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SECOND ORDER EFFECTS IN AN ELASTIC HALF-SPACE ACTED UPON BY A NON-UNIFORM NORMAL LOAD
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作者 刘又文 郭建林 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1994年第12期1149-1168,共16页
A closed form solution to the second order elasticity problem ,when an isotropiccompressible elastic half-space undergoes a deformation owing to a non-uniformlydistributed normal load,is presented,The method of integr... A closed form solution to the second order elasticity problem ,when an isotropiccompressible elastic half-space undergoes a deformation owing to a non-uniformlydistributed normal load,is presented,The method of integral transform is employedand the case when loading is distributed,in accordance with Hertz'x law ,is discussed.The limiting solution for incompressible isotropic elastic material is also derived.Numerical calculations for the second order elastic material for the displacement and the normal stress in the z-direction are carried out .It is found that,in comparison to the linear elastic case,the displacement increases and the normal stress decreases in the second order elastic material. 展开更多
关键词 elastic half-space. second order elasticity problem. integraltransform
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Some Results on the Space of Bounded Second Variation Functions in the Sense of Shiba
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作者 Liliana Pérez Ebner Pineda Luz Rodríguez 《Advances in Pure Mathematics》 2020年第5期245-258,共14页
In this paper, we study the structure of the space of functions of bounded second variation in the sense of Shiba;an integral representation theorem is also proved and necessary conditions are given for that the space... In this paper, we study the structure of the space of functions of bounded second variation in the sense of Shiba;an integral representation theorem is also proved and necessary conditions are given for that the space be closed under composition of functions. Another significant result is the proof that this space of bounded second variation in the sense of Shiba is a Banach algebra, which is not immediate as it happens in other spaces of generalized bounded variation. 展开更多
关键词 Functional Analysis BOUNDED VARIATION second BOUNDED VARIATION BANACH space
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THE ILLUSTRATION CALCULATIONS OF SECOND ORDER EFFECTS IN ELASTIC HALF-SPACE ACTED UPON BY A NON-UNIFORM SHEAR LOAD
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作者 刘又文 郭建林 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1997年第6期563-570,共8页
This paper is a continuation of [1]. An example is discussed in derail to illustrate the second order effects. Numerical calculations for the second order elastic material for the z-direction displacement and the stre... This paper is a continuation of [1]. An example is discussed in derail to illustrate the second order effects. Numerical calculations for the second order elastic material for the z-direction displacement and the stress t(rz) are carried out. It is found that the second order effect is to reduce z-direction displacement and to decrease t(rz)inside the circle but to increase its value outside the circle. 展开更多
关键词 elastic half-space shear load second order elasticity effects integral transform
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THE GENERAL SOLUTION OF SECOND ORDER EFFECTS IN ELASTIC HALF-SPACE ACTED UPON BY A NON-UNIFORM SHEAR LOAD
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作者 刘又文 郭建林 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1997年第4期365-380,共16页
This paper is a continuation of [1]. A closed form solution to the second order elasticity problem, when an isotropic compressible elastic half-space undergoes a deformation owing to a non-uniformly distributed shear ... This paper is a continuation of [1]. A closed form solution to the second order elasticity problem, when an isotropic compressible elastic half-space undergoes a deformation owing to a non-uniformly distributed shear load, is presented. The method of integral transform is employed to determine the solutions. 展开更多
关键词 elastic half-space shear load second order elasticity effects integral transform
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SOLVABILITY IN HARDY SPACE FOR SECOND ORDER ELLIPTIC EQUATIONS
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作者 Yongzhong Sun Weiyi Su 《Analysis in Theory and Applications》 2009年第4期355-368,共14页
We obtain a priori estimates and solvability in Hardy type space in a bounded domain of Rn for second order elliptic equations with coefficients of limited smoothness. Such a result can be served as an endpoint case o... We obtain a priori estimates and solvability in Hardy type space in a bounded domain of Rn for second order elliptic equations with coefficients of limited smoothness. Such a result can be served as an endpoint case of the classical LP(1 〈 p 〈 ∞) theory for second order elliptic equations. Our approach is based on a standard technique of perturbation rather than that of integral representation formula. 展开更多
关键词 Hardy space in a bounded domain second order elliptic equation a prioriestimate SOLVABILITY
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Actively Promoting Regional Space Cooperation——Vice Administrator, Loan Enjie headed a delegation to attend the Second Asia-Pacific Conference on Multilateral Cooperation in Space Technology and Applications
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作者 Zhang Lihui 《Aerospace China》 1995年第1期14-15,共2页
A Chinese delegation of 24 persons headed by Mr. Luan Enjie, Vice Administrator of China National Space Administration (CNSA) attended the Second Asia-Pacific Conference on Multilateral Cooperation in Space Technology... A Chinese delegation of 24 persons headed by Mr. Luan Enjie, Vice Administrator of China National Space Administration (CNSA) attended the Second Asia-Pacific Conference on Multilateral Cooperation in Space Technology and Applications held at Islamabad, the Capital of Pakistan from April 22 to 26, 1995. Following the First AsiaPacific Workshop held in Beijing in December, 1992, and the First Asia-Pacific Conference on Multilateral Cooperation in 展开更多
关键词 Asia Loan Enjie headed a delegation to attend the second Asia-Pacific Conference on Multilateral Cooperation in space Technology and Applications Vice Administrator Actively Promoting Regional space Cooperation
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Making Cooperation in Space for Better Future Summary of the Keynote Speech at the Second Asia Pacific Conference on Multilateral Cooperation in Space Technology and Applications
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作者 Luan Enjie,Vice Administrator of China National Space Administration 《Aerospace China》 1995年第1期4-5,共2页
Since the Asia Pacific Workshop on Multilateral Cooperation in Space Technology and Applications was held in Beijing in December, 1992, the preparatory committee for Asia-Pacific Space Cooperation Mechanism and the Li... Since the Asia Pacific Workshop on Multilateral Cooperation in Space Technology and Applications was held in Beijing in December, 1992, the preparatory committee for Asia-Pacific Space Cooperation Mechanism and the Liaison Committee for AP-MC-STA have done many fruitful works. Thanks to the First Asia Pacific Conference on Multilateral Cooperation in Space Tech- 展开更多
关键词 Asia Making Cooperation in space for Better Future Summary of the Keynote Speech at the second Asia Pacific Conference on Multilateral Cooperation in space Technology and Applications Keynote
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“Second Life”中的图书馆2.0 被引量:17
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作者 杨丰全 周凤飞 任静 《图书与情报》 CSSCI 2007年第6期13-15,139,共4页
文章简要介绍了Second life的应用情况,并主要对在Second life中建立和延伸图书馆服务的意义和国外的应用发展状况进行了阐述。
关键词 第二生命 虚拟空间 图书馆2.0
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Characterizations of Sobolev spaces in Euclidean spaces and Heisenberg groups 被引量:3
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作者 CUI Xiao-yue LAM Nguyen LU Guo-zhen 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2013年第4期531-547,共17页
Recently, many new features of Sobolev spaces W k,p ?RN ? were studied in [4-6, 32]. This paper is devoted to giving a brief review of some known characterizations of Sobolev spaces in Euclidean spaces and describin... Recently, many new features of Sobolev spaces W k,p ?RN ? were studied in [4-6, 32]. This paper is devoted to giving a brief review of some known characterizations of Sobolev spaces in Euclidean spaces and describing our recent study of new characterizations of Sobolev spaces on both Heisenberg groups and Euclidean spaces obtained in [12] and [13] and outlining their proofs. Our results extend those characterizations of first order Sobolev spaces in [32] to the Heisenberg group setting. Moreover, our theorems also provide diff erent characterizations for the second order Sobolev spaces in Euclidean spaces from those in [4, 5]. 展开更多
关键词 characterization of Sobelev spaces Folland-Stein space Poincar′e inequalities Heisenberg group second order Sobolev space
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Approximate Controllability of Second-Order Neutral Stochastic Differential Equations with Infinite Delay and Poisson Jumps 被引量:4
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作者 PALANISAMY Muthukumar CHINNATHAMBI Rajivganthi 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第5期1033-1048,共16页
The modelling of risky asset by stochastic processes with continuous paths, based on Brow- nian motions, suffers from several defects. First, the path continuity assumption does not seem reason- able in view of the po... The modelling of risky asset by stochastic processes with continuous paths, based on Brow- nian motions, suffers from several defects. First, the path continuity assumption does not seem reason- able in view of the possibility of sudden price variations (jumps) resulting of market crashes. A solution is to use stochastic processes with jumps, that will account for sudden variations of the asset prices. On the other hand, such jump models are generally based on the Poisson random measure. Many popular economic and financial models described by stochastic differential equations with Poisson jumps. This paper deals with the approximate controllability of a class of second-order neutral stochastic differential equations with infinite delay and Poisson jumps. By using the cosine family of operators, stochastic analysis techniques, a new set of sufficient conditions are derived for the approximate controllability of the above control system. An example is provided to illustrate the obtained theory. 展开更多
关键词 Approximate controllability Hilbert space Poisson jumps second-order neutral stochas-tic differential equations semigroup theory.
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DYNAMIC VARIATION OF NITROGEN CONTENT IN THE SECOND SONGHUA RIVER
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作者 刘景双 于君宝 《Chinese Geographical Science》 SCIE CSCD 1999年第4期81-85,共5页
The space time variation laws of nitrogen content in different river sections, water periods and years in the Second Songhua River in China is described in detail. The results show that there is direct relation betwee... The space time variation laws of nitrogen content in different river sections, water periods and years in the Second Songhua River in China is described in detail. The results show that there is direct relation between the nitrogen content variation in river water and that in wastewater from cities and runoff water of both banks of the river. Nitrate and nitrite contents in water in flood period are higher than that in mid and low water periods. In flood period, nitrate content in water increases gradually with the extension of river section, ammonia content in polluted river section is higher than that in unpolluted river section. Nitrate and nitrite contents in water in the flood, mid and low water periods from 1985 to 1989 were slightly higher than that from 1980 to 1984 and from 1990 to 1994, ammonia content in water increased annually. 展开更多
关键词 NITROGEN CONTENT space time VARIATION LAW the second Songhua RIVER
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COMPLETE SPACE-LIKE SUBMANIFOLDS IN LOCALLY SYMMETRIC SEMI-DEFINITE SPACES
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作者 XuSenlin ChenDongmei 《Analysis in Theory and Applications》 2004年第4期383-390,共8页
The purpose of this paper is to study complete space-like submanifolds with parallel mean curvature vector and flat normal bundle in a locally symmetric semi-defnite space satisfying some curvature conditions. We firs... The purpose of this paper is to study complete space-like submanifolds with parallel mean curvature vector and flat normal bundle in a locally symmetric semi-defnite space satisfying some curvature conditions. We first give an optimal estimate of the Laplacian of the squared norm of the second fundamental form for such submanifold. Furthermore, the totally umbilical submanifolds are characterized. 展开更多
关键词 space-like submanifolds constant mean curvature flat normal bundle second fundamental form locally symmetric semi-definite space
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传承、探索与发展空间:2020年以来国内动态系统理论视域下的二语习得研究
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作者 梁桃英 杨艺媛 《宜春学院学报》 2025年第4期88-94,共7页
近几年来,我国动态系统理论视域下的二语习得研究显现出新的研究趋向和发展态势。基于2020年1月到2024年6月期间发表于CSSCI期刊和中文核心期刊的相关研究成果的梳理和分析,可知实证研究几乎是一枝独秀,占据了绝对主导的地位,从而改变... 近几年来,我国动态系统理论视域下的二语习得研究显现出新的研究趋向和发展态势。基于2020年1月到2024年6月期间发表于CSSCI期刊和中文核心期刊的相关研究成果的梳理和分析,可知实证研究几乎是一枝独秀,占据了绝对主导的地位,从而改变了以往的研究格局。分而言之,理论研究颇为寂寥,许多研究主题未能继续得到探讨;实证研究承续了此前的研究兴趣,又积极探索,拓展新境,但在研究主题、研究对象、研究方法与研究设计等方面仍存在诸多局限,尚待后续研究努力予以突破。 展开更多
关键词 动态系统理论 二语习得研究 探索 发展空间
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Spacem占位器专用骨水泥联合敏感抗生素在全膝关节置换术后感染二期翻修中的应用效果
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作者 宋维 杨武镠 +1 位作者 刘泉 李洋 《世界复合医学(中英文)》 2024年第9期120-123,共4页
目的探讨全膝关节置换术后感染二期翻修中应用敏感抗生素联合Spacem占位器专用骨水泥治疗的效果。方法选择2022年1月—2023年12月黔西市人民医院收治的60例全膝关节置换术后感染患者作为研究对象,根据治疗方法的不同将其分为对照组和观... 目的探讨全膝关节置换术后感染二期翻修中应用敏感抗生素联合Spacem占位器专用骨水泥治疗的效果。方法选择2022年1月—2023年12月黔西市人民医院收治的60例全膝关节置换术后感染患者作为研究对象,根据治疗方法的不同将其分为对照组和观察组,各30例。对照组采用传统方法治疗,观察组采用Spacem占位器专用骨水泥联合敏感抗生素治疗。比较两组炎症指标、临床疗效和术后并发症总发生率。结果治疗前,两组患者白细胞计数、中性粒细胞比例对比,差异无统计学意义(P均>0.05)。治疗后,观察组患者白细胞计数为(5.74±0.83)×10~9/L,中性粒细胞比例为(42.34±2.05)%,低于对照组的(12.01±1.26)×10~9/L、(68.11±2.27)%,差异有统计学意义(t=8.254、9.361,P均<0.05)。观察组治疗总有效率高于对照组,术后并发症总发生率低于对照组,差异有统计学意义(P均<0.05)。结论Spacem占位器专用骨水泥联合敏感抗生素在全膝关节置换术后感染二期翻修中的应用效果显著,且安全性高。 展开更多
关键词 全膝关节置换术后感染 spacem占位器 骨水泥 敏感抗生素 二期翻修
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We Live on a Small Space Comet: The Third Extraordinary Motion of Earth towards the North Pole and Its Various Effects
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作者 Walid Nabil 《Advances in Aerospace Science and Technology》 2023年第3期21-33,共13页
The idea of research started with a crazy imaginary theory in the field of astrogeography, saying: We often taught ourselves and then convinced the students that the planet Earth moves despite not feeling the vibratio... The idea of research started with a crazy imaginary theory in the field of astrogeography, saying: We often taught ourselves and then convinced the students that the planet Earth moves despite not feeling the vibrations of traffic, and we listed successive scientific confirmations to indicate the rotation of the planet in a regular movement around its axis once every 24 hours, and it is running in another second movement around the sun once every 365¼ days, so are they only two movements, no more?! Is it possible for him to run at a regular speed in an additional direction? 展开更多
关键词 The Third Additional Regular Movement of the Planet Earth towards the North Pole The Movement of the Planet Earth in space The Spiral Path of the Earth The Speed of the Planet 1.3 Kilometers per second The Planet Earth A Small space Comet
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铁路增建二线工程隧道合理线间距研究
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作者 杨克文 于晨昀 +1 位作者 杨昕睿 李鹏飞 《铁道标准设计》 北大核心 2025年第10期103-110,149,共9页
随着交通运输需求的提高,现有线路的运能难以满足运营要求,需开展增建二线工程进行扩能改造。作为隧道力学行为的主要影响因素,确定合理净距尤为重要。因此,对铁路增建二线工程隧道合理线间距展开研究,为增二线隧道净距设计提供依据和... 随着交通运输需求的提高,现有线路的运能难以满足运营要求,需开展增建二线工程进行扩能改造。作为隧道力学行为的主要影响因素,确定合理净距尤为重要。因此,对铁路增建二线工程隧道合理线间距展开研究,为增二线隧道净距设计提供依据和量化标准。考虑到目前在铁路增二线工程方面缺乏针对性研究,首先对相似工程进行调研作为参考,并建立既有隧道变形、劣化情况等控制标准进一步指导合理线间距取值。基于偏压荷载模型对新建明挖隧道展开分析,建立以新建明挖隧道基坑边坡为联系的隧道净距与既有隧道外侧拱肩山体覆盖厚度的对应关系。之后建立二维平面模型进行数值分析,探究不同间跨比工况下地表变形、既有隧道拱脚差异沉降的变化规律和塑性区发展情况。模拟结果表明,Ⅴ级围岩软岩条件下,随间跨比增大,地表沉降和既有隧道拱脚差异沉降曲线均显著减小,且间跨比>2.5时,曲线趋于稳定;两隧道塑性区先贯通后分离,间跨比等于1.5时首次分离,后逐渐减小,间跨比>2.5时两塑性区形态基本稳定。将沉降曲线斜率和塑性区形态保持稳定处作为评定标准,同时结合实际工程需求和地质情况,最终提出Ⅴ级围岩软岩对应隧道净距合理取值范围为(2.0~3.0)B(B为隧道开挖断面宽度)。综合分析下,最终提出一般暗挖和明挖段增建二线工程的隧道净距建议值。 展开更多
关键词 铁路隧道 增建二线 合理线间距 数值模拟 明挖隧道 加固措施
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苏北盆地溱潼凹陷阜二段页岩油储层成岩作用及孔隙演化特征——以QY1井为例
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作者 夏威 蔡潇 +2 位作者 刘玉霞 李辉 朱一川 《东北石油大学学报》 北大核心 2025年第6期98-111,I0017,I0018,共16页
分析储层的孔隙发育特征及演化规律有助于明确油气富集规律和运移机理。对于苏北盆地溱潼凹陷QY1井岩心样品,采用矿物学、地球化学、热模拟等方法,研究储层的成岩作用阶段及类型、储集空间识别与划分,分析孔隙系统演化规律。结果表明:... 分析储层的孔隙发育特征及演化规律有助于明确油气富集规律和运移机理。对于苏北盆地溱潼凹陷QY1井岩心样品,采用矿物学、地球化学、热模拟等方法,研究储层的成岩作用阶段及类型、储集空间识别与划分,分析孔隙系统演化规律。结果表明:研究区页岩主要由长英质、碳酸盐和黏土等矿物组成,总有机碳质量分数平均为1.33%,镜质体反射率为0.88%~1.24%,孔隙度平均为3.38%;层系储集空间分为裂缝和孔隙两大类,细分为10个亚类,储层处于中成岩演化阶段,经历压实、溶蚀、胶结、重结晶、交代等成岩作用,重结晶和溶蚀作用可形成粒间孔、溶蚀孔等,有利于储集空间发育;黏土矿物晶间缝和石英粒间孔对储层渗流能力起积极改善作用,随热演化程度变化,储集空间整体向增大的方向演化,成熟阶段储集空间以溶蚀孔为主,随成熟度升高,有机孔发育,且孔隙连通性逐渐改善,油气在储层内发生运移。该结果为苏北盆地页岩油储层富集机制和油气运移模式研究提供依据。 展开更多
关键词 成岩作用 储集空间 孔隙演化特征 页岩油 阜宁组二段 溱潼凹陷 苏北盆地
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安全约束下空间机器人的全局固定时间紧急控制
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作者 雷荣华 侯海良 付晓东 《中国安全科学学报》 北大核心 2025年第12期103-110,共8页
为解决具有时间约束和输出约束的不确定空间机器人(USR)系统安全约束问题,采用一种二阶滑模全局固定时间紧急控制方法,应用动量守恒定理和拉格朗日法建立USR的动力学模型;为实现安全输出目标,引入障碍Lyapunov函数,将系统误差限定在预... 为解决具有时间约束和输出约束的不确定空间机器人(USR)系统安全约束问题,采用一种二阶滑模全局固定时间紧急控制方法,应用动量守恒定理和拉格朗日法建立USR的动力学模型;为实现安全输出目标,引入障碍Lyapunov函数,将系统误差限定在预设范围;在此基础上,估计系统不确定项的上界,并进一步考虑系统时间约束,借助加幂积分技术构造一种二阶滑模全局固定时间紧急控制器(GFEC)。结果表明:本文方法的控制精度均显著优于未考虑输出约束的终端滑模固定时间控制器,其均方根误差(RMSE)分别降低55.71%和56.45%,且能够确保USR系统的输出被严格限制在预设安全边界内,表明所设计控制方法跟踪性能的优越性。 展开更多
关键词 安全约束 不确定空间机器人(USR) 二阶滑模 固定时间 紧急控制 输出约束
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拟复射影空间的Kahler迷向子流形
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作者 石玉鑫 《数学杂志》 2025年第5期445-455,共11页
本文研究了拟复射影空间的Kahler迷向子流形Pinching问题,利用活动标架法,得到了关于第二基本形式、截面曲率下界,Ricci曲率下界的Pinching定理,将Pinching常数和外围空间都进行了推广.
关键词 拟复射影空间 迷向子流形 第二基本形式 Kahler子流形
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Sasakian空间形式中Legendrian子流形的不等式
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作者 吴培芳 李凤江 《楚雄师范学院学报》 2025年第3期104-108,共5页
基于子流形的基本公式,本文研究了2n+1维Sasakian空间形式中的n维Legendrian子流形,得到了一个关于Legendrian子流形第二基本形式和平均曲率向量的不等式,并进一步通过经典K. Yano公式,建立了一个关于n维紧致Legendrian子流形的积分不... 基于子流形的基本公式,本文研究了2n+1维Sasakian空间形式中的n维Legendrian子流形,得到了一个关于Legendrian子流形第二基本形式和平均曲率向量的不等式,并进一步通过经典K. Yano公式,建立了一个关于n维紧致Legendrian子流形的积分不等式。 展开更多
关键词 SASAKIAN空间形式 Legendrian子流形 第二基本形式 平均曲率向量
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