Offshore shipbuilding industry is known for its highly customized products, which are in most cases tailor-made for specific missions. Being a traditionally conservative industry, it follows conventional design practices. Because of the urge to quickly respond to changing market situations and the need for a structured method to reuse design knowledge across different projects, modern design methodologies like modularization are of considerable interest in this industry. To implement modular thinking, it has to overcome many challenges such as non-functional engineering description of design, scaling, clustering, logistical issues, structural complexities etc. Different modular methodologies can be adopted to establish a modular product platform. Modular Function Deployment (MFDTM) is a popular theory of modularization with five distinct steps to identify the objects that should be modularized and optimize them for the whole manufacturing system. Application of MFDTM method reveals that among various spaces inside the accommodation of an OSV, crew single, crew double and officer’s cabins are the most appropriate ones to be modularized.Based on the output of MFDTM method and the vessel database from System Based Ship Design (SBSD) approach for OSVs, a decision support framework has been developed to assist the naval architect of the vessel to design the accommodation block. Standardized templates are used for arrangement of the modules. The spaces in the accommodation are categorized into three module classes. The DSF can calculate the optimum size, type and location of the modules according to design requirements and system constraints. The vessel database is used here to determine the required area for the spaces that are not standardized. The DSF is demonstrated by an illustrative example and later by a simplified real case study. A mock up of a user interface has also been developed to give an idea of user interaction with a computer tool based on the DSF. For the real case study, a small program has been developed containing some 1200+ lines of code, which can process simplified accommodation design cases.To build an effective DSS for designing the accommodation block of OSVs, standardization of spaces by modularization must be done with enough room for flexibility of design by designer intervention. This DSF exhibits the underlying logics and structure of such DSS, which can be very useful to the designers upon further development.

Given  the  necessity  to  achieve  vertical  integration  in  complex  NPD  projects,  this  study  offers  a perspective  on  the  implication  of  customers  and  suppliers  involvement  under  technological uncertainty.  The  purpose  of  this  work  is  to  use  SoSE  in  order  to  develop  a  framework  that  may support Marine system design in NPD under technological uncertainty. It has been assumed that it is possible to achieve the Pareto optimum with respect to the key variables influencing the success of the NPD process; furthermore, this study will explore the possibility to tackle the goal misalignment between Customer, Suppliers and OEMs interacting in an evolving scenario and to offer a decisional ground  for  the  mitigation  of  such  misalignment.  Concluding,  the  purpose  of  this  study  has  been expanded by answering three research questions on how Technological uncertainty influences NPD in  Marine  System  Design,  what  alternative  frameworks  can  be  used  to  structure  such  designs  and how System of Systems Engineering can be used to build such alternatives.  The structure of the model built in this report is based on the concepts related to Enterprise System of Systems Engineering (SoSE), Agency Costs and Transaction Costs theories. The analysis is based on a  case  study  where  a  propulsion  system  has  to  be  developed  in  order  to  meet  the  incumbent environmental deadline imposed by the Policy maker, while taking into account future adaptations.     Basing  on  the  results,  the  largest  misalignments  pertain  to  the  Value dimension,  where  the  actors prioritized different features depending on their different positioning of the actors in the value chain, leading to an increase of the Agency costs in the NPD. On the other hand, the possibilities to share the  knowledge,  to  split  the  costs  over  the  involved  parties  and  to  reduce  the  Transaction  costs represent  the  main  advantages  perceived  from  the  actors.  An  integrative type  of  structure  of  the collaboration  within  the  actors,  for  instance  establishing  a  Joint  venture  or  through  Integrated development, would reduce the misalignments.  Finally,  ABB  can  use  SoSE  in  order  to  manage  its  internal  R&D  process  and  the  involvement  of customers  and  suppliers.  In  general,  SoS  can  help  OEMs  in  dealing  with  uncertainty  thanks  to  the concept  of  fluid  boundaries.  As  a  consequence,  the  integrated  system  will  benefit  of  greater flexibility while complying with the requirements given by the customers and the suppliers.

Path-following is a primary task for most marine, air or space crafts, especially during autonomous operations. Research on autonomous underwater vehicles (AUV) has received large interests in the last few decades with research incentives emerging from the safe, cost-effective and practical solutions provided by their applications such as search and rescue, inspection and monitoring of pipe-lines ans sub-sea structures. This thesis presents a novel guidance system based on the popular line-of-sight (LOS) guidance law for path-following (PF) of underwater vehicles (UVs) subject to environmental disturbances. Mathematical modeling and dynamics of (UVs) is presented first. This is followed by a comprehensive literature review on guidance-based path-following control of marine vehicles, which includes revised definitions of the track-errors and more detailed illustrations of the general PF problem. A number of advances on relative equations of motion are made, which include an improved understanding of the fluid FLOW frame and expression of its motion states, an analytic method of modeling the signs of forces and moments and the proofs of passivity and boundedness of relative UV systems in 3-D. The revision in the relative equations of motion include the concept of state relativity, which is an improved understanding of relativity of motion states expressed in reference frames and is also useful in incorporating environmental disturbances. In addition, the concept of drift rate is introduced along with a revision on the angles of motion in 3-D. A switching mechanism was developed to overcome a drawback of a LOS guidance law, and the linear and nonlinear stability results of the LOS guidance laws have been provided, where distinctions are made between straight and curved PF cases. The guidance system employs the unique formulation and solution of the speed allocation problem of allocating a desired speed vector into x and y components, and the course control that employs the slip angle for desired heading for disturbance rejection. The guidance system and particularly the general course control problem has been extended to 3-D with the new definition of vertical-slip angle. The overall guidance system employing the revised relative system model, course control and speed allocation has performed well during path-following under strong ocean current and/or wave disturbances and measurement noises in both 2-D and 3-D scenarios. In 2-D and 3-D 4 degrees-of-freedom models (DOF), the common sway-underactuated and fully actuated cases are considered, and in 3-D 5-DOF model, sway and heave underactuated and fully actuated cases are considered. Stability results of the LOS guidance laws include the semi-global exponential stability (SGES) of the switching LOS guidance and enclosure-based LOS guidance for straight and curved paths, and SGES of the loolahead-based LOS guidance laws for curved paths. Feedback sliding mode and PID controllers are applied during PF providing a comparison between them, and simulations are carried out in MatLab.

Marine and coastal ecosystems are subject to diverse and increasingly intensive anthropogenic activities, making understanding cumulative effects critically important. However, accurately accounting for the cumulative effects of human impacts can be difficult, with the possibility of multiple stressors interacting and having greater impacts than expected, compounding direct and indirect effects on individuals, populations, communities and ecosystems. Assessment of multiple stressors therefore requires extensive scientific research that directly tests how single or multiple ecological components are affected by stressors, both singly and when combined, and as a consequence, cumulative effects assessments are now increasingly included in environmental assessments. Currently, there is a need to assess these at larger spatial scales, with additional research also urgently needed on the responses of ecological components, processes and functions to single and cumulative stressors. As cumulative environmental impacts could be better addressed by regional stressor effects assessments that combine methods for predicting multiple pressures on ecosystem recovery alongside degradation, this study used several separate approaches that can be used in parallel to give support for local management measures. I tested four completely different methods - a range of multi-metric indices, a food web model (Ecopath), a predictive model (Ecosim) and a Bayesian Belief Network model. Each approach was tested and compared in two shallow water estuarine systems, in Scotland and England, initially concerning the impact of nutrient enrichment and subsequent recovery and was followed by an investigation of how the addition of multiple stressors (nutrient levels, temperature and river-flow rates) would impact the future state of each system. The response to stressors was highly context dependent, varying between and within geographic locations. Overall, each of the four different approaches complemented each other and gave strong support for the need to make big reductions in the pressures and to consider trade-offs between impacting pressures. The models and tools also indicate that in order to reach an improved overall environmental state of each ecosystem, a focus on nutrient reductions are likely to be the most effective of the controls on stressors explored and that cumulative effects of the management of nutrient inputs and increased water temperatures and river-flow are likely to exist.

É descrita a modelagem, para controle, da dinâmica de uma plataforma semisubmersível com seis graus de liberdade. O modelo inclui os efeitos dos tanques de lastro como forças e momentos, assim como a dinâmica da plataforma. Os parâmetros do sistema foram obtidos das características da plataforma e de resultados experimentais obtidos com uma plataforma semisubmersível de dimensões reduzidas. O desenvolvimento de uma metodologia e de um software capazes de determinar o volume submerso e o centro de empuxo de uma estrutura com geometria complexa foram pontos determinantes nessa Dissertação, tendo em vista a complexidade do processo e as importâncias desses parâmetros para o desenvolvimento do modelo. A linearização do modelo permitiu a elaboração de uma estratégia de controle capaz de estabilizar a plataforma mesmo em condições iniciais distantes do equilíbrio. As equações que descrevem o movimento da plataforma nos graus de liberdade vertical, jogo e arfagem foram desenvolvidas. A realocação dos polos e um observador de estado foram utilizados com o objetivo de melhorar o controle do sistema. / A six degrees of freedom dynamic model for the development of ballast control systems for semisubmersible platforms is described. The model includes the effects os the ballast tanks such as weights, moments ans inertias as well as the platform dynamic. System parameters are computed from physical characteristics of the platform and from experimental results obtained with a small semisubmersible platform. The development of a methodology and software capable of determining the immersed volume and center of buoyancy of a structure with complex geometry are points, wich in this M. Sc. Dissertation, in view of the complexity of the process and importance of these parameters for model development. The linearization of the model allowed the development of a control strategy capable of stabilizing the semisubmersible platform in initial conditions far from the balance. The equations describing the motion of the platform in the vertical, roll and pitch degrees of freedom have been developed. The relocation of the poles and an observer of state were used in order to improve the control system.

É descrita a modelagem, para controle, da dinâmica de uma plataforma semisubmersível com seis graus de liberdade. O modelo inclui os efeitos dos tanques de lastro como forças e momentos, assim como a dinâmica da plataforma. Os parâmetros do sistema foram obtidos das características da plataforma e de resultados experimentais obtidos com uma plataforma semisubmersível de dimensões reduzidas. O desenvolvimento de uma metodologia e de um software capazes de determinar o volume submerso e o centro de empuxo de uma estrutura com geometria complexa foram pontos determinantes nessa Dissertação, tendo em vista a complexidade do processo e as importâncias desses parâmetros para o desenvolvimento do modelo. A linearização do modelo permitiu a elaboração de uma estratégia de controle capaz de estabilizar a plataforma mesmo em condições iniciais distantes do equilíbrio. As equações que descrevem o movimento da plataforma nos graus de liberdade vertical, jogo e arfagem foram desenvolvidas. A realocação dos polos e um observador de estado foram utilizados com o objetivo de melhorar o controle do sistema. / A six degrees of freedom dynamic model for the development of ballast control systems for semisubmersible platforms is described. The model includes the effects os the ballast tanks such as weights, moments ans inertias as well as the platform dynamic. System parameters are computed from physical characteristics of the platform and from experimental results obtained with a small semisubmersible platform. The development of a methodology and software capable of determining the immersed volume and center of buoyancy of a structure with complex geometry are points, wich in this M. Sc. Dissertation, in view of the complexity of the process and importance of these parameters for model development. The linearization of the model allowed the development of a control strategy capable of stabilizing the semisubmersible platform in initial conditions far from the balance. The equations describing the motion of the platform in the vertical, roll and pitch degrees of freedom have been developed. The relocation of the poles and an observer of state were used in order to improve the control system.