Precisely assessing risk associated with critical and complex engineering systems operating in an environment with high amount of uncertainty is extremely difficult. Taking proper decisions to reduce risk level depends on how accurately the risks associated with the system are assessed. Risk assessment and safety modelling of complex systems were studied using various tools such as crisp sets, Bayesian belief network, fuzzy sets, classical logic and fuzzy logic. Neutrosophic set which is an extension of fuzzy set represents the real world better than fuzzy set due to the inclusion of the hesitancy component in the set. This research focuses on developing a neutrosophic logic–based model employing neutrosophic IF-THEN rules using linear trapezoidal neutrosophic number and analytical hierarchy process for qualitative and subjective analysis of human knowledge. The model is validated using an illustrative example for safety analysis of marine system.

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Travel time estimation & reliability evaluation of any means of transportation in every type of travel mode- land, rail, sea and air has been of immense interest of the researchers; primarily due to growing economic concern in the field of logistics & passenger movement. In situations like quantitative data inaccessibility or data imprecision, fuzzy set based possibilistic approach is recognized as a practical choice in obtaining the reliability estimates. This paper proposes and advocates possibilistic approach for travel time reliability computation of any type transportation vehicle under fuzzy type of data. The proposed approach is a novel way of computing the travel time & obtaining the related reliability value. Initially, the paper proposes the general methodology for travel time reliability evaluation. Individual travel time components of a transportation vehicle are considered as fuzzy; as a result, travel time is modelled as a fuzzy variable. Travel time reliability of a transportation vehicle has been defined with the help of possibilistic measures. The proposed procedure is then demonstrated with an application to marine vessel carrying the bulk. After illustration of the proposed methodology, sensitivity analysis is carried out. The paper ends with the comments on comparative features of the three cases.

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