The forecast of economic life for torpedo based on historical cost

The economic life of torpedo is determined by the year when the average annual cost is the lowest. The average annual cost relates to the purchasing cost and the use-maintenance cost. A GM(1,1) model of the grey system theory was modified by using the experience of exponential use-maintenance cost. The original data were used as accumulated sequence to set up the use-maintenance cost model that can be used to forecast the torpedo economic life. A Kalman sequential algorithm was adopted to weaken the randomness of the data sequence. Forecast results show that this method is satisfactory.