不变

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。

Among the 65 types of disyllable groups ("IVB + IVA" are divided into two kinds, and are counted as two here), there are 41 types that only change the initial syllable and not the final one, 8 types that only change the final syllable and not the initial one, and 16 types that change both syllables.

在65种两字组（"阳入＋阴平"变调时分两类，这里按两种计）中，有41种只变前字不变后字，有8种只变后字不变前字，有16种前后字都变。

For a monotone twist map the well-known Birkhoff fixed point theoremsays that the circles with rational rotation number will break up whence a finitenumber of pairs of periodic points arise,half of which are elliptic and the othershyperbolic.Moreover,around each elliptic periodic point a few of new invariantcurves will appear and make a picture of phase space with a self-similar structure.Again one may ask is there a similar picture for higher dimensional Hamiltoniansystems?

对于单调扭转映射，著名的Birkhoff不动点定理指出，在通有情况下旋转数为有理数的不变曲线一般会破裂，在原来的不变曲线附近会产生有限多对周期点，其中一半是双曲的，一半是椭圆的，而在椭圆型周期点的周围又会产生一圈圈的不变曲线，使得椭圆周期点附近的动力学行为和整个相空间的动力学行为十分相象，换句话说，整个相空间具有无限嵌套的自相似结构，自然又产生了一个问题：对于自由度数目大于2的高维哈密顿系统，其相空间是否有类似的图象？

In the athletae, embonpoint, if carried to its utmost limit, isdangerous, for they cannot remain in the same state nor be stationary;and since, then, they can neither remain stationary nor improve, it

健壮者若变得过于肥胖则危险，因肥胖之躯不会固定不变；既不可能固定不变或有所改善，则只会每况愈下；为此应及时减肥，不可拖延，以便使身体恢复健康。

"Wisdom lies neither in fixity nor in change, but in the dialectic between the two."

费译：智慧不在不变，也不在恒变，而在不变和恒变之间的辩证之中。

The spectral curve vs invariant mass is becoming wider and the peak is shifted towards the high invariant mass region with the increase of temperature. However, in ultra high temperature or density envi- ronment, the peak is shifted towards lower region and the curve is changed narrower with the increase of temperature. In the invariant mass region M 憕.-?0.4 GeV?.6 Ge1~, the spectral function is enhanced very much. which contributes to the interpretation of dilepton enhancement results in relevant experi

结果显示高温高密强子物质环境对其有非常重要的影响：ρ谱函数在温度或密度不太高时谱函数曲线变宽，并且峰朝不变质量高的方向移动；在极端高温或高密情况下谱函数却变窄，并且峰朝不变质量低的方向移动，在不变质量M～0.4-0.6 GeV区间谱函数有比较明显的增强，这有助于解释双轻子产生的相关实验现象。

A new viewpoint that human nature and human existence should be dialectically united is expressed in this paper.

在对人性与人的本质的变与不变的关系上，人性与人的本质既有不变的一面，也有发展变化的一面，是变与不变的统一。

Bellows Gate Valves However, in large differential pressure operating conditions, evaporation pressure has eased, the evaporator load requirements of the fluid volume decreased, but the actual situation the contrary, in the suction superheat unchanged, due to evaporation pressure has eased, the evaporator outlet pressure be reduced accordingly, pressure changes above and below the diaphragm, causing the main valve opening increases for increased fluid; but in a small pressure operating conditions, evaporation pressure rise, evaporator load demand for fluid volume increased, but the reality is that in the suction gas superheat unchanged, due to evaporation pressure rise, a corresponding increase in the evaporator outlet pressure, pressure difference above and below the diaphragm smaller, so that the main valve opening decreased for the reduction of liquid volume; in variable load is all about.

但在大压差工况下，蒸发压力降低，蒸发器负荷需求的液量减少，但实际情况相反，在吸气过热度不变的情况下，由于蒸发压力降低，蒸发器出口压力相应降低，膜片上下的压差变大，使主阀开度增大，供液量增加；但在小压差工况下，蒸发压力上升，蒸发器负荷需求的液量增多，但实际情况是在吸气过热度不变的情况下，由于蒸发压力上升，蒸发器出口压力相应提高，膜片上下的压差变小，使主阀开度减小，供液量减少；在变负荷下亦如此。

However, in large differential pressure operating conditions, evaporation pressure has eased, the evaporator load requirements of the fluid volume decreased, but the actual situation the contrary, in the suction superheat unchanged, due to evaporation pressure has eased, the evaporator outlet pressure be reduced accordingly, pressure changes above and below the diaphragm, causing the main valve opening increases for increased fluid; but in a small pressure operating conditions, evaporation pressure rise, evaporator load demand for fluid volume increased, but the reality is that in the suction gas superheat unchanged, due to evaporation pressure rise, a corresponding increase in the evaporator outlet pressure, pressure difference above and below the diaphragm smaller, so that the main valve opening decreased for the reduction of liquid volume; in variable load is all about.

但在大压差工况下，蒸发压力降低，蒸发器负荷需求的液量减少，但实际情况相反，在吸气过热度不变的情况下，由于蒸发压力降低，蒸发器出口压力相应降低，膜片上下的压差变大，使主阀开度增大，供液量增加；但在小压差工况下，蒸发压力上升，蒸发器负荷需求的液量增多，但实际情况是在吸气过热度不变的情况下，由于蒸发压力上升，蒸发器出口压力相应提高，膜片上下的压差变小，使主阀开度减小，供液量减少；在变负荷下亦如此。因此热力膨胀阀在变工况下供液量的调节方面需进一步改进。

We promise that the quality is unchanged; service is unchanged; credibility is unchanged; empressement is unchanged!

我们可以坚定承诺的是：品质不变，服务不变，诚信不变，真诚不变！

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。