平稳

Then, both the stationary and non-stationary random response of hysteretic system with cubic rigidity and sticky damp were deduced and calculated. In the research of colored white noise, the filter for shaping the power spectral density was designed and the random state response of enlarged vector was gotten. With this, the experimental power spectral curve was changed into colored white noise and the random response could be easily calculated.

对平稳白噪声，给出了平稳响应的求解方法并对平稳状态下的模型参数对响应的影响进行了比较与分析；在有色白噪声的研究里，通过有色白噪声的扩阶方法和构造成型滤波器来计算有色白噪声的响应，从而解决一类工程实际振动问题的仿真模拟。

Objective To study the power spectrum density of blood flow ultrasonic Doppler signal using wavelet analysis. Method Doppler signal of blood flow in human common carotid artery was studied with wavelet scalogram analysis, an affine smoothing Wigner Ville transform with a constant "Q" character. Result Wavelet scalogram of blood flow ultrasonic signal had a higher distinguishability than STFT spectrogram in the low frequency portion, but had poorer decussation terms than spectrogram.

对于平稳信号的处理工具仍然是Fourier变换，但是，在实际应用中的绝大多数信号是非平稳的，现在看来处理非平稳信号的主要工具将是小波变换，这主要是因为传统的Fourier变换分析信号时，时间和频率分辨率精度是固定不变的，而利用小波变换分析信号，在信号高频段时间分辨率精度也较高，在信号低频段频率分辨率精度较高，这很符合非平稳信号的特点。

Brain is a very complex non-linear system, and electroencephalograph and electrocorticogram are also non-stationary and nonlinear in nature, signal processing methods based on linear and stationary assumptions, although has obtained important result, can not grasp the entire picture of neuroscience.

人脑是一个高度复杂的非线性非平稳系统，所以脑电图和皮层脑电图也是非线性非平稳信号，基于线性和平稳假设的分析方法尽管取得了一些重要的研究成果，但是无法对神经系统进行更加深入的解释。

Furthermore, based on the ergodic theory of Markov process we analyze the stationary distribution of network residual series, and prove the efficient conditions under which the unique asymptotic stationary distribution exists.

同时，根据马氏过程的遍历理论，对网络输出残差的平稳条件进行了研究，证明了网络输出平稳残差的充分条件，给出了残差序列存在唯一的渐近平稳分布的条件。

The non-stationary index of automobiles\' supporting force response under side wind is analyzed, which confirms the reasonableness of stationary assumption in dynamic reliability analysis.Thirdly, joint distribution of wind speed and wind direction is established based on the extensive extreme value distribution, which is used for reliability analysis of bridge traffic safety.

其次提供了Fourier变换识别抖振响应频谱失真的实例，采用Hilbert-Huang变换分析桥梁抖振响应的时频特性，从结构动力学角度探讨了响应非平稳性的原因，从风工程的角度探讨HHT变换分量的物理意义，并分析侧风作用下桥上汽车支撑力响应的非平稳指标，为动力可靠度分析中平稳性假定的合理性提供必要的论证。

A model for finding the cryptic period of hydrological time series is proposed. The functions of the model include to apply logarithm transformation for making the sequence more stationary, to construct a corresponding auto-regression model for reducing the herteroskedasticity of residual, to determine the component of the prime period by periodogram analysis.

本文在讨论水文时序平稳性和异方差性的基础上，提出了检测水文时序隐含周期的模型，即对水文时序设计对数变换序列，提高序列的平稳性；建立相应的自回归模型降低残差的异方差性；通过对所得平稳序列进行周期图分析确定可能的主周期分量。

Model for finding the cryptic period of hydrological time series is proposed. The functions of the model include to apply logarithm transformation for making the sequence more stationary, to construct a corresponding auto-regression model for reducing the herteroskedasticity of residual, to determine the component of the prime period by periodogram analysis.

bstract 本文在讨论水文时序平稳性和异方差性的基础上，提出了检测水文时序隐含周期的模型，即对水文时序设计对数变换序列，提高序列的平稳性；建立相应的自回归模型降低残差的异方差性；通过对所得平稳序列进行周期图分析确定可能的主周期分量。

In the aspect of the study of the application of HHT method, This dissertation has done three part of jobs: first, the Elcentro strong ground motion which is in common use in earhtquake engineering is analyzed by HHT method, getting its amplitude-frequency-time distribution and the comparison between the HHT marginal spectrum and Fourier spectrum is also made; second, the typical nonlinear system defined by the Duffing equation is analyzed by HHT method, getting its numerical value's amplitude-frequency-time distribution and the comparison between the HHT marginal spectrum and Fourier spectrum is also made; third, define the stationary degree of non-stationary signals making use of 3-D time-frequency spectrum and marginal spectrum, the stationary degree curve of Elcentro seismic recording is protracted according to its defining formula, the stationary degree curve of Elcentro seismic recording which change with time is protracted according to similiar definition.

在HHT方法的应用研究方面，本文做了三部分的工作：首先，利用HHT方法分析了地震工程中常用的Elcentro非平稳强震记录，得到了该记录的振幅－频率－时间分布特性，并将得到的边际谱与傅立叶谱做了比较；其次，应用HHT方法分析了典型的非线性系统－Duffing方程，得到了该方程数值解的振幅－频率－时间分布特性，并将得到的边际谱与傅立叶谱做了比较；最后，利用三维时频谱与边际谱定义了非平稳信号的平稳度，并依照其定义式绘制了Elcentro地震波记录的平稳度曲线，依照类似与依赖与频率变化的平稳度定义，初步尝试编程绘制了Elcentro地震波随时间变化的平稳度曲线。

The correlation coefficient stationary process in which the mean and variance vary with time is familiar in engineering,and the traditional correlation function stationary process is just a special case of that.

相关系数平稳过程是从非平稳过程中分离出的一类工程上常见且便于研究的随机过程，其均值和方差都可随时间变化，传统的平稳随机过程是它的一个特例。

On the assumption that the unevenness of runway profiles along the direction of taxi - ing is a stationary random function,techniques of piecewise constant-speed taxi ing runs and piecewise linear representation of dynamic properties of airplane landing gears are adopted in this paper to approximately simplify the actual nonlinear and nonstationary random vibration prob-lems to the piecewise linear and stationary ones.

在飞机滑行方向跑道路面不平度为平稳随机函数的假设下，采用滑行过程分段等速化、起落架动态特性分段线性化方法，把原非线性非平稳随机振动问题，简化为分段线性平稳随机振动问题。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷