专门设计的

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。

According to search dog search data shows, 80 after parents is very happy with it the ground is sent in anticreep of appropriative of pregnant woman of the choose and buy on the net wash hair dew, complete set to protect skin to taste, the pregnant woman outfit of fashionable dress design, prevent what child excessive grandma uses to pat a back implement, the spoon drawing out ear that designs technically for the baby, suck drivel to use

根据搜狗搜索数据显示，80后父母乐此不疲地在网上选购孕妇专用的防脱发洗发露、全套护肤品、时装款式的孕妇装、防小孩溢奶用的拍背器、专门为婴儿设计的掏耳勺、吸鼻涕用的吸鼻器、学饮水用的学饮杯

GRE里面谈到17世纪中国园林:they were designed expressly to evoke the agreeable melancholy resulting from a sense of the transitoriness of natural beauty and human glory.

它们被专门设计来激发出一个令人愉快的忧伤情绪，这种情绪是由一种大自然的美和人类的光辉转眼即逝的感觉导致的。

The course canters around real situations that can and will arise in business dealings. Each session also addresses key cultural issues, which may have an impact on effective communication.

有效沟通是一门专门为公司和个人设计的实用易掌握的课程，课程教授了在不同的社交和工作场合所需要的必要的技能。

These powerful cushion tire trucks are manufactured for productivity; they provide significant lift capacities in a remarkably compact space and are specifically designed for applications with limited maneuvering space plus significant heavy lift requirements.

这些功能强大的缓冲卡车轮胎制造的生产力，他们提供了非常紧凑的空间显着提高能力，是专门为有限的回旋空间，另加重大重型运输机要求的应用而设计的。

Our special and rock drill steel company total investment of 500 million s , it ' s customized produce the rock drill steel for our products, we can produce almost all kinds of rock drill steel, in the production process, H22 Rod have the largest production output , it ' s using the material of 40SiMnCrNiMo （ Silicon, Manganese, Chromium, Nickel, Molybdenum ）, and it ' s performance are better than the rod use the material of 95CrMo and 55SiMnMo.

我们的特钢公司总投资额5个亿，是专门为钎具钢而设计的，几乎能生产所有钎具钢，在生产过程中，H22钎杆的生产量最大，采用的是40SiMnCrNiMo这种材料，性能比95CrMo和55SiMnMo都要好一些，因质量稳定，供货及时，价格合理，我们公司很快成为中国最大的H22钎杆供应商之一。

As you can now see, although pulsejet engines are intrinsically very simple in design and construction, to build one to a reasonable standard of quality and consistency takes many different steps, the right equipment, plus a number of specially built jigs and tools.

正如你现在可以看到，虽然pulsejet发动机在本质上是非常简单的设计和建设，建立一个合理的质量标准和一致性，以多种不同的步骤，合适的设备，加上专门修建的夹具和工具。

The 20-foot(6-meter)-long treadmill was designed specifically for Maggie, a 23-year-old female African elephant that has become the subject of a national debate over the proper care for captive pachyderms .

这台长20英尺（6米）的跑步机是专门为动物园中一头名叫麦吉的23岁雌性非洲象设计的。最近，全美都在讨论如何正确对待豢养在动物园里的大象，而被讨论的主角正是麦吉。

He'd sit at a desk the school maintenance staff designed for him, one that has lasted at the school ever since, always going to a tall kid who always knows it first belonged to Gasol.

他坐的课桌是学校专门为他设计的，那个课桌一直沿用至今，总是为那些很高的孩子准备的，并且孩子们都知道这个课桌的第一次是属于加索尔的。

Based on the results simulated by PRECIS (Providing Regional Climates for Impacts Studies), which is developed in the Hadley Centre for Climate Prediction and Research, changes of surface air temperature and precipitation under SRES B2 scenario in South China during 2071~2100 are analyzed. It is shown that, compared to baseline (1961~1990), surface air temperature in 2071~2100 would increase by 2~4℃, precipitation in summer would increase in the north part to 22°N, while the precipitation in winter would decrease in the whole areas of South China. The climate trend of the surface air temperature would be positive, however the climate trend of the precipitation would be negative, the occurrence frequency of extremely high temperature events and extremely heavy precipitation events would increase.

利用英国Hadley气候预测和研究中心的区域气候模式系统PRECIS，模拟分析基于政府间气候变化专门委员会 2000年发布的《排放情景特别报告》中设计的B2情景下华南区域2071~2100年的温度和降水量的可能变化，结果显示：2071~2100年均地面温度相对于气候基准时段（1961~1990年）上升约2~4℃；华南区域未来夏季降水量在22°N以北区域较气候基准时段增加，而以南区域减少；冬季降水则表现为华南区域较气候基准时段减少。2071~2100年华南区域的温度气候趋势系数为正值，年均降水气候趋势系数为负值。2071~2100年的高温事件和强降水事件的发生频率均比气候基准时段明显增加。

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。