Continuous Models

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Continuous Models

• Henry C. Co
• Technology and Operations Management,
• California Polytechnic and State University

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Inventory Model
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• Continuous-Review Reorder-Point Model EXCEL file
  Simulation (Inventory)

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• Demand
• C20NORMINV(RAND(),C4,C5) copy and paste
  C21C129
• Ending Inventory
• If beginning inventory demand, ending inventory
  beginning inventory - demand
• D20IF(B20C20,B20-C20,0) copy and paste onto
  D21D129
• Lost Sales
• If beginning inventory demand - beginning inventory
• E20IF(B20E21E129

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• Order Quantity
• If ending inventory is less than reorder point,
  order the quantity indicated in cell C15
• F20IF(D20F21F129
• Average Inventory Average of beginning and
  ending inventory
• Cost/Day
• Holding cost /unit/day average inventory
  H20G20C9C7 copy and paste onto H21H129
• Ordering cost, if order quantity 0.
• Lost sales cost units lost /unit lost sales

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Queuing Model
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• M/M/1 Queue
• Simulate for 140 customers Collect statistics
  after the 10th arrival.

Note typographical error in above screenshot
Interarrival time (row 4) is 1/?
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• Exponentially Distributed Arrival
• Interarrival time
• C12INT(-D4LN(RAND())) copy and paste onto
  C12C151. Note (1-r) is a random number between
  0 and 1.
• Excel function INT returns the integer part of
  the number.
• Time of Arrival Time of arrival of the
  preceding customer interarrival time.
• Exponentially Distributed Service Time
• F12INT(-D5LN(RAND())) copy and paste onto
  F12F151.

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• Waiting Time
• Customers are served FCFS
• IF the customer arrive before the preceding
  customer departed, the waiting time time of
  exit of the preceding customer its arrival
  time
• Otherwise, there is no waiting time.
• Exit Time
• Exit time arrival time waiting time service
  time.
• Time in system exit time arrival time.

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Note typographical error in above screenshot
Interarrival time (row 4) is 1/?