查询词典 harmonics

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。

This article take the massive harmonics phenomenon as the language material, take the multi-gates discipline theory of the rhetoric, the language with study, the culture study, the glossary study, the dialectology, the psychology, the ethnology, the mark study, the embryology and so on as the instruction, uses classified, the induction, the comparison research technique, the discussion harmonics phenomenon production.

本文以大量的谐音现象为语料，以修辞学、语用学、文化学、词汇学、方言学、心理学、民俗学、符号学、发生学等多门学科的理论为指导，采用分类、归纳、比较的研究方法，探讨谐音现象生成的客观基础，总结其特性，分析其语用价值及社会功能。

Methods The effects of the reading error and the misalignment of the probes on the accuracy of measuring and all the harmonics of roundness were analyzed; The strategy and the algorithm for optimizing the parameters of the measuring system were proposed; The distribution and propagation patterns of the measured errors for all the harmonics of roundness were studied in detail; A software for correcting the errors caused by the measurement error of the angle positions of the probes and the sensitivity difference between three probes was presented.

分析了测头读数及角位置误差对圆度各次谐波及圆周各点测量精度的影响；提出了三点法测量系统的优化策略与算法；研究了三点法测量误差的分布与传递规律；提出了克服测头定位误差以及3个测头的灵敏度不一致影响的软件校正方法。

We research the spherical harmonics express of Lambert re- flection and propose a pure image based rendering method to synthesis image under arbitrary illumination condition based on spherical harmonics.

研究了朗伯反射的球调和表示，提出了一种基于球调和函数的任意光照目标图像生成方法。

The paper first introduces the basic knowledge of power system harmonics, and points out the importance of studying harmonics.

本文首先介绍了电力系统谐波的基本知识，并指出了电力系统谐波研究的艰巨任务和重大意义。

Results show that dominant periods of relief variation can be derived by periodogram more obviously and easily than by harmonics analysis,while harmonics analysis can obtain relief variation simulation models as well as its periods.

相比较而言，周期图分析可以更加直观地得到满足显著性检验的分布周期，但谐波分析还可以根据周期检验结果，得到对应的谐波模型。

A new strategies for restraining harmonics are presented in the paper, the methods adopt the right carrier frequency and the sine wave superimposed a proper three-time harmonics to make it saddle-shaped wave, produce SPWM waveform to control the inverter switching devices for the on and off .

并提出了一种新的易于工程实现的谐波抑制策略，该方法通过正确选择载波频率和在正弦调制波上叠加一个三次波使之成为鞍形波，产生相应的SPWM波形来控制逆变器开关器件的通断从而改善输出波形。

Simulation results of the circuit with filter indicate decrease of the harmonics in current of power supply, and the waveform is close to sinusoidal wave, which prove correctness of the solution to harmonics pollution.

本论文在此基础之上进行了电力滤波器的设计，在原电路中加入设计好的滤波器再次进行仿真，仿真结果表明，设备电源电流中的高次谐波含量大大减少，波形很接近正弦波，这证明了谐波治理方案设计的正确性。

In this paper, a sort of recursive formulas of spherical harmonics integrals, which often appear in the gravitational gradient harmonic analysis, are deduced according to the recursive formulas between every other order of spherical harmonics and the trigonometric functions＇properties. And the calculated formulas on the recursive initialization also are brought forward.

本文根据球谐函数的跨次递推公式和三角函数的性质，详细推导了在重力梯度调和分析中出现的一类球楷函数积分的跨次递推公式和递推初始值的计算公式。

The simulated climate fields were decomposed with the spherical harmonics function and the corresponding spectral analysis was made,thus the spherical harmonics feature of global 500 hPa height and the sea level pressure in several truncations was investigated and the field changes on doubling CO2 were analyzed too.

对模拟的气候场用球谐函数作波谱分析，得到了全球500hPa高度和海平面气压在不同截断时的波谱特征以及由CO2倍增(2×CO2)引起的流场变化。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。