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arXiv physics/0103018physics.data-ancond-mat.stat-mechphysics.bio-ph
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趋势对去趋势波动分析的影响

Effect of Trends on Detrended Fluctuation Analysis

Kun Hu, Plamen Ch. Ivanov, Zhi Chen, Pedro Carpena, H. Eugene Stanley

摘要:

去趋势波动分析(DFA)是一种尺度分析方法,用于估计噪声信号中的长程幂律相关指数。实际系统中的许多噪声信号显示趋势,使得从DFA方法获得的缩放结果变得难以分析。我们系统地研究了三种类型的趋势-线性,周期性和幂律趋势的影响,并提供了这些趋势可能发生在真实数据中的例子。我们比较了人工生成的相关噪声和具有趋势的相关噪声的缩放结果之间的差异,并研究趋势如何导致缩放行为中出现交叉。我们发现,交叉的结果之间的竞争缩放的噪声和“明显”缩放的趋势。我们研究了这些交叉的特性如何取决于(i)线性趋势的斜率;(ii)周期趋势的振幅和周期;(iii)幂律趋势的振幅和功率;(iv)噪声的长度以及相关性。令人惊讶的是,我们发现,在有趋势的噪声信号的缩放中的交叉也遵循缩放律-即交叉的位置对趋势的参数的长程幂律依赖性。我们表明,DFA结果的噪声与趋势,可以准确地确定由叠加的DFA的单独结果的噪声和趋势,假设噪声和趋势不相关。如果不遵循该叠加规则,则表明噪声和叠加趋势不是独立的,因此去除趋势可能导致噪声的相关特性发生变化。

英文摘要:

Detrended fluctuation analysis (DFA) is a scaling analysis method used to estimate long-range power-law correlation exponents in noisy signals. Many noisy signals in real systems display trends, so that the scaling results obtained from the DFA method become difficult to analyze. We systematically study the effects of three types of trends -- linear, periodic, and power-law trends, and offer examples where these trends are likely to occur in real data. We compare the difference between the scaling results for artificially generated correlated noise and correlated noise with a trend, and study how trends lead to the appearance of crossovers in the scaling behavior. We find that crossovers result from the competition between the scaling of the noise and the ``apparent'' scaling of the trend. We study how the characteristics of these crossovers depend on (i) the slope of the linear trend; (ii) the amplitude and period of the periodic trend; (iii) the amplitude and power of the power-law trend and (iv) the length as well as the correlation properties of the noise. Surprisingly, we find that the crossovers in the scaling of noisy signals with trends also follow scaling laws -- i.e. long-range power-law dependence of the position of the crossover on the parameters of the trends. We show that the DFA result of noise with a trend can be exactly determined by the superposition of the separate results of the DFA on the noise and on the trend, assuming that the noise and the trend are not correlated. If this superposition rule is not followed, this is an indication that the noise and the superimposed trend are not independent, so that removing the trend could lead to changes in the correlation properties of the noise.

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