噪

Furthermore, it avoids solving nonlinear partial differential equation numerically comparing with the energy minimization denoising model of bounded variation, and so it never leads to local minimum in general.

与基于压缩比和奇异值分解的降噪方法相比，由于该算法避免了图像压缩比函数及其拐点的计算，因此具有快速去噪和简单可行的优点。

HKBWS China Programme is going to produce a poster which will be used by bird watching societies in China to promote the 16 Chinese endemic bird species. These bird species include White-necklaced Partridge, Cabot's Tragopan, Grey-hooded Parrotbill, Rusty-throated Parrotbill, Chinese Monal, Sichuan Jay, White-speckled Laughingthrush, Omei Shan Liocichla, Brown Eared-pheasant, Snowy-cheeked Laughingthrush, Gold-fronted Fulvetta, Elliot's Pheasant, Reeve's Pheasant, Hainan Patridge, Hainan Leaf-warber and Taiwan Bulbul.

香港观鸟会中国项目将制作一张让国内鸟会使用、介绍中国特有种的海报，用来向国内市民宣传保育这些特别的鸟种，海报中包含16种中国特有鸟类，包括白眉山鹧鸪，黄腹角雉，暗色鸦雀，灰冠鸦雀，绿尾虹雉，黑头噪鸦，白点鶥，灰胸薮鶥，褐马鸡，黑额山噪鶥，金额雀鶥，白颈长尾雉，白冠长尾雉，海南山鹧鸪，海南柳莺，台湾鹎。

This method is proved to be effective by a simulation example and comparison with recent de-noise using wavelet theory.

通过仿真研究和与目前小波去噪方法进行对比，证明了该方法去噪的有效性。

It can be seen from the theoretical analysis that the signal to noise ratio in the output of the canceler will improve when the signal to noise ratio in the reference input drops.

通过理论分析可以看出，随着本艇自噪声有源抵消器参考输入端信噪比的降低，系统输出端信噪比升高。

This paper combines with pipeline delivery of our countrys actual conditions and other methods of detection and location. To the leakage characteristic of the fault to the long-distance natural gas pipeline, a method is raised, which is on the basis of wavelet and negative-pressure-wave to detect the leakage and locate. Jobs in this paper are as follows:Multi-resolution decomposition and reconstruction of wavelet transform is utilized to filter the noises, which the leakage brings the noises of negative-pressure-wave. The research is worked in the wavelet and wavelet packet filter. The wavelet transform have a fast and accurate recognition capability to signal singularity. This paper chooses wavelet technology to catch the break point of pressure signal.

本文结合我国管道输送的实际情况和目前现有的各种泄漏检测与定位方法，针对天然气长输管线泄漏故障的特点，提出了基于小波分析和负压波相结合的方法检测泄漏并定位，其中主要进行了以下几个方面的工作：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降噪处理，并对小波及小波包优化的降噪效果进行对比性研究；利用小波变换技术对信号奇异点的快速、准确的识别能力，捕捉负压波信号的突变点，从而判断是否有泄漏发生。

Because the temperature along the pipeline is not a constant, it changes the velocity of the negative-pressure-wave; the Romberg algorithm of numeric integral and the searching for algorithm are emloyed to locate the leakage.Multi-scale decomposition and reconstruction of wavelet transform is applied 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 Δt in location formula, and the location accuracy is improved.

利用小波变换的多分辨分析和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行了消噪处理；并利用小波变换技术对信号奇异点快速、准确的识别能力，对经过消噪处理后的负压波信号进行了奇异点捕捉，准确确定了定位公式中上、下游站点采集到的负压波奇异点的时间差△t，从而提高了定位的精度。

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。

For the multi-layer absorber composed of perforated plate, composed of perforated plate and cavity, composed of perforated plate, porous absorption material and cavity, the absorption coefficient is theoretically calculated.

论文回顾了主动消声、吸声降噪的发展历史与现状，阐述了主动吸声降噪有待解决的关键技术问题，提出了论文的主攻目标和研究内容。

This thesis has discussed the theory of measuring distance in ultrasonic, which include ultrasonic shaking transmit velocity, central frequency, angle of launch control, measure distance, dynamic measure and so on. According to character of wave shape output by circuit, this thesis has designed an efficient way to diminish noise that enables precision of the ultrasonic sensor to 0.2%.

论文详细论述了超声波测距的基本理论，包括超声波震动传播速度、中心频率、发射角控制、发射能量、检测距离、动态检测等；并根据电路输出波形特征设计了有效的降噪方法，使超声波传感器的精度达到了0.2%，然后对降噪后的信号进行了标定。

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。

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。