Martin Fishlock
12/19/2006 11:28:00 AM
Hi Deano,
This is a classic situation where you have to maximise profit with multiple
constrainsts and you need to devise a method to combine the constaints to use
the solver
Generally make a cash flow or profit and loss statement with the relevant
costs and see if you can minimise them with the given constaints.
--
Hope this helps
Martin Fishlock
Please do not forget to rate this reply.
"deano" wrote:
> Hi Martin,
>
> ok, I added a lifting cost cell and set solver to minimize this cost.
>
> if lift for the day > 0, then cost = 5 + 0.42*lift volume. Minimize 21
> day sum of lift cost.
>
> The result is same as what I had when I set solver to minimize
> frequency of lifts with =COUNTIF(J9:J29,">0") .
>
> Any clues on how to get solver to span out lifts, increase lift size to
> minimize fixed cost of 5 with each lift? Is solver the right approach
> to this problem?
>
>
> Martin Fishlock wrote:
> > You need to include the aspect of the cost of lifts and therefore minimise
> > the cost of lifts as well as the other constraints.
> > --
> > Hope this helps
> > Martin Fishlock
> > Please do not forget to rate this reply.
> >
> >
> > "deano" wrote:
> >
> > > a plant produces any 2 of 3 products (make1, make2, make3). Plant knows
> > > how much to produce over a period of time of each product. normally
> > > product 1 is set to zero. product 2 can be stored in any of three tanks
> > > (tank1, tank2, tank3). product 3 can only be stored in tank4. Tanks
> > > have minimum volumes known as heels and maximum volumes. Liftings of
> > > products (2 & 3) need to be scheduled to maintain steady production
> > > without "runout" of room. Liftings have maximum volume/lifting. Lifting
> > > frequency should be minimized to save cost.
> > >
> > > If production is known say for three weeks ahead, how best to estimate
> > > when and how much to lift during this 21 day period? how to rotate
> > > filling of tanks1,2, & 3 with product 2?
> > >
> > > solver is one approach. counting number of lifts > 0 with
> > > =COUNTIF(J9:J29,">0") , and using solver to minimize this cell still
> > > produces 21 daily lifts. How would you get solver to produce lifts
> > > every 3-4 days or so as tanks working capacity offer 4+ days of
> > > production before "runout" of room.
> > >
> > > Is there a better way to do this than solver?
> > >
> > > cheers,
> > > deano
> > >
> > >
>
>