Resource Capacity

[neto7912]

Hello,

I'm working on an emergency department (ED) model where I'm using both nurses and doctors as resources. At the ED, there is a 4:1 Patient to Nurse ratio, meaning that on average, a nurse takes care of 4 patients at the same time. When I was thinking about how to implement this logic on Simio, I looked at this option on the Seize step under Advanced options (you can see it on the picture I attached). I set the Units per Object to 0.25 - because I thought that every time a patient seizes a nurse, it will take out 0.25 out of 1 unit of capacity, instead of taking the whole 1, allowing for 3 other patients to seize her before she is completely busy.

However, this doesn't work, because I ran a model trace as I ran the model and the server is ignoring the seize because the "Units per object" is set to 0 (which is not, it's set to 0.25) - the exact model trace comment is:

"Ignoring resource release of type Specific 'Nurse'. The required capacity units per object '0' is not a positive quantity.".

Therefore, the model ignores the resource seize and processes the entity without the resource. Is this because this property field only works with integers? I thought of a work around by just multiplying my number of nurses by 4 to account for that, but that's not optimal. Would there be any other way of achieving this?

Thank you very much for the help!

[dsturrock]

Your guess is correct. The capacity units are integer. It will accept an expression, but the result is truncated to an integer.

You are also correct that you could model it by giving the nurse a capacity of 4 and then have each patient seizing one unit of it. Actually this approach makes sense if you think of it not as the number of nurses, but rather the number of patients a nurse can concurrently service - somewhat similar to the rider capacity of of a vehicle.

[Rebecca Obasi]

I'm dealing with a similar situation with my model. I'm trying to tell my model to seize 1 resource object for every 3 entities. How can I go about this?

[Kelmit]

I know it's been a while, but I just came across this question and I'm responding in case this can help someone else.

Depending on the problem, modeling nurses as patient capacity might not work; for example, if you need to limit both a nurse's active utilization and the nurse's patient load. Two general approaches exist:

1. Easier: Create two different resources, rename one 'NursesActive' and the other 'NursesPassive.' Set the latter to have n times the capacity of the former, where n is the patient ratio at n:1. Require simultaneous seizure of one of each type of resource when first assigning the patient, and release them separately, re-seizing the former as needed.
2. Harder: Subclass the Resource object and create states to track the patients assigned and a property to define the patient ratio. This approach enables more fine-tuning as necessary.