Midterm Exam Notes

# Midterm Exam Notes - Flow Time Analysis Average Actual Flow...

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Flow Time Analysis Average Actual Flow time : avg. of actual times that units spend in the system from entry to exit =avg. actual processing time + average actual wait time Computing Actual Flow Time Direct method: -take a random sample of flow units over a period of time and measure flow time from entry to exit, then compute average Indirect method: -observe the process over a period -at different times during this period, measure total inventory (I) in the process and throughput rate (R) (inflow rate) -use Little’s Law: T= I/R Theoretical Flow Time: time in the system for a flow unit if it does not experience any wait time Aka the Total Work Content across the longest path of the process steps network =total activity time in the process for a unit excluding waiting time Computing Theoretical Process Flow Time -compute work content of all activities=activity time x 1+Rework% -compute total work content of each route -basic process flow time=total work content along longest route Process Bottleneck and Capacity Calculations Throughput (Average Flow Rate) : average number of flow units passing through the process per unit of time i.e. customers served per hour Process Capacity ( throughput) : maximum sustainable flow rate of a process -overall process capacity is determined by the “bottleneck resource” in the process Unit load of a resource: total workload needed by one flow unit from a resource

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=sum of the work contents of all activities performed on a flow unit utilizing this specific resource i.e. cashier taking an order time=2 min, order giving time=1min, unit load= 3 min Load batching Number of flow units served concurrently by one resource unit -an oven baking 12 cookies has load batching of 12 cookies -effects average flow time, throughput, process capacity Theoretical Process Capacity = (# of resource units in the resource pool x load batch x scheduled availability)/unit load Aka the capacity of the bottleneck resource, or the resource with the smallest capacity
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## This note was uploaded on 07/02/2011 for the course MGSC 485 taught by Professor Ahire during the Spring '10 term at South Carolina.

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Midterm Exam Notes - Flow Time Analysis Average Actual Flow...

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