizing Orthomorphisms 被引量:2
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作者 Tong Yan Zhang Huanguo 《China Communications》 SCIE CSCD 2012年第1期49-57,共9页
Orthomorphism on F2^n is a kind of elementary pemmtation with good cryptographic properties. This paper proposes a hybrid strategy of Particle Swarm Optimization (PSO) and Sirrmlated Annealing (SA) for finding ort... Orthomorphism on F2^n is a kind of elementary pemmtation with good cryptographic properties. This paper proposes a hybrid strategy of Particle Swarm Optimization (PSO) and Sirrmlated Annealing (SA) for finding orthomorphisrm with good cryptographic properties. By experiment based on this strategy, we get some orthorrorphisrm on F2^n = 5, 6, 7, 9, 10) with good cryptographic properties in the open document for the first time, and the optirml orthorrrphism on F found in this paper also does better than the one proposed by Feng Dengguo et al. in stream cipher Loiss in difference uniformity, algebraic degree, algebraic irrarnity and corresponding pernmtation polynomial degree. The PSOSA hybrid strategy for optimizing orthomerphism in this paper makes design of orthorrorphisrm with good cryptographic properties automated, efficient and convenient, which proposes a new approach to design orthornorphisrm. 展开更多
关键词 synanetric cryptography orthon-orphism particle swarm optintion simulated annealing
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The Principle of Square Hole Machining and It's Tooling Structure Design
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作者 Jinxia NIU 《International Journal of Technology Management》 2015年第2期7-8,共2页
In order to meet the rapid needs of processing square hole in mechanical equipment, the paper expounds the square hole processing method: planetary wheel method, and analyze the principle of tooling structure and pro... In order to meet the rapid needs of processing square hole in mechanical equipment, the paper expounds the square hole processing method: planetary wheel method, and analyze the principle of tooling structure and process with computer graphics parameters design. The results that, as long as the appropriate parameters, using the above method not only can punch the square hole, can also be processed triangle, the five angle and hexagonal regular polygon holes. The square hole processing method can provide theoretical basis and engineering reliable reference for related engineering and technical personnel. 展开更多
关键词 Abstract: In order to meet the rapid needs of processing square hole in mechanical equipment the paper expounds the square hole processing method: planetary wheel method and analyze the principle of tooling structure and process with computer graphics parameters design. The results that as long as the appropriate parameters using the above method not only can punch the square hole can also be processed triangle the five angle and hexagonal regular polygon holes. The square hole processing method can provide theoretical basis and engineering reliable reference for related engineering and technical personnel. Keywords: Square hole processing Planet wheel Lelo triangle Square hole drilling
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Bias Correction in Wind Direction Forecasting Using the Circular-Circular Regression Method
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作者 XU Jing-Jing HU Fei +4 位作者 XIAO Zi-Niu CHENG Xue-Ling XU Jing-Jing XIAO Zi-Niu CHENG Xue-Ling 《Atmospheric and Oceanic Science Letters》 CSCD 2014年第2期87-91,共5页
Wind direction forecasting plays an important role in wind power prediction and air pollution management. Weather quantities such as temperature, precipitation, and wind speed are linear variables in which traditional... Wind direction forecasting plays an important role in wind power prediction and air pollution management. Weather quantities such as temperature, precipitation, and wind speed are linear variables in which traditional model output statistics and bias correction methods are applied. However, wind direction is an angular variable; therefore, such traditional methods are ineffective for its evaluation. This paper proposes an effective bias correction technique for wind direction forecasting of turbine height from numerical weather prediction models, which is based on a circular-circular regression approach. The technique is applied to a 24-h forecast of 65-m wind directions observed at Yangmeishan wind farm, Yunnan Province, China, which consistently yields improvements in forecast performance parameters such as smaller absolute mean error and stronger similarity in wind rose diagram pattern. 展开更多
关键词 wind direction forecast bias correction circular-circular regression numerical model wind power prediction
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New Formal Solutions of Davey-Stewartson Equation via Combined tanh Function Method with Symmetry Method
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作者 ZHI Hong-Yan ZHANG Hong-Qing 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第4期587-593,共7页
We combine the tanh function method with the symmetry group method to construct new type of solutions of Davey-Stewartson equation and implemente it in a computer algebraic system. As a result, some new types of solut... We combine the tanh function method with the symmetry group method to construct new type of solutions of Davey-Stewartson equation and implemente it in a computer algebraic system. As a result, some new types of solutions are obtained. This method is also applied to other differential equations if the nonlinear evolution equations admit nontrivial one-parameter group of transformation. 展开更多
关键词 tanh function method symmetry group method Davey-Stewartson equation exact solution
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Dual-parameter shaping regularized full waveform inversion in frequency domain 被引量:1
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作者 SUN Ruixue HAN Liguo SUN Eryan 《Global Geology》 2015年第4期258-262,共5页
The regularization contributes to the resolution and stability in geophysical inversion. The authors apply dual-parameter shaping regularization to full waveform inversion, aiming at two points : ( 1 ) improving th... The regularization contributes to the resolution and stability in geophysical inversion. The authors apply dual-parameter shaping regularization to full waveform inversion, aiming at two points : ( 1 ) improving the boundary resolution, and (2) increasing convergence. Firstly, the forward modeling is done, and the inversion is processed with the optimal solution. Compared with classical Tikhonov regularization scheme, the method re fleets better resolution and stronger convergence. Then, Marmousi model is experimented and inversed, and the deep structure has a sharper outline. The phase residual comparison illustrates weaker cycle-slipping. And a choice scheme of parameter is applied in FWI. 展开更多
关键词 dual-parameter REGULARIZATION FWI FREQUENCY-DOMAIN phase-error
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C_(p,q)^(s+α)-forms Solution of _b-equ ation and Its L_(p,q)~s Estimates
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作者 MA Zhong-tai (Department of Mathematics, China Coal Economic College, Yantai 264005, China) 《Chinese Quarterly Journal of Mathematics》 CSCD 2003年第3期234-241,共8页
In this paper, by using holomorphic support f unction of strictly pseudoconvex domain on Stein manifolds and the kernel define d by DEMAILY J P and Laurent Thiebaut, we construct two integral operators T q and S q whi... In this paper, by using holomorphic support f unction of strictly pseudoconvex domain on Stein manifolds and the kernel define d by DEMAILY J P and Laurent Thiebaut, we construct two integral operators T q and S q which are both belong to C s+α p,q-1 (D) and ob tain integral representation of the solution of (p,q)-form b-equation on the boundary of pseudoconvex domain in Stein manifolds and the L s p,q extimates for the solution. 展开更多
关键词 inhomogeneous tangential Cauchy-Riemann equations i ntegral representation of b-solving the kernel of Demaily mand Laurent Thiebaut Chern connection Stein manifold L s p q estim ates
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Introducing Quaternions to Integer Factorisation
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作者 HuiKang Tong 《Journal of Physical Science and Application》 2015年第2期101-107,共7页
The key purpose of this paper is to open up the concepts of the sum of four squares and the algebra of quaternions into the attempts of factoring semiprimes, the product of two prime numbers. However, the application ... The key purpose of this paper is to open up the concepts of the sum of four squares and the algebra of quaternions into the attempts of factoring semiprimes, the product of two prime numbers. However, the application of these concepts here has been clumsy, and would be better explored by those with a more rigorous mathematical background. There may be real immediate implications on some RSA numbers that are slightly larger than a perfect square. 展开更多
关键词 Integer factorisation RSA quatemions sum of four squares euler factorisation method.
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A preliminary research of a falling liquid film on a vertical wavy plane
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作者 SHI Jin-sheng 《Journal of Energy and Power Engineering》 2009年第3期59-62,共4页
The flow of a freely falling liquid film of low Reynolds number down a vertical long periodic sine-shaped wavy plate of small corrugations is researched theoretically. A model based on perturbation method and power se... The flow of a freely falling liquid film of low Reynolds number down a vertical long periodic sine-shaped wavy plate of small corrugations is researched theoretically. A model based on perturbation method and power series is presented. A stream function is introduced into the governing equations and two sets of equations describing the film flow separately at zeroth and first order are developed. The zeroth order equation is solved directly. The first order equations is solved at the leading approximation. Effect of parameters Re, M, λ and ε on the free surface wave of film is discussed. 展开更多
关键词 liquid film flow wavy plate PERTURBATION
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A Categorification of Quantum sl_2
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作者 王娜 王志玺 +1 位作者 吴可 杨紫峰 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第7期37-45,共9页
In this paper, we categorify the algebra Uq(sl2) with the same approach as in [A. Lauda, Adv. Math. (2010), arXiv:math.QA/0803.3662; M. Khovanov, Comm. Algebra 11 (2001) 5033]. The algebra U =Uq(sl2) is obtai... In this paper, we categorify the algebra Uq(sl2) with the same approach as in [A. Lauda, Adv. Math. (2010), arXiv:math.QA/0803.3662; M. Khovanov, Comm. Algebra 11 (2001) 5033]. The algebra U =Uq(sl2) is obtained from Uq(sl2) by adjoining a collection of orthogonal idempotents 1λ,λ ∈ P, in which P is the weight lattice of Uq(sl2). Under such construction the algebra U is decomposed into a direct sum λ∈p 1λ,U1λ. We set the collection of λ∈ P as the objects of the category U, 1-morphisms from λ to λ′ are given by 1λ,U1λ, and 2-morphisms are constructed by some semilinear form defined on U. Hence we get a 2-category u from the algebra Uq(sl2). 展开更多
关键词 quantum affine algebra CATEGORIFICATION
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More on Convering Squares with Squares
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作者 徐常青 丁仁 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2004年第1期70-72,共3页
This paper improves some lower bounds of a function f(x) introduced in the problem of covering squares with squares.
关键词 COVERING SQUARES sequence of closed squares.
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HARMONIC FUNCTIONS ON A COMPLETE NONCOMPACT MANIFOLD WITH ASYMPTOTICALLY NONNEGATIVE CURVATURE 被引量:5
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作者 ZHOUCHAOHUI CHENZHIHUA 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2004年第4期523-532,共10页
The authors prove the space of harmonic functions with polynomial growth of a fixed rate on a complete noncompact Riemannian manifold with asymptotically nonnegative curvature is finite dimensional.
关键词 Harmonic function Asymptotically nonnegative curvature Polynomial growth
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