Abstract :
This paper explains the optimal selection methods using nomographs to solve two essentially different problems. The one is the problem of unit level, and the other is the one of system level. The unit level assumes that the cost information as a function of failure rate ¿ and repair rate ¿ are empirically known. The paper presents a method, by which a nomograph is used to select easily the optimum pair from the infinitely many pairs (¿, ¿) of feasible solutions, to gain the required unit availability at minimum cost of this assumption. At the system level, the system is composed of n serial i-units which are selectable from a group provided for each i-unit (i = 1, 2, ..., n), several different repair plans are available for the unit. Each unit has a specific failure rate and associated cost, and each repair plan has a specific repair rate and associated cost. There are service personnel for each unit. The failure and repair rates are constant. The paper presents: 1) A method using nomographs to select the optimum pairs from the many pairs (¿i, ¿i) (i = 1, 2, ..., n) of feasible solutions, to gain the required system availability at the minimum system cost, 2) A method to select the optimum pairs, from the many pairs (¿i, ¿i (i = 1, 2, .
