In this study, a useful solution is proposed for assessing the safety of the ship's hull damaged by grounding in Northern Sea Route (NSR) or Arctic sea. In particular, the residual ultimate longitudinal strength of grounding damaged ship can be predicted by the grounding damage index (GDI) concept. Due to the global warming effects, the Arctic glaciers have been gradually melting, and it may bring us the new North Pole routes. However, there are uncertainties on many causes that can cause grounding accident of the commercial vessels. In this regard, residual ultimate longitudinal strength of grounding damaged commercial ship in Arctic sea is investigated. Five (5) temperatures: room temperature (RT), −20°C, −40°C, −60°C and −80°C were adopted to consider the cold temperature effect in NSR. The Panamax class oil tanker was selected for the investigation of residual ultimate longitudinal strength of grounding damaged ship. Fifty (50) reliable damage scenarios were adopted for the evaluation of structural health by utilising Residual strength versus GDI (R-D) diagram method. From this study, a modified R-D diagram is proposed which can consider grounding damage with cold temperature effect. The obtained outcome will be useful for assessing the safety of the grounded ships in Arctic sea region by measuring the grounding damage amount and surrounding air temperature [Q1].
Since the attribute of wave energy transmission is susceptible to lateral separation (S/D) between twin pontoons of floating breakwater (TPFB), arbitrarily selection of S/D may present problems in the evaluations on the effectiveness of the structure. This paper presents a numerical optimization modelling aimed at obtaining the optimum S/D through Genetic Algorithm (GA) approach. The artificial intelligence is primarily employed to minimize transmission of wave energy coefficients ( ) whereas maximize energy dissipation coefficient ( ). To achieve such demand, a numerical simulation implementing a MATLAB code as an interface between the Genetic Algorithm and a CFD program is applied. Several parameters for the effects of various wavelengths and ratios of S/D including a set of criteria have been considered in the simulation, where the optimum solution is chosen from various populations. The results demonstrated that the current GA analysis is efficient that can search a global trade-off between and to determine an optimum S/D ratio. For S/D equal to 2.72, minimized to less than 0.3 as compared to existing model ( > 0.5) while maximized to greater than 0.95 resulting to optimum hydrodynamic effects of TPFB. Hence, the optimization algorithm can serve as a useful engineering tool for a conceptual design to determine an optimum S/D for twin pontoon floating breakwater.
Attenuating waves by simple prismatic structures are increasingly recognised for coastal protection. Yet, evaluating their performance as good attenuators inevitably requires a reliable approach to adequately capture the dynamic interaction between waves and structure. This paper presents a prediction on hydrodynamic properties of pile-restrained cylindrical floating breakwater using computational fluid dynamics (CFD) approach. Several parameters for the effects of relative width (/) and relative draft (/) of the floating breakwater on the coefficient of transmission, reflection, and energy dissipation have been simulated using Flow3D. A wave boundary is assigned to give an insight into the regular and random wave effects to the parameters used in the simulation. The result revealed that the wave absorbing effect of CFB is apparently good, especially in high regular waves that considerably suppress the wave transmission. The higher energy dissipation than reflection characteristics suggests that the breakwater behaves effective as wave dissipator, especially for short waves. This attributed to the stiffness effect and in-plane damping across the vertical cage. From the practical views, the installation of the breakwater system into floating bridge or docks with limited rolls is satisfactory for perimeter protection specifically in the coastal zone of peninsular Malaysia.
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