查询词典 signal noise ratio

Since the glint noise is a low-frequency noise and its bandwidth is usually lower than that of flight control system, therefore low pass noise filtering is not practical for guidance command and noise are not distinguishable.

闪烁杂讯属低频杂讯，通常比飞控制系统频宽还要低，无法与导引命区分，所以能只用低通波器将其除。

In digitizing analogue signals, the digital signal is corrupted by the noise due to the inherent noise of the sampler and the quantizing noise.

在这两个过程中，由于采样器固有噪声和采样脉冲抖动噪声以及量化噪声等因素的影响，采用量化后的数字信号中含百噪声。

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。

AR model is applied to identify the noise source for enigne. Through the results of noise signal process, it shows that it is practical and credible to use AR model to study engine noise. Through the theoretical analysis, according to the specific engine structure, the SEA equation is formulized. The method of SEA sensitivity is brought forward on the basis of the sound power function.

从理论分析入手，结合具体的发动机产品结构，建立了结构噪声分析的统计能量方程，提出了基于声功率函数的统计能量灵敏度分析方法，把发动机的外在表现和内在因素直接联系起来，分析了系统主要参数对系统声功率的影响程度，得出了一些实用性的定性结论。

The signals during transformer impulse test are considered to be evolving in time, also is non-stationary signals, so we can design a software algorithm for noise reduction based on discrete Gabor transform, and the basic principle is: The Gabor coefficients of Effective signals during transformer impulse test is centralized in the time frequency range, and the peak-to-peak value is big, whereas the noise Gabor coefficient distribute in the entire time frequency range equally, the peak-to-peak value is small, we can realize the desired signal and the noise separated through frequency mask function.

考虑到冲击试验中的信号都是时变信号，也就是非平稳信号，因此设计了一种基于离散GABOR变换的软件滤波算法对冲击信号进行滤波，其滤波理论依据是：有效信号的Gabor系数在时频域分布比较集中，幅值比较大，噪声的Gabor系数均匀分布于整个时频域，幅值较小，通过构造时频掩模函数来实现有效信号与噪声的分离。

Through the processing method basing on wavelets, implementing the removing noise about section gauss noise to colure full TV signal, we resolve the theory and practice problems in the processing of weak signal detection.

通过基于小波分析的处理方法，实现对彩色全电视信号一段被高斯白噪声干扰的降噪，解决微弱信号检测过程中遇到的理论和实践问题。

Because one need to search H in the range of 110, 1 and calculate the autocorrelation function many times, the concise formula of autocorrelation function of discrete fractional Gaussian noise is used to improve the processing speed. Simulation results have shown that it can estimate H accurately and more effectively than conventional LMS based on autocorrelation ftinction for both pure fractal signal and noise-corrupted fractal signal.

接着我们研究了在白噪声背景下进行分形参数估计的相关函数法，针对其在计算中需反复使用自相关函数的特点，提出了一种改进的相关函数法，实验表明，改进的方法在精度上几乎没有损失，而大幅度地提高了计算效率。

At first, the characteristics of probability distribution and frequency spectrum of noise inside measuring signal of feedback elements are discussed. Statistic filter method is come up with for noise signal of being Gauss distribution. It is analyzed reason that statistic filter method is superior to arithmetic average filter method.

分析了反馈元件测量信号中噪声的概率分布特性和频谱特性，对呈正态分布的噪声信号提出了统计滤波法，分析了该滤波法优于算术平均滤波法的原因。

In the measure amplification circuit, direct-current or low frequency signal come from a common sensor , conveying in only rhyme fashion way after amplification, In typical situation, serviceable signal maximum amplitude probable only have a certain number or amount millivolt, but common mode noise suppression may be up to several volt, as a result it is significant to the factor of the amplification input drift and noise etc for total precision, the amplification in itself common mode restraints features is also equally binding problem.

在测量用的放大电路中，一般传感器送来的直流或低频信号，经放大后用单端方式传输，在典型情况下，有用信号的最大幅度可能仅有若干毫伏，而共模噪音可能高到几伏，故放大器输入漂移和噪声等因素对于总的精度至关重要，放大器本身的共模抑制特性也是同等重要的问题。

Most devices integrate the emission of each input point over a specified time interval before yielding a signal that is proportional to noise reduction, thus making image dissectors attractive in applications where high signal - to noise rations are required.

在所有的设备在规定时间间隔内把每个输入点综合在一起，然后产生一种与噪音降低成比例的信号，从而使图像分解器在信号／噪音定量需求高的应用中更具吸引力。

Putt your way through 36 fun-filled holes of minigolf on 3D designed courses with elevated greens, bunkers, bridges and water hazards, among other crazy obstacles.

您的推杆方式，通过36个有趣的填孔迷你的三维设计的课程，以提升绿党，掩体，桥梁和水的危害，除其他疯狂的障碍。

Some participles can be used either as attributes or as predicatives.

有些分词既可当定语用，也可当表语用。