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1
Abujaafar, Khalifa Mohamed. "Quantitative human reliability assessment in marine engineering operations." Thesis, Liverpool John Moores University, 2012. http://researchonline.ljmu.ac.uk/6115/.
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Marine engineering operations rely substantially on high degrees of automation and supervisory control. This brings new opportunities as well as the threat of erroneous human actions, which account for 80-90% of marine incidents and accidents. In this respect, shipping environments are extremely vulnerable. As a result, decision makers and stakeholders have zero tolerance for accidents and environmental damage, and require high transparency on safety issues. The aim of this research is to develop a novel quantitative Human Reliability Assessment (HRA) methodology using the Cognitive Reliability and Error Analysis Method (CREAM) in the maritime industry. This work will facilitate risk assessment of human action and its applications in marine engineering operations. The CREAM model demonstrates the dynamic impact of a context on human performance reliability through Contextual Control Model controlling modes (COCOM-CMs). CREAM human action analysis can be carried out through the core functionality of a method, a classification scheme and a cognitive model. However, CREAM has exposed certain practical limitations in its applications especially in the maritime industry, including the large interval presentation of Human Failure Probability (HFP) values and the lack of organisational factors in its classification scheme. All of these limitations stimulate the development of advanced techniques in CREAM as well as illustrate the significant gap between industrial needs and academic research. To address the above need, four phases of research study are proposed. In the first phase, the adequacy of organisation, one of the key Common Performance Conditions (CPCs) in CREAM, is expanded by identifying the associated Performance Influencing Factors (PIFs) and sub-PIFs in a Bayesian Network (BN) for realising the rational quantification of its assessment. In the second phase, the uncertainty treatment methods' BN, Fuzzy Rule Base (FRB) , Fuzzy Set (FS) theory are used to develop new models and techniques' that enable users to quantify HFP and facilitate the identification of possible initiating events or root causes of erroneous human action in marine engineering operations. In the third phase, the uncertainty treatment method's Evidential Reasoning (ER) is used in correlation with the second phase's developed new models and techniques to produce the solutions to conducting quantitative HRA in conditions in which data is unavailable, incomplete or ill-defined. In the fourth phase, the CREAM's prospective assessment and retrospective analysis models are integrated by using the established Multiple Criteria Decision Making (MCDM) method based on, the combination of Analytical Hierarchical Process (AHP), entropy analysis and Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS). These enable Decision Makers (DMs) to select the best developed Risk Control Option (RCO) in reducing HFP values. The developed methodology addresses human actions in marine engineering operations with the significant potential of reducing HFP, promoting safety culture and facilitating the current Safety Management System (SMS) and maritime regulative frameworks. Consequently, the resilience of marine engineering operations can be further strengthened and appreciated by industrial stakeholders through addressing the requirements of more safety management attention at all levels. Finally, several real case studies are investigated to show end users tangible benefits of the developed models, such as the reduction of the HFPs and optimisation of risk control resources, while validating the algorithms, models, and methods developed in this thesis.
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Townsend, Nicholas Charles. "Influencing and influences of marine vessel motions." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/207697/.
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With the aim of understanding and improving the sea keeping performance of marine craft the research addresses methods of influencing the motions of marine craft by stabilisation mechanisms, and identifying the influences on RIB motions. The two research projects, that attracted industrial support, represent two separate industrial interests concerned with influencing and understanding the influences on the sea keeping performance of marine craft. The first project, focused on developing a motion control system, for motion reduction and/or control of marine structures operating in the free-surface. The aim was to develop a system that would replace, eliminate or complement the use of current devices, in order to improve passenger comfort, overcoming the drawbacks of external hydrodynamic based systems. The research developed a new motion control system and theoretical and physical experimental studies were conducted. The second project, focused on identifying the influence of a RIB tube and the properties of the tube, on the dynamic motions of a RIB, including the effect of the motions on the occupants. Theoretical and experimental studies at full and model scale were conducted.
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Mendonça, Sandro. "The evolution of new combinations : drivers of British maritime engineering competitiveness during the nineteenth century." Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/39708/.
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This work is an attempt to explore early British steamship innovation during the 19th century from the point of view of innovation studies. The proposed analytical framework draws on neo-Schumpeterian and evolutionary economics for understanding the patterns and factors behind the phenomenon of technical change in the capital good under analysis. The thesis aims at filling a gap in the maritime economic and technological history literature, namely the issues connected to the process through which modern (mechanically-propelled, iron-hulled, screw-driven) ocean transportation emerged. Two inter-related research questions are addressed: how and why did steamships evolve in the course of the 19th century? In other words, the present research focuses on describing the dynamics of technological evolution and on identifying the key drivers of those developments. While the thesis includes a review of the relevant literature (Part I), the main work consists of original empirical research (Parts II and III). The bulk of this work primarily rests on the compilation of two new main bodies of quantitative and qualitative evidence. First, a previously unpublished dataset on the population and characteristics of steamers is used to measure the rate and direction of technical change in steamers. Second, previously unpublished archival material is used to reconstruct the innovation processes of marine engineers and naval architects and the civil society arrangements around them. The results suggest a number of stylised facts and institutional variables that have been subject to little discussion in the extant literature. On one hand, time-series and other statistical analyses suggest a technological “take-off” of steamship performance by the mid-19th century. This turning point, which was the outcome of a complex but rapid process of structural reconfiguration (the transition from wood-paddle to iron-screw as the new “dominant design”), occurred between the late 1830s and the late 1840s particularly among cargo traders and unsubsidised packets. On the other hand, documentary evidence shows that such technological breakthroughs were preceded and supported by a specific set of institutional innovations. These included the emergence of voluntary engineering associations, technical mass media and a not-for-profit ship classification society within the British national system of innovation. The thesis argues that the process of revolutionary technological innovation leading to the economically efficient long-haul merchant steamer cannot be separated from the rise of a vibrant interactive environment promoting learning, knowledge integration and technological accumulation, which may be called a “technological public sphere”.
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Anil, Kivanc Ali. "Multi-criteria analysis in Naval Ship Design /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FAnil.pdf.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, March 2005.Thesis Advisor(s): Fotis Papoulias, Roman B. Statnikov. Includes bibliographical references (p. 241). Also available online.
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Cunningham, Andrew Donald. "Monte Carlo simulation in the marine environment." Thesis, Liverpool John Moores University, 2011. http://researchonline.ljmu.ac.uk/6001/.
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Veldhuis, Ivo. "Application of hydrogen marine systems in high-speed sea container transport." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/51284/.
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Conventional marine fuels have always limited the endurance of high-speed ships leading to fast but inefficient cargo ships. This research considers the fuel weight barrier in high-speed ship design and the use of hydrogen as a marine fuel to overcome this barrier. Simultaneously, it is now accepted that environmental pollution from ships, particularly large containerships, contributes to climate change. Hydrogen marine utilization provides a solution for both. As common to other hydrogen research the fuel system spans production to utilization. This hydrogen marine system utilizes an established production method to obtain hydrogen from natural gas through steam methane reformation. To achieve an acceptable storage volume meeting the typical highspeed ship dimensions the hydrogen also requires liquefaction. The hydrogen is then converted onboard into shaft power via combustion in aero-derivative gas turbines. This research establishes the necessary system components spanning both onshore and ship components. The novelty of the research has resulted in new design tools. Research into large hydrogen transport applications is not new and a substantial body of research is available from passenger aviation studies performed during the 1980s and 1990s. Additionally, a more current body of research is available describing hydrogen utilization in large gas turbines for energy and oil/gas industries. This combined research provides the characteristics of the onboard hydrogen system of a high-speed foil-assisted containership. This ship is capable of transporting 600 industry standard 20’ containers on long-haul ocean routes, i.e. 5000 nautical miles, at a speed of 64 knots (118.5 km/hr). Such ship performance is not feasible with conventional marine fuels. The design is complex involving a combination of buoyancy and dynamic lift and two distinct operational modes at floating and dynamic draughts. Research involving this ship configuration is included here in conjuction with suitable design methodologies. Besides technical feasibility, economic feasibility of this containership has also been investigated based around the unit transport price required to recoup costs and achieve zero net present value. Such analysis identified that the containership has higher minimum freight rates than conventional containerships but substantially lower rates than aviation cargo. Due to its high-speed and improved endurance it can compete with aviation on transport time and price. Economic review also identified that shorter container door-to-door times are now demanded by the consumer production industry and this hydrogen marine container transport system meets this demand.
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Boyd, Stephen William. "Strength and durability of steel to composite joints for marine application." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/142615/.
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This thesis deals with the assessment of the strength and durability of steel to composite joints for composite superstructures on ships where reduced weight is a design driver. The purpose of the work is to understand the long-term performance characteristics of hybrid connections to allow for improvements to the design of hybrid structures. Two joints were investigated in the present research. The first was a full-scale connection suitable for application in superstructures of marine vehicles, specifically a helicopter hanger on a naval vessel. The second was a generic steel/composite connection for testing performance after hygrothermal ageing. The strength and durability of the full-scale connection were examined in compression, the loading scenario representative of in-service conditions. The results indicated that the static and fatigue performance were in excess of the realistic in-service loading conditions. Failure for both static and fatigue tests were comparable and therefore good confidence in the prediction of the joint’s failure was achieved. The generic hybrid connection was artificially aged through immersion in water. The results indicated that there was no significant reduction in the performance of the joint in either static tension or bending. The numerical modelling highlighted a number of issues. Due to the geometry of the joint high stress concentration factors were observed in some locations. It is in these areas that failure of the joint was predicted in the numerical modelling. Similar results were obtained experimentally and this gave confidence in the modelling of the joint. Numerical parametric and optimisation studies were conducted to assess the influence of the joint geometry on performance characteristics obtained from both the experimental and numerical studies. This highlighted that improvements to the performance of the joint could be obtained through geometric changes alone.
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Lillis, Julia A. "Analysis of the applicability of aircraft vulnerability assessment and reduction techniques to small surface craft." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FLillis.pdf.
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Price, David J. "Comparison of approaches for determining the failure of stiffened cylindrical shells /." Springfield, Va. : Available from National Technical Information Service, 2002. http://handle.dtic.mil/100.2/ADA405710.
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Thesis (M.S. in Naval Architecture and Marine Engineering and M.S. in Mechanical Engineering)--Massachusetts Institute of Technology, 2002.Includes bibliographical references (p. 57). Also available online.
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Pham, Xuan Phuc. "Green water and loading on high speed containerships." Thesis, Connect to e-thesis, 2008. http://theses.gla.ac.uk/249/.
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Thesis (Ph.D.) - University of Glasgow, 2008.Ph.D. thesis submitted to the Department of Naval Architecture and Marine Engineering, Faculty of Engineering, University of Glasgow, 2008. Includes bibliographical references. Print copy also available.
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Whalen, Todd E. "Optimal deadrise hull analysis and design space study of naval special warfare high speed planing boats." Thesis, Springfield, Va. : Available from National Technical Information Service, 2002. http://handle.dtic.mil/100.2/ADA405933.
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Thesis (M.S. in Naval Architecture and Marine Engineering and M.S. in Civil and Environmental Engineering)--Massachusetts Institute of Technology, 2002.Includes bibliographical references (leaves 64-65). Also available online.
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Maistralis, Eleftherios. "Formal safety assessment of marine applications." Thesis, Liverpool John Moores University, 2007. http://researchonline.ljmu.ac.uk/5843/.
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This research has first established that it is based on multiple methodologies developed to tackle the areas of engineering cargo handling systems, both at port and on-board vessels, as well as in the area of organisational self-assessment. It continued in reviewing the current status and future aspects of marine safety assessment together with an examination of a few major accidents. The major problems identified in marine safety assessment in this research are associated with inappropriate treatment of uncertainty in data and human error issues during the risk modelling estimation process and the calculation of failure probabilities. Following the identification of the research needs, this thesis has developed several analytical models for the safety assessment of cargo handling systems and organisational assessment structure. Such models can be effectively integrated into a risk-based framework using the marine formal safety assessment, safety case concepts. Bayesian network (BN) and evidential reasoning (ER) approaches applicable to cargo handling engineering systems have been proposed for systematically and effectively addressing uncertainty due to randomness and vagueness in data respectively. ER test cases for both a vessel selection process and a comparison of the safety maturity of different organisations in terms of self-assessment have been produced within a domain in which main and sub criteria have been developed for assessment reasons a long with the combination of the proposed model with existing organisational models. BN test case for a Liquefied Petroleum Gas (LPG) reliquefaction plant has been produced within a cause-effect domain in which Bayes' theorem is the focal mechanism of inference processing. A methodology aiming in finding the probability of failure when having variables ruled by uncertainty is established using certain variable transformation methods through the First and Second order reliability methodologies. Form/Sorm produces a most likely failure point, which is demonstrated through the application at a port cargo handling crane system. The outcomes have the potential to facilitate the decision-making process in a risk-based framework. Finally, the results of the research are summarised and areas where further research is required to improve the developed methodologies are outlined.
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Wang, Yikun. "Ultimate strength and mechano-electrochemical investigations of steel marine structures subject to corrosion." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/378219/.
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It is well known that ageing steel marine structures are susceptible to corrosion in its all manifestations. The most critical areas are cargo and ballast tanks of merchant ships. However, due to the regulations such as the Performance Standard for Protective Coatings, which requires a 15-year target life of coating in ballast tanks, plus the cathodic protection systems, the internal structures within cargo holds have become more problematic but poorly studied. In the underdeck area and bottom plating, the structures are not normally fully protected. Also, the complex structural arrangement may place difficulties in inspection and repair. In extreme cases, it has been reported that the corrosion rate in these areas could be 5 to 7 times higher than a normal value, and has led to catastrophic structural failures. Currently, the classification societies apply both visual and gauging methods for corrosion inspection during ship surveys. However, it is time consuming especially for large vessels and is highly experience dependent. Therefore, to improve the survey efficiency, facilitate economical maintenance decisions, and even extend the structural life, it is essential to investigate the ultimate strength of such aged and corroded steel structures. Based on the identification of existing corrosion issues in cargo tanks of oil tankers and bulk carriers and the state-of-art of corroded marine structural strength assessments, a nonlinear finite element method was adopted to investigate the influences of pitting and grooving corrosion on the structural integrity. Two full-field experimental techniques were used for a complete validation of the numerical models. Based on the repair conditions provided by classification societies, the numerical results showed that 25% locally corroded area of a plate (800 mm × 800 mm × 15 mm) with 3.75 mm remaining thickness may reduce the ultimate strength by up to 20% compared to a uniformly corroded plate. The weld-induced grooving corrosion of a width of 59 mm and a remaining thickness of 3.75 mm would cause up to 26% strength capacity reduction for a stiffened plate (4750 mm × 950 mm × 15 mm). Moreover, it was shown that the corrosion depth had a greater influence on structural performance compared to corrosion area for the same volume/material loss. By combining mechano-electrochemical protocols with the stress and strain results obtained from the modelling, it enables predictions of the ‘hot spot’ locations of mechanically-induced corrosion acceleration. Results showed that the anodic current density inside grooving corrosion damage (24 mm in width and 3.75 mm in depth) was 7 times greater vis-a-vis the unstressed condition for the stiffened plate at its ultimate strength state. The results, which are closely related to the industrial corrosion inspection and repair requirement, will not only benefit the shipping industry, but are also applicable to a whole range of marine structures (offshore platforms and steel bridges).
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Stratmann, Johannes Philipp. "Engineering management of early stage warship design." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/142859/.
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Warship Feasibility Studies are highly complex projects. The thesis attempts to highlight the relevant factors inherent within industry and academia and then derives a methodology for managing early stage warship design. The initial data were gathered at the VT shipyard by interviewing key personnel. The collected data are then analysed using the MS Visio flowchart package to create input/output diagrams for all existing areas of work. Identifying explicit and implicit links allows the existing areas of work to be linked and inherent areas to be identified. The resulting connection diagrams are then analysed and compared with existing literature. The analysis results in the creation of several loops depicting the data flow during the assessment phase. Two case studies are carried out to further refine the developed interface model. This model is further improved by carrying out in-depth investigations into previously neglected design factors. A series of algorithms are developed that can be used to determine balanced designs for corvettes and fast attack craft. These algorithms are used to identify factors and events that need extra attention during the design process. Different tools for managing the dataflow across the identified interfaces are researched and a set of control mechanisms is described in more detail. One mechanism, Margins, is further investigated using the developed algorithms in combination with knowledge obtained at VT to determine suitable margin ranges and applications. The results from the interface analysis and interface management studies are combined to derive a management methodology, consisting of a project schedule, a set of functional flowcharts and an accompanying guidance manual. This methodology is tested and validated on a design study. The results from the validation are used to determine any required changes to the methodology. The developed methodology is found to provide an effective tool for managers and designers during the early stages of warship design in a defence environment.
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Sampathkumar, Narasimhan. "Three dimensional geometrical and material nonlinear finite element analysis of adhesively bonded joints for marine structures." Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/142767/.
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The use of adhesive bonding as a structural joining method has been gaining recognition in marine industry in recent years, though it has been widely adopted in other fields such as aerospace, automobiles, trains and in civil constructions. The type of materials used and design practices followed in marine structures are different from what is applied in other disciplines. Therefore new research approaches are required and recent novel ideas are ex- plored in the context of application of bonded joint configurations in marine environment. The research is directed at developing analysis tools for predicting the displacement, stress and strain fields in adhesively bonded joints between dissimilar adherends. In the finite element formulation, the adherends may be isotropic or orthotropic layered materi- als, which are assumed to behave linear elastically. The adhesive material is assumed to behave as elasto-plastic continuum, where the nonlinear behaviour is modelled as either a rigid or a semi-rigid adhesive solid that can be represented by the Ramberg-Osgood ma- terial model. The yield behaviour of the polymeric adhesive is modelled using a modified von Mises criterion, which accounts for the fact that plastic yielding of polymer materials may occur under the action of hydrostatic as well as deviatoric stresses. The geometric nonlinearity is based on the assumption of large displacement, large rotation but small strain, and it is implemented in the code using the total Lagrangian approach. The scheme is applied on three case studies viz.: a study of adherend imbalances in a single lap joint, stress analysis of a butt-strap joint system and a hybrid joint are un- dertaken. The influence of geometric and material nonlinearity on joint deformations and adhesive stresses, are studied for a single lap joint with dissimilar adherends, aluminium and a Fibre Reinforced plastic composite material, with varying adhrend thickness ratios. The adhesive stress-strain data obtained from the model are compared with the exper- imental stress-strain curve and the numerical results are validated with the analytical solution. Three dimensional effects like ’anticlastic’ and bending-twisting’ are shown in the joint with a dissimilar adherends. Key results are obtained that explains the state of nonlinear adhesive stress state in the joint. Analysis of butt-strap joint focussed on nonlinear modelling of a semi-rigid adhesive ma- terial that is used to bond two dissimilar adherends, steel and aluminium. The analysis demonstrate that the influence of geometric and material nonlinearity on the joint de- formations as well as the adhesive stresses is significant. Nonlinear adhesive stresses are compared with the actual strength of the highly flexible adhesive, highlighting the need for the consideration of material nonlinearity in the bonded joints. Failure modes for the joint are inferred from the observations made on the adhesive stress state in the butt-strap joint. Last study, deals with three dimensional analysis of a GRP-Steel hybrid joint carried out to model the initiation and propagation of crack under a set of static loading cases. Earlier studies were restricted only to two dimensional analysis. This three dimensional analysis showed that the adhesive normal stress is not constant across the width of the joint. Critical locations of stress concentrations are identified and the failure mechanisms are compared with the experimental specimens. The observations made from this research study using a three dimensional finite element program, compliments the present knowledge in the field of adhesively bonded joints.
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Paton, Jonathan. "Computational fluid dynamics and fluid structure interaction of yacht sails." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/14036/.
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This thesis focuses on the numerical simulation of yacht sails using both computational fluid dynamics (CFD) and fluid structure interaction (FSI) modelling. The modelling of yacht sails using RANS based CFD and the SST turbulence model is justified with validation against wind tunnel studies (Collie, 2005; Wilkinson, 1983). The CFD method is found to perform well, with the ability to predict flow separation, velocity and pressure profiles satisfactorily. This work is extended to look into multiple sail interaction and the impact of the mast upon performance. A FSI solution is proposed next, coupling viscous RANS based CFD and a structural code capable of modelling anistropic laminate sails (RELAX, 2009). The aim of this FSI solution is to offer the ability to investigate sails' performance and flying shapes more accurately than with current methods. The FSI solution is validated with the comparison to flying shapes of offwind sails from a bespoke wind tunnel experiment carried out at the University of Nottingham. The method predicted offwind flying shapes to a greater level of accuracy than previous methods. Finally the CFD and FSI solution described here above is showcased and used to model a full scale Volvo Open 70 racing yacht, including multiple offwind laminate sails, mast, hull, deck and twisted wind profile. The model is used to demonstrate the potential of viscous CFD and FSI to predict performance and aid in the design of high performance sails and yachts. The method predicted flying shapes and performance through a range of realistic sail trims providing valuable data for crews, naval architects and sail designers.
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Yu, Lei. "Fatigue reliability of ship structures." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/2259/.
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Today we are sitting on a huge wealth of structural reliability theory but its application in ship design and construction is far behind. Researchers and practitioners face a daunting task of dove-tailing the theoretical achievements into the established processes in the industry. The research is aimed to create a computational framework to facilitate fatigue reliability of ship structures. Modeling, transformation and optimization, the three key elements underlying the success of computational mechanics are adopted as the basic methodology through the research. The whole work is presented in a way that is most suitable for software development. The foundation of the framework is constituted of reliability methods at component level. Looking at the second-moment reliability theory from a minimum distance point of view the author derives a generic set of formulations that incorporate all major first and second order reliability methods (FORM, SORM). Practical ways to treat correlation and non- Gaussian variables are discussed in detail. Monte Carlo simulation (MCS) also accounts for significant part of the research with emphasis on variance reduction techniques in a proposed Markov chain kernel method. Existing response surface methods (RSM) are reviewed and improved with much weight given to sampling techniques and determination of the quadratic form. Time-variant problem is touched upon and methods to convert it to nested reliability problems are discussed. In the upper layer of the framework common fatigue damage models are compared. Random process simulation and rain-flow counting are used to study effect of wide-banded non-Gaussian process. At the center of this layer is spectral fatigue analysis based on SN curve and first-principle stress and hydrodynamic analysis. Pseudo-excitation is introduced to get linear equivalent stress RAO in the non-linear ship-wave system. Finally response surface method is applied to this model to calculate probability of failure and design sensitivity in the case studies of a double hull oil tanker and a bulk carrier.
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Tao, Zhixiang. "Theoretical and experimental investigations of large amplitude ship motions and loads in regular head seas." Thesis, University of Glasgow, 1996. http://theses.gla.ac.uk/6900/.
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The aim of this research is to develop computational tools to predict the large amplitude motions and loads on ships travelling with forward speed in waves. An experimental research programme was completed to validate the non-linear prediction method. In this thesis, the results of theoretical and experimental investigations to predict the non-linear ship motions, slamming pressures and bending moments in regular head seas are presented. The ship hull is considered to be a Timoshenko beam, where the vibratory elastic response of the ship is calculated by the modal superposition method with the solution represented in terms of a series of normal modes. It is assumed that the mode shapes and natural frequencies can be determined by a separate structural analysis where this modal information is appropriate to the vessel in the equilibrium reference condition when floating in calm water. The global dynamic shear force and bending moment values are predicted using two different methods:The first method developed is based on the elastic vibratory response due to the total hydrodynamic force; The other is based on the rigid body response due to the linear force superimposed with the elastic response due to the impact forces. The results by the elastic vibratory response due to the total hydrodynamic force (method 1) have a good agreement with the experimental results and these are much better than the results by the rigid body response superimposed with the elastic response (method 2). The non-linear effects due to the change of the hydrodynamic coefficients and the non-linear restoring force should be considered in the ship motion and load predictions. The nonlinearity of ship motions as well as a significant nonlinearity between the hogging and sagging wave and global bending moments are shown in the results obtained from the non-linear theoretical predictions and the experimental data. The non-linear ship motions and sea loads, predicted by the practical computational tools, newly developed in this thesis, can be used to further ship structural strength analysis and guide ship hull design.
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Wu, June Young. "SWATH vertical motions with emphasis on fixed fins control." Thesis, University of Glasgow, 1985. http://theses.gla.ac.uk/6935/.
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The SWATH ship has been claimed as one of the advanced high performance vessels which can provide good seakeeping characteristics as well as maintaining high speed in rough seas. Despite the considerable amount of research and development carried out in the last fifteen years, there is still a lack of design data in the open literature concerning many of the specialised aspects of SWATH design. Two of these areas are the motion characteristics of hulls which are operating fairly close to the water surface and the design of active control systems to reduce static trim and motions in waves. This study is an investigation, both theoretically and experimentally using a model, into SWATH motion characteristics in the vertical plane. It aims to have an understanding of the seakeeping behaviour with and without the effect of fins in waves. The computer program for the motion prediction involves the computation of the hydrodynamic coefficients of the equations of motion on the practical range of frequencies, depth of submergences and column widths. The effects of these factors on the sectional hydrodynamic coefficients are discussed and are curve-fitted into approximate formulae in order to save computer time. The total (three dimensional) hydrodynamic coefficients are integrated stripwise, taking into account the forward speed and viscous effects. Analytic methods for the wave induced exciting forces were formulated and obtained by two approaches; the modified Morison's formula and the strip theory. The sectional Froude-Krylov force, caused by the undisturbed incident wave pressure and a diffraction component resulting from the distortion of the wave train by the presence of the hull integrated over the mean immersed surface of the hull section. Phase differences of the sectional forces are considered during the integration procedure. The forward speed and viscous effects are included together. In addition, a series of laboratory tests in calm water and waves as well as theoretical studies aimed at the design of vertical-plane control surface (fins), which would keep the SWATH ship on a near level trim at speed in calm water and reducing the inherently low level of motion in wave have been carried out. The forces generated by fins are composed of inertia effects and viscous induced lift and cross-flow drag. Since the fins are attached to the hull, the lift-curve slope were corrected by the fin-body effect. Only after fins are considered in the study, the combination of the forward fins are believed could be summed linearly. However, the downwash effect on the after fins by the forward fins are not able to be included. Since the exciting and restoring forces of a SWATH involved are smaller than those of the comparable monohull, adequate control forces can be generated for a SWATH at speed by reasonably sized fins. The good agreement of the comparisons of the analytical calculations and the experimental measurements confirms the accuracy of the study.
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Djatmiko, Eko Budi. "Hydro-structural studies on swath type vessels." Thesis, University of Glasgow, 1992. http://theses.gla.ac.uk/5508/.
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This thesis presents a study on SWATH type vessels which is directed towards the collection and use for structural design of experimental data related to motions and primary dynamic loads of such vessels. This data will be of use in the validation of a mathematical model for motion and wave load predictions recently developed at the Department. Further, experimental data on slamming will also be acquired to lay a foundation for the future development of a reliable analytical model. Design loads pertinent to SWATHs comprising the extreme primary loads, lifetime cyclic loads and local panel pressures are then built upon the former findings to be of use in structural designs, especially in the determination of initial scantlings and fatigue characterisation. Examples are given throughout on the evaluation of hypothetical SWATHs operating in the North Atlantic. The underlying theoretical formulation of SWATH ship motions is presented together with a description of a newly developed motion prediction theory. This is followed by a clarification of the procedures for conducting seakeeping tests on SWATH models. Validation of the analytical motion model by the measured data of single and tandem strut SWATH models is then presented. Subsequently, practical applications of implementing motion predictions to the assessment of SWATH operatiblity in real seaways are described. Theoretical background of SWATH primary wave loads is briefly outlined. The enhancement of the motion program MARCHS to tackle the primary load on SWATHs is described. The development of experimental data on SWATH loadings by way of seakeeping techniques is presented. Correlation of this experimental data and the theoretical assessment is made to demonstrate the validity of the mathematical model so developed. Lifetime cyclic and extreme loads required in the fatigue and ultimate strength designs, respectively, are developed by applying long- and short-term wave statistics.
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Tveitnes, Trym. "Application of added mass theory in planing." Thesis, University of Glasgow, 2001. http://theses.gla.ac.uk/2890/.
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Prediction of the hydrodynamic forces on planing craft by strip method requires the force acting on two-dimensional sections in vertical motion on the free surface to be known. The motion of a transverse section of a prismatic hull in steady planing corresponds to a constant velocity water entry of a wedge shaped section. The force acting on the wedge section before the chines get wetted is found from a consideration of the rate of change of the section added mass. The current added mass impact theory does not give a satisfying definition of the change in added mass after chines wetting, and hence predictions of non-constant velocity water entry can not be made accurately. As a consequence, the theory is not applicable for use in prediction of the lifting force on hulls in unsteady planing or on hulls in steady planing with non-straight keel line, i.e. phenomena corresponding to non-constant water entry. Also, in unsteady planing, sections experience exit motion due to the pitch and heave response of the craft. If applying the added mass theory in exit predictions, the resulting force acts in the direction of motion, something in contradiction with intuition and common sense. The work described in this thesis has resulted in a new added mass theory for water entry and exit of transverse sections of typical planing craft. A program of numerical simulations and experiments with wedge shaped sections has been carried out, providing force data for water entry and exit of such bodies to and from the water. Analysis of these data have led to separation of the added mass and damping forces and to the development of quasi-empirical expressions applicable for both constant and non-constant velocity force predictions. Thus the new theory provides a basis for strip method for prediction of the unsteady motion forces of planing craft. Further, the new added mass theory for water entry has been applied to predict the steady planing lift force on slender body hulls, and consistency with published planing data has been found. Also, an empirical aspect ratio correction has been derived, allowing application to large aspect ratio (non-slender) planing hulls.
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Moatsos, Ioannis. "Ultimate strength of ship structures including thermal and corrosion effects : a time variant reliability based approach." Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/5326/.
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On December 17th 2002 the World Meteorological Organization issued a statement according to which the global mean surface temperature has risen and consequently 2002 was the warmest year in the 1961-2002 period. Positive sea surface temperature anomalies across much of the land and sea surface of the globe in general contributed to the near record temperature ranking for the year along with climate anomalies in many regions across the globe. Climate change as a result of global warming is a worldwide occurring phenomenon which the experts have only recently started to understand and which affects and significantly will affect us in the near future. The effects of climate change have been somehow neglected by the ship and offshore related academic and research communities. In the case of thermal effects on ships structures, unless the problem solved is temperature dependent, this type of stress has often been neglected and not been taken into account in most types of analysis. The most likely reason behind this would seem to be that the stresses produced from temperature changes would be too small to be taken into account compared with still water loads or wave bending stresses. This is not the case though. Records exist of ships having broken in half while moored in still water and major hull factures occurred in still water while the temperature was changing as it can be seen from the relevant published literature. Very little work on thermal stress on ship structures has been published since the 1950s and 1960s and no work has been done that considers temperature effects on ultimate strength. Research undertaken aims to incorporate temperature effects on existing ultimate strength formulation by using a thermal stress approach, compare and use recently proposed corrosion models to model corrosion effects on ultimate strength and provide a foundation on which reliability analysis could then be performed for Tanker/FPSO structures operating in the North Sea. After comparing a number of possible approaches that would enable to loading components to be combined in a stochastic fashion, the loading part of the reliability analysis is handled using extreme wave statistics and the Ferry Borges-Castanheta load combination method. Annual reliability indices and probabilities of failure are calculated for hogging and sagging conditions using both time-variant and time-invariant approaches and a variety of reliability analysis approaches showing the effects of temperature along with partial Safety Factors for all variables taken into account.
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Fawcett, Stephen P. M. "A chart display and navigation information system for integrated bridge." Thesis, Liverpool John Moores University, 1992. http://researchonline.ljmu.ac.uk/4940/.
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Kader, Ab Saman Abd. "Cost modelling for inland waterway transport systems." Thesis, Liverpool John Moores University, 1997. http://researchonline.ljmu.ac.uk/5576/.
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Inland waterways have proven to be a significant mode of infrastructure for the carriage of freight. Examples of this can be seen in many developed regions such as Continental Europe, the United States of America and to a lesser extent, the United Kingdom. The benefit resulting from the existence of waterways are enormous in both transportational and non-transportational benefits. Hence there are considerable benefits which will result from a sustained development of waterways. This study identifies all relevant parameters associated with the waterways system. They include the waterway route, the barge provision to carry the cargo and terminal facilities as an interface point for cargo handling operations. Methods have been determined to enable various costs to be estimated. This estimating procedure can be very useful for a preliminary evaluation of development proposals pending a more detailed cost analysis. Estimated benefits can also be quantified at this preliminary stage. Data has been collected from a number of reliable sources. Models have successfully been generated and each model has been validated to an acceptable level of accuracy. The analysis has been applied to a proposed development of an inland waterway transportation system in the Klang Valley region of Malaysia. The results indicate viability for the scheme and, moreover, show the degree to which designers and planners can benefit from the use of the models.
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Saydan, Deniz. "Damage stability of ships as a safety criterion for optimisation tools." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/142587/.
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A literature overview of past optimisation studies revealed that whilst satisfaction of intact stability requirements has been built into existing alternative hull form optimisation packages, seeking improved hydrodynamic hull forms in terms of seakeeping, calm water resistance and added resistance, damage stability is not an automated feature. Within the context of the hydrodynamic hull form optimisation techniques their application to novel hull forms would only permit use of deterministic damage stability analysis and as this is not straight-forward damage is applied after the hull is optimised. The damage must be relevant to ship type and applied in appropriate locations with sensible extents of damage. To fulfil this need both the Marine Accident Investigation Branch (MAIB) damage data base and a damage data base generated by Lutzen (2002) are interrogated and findings are reported. The hydrodynamic analysis of the optimised hull and basis hull for the intact and damage cases is thereafter carried out using a three-dimensional singularity distribution method. The relative vertical motion responses of both intact and damaged hull forms are determined with greater structural cross-coupling than is usually applied in the solution of the equations of ship motions. This has necessitated the development of a novel approach to implement the calculation of the pure and product moment of inertias for the intact and damaged hull forms to facilitate meaningful comparison of intact and damaged ship motions. The processes are equally applicable to any kind of ship.
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Valgma, Mari. "Hygrothermal ageing and its effects on the flexural properties and failure modes of plant oil based composites for maritime applications." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366582/.
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This research looks at moisture uptake and its effects on the flexural properties of glass reinforced epoxy, linseed oil and castor oil composites. Water uptake damages the material through chemical, physical and mechanical ageing. At the same time there is a need to reduce the environmental effects of the maritime industry and using composites from renewable resources could be a viable solution. While the conventional composites like glass/epoxy are trusted as a structural material in harsh humid conditions, there is very little known about more sustainable composite materials. As resins have a greater environmental impact when manufactured, and no information on their long term performance is available, this research looks at the flexural performance of glass reinforced castor and linseed oil resins over 2 years of ageing in comparison with glass/epoxy. As a result of accelerated ageing it has been shown that the degradation of all three composites is significant, ranging between 18{87% over the 2 year testing period. The moisture equilibrium content in glass/epoxy was 2.11%, glass/castor oil 3.62% and glass/linseed oil 2.87%. While the moisture uptake of glass/epoxy follows an expected trend, the moisture uptake of plant oil based resin composites does not and differs from conventional models. After 2 years of ageing the properties of glass/castor oil are comparable with glass/epoxy. The degradation of properties in glass/linseed oil is the greatest. MicroCT and AE techniques were used to look at the failure modes in glass/epoxy and glass/linseed oil specimens showing changes in the failure mode of glass/linseed oil only after 3 days of ageing. The failure modes of glass/epoxy were found to be mainly fibre dominated and most of the damage occurred on the tensile side of the specimens while the failure in glass/linseed oil was largely dominated by compressive damage. For the first time the failure mechanisms of glass/linseed oil have been proposed.
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Roberton, D. M. V. "Life extension of composite structures with application to all weather lifeboats." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/386120/.
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With world shipping and other maritime based industries tending to operate assets requiring a large capital investment representing over half the total operating cost of the vessel, considering life extension at the end of a structure’s design life can postpone further capital investment and reduce the yearly operating costs of a particular asset for the owner. Despite this experience the concept of asset life extension for continued use once design life is exceeded is one which has been covered in very limited detail in the academic community. In more recent years the concept of asset life extension has become important to a growing number of maritime industries and as such has become an industry lead area for investigation, with the lead being taken by the Health and Safety Executive in the UK and other regulatory bodies abroad. The work presented here describes the investigations into life extension assessment of assets, with a special focus on the Severn class lifeboat fleet owned by the RNLI, who wish to assess the potential for life extension of this fleet to enable the continued use of a successful asset and offset a £120 million replacement program. The vessels themselves are a monolithic stiffened composite construction with a design life of 25 years. A methodology is devised which uses material static and fatigue data, environmental conditions and structural response data to determine the expected useful life of a composite structure. This methodology is then applied to the Severn class fleet by conducting experiments to determine the fatigue life of the materials through coupon tests, understanding the environmental conditions and the errors involved in predicting them and carrying out measurements of the structural response of a Severn class lifeboat whilst in service. Combining these variables using Monte Carlo simulations and the Miner’s rule allows an estimate of the useful life of the asset to be made.
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Palmer, Alistair Robin. "Analysis of the propulsion and manoeuvring characteristics of survey-style AUVs and the development of a multi-purpose AUV." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/72149/.
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Autonomous Underwater Vehicles (AUVs) are a developing technology with multiple applications including oceanographic research, military missions and commercial activities such as oil and gas field exploration. The reported research covers two main areas, namely, the assessment of the survey performance of AUVs and the development of the next generation of multi-purpose AUVs. The performance characteristics of long range survey-style AUVs are examined and improvements in performance are sought through the use of hybrid devices. Hybrid devices are defined as those that provide both propulsion and manoeuvring forces. Two devices were chosen for detailed investigation; a vectored thruster and a collective and cyclic pitch propeller. The manoeuvring performance of both devices was found to be insufficient to justify the additional engineering complexity associated with them. The aim of the next generation of AUVs is to be able to combine long range survey capabilities with low speed investigation of the environment encountered. An assessment of a likely mission profile and a review of the available design options demonstrate that maintaining the survey efficiency of the AUV is of principal importance. Therefore the investigation focuses on approaches to the addition of low speed control to an existing survey-style AUV design using propeller based thrusters. Externally mounted thrusters and through-body tunnel thrusters are reviewed and new experimental investigations are reported to provide insight into the performance characteristics on a survey-style AUV hull form. The main body of the experimental programme characterises forward and aft mounted tunnel thruster performance over a range of forward speeds and small yaw angles. The results are used to develop a new, simple modelling procedure representing the performance of tunnel thrusters on an AUV which facilitates the incorporation of the characteristics of tunnel thrusters into numerical simulations of AUV performance. Such a simulation is used to examine approaches to undertaking the transition phase between high speed survey and low speed manoeuvring operation. The results demonstrate the advantageous nature of undertaking a smooth interchange between control approaches considering both the vehicle performance and the energy demands.
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Rattanasiri, Pareecha. "Optimisation of a fleet of autonomous underwater vehicles to minimise energy dissipation." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366503/.
Full textAbstract:
The range of an AUV is dictated by its finite energy source and minimising the energy consumption is required to maximise its endurance. For an individual AUV, this may be achieved by obtaining the optimum hydrodynamic hull shape design. For a fleet of multiple AUVs, this may be targeted for both individuals and the entire fleet. The purpose of this work is, firstly, to develop a rational approach to find an optimal hull shape, secondly, to provide guidance for operators on suitable configuration for multiple AUVs' missions, finally, to investigate the influence of the propeller on the drag of twin self-propelled AUVs. An AUV hull form has been optimised to obtain low resistance hull. Hydrodynamic optimisation of hull form has been carried out by employing five parametric geometry models with a streamlined constraint. Three Genetic Algorithm optimisation procedures are applied by three simple drag predictions which are based on the potential flow method. The results highlight the effectiveness of considering the proposed hull shape optimisation procedure for the early stage of AUV hull design. The influence on the drag of the fleet of multiple towed prolate spheroids is investigated with various configurations and spacings. A series of three-dimensional simulations are performed using a commercial RANS-CFD code ANSYS CFX 12.1 with the SST turbulence closure model at the length Reynolds Number of 3:2 x 106. The results show that the spacing between two hulls determines the drags. Seven zones based on the drag characteristic of twin towed models are classified. Both the multi vehicle vee and echelon configurations show limited influence against that of the entire fleet's energy budget. Then the investigation extended to determine the combined drag of a pair of propelled prolate spheroids at various longitudinal offsets and transverse separations. The RANS-HO propeller models are selected to estimate the time averaged thrust and torque of the propeller. The results show that the self-propelled vehicles experience an additional drag which is dominated by the thrust distribution of the propeller rather than torque. The drag of the following AUV is increased due to the upstream propeller, defined as a propeller race deduction. The two sources of self-propelled drag increment are the viscous interaction and a direct result of proximity to the propeller race upstream. The result highlights the importance of both thrust deduction and propeller race deductions when calculating the propulsive power consumption. Based on this optimisation procedure and this numerical data, operators can design the optimal hull shape of an individual AUV including the determination of the optimal configurations in transverse separation and longitudinal offset based on energy considerations of fleets of multiple AUVs, it can be very effective at the early design stage.
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Man, S. "Aquatic flight inspired propulsion for autonomous underwater vehicles." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/385840/.
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Modern Autonomous Underwater Vehicle (AUV) technology has a number of limitations and one of these is vehicle manoeuvrability. Conventional flight style AUVs generally have turning circle diameters of five or more vehicle lengths, but most marine animals can turn in under one body length. This shows there is merit in looking at marine animals for inspiration to improve the manoeuvrability of AUVs. Aquatic flight propulsion is one marine animal propulsion strategy that was identified early in the research as having the potential to full fill this role. Aquatic flight propulsion has been studied experimentally in the past, but most of the past research focused in one or two axis aquatic flight (foil pitch and dorsoventral roll). However, marine animal literatures show animal aquatic flight is a three axis problem and there is an additional motion component in anteroposterior yaw. The effect of this yaw motion is not well understood and this will be the focus of this thesis’s research. The effect of aquatic flight yaw motion is investigated using a combination of computation modelling and experimental studies. It found two-axis aquatic flight is better for producing propulsive thrust for most scenarios, but three-axis aquatic flight is useful for producing additional off axis force. In particular, the three axis slanted foil actuation path can produce a sizeable vertical force with very little change to the horizontal thrust coefficient, which would be very useful for a positively buoyant AUV to control its depth. The experiment verified the model’s results and many of the experiment data points were within 30% of the model prediction. The experiment has a relatively large uncertainty due to turbulences in the recirculating water channel, so 30% is a reasonably good fit. Whilst there is room for improvement for both the model and the experiment, the current model is sufficient to produce provisional estimates for actuator and control system design as well as identification of various cases of interest for further in depth analysis.
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Halswell, Peter K. "The vibrations of a flexible planing craft : hydroelasticity, boat motion and noise." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/378120/.
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The Royal National Lifeboat Institution (RNLI) is the charity that aims to save lives at sea. The RNLI D-class is a five metre inflatable lifeboat that is used near the shore in waves and surf. Anecdotal evidence indicates that the D-class has improved performance due to its unique, flexible, fabric structure, and this flexibility is highly likely to affect the vibrations generated by the D-class. The boat motion is experienced by the on-board crew, and the air and water borne noise are heard by the on-board crew and the wildlife. This thesis aims to measure these two types of vibration, predict the perception of these vibrations and measure the effects of hydroelasticity on both the vibration and perception. Three aspects of hydroelasticity were identified within the D-class: hydroelastic slamming, hydroelastic planing surfaces and global hydroelasticity. This gives a new perspective with which to view the effects of hydroelasticity. A four stage full-scale holistic hydroelastic experiment was performed with each stage aiming to trigger one aspect at a time. The four stages were: static tests, flat water trials, drop tests and wave trials. The D-class was fitted with 52 sensors to measure the boat motion, engine thrust, sponson and keel pressures, deck hinge angles, deck panel deflections and the fabric hull deformation. The static trials measured the shape of the D-class under only buoyancy and weight forces. The flat water trials measured the effect of a hydroelastic planing surface on the forward speed and investigated a phenomenon termed the pulsing motion. The drop tests were performed at full-scale and quasi-2D, and they measured the effect of hydroelastic slamming on the peak acceleration and predicted the Whole Body Vibration (WBV). The open-water wave trials investigated the global hydroelasticity. The static tests showed that the shape of the D-class was more dependent on the keel pressure than the sponson pressure. The flat water trials proved that a flexible planing surface decreases the forward speed by 0.44 knots. The pulsing motion surprisingly exhibited the highest forward speed and it is hypothesised that the structure achieved an unstable equilibrium position of minimal potential energy. The full-scale and quasi-2D drop tests demonstrated that hydroelasticity can affect the peak accelerations and WBV, but the trend was inverted when the drop height was varied from 0.5 m to 1 m. It is believed that the keel is the dominant component during the flat water trials and drop tests, and this is coupled with the fabric hull. No statistical difference was found in the wave trials results but this was explained through the drop test results. The predicted WBV from the wave trials does emphasises the need for a new WBV reduction strategy and incorporating an element of hydroelasticity along with other reduction methods could make a significant impact on the WBV. The airborne noise of the D-class was measured using ISO 14509. The airborne noise was above the limits set out by the European directive 2003/44/EC. A method was developed to measure the water borne noise of small High Speed Craft (HSC) in shallow waters. The water borne noise propagation was modelled using an Image source Transmission Loss (ImTL) model. The perception of the air and water borne noise by a harbour seal was predicted and it showed that the D-class is unlikely to cause damage to the auditory system at one metre but will definitely be audible to the seal at 20 m. The horizontal and vertical transmission loss through a shallow water channel was investigated.
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Lee, June. "Hydro-impact, fluid-structure interaction and structural response of modern racing yacht." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/142787/.
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In recent years, faster, lighter and bigger are the key issues in a modern racing yacht for extreme performance. As a result, many yachts have experienced various structural failures caused by the hydrodynamic impact or ’hydro-impact’ phenomenon by slamming. The structural failure by hydro-impact originates from the facts that the external hydro-impact load and fluid structure interaction effect is somewhat misled and when applying the load into current structural design, the ’dynamic’ load is typically, manipulated in a ’static’ way with fluid structure interaction effect, generally, ignored. In this thesis, the hydro-impact load by slamming, its fluid structure interaction effect and dynamic response of the local structure of the yacht are studied. Firstly, to acquire insight into the hydro-impact phenomenon, a series of drop tests and seakeeping-slamming tests are carried out with various sensing instruments of pressure transducers, accelerometer and ’slam patch system’ - a specific application form of generally known pressure panel - are installed. The slam patch system is designed and implemented to investigate the hydro-impact loads and fluid structure interaction effect of slamming. Afterward, the measured hydro-impact loads are summarised via statistical manipulations with regard to pressure and duration time. Secondly, impact pressure by the rules and regulations of various organisations are provided to compare it with the experimental results and structural response calculations. The applicability of the rules and regulations on the high performance racing yacht is also pointed out. Finally, the manipulated loads are used as input data to simulate the transient response of local structure of the yacht structure. Throughout this study, the dynamic and fluid structure interaction effect by hydroimpact phenomenon on local composite structure can be easily visualised and calculated in a conservative way through conventional finite element analysis work.
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Maneepan, Komsan. "Genetic algorithm based optimisation of FRP composite plates in ship structures." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/52012/.
Full textAbstract:
Composite materials (herein means Fibre Reinforced Plastic, FRP) are increasingly usedin the construction of marine vehicles because of their outstanding strength, stiffness and light weight properties. However, the use of FRP comes with difficulties in the design process as a result of the large number of design variables involved: composite material design, topologies and laminate schemes. All variables are related to each other leading to a high dimensional and flexible design space. It is hard to use traditional design methods in order to gain solutions for an initial design stage in a short time. Hence, this thesis deals with the presentation of a structural synthesis (optimisation framework) for plate components of composite ship structures. The framework broadly consists of an optimisation technique and structural analytical methods. To make the framework compatible with the nature of composite ship structural design problems, the Genetic Algorithm (GA) is selected as the optimisation tool because of its robustness, its ability in dealing with both continuous and discrete variables and its excellent searching for a global optimum. The typical plate types in a ship structure are the stiffened and unstiffened plates. For a stiffened plate, the combination of the grillage analysis of energy method based on Navier solution and an equivalent elastic properties approach are introduced. Using this, it is possible to produce layer by layer optimisation results for the base plate, web and crown of the stiffened plate. Unfortunately, solutions of the adopted grillage analysis do not cover the mechanical behaviour of the plate between stiffeners so the Higher-Order Shear Deformation Theory (HSDT) must be employed. This method provides accurate solutions for thin to moderately thick plates with a compromised computational time. Then stiffness, strength and stability can be considered in the design problem. In addition, to achieve the program of the structural synthesis, various computational modules are implemented according to the evaluation of composite micromechanics properties, maximum stress failure criteria and structural weight function. Then the main modules are validated with available resources. The usefulness of the program has been proved by comparing it with the optimal solutions from finite element software. Finally, many application examples of secondary and tertiary composite ship structures are presented. The optimal results prove the success of the optimisation framework. This could be evidence for further improvement to obtain a valuable structural optimisation tool.
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Veiga, Augusto Elisio Lessa. "The analysis of partially separated flow on sail systems using a sectional method." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/51287/.
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Yacht sail systems are subjected to low speed and transitional flow. Because of the supporting structure (mast and boom) of the sail system and the curvature of sail membrane, sail systems also have a partially separated flow. In this work, it is introduced the sectional method as a sail system flow analysis tool. The sectional method uses the surface discretization and it is based in the simultaneous approach for viscous-inviscid interaction but, it works independently to the initial panel mesh and inviscid panel method calculation, permitting the adjustment of sectional points to have a better local convergence. The sectional method is applied to the detection of separated flow regions by means of integral boundary layer parameters investigation. The investigation is used in cases of weak separation and strong separation, when analysing mast and sail configurations. The weak separation detection is applied to a three-dimensional sail shape in a sail design problem: the study of parameters such as twist and section curvature in order to control separation on the sail.
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Thornton, Blair. "The development of Zero-G class underwater robots : unrestricted attitude control using control moment gyros." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/142569/.
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The ‘Zero-G’ is designated as a new class of underwater robot that is capable of unrestricted attitude control. A novel control scheme based on internal actuation using Control Moment Gyros (CMGs) is proposed to provide Zero-G Class Autonomous Underwater Vehicles (AUVs) with this unique freedom in control. The equations of motion for a CMG actuated underwater robot are derived and a nonlinear feedback control law formulated based on energy considerations of the system’s coupled dynamics. Singularities, redundancy and null motion are discussed in the context of CMGs and a mathematical escapability condition is developed based on the differential geometry of null motion. A comprehensive geometric study of the singularities of a CMG pyramid is performed and together with considerations of the inverse kinematics of attitude control form the basis of a global steering law that exactly achieves the desired torques, whilst guaranteeing real-time singularity avoidance within a constrained workspace. The development of the CMG actuated Zero-G Class underwater robot IKURA is described. This is the first Zero-G Class prototype and is the first application of CMGs to underwater robots. A series of experiments to demonstrate the practical application of CMGs and verify the associated theoretical developments is described. The open-loop dynamics of the system and the exactness and real-time applicability of the CMG steering law are verified. Experiments are carried out to assess the performance of the proposed control law by comparing the response of the robot to that using alternative control laws that neglect the hydrodynamic interactions of the body and the coupled motion of the CMGs and body respectively. The control law demonstrates a faster response with a smaller overshoot for less overall control activity than the alternative methods. The ability to actively stabilise the passively unstable translational dynamics of the robot are verified. Next, the unrestricted attitude control capability is confirmed with the robot demonstrating the necessary range of attitude control to adopt and maintain any attitude on the surface of a sphere. Finally, the ability to stabilise any attitude while translating in surge is confirmed with the robot performing vertically pitched diving and surfacing in surge. This is the first time an underwater robot has performed such a manoeuvre. This research demonstrates that CMGs are capable of actively stabilising the passively unstable dynamics of an underwater robot with essentially zero-righting moment and are capable of providing it with unrestricted attitude control. The three-dimensional manoeuvring capabilities allow Zero-G Class underwater robots to plan and optimise their missions in a fully threedimensional manner, in a way that has not been possible previously. This study concludes that the application of CMGs for attitude control opens up a path to develop sophisticated Zero-G Class underwater robots and their application to new fields of underwater research.
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Badoe, C. "Design practice for the stern hull of a future twin-skeg ship using a high fidelity numerical approach." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/376987/.
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The ability to predict the powering performance of twin skeg LNG ship is a complex endeavour requiring appraisal of operating conditions and hydrodynamic analysis to arrive at a suitable stern design solution. Inherently coupled with the stern design process is the design optimization, namely the selection of most suitable geometrical parameters of the propulsor, control surface and their arrangements with respect to the hull. An approach to the stern design may commence with the prediction of general ship stern flow, hence its resistance and self-propulsion capabilities. Almost a century of experience exists regarding how to predict the resistance and powering capabilities of the twin skeg LNG ship. Despite this, improvement in numerical methods is still in high demand. A RANS based numerical approach is presented in this thesis to predict the resistance and powering performance of future twin skeg ships. This is supported by a meshing approach which easily blends the hull-skeg boundary layer to the free surface. Predicting the non-uniform wake in the propeller plane due to the hull-skeg and control surface interaction was identified as one of the main challenges in the stern design and powering assessment. To predict this within acceptable cost a sectorial approach was developed as part of the numerical method which discretizes the propeller plane into a series of radial and circumferential subdivisions. The local axial and tangential inflow conditions at each location can then be considered. This was coupled to a blade element momentum theory propeller code. The two-way coupling was found to be a computationally efficient tool for studying the powering performance of ships. To demonstrate the pertinence of the RANS based numerical approaches developed in this work a series of case studies has been analysed. These include: skeg-rudder-propeller interaction studies, propulsive characteristic of the KCS ship, and the resistance and self-propulsion characteristics of a future twin skeg LNG ship. These highlight the roles of the numerical approaches in the stern design process for future twin skeg ships. The techniques developed in this work enable the designer to predict the powering performance of future twin skeg LNG ships at a cost effective manner in the initial design stage.
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Turnock, Stephen Richard. "Prediction of ship rudder-propeller interaction using parallel computations and wind tunnel measurements." Thesis, University of Southampton, 1993. https://eprints.soton.ac.uk/48365/.
Full textAbstract:
A theoretical method has been developed to predict the forces developed due to the interaction between a ship rudder and propeller. A parallel lifting suface panel program (PALISUPAN) ha sbeen written in Occam2 which is designed to run across variable sized square arrays of transputers. thsi program forms teh basis of the theoretical method. The rudder and propeller are modelled separately. Their interaction is accounted for through an iterative process whereby their respective inflow velocity fields are modified using a circumferential average of the disturbance velcoity due to the other body. Prior to writing PALISUPAN, software techniques for the implementation of computational fluid dynamics algorithms across arrays of transputers were developed. The approach used is based on a geometric parallelism. At the outermost level on each transputer the particular CFD algorithm runs in parallel with a harness process. The harness controls teh communication across teh transputer array. to prove thsi concept an explicit finite volume solver for the two-dimensional Euler equations has been implemented. PALISUPAN itself uses a perturbation potential formulation and an explicit zero pressure loading condition is enforced at the trailing edge. Use of the communications harness greatky reduces code development time and although an implicit solver PALISUPAN gives good parallel performance. Wind tunnel tests were undertaken to derive experimental data for validation of the prediction method. These used a 3.5m x 2.5m low speed widn tunnel and a range of flow an dgeometrical parameters were tested. Total rudder forces and moments, propeller thrust and torque and quasi-steady rudder surface pressures were measured. Empirical relationships for teh prediction of rudder lift, drag and stall for use in ship manoeuvring studeis were also derived. The validated theoretical prediction for rudder-propeller interaction using PALISUPAN allows the detailed design of sjip rudder-propeller systems to be enhanced. The parallel performance of the pALISUPAN demonstrates the practicality of using transputer arrays to solve CFD problems.
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Godderidge, Bernhard. "A phenomenological rapid sloshing model for use as an operator guidance system on liquefied natural gas carriers." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/142869/.
Full textAbstract:
A concept for a non-intrusive sloshing guidance system based on a phenomenological Rapid Sloshing Model is proposed to reduce the operational risk of sloshing damage to LNG carriers. A numerical sloshing model is implemented in a commercial Navier-Stokes Computational Fluid Dynamics (CFD) code which uses a volume-of- fluid approach for the simulation of multi- fuid problems. The effect of spatial and temporal discretisation and turbulence is investigated using systematic variation. Dimensional analysis of the multiphase flow regime and examination of the relative velocity at the fluid interface show that an inhomogeneous multiphase model is appropriate for the simulation of a violent sloshing flow. This is conrmed by the good agreement with the experimental data of Hinatsu. The effect of fluid compressibility is investigated for sloshing impacts and a criterion based on wave propagation is developed to assess the importance of compressibility. When modelling sloshing with large air bubble entrainment, the choice of fluid compressibility model is shown to have a significant influence on pressure magnitude and frequency of oscillation required for structural assessment and a thermal energy model is required. The Rapid Sloshing Model (RSM) is based on the observation that the centre of mass of a sloshing fluid tends to follow a particular trajectory. Using a phenomenological modelling approach, the forces affecting the sloshing response are approximated with mathematical functions for restoring force, damping and sloshing impacts. Calculation times for the resulting equations are typically 0.1% of real time on a desktop PC. A case study of sloshing induced by periodic rotation and translation of two-dimensional longitudinal and transverse sections of membrane LNG tanks is carried out using RSM. RSM is set up using one CFD simulation not considered in the case study and the RSM solutions are then compared to the independent CFD solutions. The fluid momentum from RSM is usually within 5%{15% of the CFD solution for excitation at and near the first resonant period at a filling level near the critical depth. An irregular surge motion profile from an ITTC two-parameter spectrum is applied to the tank and the mean error from the RSM solution remains below 15% when using momentum and transverse force. When applied to sloshing with a 10% filling level excited by an irregular seaway a mean error of 9.6% is obtained. Compared to existing phenomenological modelling approaches the RSM methodology reduces the error by an order of magnitude in sloshing scenarios of practical interest. A non-intrusive sloshing guidance system based on the Rapid Sloshing Model which is suitable for installation on existing and newbuild LNG carriers can be implemented by applying motion data measured onboard to the RSM to provide operator guidance on the sloshing severity in partially filled LNG tanks. The RSM is set up for a particular LNG carrier with existing sloshing data from the design and class approval stages.
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Bardet, Raphaël Régis. "A life cycle assessment method for alternative material selection strategies in boat structures." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/210435/.
Full textAbstract:
In general the use of composites results in shorter production time, lightweight and lower maintenance costs to the marine industry in the leisure, fast and fishing boats sectors. The social and economic benefits of using composite materials have made users complacent about the pollution and the health and safety issues associated with these materials. As the perception of environmental problems changes with time, alternatives with lower emissions allowing for cleaner production and easier disposal must be investigated. Glass Reinforced Thermoplastics (GRTP) have been in use for many years in the automotive industry and aerospace. These materials are fast to process, solvent free, have an unlimited pot life and demonstrate better mechanical properties such as improved toughness compared to aluminium and Glass Reinforced Thermoset (GRTS). However, building boats with GRTP requires massive investment in equipment that ship builders do not currently undertake, such as curing ovens, autoclaves and plastic welding equipment. It is, thus, necessary to define a method to measure the environmental performance of this material in the context of marine structure. The present research presents a comparative study of four materials, namely steel, aluminium, GRTS and GRTP, in the above context. The outcome of the research defines a material selection framework for marine structures focusing primarily on environmental performance. The study focused on life cycle energy and material flows to represent environmental impact over the entire life of a boat and the methodology used respects Life Cycle Assessment (LCA) standards. The influence of the conventional marine structure design approach on LCA results was highlighted by the result of a grillage and a boat design study. These two studies also showed that the contribution of in-service fuel consumption to the life cycle energy has the most significant environmental impact. This impact is two to three orders of magnitude larger than the manufacturing environmental impact of the candidate materials. A boat study taking into account the results of the two above mentioned studies overcame this limitation. This boat study, referred as a boat synthesis, uses a constant fuel consumption as a design constraint for each material. It demonstrated that in some part of the studied design space, GRTP could offer the best material alternative, whereas in some other part, aluminium is the best alternative. In addition, the study also showed that steel could also be the least environmentally damaging material under some conditions, which goes against the common practice to build all small boats in GRTS
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Spenkuch, Thomas. "A Bayesian belief network approach for modelling tactical decision-making in a multiple yacht race simulator." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366587/.
Full textAbstract:
The importance of human factors has to be taken into account when determining a yacht’s performance over a course. The crew’s capabilities of technical skills, athletic performance, and his/her ability of making rational decisions under time pressure and in light of uncertainty of the future wind regime are important aspects that will determine the overall performance of a yacht-crew system. This thesis highlights the performance of such a yacht-crew system with a focus on the decision-making process of sailors. Aspects of human behaviour in sport and the decision-making process are explained considering the level of expertise and possible approaches of how to model them are shown. An artificial intelligence AI -system is developed that is capable of simulating the decision-making process of different sailing behaviours/styles as well as different expertise levels of sailors within a dynamically changing yacht racing environment. The constraints of the multiple fleet racing simulator Robo-Race (Scarponi 2008) were determined using a series of tests with real sailors identified three important constrains: (1) the predictable behaviour of the AI-yachts, (2) the predictable and unrealistic weather model and (3) the simple model describing the effects of yacht interaction. These restrictions and constraints that limited the real and AI-sailors natural sailing behaviour have been successfully removed in the updated version of Robo-Race. The new developed decision-making engine based on Decision Field Theory that uses Bayesian Belief Networks as the perceptual processor showed a clear superiority over the old rule-based decision-making engine. Extensive simulations demonstrate the feasibility of modelling various decision-making processes and therefore different behaviours and expertise levels of sailors. A good comparison was found with that obtained between the Robo-Race results and the Olympic fleet racing events.
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Fenner, James Lyon. "'British Small Craft' : the cultural geographies of mid-twentieth century technology and display." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14494/.
Full textAbstract:
The British Small Craft display, installed in 1963 as part of the Science Museum’s new Sailing Ships Gallery, comprised of a sequence of twenty showcases containing models of British boats—including fishing boats such as luggers, coracles, and cobles—arranged primarily by geographical region. The brainchild of the Keeper William Thomas O’Dea, the nautical themed gallery was complete with an ocean liner deck and bridge mezzanine central display area. It contained marine engines and navigational equipment in addition to the numerous varieties of international historical ship and boat models. Many of the British Small Craft displays included accessory models and landscape settings, with human figures and painted backdrops. The majority of the models were acquired by the museum during the interwar period, with staff actively pursuing model makers and local experts on information, plans and the miniature recreation of numerous regional boat types. Under the curatorship supervision of Geoffrey Swinford Laird Clowes this culminated in the temporary ‘British Fishing Boats’ Exhibition in the summer of 1936. However the earliest models dated back even further with several originating from the Victorian South Kensington Museum collections, appearing in the International Fisheries Exhibition of 1883. With the closure and removal of the Shipping Gallery in late 2012, the aim of this project is to produce a reflective historical and cultural geographical account of these British Small Craft displays held within the Science Museum. In this process it reveals the hidden stories behind the collection and individual boat models. The research therefore considers the former British Small Craft display in terms of its geographical visual and textual presentation of national and local identity, the cultural transference of knowledge from local regional areas to a national/international stage, its evocation of coastal and river landscapes, and its techniques of landscape/seascape miniaturisation in mid twentieth century Britain.
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Brisbane, John. "Striving to deliver supply chain excellence : a study of how BAE Sytems is developing supply chain management solutions within the naval defence business." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/627/.
Full textAbstract:
The research reported in this thesis is set within the context of Supply Chain Management within BAE SYSTEMS Naval Business. It explores issues and solutions concerning the optimisation of performance within an operating and business environment experiencing both internal and external pressures to adapt and manage change. This thesis commences with a review of the pertinent literature, identifying six gaps for the writer to address. This attracted a comparative study with two other service orientated industries. The comparison identified similarities and solution methodologies that would inform how best to approach the supply chain factors impacting upon the Naval Defence Industry. Utilising both qualitative and quantitative techniques, the research then progressed to examine the peculiarities of the company's supply chain. Through triangulation, the thesis generated conclusions both from a research and management perspective that were impacting the business. The main focus of this thesis, and thus its contribution to knowledge through addressing the six gaps, is based on how culture, collaboration and change are managed within complex supply chain environments. Through this research, the writer has derived theoretical models and approaches on how one may best address and manage performance driven supply chain initiatives within both the naval defence business and similarly complex service orientated industries.
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Lu, Linghai. "Inverse modelling and inverse simulation for system engineering and control applications." Thesis, University of Glasgow, 2007. http://theses.gla.ac.uk/2/.
Full textAbstract:
Following extensive development over the past two decades, techniques of inverse simulation have led to a range of successful applications, mainly in the fields of helicopter flight mechanics, aircraft handling qualities and associated issues in terms of model validation. However, the available methods still have some well-known limitations. The traditional methods based on the Newton-Raphson algorithm suffer from numerical problems such as high-frequency oscillations and can have limitations in their applicability due to problems of input-output redundancy. The existing approaches may also show a phenomenon which has been termed “constraint oscillations” which leads to low-frequency oscillatory behaviour in the inverse solutions. Moreover, the need for derivative information may limit their applicability for situations involving manoeuvre discontinuities, model discontinuities or input constraints. Two new methods are developed to overcome these issues. The first one, based on sensitivity-analysis theory, allows the Jacobian matrix to be calculated by solving a sensitivity equation and also overcomes problems of input-output redundancy. In addition, it can improve the accuracy of results compared with conventional methods and can deal with the problem of high-frequency oscillations to some extent. The second one, based on a constrained Nelder-Mead search-based optimisation algorithm, is completely derivative-free algorithm for inverse simulation. This approach eliminates problems which make traditional inverse simulation techniques difficult to apply in control applications involving discontinuous issues such as actuator amplitude or rate limits. This thesis also offers new insight into the relationship between mathematically based techniques of model inversion and the inverse simulation approach. The similarities and shortcomings of both these methodologies are explored. The findings point to the possibility that inverse simulation can be used successfully within the control system design process for feedforward controllers for model-based output-tracking control system structures. This avoids the more complicated and relatively tedious techniques of model inversion which have been used in the past for feedforward controller design. The methods of inverse simulation presented in this thesis have been applied to a number of problems which are concerned mainly with helicopter and ship control problems and include cases involving systems having nonminimum-phase characteristics. The analysis of results for these practical applications shows that the approaches developed and presented in this thesis are of practical importance. It is believed that these developments form a useful step in moving inverse simulation methods from the status of an academic research topic to a practical and robust set of tools for engineering system design.
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Angelopoulos, Nikolaos. "Damage detection and damage evolution monitoring of composite materials for naval applications using acoustic emission testing." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7597/.
Full textAbstract:
Maritime transport has profound importance for the world economy. Vessels of all sizes constantly transport large numbers of passengers and goods across the sea, often under adverse operational conditions. Vessels need to exhibit high levels of reliability, availability, maintainability and safety (RAMS). However, at the same time their performance needs to be optimised ensuring the lowest possible fuel consumption with the maximum operational capacity and range without compromising RAMS. Sweating of naval assets and profitability should be maximised for the operator ensuring investment in future projects and supporting the growth of maritime transport and world economy as a whole. Vessels have been traditionally manufactured using naval steel grades such AH, DH and EH. Smaller leisure and specialised purpose vessels such as patrol boats, etc. have been built using fibre-reinforced composite (FRC) materials. This trend is gradually penetrating the market of larger commercial vessels including freight and cruise ships. However, these are still the early days and further investigation of the optimum FRC manufacturing techniques and mechanical properties together with an in-depth understanding of the damage mechanics are required before such materials can become more commonplace. This project has investigated different glass FRCs using different manufacturing techniques. Glass fibres are preferred due to their lower cost in comparison with carbon fibres. The use of carbon FRCs in maritime applications is limited to the fabrication of racing and high performance speedboat vessels. Samples manufactured under laboratory conditions have been compared with those manufactured by a shipyard. It has been seen that the in-house samples had generally superior performance. Steel-to-composite joints have also been assessed including different designs. The effect of different features in the design such as drilled holes and bolts on the mechanical performance of the manufactured samples has also been evaluated. The damage mechanisms involved during damage propagation and features causing damage initiation have been considered. Damage initiation and subsequent evolution have been monitored using acoustic emission (AE). Various signal processing approaches have been employed (manual and automatic) for optimum evaluation of the AE data obtained in a semiquantitative manner. It has been shown that AE could be applied effectively for structural health monitoring of naval structures in the field. Several factors and parameters that need to be considered during acquisition and analysis have been successfully determined. The key results of the study together with mechanical testing and characterisation of samples employed are presented in summarised form within the present thesis.
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Eastridge, Jonathan R. "Investigation and Implementation of a Lifting Line Theory to Predict Propeller Performance." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/honors_theses/72.
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Numerous hydrodynamic theories may be used to predict the performance of marine propellers. The goal of this thesis is to investigate and implement a lifting line theory as a program written in FORTRAN and to test its capabilities on some Wageningen B-Series propellers. Special attention is given to the validation of the routines involved in the implementation of the theory. Difficulties were experienced in obtaining results that accurately reflect the published experimental results, and some discussion is included regarding possibilities for the sources of these errors. Also discussed are the results of other lifting line codes and their respective differences from the current implementation.
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Moat, Bengamin I. "Quantifying the effects of airflow distortion on anemometer wind speed measurements from merchant ships." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/207/.
Full textAbstract:
Anemometers on Voluntary Observing Ships (VOS) are usually located above the bridge in a region where the effects of air flow distortion, created by the presence of the ship, may be large. Until now it was not known whether measurements from such anemometers would be biased high or low, and the possible magnitude of any such bias was not known. Investigations into the airflow above merchant ships have been carried out experimentally using a low-speed wind tunnel and numerically using a commercial Computational Fluid Dynamics (CFD) code VECTIS. The investigations examined the airflow over simple block models of VOS shapes. The results of the investigations were compared to wind speed measurements made from the RRS Charles Darwin. Experimental and CFD techniques have been used to devise scaling rules that predict the effects of the flow distortion. Both techniques have shown that the pattern of the flow distortion above the bridge scales with the ‘step height’, H, of the model. In the case of a tanker, H is the ‘bridge to deck’ height, i.e. the height of the accommodation block above the deck, for bow-on flows. Close to the top of the bridge the flow is severely decelerated and may even reverse in direction. Using the upwind edge of the bridge as the origin of the scaled co-ordinate system, there is a definite line above the decelerated region along which the speed of the flow is equal to the undistorted wind speed. Above this ‘line of equality’ the wind speed increases to a maximum and then decreases with increased height to a free stream wind speed. Simple equations have been devised to predict the positions of the ‘line of equality’, the maximum wind speed and the minimum wind speed within the decelerated region. Comparisons of the results with wind speed data obtained from field measurements made using a number of anemometers located on the RRS Charles Darwin agreed well and have predicted a maximum wind speed increase of approximately 15 ±5 %. Comparisons with the field data have confirmed that CFD models can be used to predict the effects of airflow distortion above merchant ships. The investigation has demonstrated the ability of the wind tunnel and CFD approaches employed to provide a better understanding of the airflow over merchant ships. Both methods have contributed to improve the understanding of how the wind speed at anemometer sites on merchant ships is affected by the ships hull and superstructure.
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Osman, Hafiiz. "Ultrasonic disinfection using large area compact radial mode resonators." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30592/.
Full textAbstract:
Ultrasonic water treatment is based on the ability of an ultrasonic device to induce cavitation in the liquid, generating physical and chemical effects that can be used for biological inactivation. Effective treatment requires the ultrasonic device to generate intense cavitation field in a large treatment volume. Most conventional ultrasonic radiators fulfil only the first of these two requirements, rendering such devices highly unsuitable for use in high-volume, high-flow liquid processes. The present research investigates the design and performance of a new type of radial resonator in terms of their electromechanical characteristics, nonlinear behaviour, and their ability to treat synthetic ballast water with lower power consumption and short treatment times. The radial resonators were designed using finite element (FE) modelling, and the best designs related to their predicted modal behaviour and vibration uniformity were selected for fabrication and experimental evaluation. Experimental modal analysis (EMA) of the radial resonators showed excellent correlation with the FE models, deviating by only 0.3% at the tuned mode. Impedance analysis showed that the mechanical quality factor of the radial resonators are 28–165% higher than the commercial high-gain probe, but their coupling coefficients are 40–45% lower. Harmonic response characterisation (HRC) revealed shifts in the resonance frequencies at elevated excitation voltages. Duffing-like behaviour were observed in all resonators. RP-1 exhibited the Duffing-like behaviour to a far greater extent compared to the RPS-16 and RPST-16 multiple orifice resonators, indicating the influence of geometric parameters on the overall stiffness of the structure. Finally, experiments with Artemia nauplii and Daphnia sp. showed excellent biological inactivation capability of the radial resonators. Comparison with previous studies showed that 90% reduction in Artemia nauplii can be achieved with up to 33% less energy and using just one radial resonator compared to the dozens of conventional resonators used in precedent investigations. The present research have successfully demonstrated the use of FE modeling, EMA, and HRC to develop, validate, and characterise a new type of radial resonator. Experimental analysis showed that the radial resonators exhibited promising electrical, mechanical, and acoustical characteristics that has the potential to be cost-efficient, scalable, and a viable alternative water treatment method.
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Daniel, Liam Yannick. "Maritime forward scatter radar." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7831/.
Full textAbstract:
This thesis is dedicated to the study of forward scatter radar (FSR) in the marine environment. FSR is a class of bistatic radar where target detection occurs at very large bistatic angle, close to the radar baseline. It is a rarely studied radar topology and the maritime application is a completely novel area of research. The aim is to develop an easily deployed buoy mounted FSR network, which will provide perimeter protection for maritime assets—this thesis presents the initial stages of investigation. It introduces FSR and compares it to the more common monostatic/bistatic radar topologies, highlighting both benefits and limitations. Phenomenological principles are developed to allow formation of forward scatter signal models and provide deeper understanding of the parameters effecting the operation of an FSR system. Novel FSR hardware has been designed and manufactured and an extensive measurement campaign undertaken. The outcome of this was the creation of the first comprehensive maritime FSR target and clutter signal database—results from which have been shown with preliminary analysis. Alongside experimental work, a sea surface model has been produced in order to estimate the effects of wave blocking in high sea states and assess FSR performance in these conditions.
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Robb, Johnston Fraser. "Scotts of Greenock : shipbuilders and engineers, 1820-1920; a family enterprise." Thesis, University of Glasgow, 1993. http://theses.gla.ac.uk/1376/.
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It would be an exaggeration to claim that the history of a great industry like shipbuilding in Britain, can be fully understood by concentrating on the history of only one of the many companies that contributed to the developers. However, Scotts of Greenock represent a case study that in many ways encapsulates the critical ingredients which came together to project British shipbuilding from purely local significance to world leadership between the late eighteenth century and the beginning of the twentieth century. The roots of modern British shipbuilding lie in the craft industry based on wood and sail, one dominated by small scale family and partnership enterprises typical of the eighteenth and early nineteenth century. The Scotts grew out of this milieu, their family firm dating from 1711, and their survival from that date to the 1980s, marking them out as the longest surviving and oldest firm in British shipbuilding, probably the longest established shipbuilding enterprise in the world. Survival in the small scale world of local markets for wood and sail demanded ingenuity and flexibility, together with a willingness to tackle almost any type of related trade. The Scotts excelled in this unpredictable and opportunistic environment. In Chapter 1 which examines the characteristics of the family, their enterprise in the first century of activity between 1711 and 1820, the foundation of their success is set out.
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Lee, John Andrew. "Technical management of VLCC/VLBC hull structures based on safety case principles." Thesis, Liverpool John Moores University, 2008. http://researchonline.ljmu.ac.uk/5919/.
Full textAbstract:
Recent high profile accidents involving environmental damage caused by structural failures in ageing oil tankers and bulk carriers has highlighted the importance of structural integrity issues involving these types of ships. Between 1980 and 1996, there were 186 total losses of bulk and combination carriers and 1,278 lives lost. These events have led to concerns from the public, media and within the international maritime community, about deteriorating ship structural safety standards and the environmental impact. Evidence suggests that structural failure may account for more ship losses than hitherto believed. Industry critics have complained that the quality of designs for new tonnage and effectiveness of the present control mechanisms governing structural condition for vessels in service, are inadequate. Due to the relatively low safety margins inherent in modern commercial ship structural designs, a buyer beware policy prevails in ship procurement. A weakness in current ship design practice appears to be the difficulty of incorporating an owner's individual preferences. Recognising that to be effective, improvements in ship structural design must be implemented at the design stage, this study addresses the challenge of further improving the structural safety and performance of large bulk ships through exercising specific options related to the structural design of the ship within the remit of the buyer. A broad comprehensive literature survey was conducted to cast a wide net around the problem. The complex web of regulatory controls affecting the design and operation of bulk ship hull structures was analysed and problems involving design, construction and maintenance of these vessels were uncovered to build evidence to justify proposing an improved method. An analysis of recent high profile tanker and bulk carrier accidents involving structural failure was performed, to determine root causes. These findings formed the basis for a proposed novel risk-based "design for safety" framework The core of the method is the new evidential reasoning (ER) algorithm developed on the basis of a MCDA evaluation framework and the evidence combination rule of the Dempster-Shafer (D-S) Theory. A number of structural design options focused on the cargo tank mid body area of a typical double hull VLCC were evaluated. A set of quantitative and qualitative criteria were identified and articulated, leading to a structural evaluation framework for eliciting preferences for competing options. The MCDAlER model provides a risk-based, rational, transparent methodology for rapid techno-economic evaluation of alternative structural designs, putting buyers in a stronger position to balance risks and determine the expected structural safety outcomes of different designs. The ER modelling is performed using the Intelligent Decision System (IDS) software program developed by Yang and Xu. The method was tested with an example and validated through a sensitivity study. Finally, the evidence necessary for constructing and demonstrating the MCDAlER structural evaluation framework was used to build the arguments for a safety case approach to hull structures using the Australian Offshore safety case model. The safety case for hull structures is built upon a foundation of existing prescriptive statutory and classification society structural regulatory requirements. The advantages of the safety case applied to oil tankers were explained, including suggestions for a new regulatory approach. The application of new technology and tools was discussed.