1 2 Previous Next 22 Replies Latest reply on May 8, 2012 12:55 PM by indra budiantho Go to original post
• ###### 15. Re: Which Boxes?
hi,

i didnt go through the hole thread, but there was something written about knapsack.
May be your are interested in a knapsack solution with model clause combined with recursive subquery (pure model was too memory consupmtive):

Re: Analytic functions in Model clause

regards
• ###### 16. Re: Which Boxes?
Hello !

Can you please explain more in detail what you want to solve with the problem.

Regular Transport Problems:
Orders: Normaly a sender have some orders to distribute, with different details in the order it self.
This means you have to load on the truck / container ...
for example: Order 1 : 5 Boxes ( Type A), 8 Boxes ( Type B), 3 Boxes ( Type C) ...
than the scheduling department will combine the outstanding orders to an Load.
If it''s nesessary they will work out a loading plan for the warehouse staff to garantee that they laod in the right manner.
The sheduling department try to load the Orders in the right order for delivering, so the driver should be able to deliver in this
manner as planed from the sheduling department.

kind regards.
Logistic - deparment.
• ###### 17. Re: Which Boxes?
hi,

As said, i came to this just on the read of the first reply, where the knapsack problem was mentioned in.
But the problem you describe is not a "simple" knapsack, it's container packing, which is three dimensional. So the solutions in the thread linked to cant help in this case.

For that kind of problem some greedy approaches might be considerable to find not the best but some good solutions. One attempt could also be first to split the problem into bin-packing (2-dimensional) and add the thrid dimension afterwards.

I found also an interesting website of a commercial provider of a software for this kind of problems. It's worth a look i think.

So far i didnt understand your problem complete. You just look for an optimal packing for the boxes of one order in one trcuk/container and there is a final number of different boxes? These kind of restrictions could make it easier to come to an acceptable solution.

Anyway, this kind of problem is something that might be going beyond the scope of this forum perhaps.

regards
• ###### 18. Re: Which Boxes?
@chris227:
Yes I know its not so easy to fix it.
Our way to solve this is from the order side.
First we have to know the exact order (No of packages, dimensions, weight, delivery adresses, requested delivery date and so on,
than we can calculate how, which and in which order the boxes, pallets or what else should come on truck / container.
Than you are also able to offer an graphic loading plan for the warehouse staff to load in the right maner.

kind regards.
• ###### 19. Re: Which Boxes?
Than you are also able to offer an graphic loading plan for the warehouse staff to load in the right maner.
Might sound silly and frivolous:
Rather than tackling the problem directly it should be a lot easier to develop some kind of 3D Tetris (http://www.terminalstudio.com/tetrisarena.shtml):
- known the container
- known the order(s)
- load & go (manually as the first step)
taking care that:
- orders are not intermixed (to allow easy unloading at each destination)
- there is a uniform weight distribution (think you're loading a ship)
- etc ...
(all constraints that would further complicate already complex and demanding calculations, but could be rather easily handled by skilled humans)

Regards

Etbin
• ###### 20. Re: Which Boxes?
Etbin wrote:
Than you are also able to offer an graphic loading plan for the warehouse staff to load in the right maner.
Might sound silly and frivolous:
@etbin: Maybe in your sight of view.
But in practice you have to garantee that the goods are on the right position.
On the fork lift traktor you see in a graphical manner where to place the pallet on the truck, railwagon, ship, container, Warehouse ...
because the fork lift driver is loading hundrets of pallets in his daily workingtime,
so its important to give him all needed information where to put the pallet and where
take from, make the thinking needs of him so less as possible, that he can make so much as possible loading tasks in his working time.

In the past he get an Loadinglist with the needet informations, in a text manner(List).
In this case it was necessary to know where in the Warehouse on which position are the needed pallets and where
and on which place to put.
• ###### 21. Re: Which Boxes?
Just in case I might have been misunderstood (I didn't mean having graphic layout is frivolous):
If I had to produce a Loading Plan for a mixture of rather different sizes, weights, etc ... as a first step I wouldn't go for any calculations we talked about until now.
I'd start say Google SketchUp and draw the Loading Plan trying to take account for all account must be taken for as I'm not aware about the existence of efficient (algorithm, price vs. performance, ...) computer solutions for business use.
We've done something like that some thirty years ago (punched cards were sill used to enter data) but our situation was a simple one:
- maybe over 99 % there were standard pallets to be loaded (single size, approximately single weight, basically single type goods)
- orders were already assigned to trucks (fingers were good enough to calculate the loads)
- truck routes were determined already (we're a small country so travelling salesman problems can be taken as neglectable)
- the Loading List could be just the sequence (group by order) of warehouse locations where pallets had to be taken from (fork lift drivers knowing the locations minimized their roundtrips by themselves)
- the only trickier part was processing exceptions to the FIFO method based on to-be-used-before date as big customers weren't willing to accept goods usable for less than a certain period.
and that worked out pretty good (working discipline permittig it) facing problems on parallel loading (unbalanced proportion of number of trucks vs. number of fork lift drivers) or dealing with not-up-to-date data.

Regards

Etbin
• ###### 22. Re: Which Boxes?
correct, like tetris...
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