多尺度声表面波式小波变换处理器及小波反变换处理器的研究

发布时间：2018-04-17 18:43

本文选题：Mortlet + 小波变换处理器　；参考：《东华大学》2017年博士论文

【摘要】：小波变换是一个时间和频率的局部变换。小波分析在时域和频域同时具有良好的局部化性质,特别适用于非稳定信号的分析与处理。因此小波变换广泛应用于数学、信号分析、语音合成、图像处理、量子力学、电子对抗、计算机识别、数据压缩、地震勘探、大气与海洋分析、机械故障诊断等多领域。小波变换算法需要大量的数学运算和复杂的编程,因此在工程技术领域中难以实现。为避免小波变换复杂的数学运算和编程,科学家们研制了声表面波式小波变换器件。用声表面波器件实现小波变换继承了小波变换良好的局部化性质。声表面波式小波变换器件具有声表面波器件的优点,比如处理速度快、设计简单、体积小、温度稳定性好、价格低和功耗小。当声表面波式小波变换器件输入换能器的指条包络按照小波函数的包络设计时,能够实现小波变换,从而制作出了声表面波式指条包络加权小波变换处理器。但是该声表面波式小波变换处理器存在严重的衍射问题。衍射问题会引起衍射损耗和波前形状发生畸变。为解决衍射问题,本文研制了三种新型多尺度声表面波式小波变换处理器及小波反变换处理器,即声表面波式指条面积加权小波变换处理器及小波反变换处理器、声表面波式指条宽度加权小波变换处理器及小波反变换处理器、声表面波式指条混合加权小波变换处理器及小波反变换处理器。本文主要研究内容和创新点如下:(1)选取morlet小波函数作为三种新型多尺度声表面波式小波变换处理器及小波反变换处理器的小波函数,实现方案如下:(1)声表面波式指条面积加权小波变换处理器输入换能器的指条面积及小波反变换处理器输入换能器和输出换能器的指条面积等于小波函数的包络面积,声孔径满足H~2/λ＞D。(2)声表面波式指条宽度加权小波变换处理器输入换能器的指条宽度及小波反变换处理器输入换能器和输出换能器的指条宽度等于小波函数的包络幅值,声孔径满足H~2/λ＞D。(3)声表面波式指条混合加权小波变换处理器输入换能器的声孔径及小波反变换处理器输入换能器和输出换能器的声孔径足够大区域的指条长度等于小波函数的包络幅值,即指条长度与小波函数的包络幅值成正比,指条宽度相等;声孔径比较小区域的指条宽度等于小波函数的包络幅值,即指条宽度与小波函数的包络幅值成正比,声孔径等长。(2)根据其方案,推导出了三种新型多尺度声表面波式小波变换处理器及小波反变换处理器的物理参数(材料参数、结构参数)与其性能的关系,确定了最佳结构。(3)提出了三种新型多尺度声表面波式小波变换处理器及小波反变换处理器研制过程中的关键性问题:衍射问题、压电基片对声表面波式小波变换处理器频率特性的影响、输出换能器的指条数对声表面波式小波变换处理器带宽的影响、指条宽度的精度对声表面波式小波变换处理器频率特性的影响及相位移等。对这些问题的产生原因进行了详细分析,并提出了解决的方法。(4)在X-112°Y LiTaO_3压电基片上制作出了三种新型多尺度声表面波式小波变换处理器及小波反变换处理器的样品。通过实验测得声表面波式小波变换处理器及小波反变换处理器理论带宽值和实验带宽值相一致,且三种新型多尺度声表面波式小波变换处理器及小波反变换处理器不存在衍射问题。
[Abstract]:Wavelet transform is a time and frequency of local transform. Wavelet analysis in time domain and frequency domain also has good localization properties, especially suitable for the analysis and processing of non-stationary signals. The wavelet transform is widely used in mathematics, signal analysis, speech synthesis, image processing, quantum mechanics, electronic warfare, computer recognition, data compression analysis, seismic exploration, atmospheric and ocean, multi field of mechanical fault diagnosis. Wavelet transform algorithm requires a lot of mathematical operations and complex programming, so in the field of engineering technology is difficult to achieve. In order to avoid the complexity of wavelet transform and mathematical programming, scientists developed the wavelet transformation device of surface acoustic wave. Using surface acoustic wave device the realization of wavelet transform inherits the good localization properties of wavelet transform. The advantages of wavelet transformation device of surface acoustic wave with surface acoustic wave devices, such as processing speed Fast, simple design, small volume, good temperature stability, low price and low power consumption. When wavelet transformation device of surface acoustic wave transducer input refers to the envelope according to the envelope design of wavelet function, wavelet transform can be realized, thereby creating a surface acoustic wave type envelope weighted wavelet transform processor but the sound. Wave type wavelet transform processor has the diffraction problem serious. The diffraction problem will cause the diffraction loss and the wavefront distortion of the shape. In order to solve the problem of diffraction, we developed three novel multi scale surface acoustic wave type wavelet transform processor and inverse wavelet transform processor, namely surface acoustic wave refers to the area weighted wavelet transform and inverse wavelet processor transform processor, surface acoustic wave refers to the width of the weighted wavelet transform processor and inverse wavelet transform processor, surface acoustic wave, a hybrid weighted wavelet transform processor And the inverse wavelet transform processor. In this paper, the main research contents and innovations are as follows: (1) select Morlet wavelet function as the wavelet function of three novel multi scale surface acoustic wave, wavelet transform and inverse wavelet transform processor processor, implementation scheme are as follows: (1) surface acoustic wave refers to the area weighted wavelet transform processor input transducer means the area and inverse wavelet transform processor input and output transducer transducer refers to the envelope area equivalent to the size of the wavelet function, the sound aperture satisfies the H~2/ lambda > D. (2) surface acoustic wave refers to the width of weighted wavelet transform processor input transducer finger width and inverse wavelet transform processor input transducer and an output transducer to amplitude envelope the width is equal to the wavelet function, the sound aperture satisfies the H~2/ lambda > D. (3) surface acoustic wave sound hole mixed weighted wavelet transform processor input transducer The sound aperture size and inverse wavelet transform processor input transducer and an output transducer is large enough to envelop the area equal to the length of wavelet function, namely envelope length and wavelet function is proportional to a width equal; the sound aperture is relatively small area of the strip width is equal to the amplitude envelope of a wavelet function, i.e. the envelope width and amplitude of the wavelet function is proportional to the acoustic aperture length. (2) according to the scheme, deduces the physical parameters of three kinds of new multiscale surface acoustic wave, wavelet transform and inverse wavelet transform processor processor (material parameters, structure parameters and performance), to determine the best structure (. 3) put forward three key questions for development of a new multi-scale surface acoustic wave, wavelet transform and inverse wavelet transform processor processor in the process: the diffraction problem, the piezoelectric substrate for surface acoustic wave, wavelet transform Effect of frequency characteristics of the output of the transducer refers to the influence of number of surface acoustic wave type wavelet transform processor bandwidth, etc. the width accuracy refers to the shift effect on the surface acoustic wave, wavelet transform processor frequency characteristic and phase. The causes of these problems are analyzed, and puts forward the solving methods. (4 X-112 ~ Y LiTaO_3) in the piezoelectric substrate to produce three new multi scale surface acoustic wave, wavelet transform and inverse wavelet transform processor processor samples. Through measuring the surface acoustic wave, wavelet transform and inverse wavelet transform processor processor theoretical bandwidth value and experimental value of bandwidth is consistent, and three novel the scale of surface acoustic wave, wavelet transform and inverse wavelet transform processor processor does not exist the problem of diffraction.

【学位授予单位】：东华大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN65

【相似文献】