def block_coefficient(lpp, br, draft, vol, Cb, s):
"""
lpp : length between perpendiculars or wL length
br : some breadth (e.g. breadth at the waterline)
draft : draft
vol : volumetric displacement/water weight
Vol/(Lwl*Bwl*Draft) = Cb
"""
c1 = lp.Variable('c1')
c2 = lp.Variable('c2')
state = copy.copy(s)
state.values[c1] = None
state.values[c2] = None
goal = lp.Goal.both(
lp.Goal.both(lp.Goal.mulo(lpp, br, c1), lp.Goal.mulo(c1, draft, c2)),
lp.Goal.divo(vol, c2, Cb))
state = goal(goal(goal(state)[0])[0])[
0] #forward chaining! maybe decorate or otherwise move outside
del (state.values[c1])
del (state.values[c2])
dkeys = []
for key in state.values:
if not isinstance(key, lp.Variable):
dkeys.append(key)
for key in dkeys:
del (state.values[key])
return state #s
def midship_coefficient(self):
"""
Amsh : Midship area
Dsmax : Draft at station of max section area
Cmidshp : Midship Coefficient
Amsh/(Bwl*Dsmax) = Cmidshp
"""
bwl = self.bwl
dsmax = self.dsmax
Amsh = self.Amsh
Cmidshp = self.Cmidshp
s = self.state
c1 = lp.Variable('c1')
state = copy.copy(s)
state.values[c1] = None
goal = lp.Goal.both(lp.Goal.mulo(dsmax, bwl, c1),
lp.Goal.divo(Amsh, c1, Cmidshp))
state = goal(goal(state)[0])[0]
del (state.values[c1])
dkeys = []
for key in state.values:
if not isinstance(key, lp.Variable):
dkeys.append(key)
for key in dkeys:
del (state.values[key])
return state
def waterplane_coefficient(self):
"""
Awp : wateplane area
lwl : waterline length
bwl : waterline breadth
Cwp : waterplane coefficient
Awp/(Lwl*Bwl) = Cwp
"""
lwl = self.lwl
bwl = self.bwl
Awp = self.Awp
Cwp = self.Cwp
s = self.state
c1 = lp.Variable('c1')
state = copy.copy(s)
state.values[c1] = None
goal = lp.Goal.both(lp.Goal.mulo(lwl, bwl, c1),
lp.Goal.divo(Awp, c1, Cwp))
state = goal(goal(state)[0])[0]
del (state.values[c1])
dkeys = []
for key in state.values:
if not isinstance(key, lp.Variable):
dkeys.append(key)
for key in dkeys:
del (state.values[key])
return state
def _setup_(self):
self._draft = lp.Variable('draft')
self._dsmax = lp.Variable('dsmax')
self._vol = lp.Variable('vol')
self._Cb = lp.Variable('Cb')
self._lwl = lp.Variable('lwl')
self._bwl = lp.Variable('bwl')
self._Awp = lp.Variable('Awp') #waterplane area
self._Cwp = lp.Variable('Cwp')
self._Amsh = lp.Variable(
'Amsh') #Area midship - area of largest midship section
self._Cmidshp = lp.Variable('Cmidshp') #midship coeff
self._Cp = lp.Variable('Cp')
s = lp.State(
values={
self._draft: None,
self._dsmax: None,
self._vol: None,
self._Cb: None,
self._lwl: None,
self._bwl: None,
self._Awp: None,
self._Amsh: None,
self._Cwp: None,
self._Cmidshp: None,
self._Cp: None
})
return s
Cmidshp = self.Cmidshp
Cp = self.Cp
s = self.state
print Cb, s.value_of(Cb)
print Cmidshp, s.value_of(Cmidshp)
goal = lp.Goal.divo(Cb, Cmidshp, Cp)
s = goal(s)[0]
s = block_coefficient(lwl, bwl, draft, vol, Cb, s)
s = midship_coefficient(bwl, dsmax, Amsh, Cmidshp, s)
return s
if __name__ == '__main__':
draft = lp.Variable('draft')
dsmax = lp.Variable('dsmax')
vol = lp.Variable('vol')
Cb = lp.Variable('Cb')
lwl = lp.Variable('lwl')
bwl = lp.Variable('bwl')
Awp = lp.Variable('Awp') #waterplane area
Cwp = lp.Variable('Cwp')
Amsh = lp.Variable('Amsh') #Area midship - area of largest midship section
Cmidshp = lp.Variable('Cmidshp') #midship coeff
Cp = lp.Variable('Cp')
