In this paper, the concept of "the average absorption coefficient" is put forward for the microperforated structures, and the transformation rule of "the average absorption coefficient" of different microperforated structures within certain band is computed and analyzed using computer.

There are some parameters that influence the multilayer microperfrated structure,which make acoustic impedance and absorption cofficient to compute complicatedly.

Based on this theoretical formula,a micro perforated absorber used to reduce ex- haust noise of flow duct was designed and was used in the noise reduction for the airplane MA60 APU.

The relations between diluent kinds,concentration of the polymer,cooling condition,additive et al and phase diagram,microstructures .

The layer structure and the microstructure of PP hollow fiber membrance were observed by SEM and TEM,and the main structure feature of microstructure of PP hollow fiber membrane used in MO was obtained.

In addition,microstructure can also change greatly with variation of calcination temperature.

The influences of coating condition and the content of pore-forming agent on the porous structure and the vapor permeation were studied.

Describes the application of computer image analyzing system with the microscope in measuring porous structures of ultra-high buming rate propellants.