查询词典 noise wave

At the same time, combining with the actual condition of delivery pipeline of our country and some prevalent leak detection and location methods, this paper raised a method, which is based on wavelet analysis and negative- pressure-wave to detect and locate the leakage. Jobs in the paper are as follows:As affected by gas density, pressure, specific heat and pipe material, the velocity of negative-pressure-wave improved depending on the energy conservation. At one time, taking the affection of velocity of gas flow, the location formula was modified in some degree.When locating the leaks with location formula, the iterative approach algorithm was adopted as a new method to increase the location accuracy level of system.Multi-scale decomposition and reconstruction of wavelet transform is utilized to filter the noise of negative-pressure-wave, which was brought by leakage. With the capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the break point of pressure signal. The work improved the accuracy of At in location formula, accordingly improved the location accuracy.Wavelet is a suitable tool for signal analysis. The distinct character is that the mother-wavelet is of optional. That means choosing different mother-wavelet will get different analysis result. So we studied how to choose mother-wavelet and its scale for signal singularity detection. The method is to choose a wavelet by regularities of the wavelet and the signal.Finally, a plan, which bases on SCADA system for inspection and detection of natural gas leakage, is proposed in the article.

其中，主要进行了以下几方面的工作：针对泄漏产生的负压波在管道中的传播速度受媒介的密度、压力、比热及材质等因素的影响，而非声波在空气中传播的速度，本文利用能量守恒原理，对其进行了修正；考虑到管内气体流速对压力波速的影响，对原始的负压波定位公式进行了一定程度的改进，并在利用定位公式进行泄漏点定位时采用逐步迭代逼近算法，提高了系统的定位精度；利用小波变换的多分辨率分解和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行了降噪处理；并利用小波变换技术对信号奇异点的快速、准确的识别能力，对经上述消噪后的负压波信号进行了奇异点捕捉，精确捕捉的结果提高了定位公式中上下游站点采集到的负压波奇异点的时间差△t的精度，从而进一步提高了定位的精度；考虑到小波变换是一种基波可变的信号分析工具，也就是说，不同的小波基波对信号分析的结果将有很大差别，这势必影响最终的处理结果，因此，我们又对比分析了本课题中小波基及尺度的选择问题，依据规则性系数相似性原理对母小波的选择进行了探索性研究；最后，还提出了基于SCADA的泄漏检测与定位系统的软件开发构想及系统的嵌入方案。

According to singular entropy and Percent of contribution to total energy, the de-noising rank is obtained and the signal is reconstructed. The thesis compares reconstruct wave form of different reconstruct rank and the error of original signal and reconstruct signal is contrasted.According to voltage flicker measurement, voltage flicker detection method based on Mathe Matical filtering and Teager Energy Operator is proposed. The multiple MM filter filters out pulse noise and white noise contained in fliker signal, then the filtered signal is tracked accurately and quikly via TEO.

提出了基于数学形态滤波和TEO能量算子的电压闪变快速测量方法，含噪电压闪变信号经过多结构元素复合数学形态滤波后，采用TEO能量算子计算跟踪电压闪变信号的包络，得到的包络信号用Pisarenco谱分析方法获得闪变调制信号的幅值频率等参数，对不同情况下的电压闪变信号进行了仿真验证。

This burst waveform has benefits compared to a continuous wave emission in that the laser peak power can be very high for measuring long distances, yet the average power can be kept low for eye safety. And more, the pre-amplified optical receiver possessing temperature compensation and feedback resistance noise compensation is designed which is based on the noise spectrum density theory of silicon avalanche-photodiode.

同时根据硅雪崩光电二极管噪声谱密度理论，设计了具有温度补偿和反馈电阻噪声补偿的激光测距仪前放接收模块，详细分析了背景光，反向高压和反馈电阻对于Si-APD接收性能的影响。

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。

The algorithm of new strain wave that will put forward through example and Lee filter wave, broad sense is various Xiang Jiaquan all is worth configuration filter wave and with all possible means the effect that Xiang Jiaquan all is worth configuration filter wave to undertake inhibition spot of be concerned with makes clear as a result quite, this algorithm restrains the noise in image effectively not only, and the geometrical structure feature that better land maintains image.

通过实例将提出的新滤波算法和Lee滤波、广义多方向加权均值形态滤波和多方向加权均值形态滤波进行抑制相干斑的效果比较结果表明，该算法不仅可以有效地抑制图像中的噪声，而且较好地保持图像的几何结构特征。

Active noise control is achieved by introducing a canceling "anti-noise"wave of equal amplitude and opposite phase using a secondary source.

主动消声是利用声波之间的相消性干涉原理，使声场局部区域声能相互抵消，从而达到降低噪声的目的。

The strange noise caused by vibration detecting module. The system can save and redisplay various engine strange noise wave, which can provide analysis basis for failure diagnosis, and users can judge some failure by compare these waves with normal wave.

振动异响测试模块：通过对发动机各种异响波形的存贮、重显，并与标准异响波形对比后，可判断出多种常见异响故障，为故障诊断提供分析依据。

For frequency information fluid identification technology:the basic theory of fluid identification based on frequency information has been introduced,for inner and external factor affecting frequency,some steps have been proposed to attain reserved amplitude and frequency analysis data with high resolution,high S/N ratio;through the comparison of time-frequency analysis method, the high accuracy time-frequency analysis method has been selected to extract time-frequency attributes;the analysis method flow of common single frequency fluid identification has been proposed,according to the data of full frequency band,several anomaly zone modes of common single frequency attribute have segregated; incorporating converted wave and compression wave,fluid identification method based on PS wave combined time-frequency analysis has been proposed;the AVO property of various fluid type in frequency domain has been studied;the generalized fourier analysis method,Proni absorption filter has been introduced,and researched for anti-noise and for the seismic processing interpretation flow.The above technology have been applied to fluid identification of organic reef in WBT area in the east of Sichuan and fluid identification of clastic rock in GUANGAN area in the middle of Sichuan,the results show that the above methods are effective.

基于频率信息的流体识别技术方面：介绍了利用频率信息流体识别的基本理论，针对影响频率的内、外在因素，提出一些针对措施，以获得高分辨率、高信噪比的保幅、保频分析数据；通过时频分析方法的比较，选取高精度的时频分析方法提取时频属性；提出共单频属性进行流体识别的分析方法流程，结合全频带数据，分出几种共单频属性异常带模式；联合转换波资料和纵波资料，提出基于纵横波联合时频分析进行流体识别方法；研究了频率域内不同流体类型AVO现象；引进一种广义傅立叶分析方法：Proni吸收滤波，研究其抗噪性以及进行地震处理解释的流程；将这些技术应用川东北五百梯区块进行生物礁储层流体的识别和川中广安陆相碎屑岩的流体识别，取得较好的效果。

Under certain ratio of signal-to-noise and through the computer simulations and calculations, the performances in Mbius digital base band communication system of five often used modem function set, those are the even and odd symmetrical triangle wave, even and odd symmetrical square wave and saw-tooth wave and their inverse transforms, are simulated 10000 times, and the fluctuation ranges of the error rate P(subscript b are observed.

在一定信噪比的前提下，通过计算机仿真和编程计算，对Mbius数字基带通信系统中偶对称三角波、奇对称三角波、偶对称方波、奇对称方波和锯齿波这5种常用的调制解调函数族及其逆变换进行仿真1万次，观察错误概率P

The wave-front detection technique can amplify the variations of the wave-front of the debris flow. The debris flow becomes easy to discriminate. Based on the clean images processing, the detection ratio of the multiple filtering technique can increases from 56.36% to 95.27%. The noise removal technique can effective remove the pepper-and-salt noise and Gaussian noise. The clean images will reduce the false alarm rate for detection of remaining ratio technique.

土石流波前判识」使用前处理影像，可有效的将土石流波前扰动强度放大，较易正确判识出土石流波前；「多重滤波判识」经影像前处理后，可降低因环境带来的不当讯息，结果发现，其判识率由56.36%大幅提升至95.27%；「溪床特定物残留率」判识时，易将杂讯视为特定物，滤除杂讯可有效降低误判之机率。

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。