First , the theoretical analysis about the micro perforated absorber is present in this paper . then , the source noise of the apu of ma60 is obtained by the outside test in airport . based on the test result , a micro perforated absorber is designed and produced 论文根据微穿孔板吸声体理论和微穿孔板消声器的基本理论，对微穿孔板消声器结构参数与吸声特性之间的相互影响进行了深入的分析和探讨；建立了一套微穿孔板吸声结构的设计方法。
The result shows that there are various patterns of vessel elements and three types of perforation plates : both ends of the vessel element are simple perforation plate ; one end with simple perforation , the other with two simple perforations ; one end with two simple perforations , the other with three simple perforations 在荔枝的次生木质部中导管分子存在着多种的样式，并且导管分子穿孔板存在着3种类型：两端均为一个单穿孔板；一端一个单穿孔板另一端两个单穿孔板；一端两个单穿孔板另一端三个单穿孔板。
It was shown that vessel elements in secondary xylem of p . emblica have many different forms and most of them have tails and their perforation plates divide into two types : ( 1 ) there is one simple perforation plate at each end of the vessel elements and ( 2 ) there is one simple perforation plate at one end of the vessel elements and two simple perforation plate at the other end ; ( 3 ) a few vessel elements have special inclusions ; ( 4 ) the intervascular pits are alternate pits ; ( 5 ) the pits between the vessels and rays are mixed pits , pits with transverse gashes and scalariform pits 结果发现，余甘子次生木质部导管分子中存在着许多不同的样式，导管分子大多数具尾；其穿孔板存在着两种类型： ( 1 )两端均为1个单穿孔板； ( 2 )一端为1个单穿孔板;另一端为2个单穿孔板； ( 3 )极少数的导管分子具有特殊的内含物； ( 4 )管间纹孔式为互列纹孔式； ( 5 )导管射线间纹孔式为混合型纹孔与横列刻痕状纹孔以及梯状穿孔。
