Time value of life cycle cost for torpedo weapon system

Life cycle cost for torpedo weapon system is lasted for a long length of time, so the time value of the cost must be taken into account. Adopts triangle fuzzy number to show the interest rate and inflation rate. The convert rate from different year to benchmark year can be gained based on level sets and optimistic index, and then the cost of the torpedo weapon system in different year can be converted to the same year. This method can grasp the yardstick of how to treat the fuzzy factors and can reduce the influence of human beings.