查询词典 surface noise

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。

Based on a series of signal process and noise source identification techniques, especially the major noise source identification methods, such as expurgation method, sound intensity analysis, spectrum analysis vibro-acoustic correlation analysis and so on, the pass-by noise control of SC7080A and SC6360B are studied in detail. By the roadway and dais experiments, the major noise and radiating parts are identified and some economical controlling methods are made. For the SC7080A, to control the emissing noise from the intake and shell vibration of air cleaner, a intake muffler is installed between the air cleaner and intake valve. Based on the theory of Helmholtz resonator, One three-parallel-connected resonant silencer is designed and trial-manufactured. For the SC6360B, the attenuation performance of exhaust muffler in high frequency region is improved. To reduce the vibration noise of shell part, the structure of oil sump tank, exhaust manifold shield and exhaust manifold shield are analyzed and improved. At the same time, some measures, such as sound absorption, sound insulation, are taken to reduce the noise of engine surface emissivity and a sound shield is designed.

本文首先综述了目前国内外汽车加速噪声控制的现状、主要方法和技术措施，在此基础上，结合SC7080A和SC6350B汽车的车外加速噪声水平及现状，综合运用分别运行法、声强法、频谱分析法、声振相干函数法等现代噪声源识别方法，对SC7080A和SC6360B汽车进行了准确详细的车外加速噪声源识别并提出了经济可行的控制方案，针对SC7080A，主要在空气滤清器和进气阀门之间的进气管道上加装进气消声器，抑制空气滤清器壳体表面和进气口两处的噪声辐射，根据Helmholtz共振腔原理设计了三腔并联旁支型共振消声器，并进行了工程化设计和试制；针对SC6360B，主要改善了排气消声器在高频段的消声性能，对罩壳类零件进行了结构改进，降低了其表面噪声的辐射，并对发动机舱进行了吸声、隔声处理，设计了发动机隔声罩。

The noise radiation of the gear case is estimated by a special method, in which, the impact of the vibration phase of each partial surface and the time of the sound wave from the surface to the position at which the noise is calculated are taken into account.

考虑到噪声辐射面各部分的振动相位和声波从它们传播到计算噪声点的时间互有区别，使用了在复数域迭加声波的辐射噪声计算方法。用这种方法计算了齿轮箱的辐射噪声分布。与已有的理论和试验结果进行了对比。

This paper reviewed the advances of noise barrier structure in China, and illustrated the development of multiple-edged, T-shaped and Y-shaped top structures used for noise barriers abroad. The development of some new top structures, such as soft surface, quadratic residue diffusers surface of noise barriers was also introduced.

作者对国内声屏障结构形式的现状进行了分析，介绍了国外常见的多重边、T型、Y型等顶部结构的发展情况，同时介绍了声学软表面、平方余数序列表面等新型顶部结构的发展状况。

The same goes fo-r another rather extreme example, Enrico Caruso's earliest reco-rdings from 1902 (Naxos Histo-rical). Yes, the surface noise of the shellacs is presented in just as much detail (if not mo-re) as Caruso's voice, but once you listen through that you can discover a dimensionality in the reco-rding that wasn't there befo-re.

同样另外一个例子是Enrico Caruso's 在1902年的录音(Naxos Histo-rical)，胶唱片与唱头的摩擦声伴随着 Caruso 的歌声，但当你一听到时，却感觉到音场的宽广是以前没有过的。

Ceramic bearings can produce oxidation-ho, silicon carbide, silicon nitride and so on, diameter from 3mm-50mm, precision Machinable P0, P6, P5 level; its performance characteristics are: high temperature, oil-free self-lubricating, acid, alkali and salt corrosion , wear resistance, low noise, insulating diamagnetic, since high-speed operation; metal nano-ceramic bearing its production process for a new generation of high content of nano-particles in the heat and pressure infiltration of metal surface is activated to fill the cracks and pits the metal so that 3-5 micron metal surface is more smooth solid surface, greatly reduce the friction, improve Chennai base metals, and greatly increased the life span of bearings, and its characteristics are: long life (as an ordinary stainless steel bearings 2 -- 10-fold), low noise (as an ordinary stainless steel bearings, 70%), wear-resisting, acid, alkali, salt corrosion, high temperature, load large; ceramic bearing and metal nano-ceramic bearing design and development to meet the needs of the market for high-speed, low - noise, high load, the demand for corrosion-resistant; Machinery Production Department to produce aircraft rod end joint bearing, linear guide bearings, the fuel tank of earrings, plastic bearing, non-standard side bearing components, glass door hardware, such as high-precision control products; and provide CNC machining.

陶瓷轴承可生产氧化镐、碳化硅、氮化硅等，内径从3mm-50mm，精度可加工P0、P6、P5级；其性能特点为：耐高温、无油自润滑、耐酸、碱、盐腐蚀、耐磨、低噪音、绝缘抗磁、起高速运转；金属纳米陶瓷轴承其生产工艺为新一代的高含量纳米级微粒在热和压力的作用下被激活渗入金属表面，填补金属缝隙和凹坑，使金属表面3-5微米表面更光滑坚固，大大降低其摩擦力，提高金属的奈酸碱性，并大大提高了轴承的寿命，其特性为：长寿命（为普通不锈钢轴承的2-10倍）、低噪音（为普通不锈钢轴承的70%）、耐磨、耐酸、碱、盐腐蚀、耐高温、负载大；陶瓷轴承与金属纳米陶瓷轴承的设计开发以满足市场对高转速、低噪音、高负载、耐腐蚀的需求；机械生产部以生产机杆端关节轴承、直线导轨轴承、油缸耳环、塑料轴承、非标端轴承零部件、玻璃门控五金等高精度产品；并对外提供数控加工。

Apply basic principle of control mechanical noise to measures had been put forward to reduce vibration and noise, and idle of the wood surface planer was remarkable reduced after the measures of reducible vibration and noise were used.

运用机械噪声控制的基本原理提出了减振降噪措施，试验证明，采用这些减振降噪措施后，木工平刨床的空转噪声有了显著下降。

In this article, the direction determining of low-noise targets and measurement of underwater noise level in the condition of surface noise is discussed.

文章摘要：文章对存在海洋表面噪声时的低噪声目标的方向测定问题和水下噪声级测定问题进行了讨论。

Some radio interference and pitch discrepancies, together with the inevitable surface noise, remain apparent despite considerable technical work.

虽然经过了很多技术处理，但是一些电波乾扰和音调差异以及无法摆脱的盘片表面噪音仍然很明显。

Surface noise?

表面噪声

The labia have now been sutured together almost completely.The drains and the Foley catheter come out at the top.

此刻阴唇已经几乎完全的缝在一起了，排除多余淤血体液的管子和Foley导管从顶端冒出来。

To get the business done, I suggest we split the difference in price.

为了做成这笔生意，我建议我们在价格上大家各让一半。