Warehouse/distribution centre model help

[up642494]

Hi guys I was wondering if you could help me,

I am modelling a distribution centre in which trucks bring in pallets in quantities of 4-10 with a uniform distribution i.e (Uniform 4,10). I have programmed these fine to go into a temporary storage area, however I am stuck on the next part. I have a packing process in which these pallets are loaded and sent to a sink. However what 4DS script would I use to make sure that the right number of pallets from the previous lorry are taken. For instance:

1. Lorry 1 arrives with (Uniform 4,10) and in this case arrives with 7 pallets.
2. 7 pallets are unloaded into the temporary storage area
3. The packing process 4DS script is also (Uniform 4,10), but what if the server tries to load 10 pallets and there are only 7?

Any help would be great (it should be noted that I am using the student logistics suite on Enterprise 8)

Dan Lumb (MSc Student at the University of Porstmouth, England)

[marlies]

You could check the content of the storage area when you decide about the load quantity. Something like this:

Code: Select all

max(
  4, 
  min(
    dUniform(4,10), 
    content(in(1,c))+1
  )
)

This takes the minimum of the available content of your storage (connected to input channel 1 of the server) and the result of the uniform distribution (note dUniform is a discrete uniform distribution and will return an integer).

I also added a Max around it, because the load should be at least 4.

Regards, Marlies

[up642494]

Hi Marlies,
Thanks for getting back to me so quickly. I'm still new at using the software (only been using it since october), so forgive me if I just ask a few more questions, but first I'll give you a bit more of a detailed explanation to my problem.

I'm creating a distribution centre scenario in which lorries come in (62 per day average - neg exponential), they go to 7 loading bays (I have calculated this using rough cycle time calculations) which deposit their pallets (uniform (4,10)) into a temporary unloading area and then are picked up by 5 forklift trucks (using similar cycle time calculations to the lorries). I have programmed everything upto the forklifts fine, now I decided to represent the forklifts as servers as I didnt have enough information regarding the forklifts (all I do know is that they have an loading time of 3 - 5 minutes (uniform)). It wasnt a problem programming the cycle time, however I was stuck with how to resolve the amount of pallets they picked up from the temporary store area.

I have now inputted the code into the batch 4DS script and now they system seems too efficient, the other forklifts arent even being used. Is there a more simple code which can do the following?

1. After the first delivery there will be 4-10 pallets, we dont know. But can we say write a code that says pick less than or equal to 10 pallets?
2. Then as the pallets would build up in the temporary storage area the other forklifts would be used? Say for instance forklift 1 has taken 10 pallets and there are four pallets left over, could another forklift take the remaining four pallets?

I hope this helps? Sorry if I didnt understand the script you originally sent me I am very new to this,

I have also attached a copy of my model to make things clearer. Once again thanks for all your help,

Kind Regards,

Dan Lumb

[up642494]

apologies I couldnt attach the model it failed to upload

[up642494]

Maybe just a simple code that says take no more than a maximum of ten pallets from the temporary loading bay queue, that way it would cover every scenario?

[up642494]

0<=10

Maybe this?

[up642494]

Hi,

I've just realised what I was doing wrong after all! My temporary storage area only had send to the first forklift on his input strategy! (so annoying)

Beginners error!

Hopefully the original script will work now!

Thanks again

Dan

[marlies]

Hi,

I prepared a small example model for you. It isn't as easy as you asked for, but I couldn't find another way yet..
Although I appreciate your approach using servers to keep the model as simple as possible, I decided to use the advanced transporter atom. This atom had standard functionality that you will need to model your case.

Please check the following locations in the model at the transporter atoms:
- Load Quantity of the transporters. There I check the content of the queues. When there are more then 9 (1 is already in the transporter), I set the quantity to 10, else I take the content of the queue. Note that In(2,c) is a reference to the queue atom. At the time when the load quantity is set, the queue is connected to the 2nd input channel of the transporter.
- Load restriction: the transporter should take items from the same container only (the same queue).
- Load time: if the content is 0 (before the 1st pallet is loaded) I defined the uniform loading time. The other pallets can be loaded with time 0.

At the dispatcher atom:
- I used the dispatch to transporter with maximum load strategy. This makes sure that pallets go to a loading transporter and not to another empty one.

I hope this gives you an idea how to continue. Good luck!

Regards, Marlies

[up642494]

Hi,
Thank you for making this, I will analyse the model and see if I can adapt my model better. Thanks very much for getting back to me. I'll let you know how I get on!,

Regards,

Dan Lumb