Environmental Engineering Reference
In-Depth Information
In the calculations of multiple networks, the results for the networks in the list of
EPAinpfiles.txt
file include the following parameters, discussed in Chapters 6:
1.
number of nodes and links, (
n
and
m
, respectively),
2.
number of basic loops and complex loops (
l
and
L
n
, respectively),
3.
the network grid index (
NGI
),
4.
the network connectivity factor and index (
NCF, NCI
), in all three variants,
5.
the network shape index (
NSI
), in all three variants,
6.
total network length and volume (
L
tot
and
V
tot
, respectively),
7.
total demand, both in the demand-driven mode (DD) and pressure-driven mode (PDD),
8.
minimum pressure and corresponding node ID (in DD- and PDD mode),
9.
maximum pressure and corresponding node ID (in DD- and PDD mode),
10.
the resilience index of Todini (
I
r
),
11.
the network resilience of Prasad and Park (
I
n
),
12.
the network buffer index (
NBI
) in PDD mode,
13.
the average available demand fraction (
ADF
avg
) calculated by failing individual links
consecutively,
14.
the minimum available demand fraction (
ADF
min
) and corresponding link causing the
highest loss of demand.
Some other interim results will be printed in the output file as well, such as the hydraulic
indicators of the PDD simulations used for determination of ADF-values, the number of
intentionally closed pipes, the values of some input parameters (multipliers), etc.
In the calculations of single network, the results include the following parameters discussed
in Chapter 7, which is shown in the output file for each pipe:
1.
volume -
V
j
,
2.
flow -
Q
j
,
3.
velocity -
v
j
,
4.
friction loss -
h
f,j
,
5.
hydraulic gradient -
S
j
=
h
f,j
/
L
j
,
6.
power loss -
P
j
=
ρgQ
j
h
f,j
,
7.
residence time -
T
j
=
V
j
/
Q
j
,
8.
pressure buffer -
pb
j
,
9.
unit pressure buffer -
pb
j
/
L
j
,
10.
hydraulic loss area -
hl
j
,
11.
pressure buffer index -
PBI
j
.
In cases the GA-optimisation has been bypassed, a possibility exists to adjust the demand
multiplier, both in single and multiple network simulations. A simple iterative process has
been built in the programme that attempts to eliminate the difference between the minimum
pressure in the most critical node and specified PDD threshold pressure within ten
interpolation steps. In this way, the general multiplier in EPANET will be changed rather
than the pipe diameters. This form of 'synchronised' demand optimisation has been
introduced as a result of network generation process in which the geometric properties of the
nets are not necessarily matched with reasonable level of demands causing the pressure range
that is actually useless for any viable hydraulic analysis.
All calculation results of the network diagnostics module are tabulated in a text file with
extension 'xls', which makes it easily transferable in MS Excel for further processing and
graphical representation of the results.
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