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Normal Distribution Tutorial (1) • Let Q be the order quantity, and Start with 0.0180 Center the ( , ) the parameters of the = 100, 0.0160 distribution over 0 normal demand distribution 0.0140 = 25. by subtracting the 0.0120 • Prob {demand is Q or lower} = 0.0100 2 mean D ~ N ( , ) 0.0080 Prob {the outcome of a standard Q = 125 0.0060 normal is z or lower}, where 0.018 0.0040 0.016 0.0020 0.014 P(D ≤ 125) - Q 0.012 0 25 50 75 100 125 150 175 200 z or Q z 0.01 = 0.008 P(Z ≤ 1) 0.006 0.004 • 0.45 Look up Prob {the outcome of a 0.002 Standard normal 0.40 0 standard normal is z or lower} in 0.35 ~ N ( 0 , 1 ) Z -100 -75 -50 -25 0 25 50 75 100 0.30 the Standard Normal Distribution Q Rescale the vertical 0.25 z Function Table, or Excel 0.20 and horizontal axes by 0.1 5 125 100 NORMSDIST function. dividing by the 0.1 0 25 0.05 standard deviation 0.00 1 3 -4 -3 -2 -1 0 1 2 3 4 z-Scale
Product-Process Matrix Low volume High Very high volume volume Commodity Many Product One of a Very low products Standard products volume kind products Process Space Project Unit Variable Generally costs shuttle too High Job shop Job shop Print shop Drift Bakery Batch Car Assembly line or Flow shop Flow shop assembly Utilization of Fixed Capital Generally Too Low Continuous flow Petroleum refining What is a Good Process? 4
With a banked schedule, minimum connect times drive turnaround times – not ground operations Ground Operations – Required Time for a Turnaround ( Carriers – 737-300) Cater Weight and Extend jetway and (15 min) Balance open door (2 min) Inside (1 min) Boarding Deplane 41-46 min (10 min) (13 min) Close door and jetway Clean cabin (1 min) (10-15 min) Close cargo Arrival door Dispatch (1 min) (2 min) (4 min) Prearrival Ramp (Outside) Fuel (10-15 min) Equipment Departure Set Up (2 Min) Ground power A/C 33-43 bin door min (3 min) Unload/load bags and cargo (20-30 min) Opportunities To Compress Ground Operations’ Turnaround Times 5
But, with a continuous schedule, ground operations drives turnaround time, and thus airplane/crew utilization Ground Operations – Required Time for a Turnaround ( Southwest – 737-300) Weight and Extend jetway and Balance Cater open door (1-2 min) Inside (13-16 min) (<1 min) Deplane Cleaning 21-31 min (2-5 min) (6 min) Boarding Close door (9-13 min) and jetway (<1 min) Close cargo Arrival door (<1 min) (2-7 min) Prearrival Ramp (Outside) Unload/load bags and cargo (18-21 min) Equipment Departure Set Up (1-2 Min) Ground power A/C Fuel bin door (6-11 min) 23-32 (<2 min) min The LCCs Have Engineered Rapid Turnaround Processes emulated on short haul routes by network carriers 6
What information do unit loads give us? Now, suppose the work is redistributed among the four workers as follows: Task A (5 min) Task B (5 min) Task C (5 min) Task D (5 min) Worker 1 Worker 2 Worker 3 Worker 4 • Unit Load (for each worker) = 5 min • Capacity rate for each worker = 12 units/hour • Capacity rate for the resource pool = 12 units/hour 7
Average Inventory Average inventory depends on Under the discrete whether inventory is assumed assumption: to change in discrete steps, or continuously The average inventory over weeks 0 to 3 is 300 I(t) 400 Under the continuous Under the continuous assumption: assumption: 200 The average inventory? The average inventory? ?????? “Area under the curve/3” 2 3 Week 0 1 8
Near-shoring affects airlines in several ways; domestic gains relative to international, yields go down as domestic markets are more competitive
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