变干

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。

The researchers said the skin dries out and retracts after death, giving the appearance of longer hair or nails.

研究者说，死后皮肤会变干并且收缩，所以显得头发和指甲更长了。

This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved.

重复这个浸泡，变干的过程直至获得足够的厚度。

Preventive Maintenance on Waste gas abatements (wet scrubber, incineration scrubbers, dry scrubbers).

废气处理设备的预防性维护（潮湿的，炭化的，变干的洗刷器）。

It is important to let the soil dry out quite a bit between waterings: it should not still be wet when you water again.

但重要的是必须让土壤变干一段之间waterings ：它不应该仍是湿当你再次水。

It is important to let the soil dry out quite a bit between waterings: it should not still be wet when you water again.

但重要的是必须让土壤变干一段之间waterings ：它不应该仍是湿当您再次水。

The cattle,their winter coats still only gone in patch es（补丁,补片,补块,形容牛身上脱毛尚未完全脱净的斑驳形象）,began to low in the meadows.crook-legged lambs began frisk ing about their bleat ing mothers,just losing their wool; nimble-footed children began rushing about the quickly drying paths marked with the imprints of bare feet,the merry voices of women bleach ing linen began chattering by the ponds,and the axes of the peasants getting their wooden plows and harrow s ready began ringing out in the yards.

牛群身上的毛尚未完全脱落，就已经开始在草地上哞哞叫；弯腿小羔羊开始在他们咩咩叫着的母亲们身旁活蹦乱跳又开始脱了毛；机灵的孩子们在印着脚印及迅速变干的路面上来回奔跑着；池塘边响起了洗衣农妇们愉快的闲谈声。院子里听得见农夫们制造木犁和耙的斧头声。

You should keep a spritz bottle full of water at hand, just in case your hair begins to dry out.

你应该保持spritz瓶子装满水的手，以防万一你的头发开始变干。

We dry herbs by stringing them from rafters in the barn.

我们把草药挂在谷仓的椽上使之变干。

P in Shule River Alluvial Fan Oasis in Gansu subsidized by CNSF. Through field geological and environmental observations and sampling, quartz OSL dating, organic carbon ~(14)C dating, as well as analysis of TOC,grain size and Pollen assemblage of the samples from ten sediment profiles in front fine grain sediment zone of the Shule River Fan, the results obtained as follows:(1)The vegetation evolution history on Shule River Alluvial Fan and circumjacent since about 13 ka B.P. could be divided into 6 phases: about 12.1-13.1ka, a sparse coniferous and broadleaf trees - shrub grassland, cold and wet climate; 9.2-12.1ka, shrub grassland, temperature rising but precipitation and humidity getting down; 5.8-9.2ka, sparse forest with the most flourish shrub grassland under the optimal climate; 4.3-5.8ka, coniferous and broadleaf mixed forests -shrub grassland, temperature rising slightly and getting dry; 4.3-2.8ka, grass vegetation and climate became more dry; 2.8-2.3ka, coniferous forests -shrub grassland, precipitation and temperature getting down, but a higher relative humidity.

本文依托于&甘肃疏勒河冲积扇5万年来古天气环境与古水文演化&项目，以疏勒河冲积扇为研究对象，通过对疏勒河冲积扇扇缘细土带全新世古天气和古水文演变进行了20余个剖面的观测和取样、石英OSL和~(14)C测年、粒度组成和TOC分析以及孢粉鉴定，获得了以下成果和熟悉：(1)距今约13ka年来冲积扇和周边植被演化经历了6个阶段：约13.1～12.1ka，以针叶林为主的针阔混交林～灌丛草原，天气冷湿；12.1～9.2ka，灌丛草原，气温升高，降水量较低；9.2～5.8ka，疏林灌木草原，植被茂盛，温度和降水最佳；5.8～4.3ka，以针叶树为主的针阔混交林～灌丛草原，气温较高，降水减少；4.3～2.8ka，草原植被，天气变干；2.8～2.3ka，针叶林～灌木草原，降水减少，温度降低，相对湿度有所增加。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。