共查询到19条相似文献,搜索用时 156 毫秒
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易亮 《中小企业管理与科技》2012,(3)
本文运用Haar小波求解Fredholm-Volterra方程,建立了Haar小波的算子矩阵,利用Haar小波方法求解积分方程的基本思想是将求解积分方程的问题转化为求解一组代数方程组的问题。由于积分方程多出现在物理、工程等诸多应用性研究领域,且解析解难以求出,因此研究其数值解具有重要意义。 相似文献
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通常绝大多数物理问题中所涉及的实际积分是难以直接给出显式解析解的,这样的情形在电磁场的求解问题中是大量存在的.探讨勒让德方程的积分推导的应用方法,推导出与之相对应的勒让德积分公式,然后推导到球函数的积分方程,最后在电磁场的求解中加以应用. 相似文献
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一阶积分-微分方程是我们求解积分微分方程时常见的一类方程,其求解方法比较简单;而在实际问题中我们常常会遇到高阶积分-微分方程的求解,求其数值解相对比较困难。作者利用有理Haar小波的积分法和积分算子矩阵对一般的n阶Fredholm积分-微分方程进行了求解。最后给出的数值算例表明了该方法的有效性。 相似文献
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对于一阶线性方程通常,其解法主要是通过函数变化法和积分因子法求解。如通过变量变换化为变量分离方程,通过求积分因子化为恰当方程等。现对一类一阶线性微分方程的解法进行研究探索,在多种解法的基础上,提出相关理论的猜想,以及更大围绕解决相关问题。 相似文献
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本文通过对泊松方程和波动方程有关知识的简单介绍,利用二维及三维波动方程的求解的过程,详尽地介绍并证明了泊松积分在波动方程中的应用。在介绍应用时,我们主要采用了一些比较典型的例题,理论联系实际地探讨泊松积分在波动方程中的应用。 相似文献
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利用体积分方程实现了起伏地形三维电场的正演模拟。首先推导了起伏地形条件下的积分方程,在求解电并矢格林函数积分这一关键问题时,将其分解为一次电流项、一次电荷项和二次项;随后进行了模型试算,结果表明电场在地形和地下不均匀体处均有异常出现。 相似文献
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积分递推式是探究积分求解问题中不可避免的问题.积分递推式是积分求解问题中的一把钥匙,对研究各类积分有着至关重要的作用.本文整理并归纳高等数学中常见递推式,用分部积分法,拆项法等基本解法导出积分的递推式.为了使读者更加容易读懂本篇文章,本文就积分递推式的应用加以说明,列举经典而实际的例题,使学生加深对递推公式和解题方法的认识,开发学生解题能力和技巧,在学习和推论中体会高等数学的乐趣. 相似文献
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本文根据微分方程复合类型积分因子的定义,得到了复合类型积分因子存在的充要条件和计算公式,为解决某些非全微分方程求解问题提供了更加快捷的工具,避免了传统求解方法的繁琐及盲目。 相似文献
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运行电缆网时域反射信号检测与预处理技术研究。应用小波分析变换电缆网时域反射信号的奇异点进行检测与预处理误差较大,采用小波分析的反射波消噪技术提出一种小波分析最优分解层数的自适应确定函数算法。 相似文献
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K. Tribouley 《Statistica Neerlandica》1995,49(1):41-62
This paper describes a practical method for estimating multivariate densities using wavelets. As in kernel methods, wavelet methods depend on two types of parameters. On the one hand we have a functional parameter: the wavelet Ø (comparable to the kernel K ) and on the other hand we have a smoothing parameter: the resolution index (comparable to the bandwidth h ). Classically, we determine the resolution index with a cross-validation method. The advantage of wavelet methods compared to kernel methods is that we have a technique for choosing the wavelet Ø among a fixed family. Moreover, the wavelets method simplifies significantly both the theoretical and the practical computations. 相似文献
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A body of work using the continuous wavelet transform has been growing. We provide a self‐contained summary on its most relevant theoretical results, describe how such transforms can be implemented in practice, and generalize the concept of simple coherency to partial wavelet coherency and multiple wavelet coherency, moving beyond bivariate analysis. We also describe a family of wavelets, which emerges as an alternative to the popular Morlet wavelet, the generalized Morse wavelets. A user‐friendly toolbox, with examples, is attached to this paper. 相似文献
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本文建立了实际工程应用中信号的仿真模型和干扰模型,运用小波变换和数学形态学相融合的方法进行降噪,并将该方法与小波阈值方法、小波模极大值法、数学形态学方法的仿真结果进行对比分析,仿真分析结果发现小波-形态融合方法能够有效的消除噪声且能较好地保留原信号的形态特征。 相似文献
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Patrick M. Crowley 《Journal of economic surveys》2007,21(2):207-267
Abstract Wavelet analysis, although used extensively in disciplines such as signal processing, engineering, medical sciences, physics and astronomy, has not fully entered the economics discipline yet. In this survey article, wavelet analysis is introduced in an intuitive manner, and the existing economics and finance literature that utilizes wavelets is surveyed and explored. Extensive examples of exploratory wavelet analysis are given, most using Canadian, US and Finnish industrial production data. Finally, potential and possible future applications for wavelet analysis in economics are discussed. 相似文献
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In this paper, we propose two estimators, an integral estimator and a discretized estimator, for the wavelet coefficient of regression functions in nonparametric regression models with heteroscedastic variance. These estimators can be used to test the jumps of the regression function. The model allows for lagged-dependent variables and other mixing regressors. The asymptotic distributions of the statistics are established, and the asymptotic critical values are analytically obtained from the asymptotic distribution. We also use the test to determine consistent estimators for the locations of change points. The jump sizes and locations of change points can be consistently estimated using wavelet coefficients, and the convergency rates of these estimators are derived. We perform some Monte Carlo simulations to check the powers and sizes of the test statistics. Finally, we give practical examples in finance and economics to detect changes in stock returns and short-term interest rates using the empirical wavelet method. 相似文献