测试技术_(第二版)课后习题答案.doc

测试技术第1章 习题（p29）解：（1） 瞬变信号指数衰减振荡信号，其频谱具有连续性和衰减性。（2） 准周期信号，因为各简谐成分的频率比为无理数，其频谱仍具有离散性。（3） 周期信号，因为各简谐成分的频率比为无理数，其频谱具有离散性、谐波性和收敛性。解：x(t)=sin2的有效值（均方根值）： 解：周期三角波的时域数学描述如下：0t0/2-t0/21x(t)t. . . . .（1）傅里叶级数的三角函数展开：，式中由于x(t)是偶函数，是奇函数，则也是奇函数，而奇函数在上下限对称区间上的积分等于0。故0。因此，其三角函数展开式如下：(n=1, 3, 5, ） 其频谱如下图所示：0wa(w)w03w05w00ww03w05w0j (w)单边幅频谱单边相频谱（2）复指数展开式复指数与三角函数展开式之间的关系如下：c0 =a0cn =(an-jbn)/2c-n =(an+jbn)/2recn =an/2imcn =-bn/2故recn =an/2imcn =-bn/20有双边相频谱虚频谱实频谱0wrecnw03w05w0-w0-3w0-5w00wimcnw03w05w0-w0-3w0-5w0解：利用频移特性来求，具体思路如下：a/2a/2当f0fm时，频谱图会出现混叠，如下图所示。 解：卷积1-t/2tw(t)0w(t)-t1cosw0t0t由于窗函数的频谱，所以其频谱图如上图所示。解：第二章习题（p68）=解：-解：第三章习题（p90）解：ss1s2s3=80nc/mpa0.005v/nc25mm/v=10 mm/ mpap=x/s=30mm/10(mm/ mpa)=3 mpa解：ss1s2=40410-4pc/pa0.226mv/pc=9.1310-3mv/pas2=s/s1= 2.48108mv/pc解: =2s, t=150s, =2/t300100=200.35300100=399.65故温度变化范围在200.35399.65. 解：(1)则7.71104 s(2)j(w)= -arctgwt = -arctg（）= 13.62解：0.04 s，（1）当f=0.5hz时，（2）当f=1hz时，（3）当f=2hz时，解：0.0025 s则w131.5（弧度/s） 或fw/220.9 hz相位差：j(w)= -arctgwt = -arctg() = 18.20解：fn=800hz, =0.14, f=400 解：由得第五章习题（p162）解：均不能提高灵敏度，因为半桥双臂灵敏度，与供桥电压成正比，与桥臂上应变片数无关。acknowledgements my deepest gratitude goes first and foremost to professor aaa , my supervisor, for her constant encouragement and guidance. she has walked me through all the stages of the writing of this thesis. without her consistent and illuminating instruction, this thesis could not havereached its present form. second, i would like to express my heartfelt gratitude to professor aaa, who led me into the world of translation. i am also greatly indebted to the professors and teachers at the department of english: professor dddd, professor ssss, who have instructed and helped me a lot in the past two years. last my thanks would go to my beloved family for their loving considerations and great confidence in me all through these years. i also owe my sincere gratitude to my friends and my fellow classmates who gave me their help and time in listening to me and helping me work out my problems during the difficult course of the thesis. my deepest gratitude goes first and foremost to professor aaa , my supervisor, for her constant encouragement and guidance. she has walked me through all the stages of the writing of this thesis. without her consistent and illuminating instruction, this thesis could not havereached its present form. second, i would like to express my heartfelt gratitude to professor aaa, who led me into the world of translation. i am also greatly indebted to the professors and teachers at the department of english: professor dddd, professor ssss, who have instructed and helped me a lot in the past two years. last my thanks would go to my beloved family for their loving considerations and great confidence in me all through these years. i also owe my sincere gratitude to my friends and my fe