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1.
封闭空腔结构-声耦合场内辐射声粗糙度的研究   总被引:1,自引:1,他引:0  
基于结构-声耦合场有限元模型以及改进后的Sethares非谐音心理声学模型,计算封闭空腔边界上声固耦合板受简谐力激励后引起的空腔内部辐射声,分析其在评价点被快速调制时产生的粗糙度,并研究调制音声压级、调制音频率以及耦合板刚度对辐射声粗糙度的影响。为计算封闭空腔内部声辐射被其它声源所快速调制时产生的声粗糙度提供依据和预测方法。  相似文献   

2.
以非稳态声信号为对象,针对现有小波变换计算的小波熵在反映声信号时-频特征存在的不足,提出了改进的冗余小波分解算法并构造了零相位巴特沃斯小波滤波器。通过复合的时变和频变信号,验证了基于该方法计算的小波熵能更加准确的体现信号的时变和能量分布特性。提取了反映时频能量大致特性的小波熵均值作为非稳态声品质的客观评价参数,并应用于汽车关门声品质的分析评价中,计算了该声信号传统心理声学参数,完成了声样本的主观评价试验并获得到各声样本的偏好性评价绩效值。通过主客观相关性分析表明,小波熵均值与主观评价有更高的相关性,比传统的心理声学能好的描述和预测主观评价结果。  相似文献   

3.
该文基于DSP Builder设计了一款新型高精度、高性能、宽频率范围的正弦信号发生器;通过DSP builder设计一个幅度调制模型使正弦波发生器产生的波形能够进行幅度调制。系统通过调试后,能成功产生正弦波形信号,其精度高、波形稳定、失真小。  相似文献   

4.
对基于光谱共焦技术搭建的刮板细度计斜槽面深度测量装置的非接触测量数据进行处理算法研究。引入高斯滤波对整段测量数据进行滤波分析,再分左上平面、右上平面、斜槽底面三段进行高斯滤波,分离三个测量面的表面粗糙度信号及波纹度信号,解算出粗糙度值。对于高斯滤波中线,利用最小二乘法进行拟合,结果表明左右上平面的直线倾斜度一致,可拟合为一条直线。以再次拟合的直线为基准线,求得斜槽面扫描点至基准线的深度值,得到斜槽面深度标称值为90μm的示值误差为0.27~1.97μm。与电感测微仪接触测量所得数据进行比对,结果表明本文提出的刮板细度计非接触测量数据处理方法准确可靠。  相似文献   

5.
某车车门关闭声品质评价   总被引:1,自引:0,他引:1  
汽车车门声品质是汽车声品质研究的重要内容。首先对所采集的车门关闭声音样本进行主观评价实验,并运用Bradley-Terry模型对声音样本偏好性进行分析。然后通过Head Artemis软件进行时频域分析、滤波分析和计算响度、尖锐度等心理声学参数对声音样本做出客观评价。  相似文献   

6.
为认识交流调制型直流电能表在纹波背景下的计量性能和特点,对该电能计量模型进行讨论和分析,揭示调制谐振对计量准确性的影响机理,通过仿真计算分析纹波频率、纹波功率、电量计量窗口对准确性的影响规律,通过实测验证仿真分析结论。仿真和实测结果表明,纹波频率越接近电能表调制频率,表计误差震荡趋势越明显,震荡周期越长;调制谐振状态下,纹波功率比越高,表计误差震荡幅度越大;误差震荡幅度存在极限理论峰值,该峰值与纹波视在功率、调制基准信号幅值成正比,与实际功率大小成反比;对于典型技术参数,其误差震荡幅度最大可达纹波含量比的1/2。故该型表计的调制源宜采用单一频率源,且避开典型运用场景的纹波频率,进行误差检测时应充分考虑调制谐振可能带来的影响。  相似文献   

7.
开环光纤陀螺在工作时需要对其工作点进行控制,这就要求能够用数字的方法产生一个幅度可调的正弦波调制信号。首先对光纤陀螺调制信号的数学描述进行了分析,在此基础上提出了三种幅度可调调制信号的产生方法,即直接波表法、乘法调幅法、两级波表法,并分析了三种方法各自的优缺点。比较了用不同方法产生调制信号进行工作点控制的实验结果。在大多数情况下,两级波表法是较好的选择,它可在存储容量及计算资源都有限的情况下实现工作点的精确控制。  相似文献   

8.
以驾驶员耳处采集的乘用车发动机启动时声样本为对象,分析了其时频域分布,计算了声样本的基本物理参数、心理声学参数和烦恼度指标。运用成对比较法进行了声样本主观评价实验,得出各声样本主观偏好性得分。通过主、客观参数的相关分析和回归分析表明:烦恼度模型能正确预测声样本的主观偏好性,双耳响度和粗糙度是影响主观偏好性评价的主要客观参量,用对数变换后的拟合模型能更好的描述主观评价结果与客观参量之间的关系。  相似文献   

9.
胡异丁  任伟新  杨栋  李苗 《振动与冲击》2013,32(10):181-183
非平稳信号泛指具有时变能量谱的确定性信号和具有时变功率谱的随机信号。幅度调制是非平稳性的一种表现形式。调幅信号分析主要任务之一是提取幅度随时间变化的规律。在希尔伯特变换平方解调方法的基础上,提出了利用适用于非平稳信号的希尔伯特变换低通滤波器,提取调幅信号的包络,实现非平稳调幅信号的分解。数值算例验证了方法的有效性。  相似文献   

10.
Moore响度模型的数值计算方法   总被引:6,自引:2,他引:4       下载免费PDF全文
马元锋  陈克安  王娜 《声学技术》2008,27(3):390-395
响度是最重要的声音属性之一,响度的计算是进行客观评价的基础,也是计算大多数心理声学评价参数的基础,在心理声学和声品质评价等领域具有重要意义。文章对基于Moore模型的响度计算方法进行了详细研究.阐述了算法的基本原理和计算技巧,给出了许多典型的计算结果,并对模型的改进提出了建议。  相似文献   

11.
Liu J  Tan J  Wang Y 《Applied optics》2008,47(21):3803-3807
To take advantage of phase-only filters to reduce reflected stray light, two phase plates are used in a synthetic complex superresolving pupil filter to get a small spot for laser direct writing. The amplitude modulation in a conventional complex superresolving pupil filter (CCSPF) is substituted by an equivalent phase modulation. The equivalence between the proposed filter and a CCSPF is established for a general design. The effectiveness of the proposed filter was proven through experiments to obtain a small main lobe width of 0.86 times the size of the airy spot.  相似文献   

12.
三维表面粗糙度高斯滤波快速算法   总被引:11,自引:2,他引:9  
研究了三维表面粗糙度评定基准的数学模型及采用高斯滤波器得到三维表面评定基准的数字算法 ,提出一种新的用于三维表面的快速高斯滤波卷积算法 ,该算法利用了二维高斯函数的可迭代特性和可分离性 ,其优点是大大减少了指数运算的次数 ,提高了计算速度  相似文献   

13.
Cohn RW  Horner JL 《Applied optics》1994,33(23):5432-5439
The performance of phase-only optical correlators is usually reduced if the filter-plane phase differs from that prescribed for the classical matched filter. Current spatial light modulators, which frequently produce less than 2π phase modulation, and interface circuits, which quantize or incorrectly amplify signals placed on the spatial light modulator, both can produce systematic phase errors. We examine these effects using a model of correlation-peak amplitude as a function of phase error. The correlation peak is reasonably approximated as the product of an average of unity-amplitude error phasors multiplied by the average amplitude across the filter plane. The trends predicted by this new model compare favorably with computer simulations that use gray-scale images.  相似文献   

14.
Encoding amplitude information onto phase-only filters   总被引:3,自引:0,他引:3  
We report a new, to our knowledge, technique for encoding amplitude information onto a phase-only filter with a single liquid-crystal spatial light modulator. In our approach we spatially modulate the phase that is encoded onto the filter and, consequently, spatially modify the diffraction efficiency of the filter. Light that is not diffracted into the first order is sent into the zero order, effectively allowing for amplitude modulation of either the first-order or the zero-order diffracted light. This technique has several applications in both optical pattern recognition and image processing, including amplitude modulation and inverse filters. Experimental results are included for the new technique.  相似文献   

15.
反射式近场光学显微镜样品近场光分布特性   总被引:1,自引:0,他引:1  
建立了一种反射式近场光学显微镜中样品近场光分布特性的模型,应用矢量衍射理论,得到了系统的场方程。在弱波动条件下,采用微扰法对场方程进行了求解,能方便地得到样品表面的各阶近场光反射和透射模复振幅表达式。计算结果表明,一级场分布要比零级场小一个量级,各阶近场信号的强弱完全由面形函数的傅里叶变换决定。通过与零级结果的比较,证明了计算结果的正确性。提供了一种计算样品表面近场分布简便方法,对反射式近场光学显微镜中调制检测技术具有指导意义。  相似文献   

16.
Teng HK  Chou C  Chang CN  Wu HT 《Applied optics》2003,42(10):1798-1804
A novel technique that measures the linear birefringence of crystal quartz within the configuration of a Soliel-Babinet compensator (SBC) is proposed. A characteristic of this technique is that phase retardation introduced by quartz is amplitude modulation (AM) instead of phase modulation (PM). The linear birefringence is measured regardless of the azimuth angle of the SBC and the orientation of the linear polarization laser beam. Compared with the single-wedge method, the SBC is similar to a parallel plate that allows for a wider range of refracttive index of the test material to be measured. This proposed method uses a conventional amplitude demodulation method in conjunction with an optical heterodyne technique and a bandpass filter to produce a better signal-to-noise ratio. Although the SBC configuration is more complex than a single element, the independence of azimuth angle and the orientation of the linear polarized laser beam can enhance the sensitivity of the linear birefringence measurement.  相似文献   

17.
An analytical technique for extracting phase, visibility, and amplitude information as needed for interferometric astrometry for the Space Interferometry Mission (SIM) is presented. This model accounts for a number of physical and instrumental effects and is valid for the general case of a bandpass filter. I was able to obtain a general solution for polychromatic phasors and to address the properties of unbiased fringe estimators in the presence of noise. For demonstration purposes I studied a rectangular bandpass filter with two different methods of optical path difference (OPD) modulation: stepping and ramping OPD modulation. A number of areas for further studies relevant to instrument design and simulations are outlined and discussed.  相似文献   

18.
Efficient surface gratings are UV imprinted in an acrylate-rich hybrid solgel glass. Structural changes occurring in the material upon exposure to light are investigated. Large amplitude modulation (700 nm) and low surface roughness (0.2 nm) were measured by atomic force microscopy. Diffraction efficiencies were found to be close to theoretical predictions. The method of fabrication does not involve any etching step, and an all-UV process is proposed. The gratings are resistant to temperature and to solvent effects. These devices could have useful applications in sensor and spectroscopic devices.  相似文献   

19.
A new nonlinear dynamic model of large-signal amplifiers based on a Volterra-like integral series expansion is described. The new Volterra-like series is specially oriented to the modeling of nonlinear communication circuits, since it is expressed in terms of dynamic deviations of the complex modulation envelope of the input signal. The proposed model represents a generalization, to nonlinear systems with memory, of the widely-used amplitude/amplitude (AM/AM) and amplitude/phase (AM/PM) conversion characteristics, which are based on the assumption of a practically memoryless behavior. A measurement procedure for the experimental characterization of the proposed model is also outlined.  相似文献   

20.
为了能高精度地实现表面计量中的高斯滤波,基于中心极限定理,提出了一个高斯滤波器的二阶巴特沃思滤波器逼近数学模型.用双线性变换法设计了IIR型数字高斯逼近滤波器.逼近精度可以通过调节逼近滤波器的级联阶数实现.在八阶级联的条件下,高斯逼近滤波器与高斯滤波器的幅度传输特性偏差大约只有0.25%.高斯逼近滤波器采用迭代算法实现,算法简便,易于实现.迭代算法通过合理选择初始值,可以有效抑制边缘效应.实验结果表明,在普通的双核计算机上提取11200点数据的表面中线仅需约160ms,在高精度地实现高斯滤波特性的同时,还有效地抑制了边缘效应.  相似文献   

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