In one preferred embodiment, {HEAD ~ an air blast} is directed through {TAIL ~ the porosity} created by tensioning the fabric to impinge upon the underlying layer of fabric 
In one preferred embodiment , { HEAD ~ an air blast } is directed through { TAIL ~ the porosity } created by tensioning the fabric to impinge upon the underlying layer of fabric
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH