查询词典 frequency analysis

Matlab Toolbox time-frequency analysis, with short-time Fourier transform, Cohen category bilinear time-frequency processing function, Affine category bilinear time-frequency processing function, Fuzzy function and the other handling functions such as source, it should be very useful.

Matlab 时频分析工具箱，含短时傅立叶变换、Cohen类双线性时频处理函数、Affine类双线性时频处理函数、模糊函数和其他处理函数等源码，应该很有用。

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。

Methods: A retrospective study was conducted using an insurance database from Bureau of Nation Health Insurance - Central regional branch with registered children born in 2001 who received teeth fluoridation and anti-decay program. The difference of utilization of dental care preventive service analysis was based on each individual child's character and required dental treatment. For cost-benefit analysis, children were selected who were eligible receiving or non- receiving this benefit from July 1, 2004 till 2007. Two groups were compared by frequency matching analysis, based on sex, medical provide territories, insured fee. Additional Incremental benefit/cost method of cost-benefit analysis is also conducted to evaluate the service providing cost increasing and dental treatment cost decreasing effectiveness.

研究方法主要系透过健保局中区分局93年至96年儿童牙科医疗费用统计资料，比较90年次出生之儿童接受涂氟预防保健服务之人口学特质及其涂氟前后牙科医疗利用差异；并依该等对象接受涂氟预防保健服务与否区分两组，就其性别、就医地区别与全民健保投保金额组别等予以配对，进一步应用成本效益分析（cost-benefit analysis，CBA）之增量益本比（Incremental benefit/cost method，IBC），探讨儿童牙齿涂氟预防保健服务成本的增加，使牙科医疗费用减少所带来效益的增加为何。

In consideration of the features of gearwheel drive box faults of the horizontal rotary screen roller printer and the basic principle of reversal frequency analysis and its advantages in failure diagnosis , reversal frequency analysis is adopted in fault diagnosis of gearwheel drive of the printing machine and better results are obtained.

介绍了卧式圆网印花机齿轮传动箱故障的特点以及倒频谱分析的基本原理和在故障诊断中的优点。

Chapter 5 indicates that multi-scale time-frequency analysis such as wavelet and EMD could offer more information of HRV than traditional linear analysis ways in time domain and frequency domain, which is a research trend with those nonlinear ways.

第五章将从研究方法上指出以小波分析和EMD为代表的多尺度时频分析可以比通常的HRV时频分析方法揭示更多的信息，和非线性动力学分析一起成为HRV分析的发展方向。

The wavelet time-frequency properties of the uncracked rotor and the cracked rotor were discussed by the continuous wavelet time-frequency analysis algorithm. A new algorithm using the wavelet time-frequency analysis algorithm to detect the crack was proposed. The influence of the sampling frequency on the wavelet time-frequency analysis algorithm was analyzed through the numerical simulation research; the valid sampling frequency was presented.

利用连续小波时频分析方法，讨论了裂纹转子与无裂纹转子的小波时频特性，提出了利用小波时频分析方法识别裂纹的新方法；数值仿真研究了采样频率对小波时频分析方法的准确性和有效性的影响，并给出了建议性的采样频率。

Joint Time-Frequency Analysis is a new-style theory in Signal-Analysis, which combines the signals' characters in time domain with those in frequency domain. For reflecting the integral character, JTFT possesses good effect in analyzing unstationary or time-changing signals.

联合时频分析方法是一种新型的信号分析理论，它结合了信号在时间域与频率域的特性，反映了信号频率随时间变化的综合特性，在分析非稳定、时变信号方面具有很好的效果。

In this paper Ⅰ successfully applied these methods to fault diagnosis, and presenting some new innovative machinery fault diagnosis method; First Ⅰ present a new gear wornout fault diagnosis method, this method use the vibration signal's time-frequency attribute and instantaneous phase undulation to accurately detect gear's fault, and by comparing with the traditional frequency domain analysis method, this method reveals that many nonlinear and nonstationary characteristic exist in gear's vibration, this tell us that if we use frequency domain analysis method without pay attention to the signal's characteristic, we could get wrong diagnostic result; Then Ⅰ present a new bearing fault diagnosis method, this method use ATVFD and Hilbert transform to do envelop demodulation,Ⅰ analyze the envelop with time-frequency method and find out that this method is more accurate then traditional method.Ⅰ also explain that the modulation of the fault to the carrier wave may also be non-stationary and nonlinear; Finally Ⅰ present a cylinder pressure measurement method of diesel engine by means of vibration, cylinder pressure is an important parameter of diesel engine fault diagnosis, the pressure measuring is simplified a lot by this method,Ⅰ also use the ATVFD and time-frequency analysis to realize it.

本文中将上述理论方法成功地应用到故障诊断中去，提出了几点创新性的诊断方法；提出了一种齿轮磨损故障诊断的新方法，该方法利用振动信号能量的时频域分布特征与瞬时相位波动特征可以进行精确的齿轮故障诊断，并通过与传统的频域诊断方法的比较，揭示出齿轮振动中存在的明显的非线性与非平稳特征，说明了不加选择地利用频域分析方法进行齿轮故障诊断很可能会得到错误的诊断结果；提出了一种轴承故障诊断的新方法，该方法利用ATVFD分解与Hilbert变换进行包络解调，并对解调得到的包络信号进行时频域分析，可以实现更加准确轴承故障诊断，说明了故障对载波信号的调制往往也是非平稳与非线性的；提出了一种利用振动信号进行柴油机汽缸内压力检测的新方法，柴油机汽缸压力的变化是柴油机故障诊断的重要参数，利用振动方法可大大简化汽缸压力的检测过程，该方法也是综合利用ATVFD分解与时频域分析方法实现的。

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。

Time-frequency analysis tool kit for learning the time-frequency analysis is a very good help.

详细说明：时频分析的工具包，对学习时频分析的是一个很好的帮助。

Graf, without question, is the greatest women's player in history.

格拉芙，现在，毫无疑问是女子网坛历史上最伟大的选手。

If not, you will have to look around at all your important data.

如果没有，您将需要检查所有的重要数据。