高频率的

Researched influence of frequency on characteristic of electromagnetic wave transmission in tunnels, and analyzed characteristic of electromagnetic wave transmission in circular, arches and curved tunnels by method of metal wave guide, and gives approximate formulas of attenuation rate. Main conclusions we obtain are as follows: in circular,rches tunnels, if frequency is higher, attenuation rate is smaller, it is beneficial for EM waves to transmit, in curved tunnel, higher frequency, more attenuation rate ...

研究了频率对井下电磁波传输特性的影响，采用金属波导法分析了圆形、拱形及弯曲隧道中电磁波的传输特性并给出衰减率近似公式，得出主要结论：在圆形和拱形隧道中，频率越高，衰减率越小，越有利于电磁波的传播；在弯曲隧道中，频率越高，衰减率越大，不利于电磁波的传播；通过特性曲线与井下实验数据相比较得出在900MHz左右为井下无线通信系统传输信号最佳频段。

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。

With regard to the external Qinhuai River regulation project in Nanjing City, the inverse Gaussian distribution curve was determined as the flood level frequency curve of the river course by use of the frequency statistics technique, and the parameters λ and μ of the inverse Gaussian distribution were derived according to the current flood design standard.

结合南京市外秦淮河堤防整治工程，放弃传统的堤防潮位频率曲线线型，采用频率统计分析的方法确定了外秦淮河堤防潮位频率曲线的线型为反高斯分布；根据该堤防现行洪水设计标准推求了反高斯分布参数λ和μ。

In series capacitance,the low frequency is load resonance frequency.In parallel capacitance,the high frequency is load resonance frequency.

在串联电容时，负载谐振频率是两个频率中的较低的那个频率，而在并联电容时，负载谐振频率则是其中较高的那个频率。

Originally, higher input trigger frequency or lower input frequency for Viterbi Decoder were used to meet the transitions requirements.

因原本既有的标准，都是使用较高的输入频率来达成标准内的传输率，或者使用较低的输入频率，再用内部的PLL，提供出较高的触发频率给内部的维特比解码器来达成。

According to the consentaneous diagnostic criteria, divided the disease into Zheng patterns of TCM. Results 1 Female was predominated in IBS, compared with male. With the increase of age , the prevalence rate of IBS did not rise. The higher educational degree community had a higher morbidity of IBS than the community of the lower educational degree. Abdominal pain and discomfort are the symptoms, which more happened. Male and female did not show the distinction on the common symptoms.

结果 1IBS 女性患病率高于男性；患病率无明显年龄差异趋势；较高文化程度群体患病率高于较低文化程度的群体；腹痛及腹部不适是患者发生频率较高的症状；男性与女性在常见症状的发生频率上差异无显著性，但精神心理症状的发生频率上，女性应激事件发生率及抑郁状态发生率高于男性；肠道感染史、受凉、生冷饮食、辛辣饮食均为可能导致IBS发病的较危险因素；肠外症状中较常出现的为头痛、腰背痛、疲乏及功能性消化不良。

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。

In view of these shortcomings, this frequency meter has made the radical innovation in the design, its merit is: Uses the core component is the advanced monolithic special-purpose frequency measurement component -- monolithic frequency meter, the integration rate is high, the volume is small, consumes the electricity province, function, has realized the frequency meter high integration and the microminiaturization; So long as the monolithic frequency meter adds on the crystal oscillator, the measuring range choice, the frequency demonstrated and so on the very few components then constitute DC to the 10MHz miniature basic frequency measurement electric circuit; But the biggest merit was this frequency meter has realized monolithic frequency meter, frequency sampling electric circuit and the monolithic microcomputer three between hardware and the software connection completely, caused the frequency measurement measuring range the choice, the frequency data survey, the sampling as well as the code frontier transformation and the data dump possible monolithic microcomputer software programming automatically to carry on, thus has realized the frequency measurement and the sampling work intellectualizes completely, causes this system already to be possible to constitute a miniature intelligence to measure rate the instrument core electric circuit independently, also might take in the large-scale automatic control or a test system intelligent subsystem.

针对这些缺点，本频率计在设计上作了根本的革新，其优点是：所用核心器件是先进的单片专用测频器件——单片频率计，集成度高，体积小，耗电省，功能强，实现了频率计的高度集成化和微型化；单片频率计只要加上晶振、量程选择、频率显示等很少量的器件即可构成一个DC至10MHz的微型基本测频电路；而最大的优点则是本频率计完全实现了单片频率计、频率采样与单片微机三者之间的硬件与软件接口，使得测频量程的选择、频率数据的测量、采样以及编码的边境转换和数据的转储均可能过单片微机的软件编程自动进行，从而实现了测频与采样工作的完全智能化，使得本系统既可独立构成一个微型智能测率仪器的核心电路，也可作为大型自动控制或测试系统中的一个智能子系统。

In view of these shortcomings this frequency meter has made the radical innovation in the design its merit is: Uses the core component is the advanced monolithic special-purpose frequency measurement component -- monolithic frequency meter the integration rate is high the volume is small consumes the electricity province function has realized the frequency meter high integration and the microminiaturization; So long as the monolithic frequency meter adds on the crystal oscillator the measuring range choice the frequency demonstrated and so on the very few components then constitute DC to the 10MHz miniature basic frequency measurement electric circuit; But the biggest merit was this frequency meter has realized monolithic frequency meter frequency sampling electric circuit and the monolithic microcomputer three between hardware and the software connection completely caused the frequency measurement measuring range the choice the frequency data survey the sampling as well as the code frontier transformation and the data dump possible monolithic microcomputer software programming automatically to carry on thus has realized the frequency measurement and the sampling work intellectualizes completely causes this system already to be possible to constitute a miniature intelligence to measure rate the instrument core electric circuit independently also might take in the large-scale automatic control or a test system intelligent subsystem.

摘要传统的测频仪器体积很大，耗能量大，主要靠手工操作，而最大的缺点是不可编程，其量程转换、数据测量、采样控制和处理等均不能通过程序指令来进行控制，无法作为一个微型智能子系统与某一大型自动控制或测试系统进行接口。针对这些缺点，本频率计再设计上作了根本的革新，其优点是：所用核心器件是先进的单片专用测频器件——单片频率计，集成度高，体积小，耗电省，功能强，实现了频率计的高度集成化和微型化；单片频率计只要加上晶振、量程选择、频率显示等很晌慰的器件即可构成一个DC至10MHz的微型基本测频电路；而最大的优点则是本频率计完全实现了单片频率计、频率采样与单片微机三者之间的硬件与软件接口，使得测频量程的选择、频率数据的测量、采样以及编码的边境转换和数据的转储均可能过单片微机的软件编程自动进行，从而实现了测频与采样工作的完全智能化，使得本系统既可独立构成一个微型智能测率仪器的核心电路，也可作为大型自动控制或测试系统中的一个智能子系统。关键词高度集成化，单片机，频率计，电路

Adjust the pressure of the impact system steplessly, the strike energy of the hammer will also shift steplessly. When the pressure is higher, the strike energy is higher. When the pressure is lower, the strike energy is lower. Adjust the oil flow of supply pump steplessly, the strike frequency will also shift steplessly. When the flow is more, the strike frequency is higher. When the flow is less, the strike frequency is lower.

从而可通过无级调节控制冲击系统的压力，无级调节控制冲击器的冲击能，压力高时冲击能大，压力低时冲击能小；通过无级调节控制油泵供给冲击系统的流量，无级调节控制冲击器的冲击频率，流量大时冲击频率高，流量小时冲击频率低。

She gently rebuff ed him, but agreed that they could be friends

她婉言拒绝了，但同意作为朋友相处。

If in the penal farm, you were sure to be criticized.

要是在劳改农场，你等着挨绳子吧！