期刊文献+
共找到319篇文章
< 1 2 16 >
每页显示 20 50 100
ON AMODIFIED NEWTON'S METHOD AND CONVERGENCE
1
作者 韩丹夫 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 1997年第1期107-112,共6页
In this paper we discuss the convergence of a modified Newton’s method presented by A. Ostrowski [1] and J.F. Traub [2], which has quadratic convergence order but reduces one evaluation of the derivative at every two... In this paper we discuss the convergence of a modified Newton’s method presented by A. Ostrowski [1] and J.F. Traub [2], which has quadratic convergence order but reduces one evaluation of the derivative at every two steps compared with Newton’s method. A convergence theorem is established by using a weak condition a≤3-2(2<sup>1/2</sup>) and a sharp error estimate is given about the iterative sequence. 展开更多
关键词 modified Newton’s method CONVErGENCE majurant method ErrOr estimate.
在线阅读 下载PDF
Symmetry and Exact Solutions of (2+1)-Dimensional Generalized Sasa-Satsuma Equation via a Modified Direct Method
2
作者 LU Chang-Cheng CHEN Yong 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第6期973-978,共6页
In this paper, first, we employ classic Lie symmetry groups approach to obtain the Lie symmetry groupsof the well-known (2+1)-dimensional Generalized Sasa-Satsuma (GSS) equation. Second, based on a modified directmeth... In this paper, first, we employ classic Lie symmetry groups approach to obtain the Lie symmetry groupsof the well-known (2+1)-dimensional Generalized Sasa-Satsuma (GSS) equation. Second, based on a modified directmethod proposed by Lou [J. Phys. A: Math. Gen. 38 (2005) L129], more general symmetry groups are obtained andthe relationship between the new solution and known solution is set up. At the same time, the Lie symmetry groupsobtained are only special cases of the more general symmetry groups. At last, some exact solutions of GSS equationsare constructed by the relationship obtained in the paper between the new solution and known solution. 展开更多
关键词 classic Lie symmetry groups approach modified CK's direct method generalized sasa-satsuma equation
在线阅读 下载PDF
Modified Kadomtsev-Petviashvili Equation in (3+1) Dimensions:Multiple Front-Wave Solutions
3
作者 A.M.Wazwaz XU Gui-Qiong 《Communications in Theoretical Physics》 SCIE CAS CSCD 2015年第6期727-730,共4页
A modified Kadomtsev-Petviashvili (mKP) equation in (3+1) dimensions is presented. We reveal multiple front-waves solutions for this higher-dimensional developed equation, and multiple singular front-wave solutio... A modified Kadomtsev-Petviashvili (mKP) equation in (3+1) dimensions is presented. We reveal multiple front-waves solutions for this higher-dimensional developed equation, and multiple singular front-wave solutions as well. The constraints on the coefficients of the spatial variables, that assure the existence of these multiple front-wave solutions are investigated. We also show that this equation falls the Painleve test, and we conclude that it is not integrable in the sense of possessing the Painleve property, although it gives multiple front-wave solutions. 展开更多
关键词 modified Kadomtsev-Petviashvili equation multiple front-waves solutions Hirota's method
原文传递
Fractal Method for Statistical Analysis Geological Data 被引量:2
4
作者 Meng Xianguo Zhao PengdaChina University of Geosciences , Wuhan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1991年第1期114-119,共6页
This paper establishes the phase space in the light of spacial series data , discusses the fractal structure of geological data in terms of correlated functions and studies the chaos of these data . In addition , it i... This paper establishes the phase space in the light of spacial series data , discusses the fractal structure of geological data in terms of correlated functions and studies the chaos of these data . In addition , it introduces the R/S analysis for time series analysis into spacial series to calculate the structural fractal dimensions of ranges and standard deviation for spacial series data -and to establish the fractal dimension matrix and the procedures in plotting the fractal dimension anomaly diagram with vector distances of fractal dimension . At last , it has examples of its application . 展开更多
关键词 geological data fractal method fractal dimension space series r/s analysis .
在线阅读 下载PDF
Research on nonlinear R/S method and its application in earthquake prediction 被引量:1
5
作者 王碧泉 黄汉明 +2 位作者 范洪顺 王春珍 陈佩燕 《Acta Seismologica Sinica(English Edition)》 CSCD 1995年第4期653-658,共6页
ResearchonnonlinearR/SmethodanditspplicationinearthquakepredictionBi-QuanWANG(王碧泉);Han-MingHUANG(黄汉明);Hong-S... ResearchonnonlinearR/SmethodanditspplicationinearthquakepredictionBi-QuanWANG(王碧泉);Han-MingHUANG(黄汉明);Hong-ShunFAN(范洪顺);Chuen... 展开更多
关键词 nonlinear theory fractal dimension earthquake prediction r/s method
在线阅读 下载PDF
Nonlinear constrained optimization using the flexible tolerance method hybridized with different unconstrained methods 被引量:1
6
作者 Alice Medeiros Lima Antonio Jose Goncalves Cruz Wu Hong Kwong 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第4期442-452,共11页
This paper proposes the use of the flexible tolerance method(FTM) modified with scaling of variables and hybridized with different unconstrained optimization methods to solve real constrained optimization problems.The... This paper proposes the use of the flexible tolerance method(FTM) modified with scaling of variables and hybridized with different unconstrained optimization methods to solve real constrained optimization problems.The benchmark problems used to analyze the performance of the methods were taken from G-Suite functions.The original method(FTM) and other four proposed methods:(i) FTM with scaling of variables(FTMS),(ii) FTMS hybridized with BFGS(FTMS-BFGS),(iii) FTMS hybridized with modified Powell's method(FTMS-Powell)and(iv) FTMS hybridized with PSO(FTMS-PSO), were implemented. The success rates of the methods were 80%,100%, 75%, 95% and 85%, for FTM, FTMS, FTMS-BFGS, FTMS-Powell and FTMS-PSO, respectively. Numerical experiments including real constrained problems indicated that FTMS gave the best performance, followed by FTMSPowell and FTMS-PSO. Despite the inferior performance compared to FTMS and FTMS-Powell, the FTMS-PSO method presented some advantages since good different initial points could be obtained, which allow exploring different routes through the solution space and to escape from local optima. The proposed methods proved to be an effective way of improving the performance of the original FTM. 展开更多
关键词 Flexible tolerance method modified Powell’s method BFGs PsO scaling HYBrIDIZATION
在线阅读 下载PDF
Application of the Improved Kudryashov Method to Solve the Fractional Nonlinear Partial Differential Equations 被引量:3
7
作者 Md. Abdus Salam Umme Habiba 《Journal of Applied Mathematics and Physics》 2019年第4期912-920,共9页
Our purpose of this paper is to apply the improved Kudryashov method for solving various types of nonlinear fractional partial differential equations. As an application, the time-space fractional Korteweg-de Vries-Bur... Our purpose of this paper is to apply the improved Kudryashov method for solving various types of nonlinear fractional partial differential equations. As an application, the time-space fractional Korteweg-de Vries-Burger (KdV-Burger) equation is solved using this method and we get some new travelling wave solutions. To acquire our purpose a complex transformation has been also used to reduce nonlinear fractional partial differential equations to nonlinear ordinary differential equations of integer order, in the sense of the Jumarie’s modified Riemann-Liouville derivative. Afterwards, the improved Kudryashov method is implemented and we get our required reliable solutions where the results are justified by mathematical software Maple-13. 展开更多
关键词 IMPrOVED Kudryashov method Time-space FrACTIONAL KdV-Burger Equation TrAVELLING Wave solutions Jumarie’s modified riemann-Liouville Derivative
在线阅读 下载PDF
R/S method for evaluation of pollutant time series in environmental quality assessment
8
作者 Bu Quanmin Bi Jun +1 位作者 Yuan Zengwei Huang Lei 《Water Science and Engineering》 EI CAS 2008年第4期82-88,共7页
The significance of the fluctuation and randomness of the time series of each pollutant in environmental quality assessment is described for the first time in this paper. A comparative study was made of three differen... The significance of the fluctuation and randomness of the time series of each pollutant in environmental quality assessment is described for the first time in this paper. A comparative study was made of three different computing methods: the same starting point method, the striding averaging method, and the stagger phase averaging method. All of them can be used to calculate the Hurst index, which quantifies fluctuation and randomness. This study used real water quality data from Shazhu monitoring station on Taihu Lake in Wuxi, Jiangsu Province. The results show that, of the three methods, the stagger phase averaging method is best for calculating the Hurst index of a pollutant time series from the perspective of statistical regularity. 展开更多
关键词 environmental quality assessment time series fractal dimension r/s statistical method Hurst index
在线阅读 下载PDF
Estimating GARCH Modeling Using Metropolis-Hastings Method in R
9
作者 Min Wang Yunshun Wu 《Open Journal of Statistics》 2018年第6期931-938,共8页
This paper mainly talks about a popular approach of volatility of a GARCH-type model in R, while the disturbances are independent and have identical Student-t distribution. It uses the Metropolis-Hastings method to pe... This paper mainly talks about a popular approach of volatility of a GARCH-type model in R, while the disturbances are independent and have identical Student-t distribution. It uses the Metropolis-Hastings method to perform the computations and gives the programs in details in R. 展开更多
关键词 student’s t Distribution DEGrEE of FrEEDOM GArCH t Model r METrOPOLIs-HAsTINGs method
在线阅读 下载PDF
Stability Control of Stretch-Twist-Fold Flow by Using Numerical Methods
10
作者 Shahab Ud-Din Khan Yonglu Shu Salah Ud-Din Khan 《World Journal of Mechanics》 2012年第6期334-338,共5页
In this study, the multistep method is applied to the STF system. This method has been tested on the STF system, which is a three-dimensional system of ODE with quadratic nonlinearities. A computer based Matlab progra... In this study, the multistep method is applied to the STF system. This method has been tested on the STF system, which is a three-dimensional system of ODE with quadratic nonlinearities. A computer based Matlab program has been developed in order to solve the STF system. Stable and unstable position of the system has been analyzed graphically and finally a comparison as well as accuracy between two-step sizes with detail. Newton’s method has been applied to show the best convergence of this system. 展开更多
关键词 sTF system CHAOs modified method Fixed Point ITErATION method Newton’s method
在线阅读 下载PDF
Studies on the Synthesis, Growth and Characterization of ([Paranitrophenyl]Imino)Benzene NLO Crystal by Sankaranarayanan-Ramasamy Method
11
作者 S. Anbarasu T. Kishore Kumar Prem Anand Devarajan 《Journal of Minerals and Materials Characterization and Engineering》 2013年第3期110-116,共7页
The study of imine-bridged organics has been the hot spot synthesis of second order nonlinear optical (SONLO) and photo-responsive materials in recent years. Herein we present a study of synthesis, growth, and charact... The study of imine-bridged organics has been the hot spot synthesis of second order nonlinear optical (SONLO) and photo-responsive materials in recent years. Herein we present a study of synthesis, growth, and characterization of ([paranitrophenyl]imino)benzene (PNPIB) NLO single crystal. The title compound was synthesized in one step by Schiff base formation. PNPIB single crystal of diameter of 40 mmand length 50 mmwas successfully grown by SR method using a seed as the nucleus. The growth rate formula is derived for the SR method. PNPIB single crystals of 10 mmdiameter and 60 mmheight have been grown at an average growth rate of 3 mmper day from the point seed in a glass crystallizer. Almost 100% stable crystal conversion efficiency was achieved. The as grown PNPIB crystals were characterized using single crystal X-ray diffraction (XRD), X-ray powder diffraction (XRPD), Fourier Transform Infrared (FTIR), Ultraviolet-Visible-Near Infrared (UV-Vis-NIR), 1H & 13C NMR spectral studies, dielectric measurement and NLO studies. Single crystal XRD analysis confirms that the grown ingot belongs to the space group of P2 of monoclinic system thus exhibiting noncentrosymmetric structure. The crystalline perfection was assessed by XRPD. The powder diffraction pattern of the grown crystal has been indexed. The presence of C=N bond with intramolecular hydrogen bonding and the protonation of ions were confirmed by FTIR analysis. The UV-Vis-NIR spectrum of the crystal shows that the crystal has a cut-off at 298 nm. The 1H & 13C NMR spectra confirm the molecular structure. The dielectric behaviour was measured in the frequency range 1 KHz - 10 KHz for the temperature range from 30℃ to 170℃. The slight decrease in dielectric constant has been observed as the frequency is increased and the dielectric loss is very low for the entire frequency range. The second harmonic generation (SHG) in the crystal was observed by Kurtz powder technique. 展开更多
关键词 single CrYsTAL GrOWTH s-r method Nonlinear Optical Materials
在线阅读 下载PDF
R/S分析法在地下水动态分析中的应用 被引量:64
12
作者 黄勇 周志芳 +1 位作者 王锦国 王军辉 《河海大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第1期83-87,共5页
对R/S分析法中的Hurst经验公式进行了修正 ,并采用修正后的Hurst经验公式分析了地下水动态过程 .实例表明 ,采用R/S分析法对地下水动态过程进行分析是合理的 ,修正后的Hurst经验公式可以更加广泛地应用于时间序列的分析 .同时采用R/S分... 对R/S分析法中的Hurst经验公式进行了修正 ,并采用修正后的Hurst经验公式分析了地下水动态过程 .实例表明 ,采用R/S分析法对地下水动态过程进行分析是合理的 ,修正后的Hurst经验公式可以更加广泛地应用于时间序列的分析 .同时采用R/S分析法定量描述了地下水动态过程的分形特征 ,得到了其分维数 . 展开更多
关键词 地下水动态 r/s分析 时间序列 分形
在线阅读 下载PDF
基于M-K检验法与R/S法的宜宾市降水量分析 被引量:24
13
作者 甄英 杨珊 +1 位作者 何静 许斌 《四川师范大学学报(自然科学版)》 CAS 北大核心 2017年第3期392-397,共6页
依据宜宾市1963—2012年的年均降水量数据,运用Mann-Kendall法、R/S法对宜宾市的年均降水量变化趋势及特征进行分析.结果表明:宜宾市近50年年均降水量总体呈波状下降趋势,并以56.36 mm/10 a的速率递减.进一步对宜宾市的年均降水量进行Ma... 依据宜宾市1963—2012年的年均降水量数据,运用Mann-Kendall法、R/S法对宜宾市的年均降水量变化趋势及特征进行分析.结果表明:宜宾市近50年年均降水量总体呈波状下降趋势,并以56.36 mm/10 a的速率递减.进一步对宜宾市的年均降水量进行Mann-Kendall突变分析,得出突变年份为1990年,R/S法分析发现宜宾市近50年年均降水量的Hurst指数为0.698 7,具有持续性特征,由此表明在将来一段时间内,其年均降水量仍具有持续下降趋势.同时诊断发现该序列存在变异点,变异年份在1982年. 展开更多
关键词 M-K检验法 r/s 降水量 宜宾
在线阅读 下载PDF
R/S法的径流时序复杂特性研究 被引量:67
14
作者 燕爱玲 黄强 +1 位作者 刘招 王义民 《应用科学学报》 CAS CSCD 北大核心 2007年第2期214-217,共4页
R/S(重标极差)分析法是一种描述分形结构的有效方法.针对径流序列所具有的复杂的随机性和波动性,应用R/S分析法,通过对时变指数Hurst的计算及其检验,以新的视角对河川径流时间序列的分布特征、统计循环长度等复杂特性进行了有益探索.实... R/S(重标极差)分析法是一种描述分形结构的有效方法.针对径流序列所具有的复杂的随机性和波动性,应用R/S分析法,通过对时变指数Hurst的计算及其检验,以新的视角对河川径流时间序列的分布特征、统计循环长度等复杂特性进行了有益探索.实际径流时间序列的计算结果表明:黄河上游径流序列服从分形分布,具有较强的状态持续性,而且拥有一定的非周期循环,这为水资源的合理开发利用提供了一种新思路和新方法. 展开更多
关键词 径流序列 r/s分析法 HUrsT指数 分形特性
在线阅读 下载PDF
中国股市长记忆的修正R/S分析 被引量:21
15
作者 胡彦梅 张卫国 陈建忠 《数理统计与管理》 CSSCI 北大核心 2006年第1期73-77,共5页
本文在比较各种长记忆检验方法优缺点的基础上,采用修正的R/S分析检验我国沪深两股市日收益和日绝对收益序列的长记忆性。结果表明在0.05的显著水平下,两股市的日收益序列均无长记忆,但深圳成指日收益序列的记忆长度比上证综指日收益序... 本文在比较各种长记忆检验方法优缺点的基础上,采用修正的R/S分析检验我国沪深两股市日收益和日绝对收益序列的长记忆性。结果表明在0.05的显著水平下,两股市的日收益序列均无长记忆,但深圳成指日收益序列的记忆长度比上证综指日收益序列的记忆长度长;以日绝对收益序列为代表的波动序列具有较强的长记忆性。 展开更多
关键词 长记忆 修正r/s分析 HUrsT指数
在线阅读 下载PDF
R/S分析在滑坡变形趋势预测中的应用 被引量:43
16
作者 李远耀 殷坤龙 程温鸣 《岩土工程学报》 EI CAS CSCD 北大核心 2010年第8期1291-1296,共6页
R/S分析(重标度极差分析)是一种描述和刻画非线性时间序列的有效方法。针对滑坡地表位移监测时序确定性与随机性共存的复杂非线性特征,对三峡库区的一个实例滑坡的长时期位移时序进行了R/S分析。分别计算了滑坡累积位移时序和增量位移... R/S分析(重标度极差分析)是一种描述和刻画非线性时间序列的有效方法。针对滑坡地表位移监测时序确定性与随机性共存的复杂非线性特征,对三峡库区的一个实例滑坡的长时期位移时序进行了R/S分析。分别计算了滑坡累积位移时序和增量位移时序的Hurst指数,指出增量位移时序是更有效的分形结构,其Hurst指数能定量刻画滑坡的变形趋势;分析了滑坡增量位移时序的非周期循环长度,发现滑坡前缘与中后部的增量位移时序Hurst指数和非周期循环长度存在显著差别,并从滑坡变形诱发机制上解释了这一差异产生的内在原因;最后基于滑坡变形演化的力学机理,提出了一个利用增量位移时序Hurst指数判断滑坡加速变形阶段的概念模型:为提高和完善滑坡失稳时间预测预报理论,提供了一个有意义的新思路和新方法。 展开更多
关键词 滑坡 位移时间序列 r/s分析 HUrsT指数 预测预报模型
原文传递
应用R/S方法分析NDVI时间序列 被引量:14
17
作者 王新明 王长耀 牛铮 《地理与地理信息科学》 CSSCI CSCD 北大核心 2005年第5期20-23,48,共5页
针对1982—2001年月合成PAL NDVI时间序列,应用R/S方法计算中国陆地范围内的赫斯特指数。结果表明:全国范围内的赫斯特指数普遍大于0.5,意味着NDVI时间序列不是马尔科夫序列,而是存在明显的趋势性;中国陆地范围内的赫斯特指数分布存在... 针对1982—2001年月合成PAL NDVI时间序列,应用R/S方法计算中国陆地范围内的赫斯特指数。结果表明:全国范围内的赫斯特指数普遍大于0.5,意味着NDVI时间序列不是马尔科夫序列,而是存在明显的趋势性;中国陆地范围内的赫斯特指数分布存在“西高东低”的特点,说明西部NDVI时间序列表现出更强的持久性;通过分析赫斯特指数分布与陆地覆盖类型的关系发现,在同一生态地区内,裸地的赫斯特指数最高,与其它覆盖类型差异明显。陆地覆盖类型之外的自然条件和人为因素对赫斯特指数空间分布的影响有待进一步研究。 展开更多
关键词 遥感 NDVI 时间序列 r/s方法
在线阅读 下载PDF
国际汇率分形特征的实证研究:修正的R/S分析 被引量:8
18
作者 宋耀 田华 《河北大学学报(哲学社会科学版)》 CSSCI 2004年第4期93-96,共4页
首先对修正的R/S方法进行了介绍;然后通过实证研究指出国际汇率变化不服从正态分布并且汇率波动的相关性不显著;最后运用修正的R/S方法实证研究了国际汇率波动的分形特征,与使用传统R/S方法所得结论不同,通过实证说明外汇波动并不存在... 首先对修正的R/S方法进行了介绍;然后通过实证研究指出国际汇率变化不服从正态分布并且汇率波动的相关性不显著;最后运用修正的R/S方法实证研究了国际汇率波动的分形特征,与使用传统R/S方法所得结论不同,通过实证说明外汇波动并不存在明显的长程相关性。 展开更多
关键词 汇率 分形 长程相关 修正r/s分析
在线阅读 下载PDF
基于Mann-Kendall和R/S法的水文序列变化趋势分析——以苏州市为例 被引量:16
19
作者 杨金艳 赵超 +1 位作者 刘光生 徐勇 《水利水电技术》 CSCD 北大核心 2017年第2期27-30,137,共5页
由于Mann-Kendall法和R/S法均无法独立获取水文序列过去及未来的变化趋势,本文尝试将其相结合。针对苏州市水文历史数据,利用Mann-Kendall法分析水文序列过去的变化趋势、R/S法获取其分形特征,预测苏州市水资源未来趋势特征,并利用弹性... 由于Mann-Kendall法和R/S法均无法独立获取水文序列过去及未来的变化趋势,本文尝试将其相结合。针对苏州市水文历史数据,利用Mann-Kendall法分析水文序列过去的变化趋势、R/S法获取其分形特征,预测苏州市水资源未来趋势特征,并利用弹性系数法定量评估气候变化和人类活动对水资源变化的影响贡献率。结果表明:苏州市水资源量在过去的60年以及未来均呈现上升趋势,且在1979年发生突变;苏州市气候变化是径流变化的主要驱动因子,贡献率达到87%,人类活动的贡献率为13%。掌握苏州市水资源变化趋势可为苏州市水资源合理开发利用和海绵城市建设提供决策依据。 展开更多
关键词 水资源变化 r/s MANN-KENDALL法 弹性系数法 水文预测 开发利用 海绵城市 江苏省苏州市
在线阅读 下载PDF
应用重标度极差分析法(R/S)分析无定河流域水沙变化 被引量:26
20
作者 张鑫 蔡焕杰 尹晓楠 《农业工程学报》 EI CAS CSCD 北大核心 2010年第S2期212-217,共6页
河流水沙变化是降水、蒸发及下垫面条件改变的客观反映,揭示流域水沙演变规律及成因,可为水资源合理利用提供决策依据。应用R/S分析法对时变指数Hurst的计算及其检验,分析无定河流域赵石窑站和白家川站径流与输沙量时间序列的长程相关... 河流水沙变化是降水、蒸发及下垫面条件改变的客观反映,揭示流域水沙演变规律及成因,可为水资源合理利用提供决策依据。应用R/S分析法对时变指数Hurst的计算及其检验,分析无定河流域赵石窑站和白家川站径流与输沙量时间序列的长程相关性。结果表明:两站的径流时间序列的Hurst指数分别为0.56、0.61,均大于0.5,呈现长程正相关;而两站的输沙量时间序列的变化存在差异,赵石窑站的输沙量时间序列有2个突变点,分别发生在1966和1979年,3个标度分布范围的Hurst指数分别为0.97、0.71和0.90,均明显大于0.5,具有分形特性,白家川站的输沙量时间序列有3个突变点,分别发生在1966、1972和1979年,4个标度分布范围的Hurst指数分别为0.59、0.41、0.99和0.81,前2个标度范围的Hurst指数在0.5左右,服从布朗运动,后2个标度范围的Hurst指数均接近1.0,具有分形特性。因此,两站下一时段的径流与输沙量时间序列与过去时段变化趋势相同,具有继续下降的趋势。人类活动是引起这种变化的主要原因。 展开更多
关键词 水资源 径流 泥沙 径流序列 输沙量序列 r/s分析法 HUrsT指数 分形特性
在线阅读 下载PDF
上一页 1 2 16 下一页 到第
使用帮助 返回顶部