Lecture 2: Deterministic Performance Estimation Flashcards
What is the main assumption of DPE?
The main assumption is that there is no uncertainty
What is the consequence of DPE being too optimistic?
- DPE will be too low for throughput times and work in progress
- Quite good at estimating for departure and utilization rates
What is a flow diagram?
This is a schematic drawing of movement of material, product or people
What is inter-arrival time?
This is the time between 2 subsequent arrivals of products at their entrance in the process
What is the througput time?
This is the time between moment the product is takein into production and the moment its ready
What is the arrival rate?
This is the number of products that arrive per time unit
What is the difference between the throughput time of DPE and actual times?
The throughput time of DPE will always be lower than or equal to actual average throughput time.
What is design capacity?
This refers to the theoretical maximum output of a system/process in a given period
What is effective capacity?
This is the capacity that can be expected given the product mix, scheduling methods etc.
What is a bottleneck?
This is the slowest process in a system. That what determines the speed of the entire process. Time of bottleneck is equal to cycle time
What is the departure rate?
The departure rate is the number of products that leave the system per time unit. Departure rate is determined by the speed of the bottleneck and the speed of the arrival rate.
What is the utilization rate?
This is the fraction of the available time a machine is used for production
Total operating time / Total available time
What is batching?
this means that processing is applied to multiple products at the same time
How do you calculate availability?
Availability = MTBF / (MTBF+MTTR)
with:
MTBF: Mean Time Between Failures
MTTR: Mean Time to Repair
