Civil Engineering Reference
In-Depth Information
1000
800
Re Z
600
400
200
0
Im Z
−
200
−
400
−
600
−
800
−
1000
0
0.5
1
1.5
2
2.5
3
3.5
4
Frequency(kHz)
Figure 3.7
Impedance
Z
at oblique incidence (
θ
=
π
/4) for a layer of thickness
d
=
10
cm, and flow resistivity
σ
=
10 000 N m
−
4
s (see Figure 3.6; configuration 1).
1000
800
Re Z
600
400
200
0
Im Z
−
200
−
400
−
600
−
800
−
1000
0
0.5
1
1.5
2
2.5
3
3.5
4
Frequency (kHz)
Figure 3.8
π/
4
)
on the same layer of
porous material as in Figure 3.7, with an air gap of thickness
d
=
The impedance Z at oblique incidence (
θ
=
10 cm (see Figure 3.6;
configuration 2).
