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# Other Examples of Simualtion

Example 2.5: Reliability Problem.

• A machine has three different bearings that may fail in service.
• Bearing-life distribution is in Table 2.22.
• When a bearing fails, the mill stops, a repair-person is called, and a new bearing is installed.
• Cost for the bearing failures:

 downtime \$5 / minute repair-person \$15/ hour time to change the bearing 20 minutes for one bearing, 30 minutes for two, 40 minutes for three bearing cost \$16/each

• Table 2.24 shows the result of replacing only the broken bearings.
• Table 2.25 shows the result of the new policy: replace all three bearings if any one is broken.
• The net result is that the saving of the new policy is about \$865 a year.

Example 2.6: Random normal numbers.

• A squadron of bombers attempt to destroy an anmmunition depot (see Figure 2.8 on page 44)
• If a bomb lands in an area of 600 meters (horizontal) by 300 meters (vertical) away from a specified center, it is a hit. Otherwise it is a miss.
• We use two numbers to indicate the position that a bomb hits, X for horizontal and Y for vertical. Two separate normally distributed random numbers are generated, one for X and the other for Y.
• The result is shown in Table 2.26 on page 47.
• This type of simulations doesn't involve time. They are called Monte-Carlo, or static simulation.

Next: General Principles Up: Simulation Examples Previous: Simulation of Inventory Systems
Meng Xiannong 2002-10-18