Learning-based ship design optimization approach

With the development of computer applications in ship design, optimization, as a powerful approach, has been widely used in the design and analysis process. However, the running time, which often varies from several weeks to months in the current computing environment, has been a bottleneck problem for optimization applications, particularly in the structural design of ships. To speed up the optimization process and adjust the complex design environment, ship designers usually rely on their personal experience to assist the design work. However, traditional experience, which largely depends on the designer’s personal skills, often makes the design quality very sensitive to the experience and decreases the robustness of the final design. This paper proposes a new machine-learning-based ship design optimization approach, which uses machine learning as an effective tool to give direction to optimization and improves the adaptability of optimization to the dynamic design environment. The natural human learning process is introduced into the optimization procedure to improve the efficiency of the algorithm. Q-learning, as an approach of reinforcement learning, is utilized to realize the learning function in the optimization process. The multi-objective particle swarm optimization method, multiagent system, and CAE software are used to build an integrated optimization system. A bulk carrier structural design optimization was performed as a case study to evaluate the suitability of this method for real-world application

Risk assessment for the installation and maintenance activities of a low-speed tidal energy converter

The study presented in this paper, is part of the Deep Green project, which includes the development of a power converter/device for employment in low-speed tidal currents. It mainly focuses on the initial steps to investigate the ways on how to minimize the risks during handling, operation and maintenance (O&M) activities of the full-scale device particularly in offshore operations. As a first tep, the full-scale device offshore installation and O&M tasks are considered. The overall risk analysis and decision making methodology is presented including the Hazard Identification (HAZID) approach which is complemented with a risk matrix for various consequence categories including personnel Safety (S), Environmental impact (E), Asset integrity (A) and Operation (O). In this way, all the major risks involved in the mentioned activities are identified and actions to prevent or mitigate them are presented. The results of the HAZID analysis are also demonstrated. Finally, the last section of this paper presents the discussion, conclusions and future actions for the above-mentioned activities regarding the full-scale device

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A Ferry Design for the Eastern Mediterranean

This thesis studies the design of passenger and vehicle ferries and prepares a preliminary design for a passenger and vehicle ferry for the route between Turkey and Italy serving the ports of Izmir and Trieste. The design allows a convenient weekly schedule for the round voyage on a long route over the complete year where seasonal differences will exist in the expected cargo. Background information on the route and consideration of existing ferries determined the carrying capacity and the cargo mix among passengers, cars and commercial vehicles. Particu lar attention is given to subdivision and damaged stability. The calculation is carried out by both the deterministic and by the probabilistic methods and consideration is given to the relative value of these methods in ensuring safety. Different arrangements of vehicle decks are examined and the relative advantages of longitudinal and transverse framing are explored by classification society and direct calculation. The economic analysis is carried out using Western European capital costs and Turkish operating costs. Income estimates are adjusted to suit the expected trading pattern. The safety of Ro-Ro vessels and further design studies are considered

On the importance of antifouling coatings regarding ship resistance and powering

This paper aims to introduce one of the latest investigations on development of marine antifouling coatings and also to demonstrate the importance of the type of antifouling coatings on fouling accumulation and ship resistance/powering. First, marine biofouling and fouling prevention methods are reviewed. A recent research study (EU FP7 FOUL-X-SPEL Project) concerning a novel and environmentally friendly antifouling coating is presented and discussed. Next, a case study is carried out to assess the effect of fouling on ship resistance and powering. A vessel is selected and the roughness on the hull surface induced by different level of fouling is considered. The increase in frictional resistance and effective power is evaluated for each particular case by using boundary layer similarity law analysis and experimental data. The results emphasise that the type of antifouling coatings has a great importance on the amount of fouling accumulation, hence on ship performance especially in low speed

Modeling of vessel and equipment cost for the maintenance activities of an offshore tidal energy array

Tidal energy is one of the most promising sectors of energy conversion that can be extracted from renewable sources, taking into account the uninterrupted flow of tidal currents regardless of the surrounding environmental conditions. In this case, a detailed analysis of the planned and unplanned maintenance attributes has been developed in order to examine the various O&M parameters influencing the cost elements. Major features for both planned and unplanned maintenance include the identification of the transportation, labor, workshop and equipment/tools cost. The above are estimated for different operational scenarios as well as for the maintenance of a single device per day. Overall, the O&M cost per device is estimated as well as the cost per MW (gross and net) and the cost/kWhr. The results show that the overall O&M cost is not prohibitive compared to other renewable energy applications while it may vary according to the initially selected O&M scenario

The effect of increasing the thickness of the ship’s structural members on the Generalised Life Cycle Maintenance Cost (GLCMC)

In the context of the EU funded IMPROVE project, the research work of a Generalised Life Cycle Maintenance Cost (GLCMC) was initiated in order to investigate the influence of a weight oriented ship structural design on its production and operational characteristics. Following this, an increase in the structural scantlings of the ship was examined following the IACS Common Structural Rules (CSR) for double hull oil tankers. A case study for a Chemical tanker is shown considering an addition in its bottom plate thickness and three different cases of mean annual corrosion rates applied. A comparison regarding the “Gross gains”, “Gross expenses” and “Net gains” for this ship is also presented. Moreover, an evaluation of the extra cost for the additional steel weight used is shown together with the outcome on the repair-free operation of the ship for different additional plate thickness. Finally, a sensitivity analysis is carried out for the most likely case (“Case 2”) and the variation of different amount of days spent in the ship repair yard

A new resilient risk management model for offshore wind turbine maintenance

The objective of this study is to implement the principles of Resilience Engineering (RE) for the maintenance management of Offshore Wind Turbine (OWT) systems by taking into account human and organizational factors. Resilience concepts are integrated into existing maintenance management elements and a resilient model is developed and applied to OWT in order to manage the maintenance related risks. The four main capabilities proposed by RE, i.e. responding, monitoring, anticipating and learning, are linked to a three level resilience system in order to prevent or mitigate OWT maintenance failures. The paper presents the applicability and effectiveness of RE in preventing accidents/incidents and system failures, and learning activities

Seafarers’ current awareness, knowledge, motivation and ideas towards Low Carbon – Energy Efficient operations

Worldwide there is increasing concern regarding green house gases, in particular carbon emissions and their detrimental effects to our earth’s atmosphere; resulting in climate change. International and National pressure requires the shipping industry to play its’ role in reducing the 3.3% of total global carbon emission that it currently emits into the atmosphere. On the 1st January 2013 the IMO are expected to enforce mandatory measures to reduce shipping carbon emissions and these measures will directly and indirectly affect the daily operations of seafarers, onshore performance staff, and managerial personnel with influence over operational procedures. It is therefore imperative that these personnel have the awareness, knowledge, skills, and motivation necessary to successfully implement the operational changes that are needed. A questionnaire has been distributed to investigate seafarers’ and onshore personnels current levels of awareness, knowledge and motivation towards carbon emissions in general and towards shipping carbon emissions. The questionnaire also asked participants to contribute which level of personnel have the most influence over carbon changes and what are the most important operational improvements that can be made. 317 questionnaire responses were collected in total and the analysis of the results is discussed within this paper. The primary benefit of this study has been to support the development of a specific Low Carbon – Energy Efficiency maritime education and training program, by identifying target group needs and attitudes, and key areas for focus

Full-scale unsteady RANS simulations of vertical ship motions in shallow water

The seakeeping behaviour of a vessel in shallow water differs significantly from its behaviour in deep water. In shallow water, a vessel’s motion responses to incident waves will be affected by hydrodynamic effects caused by the presence of a finite depth. Given that a vessel will sail in shallow water at various times during its service life, such as when entering harbours, it is important to have an understanding of the influence of shallow water on ship motions. In this study, using a commercial unsteady Reynolds-Averaged Navier-Stokes solver, a numerical study of ship motions in shallow water was carried out. Firstly, the characteristics of shallow water waves were investigated by conducting a series of simulations. Then, a full-scale large tanker model was used as a case study to predict its heave and pitch responses to head waves at various water depths, covering a range of wave frequencies at zero speed. The motion results obtained were validated against related experimental studies available in the literature, and were also compared to those from 3-D potential theory. The results were found to be in good agreement with the experimental data. Finally, it was shown that vertical motions were significantly affected by shallow water