查询词典 noise

The results show that K-L transformation is an effective means to attenuate noise and improve signal noise ratio, and the effect of inhibition of the noise with K-L transformation is associated with the number of characteristic value.

结果表明，K-L变换可压制噪声提高信噪比，去噪的效果与所选取的特征值的个数有关。

The author ever saw with one's own eyes witnesses a child of 2 years old of toddle, the noise as a result of a shoe implement bad already, she to make another shoe gives out noise, when walking exert all one's strength the chela palm of a foot to walk downward, after that calcaneal criterion basically not touchdown, generation giving a person walks one kind " one foot is deep, one base is low " impression, fortunately the author discovers in time, reminded the parent to dismantle noise plant, the pose that the child walks just transforms somewhat.

笔者曾亲眼目睹一名2岁蹒跚学步的孩子，由于一只鞋子的响声器已坏，她为了使另一只鞋子发出响声，走路时便将一只脚的前脚掌使劲往下踩，而后脚跟则基本上不着地，给人产生一种走路"一脚深，一脚浅"的印象，幸亏笔者及时发现，提醒家长拆除了响声装置，孩子走路的姿势才有所转变。

Generally, the cross flow fan operating noise totally about 55 dB, but in the midnight when prominent frequency noise has become extremely annoying. This research attempted to different axial configurative tongue designed to improve penetrating single frequency noise of cross-flow fan.

一般而言，横流扇的运转噪音约55dB左右并不算大，但是在夜深人静时某些特别突出的单频噪音却显得极度恼人，因此本研究尝试以不同之轴向舌端构形设计来改善横流扇之尖锐单频噪音；并将录制之声音以音质参数分析，找出较佳的舌端与叶轮扭转角度搭配。

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。

Then, main noise sources of the system are modeled by introducing 3-D noise model. At last, the assessment method of the degression of image enhancement algorithm on image noise is proposed.

仿真结果表明：经微光系统传递后，图像中的高频信息变模糊，加入噪声后，信噪比降低；而经过5帧平均算法后的图像质量明显改善，对比度增加。

For example, DPCA has desolately studied in their car body model for noise reducing effect; outer equipment and other connective parts are considered enough for noise reduction, for example, taking test on model of rear-view glass which may produce noise.

例如车身造型充分考虑降低扰流噪声，在外部设备和连接部分都精心研究，比如后视镜这个可能产生噪音的部件，就在模型上进行扰流测试。

For example, DPCA has desolately studied in their carbody model for noise reducing effect; outer equipment and other connective parts are considered enough for noise reduction, for example, taking test on model of rear-view glass which may produce noise.

例如车身造型充分考虑降低扰流噪声，在外部设备和连接部分都精心研究，比如后视镜这个可能产生噪音的部件，就在模型上进行扰流测试。

Based on the simple global noise source, take the noise which is cared by people into account. Get the sound pressure level after processing the noise sources sound pressure. Educe the allowable value of the upper limit, through linking to the sound pressure level which is permitted. Taking the value into the reliability modals established before, found the diplex integral mathematics modals that is restricted.

考虑约束因素的影响，引入人们所关心的噪声，以结构简单的球形声源为基础，在对声源声压做了相对处理后，得到其声压级，结合许用声压级指标，求得许用频率上限值，将该值代入已建立的防共振模糊可靠度模型，建立有约束防共振模糊可靠度计算的双重积分数学模型。

Low noise amplifier can amplify own noise, but its resistance and electric capacity noise should be low.

低噪声放大器除了放大自身噪声外，还需要电阻、电容的噪声也很低。

The noise performance of the electrometer is analyzed in detail and conclude that the input current noise is main factor on noise of the electrometer.

对静电计放大器的噪声性能做了细致的分析，确定了输入电流噪声为放大器噪声的决定因素。

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。