Question relating to queues / delays / waiting
Posted: Tue Apr 28, 2020 8:56 pm
Hi, I am new to Vensim / SD (have currently have access to PLE / PLE+), I have looked through the manual/tutorials, however many of the functions are not available in PLE+ so I am unable to become familiar with the functionality. Is the following possible in Vensim PLE+ or Pro, Ventity (trial version).
The particular element of the modelling I am struggling with is around capacity and duration of stay with results in a backlog / waiting.
we have a number of units/people entering a system each day and a fixed capacity/number of beds. However, I would like to extend the duration (days) each set of units/person occupies a bed.
For example:
Day 1) 2 people (group a) enter the system and occupy the 2 available beds, They will remain the the beds for 2 days.
Day 2) 3 People (group b) enter the system and are unable to move into a bed (occupied by group a) so have to wait.
Day 3) 2 People arrive (group c). group a exit the system and 2 members of (group b + c combined) move into the 2 available beds and the 3 remaining members of group b + c wait.
The process continues.
I have been going over this for days now, I am able to model the flow and capacity and I have tried a number of functions/methods including Step, IfThenElse to reduce capacity to zero when the bed is occupied and Delay Fixed however when using delayed fixed it moves the whole group (when output limited by capacity) and not delaying each group entering the beds by the by the number of selected days. So far I have been unable to find a solution and would really appreciate any input.
thank you
Paul
The particular element of the modelling I am struggling with is around capacity and duration of stay with results in a backlog / waiting.
we have a number of units/people entering a system each day and a fixed capacity/number of beds. However, I would like to extend the duration (days) each set of units/person occupies a bed.
For example:
Day 1) 2 people (group a) enter the system and occupy the 2 available beds, They will remain the the beds for 2 days.
Day 2) 3 People (group b) enter the system and are unable to move into a bed (occupied by group a) so have to wait.
Day 3) 2 People arrive (group c). group a exit the system and 2 members of (group b + c combined) move into the 2 available beds and the 3 remaining members of group b + c wait.
The process continues.
I have been going over this for days now, I am able to model the flow and capacity and I have tried a number of functions/methods including Step, IfThenElse to reduce capacity to zero when the bed is occupied and Delay Fixed however when using delayed fixed it moves the whole group (when output limited by capacity) and not delaying each group entering the beds by the by the number of selected days. So far I have been unable to find a solution and would really appreciate any input.
thank you
Paul