The thought that sampling frequency in targets measure system confirm as 3 is studied for the first time . it is proved from three aspects : the frequency spectrum of track , the error requirement of project and the rate of maximum number of allowable lost points in project 本文首次就目标坐标测定仪中采样频率确定为3hz的思想进行了研究，并分别从目标航路功率谱密度、实际工程中误差要求和允许的最大漏测点概率等三方面加以论证。
The measurement was made on a gas - solid fluidized bed in our laboratory . the pressure fluctuation signals were obtained and analyzed through power spectrum density . the relation of the particle size to pressure fluctuation and other parameters was studied by using fuzzy set theory 在实验室条件下对气-固流化床的颗粒进行了测量，通过功率谱密度对所获得的压力波动进行了分析，并应用模糊集理论对颗粒尺寸与压力波动及其它影响参数的关系进行了研究。
With the nonlinearity of vehicle suspension , simulation signal of suspension system is more practical by road exciting signal of time domain than frequency domain , furthermore , it is easy to get the results which are consistent with practical results 考虑到车辆的非线性因素，在进行主动控制分析过程中，悬架系统激励信号采用时域信号。因此，首先进行了时域路面随机不平度生成方法的研究，所得路面模型的功率谱密度与理论路面功率谱密度吻合较好。
The basic concepts of second - order coherence theory in describing wavefields are introduced . these concepts are the cross - spectral density function and spectral degree of coherence in the space - frequency domain , and the mutual coherence function and the complex degree of coherence in the space - time domain 介绍了二阶相关理论中描述光场相干性质的基本概念，包括空间-时间域中的互相关函数、复相干度和空间-频率域中的交叉谱密度函数、光谱相干度。
To solve it , the differential equation set is transformed by fourier transform and the dynamic differential equation in the form of matrix is educed . the calculation formulas of frequency response function of vehicle vibrating system , acceleration power spectrum density function are put forward 用分析力学法建立整车动力学模型，推导出以矩阵形式表示的运动微分方程，并通过傅氏变换给出汽车动力学系统的频率响应函数、加速度功率谱密度函数的计算公式。
Based on priestley ' s evolutionary spectrum theory , an evolutionary process modulated by decline composite exponential function , is investigated as one kind of non - stationary excitation commonly encountered in engineering , the analytical solution of the response properties is gained due to proper simplification 基于priestley的演变谱密度理论，对于工程中常用到的衰减指数函数调制的演变过程激励，可以通过对结构响应的合理简化，得到响应特征的解析形式。
The response curve of rear left hydraulic mount , rear right hydraulic mount , and the fore rubber mount in each conditions are draught . the curve of hydraulic mount system ' s transmissibility is also calculated in the end and the performance of vibration isolation is analyzed . 5 绘制了在时域和频域上的动力总成的加速度运动响应，质心的角加速度运动响应以及后左，后右液压悬置，前橡胶悬置的动反力曲线，以及怠速，高速工况下各悬置的加速度功率谱密度曲线。
In the dissertation , two kinds of computationally efficient algorithms ( including ssca and fam ) for cyclic spectral analysises have been discussed detailly and deeply after introduce of the theory of spectral correlation , in addition , digital implementations of the corresponding algoritms architecture and the comparision of computational complexity are presented 本文在简要介绍了循环谱理论的基础上,对两种高效循环谱密度函数的计算方法(分段谱相关函数算法( ssca ) 、 fft累加算法( fam ) )进行了详细而深入的讨论,给出了两种算法结构的数字实现,比较了各种方法的运算复杂度。
Abstract : to against the fact of the commercial available white noise generators are very expensive which is not good for general operations , a simple and effective limited band white noise generator is design . the generator is using the feature of dual polarity transistor , i . e . , the power spectrurn density of particulate noise is not related to frequency in very wide band and close to white noise . the concrete circuit is also given 文摘:针对市售白噪声发生器价格昂贵，不利于一般场合使用的问题，介绍利用双极性晶体管散粒噪声功率谱密度在非常宽的范围内与频率无关，属白噪声这一特性，设计了一种简捷、有效的限带白噪声发生器，并给出了具体电路。
Based on the propagation law of the cross - spectral density function in the space - frequency domain , the properties of polychromatic vector gsm beams through a paraxial optical abcd system are studied . the analytical propagation expressions for the cross - spectral density matrix of vector gsm beams passing through a paraxial optical abcd system are derived , which permits us to study the propagation properties of vector gsm beams , including the propagation - induced polarization changes , effect of the spectrum bandwidth and irradiance distributions in a unique way . there are some applications of the theoretical results 基于空间一频率域中交叉谱密度函数的传输理论，研究了多色矢量gsm光束通过abcd光学系统传输时偏振特性的变化规律，首次推出了矢量高斯一谢尔模刑fgsm )光束通过近轴abcd光学系统交叉谱密度矩阵的传输公式，并对矢量gsm光束传输中偏振的变化、谱宽的影响和强度的分布等进行了统一研究。
