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为了能够有效地减少振动压路机噪声,对振动压路机噪声源的识别进行了深入地研究。首先,分析了振动压路机主要的噪声来源;其次,讨论了振动压路机噪声测试方法;最后,提出了振动压路机降噪的应对策略。 相似文献
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目前水下机械噪声源及其传递路径识别效果较难。为此,将盲源分离算法和传递路径分析方法融合和集成。视多振源信号为卷积混叠,结合LU分解,提出一种新的非正交联合块对角化方法进行耦合振动源的分离。将分离振源作为工况传递路径分析方法的输入振源,建立水下机械振动噪声源识别算法,并对潜艇舱段模型的水下振动-声辐射试验对算法进行验证。结果表明,与现存方法相比,该盲源分离算法具有易实现、收敛速度快、精度高等优点;所集成的源识别算法在水下声场预报和振源贡献量排序中的性能均优于振源耦合时的结果,与实际情况吻合好,达到了高效、准确地识别机械噪声源的目的。 相似文献
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线性振动系统加权递推最小二乘法时域参数识别 总被引:1,自引:0,他引:1
本文给出了加权最小二乘法的递推形式,并利用该方法根据自由响应的信噪比随时间逐渐降低的性质加不同的权项。在时域识别了粘性阻尼线性振动系统的复频率,并与递推最小二乘法进行了对比。通过计算机仿真和实际应用表明本文提出的方法是可靠和有效的。 相似文献
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Bearing-only passive target tracking is a well-known underwater defence issue dealt in the recent past with the conventional nonlinear estimators like extended Kalman filter (EKF) and unscented Kalman filter (UKF). It is being treated now-a-days with the derivatives of EKF, UKF and a highly sophisticated particle filter (PF). In this paper, two novel methods based on the Estimate Merge Technique are proposed. The Estimate Merge Technique involves a process of getting a final estimate by the fusion of a posteriori estimates given by different nonlinear estimates, which are in turn driven by the towed array bearing-only measurements. The fusion of the estimates is done with the weighted least squares estimator (WLSE). The two novel methods, one named as Pre-Merge UKF and the other Post-Merge UKF, differ in the way the feedback to the individual UKFs is applied. These novel methods have an advantage of less root mean square estimation error in position and velocity compared with the EKF and UKF and at the same time require much lesser number of computations than that of the PF, showing that these filters can serve as an optimal estimator. A testimony of the afore-mentioned advantages of the proposed novel methods is shown by carrying out Monte Carlo simulation in MATLAB R2009a for a typical war time scenario. 相似文献
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水下活动目标辐射噪声模拟技术被广泛应用于水下目标信号源生成、目标识别算法研究、声呐训练模拟设备和水声对抗设备研制等领域。为了给这类研究工作提供快速、便捷且有效的测试方法,文中利用水下高速运动目标的航行参数及其辐射噪声级,建立了一个数学模型用于计算目标通过一个相对固定测量点时接收到的辐射噪声级,据此设计并实现了水下高速活动目标辐射噪声模拟器。该模拟器采用人工方式设置工作参数,由嵌入式计算机在线加载,实时计算后产生航行辐射噪声模拟信号,最后通过水声信号发射机进行声输出。实验表明,该设计合理可行,满足使用要求。 相似文献
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DEMON分析是舰船噪声目标识别的重要分析手段之一。通过DEMON分析可以获得诸如舰船螺旋桨转速、螺旋桨叶片甚至舰船的车数等不变的舰船物理特征。在过去的DEMON分析中,通常采用经典的周期图方法。本文采用了高阶谱分析、小波的子频带分析以及基于互相关函数矩阵奇异值分解等方法,对舰船噪声信号进行了分析。从对大量的舰船噪声信号的分析来看,在大多数情况下现代谱分析技术具有优势,但并不是所有情况下其性能均优于周期图方法。 相似文献
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文中以宽带和多目标信号为模型,在虚拟仪器开发环境LabWindows/CVI下,设计和开发了基于PXI总线的水下目标模拟器。目标模拟器产生24阵元平面水声基阵的接收信号,在实验室里模拟海洋环境下的目标回波、混响和环境噪声,提供测试水声设备所需的各种目标信号。最后给出了该系统在水声自导系统调试和性能测试应用中的结果。 相似文献
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讨论了应用小波分析从辐射噪声中提取调制信息的方法。首先利用多尺度分析方法将噪声信号在不同层次的空间上进行分解,实现调制信号与辐射噪声的分离;然后,利用小波变换提取其包络,求取功率谱得到调制信息.在此基础上,对实测辐射噪声数据进行仿真研究.结果表明,该方法用于噪声中调制信息检测是一种有效的手段. 相似文献
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We describe a noncontact test procedure with which to obtain the shapes of fast convex surfaces. For this, an array of sources is positioned in a straight line and separated in such a way that the image by reflection on the surface consists of a set of equally spaced bright spots. By rotating the surface, we test different meridians such that, after 360 degrees, the entire surface is measured. We present the source array design and the surface evaluation algorithm. We found that, to reduce numerical error in the evaluation of the shape of the surface, a numerical integration must be performed by a method that uses parabolic arcs instead of the traditional method that uses trapezoids. Through some numerical simulations we analyzed the accuracy of the method by introducing random displacements into the measured data. We found that to measure the quality of the surface with accuracy better than 5 microm, we have to measure the coordinates of the centroids on the image plane with an accuracy better than 0.5 pixel, and we to have measure the positions of the linear sources with an accuracy better than 0.5 mm. Experimental results for the testing of a carbon fiber convex sphere of 383.6-mm diameter (f/0.398) are shown. 相似文献
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Guidi G Falteri S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1999,46(3):679-689
A new technique to measure phase distribution of ultrasound beams is presented. This method is based on the phase measurement of the Doppler signal backscattered by a moving target traveling at constant velocity, which represents a scanning element exploring the held under examination. It is produced by mechanical equipment consisting of a modified string phantom in which the commonly used cotton thread was substituted by a thin nylon thread with some tight knots over it. The thread diameter was chosen small enough to produce knots smaller than the acoustic field wavelength in order to have "pointlike" moving targets. This paper describes how the Doppler signal phase is related to the phase field and the numerical method to extract a phase field distribution from the backscattered signal. Experimental results obtained for two circular transducers, strongly and weakly focused, respectively, are finally shown and commented. 相似文献