共查询到20条相似文献,搜索用时 164 毫秒
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裂纹转子非线性振动特征的谐波小波与分形识别 总被引:2,自引:2,他引:0
通过对谐波小波的分析研究,指出了谐波小波对振动信号局部频段分析的优良特性。采用谐波小波对裂纹转子的非线性振动信号在低频段进行了分析。理论分析与实验结果表明:对实际裂纹转子信号,经谐波小波的频段分析后,能够得到通常难以由理论分析与实验结果获得的非整数倍周期分叉的非线性特征频谱。计算了裂纹转子的分形维数,发现裂纹转子的振动信号比理论结果要复杂、可以用多重分形作为判断实际转子是否有裂纹的一个特征。提出了用谐波小波变换后的奇异谱来识别裂纹转子非整数倍周期分叉的非线性特征频谱的方法,并对实际转子信号进行分析,得到了明显的非整数倍周期分叉的奇异谱。 相似文献
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信号周期分段处理法诊断单级传动齿轮副故障 总被引:1,自引:0,他引:1
为了诊断单级传动齿轮副故障,本文提出信号周期分段处理的方法。首先同步整周期采集振动信号,然后对采集的振动信号做时域平均,进行降噪和凸显故障脉冲的处理。利用周期分段处理法,将振动平均信号等距分段,分别对各段信号进行频谱分析。比较各段信号的时域波形和频谱的异同,可以准确诊断出单级传动齿轮副中同步齿轮故障位置,且还能诊断出非同步齿轮故障位置。数字仿真试验以及模拟故障实验结果都证实了信号周期分段处理法诊断齿轮故障的可行性和有效性;它为诊断单级传动齿轮副故障提供一种有效手段。 相似文献
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王艳丰郜伟强滕光蓉敬发宪何伟 《燃气涡轮试验与研究》2021,34(5):39-43
航空发动机轴承发生故障时,其振动信号受周期脉冲力的影响多为含噪非平稳随机信号,采用传统的频谱分析法很难提取轴承故障的振动特征.对双谱进行对角切片处理形成降维双谱,并将其引入到航空发动机轴承故障振动信号分析中.采用降维双谱对仿真和实测的发动机轴承磨损振动数据进行处理,成功提取到轴承振动信号的调制频率成分,并准确判定故障.... 相似文献
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文中提出了一种自适应非均匀采样方法,并利用分数阶Fourier变换对这类非均匀采样信号在分数阶域的频谱进行了分析和研究,得到了这类非均匀采样信号在分数阶域的数字谱表达式;进一步得到了非均匀采样Chirp信号的分数阶频谱表达式;最后,通过仿真验证了结论。 相似文献
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无位置传感器的中低速运行控制是开关磁阻电机研究的难点问题。为实现中低速阶段对转子位置的连续估计,提出一种基于PWM控制的无位置传感器方法。该方法将开通关断角所对应的参考信号与高频三角载波进行交截,并将得到的PWM信号作为不对称半桥功率变换器的开关管驱动信号。通过对PWM信号进行频谱分析可知,该PWM注入方式等效于注入载波频率的高频正弦信号。然后,对电流信号进行滤波及坐标变换处理,解算出连续的转子位置信息。针对电感曲线正弦度不高的问题,通过移相相减的方法消除二次谐波,简化了位置估计过程。该方法无需额外注入高频正弦信号,易于工程实现,并具备高频信号注入法的精度。最后针对一台12/8结构样机,进行了相应的仿真和实验,验证了该方法的可行性。 相似文献
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齿轮振动信号常表现出明显的非线性和非平稳特征。为有效提取齿轮振动信号的特征信息,将自适应信号分解方法——局部均值分解用于齿轮振动信号的分析。使用局部均值分解对三种状态的齿轮振动信号进行分解,得到一组PF分量,并对PF分量进行频谱分析。分析结果表明,局部均值分解完成了对齿轮振动信号的有效分解,各PF分量的幅值谱获得了不同状态齿轮振动信号的特征谱线,实现了对齿轮状态特征的准确提取。 相似文献
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A periodic ambiguity function (PAF) is discussed which describes the response of a correlation receiver to a CW signal modulated by a periodic waveform, when the reference signal in the receiver is constructed from an integral number N , of periods T , of the transmitted signal. The PAF is a generalization of the periodic autocorrelation function, to the case of non-zero Doppler shift. It is shown that the PAF of N periods is obtained by multiplying the PAF of a single period by the universal function sin(N πν T )/N sin(πνT ), where ν is the Doppler shift, to phase-modulated signals which exhibit perfect periodic autocorrelation when there is no Doppler shift. The PAF of these signals exhibits universal cuts along the delay and Doppler axes. These cuts are functions only of t , N and the number M , the modulation bits in one period 相似文献
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基于神经网络模型的动态非线性气动力辨识方法 总被引:1,自引:0,他引:1
在标准径向基函数(RBF)神经网络模型的基础上发展了带输出反馈的RBF神经网络。将计算流体力学(CFD)方法计算的时域气动载荷作为输入信号,建立跨声速非定常非线性气动力模型,并进一步运用CFD方法验证模型的精度。算例表明带输出反馈的RBF神经网络较标准RBF神经网络精度更高,能更准确描述跨声速激波大幅振荡时的非线性和非定常特性,并可推广用于多自由度运动的动态非线性气动力建模。用多级信号训练,预测简谐信号输入下的气动力算例表明带输出反馈的RBF神经网络能够预测不同振幅、不同频率的信号激励下的非线性气动力。 相似文献
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由天线阵对被测信号的响应矩阵的特征值,可得到对应于信号和噪声的特征向量,以此扩展成信号子空间和噪声子空间。利用信号子空间与噪声子空间的正交关系,即可求得信号方位角的估计值。这种空间谱估计测向的MUSIC算法,用于圆形天线阵对非相干信号进行测向,可以克服一般干涉仪测向体制中测向模糊和测向盲区的问题。 相似文献
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Xu Qing-Chen Yang Zi-Jie Hu Xiong 《IEEE transactions on aerospace and electronic systems》2009,45(1):209-220
High resolution radars require signals with large time-bandwidth product such as CW signal and coherent pulse train (CPT). We discuss a phase-coded interrupted CW (ICW) signal which is the combination of CW signal and CPT. Phase codes used here are with perfect periodic autocorrelation. The periodic ambiguity function of ICW signals is studied including single-carrier signal and multi-carrier signal. It is interesting that the gate function has different effects on two signals and contributes to a multi-carrier ICW signal which yields nearly perfect autocorrelation. Meanwhile we also suggest an efficient receiver approach to ICW signals, which can reduce the computational burden of the processor and utilize the good properties of P3 and P4 codes. 相似文献
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Skolnik M. Andrews G. Hansen J.P. 《Aerospace and Electronic Systems Magazine, IEEE》1995,10(10):25-30
This paper outlines the special considerations that characterize the design of an UWB radar for the detection of low-altitude missiles over the sea. It discusses the factors which enter into the choice of frequency, and the selection of the transmitter, antenna, and receiver. Reviewed are signal processing issues concerning detection of UWB signals in noise and clutter, nondoppler MTI based on the pulse-to-pulse change in range due to target motion, measurement of target height based on multipath time delay, and target recognition. As the investigation progressed, the authors became disappointed with the available UWB technology, but encouraged about the potential advantages of UWB for this application. The chief limitation of UWB radar that must be overcome before applications are viable is its poor electromagnetic compatibility (EMC) 相似文献
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Farrell Edward J. Kau Peter S. 《IEEE transactions on aerospace and electronic systems》1968,(4):615-619
Beam splitting for a radar beacon system that scans in azimuth is investigated from a theoretical viewpoint. The video output is quantized into two levels corresponding to a detection and no detection. Further, the antenna sensitivity profile is described by sin ?/?. For this system, a digital method of beam splitting that minimizes angular error is developed. Prior information about the probable location of targets can be included. Both Bayesian and minimax approaches are developed. The minimax estimate of the target azimuth is the average of the angles at which beacon signals are detected. The antenna beam can be interpolated by a factor of 10 when the signal power is 3 dB above the noise and without prior azimuth information The interaction of beam splitting and detection is discussed. 相似文献
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给出了利用电力系统模块(PSB)工具箱对仿真波形进行频谱分析的一种新方法.该方法以MATLAB提供的PSBFFT_SCOPE函数为基础,对其输入变量加以改造,克服了其不能应用于变步长算法模型频谱分析的缺陷,拓宽了在PSB工具箱中进行频谱分析的范围.实际仿真结果表明,该方法分析正确,使用简捷,在实际仿真过程中是切实可行的. 相似文献