查询词典 frequency analysis

In order to solve these problems encountered in the application of Artificial Intelligence in fault diagnosis of power transformer, some improved methods are presented, the main research work of this dissertation consists of the following parts: The conception of cumulative frequency in data reliability analysis is utilized to unify the results of Dissolved Gas Analysis. And with the application of the class-attribute function, the evaluation of typicality of samples and the selection of characteristic vectors of fault could be realized by integrating the technique of multivariate statistical analysis.

针对目前应用人工智能技术进行变压器绝缘故障诊断时所遇到的主要困难，本文进行了深入的研究与分析，进而提出了相应的解决方法，主要的研究工作如下：提出利用可靠性数据分析中累积频率的概念对油中溶解气体分析数据进行归一化处理；并在引入"类属函数"的概念后，结合多元统计分析技术实现了样本的典型性评价与故障特征矢量的选取。

In response to signals and system simulation studies, MATLAB also demonstrated its strong role, with MATLAB simulation for the time signal convolution, discrete, continuous LIT system of time-domain analysis, synthesis and periodic signal of decomposition, the bi-frequency system Domain analysis, signal modulation and demodulation, discrete systems, the Z-domain analysis.

在信号与系统仿真响应的研究中，MATLAB也体现其强大的作用，用MATLAB仿真连续时间信号的卷积计算，离散、连续LIT系统的时域分析、周期信号的合成与分解、系统的复频域分析、信号的调制与解调，还有离散系统的Z域分析。

Since wavelet function has local features both in space and frequency domains, so wavelet analysis provides a good analysis mothed for multiresolution analysis of signal and image and effectuation and reliability of mothed have been proved by the experiment.

小波理论的发展史并不很长，但是由于它具有很多良好的性质，因此它的出现对很多领域的的研究和发展有很大的促进作用。

To analyze the clinical characteristics of AS on Chinese and Western medicine,measurement data were carried out with descriptive frequency analysis and t test,enumeration data were analyzed with chi-square test,the study of TCM patterns were carried out with Pearson correlation analysis,and cluster analysis,etc.

采用Access软件建立与课题相关的数据库进行数据管理，统计分析在统计软件平台进行，计量资料进行描述性频数分析和t检验，计数资料采用卡方检验，证候学研究采用Pearson相关分析、聚类分析等。

Based on a series of signal process and noise source identification techniques, especially the major noise source identification methods, such as expurgation method, sound intensity analysis, spectrum analysis vibro-acoustic correlation analysis and so on, the pass-by noise control of SC7080A and SC6360B are studied in detail. By the roadway and dais experiments, the major noise and radiating parts are identified and some economical controlling methods are made. For the SC7080A, to control the emissing noise from the intake and shell vibration of air cleaner, a intake muffler is installed between the air cleaner and intake valve. Based on the theory of Helmholtz resonator, One three-parallel-connected resonant silencer is designed and trial-manufactured. For the SC6360B, the attenuation performance of exhaust muffler in high frequency region is improved. To reduce the vibration noise of shell part, the structure of oil sump tank, exhaust manifold shield and exhaust manifold shield are analyzed and improved. At the same time, some measures, such as sound absorption, sound insulation, are taken to reduce the noise of engine surface emissivity and a sound shield is designed.

本文首先综述了目前国内外汽车加速噪声控制的现状、主要方法和技术措施，在此基础上，结合SC7080A和SC6350B汽车的车外加速噪声水平及现状，综合运用分别运行法、声强法、频谱分析法、声振相干函数法等现代噪声源识别方法，对SC7080A和SC6360B汽车进行了准确详细的车外加速噪声源识别并提出了经济可行的控制方案，针对SC7080A，主要在空气滤清器和进气阀门之间的进气管道上加装进气消声器，抑制空气滤清器壳体表面和进气口两处的噪声辐射，根据Helmholtz共振腔原理设计了三腔并联旁支型共振消声器，并进行了工程化设计和试制；针对SC6360B，主要改善了排气消声器在高频段的消声性能，对罩壳类零件进行了结构改进，降低了其表面噪声的辐射，并对发动机舱进行了吸声、隔声处理，设计了发动机隔声罩。

Wavelet analysis is a tool of time-frequency analysis after Fourier analysis.

小波分析是继Fourier分析之后的新的时频域分析工具。

The main research contents are stated asfollow: 1. Simplified analysis method of space grids structuresDouble-layer space grids have been assumed as sandwich plate, and are analyzed bythe nontraditional theory of plate with consideration of shear deformation and threegeneralized displacements. Using the theory of energy variation, simplified methodsfor bending, stability and vibration analysis of double-layer space grids have been putforward based upon the idea of split rigidity. The formulas for calculating internalforces, displacements, critical load and natural frequency have been given out. Set thestable cables and bearing cables in hyperbolic paraboloid cable nets are all replaced bytruss-cable to form truss-cable nets structures. Natural vibration analysis method fortruss-cable nets structures has been put forward using the energy variation method andRayleigh method.

主要内容包括： 1、空间网格结构静动力简化分析方法把网架结构简化为夹层板，采用考虑剪切变形的具有三个广义位移的平板弯曲理论进行分析，基于分解刚度思想利用能量变分原理提出了网架结构弯曲、稳定与振动分析的简化计算方法，给出了位移、内力、屈曲临界荷载和固有频率的计算公式；将双曲抛物面索网中的稳定索与承重索均用劲性索代替形成劲性索网结构，基于能量变分法和Rayleigh法给出了劲性索网结构固有振动分析的简化计算公式。

The wavelet analysis belongs to the harmonic analysis, is one time domain, the frequency range analysis, has the multi- resolution characteristic, it ingeniously uses in the non- even distribution the resolution through the translation invariable window observation unstable signal.

小波分析属于调和分析，是一种时域、频域分析，具有多分辨率特性，它巧妙地利用非均匀分布上的分辨率通过平移的可变窗口观察非稳信号。

Meanwhile, this paper systematically summarized the present fractional-order control theory results distributed mostly in such aspects as continuous and discrete time domain analysis, approximated numerical analysis, common frequency domain analysis, plane locus method based on variable transposition, etc, and became an effective foundation of forming a complete control and system theory for fractional-order control systems.

同时，论文对当前国内外已有的分数阶控制理论成果进行了较为系统的整理，主要集中在连续和离散时间域分析、近似数值分析、一般复频域分析、基于变量变换的平面根轨迹分析等方面，具有综述性质，是建立一套完整的分数系统控制理论与系统理论的有效基石。

Secondly, according to the spectral correlation theory of second order cyclostationary processes, maximumlikelihood filters are used to estimate the cyclic spectra. By estimating the crossspectra of the two frequency shifted versions of cyclostationary signal, the cyclic spectra can be obtained. The analysis effective bandwidth of maximumlikelihood filters is studied in details. In case of cross-spectra estimation, the analysis effective bandwidth of maximum-likelihood filters is not correct. A new method to calculate the analysis effective bandwidth is presented.

第二，根据二阶周期平稳随机信号的谱相关理论，提出了循环谱密度估计的最大似然滤波器法，即采用最大似然滤波器估计出周期平稳信号的两个频移分量之间的互谱密度，从而得到了循环谱密度的估计；对最大似然滤波器的有效分析带宽做了详细的分析，指出了在互谱密度估计时以往的有效分析带宽不正确，并提出了互谱密度估计时的有效分析带宽的新的计算方法。

He got into race cars, while my father liked go-karts more, so I didn't really pay attention to what Diego was doing, as I was just racing karts.

叔叔开的是跑车，而我父亲更喜欢越野卡丁车，所以我并不太关注Diego在做什么，我仅仅在跑我的卡丁车而已。

She is at present gone to look for the best nectar and ambrosia to regale me this evening.

她今晚为款待我，现在又去准备美酒佳肴去了。