共查询到20条相似文献,搜索用时 15 毫秒
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针对常规统计最优近场声全息在空间多源声场重建过程中所需波函数项数多、重建精度不理想的问题,本文提出了一种基于振速测量的改进统计最优近场声全息算法。与常规算法不同,改进算法主要根据声源特点选取合适的波函数组合来计算声场传递矩阵。通过数值仿真初步验证了该方法的准确性和有效性,并与常规算法进行了详细的对比分析。仿真结果表明,改进算法重建精度高,随频率的变化相对误差波动较小,且随着频率的增大相对误差有逐渐减小的趋势;此外,不同的波函数组合,重建效果差异很大,当选取的波函数与声源共形且数量一致时重建效果最好。 相似文献
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测量孔径尺寸的有限性,在基于空间傅里叶变换的平面近场声全息中会带来窗效应和卷绕误差. 为了克服窗效应和卷绕误差,引入了统计最优平面近场声全息技术. 运用声场叠加原理,证明了统计最优平面近场声全息的理论公式.通过在空间波数域限定kx,ky的取值范围,并离散其确定的空间波数面的途径,提出了一种确定波数矢量的方法.为了克服常规统计最优平面近场声全息技术的应用局限性——全息面一侧的声场必须为自由声场,提出了适用于统计最优平面近场声全息的、基于双全息面测量的空间声场分离技术. 通过实验和数值仿真对理论推导的正确性进行了验证.
关键词:
统计最优
平面近场声全息
波数矢量
声场分离 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2010,(6)
Hybrid near-field acoustical holography(NAH) is developed for reconstructing acoustic radiation from a cylindrical source in a complex underwater environment. In hybrid NAH,we combine statistically optimized near-field acoustical holography(SONAH) and broadband acoustical holography from intensity measurements(BAHIM) to reconstruct the underwater cylindrical source field. First,the BAHIM is utilized to regenerate as much acoustic pressures on the hologram surface as necessary,and then the acoustic pressures are taken as input to the formulation implemented numerically by SONAH. The main advantages of this technology are that the complex pressure on the hologram surface can be reconstructed without reference signal,and the measurement array can be smaller than the source,thus the practicability and efficiency of this technology are greatly enhanced. Numerical examples of a cylindrical source are demonstrated. Test results show that hybrid NAH can yield a more accurate reconstruction than conventional NAH. Then,an experiment has been carried out with a vector hydrophone array. The experimental results show the advantage of hybrid NAH in the reconstruction of an acoustic field and the feasibility of using a vector hydrophone array in an underwater NAH measurement,as well as the identification and localization of noise sources. 相似文献
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由于运动声源测量信号中多普勒效应的存在,一般声全息方法无法直接使用,而阵列信号波束成形处理方法无法进行定量分析.本方法建立了基于测量面、辐射面和全息面的运动学几何关系,提出了声源与测量信号之间的非线性时间映射方法,基于运动声源的声源特征函数,构造了消除多普勒效应的全息面时域声压分布.全息重建得到运动声源表面有效声压分布,实现了对主要声源处声压幅值的定量估计.实际运动声源的测量实验结果证明了该方法的有效性. 相似文献
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The current main approach to reconstruct and predict the acoustic field of a planar source is Near-field Acoustical Holography (NAH) based on FFT. But this method has some disadvantages such as wraparound error and edge Gibbs phenomena which will contaminate the results badly. A planar NAH based on equivalent source approach is developed, which has no wraparound error and edge Gibbs phenomena, and it is beneficial for engineering application. The experimental results of acoustic radiation generated by a point-driven plate with clamped boundaries validate the correctness and availability of the method. 相似文献
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Nearfield acoustic holography in a moving medium based on particle velocity input using nonsingular propagator 下载免费PDF全文
Nearfield acoustic holography in a moving medium is a technique which is typically suitable for sound sources identification in a flow.In the process of sound field reconstruction,sound pressure is usually used as the input,but it may contain considerable background noise due to the interactions between microphones and flow moving at a high velocity.To avoid this problem,particle velocity is an alternative input,which can be obtained by using laser Doppler velocimetry in a non-intrusive way.However,there is a singular problem in the conventional propagator relating the particle velocity to the pressure,and it could lead to significant errors or even false results.In view of this,in this paper,nonsingular propagators are deduced to realize accurate reconstruction in both cases that the hologram is parallel to and perpendicular to the flow direction.The advantages of the proposed method are analyzed,and simulations are conducted to verify the validation.The results show that the method can overcome the singular problem effectively,and the reconstruction errors are at a low level for different flow velocities,frequencies,and signal-to-noise ratios. 相似文献
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针对区域有源降噪问题,为获得更优降噪效果,根据实际次级通路传递函数,提出次级声源优化布放的有源控制系统并详细比较了两种次级声源优化布放算法与次级声源均匀布放的实际降噪效果。应用的第一种次级声源优化算法是l2范数约束的约束匹配追踪算法,第二种次级声源优化算法是l1范数约束的稀疏正则化方法。在全消声室中利用扬声器线阵进行多通道有源降噪实验研究,实验结果表明,在200~1000 Hz,次级声源优化布放的控制系统的平均降噪量比次级声源均匀布放的控制系统的平均降噪量多5 dB左右;在1100~1900 Hz,次级声源优化布放的控制系统的平均降噪量比次级声源均匀布放的控制系统的平均降噪量多11~13 dB左右,次级声源优化布放的控制系统的降噪量分布更加均匀且次级声源输出能量更小。此外,两种优化算法中,稀疏正则化方法的降噪效果更佳。 相似文献
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In this paper, a new lensless digital holography system with short-coherence light source is reported for recording three-dimensional surface contouring of reflecting micro-objects. In the experiment, each of the layers on the inwall of a conical pore is respectively recorded by changing the path length of the object beam, instead of changing that of the reference beam, which can reduce the recording complexity and errors. In addition, the least-square-polynomial-fitting is used for the first time to carry out three-dimensional reconstruction with a series of two dimensional intensity images of a micro-object, which can be used not only to reduce obviously the complication of the three-dimensional reconstruction, but also to carry out three-dimensional reconstruction of a micro-object with strong laser speckle noise, of which the phase images can not be obtained from the conventional phase unwrapping process. 相似文献
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基于被动合成孔径原理,提出了一种具有高稳健性的运动声源高分辨聚焦定位识别方法.该方法采用综合优化手段,通过矢量最大似然聚焦定位算法生成虚拟阵列坐标及数据矩阵,进而利用基于最差性能优化的稀疏虚拟阵列聚焦算法,获取稳健的高分辨定位识别效果.理论及仿真研究表明,该方法对于非匀速运动以及与基阵存在运动倾角的复杂情况具有较强的适用性,聚焦空间谱表现出更大的动态范围、更为尖锐的聚焦峰尺度以及更强的背景噪声起伏压制能力.湖上试验进一步验证,在高分辨最小方差信号无畸变响应法(MVDR)聚焦算法动态范围仅为3.5 dB的相
关键词:
稳健性
运动噪声源定位识别
矢量阵
最差性能优化 相似文献
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在近场声全息技术的基础上,研究了基于声压-质点振速测量的单面声场分离技术.分析了现有基于Fourier变换的单面声场分离技术中的奇异性问题,并应用波数域谱平均法提出了去除奇异性的修正声场分离公式.为改善分离效果,减小由于Fourier变换引起的卷绕误差等因素的影响,基于统计最优近场声全息提出了一种新的单面声场分离方法.通过仿真分析对各种单面声场分离方法做了比较,并用Microflown公司的声强探头做了基于声压-振速测量的单面声场分离实验研究,验证了提出的修正公式和基于统计最优单面声场分离方法的正确性和有效性.
关键词:
声场分离
近场声全息
统计最优
Fourier变换 相似文献
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运动声源的边界元声全息识别方法研究 总被引:3,自引:1,他引:2
提出了一种可实现任意形状的运动结构噪声源识别的声全息方法。通过结合移动框架技术与边界元声全息技术两种算法的特点,提出利用移动框架技术将存在多普勒效应的时域数据转换成边界元声全息所需的双平面全息数据,然后由边界元法声全息公式重构任意结构表面的声学信息,实现运动结构噪声源定位。该方法既具有移动框架技术处理运动问题的快速简便,又具有边界元方法可处理任意形状问题的特点。最后在半消声水池中,对运动速度为9.96 cm/s的带帽圆柱壳体进行了试验验证,结果表明:在低速条件下,该方法能够准确反演得到该结构的表面有功声强以及声压等声场信息,从而实现噪声源定位。由于条件有限,高速验证需进一步验证。 相似文献
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为准确、快速获取拉索结构索力,该文提出利用结构近场固定位置辐射声压信号对拉索进行索力测试的方法。基于动力学理论推导出结构振动加速度响应与其近场辐射声压响应的线性比例关系,并根据希尔伯特-黄变换推导了声压响应信号与结构频率的关系。对单根拉索依次施加3种不同工况的初始张拉力,并对结构中心表面处施加一瞬时脉冲力,使拉索受迫振动发声,通过对结构近场范围内拉索振动辐射声压进行测量,进而获得不同工况下不同位置声压响应信号,并探讨了在有高斯噪声干扰情况下通过希尔伯特-黄变换方法获取拉索固有频率的可靠性。数值模拟分析验证了该方法能较为准确地得到拉索固有频率并利用索力计算实用公式有效地计算出索力值,为实际工程中拉索索力测试提供了一种新的简单有效的方法。 相似文献
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本文基于被动合成孔径原理, 在建立运动声源矢量阵近场柱面聚焦测量模型的基础上, 分别研究了适用于单频线谱信号和宽带连续谱信号的矢量阵柱面聚焦定位方法, 通过数值仿真计算了该方法在多种误差条件下的定位精度, 并进一步通过舱段模型试验对该方法的工程实用性和正确性进行了详细的分析和论证. 舱段模型试验结果表明, 柱面聚焦定位结果与壳体振动能量分布规律符合较好, 该方法不仅能真实反映声源位置信息, 而且能反映不同频带内声源能量分布的相对大小, 具有良好的定位效果. 相似文献
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Based on the whole process of the recording and reconstruction of digital holography, we study the formation cause of speckle noise in its reconstructed image and acquire the conclusion that the small size of hologram aperture diffraction aggravates the speckle noise of reconstructed image and the speckle noise has been one of primary noise sources in the reconstruction process. In order to reduce the speckle noise resulting from little hologram aperture diffraction, we set an appropriate aperture function matching the recording parameter and aperture size of hologram and deconvolve the reconstructed image with it. The validity has been proved in theory and experiment. Therefore, it offers a brand-new thought and practical way to reduce the speckle noise in the reconstructed image of digital holography. 相似文献