自上而下模型

分析了噪声的两种模型&时域模型和频域模型；并对传输特性，依据不同的分类方法，归纳总结出了自上而下模型与自下而上模型、时域模型与频域模型、具体模型与统计模型。

Noise models in time domain and frequency are studied , and transmission characteristic models are categorized into top-down and bottom-up model , time-domain and frequency-domain model , concrete model and statistical model .

活动轮廓模型是Kass等人于1987年提出的一种人机交互式的，自上而下的轮廓提取模型。

Active Contour Model is a method interactive between human and machine brought forward by Kass in 1987 , it 's a contour extract model from top to bottom .

本文采用自上而下的子结构模型法施加裂纹体，计算了裂纹尖端的应力强度因子，计算值与应力强度因子手册中给出的理论值非常吻合，最大误差不超过6%。

Using the sub-structure model method , this work exerts the crack body to compute the stress intensity factor for different crack depths . The calculation results are extremely tallied with the academic values offered by the handbook ; the limiting error is less than 6 % .