高频率

Results The tinnitus frequency, severity of subjective tinnitus, audiogram types and some items of function test above hearing threshold were significantly different in the five groups (P.05). Specific features of pure-tone test were found in the five groups: tinnitus frequency was low, whole- frequency hearing threshold high, audiogram even, short increment sensitivity index at 1 kHz high and tone decline at 4 kHz low in the syndrome of invasion of wind-heat; tinnitus frequency was high, high-frequency hearing loss common, audiogram abruptly descending, SISI and TD at 4 kHz high in the syndrome of liver-fire up-stirring; subjective tinnitus was loud, audiogram abruptly descending or gradually descending, SISI and 7W at 4 kHz low in the syndrome of stagnation of phlegm-fire; tinnitus frequency was high, subjective tinnitus low, audiogram markedly descending or hill-like, SISI and TD at 4 kHz high in the syndrome of kidney-essence deficiency; average hearing loss was less, audiogram irregular but abruptly descending or notched in most cases, SISI at 4 kHz low in the syndrome of weakness of spleen-stomach.

结果］耳鸣频率、自觉耳鸣程度、听力图类型及部分阈上功能测试指标在各证型间具有显著性差异(P.05)，这些指标在不同的证型中表现出不同的特点：风热侵袭型的耳鸣频率较低，全频听阈升高，听力图多为平坦型，短增量敏感指数得分在1kHz较高，而4kHz音衰值较低；肝火上扰型的耳鸣频率较高，听力损失以高频为主，听力图多为陡降型，4kHz SISI得分及TD值均较高；痰火郁结型的自觉耳鸣响度较大，听力图以陡降型或缓降型为主，4kHz SISI得分及TD值均较低；肾精亏损型的耳鸣频率较高，而自觉耳鸣响度较低，听力图以显降型或山型为主，4kHz SISI得分及TD值均较高；脾胃虚弱型的平均听力损失较小，听力图无一定规律性，但以陡降型或切迹型为主，4kHz SISI得分较低。

One of the most common ways to describe a wood's tonal properties is in terms of its frequency range,which is often broken down into low-end frequencies,mid-range and high-end frequencies.picture it as a visual spectrum,as we've done in the chart to the right,with the lower frequencies on the left and the higher frequen-cies on the right.the graph line for each wood visually depicts its general tonal range.rosewood and ovang kol,for example,tend to resonate with more low-end frequencies,whereas koa,cocobolo and maple tend to sound brighter from having more top-end frequencies.note also rosewood's"scooped"midrange and ovang-kol's fuller midrange.the doted lines for walnut and koa denote the expansion of low-end frequency range as the guitar opens up after a period of playing it.

最常见的方式描述了木材的声音特性是在其频率范围内，这往往是细分为低端频率，中端和高端frequencies.picture它作为一个视觉频谱，因为我们'维生素E这样做的图表，以权，以较低的频率在左边和更高的频率，种上right.the图线的每一个木材视觉描绘的一般音调range.rosewood和ovang科尔举例来说，往往会产生共鸣更多的低端频率，而兴亚， cocobolo和枫树往往从健全光明有更多的高端frequencies.note也花梨木的"收购"的中端和ovang -科尔的充分midrange.the doted线的核桃和兴亚指扩大低端频率范围内的吉他开辟了一段时间后，打它。

The effect of tribology factors on bearing vibration is studied experimentally. AR model and WPT are used to processing the normal arid abnormal signals. The results are as follows:1. The vibration of ball bearings is caused by the tribology action of contact pairs of ball and ring races and has the essential of tribo-dynamics. Any factors affecting the tribology characteristics of contact pairs will affect vibration and noise of bearings consequently.2. Vibration characteristics of bearing keep almostly unchanged with the increasing of axial load expecting the increasing of nature frequencies. When radial load increasing with axial load unchanged, nature frequencies keep unchanged but some new vibration peaks appears in the spectrum.3. Vibration amplitudes are damped and nature frequency are enhanced with sufficient lubrication. Vibration and noise of bearings increase obviously and roar can happen and the contact surfaces scratch slightly under insufficient and unclean lubrication state. Bearing will be disabled in a few minutes without any lubrication.4. Bearing vibration is unstable under low speed. With the speed increasing, the vibration become stable and natural frequencies increase slightly but the amplitudes increase apparently.5. Bearing vibration can be excited only by some harmonics ofwaviness without lubrication and by all harmonics with lubrication based on the theoretical analysis.6. The nature frequencies of ball bearings decrease with the increasing sizes. When international clearance increasing, nature frequencies decrease in radial and increase in axial and angular and the amplitudes increase in radial and decrease in axial and angular. When the number of balls increasing, nature frequencies increase and amplitudes decrease. When the pitch diameter increasing, axial nature frequency increase and others nearly keep no change. When outer race groove curvature radius increasing, nature frequencies increase in radial and decrease in axial and angular and amplitudes keep no change in radial and increase in axial and angular. When inner race groove curvature radius increasing, nature frequencies decrease and amplitudes increase.7. The distortion in amplitude and frequency components of bearing vibration signals picked up by the present probe measurement method is founded and right conclusions cannot be achieved by the signals. When accelerometer is rigidly screwed with steel stud onto a flat outer surface of a ball bearing, vibration signal can be got without distortion and the reliability of research on bearing vibration is assured.8. AR model is suitable for large samples of bearing vibration signals, square root of length of samples can be used as the upper limitation of order determination and the FPE order selection criterion is effective. Many advantages of AR spectrum are founded over the classical based on FFT.9. Time-Frequency analysis is necessary for abnormal noise of ball bearings. WPT overcomes the principle shortcomings of STFT and proved to be a best tool to process the abnormal signals.

理论分析和试验研究表明： 1球轴承振动是钢球—滚道接触副中的各种摩擦学作用引起的，具有摩擦动力学的本质，任何对接触副的摩擦学特性有影响的因素都将对球轴承的振动和噪声特性产生影响； 2中心轴向载荷作用下，载荷增大使球轴承的固有振动频率升高，载荷越大同样的载荷增幅引起的频率升幅减小，足够大的中心轴向载荷作用下载荷的变化对球轴承振动的频率特性不会产生明显的影响； 3轴向和径向联合载荷作用下，径向载荷不大时球轴承振动的固有频率基本不变，但是可能引起变刚度激励的非线性振动，出现新的频峰，过大的径向载荷将使部分钢球脱离接触，使球轴承的振动和噪声呈现不稳定状态； 4润滑对球轴承的振动和噪声特性有重要的影响，良好的润滑对振动有明显的抑制作用，润滑不充分时，振动和噪声的水平会有明显增高，一定条件下还会激发接触副中的谐振，发出啸声，造成接触表面的伤害，无润滑干接触时，短时的运转就会损伤接触副表面，使振动和噪声迅速增大，并随时可能引发严重的磨损和卡滞失效；接触副润滑良好时，油膜的"刚化效应"使球轴承振动的固有频率有所提高，润滑剂中含有弥散性污浊时，振动的幅度总体升高，但弥散性污浊不会改变球轴承振动的频率特性；浙江大学博士学位论文：球轴承振动的研究 5低速时，球轴承振动的基本特征呈现不稳定状态，随着转速的提高，球轴承振动的频率特性趋于稳定，固有频率频峰升高； 6理论分析表明，干接触时钢球和滚道表面波纹度的某些谐波分量能激励球轴承的振动，振动的幅值与谐波幅值成正比，实际球轴承中钢球的分布不可能完全均匀，波纹度的激励作用会随时发生；润滑接触的分析表明，波纹度的任意谐波分量均能激励球轴承的振动； 7球轴承的几何和结构参数分析表明，球轴承尺寸越大，径向、轴向和角振动的固有频率越低；钢球中心圆直径增大，球轴承的径向和轴向振动的固有频率基本不变，角振动的固有频率有所上升，振动的幅频特性基本不变；径向游隙加大使球轴承的径向振动固有频率降低，轴向和角振动的固有频率有所升高，径向振动幅频特性的幅值升高，而轴向和角向降低；钢球的数量增多使球轴承振动的固有频率上升，幅频特性的幅值下降，径向振动的幅值下降最为明显；外圈沟曲率半径系数增大使球轴承径向振动的固有频率升高，轴向和角振动的固有频率降低，径向幅频特性基本不变，轴向和角向幅频特性幅值升高；内圈沟曲率半径系数增大使径向、轴向和角振动固有频率均下降，振动幅频特性的幅值均有升高； 8试验对比表明，传感器采用探针式安装时，由于探针接触副接触特性的影响，钡(量得到的球轴承振动信号有失真，采用专门设计和制作的试验球轴承，以固定式安装加速度计，首次测量得到了球轴承振动的真实信号，通过对振动信号的分析，验证了球轴承振动的理论模型； 9)基于时间序列分析的AR模型适用于大样本球轴承振动信号的分析，以样本长度的均方根值作定阶上界，FPE做判阶准则，给出的AR谱光滑，频率分辨率高，是球轴承振动分析的简便而可靠的手段； 10以时频域分析的小波包变换分析球轴承异音信号能够比较好地定位和聚焦异音发生的时间，时间间隔，频率范围，同样是球轴承振动分析的可靠的手段，可用作球轴承故障诊断技术。

As a differential detection is used between the intercarrier, the proposed algorithm overcome the high sensitivity to timing error of conventional algorithm and is robust to multi-path. The effect of sample frequency offset can't be ignored in a continuous OFDM system of a large number of subcarriers. The estimation precision of the conventional algorithm is low and the realization is complex. A joint estimation of sample frequency offset and fine frequency offset based on difference operation is proposed. As averaging use a large number of samples in a maximum likelihood algorithm, the estimation precision is very high. The use of difference operation cancel the effect of carrier frequency offset, and the proposed sampling frequency estimation algorithm is robust to carrier frequency offset.

最后，本文对连续系统中的采样频率和载波频率精同步技术进行较为深入的研究，由于子载波数目大的连续OFDM传输系统中，采样频率偏差不可忽视，以往的采样频率估计方法精度低、实现复杂，因此本文提出了一种基于差分处理的采样频率偏差和精载波频率偏差联合估计算法，利用了最大似然算法进行采样频率偏差的估计，由于采用了差分处理方法，消除了载波频率偏差对采样频率偏差估计的影响，采用的最大似然算法对大量样点进行平均化处理，所以，相对以往算法，提出的联合算法估计精度高，而且采样频率偏差估计对载波频率偏差具有鲁棒性。

One of the most common ways to describe a wood's tonal properties is in terms of its frequency range,which is often broken down into low-end frequencies,mid-range and high-end frequencies.picture it as a visual spectrum,as we've done in the chart to the right,with the lower frequencies on the left and the higher frequen-cies on the right.the graph line for each wood visually depicts its general tonal range.rosewood and ovang kol,for example,tend to resonate with more low-end frequencies,whereas koa,cocobolo and maple tend to sound brighter from having more top-end frequencies.note also rosewood's"scooped"midrange and ovang-kol's fuller midrange.the doted lines for walnut and koa denote the expansion of low-end frequency range as the guitar opens up after a period of playing it.

最常见的方式描述了木材的声音特性是在其频率范围内，这往往是细分为低端频率，中端和高端frequencies.picture它作为一个视觉频谱，因为我们'维生素E这样做的图表，以权，以较低的频率在左边和更高的频率，种上right.the图线的每一个木材视觉描绘的一般音调range.rosewood和ovang科尔举例来说，往往会产生共鸣更多的低端频率，而兴亚， cocobolo和枫树往往从健全光明有更多的高端frequencies.note也花梨木的&收购&的中端和ovang -科尔的充分midrange.the doted线的核桃和兴亚指扩大低端频率范围内的吉他开辟了一段时间后，打它。

The digital frequency source this paper researched uses high integrated DDS chip AD9851 as frequency sources and signal mirac processors AT89C51 as system control center, it can output 10Hz-20MHz signal with high-precision and high stability frequency. The evenness of signal within the range of 10MHz is low to 0.1dB degree, and the smallest step is low to 10Hz frequency.

本课题研究的数字频率源采用高集成度DDS芯片AD9851作为频率源；以单片机AT89C51作为系统的控制中心，实现了10Hz～20MHz的高精度、高稳定度的频率输出。10MHz内信号幅度的平坦度为0.1dB、频率最小步进为10Hz。

For frequency information fluid identification technology:the basic theory of fluid identification based on frequency information has been introduced,for inner and external factor affecting frequency,some steps have been proposed to attain reserved amplitude and frequency analysis data with high resolution,high S/N ratio;through the comparison of time-frequency analysis method, the high accuracy time-frequency analysis method has been selected to extract time-frequency attributes;the analysis method flow of common single frequency fluid identification has been proposed,according to the data of full frequency band,several anomaly zone modes of common single frequency attribute have segregated; incorporating converted wave and compression wave,fluid identification method based on PS wave combined time-frequency analysis has been proposed;the AVO property of various fluid type in frequency domain has been studied;the generalized fourier analysis method,Proni absorption filter has been introduced,and researched for anti-noise and for the seismic processing interpretation flow.The above technology have been applied to fluid identification of organic reef in WBT area in the east of Sichuan and fluid identification of clastic rock in GUANGAN area in the middle of Sichuan,the results show that the above methods are effective.

基于频率信息的流体识别技术方面：介绍了利用频率信息流体识别的基本理论，针对影响频率的内、外在因素，提出一些针对措施，以获得高分辨率、高信噪比的保幅、保频分析数据；通过时频分析方法的比较，选取高精度的时频分析方法提取时频属性；提出共单频属性进行流体识别的分析方法流程，结合全频带数据，分出几种共单频属性异常带模式；联合转换波资料和纵波资料，提出基于纵横波联合时频分析进行流体识别方法；研究了频率域内不同流体类型AVO现象；引进一种广义傅立叶分析方法：Proni吸收滤波，研究其抗噪性以及进行地震处理解释的流程；将这些技术应用川东北五百梯区块进行生物礁储层流体的识别和川中广安陆相碎屑岩的流体识别，取得较好的效果。

If phones really do cause cancer, but only at high exposure, employing such a generous definition of regular use means that the effect might be diluted into undetectability.

如果手机真的引发癌症，但只有在高频率使用才能致病。应用这样一个定义作为常规使用意味着这种影响被冲淡到无可检测的地步。

The results calculated show that the major contributions for the backscattering cross section come possibly from average cloud diameter, clear-air and humidity turbulence and also from distributions of cloud particles, especially, at higher frequencies.

再分析了云的后向散射机理，计算了西安地区云的后向散射截面；表明影响云的后向散射截面的主要因素为云滴平均半径、大气湿度湍流及云粒子分布，在较高频率时更显著。

I heard it on VHF last night.

我昨晚在特高频率广播中听到那件事。

Finally, according to market conditions and market products this article paper analyzes the trends in the development of camera technology, and designs a color night vision camera.

最后根据市场情况和市面上产品的情况分析了摄像机技术的发展趋势，并设计了一款彩色夜视摄像机。

Only person height weeds and the fierce looks stone idles were there.

只有半人深的荒草和龇牙咧嘴的神像。