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I. PURPOSE. The purpose of the Boolean Truth Table method is to prepare a reliability mathematical model from a reliability block diagram by means of Boolean algebra. The Boolean Truth Table method is applicable to single functioned and multifunctioned systems. This method is more tedious than the conventional probability method but is useful when there is familiarity with Boolean algebra. 2. PROCEDURE. 2.1 Single functioned systems. Single functioned systems consist of equipments considered to have a single function associated with equipment performance. The single functioned system Mission Reliability diagram can take the form of equipments connected in series, parallel, series-parallel, or a complex configuration. Alternate modes of operation can be considered in single functioned system models. The single functioned system Basic Reliability diagram can only be a series configuration in which any equipments provided for redundancy or alternate modes of operation for mission success are modeled in series. The procedure for the Boolean Truth Table approach is illustrated by the following example. The Mission Reliability diagram is given as: given: c PA= 0.3 PBl * PB2 0.1 and therefore Pr = P = 0.2 C1 c2 1 - P = 0.7 A 1 - PB = 0.9 1 -P = 0.8 C The Boolean algebra approach lists all equipments in a truth table form (See Table 1002-1). The truth table has 2n entries where n is the number of equipments in the system. The table has a 1 or 0 entry in each column indicating success or failure respectively on each equipment, All possible combinations of all equipments working and failing are thus listed. The procedure Is to examine each row of the truth table and decide whether the combination of equipments working and failed yields system success(S) or fallure(F). Insert an S or F respectively in the next column in the table. For each S entry, multiply the respective probabilities for the indicated state of each equipment to yield a Ps for that entry. 1002-1 METHOD 1002 18 November 1981 Source: http://www.assistdocs.com -- Downloaded: 2013-02-25T01:45Z Check the source to verify that this is the current version before use.

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