def build(cls, m, wn, updater, index_over=None):
"""
Adds a mass balance to the model for the specified junctions.
Parameters
----------
m: wntr.aml.aml.aml.Model
wn: wntr.network.model.WaterNetworkModel
updater: ModelUpdater
index_over: list of str
list of pipe names; default is all pipes in wn
"""
if not hasattr(m, 'approx_hazen_williams_headloss'):
m.approx_hazen_williams_headloss = aml.ConstraintDict()
if index_over is None:
index_over = wn.pipe_name_list
for link_name in index_over:
if link_name in m.approx_hazen_williams_headloss:
del m.approx_hazen_williams_headloss[link_name]
link = wn.get_link(link_name)
f = m.flow[link_name]
status = link.status
if status == LinkStatus.Closed or link._is_isolated:
con = aml.Constraint(f)
else:
eps = 1e-5 # Need to provide an options for this
start_node_name = link.start_node_name
end_node_name = link.end_node_name
start_node = wn.get_node(start_node_name)
end_node = wn.get_node(end_node_name)
if isinstance(start_node, wntr.network.Junction):
start_h = m.head[start_node_name]
else:
start_h = m.source_head[start_node_name]
if isinstance(end_node, wntr.network.Junction):
end_h = m.head[end_node_name]
else:
end_h = m.source_head[end_node_name]
k = m.hw_resistance[link_name]
minor_k = m.minor_loss[link_name]
con = aml.Constraint(
expr=-aml.sign(f) * k * aml.abs(f)**m.hw_exp -
eps * k**0.5 * f -
aml.sign(f) * minor_k * f**m.hw_minor_exp + start_h -
end_h)
m.approx_hazen_williams_headloss[link_name] = con
updater.add(link, 'status',
approx_hazen_williams_headloss_constraint.update)
updater.add(link, '_is_isolated',
approx_hazen_williams_headloss_constraint.update)
def build(cls, m, wn, updater, index_over=None):
"""
Adds a mass balance to the model for the specified junctions.
Parameters
----------
m: wntr.aml.aml.aml.Model
wn: wntr.network.model.WaterNetworkModel
updater: ModelUpdater
index_over: list of str
list of pipe names; default is all pipes in wn
"""
if not hasattr(m, 'piecewise_hazen_williams_headloss'):
m.piecewise_hazen_williams_headloss = aml.ConstraintDict()
if index_over is None:
index_over = wn.pipe_name_list
for link_name in index_over:
if link_name in m.piecewise_hazen_williams_headloss:
del m.piecewise_hazen_williams_headloss[link_name]
link = wn.get_link(link_name)
f = m.flow[link_name]
status = link.status
if status == LinkStatus.Closed or link._is_isolated:
con = aml.Constraint(f)
else:
start_node_name = link.start_node_name
end_node_name = link.end_node_name
start_node = wn.get_node(start_node_name)
end_node = wn.get_node(end_node_name)
if isinstance(start_node, wntr.network.Junction):
start_h = m.head[start_node_name]
else:
start_h = m.source_head[start_node_name]
if isinstance(end_node, wntr.network.Junction):
end_h = m.head[end_node_name]
else:
end_h = m.source_head[end_node_name]
k = m.hw_resistance[link_name]
minor_k = m.minor_loss[link_name]
a = m.hw_a
b = m.hw_b
c = m.hw_c
d = m.hw_d
con = aml.ConditionalExpression()
con.add_condition(
aml.inequality(body=aml.abs(f),
ub=m.hw_q1), -k * m.hw_m * f -
aml.sign(f) * minor_k * f**m.hw_minor_exp + start_h -
end_h)
con.add_condition(
aml.inequality(body=aml.abs(f), ub=m.hw_q2),
-k * (a * f**3 + aml.sign(f) * b * f**2 + c * f +
aml.sign(f) * d) -
aml.sign(f) * minor_k * f**m.hw_minor_exp + start_h -
end_h)
con.add_final_expr(-aml.sign(f) * k * aml.abs(f)**m.hw_exp -
aml.sign(f) * minor_k * f**m.hw_minor_exp +
start_h - end_h)
con = aml.Constraint(con)
m.piecewise_hazen_williams_headloss[link_name] = con
updater.add(link, 'status',
piecewise_hazen_williams_headloss_constraint.update)
updater.add(link, '_is_isolated',
piecewise_hazen_williams_headloss_constraint.update)