Educing and observing the stem s secondary xylem of Sorbus pohuashanensis revealed two types of perforation plates , simple porforation plate and reticulate perforation plate .

Its perforation plates include two types,scalarform perforation plate and simple perforation plate,and the perforation of the simple perforation plate is extended.

Educing and observing the stem’s secondary xylem of Magnolia biloba revealed two type of perforation plate, simple perforation plate and scalarform perforation plate.

The type of vassle element is scalarform perforation plate.

Using transfer matrix method to analyze microperforated panel absorber s acoustic characteristic;

The possibility and the significance of replacing fibred absorption materials by fibreless materials,especially by microperforated panels,are discussed.

A calculating program of microperforated panel construction is worked out in this paper.

Acoustic properties of perforated panels closely pasted with an absorptive thin layer;

Experimental study on improving absorbing property of perforated panel;

Theoretical analysis and calculation on the acoustic properties of perforated panel absorber were described herein.