低频

Seven experiments were conducted in the present study to test and verify two inferences:(1) In character decision performance, high frequency character have not character stroke and component number effect, but low frequency character is an essential condition to stroke and component number effect;(2) In prime condition, when SOA is very short (SOA=56ms), component character can prime the recognition of low frequency compound characters, but failure to prime the high frequency compound characters.

在此基础上，本文通过7个行为实验验证了这一假设的两个重要推论：(1)在字决定任务中，高频汉字不存在部件数和笔画数效应，而低频字不必然存在笔画数和部件数效应；(2)在启动条件下，当SOA较短（=56毫秒）时，成分字仅对低频合体字有启动效应，而对高频合体字没有启动效应。

Projectile's radial acceleration sample value in trajectory includes projectile's angular velocity information and air drag acceleration,to extract angular velocity-time series value,the design method of the FIR digital filter firstly uses Matlab to design and emulate,and then on the float-point of DSP digital filtering is realized.

旋转弹丸外弹道离心加速度采样信号包含有高频弹丸转速信息和空气阻力加速度低频分量，为了提取弹丸转速－时间序列值，需要实时滤除低频阻力加速度分量，设计了在DSP中实时实现的数字滤波器。

The influence of low-frequency electromagnetic field on microstructure and morphology of primary Si particles of Al-19.2% Si alloy ingot specimens prepared by semicontinuous casting process was investigated with electronic optical microscopy, where the specimens were taken from different parts of the cast to which different electromagnetic fields are applied.

采用低频电磁半连续铸造技术制备Al-19.2% Si合金铸锭，利用电子光学显微镜对铸锭的显微组织进行分析比较，研究了电磁场强度和频率对初生硅颗粒形貌的影响；利用测温技术对合金的凝固过程进行监测，研究低频电磁场对凝固前沿温度场的影响。

It is proved that the control system with the filter of the low-frequency oscillations preserved the separation principle between the poles of control systems and that of the observer.

将低频振荡滤波器应用于电力系统中汽机侧的控制过程，实现对低频振荡的快速，有效削减和抑制，提高了系统的调频精度。

When it is applied to pipeline noise elimination and panel sound absorption, the bandwidth will be much wider than one Helmholtz resonator.

研究了一类低频宽带共振吸声结构，该结构由多个带伸长瓶颈的亥姆霍兹共振器组成，可应用于管道消声和壁板吸声，达到低频宽带吸声的目的。

The results of the experiment confirm that the turbulence in the constant volume combustion bomb pulsates tempestuously and the main part of the energy of the turbulence in the experiment distribute in the field of the frequency lower than 200Hz.

实验结果表明定容燃烧弹内的湍流是剧烈脉动的高度非定常流动，其中包含的能量主要集中在200Hz以下的低频区域，大尺度湍流在低频区域的能量比小尺度湍流的能量大得多，而且其能谱密度的峰值也大，对应的频率则稍高一些。

In chapter 3, the mechanism of test table waveform distortion generated by all factors in ultra-low frequency standard vibrator is studied systematically for the first time. First, the expression of suspension spring is obtained according to the experimental results.

首先阐述了振动传感器的特点及其校准方法，指出了建立超低频标准振动计量的迫切性和重要性；然后回顾了国内外标准振动计量技术的研究概况；接着指出了超低频标准振动计量存在的问题并指明了研究方向，另外，还对标准振动计量中的自动控制研究情况进行了回顾和评述；最后指出本论文研究的主要内容。

Then the creative research work on ultra-low frequency and large amplitude elcectromagnetic vibrator based on moving magnet is done, improving exciting signal at ultra-low frequency, and, the theoretic analysis and experiment model are studied. Thus, the reference for establishing ultra-low frequency standard vibrator in future is provided. In chapter 5, two control strategies for ultra-low frequency standard vibrator test table waveform are studied.

首先采用机械振动隔振理论，研究设计了机械低通滤波器来滤除噪声信号，并运用等效的小振级信号进行了实验研究，得出了有益的结论；然后为提高超低频时激振信号，作者创造性地提出了动铁型大位移的电动振动台结构，进行了理论分析和实验模型研究，为将来建立大位移的超低频标准振动台提供了参考。

The curve obviously declined from the low frequency to the middle frequency section, and was reduced to zero in the high frequency section, which objectively showed the change in imaging characteristics of the eyes from the low to high frequency areas.

PSF分析系统可直接采用屈光系统MTF曲线表达人眼的成像特征，该曲线MTF值从低频至中频迅速下降，高频趋向缓和至零，定量并客观地表达了人眼成像质量从低频至高频的改变。

Cavitation is the most distinct characteristic of the high-power low-frequency ultrasonic fields, and it is also regarded as the primary mechanism of ultrasonic cleaning. Nevertheless, the measurement question of the high-power low-frequency ultrasonic fields hasn't been resolved well, because of the incomplete cavitation theory and the complexity of cavitation fields. The universal acceptant standard measurement hasn't been found up to the present so that it is difficult to judge of the performance of ultrasonic cleaning machines scientifically.

大功率低频超声场最鲜明的特点就是空化，而空化也被认为是超声清洗的主要物理机制，但由于其理论研究尚不完善，加之空化声场的复杂性，使得至今大功率低频超声场的测量未得到很好的解决，尚未找到一种与清洗效果有确定关系的普遍适用的标准方法，使得在客观地评判清洗机优劣时很困难。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失