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Finite-time stability with respect to a closed invariant set for a class of discontinuous systems 被引量:3
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作者 程桂芳 慕小武 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第8期1069-1075,共7页
This paper discusses the problem of finite-time stability with respect to a closed, but not necessarily compact, invariant set for a class of nonlinear systems with discontinuous right-hand sides in the sense of the F... This paper discusses the problem of finite-time stability with respect to a closed, but not necessarily compact, invariant set for a class of nonlinear systems with discontinuous right-hand sides in the sense of the Filippov solutions. When the Lyapunov function is Lipschitz continuous and regular, the Lyapunov theorem on finite-time stability with respect to a closed invariant set is presented. 展开更多
关键词 Filippov solution closed invariant set finite-time stability discontinuous system
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On the Decomposition of a Bounded Closed Interval of the Real Line into Closed Sets
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作者 Edgar A. Cohen 《Advances in Pure Mathematics》 2013年第4期405-408,共4页
It has been shown by Sierpinski that a compact, Hausdorff, connected topological space (otherwise known as a continuum) cannot be decomposed into either a finite number of two or more disjoint, nonempty, closed sets o... It has been shown by Sierpinski that a compact, Hausdorff, connected topological space (otherwise known as a continuum) cannot be decomposed into either a finite number of two or more disjoint, nonempty, closed sets or a countably infinite family of such sets. In particular, for a closed interval of the real line endowed with the usual topology, we see that we cannot partition it into a countably infinite number of disjoint, nonempty closed sets. On the positive side, however, one can certainly express such an interval as a union of c disjoint closed sets, where c is the cardinality of the real line. For example, a closed interval is surely the union of its points, each set consisting of a single point being closed. Surprisingly enough, except for a set of Lebesgue measure 0, these closed sets can be chosen to be perfect sets, i.e., closed sets every point of which is an accumulation point. They even turn out to be nowhere dense (containing no intervals). Such nowhere dense, perfect sets are sometimes called Cantor sets. 展开更多
关键词 CANTOR setS CARDINALITY DISJOINT closed setS DYADIC Representation INTERLACING DYADIC Expansions Generators of setS Nowhere Dense
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Remarks on (1, 2)^*-Generalized Closed Sets with Respect to an Ideal Bitopological Space
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作者 H. S. Al-Saadi Takashi Noiri 《Journal of Mathematics and System Science》 2012年第6期348-351,共4页
In this paper, the authors introduce and study the concept of (1, 2)^*-generalized closed sets with respect to an ideal in a bitopological space. Also, some characterizations and applications of(1, 2)^*-generali... In this paper, the authors introduce and study the concept of (1, 2)^*-generalized closed sets with respect to an ideal in a bitopological space. Also, some characterizations and applications of(1, 2)^*-generalized closed sets are given. 展开更多
关键词 Bitopological space (1 2)^*-generalized closed set topological ideal.
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Intuitionistic Fuzzy α-Generalized Closed Sets in Terms of Minimal Structure Spaces
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作者 Mani Parimala Sivaraman Murali 《Circuits and Systems》 2016年第8期1486-1491,共6页
In this paper, we introduce the notion of intuitionistic fuzzy α-generalized closed sets in intuitionistic fuzzy minimal structure spaces and investigate some of their properties. Further, we introduce and study the ... In this paper, we introduce the notion of intuitionistic fuzzy α-generalized closed sets in intuitionistic fuzzy minimal structure spaces and investigate some of their properties. Further, we introduce and study the concept of intuitionistic fuzzy α-generalized minimal continuous functions. 展开更多
关键词 Intuitionistic Fuzzy Topology Intuitionistic Fuzzy α-Generalized closed set Intuitionistic Fuzzy α-Generalized Continuous Function Intuitionistic Fuzzy α-Generalized Continuous Mappings
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用变异FP-树改进CLOSET算法
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作者 刘迎意 吴春旭 沈陵峰 《计算机仿真》 CSCD 北大核心 2010年第3期98-101,共4页
频繁闭项集提供了频繁项集的一种完整、最小表示,对频繁闭项集的挖掘是近年来数据挖掘领域研究的热点,研究人员从不同角度对算法改进以提高算法的效率。基于频繁项集中共生项集的性质,提出无须进行子集检查的频繁闭项集挖掘方法,并设计... 频繁闭项集提供了频繁项集的一种完整、最小表示,对频繁闭项集的挖掘是近年来数据挖掘领域研究的热点,研究人员从不同角度对算法改进以提高算法的效率。基于频繁项集中共生项集的性质,提出无须进行子集检查的频繁闭项集挖掘方法,并设计一种变异的FP-树结构,利用FP-树结构来存储结点共生项集信息,以改进CLOSET算法,算法无须遍历结果集进行闭合性检查。实验表明,在支持度阈值减小,结果集变大时,改进算法的时间增长率比原有算法小。 展开更多
关键词 数据挖掘 频繁闭项集 算法改进
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An Implanted Closed-loop Chip System for Heart Rate Control:System Design and Effects in Conscious Rats 被引量:3
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作者 Yuxuan Zhou Yuan Yuan +4 位作者 Juan Gao Ling Yang Feng Zhang Guoqing Zhu Xingya Gao 《The Journal of Biomedical Research》 CAS 2010年第2期107-114,共8页
Objective: To evaluate the efficiency of an implanted chip system for the control of heart rate (HR). Methods: The HR was recorded in six conscious Sprague-Dawley (SD) rats. An implanted chip system was designed... Objective: To evaluate the efficiency of an implanted chip system for the control of heart rate (HR). Methods: The HR was recorded in six conscious Sprague-Dawley (SD) rats. An implanted chip system was designed to regulate the HR by stimulating the right cervical vagus nerve according to the feedback of real time HR. Each rat was subjected to 30-min regulation and 30-min recovery. The change of HR during the regulation period was compared with the control. The ECG was recorded during the experiment for 24 h. Results: The ECG signals were successfully recorded during the experiment. The HR was significantly decreased during the period of regulation compared with control (-79.3 ± 34.5, P 〈 0.01, n = 6) and then recovered to normal after regulation. Conclusion: The described implanted chip system can regulate the HR to a designated set point. 展开更多
关键词 closed-loop regulation implanted chip system set point heart rate vagus nerve stimulation Remote-controlled animal
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Rough similarity degree and rough close degree in rough fuzzy sets and the applications
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作者 Li Jian Xu Xiaojing Shi Kaiquan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第5期945-951,共7页
Based on rough similarity degree of rough sets and close degree of fuzzy sets, the definitions of rough similarity degree and rough close degree of rough fuzzy sets are given, which can be used to measure the similar ... Based on rough similarity degree of rough sets and close degree of fuzzy sets, the definitions of rough similarity degree and rough close degree of rough fuzzy sets are given, which can be used to measure the similar degree between two rough fuzzy sets. The properties and theorems are listed. Using the two new measures, the method of clustering in the rough fuzzy system can be obtained. After clustering, the new fuzzy sample can be recognized by the principle of maximal similarity degree. 展开更多
关键词 rough fuzzy set rough similarity degree rough close degree CLUSTERING recognition of rough pattern maximal similarity degree principle.
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Theorems of Helly's Type for Partially-closed Half-spaces
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作者 Liu Jian-Guo Guo Qi 《Communications in Mathematical Research》 CSCD 2018年第2期117-124,共8页
In this article, under quite weaker conditions, theorems of Helly’s type for(not necessarily finite) family of partially closed half-spaces are presented in both analytic and geometric forms. Examples are also provid... In this article, under quite weaker conditions, theorems of Helly’s type for(not necessarily finite) family of partially closed half-spaces are presented in both analytic and geometric forms. Examples are also provided to show that these conditions cannot be omitted in general. 展开更多
关键词 Helly's theorem partially-closed half-space affine function convex set
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商业会展综合建筑中喷头选择及设置问题探讨
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作者 李国顺 《工程建设与设计》 2026年第1期66-68,共3页
以苏州青苔国际工业设计村三期会展项目为例,从喷头类型、喷头动作温度、喷头结构形式和安装方式、喷头出水口径及喷头响应时间等方面介绍了喷头的选择方法。针对建筑内部场所功能区不同的特点,介绍了场所内喷头设置情况,着重分析了建... 以苏州青苔国际工业设计村三期会展项目为例,从喷头类型、喷头动作温度、喷头结构形式和安装方式、喷头出水口径及喷头响应时间等方面介绍了喷头的选择方法。针对建筑内部场所功能区不同的特点,介绍了场所内喷头设置情况,着重分析了建筑内部特殊区域喷头的设置要求,强调结合建筑造型、净空高度及危险等级选择合适的喷头设置方案。 展开更多
关键词 综合建筑 喷头 湿式系统 闭式系统 设置场所
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On <i>M</i>-Asymmetric Semi-Open Sets and Semicontinuous Multifunctions in Bitopological Spaces 被引量:2
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作者 Levy K. Matindih Edwin Moyo 《Advances in Pure Mathematics》 2021年第4期218-236,共19页
The purpose of this paper is to introduce the notions of m-asymmetric semiopen sets and M-asymmetric semicontinuous multifunctions defined between asymmetric sets satisfying certain minimal conditions in the framework... The purpose of this paper is to introduce the notions of m-asymmetric semiopen sets and M-asymmetric semicontinuous multifunctions defined between asymmetric sets satisfying certain minimal conditions in the framework of bitopological spaces. Some new characterizations of m-asymmetric semiopen sets and M-asymmetric semicontinuous multifunctions will be investigated and several fundamental properties will be obtained. 展开更多
关键词 m-Spaces m-Semiasymmetric Open and closed sets Upper and Lower M-Asymmetric Semicontinuous Multifunction
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G-Kernel-Open Sets, G-Kernel-Neighborhoods and G-Kernel-Derived Sets 被引量:2
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作者 Li LIU 《Journal of Mathematical Research with Applications》 CSCD 2018年第3期276-286,共11页
Based on G-hulls and G-kernels under the meaning of G-methods on sets, we introduce the concepts of G-hull-closed sets, G-kernel-open sets, G-kernel-neighborhoods and G-kernel-derived sets, discuss some related proper... Based on G-hulls and G-kernels under the meaning of G-methods on sets, we introduce the concepts of G-hull-closed sets, G-kernel-open sets, G-kernel-neighborhoods and G-kernel-derived sets, discuss some related properties. In particular, we define pointwise G-methods, prove the consistency of G-closed sets and G-hull-closed sets, G-open sets and Gkernel-open sets, G-neighborhoods and G-kernel-neighborhoods, G-derived sets and G-kernelderived sets under this method, and enrich some results about G-closed sets, G-open sets,G-interiors, G-neighborhoods and G-derived sets in sets. At the same time, we put forward some problems for further research. 展开更多
关键词 topological spaces G-methods pointwise G-methods G-hull-closed sets G-kernel-open sets G-kernel-neighborhoods G-kernel-derived sets
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A Hybrid Simulation Test Platform for Verifying the Protection Settings of SPS
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作者 Jianjian Li Luojiang Qian 《Energy and Power Engineering》 2017年第4期346-351,共6页
To verify the effectiveness and correctness of the protection settings in ring structure Shipboard Power System (SPS), a digital-physical hybrid simulation platform at China Ship Development and Design Center (CSDDC) ... To verify the effectiveness and correctness of the protection settings in ring structure Shipboard Power System (SPS), a digital-physical hybrid simulation platform at China Ship Development and Design Center (CSDDC) has been built, which aims to give double verification effect of design scheme and physical device. The platform consists of eMEGAsim digital simulator, signal power amplifiers and digital-analog interface equipments. With this platform, the multiple protection device of ring structure grid can be accessed to form a close-loop test system. Since eMEGAsim model-simulated faults and actual protection device actions are on real time, the tripping settings of each device as well as their coordinate performance between multiple devices can be verified in this close-loop test. 展开更多
关键词 Hybrid Simulation SHIPBOARD Power System (SPS) PROTECTION setTINGS close-Loop TEST Verify
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基于优势关系的多粒度Pythagorean模糊粗糙集的粒度选择方法
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作者 薛占熬 杨梦丽 +2 位作者 辛现伟 郑宇 孙林 《河南师范大学学报(自然科学版)》 北大核心 2025年第3期79-87,I0008,共10页
在Pythagorean模糊粗糙集的基础上,结合优势关系与多粒度,提出了一种基于优势关系的多粒度Pythagorean模糊粗糙集模型,并对其进行研究.首先给出了优势关系的Pythagorean模糊粗糙集、Pythagorean模糊熵概念,讨论其性质,然后定义了在乐观... 在Pythagorean模糊粗糙集的基础上,结合优势关系与多粒度,提出了一种基于优势关系的多粒度Pythagorean模糊粗糙集模型,并对其进行研究.首先给出了优势关系的Pythagorean模糊粗糙集、Pythagorean模糊熵概念,讨论其性质,然后定义了在乐观、悲观下的优势关系的多粒度Pythagorean模糊粗糙集4种模型,以及Pythagorean模糊贴近度,并证明了其性质,设计了其最优粒度选择算法.通过遂昌金矿优化采矿的案例,对该模型进行了分析,验证了其有效性. 展开更多
关键词 优势关系 Pythagorean模糊集 多粒度粗糙集 模糊熵 贴近度
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串联型惯容系统多自由度结构地震响应分析
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作者 管涛 王善库 +1 位作者 葛新广 王昌盛 《计算力学学报》 北大核心 2025年第1期130-138,共9页
研究串联型惯容系统多自由度结构随机地震响应的简明封闭解,分析了惯容系统参数及设置位置对结构减震性能的影响。首先,根据串联型惯容系统力学构造图,建立多自由度结构-惯容系统耦合地震动方程。其次,运用二次式分解法推导出建筑结构... 研究串联型惯容系统多自由度结构随机地震响应的简明封闭解,分析了惯容系统参数及设置位置对结构减震性能的影响。首先,根据串联型惯容系统力学构造图,建立多自由度结构-惯容系统耦合地震动方程。其次,运用二次式分解法推导出建筑结构节点相对于地面的绝对位移、层间节点位移及串联型惯容系统阻尼力等系列响应的0~2阶谱矩的简明封闭解。最后,通过算例,验证所提方法的正确性并研究了惯容系统参数及设置位置对结构减震性能的影响。研究表明,串联型惯容系统对结构层间位移和顶层绝对位移的减震性能具有非一致性特点;在层间位移较大的楼层设置惯容系统的布置策略是经济可行的。本文可为惯容系统实际工程应用提供参考。 展开更多
关键词 串联惯容系统 简明封闭解 二次式分解法 参数分析 阻尼器布置策略
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On Drop and Weak Drop Properties for Bounded Closed Convex Sets*
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作者 张子厚 《Journal of Mathematical Research and Exposition》 CSCD 1999年第4期667-672,共6页
In this paper we prove three equivalent conditions of bounded closed convexset K in Banach space to have the drop and weak drop properties. We also give fourequivalent conditions of Banach space and its dual space to ... In this paper we prove three equivalent conditions of bounded closed convexset K in Banach space to have the drop and weak drop properties. We also give fourequivalent conditions of Banach space and its dual space to have the drop and weak dropproperties. 展开更多
关键词 Bounded closed convex set drop property weak drop property.
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REMARKS OF DIFFERENTIAL EQUATIONS ON CLOSED SUBSETS IN A BANACH SPACE
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作者 范进军 庄万 《Annals of Differential Equations》 1997年第1期53-61,共9页
We give some extensions of Monch-Harton inequalities with respect to measures of noncompactness. As an example of the application, we obtain two existencetheorems of solutions for Cauchy problems of differential equat... We give some extensions of Monch-Harton inequalities with respect to measures of noncompactness. As an example of the application, we obtain two existencetheorems of solutions for Cauchy problems of differential equations on closed setsunder weaker compactness conditions. 展开更多
关键词 differential equations in Banach spaces solutions on closed sets noncompactness measure.
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4个运动解耦的单回路两自由度三平移并联机构的拓扑设计及其位置封闭解研究 被引量:1
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作者 佘俊杰 李菊 +1 位作者 孔祥超 沈惠平 《机械传动》 北大核心 2025年第6期60-70,共11页
【目的】为了解拓扑结构相似的支链对并联机构解耦性与派生运动的影响,设计了拓扑结构相似的并联机构,分析了其拓扑特性及位置方程。【方法】首先,基于方位特征集的并联机构拓扑结构设计方法,构造了4个由相似支链组成的新型单回路空间... 【目的】为了解拓扑结构相似的支链对并联机构解耦性与派生运动的影响,设计了拓扑结构相似的并联机构,分析了其拓扑特性及位置方程。【方法】首先,基于方位特征集的并联机构拓扑结构设计方法,构造了4个由相似支链组成的新型单回路空间两自由度三平移并联机构,给出其设计过程,并计算了自由度;其次,建立这4个机构的运动学模型,导出了这些机构位置正解的一元八次方程(封闭解)并使用数值方法求得数值解;再次,通过解析法给出其符号式反解,并进行了验证;最后,分析得到了动平台独立输出运动量与派生运动量之间的内在联系。【结果】结果表明,这些单回路两自由度三平移并联机构均运动解耦且含派生运动,可用作轻量物料的三维振动筛分主机构。研究结果为机构的尺度优化、工作空间及动力学分析奠定了基础。 展开更多
关键词 方位特征集 少输入-多输出 并联机构 伴随运动 封闭解
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第三极荨麻属麻叶荨麻分支的物种界限 被引量:1
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作者 王凤英 吴增源 +4 位作者 崔涵 李垠蕾 邓莉娟 王红 刘杰 《生物多样性》 北大核心 2025年第8期48-65,共18页
基于多学科证据的整合分类学是当前解决物种界限问题的有效方法。荨麻属(Urtica)麻叶荨麻分支(cannabina Clade)广泛分布于生物多样性丰富且生态环境独特的第三极地区。然而,由于该属植物复杂的形态特征和演化历史,其近缘种之间的界限... 基于多学科证据的整合分类学是当前解决物种界限问题的有效方法。荨麻属(Urtica)麻叶荨麻分支(cannabina Clade)广泛分布于生物多样性丰富且生态环境独特的第三极地区。然而,由于该属植物复杂的形态特征和演化历史,其近缘种之间的界限仍不清楚。本研究以分布于该地区的麻叶荨麻分支(含亚种)的4个物种(麻叶荨麻Urtica cannabina、三角叶荨麻U.triangularis、异株荨麻U.dioica、高原荨麻U.hyperborea)为研究对象,选取滇藏荨麻(U.mairei)和膜叶荨麻(U.membranifolia)及近缘属为外类群,基于麻叶荨麻分支50个个体(每个种4-10个)及18个外类群样本的基因组重测序数据,提取质体基因组和“Angiosperms353核基因数据集”解析系统发育关系和群体结构,并结合地理分布以及形态性状聚类分析,开展了整合分类学研究。结果表明:(1)高原荨麻是单系类群,且在形态特征和地理分布上与其他物种分化明显,尽管与异株荨麻在喜马拉雅和横断山地区存在同域分布,但二者在海拔梯度上存在分异;(2)异株荨麻的原亚种与尾尖异株荨麻(Urtica dioica subsp.afghanica)和甘肃异株荨麻(U.dioica subsp.gansuensis)两个亚种在地理分布、形态特征及遗传组成方面均存在明显不同,暗示可能存在隐存种,其分类地位有待进一步验证;(3)三角叶荨麻、麻叶荨麻和异株荨麻等近缘物种的分布区重叠,性状和遗传聚类出现交叉,同时检测到核质冲突信号,表明种间可能存在基因渐渗。高山环境中物种的形态趋同可能是物种间性状难以区分的原因。此外,研究证实质体基因组结合“Angiosperms353核基因数据集”在近缘物种界定中有较好的应用潜力。本研究利用多重证据解析了该地区荨麻属植物的物种界限,加深了对其种间关系与分布格局的理解,并为该区域内其他类群的整合分类学研究提供了一个可借鉴的范式。 展开更多
关键词 荨麻属 近缘种 第三极 被子植物353核基因数据集 质体基因组 整合分类学 物种界限
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航空发动机高温合金大尺寸小宽径比轴端自锁螺母收口工艺分析及参数优化
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作者 陈衍祥 罗小龙 +3 位作者 李少龙 姚齐水 田坤 余江鸿 《锻压技术》 北大核心 2025年第4期172-182,共11页
为解决航空发动机用大尺寸小宽径比高温合金轴端自锁螺母收口成形中收口量不一致和齿形外翻的问题,对收口模具结构和工艺参数进行优化。以某型GH2132高温合金轴端自锁螺母为研究对象,根据生产经验初选3种收口模锥面角,通过数值仿真并基... 为解决航空发动机用大尺寸小宽径比高温合金轴端自锁螺母收口成形中收口量不一致和齿形外翻的问题,对收口模具结构和工艺参数进行优化。以某型GH2132高温合金轴端自锁螺母为研究对象,根据生产经验初选3种收口模锥面角,通过数值仿真并基于最大等效应力和收口精度确定最优锥面角。采用正交试验法和Vague集优化方法获得两组工艺参数组合,通过仿真试验对比并基于最大损伤值和最大成形载荷优选最佳参数组合,最后进行仿真试验和生产试验验证。结果表明:收口模锥面角为30°、保压时间为0.5 s、下压速度为40 mm·s^(-1)、摩擦因数为0.1条件下,可有效解决该型自锁螺母收口量不一致和齿形外翻的问题。该研究可为其他型号自锁螺母的工艺优化提供参考。 展开更多
关键词 GH2132高温合金 自锁螺母 收口成形 收口量 齿形外翻 VAGUE集
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Banach空间上拟幂零算子的幂集
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作者 胡朝龙 梁定浩 纪友清 《吉林大学学报(理学版)》 北大核心 2025年第1期15-23,共9页
令T是无穷维复Banach空间X上的拟幂零算子,且x∈X\{0}.定义k_(x)=lim sup_(λ→0)ln‖(λ-T)^(-1)x‖/ln‖(λ-T)^(-1)‖.令Λ(T)={k_(x):x≠0},称为T的幂集.证明Λ(T)是右闭的,即对Λ(T)的每个非空有界子集σ有supσ∈Λ(T).特别地,证... 令T是无穷维复Banach空间X上的拟幂零算子,且x∈X\{0}.定义k_(x)=lim sup_(λ→0)ln‖(λ-T)^(-1)x‖/ln‖(λ-T)^(-1)‖.令Λ(T)={k_(x):x≠0},称为T的幂集.证明Λ(T)是右闭的,即对Λ(T)的每个非空有界子集σ有supσ∈Λ(T).特别地,证明对任意无穷维复Banach空间X,存在X上的拟幂零算子T,使得Λ(T)=[0,1]. 展开更多
关键词 拟幂零算子 幂集 右闭性 Schauder基序列
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