Comm 399 Mt Review
Yichuan Ding
COMM399-204, 2013 Winter Term 2
Mid-Term Review Problems Part I (Introduction + Process Analysis + Inventory Build-Up + OM Triangle)
True or False (You must explain your judgment if it is false!) 1. In any process, the flow time cannot be smaller than the cycle time. True. cycle time = time spent on the bottleneck resource, which must be smaller or equal to the flow time 2. If a process has two bottleneck resources, then they must have the same capacity rate. True. Bottleneck resource is the resource with the minimal capacity rate. So if there is more than one bottleneck resource, they must all have the minimal capacity rate and therefore their capacity rate must be equal. 3. In any process, the non-bottleneck resource always gets idled for some time. True. Because the unit load on a non-bottleneck resource has to be smaller than the unit load of the bottleneck resource, which is also the cycle time. So in each cycle, the non-bottleneck resource must have some time idled. 4. A manager of the call center wants to reduce the customer’s waiting time, then the only thing he (she) could do is to recruit more telephone operators. False. According to the OM triangle, increasing the capacity is not the only solution. The manager could also get more information about input rate and dynamically schedule the operators (capacity) to meet the variable input rate (customer arrivals). 5. The long-run average input rate cannot be smaller than the long-run average output rate; although it is possible that the short-run input rate be smaller than the short-run output rate when there is a positive inventory. True. In short time, if output rate > input rate, the rest is from the inventory. However, in the long run, the inventory is finite, so the long-run average of output cannot be larger than the long run average of the input rate. 6. From the Benihana’s lessons, we know that keeping the menu size smaller is the gold rule for running a successful restaurant.
COMM399-204, 2013 Winter Term 2
Mid-Term Review Problems Part I (Introduction + Process Analysis + Inventory Build-Up + OM Triangle)
True or False (You must explain your judgment if it is false!) 1. In any process, the flow time cannot be smaller than the cycle time. True. cycle time = time spent on the bottleneck resource, which must be smaller or equal to the flow time 2. If a process has two bottleneck resources, then they must have the same capacity rate. True. Bottleneck resource is the resource with the minimal capacity rate. So if there is more than one bottleneck resource, they must all have the minimal capacity rate and therefore their capacity rate must be equal. 3. In any process, the non-bottleneck resource always gets idled for some time. True. Because the unit load on a non-bottleneck resource has to be smaller than the unit load of the bottleneck resource, which is also the cycle time. So in each cycle, the non-bottleneck resource must have some time idled. 4. A manager of the call center wants to reduce the customer’s waiting time, then the only thing he (she) could do is to recruit more telephone operators. False. According to the OM triangle, increasing the capacity is not the only solution. The manager could also get more information about input rate and dynamically schedule the operators (capacity) to meet the variable input rate (customer arrivals). 5. The long-run average input rate cannot be smaller than the long-run average output rate; although it is possible that the short-run input rate be smaller than the short-run output rate when there is a positive inventory. True. In short time, if output rate > input rate, the rest is from the inventory. However, in the long run, the inventory is finite, so the long-run average of output cannot be larger than the long run average of the input rate. 6. From the Benihana’s lessons, we know that keeping the menu size smaller is the gold rule for running a successful restaurant.