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From the second gradient operator and second class of integral theorems to Gaussian or spherical mapping invariants 被引量:1
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作者 殷雅俊 吴继业 +1 位作者 黄克智 范钦珊 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2008年第7期855-862,共8页
By combining of the second gradient operator, the second class of integral theorems, the Gaussian-curvature-based integral theorems and the Gaussian (or spherical) mapping, a series of invariants or geometric conser... By combining of the second gradient operator, the second class of integral theorems, the Gaussian-curvature-based integral theorems and the Gaussian (or spherical) mapping, a series of invariants or geometric conservation quantities under Gaussian (or spherical) mapping are revealed. From these mapping invariants important transformations between original curved surface and the spherical surface are derived. The potential applications of these invariants and transformations to geometry are discussed 展开更多
关键词 the second gradient operator integral theorem Gaussian curvature Gaussian (or spherical) mapping mapping invariant
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Color Edge Detection Using Multidirectional Sobel Filter and Fuzzy Fusion 被引量:1
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作者 Slim Ben Chaabane Anas Bushnag 《Computers, Materials & Continua》 SCIE EI 2023年第2期2839-2852,共14页
A new model is proposed in this paper on color edge detection that uses the second derivative operators and data fusion mechanism.The secondorder neighborhood shows the connection between the current pixel and the sur... A new model is proposed in this paper on color edge detection that uses the second derivative operators and data fusion mechanism.The secondorder neighborhood shows the connection between the current pixel and the surroundings of this pixel.This connection is for each RGB component color of the input image.Once the image edges are detected for the three primary colors:red,green,and blue,these colors are merged using the combination rule.Then,the final decision is applied to obtain the segmentation.This process allows different data sources to be combined,which is essential to improve the image information quality and have an optimal image segmentation.Finally,the segmentation results of the proposed model are validated.Moreover,the classification accuracy of the tested data is assessed,and a comparison with other current models is conducted.The comparison results show that the proposed model outperforms the existing models in image segmentation. 展开更多
关键词 SEGMENTATION edge detection second derivative operators data fusion technique fuzzy fusion CLASSIFICATION
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基于文献计量分析的二语口语能力构念研究 被引量:1
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作者 王婷婷 周丹丹 《西安外国语大学学报》 CSSCI 北大核心 2024年第4期49-55,共7页
本文结合文献计量法和系统性综述法,梳理了以往研究中对二语口语能力构念的界定,并从子技能、认知过程和影响因素三个角度对199篇国内外语言学核心期刊的实证研究中对该构念的操作化定义进行了归纳分析。研究发现:二语口语能力构念的涵... 本文结合文献计量法和系统性综述法,梳理了以往研究中对二语口语能力构念的界定,并从子技能、认知过程和影响因素三个角度对199篇国内外语言学核心期刊的实证研究中对该构念的操作化定义进行了归纳分析。研究发现:二语口语能力构念的涵盖范围有所拓展,现有实证研究中对二语口语能力的操作化定义逐渐具体化、可测量性更强。不过,现有研究仍存在如下不足:(1)缺乏对口语产出过程的探究;(2)对各个二语口语子技能的研究不均衡,对内容、语篇和语用能力等维度的研究有待扩充;(3)对影响二语产出的各种因素的交互作用的比较欠缺。本文最后提出了一个多元二语口语能力框架,并探讨了未来研究的方向。 展开更多
关键词 二语口语能力 构念界定 构念操作化定义 文献计量分析 系统性回顾法
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Fractional integration associated with second order divergence operators on R^n 被引量:3
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作者 邓东皋 颜立新 《Science China Mathematics》 SCIE 2003年第3期355-363,共9页
The classical Hardy-Littlewood-Sobolev theorems for Riesz potentials (?Δ)?α/2 are extended to the generalised fractional integrals L –α/2 for 0 < α < n, where L=?div A? is a uniformly complex elliptic opera... The classical Hardy-Littlewood-Sobolev theorems for Riesz potentials (?Δ)?α/2 are extended to the generalised fractional integrals L –α/2 for 0 < α < n, where L=?div A? is a uniformly complex elliptic operator with bounded measurable coefficients in ?n. 展开更多
关键词 fractional integral second order divergence operator SEMIGROUP Hardy- Littlewood- Sobolev theorem
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On a Class of Second Order Partial Differential Operators of Non-principal Type
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作者 黄玉民 《Acta Mathematica Sinica,English Series》 SCIE 1985年第1期35-40,共6页
§1.IntroductionThis paper deals with linear partial differential operators with real principalsymbol.Let P(x,D)be such an operator of mth order with C~∞ coefficients definedin an open subset Ω of R^n and p_m(x,... §1.IntroductionThis paper deals with linear partial differential operators with real principalsymbol.Let P(x,D)be such an operator of mth order with C~∞ coefficients definedin an open subset Ω of R^n and p_m(x,ξ)be its principal symbol.According to thedefinition given by Duistermaat and Hmander(see[1]),P(x,D)is called ofprincipal type at x^0 ∈Ω if for any ξ∈R^n\0 satisfying p_m(x^0,ξ)=0,x=x^0 is not theprojection in Ω of the bicharacteristic strip of P(x,D)through(x^0,ξ).Under thiscondition,they proved that there exists a neighborhood U of x^0,U,such that forany real number s, 展开更多
关键词 On a Class of second Order Partial Differential Operators of Non-principal Type
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Invariants for Parallel Mapping 被引量:1
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作者 殷雅俊 吴继业 +1 位作者 范钦珊 黄克智 《Tsinghua Science and Technology》 SCIE EI CAS 2009年第5期646-654,共9页
This paper analyzes the geometric quantities that remain unchanged during parallel mapping (i.e., mapping from a reference curved surface to a parallel surface with identical normal direction). The second gradient o... This paper analyzes the geometric quantities that remain unchanged during parallel mapping (i.e., mapping from a reference curved surface to a parallel surface with identical normal direction). The second gradient operator, the second class of integral theorems, the Gauss-curvature-based integral theorems, and the core property of parallel mapping are used to derive a series of parallel mapping invariants or geometrically conserved quantities. These include not only local mapping invariants but also global mapping invafiants found to exist both in a curved surface and along curves on the curved surface. The parallel mapping invariants are used to identify important transformations between the reference surface and parallel surfaces. These mapping invariants and transformations have potential applications in geometry, physics, biomechanics, and mechanics in which various dynamic processes occur along or between parallel surfaces. 展开更多
关键词 second gradient operator second class of integral theorem parallel mapping INVARIANTS TRANSFORMATIONS
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