Investigation of the Risk Due to Unpredictable Criteria Via Fuzzy Logic Method

One of the most important factors in determining the necessity of passive defense consideration in civil project is the amount of probability of military attacks for that project. Therefore، in the risk analysis of passive defense studies، it is very important to determine between two or more civil projects which one have more probability to be attacked by military. This probability can be equal to the parameter that is known in different risk analysis methods as the probability of occurrence (O). This parameter is calculated typically quantitatively or qualitatively by making predictable criteria and by weighting them in different projects. But regardless of what analysis method has been used in determining the probability and that analysis method is based on how many of criteria، always some of the criteria remain as unpredictable issues. This paper offers a new method، based on fuzzy logic that have directly related to level of knowledge of attacker’s force (X) and can be used for calculation of probability increase of occurrence due to unpredictable criteria () in the different projects. By adding it to the value of probability of occurrence due to predictable criteria (O)، the amount of modified occurrence probability () can be calculated in the range that unpredictable criteria has great importance (very low probability range).