查询词典 normal to the surface

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。

To correct this problem of shear test, we improved the equipment of lab large-scale shear test and developed an especially new one which overcome the disadvantages of normal equipment, make the result more accuracy and can do more analyze about the shear surface, dilatability of the mixture only through shear test.

本研究对室内大型直剪试验进行了改进，研发了新型的土石混合料室内大型直剪试验系统，克服了常规直剪仪存在的主要问题，还可以进行剪胀率、剪切面起伏特征、剪切面分形等研究，使得试验结果更精确、可靠，试验分析更完善。

Based on the continuity equation of groundwater and the normal velocity formula of free surface, taking element e as a subdomain R in the seepage flow domain R, according to variation principle, the finite element equation of seepage field can be obtained.

由地下水的连续方程和自由面的法向流速公式，把单元e作为渗流求解区域R上的一个子域ΔR，根据变分原理，得到岩土体渗流场有限元方程。

Loxodrome normal circular-arc spiral bevel gear transmission is a typical engineering application based on the principle of Betrand conjugate surface. It is likely to be the hi-tech prototype for the middle or large spiral bevel gear.

斜航式法向圆弧螺旋锥齿轮传动是贝特朗曲面原理指导下的一类典型工程实现，可望为中大型锥齿轮传动提供一种新技术原型。

Chapter 2: The chapter concentrates on the powerful instrument in studying the carrier transport properties—thermopower.. Starting with the base theory, the chapter discussed the thermoelectricity phenomenon in metal and semiconductor in detail, including the useful Mott formula, phonon drag effect (normal process and Umklapp process), abnormal thermopower in transition metal, two-band model, magneton scattering, and so on. To resolve the abnormal thermopower in low temperature, some theoretical models, such as the distortion of Fermi surface, resonant scattering, spin-bag model, were argued. Each of them has its limition.

第二章：对热电势这一研究物质载流子输运性质的手段进行了综述，从热电势的原理和基础理论研究开始，针对金属和半导体的热电势现象进行了详细讨论，包括研究工作中常用的Mott公式、声子曳引的正常过程和Umklapp过程、过渡金属异常的热电势现象、双带模型及磁子散射机制等等，对于低温下的异常散射机制讨论了声子曳引、费米面畸变、共振散射机制、自旋口袋模型等若干种理论模型及其局限性。

Divergence Theorem: is a vector theorem that allows a surface integral of the normal component of the vector to be transfomed into a volume integral of the divergence of a vector, or vice versa.

散度定理：将矢量表面积分转换为体积积分的散度形式。

The techniques for obtaining initial tracing points and tracing intersection branches are the most important issues in surface intersection algorithm. This paper reviews the plane vector field method which is exploited to get initial tracing points,and gives the relation between normal curvature and tracing direction.

平面向量场与曲率分析在曲面求交中的应用宁涛，马德昌，王亚平，唐荣锡（北京航空航天大学制造工程系北京100083）摘要在曲面求交算法中，初始跟踪点的确定和交线分支的跟踪是最关键的两个问题。

In addition, make note that maintaining the net clean, clear 10 adherent dirt, debris or oil pollution, but also always check silicone rubber roller surface is not affect the normal production of scratch and Dent, abnomity high., and so as not to affect the Peel strength composite products.

此外，还要注意保持各工装的清洁十净，及时清除粘附在表面上的灰尘、杂物或油污，还要经常检查硅橡胶压辊表面有无影响正常生产的划道、凹坑、碰伤等异常现象，以免影响复合产品的剥离强度。

The first stage is screen experiment. A 24-1 Fractional Factorial Design and resolution IV experiment is used to find out which main effect and interaction effect have obvious influence on the precision positioning of feeding table by these four factors. The Minitab program including Half Normal Plot, Pareto Chart, and ANOVA is applied to diagnose obvious effects. The second stage is optimization experiment. The fitness of regression model is obtained by using CCD of RSM with statistical hypothesis testing, regression analysis, lack-of-fit testing, and residual analysis. The optimum values can be found out by using response surface plot and contour plot.

在第一阶段为筛选实验采用24-1部分因子实验，解析度为IV，求出这4个因子主效应及交互作用哪些会对进给平台定位精度有显著的影响，在分析方面使用统计软体Minitab做初步分析，应用了半常态机率图、柏拉图与变异数分析来判断出显著因子与交互效应显著，第二阶段优化实验采用反应曲面法的中央合成设计，搭配统计检定、回归分析、缺适性检定(Lack-of-Fit)、残差分析来取决回归模式之合适性，最后根据反应曲面图及等高线图求出最佳值做验证实验。

E. , when they run under low temperature in winter, the formation of frost on airside heat exchanger surface has become a common problem, which leads to degradation of heating capacity and has effects on its normal running.

尽管空气源热泵冷热水机组作为中央空调冷热源有很多优点，但是，目前空气源热泵冷热水机组在应用中仍存在一些问题。

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％。