A step towards risk-based decision support for ships – Evaluation of limit states using parallel system analysis

Abstract

hours taking into account speed and course changes, assuming stationary sea states. In principle, the calculations depend on a large amount of operational and environmental parameters, which will be known only in the statistical sense. The present paper suggests a procedure to incorporate random variables and associated uncertainties in the calculations of the outcrossing rates that are the basis for risk-based DSS. The procedure is based on parallel system analysis, and the paper derives and describes the main ideas. The concept is illustrated by an example, where the limit state of a non-linear ship response is considered. The results from the parallel system analysis are in agreement with corresponding Monte Carlo simulations. However, the computational speed of the parallel system analysis proved slower than expected.

A novel approach for navigational guidance of ships using onboard monitoring systems

“…[53], Nielsen [38], Nielsen et al [42], and Nielsen [41]. It is important to stress that the uncertainty modelling should both seek to describe the kind of uncertainties -aleatory (natural and physical) and/or epistemic (knowledge) -and to quantify the uncertainties in question (Bitner-Gregersen and Hagen [2] and Skjong et al [50]).…”

“…Concepts and procedures of risk-based DSS have recently been studied by e.g. Bitner-Gregersen and Skjong [4], Nielsen et al [42] and Nielsen [41]. The idea of risk-based DSS goes hand in hand with the general trend within the maritime transportation sector, where focus is turned towards goal-based standards that are based on probabilistic and risk-based methods, e.g.…”

Uncertainties

“…The shipping industry has tended to lag behind the offshore industry in these investigations. In the last decade also the shipping industry, as well as academia, has focused increasingly on studying sensitivity of ship load and responses to adopted uncertainties, see Bitner-Gregersen et al (2002), Hørte et al (2007), Bitner-Gregersen and Skjong (2008), Nielsen et al (2009).…”

Stochastic procedures for extreme wave load predictions – Wave bending moment in ships

“…(5.1). An alternative procedure might be the use of FORM in a nested procedure [22], in which the limit state, Eq. (4.4), is supplemented by an outer limit state: v t À nðrjYÞ ¼ 0…”