对测取的齿轮箱振动信号进行了离散小波变换,提取了齿轮箱螺栓拉断的故障信息.结果表明,小波变换或小波分析为判断、预防同类事故提供了一种有效的分析手段

grasp the main idea(we should adopt a sensible environmentalism) and the structure of the text(each part containing a contrast) 2)appreciate the various argumentative skills employed in the text 3master the key language points and grammatical structures in the text

At least 90 percent of UFO sightings can be identified as conventional objects, although time-consuming investigations are often necessary for such identification. The objects most often mistaken for UFOs are bright planets and stars aircraft, birds, balloons kites aerial flares, peculiar clouds, meteors and satellites. The remaining sightings most likely can be attributed to other mistaken sightings or to inaccurate reporting hoaxes or delusions although to disprove all claims made about UFOs is impossible

针对滚动轴承故障精密诊断的需要,采用小波包分析方法提取了滚动轴承故障的特征信号,通过小波包分析将高频信号分解到8个频带中,以频带能量作为识别故障的特征向量,应用RBF径向基神经网络建立了从特征向量到故障模式之间的映射,现场采集的数据分析表明,采用小波包和神经网络相结合的方法可以比较准确地识别滚动轴承的故障

Objectives Students will be able to: 1. understand the main idea(cloning is a two- edged sword) and structure of the text; 2. appreciate the writing strategies employed by the author, 3. master the key language points and grammatical structures in the text;

Text AA Friend In Need Objectives Background Discussion Structure Study Need Language Study

8.1正弦波振荡电路 8.2非正弦信号发生电路

详细推导出三测头误差分离原理用于测量工件圆度误差的数学公式;论述用滑动平均法和数字滤波法对采样数据作处理,可有效地抑制干扰信号,提高信噪比;通过对比实验证明上述方法对提高测量精度有明显效果

宗教观念的基本内容 是说明其所信仰的信 条和教义,从而形成 具有理性色彩的神学 体系。最基本最重要 的宗教观念大致可分 为三类,即灵魂观、 神灵观和神性观。而 这三种观念在不同的 宗教体系、不同的时 代和不同的地域有不 同的表现形式

矿山微震活动隐含着冲击地压趋势的信息.根据分形几何学观点研究了门头沟煤矿冲击地压发生前微震活动的时间分维特征.结果表明,冲击前微震信息的时间分维可以作为冲击地压的预测指标之一