Current Work
The Current Work structure represents the model year just prior to launch. Here, the length of a model year is assumed to be 12 months. At the beginning of each model year new Current Work is introduced. Current Work takes place until the end of the model year, when all the stocks of Current Work are launched regardless of completion or testing.
New Changes Per Year
The Number of New Development Tasks Introduced per Year to the Current Work Sector. These changes are the sum of the Base Change Rate, a step input and a pulse input. One may vary the base introduction rate with either a step input or a pulse input. This varying introduction rate is used to conduct tests and experiment with policies on this system.
(127) New Changes per Yr=Base Chng Rate+step(Step Input,Step Date)+Pulse Input*pulse(Pulse Date,Pulse Width)
Units: tasks
The Number of New Development Tasks Introduced per Year. The changes are the sum of the Base Change Rate, a step input and a pulse input.
Current Tasks Awaiting Advanced Work
The tasks of New Changes Per Year are input to the Current Tasks Awaiting Advanced Work one year prior to the actual model year. This stock represents the tasks awaiting introduction into the Current Work Sector for the following model year.
Since the product development cycle time is 2 years, the advanced phase of the process takes place a year before the corresponding "New Changes Per Year" are input as current work. The corresponding Advanced Tasks are done in the Advanced Tasks Sector while the New Changes wait to be introduced as Current New Tasks. When the advanced phase is finished at the end of each model year, this stock of work is introduced into the Current Tasks Not Completed.
(108) Incr in Curr Tasks Awaiting Adv Work= IF THEN ELSE(Months to Introduction Date=12,New Changes per Yr/TIME STEP,0)
Units: tasks/Month
The Increase in Current Tasks Awaiting Advanced Work is the flow of the corresponding current work that is introduced into the advanced work sector. The product development process is a 2 year process so the advanced phase of the process takes place a year before the actual project becomes the current work.
(049) Current Tasks Awaiting Adv Work= INTEG (Incr in Curr Tasks Awaiting Adv Work-Incr in Curr Tasks, 0)
Units: tasks
The Current Tasks Awaiting Advanced Work are the tasks that await to be introduced into the Current Work Sector for the following model year. The product development process is a 2 year process so the advanced phase of the process takes place a year before the tasks are input as the current work.
Current Tasks Not Completed
At the beginning of each model year, new current work is introduced to the stock of Current Tasks Not Completed. Work is completed according to the capacity that is allocated in the Capacity Allocation Sector. When the end of the model year comes, this stock of work in testing is launched regardless of completion.
(106) Incr in Curr Tasks= IF THEN ELSE(Months to Introduction Date=12,Current Tasks Awaiting Adv Work/TIME STEP,0)
Units: tasks/Month
The Increase in Current Tasks is the introduction of the current work at the beginning of the model year.
(055) Current Tasks Not Completed= INTEG (Incr in Curr Tasks-Curr Task Completion Rate-Curr Tasks Not Comp Launched, 0)
Units: tasks
Current Development Tasks Not Yet Completed. After work is done in the Advanced Sector, the corresponding current work is introduced into the Current Sector. The outflow of this stock is the current task completion rate. And at the time of launch all the stock is emptied to be launched.
(040) Curr Tasks Not Comp Launched= IF THEN ELSE(Months to Introduction Date=12,Current Tasks Not Completed/TIME STEP,0)
Units: tasks/Month
Current Tasks Not Completed launched. At the time of launch, the stock of current tasks not completed is launched at once.
Current Tasks in Testing
Work accumulates and awaits testing when it is completed or when it is reworked. Testing of the current work occurs with an average time delay of 1 month. Passing testing depends on the Fraction of Defects in Current Testing, which is determined in the Current Defects Sector . When the end of the model year comes, this stock of work in testing is launched regardless of defects.
(030) Curr Task Completion Rate = IF THEN ELSE(Months to Introduction Date=12,0,Actual Current Task Completion Rate)
Units: tasks/Month
Current Development Task Completion Rate is the actual current change rate. The flow is turned off at the instant at launch.
(044) Curr Tasks Reworked = IF THEN ELSE(Months to Introduction Date=12,0,Actual Current Task Rework Rate)
Units: tasks/Month
Current Task Rework Completion Rate is the actual current rework rate. The flow is turned off at the instant of launch.
(053) Current Tasks in Testing= INTEG (Curr Task Completion Rate+Curr Tasks Reworked-Curr Tasks Failing Testing-Curr Tasks Passing Testing- Curr Task in Testing Launched,0)
Units: tasks
Current Development Tasks Awaiting Testing. The inflows to this stock are the current task completion rate and current tasks rework rate. The outflows are the failing test rate, passing test rate and the pulse of outflow at launch. So, the stock accumulates with work being done and decreases with work being tested and it is reset for each new model year.
(046) Curr Test ThroughPut = Current Tasks in Testing/Time to Test
Units: tasks/Month
Current Testing takes place with a constant delay of Time to Test.
(135) Time to Test = 1
Units: months
It is assumed Testing would take, on average, one month.
(032) Curr Task in Testing Launched = IF THEN ELSE(Months to Introduction Date=12,Current Tasks in Testing/TIME STEP,0)
Units: tasks/Month
Current Tasks Awaiting Testing that are Launched. On the launch date the stock of current tasks in testing is launched at once.
Current Tasks to be Reworked
Rework accumulates due to tasks failing testing. The rework completion rate is a function of the capacity available as determined in the Capacity Allocation Sector. Tasks that have been reworked are tested again in the Current Tasks in Testing.
(036) Curr Tasks Failing Testing= IF THEN ELSE(Months to Introduction Date=12,0,Fraction of Curr Tasks Defective*Curr Test ThroughPut)
Units: tasks/Month
Current Tasks Failing Testing is the fraction of current testing throughput which requires rework. The flow is turned off at the instant of launch.
(057) Current Tasks to be Reworked= INTEG (+Curr Tasks Failing Testing-Curr Tasks Reworked-Curr Tasks in Rework Launched, 0)
Units: tasks
Current Tasks Awaiting Rework. The main inflow during the current development process is the tasks failing testing. The corresponding outflow is tasks reworked. When the cycle ends the remainder of the stock is launched.
(038) Curr Tasks in Rework Launched = IF THEN ELSE(Months to Introduction Date=12,Current Tasks to be Reworked/TIME STEP,0)
Units: tasks/Month
Current Tasks Requiring Rework that are Launched. At the time of launch, all the stock is emptied.
Current Tasks Completed
This is the Current Tasks Completed which have passed testing. During the cycle, the stock accumulates with the passing of testing. When launch-time comes all the stock is emptied for launch.
(042) Curr Tasks Passing Testing= IF THEN ELSE(Months to Introduction Date=12,0, (1-Fraction of Curr Tasks Defective)*Curr Test ThroughPut)
Units: tasks/Month
Current Tasks Passing Testing is the fraction of current testing throughput that doesn't require rework. The flow is turned off at the instant at launch.
(051) Current Tasks Completed= INTEG (Curr Tasks Passing Testing-Curr Tasks Comp Launched, 0)
Units: tasks
Current Tasks Completed and Passed Testing. The stock accumulates with the passing of testing. When launch time comes all the stock is emptied.
(034) Curr Tasks Comp Launched = IF THEN ELSE(Months to Introduction Date=12,Current Tasks Completed/TIME STEP,0)
Units: tasks/Month
Current Completed Tasks that are Launched. The stock of completed tasks is emptied at the time of launch.
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