期刊文献+
共找到878篇文章
< 1 2 44 >
每页显示 20 50 100
Existence of Monotone Positive Solution for a Fourth-Order Three-Point BVP with Sign-Changing Green’s Function
1
作者 Junrui Yue Yun Zhang Qingyue Bai 《Open Journal of Applied Sciences》 2024年第1期63-69,共7页
This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones a... This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique. 展开更多
关键词 Fourth-Order Three-point Boundary Value Problem sign-Changing Green’s Function Fixed point Index Iterative Technique Monotone Positive solution EXIsTENCE
下载PDF
S-T-S混合式循环互助教学模式用于少学时“化工原理”课程
2
作者 吕玲 《教育教学论坛》 2024年第31期157-160,共4页
“化工原理”课程是化工及相关专业的专业基础课程,相关专业的学时少,课程难,需重点解决的问题是“三多”“三不愿”“三不明”。针对痛点问题,提出了线上线下混合式循环互助的创新设计思路,包括:教师帮助学生自制课前、课中、课后习题... “化工原理”课程是化工及相关专业的专业基础课程,相关专业的学时少,课程难,需重点解决的问题是“三多”“三不愿”“三不明”。针对痛点问题,提出了线上线下混合式循环互助的创新设计思路,包括:教师帮助学生自制课前、课中、课后习题,学生帮助教师反馈真实学习情况,学生帮助学生组团互助学习。问卷调查和评教结果显示,在一定程度上解决了“三多”“三不愿”的问题;通过建立“助教团队”反馈不同层次学生的学习情况,较好地解决了“三不明”的问题。学生的成绩与教改前相比有明显提高。 展开更多
关键词 线上线下 s-T-s教学模式 化工原理 痛点问题
下载PDF
2023年12月18日甘肃积石山M_(S)6.2地震多点源地震矩张量反演研究 被引量:1
3
作者 刘俊清 张小刚 +3 位作者 张宇 蔡宏雷 陈卓 包秀敏 《地震》 CSCD 北大核心 2024年第2期169-177,共9页
基于区域宽频带数字地震台网观测到的地震记录,采用多点源地震矩张量反演方法对2023年甘肃积石山M_(S)6.2地震进行了地震矩张量反演研究。结果显示,该地震震源机制解的NE倾的节面(走向312°,倾角48°,滑动角76°)为发震断裂... 基于区域宽频带数字地震台网观测到的地震记录,采用多点源地震矩张量反演方法对2023年甘肃积石山M_(S)6.2地震进行了地震矩张量反演研究。结果显示,该地震震源机制解的NE倾的节面(走向312°,倾角48°,滑动角76°)为发震断裂,主体地震矩从震源向地表沿滑动矢量的方向(方位角236°,倾伏角40.5°)释放,主破裂持续时间约为5.8 s,与此同时,地震破裂区断层面上发生了次级的双侧破裂。 展开更多
关键词 积石山6.2级地震 地震矩张量 多点源 发震构造
下载PDF
On Some Novel Fixed Point Results for Generalized F-Contractions in b-Metric-Like Spaces with Application
4
作者 Kastriot Zoto Ilir Vardhami +2 位作者 Dusan Bajovic Zoran D.Mitrovic Stojan Radenovic 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第4期673-686,共14页
The focusofourwork is on themost recent results infixedpoint theoryrelated tocontractivemappings.Wedescribe variants of(s,q,φ,F)-contractions that expand,supplement and unify an important work widely discussed in the... The focusofourwork is on themost recent results infixedpoint theoryrelated tocontractivemappings.Wedescribe variants of(s,q,φ,F)-contractions that expand,supplement and unify an important work widely discussed in the literature,based on existing classes of interpolative and F-contractions.In particular,a large class of contractions in terms of s,q,φand F for both linear and nonlinear contractions are defined in the framework of b-metric-like spaces.The main result in our paper is that(s,q,φ,F)-g-weak contractions have a fixed point in b-metric-like spaces if function F or the specified contraction is continuous.As an application of our results,we have shown the existence and uniqueness of solutions of some classes of nonlinear integral equations. 展开更多
关键词 F)-contraction (s q φ F)-contraction b-metric-like space fixed point
下载PDF
Child’s Point of View vs.Adult’s in Melville’s Early Two Stories
5
作者 YANG Jiayun 《Sino-US English Teaching》 2023年第10期392-395,共4页
This paper aims to study the functions of two different points of view from the perspective of narratology,namely,the point of view of the adult and the one of the child,in two of Herman Melville’s early stories.By c... This paper aims to study the functions of two different points of view from the perspective of narratology,namely,the point of view of the adult and the one of the child,in two of Herman Melville’s early stories.By contrasting these two functions of the different perspectives,the author of this paper draws the conclusion that the child has a unique and significant perspective in Melville’s works. 展开更多
关键词 point of view child’s point of view adult’s point of view
下载PDF
A Proof of Brouwer’s Fixed Point Theorem Using Sperner’s Lemma
6
作者 Cassie Lu 《数学计算(中英文版)》 2023年第2期1-6,共6页
This article offers a simple but rigorous proof of Brouwer’s fixed point theorem using Sperner’s Lemma.The general method I have used so far in the proof is mainly to convert the n-dimensional shapes to the correspo... This article offers a simple but rigorous proof of Brouwer’s fixed point theorem using Sperner’s Lemma.The general method I have used so far in the proof is mainly to convert the n-dimensional shapes to the corresponding case under the Sperner’s Labeling and apply the Sperner’s Lemma to solve the question. 展开更多
关键词 Brouwer’s Fixed point Theorem sperner’s Lemma PROOF
下载PDF
赋s范数Orlicz函数空间的光滑点
7
作者 徐浩 王俊明 《哈尔滨理工大学学报》 CAS 北大核心 2024年第2期147-152,共6页
光滑点是巴拿赫空间几何理论中的重要概念,在估计理论,概率论等领域有重要应用。本文中,首先用凸模引入赋s-范数Orlicz空间对偶空间范数,然后讨论对偶范数的范数可达性,在此基础上给出赋s-范数Or-licz空间的支撑泛函的显式形式,最后给出... 光滑点是巴拿赫空间几何理论中的重要概念,在估计理论,概率论等领域有重要应用。本文中,首先用凸模引入赋s-范数Orlicz空间对偶空间范数,然后讨论对偶范数的范数可达性,在此基础上给出赋s-范数Or-licz空间的支撑泛函的显式形式,最后给出赋s-范数Orlicz空间光滑点的判据。 展开更多
关键词 Olicz函数空间 s-范数 支撑泛函 光滑点
下载PDF
“S”形检测试件测量结果可视化研究及其软件开发
8
作者 刘福民 高诚 冯长征 《制造技术与机床》 北大核心 2024年第8期158-168,共11页
“S”形检测试件已成为国内航空主机厂商检验五轴联动数控机床加工性能的一项必要环节,为方便机床调试人员分析数控机床误差,提高调试效率,对S形试件测量结果可视化进行研究。分析了S形试件的几何特性及现有测量方法,通过获取S形试件的... “S”形检测试件已成为国内航空主机厂商检验五轴联动数控机床加工性能的一项必要环节,为方便机床调试人员分析数控机床误差,提高调试效率,对S形试件测量结果可视化进行研究。分析了S形试件的几何特性及现有测量方法,通过获取S形试件的点云数据,对点云数据进行预处理,为S形试件测量结果的可视化奠定了基础。利用克里金插值法将试件测量点的点位误差映射到整个形面的点云上,得到了密化的形面误差数据,利用色谱图和分层显示的方式实现了S形试件测量结果的可视化显示,并对可视化结果进行了实验验证。基于上述处理流程及相关算法,基于Python语言,开发了S形试件测量结果可视化软件。此种方法开发的可视化软件小巧、轻量化且可移植性强,适合工程应用。 展开更多
关键词 s”形检测试件 可视化 点云 克里金插值法 PYTHON 工程应用
下载PDF
The Criteria for Reducing Centrally Restricted Three-Body Problem to Two-Body Problem
9
作者 Bijay Kumar Sharma 《International Journal of Astronomy and Astrophysics》 2024年第1期1-19,共19页
Our Solar System contains eight planets and their respective natural satellites excepting the inner two planets Mercury and Venus. A satellite hosted by a given Planet is well protected by the gravitational pertubatio... Our Solar System contains eight planets and their respective natural satellites excepting the inner two planets Mercury and Venus. A satellite hosted by a given Planet is well protected by the gravitational pertubation of much heavier planets such as Jupiter and Saturn if the natural satellite lies deep inside the respective host Planet Hill sphere. Each planet has a Hill radius a<sub>H</sub> and planet mean radius R<sub>P </sub>and the ratio R<sub>1</sub>=R<sub>P</sub>/a<sub>H</sub>. Under very low R<sub>1 </sub>(less than 0.006) the approximation of CRTBP (centrally restricted three-body problem) to two-body problem is valid and planet has spacious Hill lobe to capture a satellite and retain it. This ensures a high probability of capture of natural satellite by the given planet and Sun’s perturbation on Planet-Satellite binary can be neglected. This is the case with Earth, Mars, Jupiter, Saturn, Neptune and Uranus. But Mercury and Venus has R<sub>1</sub>=R<sub>P</sub>/a<sub>H</sub> =0.01 and 5.9862 × 10<sup>-3</sup> respectively hence they have no satellites. There is a limit to the dimension of the captured body. It must be a much smaller body both dimensionally as well masswise. The qantitative limit is a subject of an independent study. 展开更多
关键词 Hill’s Radius Two-Body Problem Fixed-point solution Lagrange points Earth-Moon-Test Particle CRTBP
下载PDF
具有饱和恢复率的SEIR时滞模型的行波解
10
作者 卫珍妮 《西北师范大学学报(自然科学版)》 2024年第1期20-29,共10页
研究一类具有饱和恢复率的SEIR时滞模型的行波解.首先,考虑一类二维系统初值问题的适定性;然后,通过构造一对有界的向量值上、下解得到一个闭凸集;最后,利用Schauder不动点定理证明:当基本再生数R^(0)>1,波速c>c^(*)时模型存在非... 研究一类具有饱和恢复率的SEIR时滞模型的行波解.首先,考虑一类二维系统初值问题的适定性;然后,通过构造一对有界的向量值上、下解得到一个闭凸集;最后,利用Schauder不动点定理证明:当基本再生数R^(0)>1,波速c>c^(*)时模型存在非平凡行波解. 展开更多
关键词 sEIR模型 饱和恢复率 时滞 行波解 sCHAUDER不动点定理
下载PDF
基于T-S模糊神经网络的光伏发电机组自动控制
11
作者 杨振睿 沈主浮 +2 位作者 孙辰 蔡斌 姜宽 《机械与电子》 2024年第2期35-39,共5页
光照情况变化会使光伏发电机组功率呈现不稳定性,加大光伏发电机组控制难度,为此,设计了基于T-S模糊神经网络的光伏发电机组自动控制方法。构建光伏阵列数学模型,分析在均匀和不均匀2种光照情况下光伏发电机组特性曲线。以分析结果为依... 光照情况变化会使光伏发电机组功率呈现不稳定性,加大光伏发电机组控制难度,为此,设计了基于T-S模糊神经网络的光伏发电机组自动控制方法。构建光伏阵列数学模型,分析在均匀和不均匀2种光照情况下光伏发电机组特性曲线。以分析结果为依据,采用T-S模糊神经网络构建光伏发电机组自动控制模型。为保证良好的控制效果,引入定比因子优化隶属度函数,输出最佳跟踪结果,结合最佳跟踪结果和自动控制模型实现光伏发电机组自动控制。测试结果显示,该方法能够完成光伏阵列特性分析,控制效果好。 展开更多
关键词 T-s模糊神经网络 光伏发电机组 自动控制 特性曲线 最大功率点 光照情况
下载PDF
LSFP下的机器人视觉定位技术研究
12
作者 魏永超 邓毅 +3 位作者 李涛 李锦 朱姿翰 徐未其 《激光杂志》 CAS 北大核心 2023年第4期25-31,共7页
针对当前点云的定位算法中,多平面分割效果差、误匹配以及定位精度不够高等问题,提出LSFP的定位思想和C-S分割算法,对目标物体进行定位。在深度相机场景下,利用点云处理算法初步获取目标的位姿,经手眼标定后,进行初步引导;再使用3D扫描... 针对当前点云的定位算法中,多平面分割效果差、误匹配以及定位精度不够高等问题,提出LSFP的定位思想和C-S分割算法,对目标物体进行定位。在深度相机场景下,利用点云处理算法初步获取目标的位姿,经手眼标定后,进行初步引导;再使用3D扫描仪进一步定位目标物体。结果表明:(1)C-S分割算法对多平面分割效果良好,能更准确地去除多余平面,减少点云数量。(2)在垂直于Z轴且Z轴坐标值为171 mm和-10 mm的平面上,仅PrimeSense的定位距离的均方根误差为7.3 mm和8.2 mm,LSFP下的定位距离的均方根误差为2.6 mm和3.2 mm。(3)LSFP定位思想能扩大场景定位的范围,提高物体的定位精度,具有良好的准确性。 展开更多
关键词 三维点云 位姿估计 LsFP C-s分割算法 手眼标定
下载PDF
SOME NEW EXTENSIONS OF EDELSTEIN-SUZUKI-TYPE FIXED POINT THEOREM TO G-METRIC AND G-CONE METRIC SPACES 被引量:3
13
作者 Fridoun MORADLOU Peyman SALIMI Pasquale VETRO 《Acta Mathematica Scientia》 SCIE CSCD 2013年第4期1049-1058,共10页
In this paper, we prove some fixed point theorems for generalized contractions in the setting of G-metric spaces. Our results extend a result of Edelstein [M. Edelstein, On fixed and periodic points under contractive ... In this paper, we prove some fixed point theorems for generalized contractions in the setting of G-metric spaces. Our results extend a result of Edelstein [M. Edelstein, On fixed and periodic points under contractive mappings, J. London Math. Soc., 37 (1962), 74-79] and a result of Suzuki [T. Suzuki, A new type of fixed point theorem in metric spaces, Nonlinear Anal., 71 (2009), 5313-5317]. We prove, also, a fixed point theorem in the setting of G-cone metric spaces. 展开更多
关键词 G-metric spaces G-cone metric spaces fixed point Edelstein's theorem suzuki's theorem
下载PDF
Existence of Positive Solutions for a Third-Order Multi-Point Boundary Value Problem 被引量:2
14
作者 A. Guezane-Lakoud L. Zenkoufi 《Applied Mathematics》 2012年第9期1008-1013,共6页
By using Leray-Schauder nonlinear alternative, Banach contraction theorem and Guo-Krasnosel’skii theorem, we discuss the existence, uniqueness and positivity of solution to the third-order multi-point nonhomogeneous ... By using Leray-Schauder nonlinear alternative, Banach contraction theorem and Guo-Krasnosel’skii theorem, we discuss the existence, uniqueness and positivity of solution to the third-order multi-point nonhomogeneous boundary value problem (BVP1): where for The interesting point lies in the fact that the nonlinear term is allowed to depend on the first order derivative . 展开更多
关键词 Guo’s Fixed point THEOREM Three point Boundary Value Problem Positive solution LERAY sCHAUDER Non-Linear Alternative CONTRACTION Principle
下载PDF
Existence of Positive Solutions of Three-point Boundary Value Problem for Higher Order Nonlinear Fractional Differential Equations 被引量:2
15
作者 韩仁基 葛建生 蒋威 《Chinese Quarterly Journal of Mathematics》 CSCD 2012年第4期516-525,共10页
In this paper, we consider the positive solutions of fractional three-point boundary value problem of the form Dο^α+u(t)+f(t,u(t),u'(t),…,u^(n-3)(5),u^(n-2)(t))=0,u^(i)(0)=0,0≤i≤n-2,u^(n-... In this paper, we consider the positive solutions of fractional three-point boundary value problem of the form Dο^α+u(t)+f(t,u(t),u'(t),…,u^(n-3)(5),u^(n-2)(t))=0,u^(i)(0)=0,0≤i≤n-2,u^(n-2)(1)-βu^(n-2)(ξ)=0,where 0〈t〈1,n-1〈α≤n,n≥2,ξ Е(0,1),βξ^a-n〈1. We first transform it into another equivalent boundary value problem. Then, we derive the Green's function for the equivalent boundary value problem and show that it satisfies certain properties. At last, by using some fixed-point theorems, we obtain the existence of positive solution for this problem. Example is given to illustrate the effectiveness of our result. 展开更多
关键词 nonlinear fractional differential equation three-point boundary value problem positive solutions green’s function banach contraction mapping fixed point theorem in cones
下载PDF
Common Fixed Point Theorems of Single-valued and Set-valued Mappings in Complete,Convex Metric Spaces 被引量:1
16
作者 LIANGJun-qi ZHANGZhi-hong ZHAOLing 《Chinese Quarterly Journal of Mathematics》 CSCD 2003年第3期264-270,共7页
Under the conditions of compatility or sub -c ompatility between a sigle-valued mapping and set-valued mapping, this paper d iscusses the existence of common fixed points for two set-valued mappings and a single-value... Under the conditions of compatility or sub -c ompatility between a sigle-valued mapping and set-valued mapping, this paper d iscusses the existence of common fixed points for two set-valued mappings and a single-valued mapping in complete, convex matric spaces. We extend and develop the main results. 展开更多
关键词 complete convex metric spaces compatible mappings s ub-compatible mappings common fixed point theorems
下载PDF
The ~3.6 to 3.7 M Paucity in Global Earthquake Frequency: Potential Coupling to Zero Point Fluctuation Force and Quantum Energies 被引量:1
17
作者 David A. E. Vares Michael A. Persinger 《International Journal of Geosciences》 2013年第10期1321-1325,共5页
There has been protracted historical evidence of a relative paucity in the distribution frequency of global earthquakes within the M = 3.5 to 4.0 range. We observed a similar phenomenon for all recently recorded earth... There has been protracted historical evidence of a relative paucity in the distribution frequency of global earthquakes within the M = 3.5 to 4.0 range. We observed a similar phenomenon for all recently recorded earthquakes from January 2009 through August 2013. Frequency distributions with increments of M = 0.1 verified the trough of the diminished incidence to be between M = 3.6 and 3.7 with an abrupt increase between M = 3.9 and 4.0. The calculated equivalent photon wavelength for the energies associated with M = 3.6 approaches Planck’s Length while the related time increment is the cutoff frequency for the Zero Point Fluctuation force coupled to gravity. The conspicuous congruence between Planck’s time and length and the lower than expected frequency based upon Gaussian assumptions of distribution for the discrete band of energy associated with this magnitude range of earthquakes suggests a conduit may exist between intrinsic features of Planck space-time and geophysical processes. The existence of such a connection would encourage alternative explanations for sun-seismic activities as due to solar instabilities. Instead, it may reflect influence upon both from alterations in the structure of space being traversed by the solar system as it moves through the galaxy. 展开更多
关键词 Low MAGNITUDE Earthquake Frequency GAUssIAN Distribution Planck’s Length Energy Zero point FLUCTUATION Frequencies QUANTUM GEOPHYsICAL Effects
下载PDF
Stochastic Approximation Method for Fixed Point Problems 被引量:1
18
作者 Ya. I. Alber C. E. Chidume Jinlu Li 《Applied Mathematics》 2012年第12期2123-2132,共10页
We study iterative processes of stochastic approximation for finding fixed points of weakly contractive and nonexpansive operators in Hilbert spaces under the condition that operators are given with random errors. We ... We study iterative processes of stochastic approximation for finding fixed points of weakly contractive and nonexpansive operators in Hilbert spaces under the condition that operators are given with random errors. We prove mean square convergence and convergence almost sure (a.s.) of iterative approximations and establish both asymptotic and nonasymptotic estimates of the convergence rate in degenerate and non-degenerate cases. Previously the stochastic approximation algorithms were studied mainly for optimization problems. 展开更多
关键词 HILBERT spaces sTOCHAsTIC Approximation Algorithm Weakly Contractive OPERATORs NONEXPANsIVE OPERATORs Fixed points CONVERGENCE in Mean square CONVERGENCE ALMOsT sure (a.s.) Nonasymptotic Estimates of CONVERGENCE Rate
下载PDF
SET-VALUED CARISTI’S FIXED POINT THEOREM AND EEELAND’S VARIATIONAL PRINCIPLE
19
作者 张石生 罗群 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1989年第2期119-121,共3页
This paper proposes a formally stronger set-valued Caristi’s fixed point theorem and by using a simple method we give a direct proof for the equivalence between Ekeland’s variational principle and this set-valued Ca... This paper proposes a formally stronger set-valued Caristi’s fixed point theorem and by using a simple method we give a direct proof for the equivalence between Ekeland’s variational principle and this set-valued Caristi’s fixed point theorem.The results stated in this paper improve and strengthen the corresponding results in[4]. 展开更多
关键词 s FIXED point THEOREM AND EEELAND s VARIATIONAL PRINCIPLE sET-VALUED CARIsTI
下载PDF
Spectrum behavior for the nonlinear fractional point reactor kinetics model
20
作者 Ahmed E.Aboanber Abdallah A.Nahla A.A.Hemeda 《Nuclear Science and Techniques》 SCIE CAS CSCD 2018年第1期96-109,共14页
The nonlinear fractional point reactor kinetics equation in the presence of Newtonian temperature reactivity feedback with a multi-group of delayed neutrons,which describes the spectrum behavior of neutron density int... The nonlinear fractional point reactor kinetics equation in the presence of Newtonian temperature reactivity feedback with a multi-group of delayed neutrons,which describes the spectrum behavior of neutron density into the homogenous nuclear reactors, is developed. This system is one of the most important stiff coupled nonlinear fractional differentials for nuclear reactor dynamics. The generalization of Taylor's formula that involves Caputo fractional derivatives is developed in an attempt to overcome the difficulty of the stiffness of the nonlinear fractional differential model. Moreover, the general fractional derivatives are calculated analytically throughout this work. Furthermore, the local and global estimated errors were analyzed, which suggest that the error quantification should take into account the possible grow in time of the error. This observation provides a motivation for going beyond more classical local-in-time concepts of error(local truncation error). The neutron density response with time is analyzed for the anomalous diffusion, sub-diffusion, and super-diffusion processes. 展开更多
关键词 Nonlinear FRACTIONAL Generalized Taylor’s FORMULA point kinetics MULTI-GROUP DELAYED neutrons Temperature feedback REACTIVITY
下载PDF
上一页 1 2 44 下一页 到第
使用帮助 返回顶部