By digital simulation and detection of gearbox fault signal the detection effect of the novel bilinear time - frequency transform is validated for the transient components in complex signal 通过数字模拟实验与齿轮箱故障信号检测，验证了新的双线性时间频率分布对复杂信号中瞬时分量的探测效果。
If topic # 1 is not presented , this proposed seminar could include a brief overview of the fundamentals of time and frequency metrology and standards as in # 1 , before focusing in more depth on practical metrology 如果上一专题未宣讲，应先做一个时间频率计量学基础的简要介绍，然后才可以着眼与深入的实践计量学。
Description of some of the expected future developments in time and frequency standards and distribution , including such topics as chip - scale atomic clocks ( size of a rice grain , powered by aa battery , potentially capable of low cost mass production ) 介绍一些未来可预期的时间频率标准和发布技术的进展，包括诸如“芯片级的原子钟” （大米粒尺寸，由aa电池供电，具有低成本大批量生产潜力） 。
To detect transient signals under complex background , a novel method of aliasing - free exponential bilinear time - frequency distribution is presented in this paper , which can avoid the frequency aliasing and information loss existing in the traditional bilinear distributions , reduce the cross - terms effectively and possess high time - frequency resolution 摘要针对复杂背景条件下瞬时信号的探测，提出一种新的无混叠双线性时间频率分布方法，该方法能够避免常用的双线性时频分布中的频率混叠与信息丢失，有效减小交叉项干扰，而且具有较高的时频分辨率。
With regard to some specific problems encountered in the process , the pointed answers are given by way of simulative experiments in laboratory . those problems are as follows : the relation between rt curve and rasti , different impacts caused by different acoustic characteristics on different standing waves , the changes of acoustic quality derived from different positions of sound absorption materials 而对此过程中遇到的某些特定问题，如：混响时间频率特性与清晰度的关系，不同声学特性对驻波的影响，吸声材料摆放位置不同带来的音质的变化等，则以在实验室模拟实验的研究方式予以针对性的回答。
In section 4 , by making use of the fourier transformation for spatial variables and starting from the nonparaxial propagating equation of ultrashort pulsed beam in temporal frequency domain , the nonparaxial solution basing on the paraxial propagating solution was derived , which come to exact solution by iterative of the paraxial integral solution 在第四节里，通过采用空间变量的傅立叶变换和利用时间频率域下的非傍轴传输方程，我们得出了超短脉冲光束传输的非傍轴的修正方法。
A systematic project of the platform for time - frequency signals measurement and analysis with high precision is put forward in this thesis . the platform consists of two mixers , a pc computer with counter card , and special software for measurement control and data analysis , forming a digital , virtual , synthetic , automatic system for time - frequency measurement with high precision 本论文提出了一种高精度时间频率信号测量与分析平台的系统方案，该平台由两个差拍器、一台带有插卡式计数器的pc机和一个专用的测量控制与数据分析软件组成，形成一个数字化、虚拟化、综合化、自动化的高精度时间频率测量系统。
Wavelet transform , which has a multi - resolution analytic character , is a time - scale ( time - frequency ) analytic method of information . moreover , as both of its time - window and frequency - window can be changed it processes the ability of expressing local characters of information in time - frequency domain 小波变换是一种信号的时间尺度(时间频率)分析方法,它具有多分辨率分析的特点,而且在时频两域都具有表征信号局部特征的能力,是一种窗口大小固定不变但其形状可改变,时间窗和频率窗都可以改变的时频局部化分析方法。
At first some modification is made in conventional beam forming of frequency domain , namely to estimate doa by arrays outputs on compensated spacial frequency points of echoes . then the cwt is utilized to signal processing in space - frequency domain for estimation of doa , and the corresponding modification is also made . in the dissertation , the computer simulations of doa estimation for both narrow - band and wide - band echoes are given , so do the necessary comparison among several methods and crb 首先在传统的频域波束形成算法的基础上，提出对宽带信号的频率补偿，也即对宽带回波信号的各空间频率根据时间频率的差异进行相应补偿，然后对各阵元输出求和来得到方位估计；其次将连续小波变换引入到空间?频率处理中，从而完成对目标方位的估计，并进行了相应地补偿。
