Modeling a system with advance demand lead-time information
Posted: Wednesday 17 December, 2014 - 17:29
Hi,
I am trying to figure out how to model a make-to-stock supplier operating under an order-base-stock policy.
An arrival triggers a replenishment order as well as a customer order. (See attached picture of what I am trying to model)
This is what I was able to model:
A splitter splits products from a source into a replenishment order and a customer order, the upper part of my model is the "in-process replenishment orders" part, and the lower part is the "In-process customer orders" part.
In the replenishment part, the product is delayed by a server that needs to produce the order, which then puts it into a queue named: inventory.
In the customer order part, the order waits a predetermined (and assigned as a lable in the source) LeadTime, and then enters the queue named: backorder.
The assembler puts a customer order and a replenishment order back together, and puts them in a sink.
If there is a product in the inventory queue then there is no stay time for a product in the backorder queue and vice-versa.
By recording the average stay time in both these queues i want to determine the optimal behavior of the system under different conditions.
I have two problems with my model:
1. The server in the bottom part can only delay one product at a time, so products are waiting in the queue before the server which is not right. A product needs to start his leadtime delay the moment it is split and enter the backorder queue when the leadtime is finished. So, I guess this is not the right way to model this but I can't figure out how to do it. (I tried using the funcion DelayEvents but could not find a way to make it work.)
2. The(Inventory) Queue atom starts (off course) with an initial inventory level of 0, but in order to get the base stock policy right I want to vary my initial inventory level. I also can not figure out how to do this.
Attached you can find my ED model, all help is appreciated!
I am trying to figure out how to model a make-to-stock supplier operating under an order-base-stock policy.
An arrival triggers a replenishment order as well as a customer order. (See attached picture of what I am trying to model)
This is what I was able to model:
A splitter splits products from a source into a replenishment order and a customer order, the upper part of my model is the "in-process replenishment orders" part, and the lower part is the "In-process customer orders" part.
In the replenishment part, the product is delayed by a server that needs to produce the order, which then puts it into a queue named: inventory.
In the customer order part, the order waits a predetermined (and assigned as a lable in the source) LeadTime, and then enters the queue named: backorder.
The assembler puts a customer order and a replenishment order back together, and puts them in a sink.
If there is a product in the inventory queue then there is no stay time for a product in the backorder queue and vice-versa.
By recording the average stay time in both these queues i want to determine the optimal behavior of the system under different conditions.
I have two problems with my model:
1. The server in the bottom part can only delay one product at a time, so products are waiting in the queue before the server which is not right. A product needs to start his leadtime delay the moment it is split and enter the backorder queue when the leadtime is finished. So, I guess this is not the right way to model this but I can't figure out how to do it. (I tried using the funcion DelayEvents but could not find a way to make it work.)
2. The(Inventory) Queue atom starts (off course) with an initial inventory level of 0, but in order to get the base stock policy right I want to vary my initial inventory level. I also can not figure out how to do this.
Attached you can find my ED model, all help is appreciated!