Environmental Engineering Reference
In-Depth Information
1
0.9
0.8
0.7
Ir
In
NBI
ADFavg
ADFmin
0.6
0.5
0.4
0.3
0.2
0.1
0
Figure 5.20
Comparison of I
r
, I
n
and NBI for 16 optimised nets from Figure 5.1a-d
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Figure 5.21 shows the result for networks of equalised diameters where these are clearly too
small in case of
net3
and
net4
, resulting in negative values of all three indices, and pretty
sufficient, actually too big for the looped configurations. As all the nets have the same pipe
diameters, there will obviously be no difference between the
I
r
, and
I
n
values. In case of
networks 5, 7 and 10 to 13, both indices will range between 0.7 and 0.8 for otherwise highly
reliable networks;
net12
and
net13
would have the NBI (
ADF
avg
and
ADF
min
) values of 1.0.
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
Ir
In
NBI
ADFavg
ADFmin
0.2
0.1
0
-0.1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
-0.9
Figure 5.21
Comparison of I
r
, I
n
and NBI for 16 equalised nets from Figure 5.1a-d
5.7
TEST NETWORK FROM LITERATURE
The discrepancy between the values for NBI, and
I
r
and
I
n
, which is visible in Figures 5.15,
5.17 and 5.19, raised some concerns about the correctness of calculation of the two resilience
indices in view of somewhat unclear definition of the parameter
H
*
in Equations 5.20 and
5.22 in the papers of Todini (2000) and Prasad and Park (2004). To be sure, the comparison
of all three indices was also done on the two-loop case network, shown in Figure 5.22, which
was used in both of these references. Assuming the PDD threshold of 20 mwc, the minimum
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