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单水听器被动时反定位研究 总被引:1,自引:0,他引:1
介绍了一种基于单传感器的时间反转镜定位基本原理之后,进行了仿真和海试试验数据的验证。仿真数据处理结果表明,该时间反转镜算法能实现被动定位,且具有较高的定位精度。海试试验数据处理同样证明该单水听器被动时间反转镜定位算法的正确性,在高信噪比条件下.单水听器被动时间反转镜定位算法可实现定位。 相似文献
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针对同振型矢量水听器后期悬挂金属弹簧或橡胶绳给使用者带来不便的问题,提出一种中频同振柱型矢量水听器及其支撑结构的设计方案。通过矢量水听器振动系统对其声学特性进行分析,通过ANSYS有限元软件,利用Mooney-Rivlin理论对圆环形橡胶弹簧在压缩情况下的水平剪切刚度进行仿真计算,分析了Rivlin参数对橡胶弹簧剪切刚度的影响,并研制出矢量水听器样机。在1000~4000 Hz频率范围内,对矢量水听器进行了测试,并给出了测试结果。在1 k Hz时,声压灵敏度为-195 d B,指向性凹点深度大于20 d B。测试结果表明,此种设计免除了反复悬挂金属弹簧或橡胶绳带来的负面效应。 相似文献
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为了提高水声通信的性能,提出了一种联合运用M元扩频(MSS)通信和Pattern时延差编码(PDS)水声通信体制,并采用单阵元被动式时间反转镜(PTRM)来实现声信道均衡的深海远程水声通信方案。该方案的M元扩频-Pattern时延差编码通信技术既能胜任远程水声通信,又能提高通信速率;单阵元被动式时间反转镜信道均衡技术既可抑制多途扩展产生的码间干扰,又能提高信噪比。根据深海声道特性分析,该方案将通信固定节点置于声道轴以获取会聚增益,提高通信距离。计算机仿真结果证明,所提出的深海远程水声通信方案具有很好的鲁棒性和可行性。 相似文献
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简要介绍结构传递路径分析的基本理论,在分析车轮激励力及其传递的基础上,建立了轮胎噪声的结构传递路径分析模型,进行了轮胎噪声的结构传递路径试验,得到车内目标点由结构传递的合成声,在300 Hz以下,合成结果与实测声压在主要峰值附近吻合很好。利用频谱贡献云图和矢量叠加图分析了各结构传递路径对车内噪声的贡献,并采用矢量叠加及数据对比的方式详细分析了25 Hz时各传递路径对目标点的声贡献,从传递路径的角度找出了对车内噪声起主导作用的环节,通过控制这些环节,可以降低由轮胎引起的车内噪声。 相似文献
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为降低某型重型卡车怠速噪声,建立驾驶室声-振耦合有限元模型,测试驾驶室四个悬置点被动侧加速度数据,以此作为仿真激励载荷计算驾驶室司机耳旁声压,仿真与试验结果具有较高的一致性。针对怠速工况32 Hz、64 Hz和96 Hz峰值频率,计算各频率的模态参与因子,对模态参与因子较高的模态阶次进行叠加,获取各峰值频率对应的模态应变能分布,作为怠速噪声的控制区域。对32 Hz峰值频率,采用局部结构加强的方式进行降噪处理,单频噪声衰减量5.2 dB;对64 Hz和96 Hz的峰值频率,采用在模态应变能集中区域布置阻尼材料的方式进行降噪处理,单频噪声衰减量分别为2.2 dB和3.5 dB。通过试验测试,怠速工况驾驶员耳旁声压级降低3.2 dB,表明降噪效果良好。 相似文献
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以多变量相关非高斯过程仿真方法为基础,发展了一种基于单次采样的多变量非高斯仿真极值计算方法。首先介绍开孔屋盖的风洞试验概况和多变量相关非高斯过程仿真的基本理论,对屋盖上一组测点风压进行了非高斯仿真,结果表明基于谱修正的多变量相关非高斯过程仿真方法得到的时程在功率谱密度,相干函数,高阶矩三方面与目标值接近,仿真效果较好,然后采用经典极值理论对多次仿真的非高斯时程进行极值计算,将该方法得到的峰值因子与以往常用方法的结果进行比较,结果表明:Davenport峰值因子法高估气流分离区左偏风压的正峰值因子60%,低估负峰值因子43%;Sadek-Simiu峰值因子法低估了高峰度风压的峰值因子50%;而基于单次样本进行仿真的非高斯仿真峰值因子法,其估计的开孔屋盖的峰值因子最为准确,与观察峰值因子总体上最为接近。 相似文献
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Adeane J. Malik W.Q. Wassell I.J. Edwards D.J. 《Microwaves, Antennas & Propagation, IET》2007,1(6):1177-1181
A simple correlated channel model for ultrawideband (UWB) multiple-antenna systems is proposed. The authors show that a single numerical value of the spatial correlation coefficient is sufficient to accurately model the performance of UWB spatial multiplexing systems in an indoor environment. The appropriate value of the correlation coefficient is selected by ensuring a close match between the bit error rate results achieved on the proposed correlated channel and those on the measured indoor channel. The authors also experimentally confirm that the performance substantially degrades in the presence of high values of spatial correlation for a range of spatial multiplexing receivers, and quantify the relationship between this degradation and the value of the spatial correlation coefficient. Thus, a route for the development of the existing standards for single- antenna UWB channels to the multiple-antenna regime is provided here. 相似文献
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相关滤波算法是通过模板与检测目标的相似性来确定目标位置,自从将相关滤波概念用于目标跟踪起便一直受到广泛的关注,而核相关滤波算法的提出更是将这一理念推到了一个新的高度。核相关滤波算法以其高速度、高精度以及高鲁棒性的特点迅速成为研究热点,但核相关滤波算法在抗遮挡性能上有着严重的缺陷。本文针对核相关滤波在抗遮挡性能上的缺陷对此算法进行改进,提出了一种融合Sobel边缘二元模式算法的改进KCF算法,通过Sobel边缘二元模式算法加权融合目标特征,然后计算目标的峰值响应强度旁瓣值比检测目标是否丢失,最后将Kalman算法作为目标遮挡后搜索目标的策略。结果显示,本文方法不仅对抗遮挡有较好的鲁棒性,而且能够满足实时要求,准确地对目标进行再跟踪。 相似文献
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Raina Cepel Lori Thombs Dominic Ho Steven P. Neal 《Journal of Nondestructive Evaluation》2007,26(1):19-32
In ultrasonic NDE, simulation studies can play an important role in complimenting experimental validation of techniques under
development. The utility of such simulations depends, in part, on the degree to which the simulated defect and noise signals
are representative of the measured signals. In this paper, we describe an approach for generating simulated acoustic noise
with a spatial correlation coefficient distribution and maximum extreme value (MEV) distribution which matches those distributions
for measured acoustic noise. The procedure for generating noise signals is outlined for a line scan and for a raster scan.
The basic approach forces the correlation of neighboring signals to the desired correlation by creating each signal as the
sum of appropriately scaled neighboring signals plus a new random signal. For the line scan where each interior position has
only two neighbors, this process is done sequentially without iteration. For the raster scan where each interior point has
four nearest neighbors, iteration is required to simultaneously achieve the desired correlations with row and column neighbors.
The MEV distribution is controlled in an outer iterative loop with the shape and position of the distribution dictated by
spectral content of the noise signals and by controlling the signal energy, respectively. Results are shown which demonstrate
the effectiveness of the approach. With this approach, a limited number of measured signals can be used to establish the correlation
coefficient and MEV distributions which drive the computer generation of a large number of simulated acoustic noise signals. 相似文献
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浅海信道是一个多径信道,对于基于相关法的延迟估计,多径效应常常会导致相关函数中出现伪峰,伪峰的幅度有时会超过主峰,进而增加了相关峰选取的难度。利用 AR 法滤波对信号中的多径分量加以抑制,从而削弱了伪峰的幅度,提高了延迟估计的准确性。先从理论上论证了线性预测法可以对多径干扰进行抑制,再用仿真信号和实际信号验证了方法的效果。对于仿真信号,在无噪声干扰的条件下,选择合适阶数的滤波器可以使信号中的多径分量被完全抑制;对于正信噪比的实际信号,其中的多径分量在一定程度上被抑制,从而由多径分量产生的相关峰会被明显削弱,减少了峰值位置的跳变。 相似文献
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采用射频辉光放电等离子体壳层模型和蒙特卡罗法 ,模拟了射频磁控溅射镀膜中工作气体离子 (Ar+)的输运过程 ,得到了离子到达靶面时的入射能量、角度和位置。模拟结果 :对靶材溅射的离子主要来自于溅射坑上方的等离子体区域 ,初始离子的位置分布可通过靶材溅射坑的形貌拟合得到 ;离子的能量主要集中在壳层电压附近 ,离子大多数以垂直入射。模拟与实际相符 ,可用作进一步模拟离子对靶材溅射时的输入参数。 相似文献
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A pinched pressure-driven flow injection on a microchip is numerically simulated in order to optimize the relative values of the operational parameters. The geometry studied is a two-dimensional rectangular channel featuring a cross-junction with a large depth-over-width ratio. The hydrodynamic and convection-diffusion equations are solved for the two steps of the process: first, the sample solution is pinched into the transversal channel (injection channel), and then it is injected into the longitudinal one (separation channel), where the time evolution of the concentration is analyzed for different types of the detectors. Electroosmotic flow calculations have also been performed and have shown a good agreement with literature. The results for pressure-driven flow point out that the shape of the detection signal is strongly dependent on the velocity in the separation channel and on the position of the detection probes. The so-called double-humped peak, caused by the parabolic flow profile at high driving flow rate is analyzed. A tight pinch greatly decreases the amount of injected sample and, consequently, the signal sensitivity without increasing its quality. A proper pullback of the sample during the separation process can decrease the tailing due to the sample leakage from the injection channel. Although a high sample pullback causes a considerable decrease in the signal sensitivity, it also greatly enhances the peak resolution. Finally, it is shown that a wider injection channel with high sample pullback ensures an improved signal sensitivity with good resolution. 相似文献
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外加磁场对磁控溅射靶利用率的影响 总被引:1,自引:1,他引:0
通过在基片上直接放置一块永久磁铁来研究外加磁场对磁控溅射靶利用率的影响。实验发现 ,外加磁场的引入改变了靶表面附近的磁场分布 ,因而靶的刻蚀环的位置、宽度和深度均发生了明显的变化 ,靶的利用率在S S构型和S N构型中均比无外加磁场时要高。利用空间模拟磁场成功的解释这一实验现象。在S S构型和S N构型中 ,后者靶的刻蚀深度轮廓线比较平坦 ,相对刻蚀深度值更大 ,更能有效地提高靶的利用率 相似文献