IS604 - Homework Week 6
Robert Sellers
March 12, 2017
Intermediate Modeling / Random Variate Generation
5.1
What is the difference between an object property and an object state?
States have the ability to be modified while a simulation is in progress. These include model entity priorities, pictures, and server buffers. These are associates with the “runspace”, as opposed to Properties which are associated with the “instance”. Generally speaking, these include initialization values.
5.2
Consider a process associated with a Server object. What is the difference between a token’s parent object and its associated object?
The token is the temporal object created during each process, with a parent and an associated object sharing information between the nodes. In the case of a model entity visiting a server, the parent object is the server and the associated object is the model entity.
5.3
Develop a queueing model that gives the steady-state values analogous to the values in Table 5.2.
Utilizing the following metrics inside the experimental design:
Placement Utilization (Pp) - Placement.Processing.Contents.AverageNumberWaiting
Inspection Utilization (Pi) - Inspection.Processing.Contents.AverageNumberWaiting
Number in system (L) - PCB.Population.NumberInSystem.Average
Time in system (W) - PCB.Population.TimeInSystem.Average
Average # of Good - GoodParts.InputBuffer.NumberEntered
Average # of Bad - BadParts.InputBuffer.NumberEntered
1
The experiment was then copied and exponetial processing times were transplanted into the model.
Placement becomes Random.Exponential(4) & Inspection becomes Random.Exponential(3).
2
5.4
The source was pegged to a Rate table, with 6 (assumed poisson) arrivals per hours between 9 and 5. Four scenarios were run on 4 different replication inputs. For development purposes, 5 replications is plenty, however upon viewing the comparative Response Results charts, we see that only 25 replications showed all metrics contained within the 95% confidence interval.
Performance metrics analyzed:
Time in system (W) - Customer.Population.TimeInSystem.Average
Reception Utilization (Pu) - Reception.Processing.Contents.AverageNumberWaiting
Vision Utilization (Pv) - Vision.Processing.Contents.AverageNumberWaiting
Written Computer Utilization 1 (Pwc1) - Written1.Processing.Contents.AverageNumberWaiting
Written Computer Utilization 2 (Pwc2) - Written2.Processing.Contents.AverageNumberWaiting
Written Computer Utilization 3 (Pwc3) - Written3.Processing.Contents.AverageNumberWaiting
Reception Queue Avg (LqR) - Reception.InputBuffer.Contents.AverageNumberWaiting
Vision Queue Avg (LqV) - Vision.InputBuffer.Contents.AverageNumberWaiting
Written Computer Queue Avg 1 (LqWC1) - Written1.InputBuffer.Contents.AverageNumberWaiting
Written Computer Queue Avg 2 (LqWC2) - Written2.InputBuffer.Contents.AverageNumberWaiting
Written Computer Queue Avg 3 (LqWC3) - Written3.InputBuffer.Contents.AverageNumberWaiting
1
5.5
The entity average walking speed was revised at 1.4 meters per second (wikipedia source). Below is a link to a youtube clip of the animation.