管道导波无损检测回波信号处理方法研究

简述了导波在管道中传播的频散特性,给出了管道导波无损检测实验信号特征.对管道导波检测的回波信号首先进行Hilbert变换,然后对变换后的信号分别进行加窗函数滤波和小波变换,处理后的缺陷信号明显易于辨别.经过分析比较,结果表明了这两种组合方法用于管道导波无损检测信号处理的效果基本一样,在实际检测应用中,选取其中任一组合方法都是可行的.     

The Morale Maze: the German Army in Late 1918

The state of the German Army’s morale in 1918 is central to our understanding not only of the outcome of World War I, but also of the German Revolution and, indeed, through the pernicious ‘stab-in-the-back-myth’, on Weimar politics and the rise of the Nazis, too. This article presents new evidence from the German archives, blended with statistical analysis, to show that the morale of some units held up better than previously thought almost to the end, and thus to suggest three things. First, it proposes that some historians have placed too much reliance on English-language sources alone, such as British Army intelligence reports, which have various flaws as evidence. Second, it argues that, while historians have increasingly moved away from generalisations about German morale, this process has further to run. Third, it suggests that no single tipping point can be identified, and that morale alone does not provide a sufficient explanation for battlefield defeat. Indeed, much of the data can only be explained if the tactical realities of the war in late 1918 are clearly understood.