低频

At first, based on the results of the field tests and studies, this paper indicates that there are two kinds of low frequency power oscillations on the weak tie line: one is caused by negative damping, and belongs to the free oscillation; the other is caused by periodic load disturbances and periodic adjustments, and belongs to the forced oscillation.

首先，本文根据现场试验和研究结果指出，互联系统的弱联络线上存在两类性质不同的低频功率振荡：一类是由负阻尼引起的，属于自由振荡；另一类是由于系统周期性负荷扰动或振荡调节等引起的，属于强迫振荡。

The experiment shows that,there is phase drift of low frequency in the digital image seriel acquired by CCD camera and frame grabber,different CCD has different drift characteristic and level;the phase drifts are not identical even in the same image line,the phase drift of neighboring locations in an image line has distinct correlation;the drift levels ...

实验表明：经 CCD Camera和图像卡采集的数字图像序列中存在着低频的图像抖动，即位相漂移。而且不同的 CCD Camera具有不同的漂移特点和程度，甚至在同一个图像行内的漂移也不完全一致。一般在图像行内相近的位置之间，位相漂移有明显的相关性，不同的图像行之间的漂移的程度相同，但没有相关性。最后本文还给出了一种位相漂移的修正方法

Based on VHZ data recorded by 7 stations of China digital seismograph network for Nov. 14, 2001, earthquake in the west of the Kunlun mountain pass, we extracted spherical mode of 0S4-0S76 of the earth free oscillation using power spectral density estimation. Because the frequency response of seismograph in China digital seismograph network suppress information of solid tide, we do not need to remove the solid tide in our procession.

利用中国数字地震台网改造后的7个台站的VHZ波形资料，采用功率谱密度估计方法，利用中国数字地震台网地震仪对低频信号压制的特点，在没有对资料去除固体潮影响的情况下，提取了2001年11月14日昆仑山口西地震激发的0S4-0S76地球球型自由振荡，并与地球初步参考模型的理论自由振荡周期进行对比，结果表明与PREM预测的球型自由振荡周期符合得很好。

Objective To study effects of extremely low frequency magnetic field on brain function state during weightlessness.

目的 探讨极低频磁场在航天医学中的可能应用价值。

This is especially true in smaller rooms where a poor low frequency response is the main problem.

尤其是在较小的房间，一个贫穷的低频响应的主要问题。

Oceanographers Tatiana Ilyina and Richard Zeebe of the University of Hawaii, along with geochemist Peter Brewer of the Monterey Bay Aquarium Research Institute in California, report in the December 20 issue of Nature Geoscience that lowering the pH of the ocean by 0.6 units could decrease underwater low-frequency sound absorption by more than 60 percent.

在12月20日出版的《自然-地球科学》杂志上，夏威夷大学的海洋学家塔蒂亚娜·伊丽娜、理查德·齐伯和加州蒙特里海湾水族研究所的地球化学家彼得·布鲁尔报道说：海水的 pH 值降低0.6，深层水对低频声音的吸收会减少60%以上。

The graphs you show are measuring temporal variations in the geomagnetic field in the ULF (ultra-low frequency).

你显示的图表是量度磁场中的超低频的短暂变化。

We decompose curvature signal with wavelet at first and then extract itslow frequency coefficients as new smooth curvature signal, which is used to constructa G~2 continuous piecewise rational cubic Bezier curve with GHI method subsequently.

本文首先对估算得到的离散曲率进行小波分解，提取其低频部分作为新的曲率，然后利用几何Hermite插值方法，重建出光顺的截面线。

We decompose curvature signal with wavelet at first and then use its low frequency coefficients as new smooth curvature signal, which is used to construct a G^2 continuous piecewise rational cubic Bezier curve with (Geometric Hermite Interpolation, GHI) GHI method subsequently.

针对在逆向工程的实践中常见的轮廓线的光顺问题，给出了一种先对曲率图进行小波分解，提取其低频部分作为新的曲率图，并利用几何Hermite插值方法，生成G^2连续的分段三次有理Bézier曲线，从而重建出光顺的产品轮廓曲线的新方法。

During construction of our country's ultra-high voltage power grid, both electromagnetic loop circuit and stressed long UHV transmission passage may lead to low frequency power oscillation.

在我国特高压电网建设过程中，高低压电磁环网和重载的长距离特高压送电通道，都可能导致电网发生低频功率振荡。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。