共查询到19条相似文献,搜索用时 46 毫秒
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图像处理在众多领域中都有广泛应用。离散小波变换(DWT)是信号和图像处理领域里一个十分有用的工具,但它只能从出垂直、水平和对角三个方向进行图像分解,得到的相位信息有限。基于映射的复小波变换具有良好的方向性和平移敏感性,易于得到清晰的相位信息。将映射理论与复小波变换技术结合进行实验分析。结果证明,基于映射的复小波变换可以很好的实现图像的多角度分解和完全重构,且设计简单,具有广泛的应用前景。 相似文献
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利用小波变换对单质点弹性体系进行小波分析,给出了单质点弹性体系在脉冲响应下的输出信号的小波变换与该体系的输入信号的关系.作为算例,计算了在水平地震作用下单质点弹性体系的Har小波变换. 相似文献
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《Planning》2013,(25)
小波变换是被广泛应用到许多科研领域的有效频率分析工具。小波变换有两种实现方式:直接逐点内积法和快速小波算法(Mallat算法和小波包算法)。逐点计算方法需要的运行时间较长,在处理数据量较大时效率很低;而快速小波算法只是针对正交小波的离散小波变换,具有局限性。利用卷积定理和Fourier变换的相似性定理,可以将时域的小波变换内积变换到频域的内积形式,从而可以利用Fourier变换的快速Fourier算法来实现小波变换。本文利用随机产生的10000个数据,分别用直接逐点内积算法和Fourier算法计算序列的小波变换。运行结果表明,Fourier算法能够明显缩短小波变换的计算时间,大大提高了运算的效率。 相似文献
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指出了相对于传统的傅里叶变换,小波变换具有良好的时频局域化能力,介绍了小波变换的基本概念和小波奇异性检测原理,算例表明,小波变换能快速地检测出信号的奇异点(突变点),为结构损伤诊断提供了全新的技术手段。 相似文献
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解决海量遥感影像存储和传输问题的有效方法是对影像进行保真快速压缩.本文对基于小波变换的遥感影像压缩技术进行深入探讨,并通过与其他图像压缩算法相比较,比较全面地揭示出小波压缩算法的特点及其在遥感影像压缩中的应用. 相似文献
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《Planning》2013,(Z1):197-200
由于受各种因素的影响,变形观测数据可能包含各种各样的误差与变形信息,但仅从这些数据表面上,不能反映形变的任何信息,所以,必须通过对监测数据进行综合处理分析,才能有效地提取变形信息,发现变形规律。本文利用小波多尺度分解,结合变形监测实例,从数据去噪方面对小波变换在GPS变形监测数据处理中的应用进行了研究。通过对处理结果做了详细分析,利用小波变换的多分辨率特性,实现了GPS动态监测数据的滤波、变形特征信息的提取以及不同变形频率的分离,有效的求解变形的非线性系统问题,验证了基于小波理论的GPS变形监测数据处理方法的可行性与有效性。 相似文献
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《Planning》2014,(21)
信号的突变性或奇异性经常携带有比较重要的信息,它是信号重要的特征之一。本文介绍了小波变换的基本概念,讨论了小波变换的奇异性检测方法,可以应用于海洋声波信号的奇异性检测。阐述了高斯和Daubechies小波函数的信号奇异性检测原理及其MATLAB仿真实现,分析了信号奇异点的定位方法和小波检测效果,并指出了利用此方法时对所用小波函数的要求及小波尺度的选取对检测结果的影响,为非平稳信号的奇异性检测的研究提供了一种行之有效的方法。 相似文献
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针对短时交通流时间序列的缺点,应用小波变换理论,将含有综合信息的时间序列分离为低频确定信号和高频干扰信号,用遗传过程神经元网络分别进行预测,得到了原时间序列的实际预测结果,通过实测数据验证表明,该预测方法具有较好的预测精度。 相似文献
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介绍了利用小波变换对获取的磁记忆检测信号进行去噪处理的三种方法,指出基于小波变换的非线性方法能够获得较理想的处理效果,详细介绍了基于该方法的信号处理原理,并重点探讨了影响去噪效果的三项因素,以推广该法的广泛使用。 相似文献
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《Structure and Infrastructure Engineering》2013,9(7):897-903
It is highly necessary to evaluate strength development during the curing process to ensure the quality of concrete in construction using concrete. In particular, curing strength monitoring at early age is very important to reduce the construction cost and time, because it can provide the information required for the decision-making to safely progress to the next process. In this study, a guided wave-based non-destructive curing strength gain monitoring method that can be used even for early-age concrete is proposed. A steel plate-type piezoelectric sensor module was embedded in the concrete media at the same time as concrete placement to measure the signal from early-age concrete. The guided wave signals were measured continuously using the pitch-catch method at regular intervals. The wavelet transform process was performed to improve the quality of the signal. The guided wave's velocity of each measurement time was varied by extracting the time of flight. The wave velocity hysteresis curve according to the curing age was traced to analyse the variation patterns. Finally, a specific equation to estimate the curing strength without destructive test was derived using regression analysis based on the wave velocity hysteresis and the results from the compression test. 相似文献
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基于强震时断层附近地面地震动转动分量对单摆式地震仪水平和竖向摆造成的响应差异性,建立采用小波分析获取地震动转动分量的方法。首先采用离散小波变换探讨未修正地震动水平和竖向分量的局部时频特性;进而在水平和竖向分量低频差异性的基础上,建立新的阈值处理方法对水平分量的小波系数进行处理,从而获取了地震动转动分量;最后,通过振动台试验验证了基于小波分析的地震动转动分量获取方法的正确性和精度。结果表明:基于小波分析获取的地震动转动分量的残余倾斜位移与实测的基本吻合,且过滤掉转动分量的水平分量傅里叶谱的低频部分与竖向分量的较为相似;振动台试验验证了基于小波分析获取地震动摇摆分量方法的正确性,且相较于基于傅里叶分析的方法,结果与实际情况更加吻合,精度实现了大幅提高。 相似文献
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《Structure and Infrastructure Engineering》2013,9(1):106-127
In this study, the applicability of continuous wavelet transform (CWT) and discrete wavelet transform (DWT) for seismic damage detection of tall airport traffic control (ATC) towers was investigated. Nonlinear finite element (NFE) model of Kuala Lumpur International Airport (KLIA) ATC tower with the height of 120 m was created using discrete moment-curvature hinges. Three different strong ground motions excited the tower and three different damage scenarios were then obtained. Response accelerations at four strategically selected locations were analysed by CWT and DWT to detect the damage scenarios. It was found that CWT successfully detects seismic-induced damage even when the signals are polluted by noises. On the other hand, DWT is quite sensitive to noisy signals and successful damage detection by DWT depends on noise level and sampling interval. Moreover, it was observed that DWT is more sensitive to the change in the stiffness of the tower structural elements than CWT. 相似文献
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In this article, the Continuous Wavelet Transform (CWT) is used to study the amplitude dependency of the natural frequency and the equivalent viscous modal damping ratio of the first vertical bending mode of a ballasted, single span, concrete-steel composite railway bridge. It is shown that for the observed range of acceleration amplitudes, a linear relation exists between both the natural frequency and the equivalent viscous modal damping ratio and the amplitude of vibration. This result was obtained by an analysis based on the CWT of the free vibrations after the passage of a number of freight trains. The natural frequency was found to decrease with increasing amplitude of vibration and the corresponding damping ratio increased with increasing amplitude of vibration. This may, given that further research efforts have been made, have implications on the choice of damping ratios for theoretical studies aiming at upgrading existing bridges and in the design of new bridges for high speed trains. The analysis procedure is validated by means of an alternative analysis technique using the least squares method to fit a linear oscillator to consecutive, windowed parts of the studied signals. In this particular case, the two analysis procedures produce essentially the same result. 相似文献
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简要阐述了一维小波分析的基本原理和计算方法,并介绍了国内外专家学者利用小波分析在风工程中的研究成果,由此可知小波分析在人工风速时程模拟、风速时程信号扩展、风速能量诊断和风致动力反应计算分析方面具有独特的应用价值,这些都是值得探索的。 相似文献