查询词典 be a model for others

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 text is based on the work that analyse the problem having emerged about large-scale economic affordable residential district of city at the moment, in instance of the patterns in Xi'an. Through investigating living circumstances and building present situation, there are lots of requirement for economic affordable housing in Xi'an. As large requirement for premise, the question about choosing location large-scale economic affordable residential district in city is researched. As time as, it should be refer to the problem which were founded in others cities, then summarize a correct choosing location model for the practical situation, it could determent the location of large-scale economic affordable residential district of Xi'an.

本文以分析现阶段城市大型经济适用居住区产生的问题为依据，立足西安地区，通过调查该地区居民的居住现状以及房地产开发状况，指出经济适用住房在西安地区具有广泛的需求市场，在这种巨大需求量存在的前提下，探讨大型经济适用居住区选址问题，结合现有其它城市大型经济适用居住区中发现的问题与不足，提出一套适合实际情况的选址模式，并且根据该模式分析了西安大型经济适用居住区选址的区位。

According to the energy conservation theory, BOM and CSIM4 were coupled. The BOM has no treatment on transmission solar radiation, which is of great importance when the model is adapted to Arctic Ocean. So the treatment was introduced to BOM. Through numerical test on different lead albedos, it was found that sea ice thickness is not so sensitive to lead albedo, which may be contribute to the lead occupies little ratio within multiyear sea ice pack. The reason of summer over-melt of arctic sea ice is the NCEP reanalysis downward solar radiation being larger than its reality. Then the arctic sea ice climate variability was simulated. Results showed that: simulated ice thickness change is in accord with the submarine investigated mean sea-ice draft changes. Simulated annually maximum ice thickness along the Eurasian continental oceans are closely related to the observed ones. The long-term mean simulated ice motion has the same features of the SSM/I derived ice motion. Sea ice extents in differential sub-regions have same trends comparing to the satellite passive-microwave data derived ones. Simulated ice concentration is closely related to the observed in the Arctic sub-regions. Sea ice flux through the Fram Strait involves ice concentration, motion and thickness. It is a composite criterion for sea ice model evaluation. The simulated ice area and volume export through the strait accord with the satellite derived or statistically reconstructed ones.(5) The simulated ice thickness climate variability and mean sea surface current of the coupled model were analyzed, results showed: the total ice volume in the Arctic Ocean has a significant decreasing trend. The volume variability is of a 10-year timescale oscillation, with two major periods of 12-13a and 18-20a. Mean ice thickness in the arctic sub-seas has different tendencies. It has an increasing trend in the Barents-Kara Sea and Baffin Bay-Labrador Sea, and decreasing in the others. The characteristic time scale of 7-10a wherein the river discharges leads the Fram Strait ice volume export is about the period that river water takes to be conveyed across the Arctic Ocean.(6) Using the simulated ice distribution in the Arctic Ocean and China precipitation, air temperature and SST in tropical key regions, the climate teleconnection were studied. Result showed: When the mean sea ice thickness is large in the central Arctic Ocean and Chukchi-Beaufort Sea , and small in the Barents-Kara Sea and Baffin Bay-Labrador Sea , the precipitation in South China, Tibetan Plateau, and the north part of Northeastern China are always smaller than normal, and v. v. When the mean ice thickness is small in CA, BC, East Siberian Sea and Greenland-Iceland-Norwegian Sea , and large in BL, The air temperature in north-eastern China, the southern of Tibetan Plateau, and Hainan Island, are always lower than normal, and v. v. In addition, when the sea ice is thick in BC and BL, the SST is larger in the middle and eastern Pacific Ocean, and is smaller in the tropical Southeastern Indian Ocean.

由于BOM没有考虑透射太阳辐射的物理过程，研究表明透射太阳辐射对北冰洋的能量收支起到重要作用，因此在BOM模式中引入了对透射太阳辐射的处理；通过对不同水道反照率的数值试验表明海冰厚度对水道反照率的敏感性不强，可能与海冰区水道面积占的比率很小有关；而模式模拟的北极海冰夏季&过度融化&主要源于NCEP再分析资料提供了偏大的太阳短波辐射；对北极海冰的气候变率进行了模拟研究，结果表明：模拟的海冰厚度变化与潜艇探测的海冰吃深度变化具有一致性；模拟和观测的亚欧大陆沿海的年内最大海冰厚度有很好的相关；模拟的海冰移速与长期平均的卫星反演的海冰移速具有相同的速度分布特征；模拟的各个海区海冰面积的变化趋势与卫星反演资料分析的结果基本一致；模拟与观测的主要海洋分区的海冰密集度具有很好的相关：弗瑞姆海峡的海冰体积和面积的输送涉及到海冰密集度、厚度和移动速度，是判断模式模拟能力的一个综合的指标，模式模拟的结果与卫星反演或重建的面积输送、体积输送具有很好的一致性；(5)分析了模拟的北极海冰厚度的气候变率及气候平均表层海流场，结果表明：北极海冰的总体积有显著减少的趋势，北极海冰总体积的变化具有10a际尺度振荡的特点，存在18-20a和12-13a两个主周期；北极海冰的平均厚度在各个海区的变化趋势不同，在巴伦支—喀拉海和巴芬湾—拉布拉多海地区海冰厚度有显著的增加趋势，而其它海区存在减少的趋势；通过对模拟的气候平均表层海流的分析表明，北极河流流量超前弗瑞姆海峡海冰流量7-10年的特征时间尺度与表层海流的气候分布存在着必然联系：(6)利用模拟结果以及中国降水、气温和热带关键区SST资料，讨论了北极各海区海冰平均厚度与中国降水、气温以及热带关键区SST的关系，结果表明：在北极中心海区和楚科奇—波弗特海海冰厚度偏大，在巴伦支—喀拉海以及巴芬湾—拉布拉多海海冰厚度偏小，则中国降水在华南地区、青藏高原和东北北部降水偏少，反之相反；在北极中心海区、东西伯利亚海、楚科奇—波弗特海以及格陵兰海海冰厚度偏小，在巴芬湾—拉布拉多海海冰厚度偏大，则在中国东北地区、高原南部地区和海南岛附近气温偏低，反之相反；另外，北极楚科奇—波弗特海和巴芬湾—拉布拉多海海冰厚度偏大时，在热带中东太平洋海温偏高，而在热带东南印度洋海温偏低。

At his instigation Louis built for him a monastery adjoining his own palace at Aix-la-Chapelle, which was intended to serve as a model according to which all others were to be reformed, and to bring about this end Benedict was invested with a general authority over all the monasteries of the empire.

在他的煽动路易斯为他建造的一个修道院毗邻自己的宫殿在阿亨，这是打算作为模型根据这些所有其他人进行改革，并带来笃为此投资进行了一般性权力的所有寺庙的帝国。

Some observers expect it to be refitted as a practice vessel and others think China could use it as a model for a future home-built carrier.

一些观察人士认为，这艘航母可能被改造为一艘试验舰，另一些人认为，中国可能将其用于未来建造国产航母的模型。

I will be a role model for others.

我要成为别人的榜样。

I will be a role model for others!

我会成为别人的榜样！

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。