查询词典 frequency conversion

A new frequency estimation algorithm for Time Domain Synchronization OEDM system is proposed, which utilizes the time domain circular characteristic of PN sequences to adjust frequency offset and then uses a variable step frequency scan scheme to estimate large frequency offset.

提出一种新的适用于TDS-OFDM系统的频偏估计算法，利用PN序列的时域循环特性进行预频偏调整，然后用变步长扫频进行大频偏的估计，定时同步之后再利用PN的时域循环特性进行细偏估计。

Below us Divider VHDL description of the source code for the completion of the clock signal CLK frequency of 2 hours, 4 frequency, frequency of 8 hours, 16 minutes frequency.

下面我们介绍分频器的 VHDL 描述，在源代码中完成对时钟信号 CLK 的 2 分频， 4 分频， 8 分频， 16 分频。

To review the basic terminology in data organization and data presentation 2 To learn frequency distribution and cumulative frequency distribution 3 To construct the graphical representations: histogram, frequency polygon, and culmulative frequency polygon

回顾数据组织及数据表达的基本用语。学习频数分布及累积频数分布。绘制如组织图、频数多边形及累积频数多边形等的图示。

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。

So the frequency of pulse drive mode amounts to the frequency of external signal, and the operate frequency of driver should be below the frequency of MOSFET.

本论文所涉及的工作对半导体激光器的广泛应用具有积极意义，它解决了半导体激光器应用中存在的关键问题。

To further understand and correctly master the notion of marginal spectrum in Hibert-huang transform, the linear property of marginal spectrum is demonstrated, an mistake to the notion of marginal spectrum in some documents is pointed out, and a new viewpoint about the essential difference between marginal spectrum and Fourier frequency spectrum is put forward by which the amplitude of Fourier frequency spectrum only represents the probability that a frequency objectively exists in a signal while the amplitude of marginal spectrum decides whether a frequency objectively exists in a signal.

为了深入理解和正确掌握希尔伯特－黄变换（Hilbert-Huang Transform，简称HHT）中的边际讲概念，证明了边际谱的线性性质，指出了文献中对边际谱概念的一种误解，提出了边际普与Fourier频谱之间本质区别的一种的新观点，即Fourier频谱的幅值只能反映频率在信号中实际存在的可能性大小，而边际谱的幅值则能真实反映频率在信号中是否存在。

Vertically put the KAS detector on the upper part of the transmitter cover, turn EAS detector power supply switch on, EAS detector displays radio frequency output center frequency is: 8.2±0.05MHz; Adjust R15 (counterclockwise decrease, clockwise increase) can change radio frequency output center frequency.

把 EAS 检测仪垂直放置于发射机壳上部，按动 EAS 检测仪电源开关， EAS 检测仪显示射频输出中心频率为：8.2±0.05MHz ；调节 R15（反时针减少、顺时针增大）可改变射频输出中心频率。

The paper introduces application of frequency speed control ler on high-voltage plunger pump from frequency control moter speed theory,frequency speed contrcller volume defined and model selection,controlling optimizing and frequency speed control ler's installation,using,keeping.

从变频调速原理、变频调速器容量确定及选型、控制方式优化及变频调速器的安装、使用、维护等方面入手，介绍了变频调速器在高压柱塞泵上的应用情况；并总结出了处理变频调速下电机发热的方法；最后，对变频调速器的优越性能及节能效果进行了分析计算。

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。

The noise frequency modulation signal was particularly analyzed. The Fokker-Planck equation of noise frequency modulation was presented and the Motion-Group Fourier Transform was used by converting the partial differential equation into the variable coefficient homogenous linear differential equations. Then the solutions were given by using the peano-baker series. So the probability density function of noise frequency modulation in the filter was given. On the basis of the probability density function the stochastic resonance of noise frequency modulation signal is analyzed.

首先建立了噪声调频干扰信号通过脉冲压缩雷达中频滤波器后所满足的福克尔－普朗克方程，然后利用群移傅立叶变换（Motion-Group Fourier Transform，MGFT）将此偏微分方程化成了变系数齐次线性微分方程组，并利用Peano-Baker级数法给出了该方程组的解，最后得到了噪声调频干扰信号通过脉冲压缩雷达中频滤波器后的概率密度函数，在此基础上研究了噪声调频干扰信号造成的随机共振现象。

The father that if work,mad father, love annoys, disposition is too indrawn the be short ofing that the father of Mu Ne, resign oneself to adversity causes father easily to love is broken; Communicate time effectively between father and son, Mu Zizhi to be less than a hour on average to wait a moment every week, it is the cause that causes the child to become addiction.

如工作狂的父亲、爱愤怒的父亲、性格过于内向木讷、逆来顺受的父亲都易造成父爱的缺失；父子、母子之间的有效沟通时间每周平均小于一小时等等，都是造成孩子成瘾的原因。

These are vandal proof and they come with a locking mechanism.

这是野蛮的证据，他们来到了锁机制。