Evangelos Boulougouris

Optimization of Arrangements of Ro-Ro Passenger Ships with Genetic Algorithms

Abstract A formal multi-objective optimization procedure based on genetic algorithms is applied for the internal compartmentation of Ro-Ro ferries. Attained Subdivision Index, lane meters and steel weight are considered as object functions. Case studies for a typical Ro-Ro ferry yield realistic results and show that the optimization procedure can handle realistic design problems.

Ship-to-Ship Interaction During Overtaking Operation in Shallow Water

Hydrodynamic interaction continues to be a major contributory factor in marine casualties and hazardous incidents, in particular, in the case of overtaking operations. The situation becomes even worse when the overtaking operation occurs in shallow and narrow channels, where the interaction can cause the vessels to collide and, in one case has caused the capsizal of the smaller vessel with loss of life. The aim of this article is to propose a methodology, as well as to discuss the development of a numerical program, to predict the ship-to-ship interaction during overtaking operations in shallow water. Since the vessels involved in this study have different forward speeds, an uncoupled method will be used to solve the boundary value problem. The in-house multibody hydrodynamic interaction program MHydro, which is based on the 3D Rankine source method, is used and extended here to investigate the interactive forces and wave patterns between two ships during an overtaking operation. The calculations given in this article are compared with model test results as well as published computational fluid dynamics (CFD) calculations. Very satisfactory agreement has been obtained, which indicates that the proposed methodology and developed program are successfully validated to predict the hydrodynamic interaction between two ships advancing in confined waters. The discussions also highlight the speed effects.

Energy efficiency parametric design tool in the framework of holistic ship design optimization

Recent International Maritime Organization (IMO) decisions with respect to measures to reduce the emissions from maritime greenhouse gases (GHGs) suggest that the collaboration of all major stakeholders of shipbuilding and ship operations is required to address this complex techno-economical and highly political problem efficiently. This calls eventually for the development of proper design, operational knowledge, and assessment tools for the energy-efficient design and operation of ships, as suggested by the Second IMO GHG Study (2009). This type of coordination of the efforts of many maritime stakeholders, with often conflicting professional interests but ultimately commonly aiming at optimal ship design and operation solutions, has been addressed within a methodology developed in the EU-funded Logistics-Based (LOGBASED) Design Project (2004–2007). Based on the knowledge base developed within this project, a new parametric design software tool (PDT) has been developed by the National Technical University of Athens, Ship Design Laboratory (NTUA-SDL), for implementing an energy efficiency design and management procedure. The PDT is an integral part of an earlier developed holistic ship design optimization approach by NTUA-SDL that addresses the multi-objective ship design optimization problem. It provides Pareto-optimum solutions and a complete mapping of the design space in a comprehensive way for the final assessment and decision by all the involved stakeholders. The application of the tool to the design of a large oil tanker and alternatively to container ships is elaborated in the presented paper.

A mixed-method optimisation and simulation framework for supporting logistical decisions during offshore wind farm installations

With a typical investment in excess of £100 million for each project, the installation phase of offshore wind farms (OWFs) is an area where substantial cost-reductions can be achieved; however, to-date there have been relatively few studies exploring this. In this paper, we develop a mixed-method framework which exploits the complementary strengths of two decision-support methods: discrete-event simulation and robust optimisation. The simulation component allows developers to estimate the impact of user-defined asset selections on the likely cost and duration of the full or partial completion of the installation process. The optimisation component provides developers with an installation schedule that is robust to changes in operation durations due to weather uncertainties. The combined framework provides a decision-support tool which enhances the individual capability of both models by feedback channels between the two, and provides a mechanism to address current OWF installation projects. The combined framework, verified and validated by external experts, was applied to an installation case study to illustrate the application of the combined approach. An installation schedule was identified which accounted for seasonal uncertainties and optimised the ordering of activities.

Cost based analysis of the offshore port systems

The container sector has been growing fast since its dawn, and it has almost reached a climax in terms of handling mega containerships at existing ports. In that respect the offshore port system presented here can offer operational advantages. Furthermore, it can bring improvements to the utilisation of ultra large containerships and the enhanced energy efficiency they introduce. In this framework, this paper presents a cost analysis of the possible offshore port systems including their investment cost. This research is based on data from relevant projects and studies coupled with a number of assumptions to be presented. The results suggest that the offshore container port system can play a remarkable role to reduce energy consumption in the container shipping.Copyright

An Integrated Methodology for the Design of Ro-Ro Passenger Ships

Abstract The present paper provides a brief introduction to the holistic approach to ship design, defines the generic ship design optimization problem and demonstrates its solution by use of advanced optimization techniques. A set of software tools for the parametric design and evaluation of ROPAX vessels has been developed and linked to a multi-objective optimization software, to form an integrated ship-design methodology, facilitating the design space exploration and selection of optimal designs in a rational and efficient way, Zaraphonitis et al. (2007). The present paper focuses on the optimization of design of conventional ROPAX vessels. For an application to high-speed, twin hull vessels, see Skoupas et al. (2009).

Application of holistic ship optimization in bulkcarrier design and operation

The recent years have seen an evolution of traditional approaches in ship design. Raising fuel costs, tough and volatile market conditions, the constant societal pressure for a «green» environmental footprint combined with ever demanding international safety regulations pose a new challenge for today’s Naval Architect. As a result of this current status of shipping commercial ship design is shifting towards new approaches where holistic approaches are deemed necessary. Apart from considering all the interrelationships between the subsystems that consist the vessel, lifecycle and supply chain considerations are the key in successful and «operator-oriented» designs. The paper presents a methodology within the parametric design software CAESES® for the optimization of the basic design of a new vessel and the operation of an existing one with regards to the maximization of the efficiency, safety and competitiveness of the final design. A case study with the design optimization was undertaken based on the simulation of the anticipated operation of a vessel engaged in the supply chain of Iron Ore. The target was the minimization of costs, fuel consumptions as well as of the Energy Efficiency Operating Index (EEOI) under conditions of uncertainty.

Experimental investigation on stability of intact and damaged combatant ship in beam sea

ABSTRACT The stability of a damaged ship is influenced especially by ship motions and floodwater behaviour with their interactions. The behaviour of floodwater is highly nonlinear so that a physical experiment is one of the best ways to obtain the assessment of damaged ship behaviour. The present study investigates experimentally on the performance of an intact and damaged combatant vessel DTMB-5415 in beam waves. Ship model is moored at the bow and stern during the tests in regular waves, and damaged opening is located at the starboard midships and two compartments are flooded. It is shown that ingress and egress of floodwater and the interaction between ship behaviour and water surface effect have a significant impact on ship motions and loads acting on the ship.

Multi-criteria decision-making methodology for the selection of cargo hold coating for bulk carriers

ABSTRACT The coating of cargo holds of bulk carriers constitutes the primary source of protection of the vessel’s structure against corrosion, while at the same time ensures the proper cleanliness in the holds and thus the protection of cargoes against contamination. Therefore, it plays a significant role in the vessel’s commercial operation, trading and lifecycle, making the correct selection of the coating system very important for the shipowner. This covers the design, construction and operation of the vessel and especially the maintenance and recoating of the vessel’s cargo holds. The paper herein presents a methodology for ranking and assessing coatings in a systematic, quantitative and qualitative way, in terms of the desired merits of the ideal coating system. It demonstrates the methodology’s application using three entirely different coatings and evaluating their performance at both laboratory and full scale.

Vulnerabilities and safety assurance methods in Cyber-Physical Systems: A comprehensive review

Abstract As Cyber-Physical Systems (CPSs) are a class of systems advancing in a number of safety-critical application areas, it is crucial to ensure that they operate without causing any harm to people, environment and assets. The complexity of CPSs though, render them vulnerable and accident-prone. In this study, the sources of complexity are meticulously examined and the state-of-the-art and novel methods that are used for the safety assurance of CPSs are reviewed. Furthermore, the identified safety assurance methods are assessed for their compatibility with the technical processes during the system design phase and the methods effectiveness on addressing the different CPSs sources of complexity is investigated. Advantages and disadvantages of the different safety assurance methods are also presented. Based on the results of this review, directions for the safety enhancement of CPSs and topics for future research in the area of CPSs safety are provided.