Noon report data uncertainty

Noon report data is a low resolution dataset (sampling frequency of approximately 24 hours) from which it is possible to extract the principal variables required to define the ship’s performance in terms of fuel consumption. There are increasing economic and environmental incentives for ship owners and operators to develop tools to optimise operational decisions with the aim of reducing fuel consumption and/or maximising profit. Further, a ships current performance needs to be measured in order for fuel savings from technological interventions to be assessed. These tools and measurements may be based on models developed from historical trends that are extracted from noon reports; however there is inherent uncertainty in this dataset. As a prerequisite the uncertainty must be quantified to understand fully the potential and limitations of predictive models from which operational tools may be designed and of statistical models from which technological interventions are assessed. This paper initially presents a method for quantifying the uncertainty in reported fuel consumption using between two months and one year’s worth of data from 89 ships. The subsequently calculated confidence is then compared to the uncertainty in the data acquired from an on board continuous monitoring system

A Network-Based Design Synthesis of Distributed Ship Services Systems for a Non Nuclear Powered Submarine in Early Stage Design

Even though the early-stage design of a complex vessel is where the important decisions are made, the synthesis of the distributed ship service systems (DS3) often relies on “past practice” and simple vessel displacement based weight algorithms. Such an approach inhibits the ability of the concept designer to consider the impact of different DS3 options. It also reduces the ability to undertake Requirements Elucidation, especially regarding the DS3. Given the vital role the many DS3 provide to a submarine, this research considers whether there is a better way to synthesise DS3 without resorting to the detailed design of the distributed systems, which is usually inappropriate at the exploratory stages of design. The research proposes a new approach, termed the Network Block Approach (NBA), combining the advantages of the 3D physical based synthesis UCL Design Building Block (DBB) approach with the Virgina Tech Architectural Flow Optimisation (AFO) method, when applied to submarine DS3 design. Utilising a set of novel frameworks and the Paramarine CASD tool, the proposed approach also enabled the development of the submarine concept design at different levels of granularities, ranging from modelling individual spaces to various DS3 components and routings. The proposed approach also allowed the designer to balance the energy demands of various distributed systems, performing a steady-state flow simulation, and visualising the complexity of the submarine DS3 in a 3D multiplex network configuration. Such 3D based physical and network syntheses provide potential benefits in early-stage submarine DS3 design. The overall aim of proposing and demonstrating a novel integrated DS3 synthesis approach applicable to concept naval submarine design was achieved, although several issues and limitations emerged during both the development and the implementation of the approach. Through identification of the research limitations, areas for future work aimed at improving the proposal have been outlined

Synthesis of aesthetics for ship design

In the search for consensus on a definition of beauty, fitting the task of appreciating a ship’s design, this research revealed that other components of visual appraisal and 3d pattern analysis are required for a systemic approach. The model process presented is built around local adaptation and Gestalt psychology and uses retrospective case studies to categorise and calculate proportions, and recognisable patterns. The number of results from each type of vessel were found to be different, due to each ship or boats various geometries and anatomy, which illuminated the importance of standardising a procedure of categorisation in the appreciative approach.The categorisation of functions around the philosophy of functional beauty and the maths of summation series, it is suggested here, will allow a library of algebraic patterns and parameters to penetrate further into the impending or emulated integrated systems of ship design. The process to derive physical parameters via the culturally focussed narrative of functional beauty, is deemed as a manageable and novel addition to the naval architect's role. However, for the results to have a decisive impact on commercial design or education, variance and validation through further case studies is required

An Adaptive Parameterisation Method for Shape Optimisation Using Adjoint Sensitivities.

PhD Theses.Adjoint methods are the most e cient approach to compute the design sensitivities as the entire gradient vector of a single objective function is obtained in a single adjoint system solve. This in turn opens up a wide range of possibilities to parameterise the shape. Most shape parameterisation methods require manual set-up which typically results in a restricted design space. In this work, two parameterisation methods that can be derived automatically from existing information are extended to include adaptive design space in shape optimisation. The node-based method derives parameterisation directly from the computational mesh employed for simulation and normal displacements of the surface grid nodes are taken as design variables. This method o ers the richest design space for shape optimisation. However, this method requires an additional surface regularization method to annihilate high-frequency shape modes. Hence the best achievable design depends on the amount of smoothing applied on the design surface. An improved adaptive explicit surface regularization method is proposed in this thesis to capture superior shape modes in the design process. The NSPCC approach takes CAD descriptions as input and perturbs the control points of the NURBS boundary representation to modify the shape. The adaptive NSPCC method is proposed where the optimisation begins with a coarser design space and adapts to ner parameterisation during the design process. Driven by adjoint sensitivity information the control points on the design surfaces are adaptively enriched using knot insertion algorithm without modifying the shape. Both parameterisation methods are coupled in the adjoint-based shape optimisation process to reduce the total pressure loss of a turbine blade internal cooling channel. Based on analyses regarding the quality of the optima and the rate of convergence of the design process the adaptive NSPCC method outperforms both adaptive node-based and the static NSPCC approach

Challenges and potential of technology integration in modern ship management practices

This thesis explores the challenges and potential of technology integration in current ship management practices. While technology advancements were designed to be contributing to minimising task complexity, issues such as fatigue, increased administrative burden and technology assisted accidents still plague the industry. In spite of the clearly recognisable benefits of using modern technology in the management of ships, in practice its application appears lacking by a considerable margin. The main driver of the study was to appreciate the cause of this disparity. The study first reviewed a wide body of literature on issues involving the use of technology which included academic literature with empirical evidences and theoretical explanations of implementation of technology at work. With the help of the extant knowledge this research embarked on providing an explanation to the gap that existed in the application of technology in the shipping industry. By taking a case study approach the thesis looked into the induction and integration of technology in the management and operation of ships that primarily interfaced closely between the ship and its management unit on shore. Three companies with mutually diverse management setup were studied. The fourth case comprised of purposefully selected senior members of ships’ staff. The analysis of the data revealed that the manifestation of the gap in technology implementation is caused by deeper influences at work in the shipping industry. The un-optimised technology integration results in the seafarer, who is the keystone to the technology application, becoming a victim of the circumstances. The technology that was intended to ease operations and burdens ends up in controlling him, even leaving him under-resourced and causing fatigue.This was not an unintended outcome but the result of weak regulatory practices, short-term capital outlook and weakened labour practices in the shipping industry all caused by wider social and economic developments affecting not just this industry but businesses globally. The impact of such influences was however more acute in this industry resulting in such extreme consequence. By bringing to light the limited application of some fundamental principles of human-systems integration, this study has attempted to expand the boundaries of research on the subject and contributed to the holistic understanding of the various underlying factors that influence technology integration in ship management processes

Study into the use of the GNSS for maritime structure analysis

Certain civilian uses of the Global Positioning System (GPS) now demand levels of precision exceeding the original military specifications for the system. For example, at present, GPS is used in surveying, navigation and monitoring applications. Although GPS has been used previously to monitor the structural integrity of civilian structures such as bridges and towers, the experimental conditions have one significant difference: These structures are all immobile allowing for fixed references to be used.This research’s ultimate aim was to conduct a feasibility study into the use of GPS, and of the soon to be deployed Galileo constellation, in structural monitoring of maritime vessels. Under these conditions, a fixed base station as was used in previous structural monitoring is not a valid approach. New techniques, or variations on the current ones, were examined to deal with this lack of a fixed reference.This thesis considers the simulator that was developed in the early phases of the project and the results that were generated. An expanded version of the simulator is then explained, alongside the processes used to model structural deformation experienced by a ship at sea. Frequency analysis of the simulator results is also performed and the results detailed. It is found that frequency-domain analysis allows for the identification of different movements seen on the structure. In addition, an analysis of the impact the deployment of the Galileo constellation is conducted using simulation. This simulation found a drop of about 20% in Dilution of Precision (DOP) over several areas.This thesis then examines some of the field work, that aimed to measure rigidbody motion, that was conducted onboard Red Jet 4, a catamaran-type vessel. The experimental setup is described, and the results are briefly considered.A method for determining the optimal configuration of the receiver network is also proposed alongside an algorithm to detect plastic deformation of a vessel structure. Finally, this report considers the original project objectives and how these were or were not met. Should sufficient accuracy be achieved by a GPS receiver network, it is possible to use the system to monitor ship structures

Investigations of the magnetic fields from ships due to corrosion and its countermeasures

Corrosion is one of the main concerns for the shipping industry. The enormous cost associated with the corrosion of ships means that operators are more than ever seeking methods to provide optimal protection. Another problem which results from the corrosion of ships is that the electric currents produced give rise to a corrosion related magnetic field which adds to the ships overall electromagnetic field which can trigger underwater mines. Hence for the Admiralty to protect their fleet, they need to understand, predict and reduce these electromagnetic signatures. This will also be a concern for operators of merchant ships if, as recently suggested, terrorists begin to target them. There are a number of factors contributing to the electromagnetic signature of a ship. The work presented in this study is concerned with the magnetic field arising due to corrosion and the countermeasures employed against it (namely Impressed Current Cathodic Protection (ICCP) systems]. This field is called the Corrosion Related Magnetic (CRM) field. Since this field is directly related to the rate of corrosion of a ship, it may also be used as an indicator as to the efficiency of the corrosion protection measures, This work presents a range of techniques which may be used to model the CRM field. Simple dipole models are used to investigate the general behaviour of a corroding ship in sea water. These investigations result in an expression for an approximation of the CRM field from a dipole-wire configuration which can be used to estimate the CRM field from a corroding ship with an active ICCP system. A second, more detailed, method was then developed using the Boundary Element Method (BEM) to model a ship corroding in a tank of sea water. The BEM uses a large set of simultaneous equations, the coefficients of which are calculated by numerical integration using a new method based around the moments of triangular surface elements which discretise the boundary of the domain. By using a Point Successive Over-relaxation Method (PSOM) to solve the BEM equations, the electric potential and its flux are calculated for each discrete element on the boundary. These potentials are then used to evaluate the CRM field within the domain. Rather than use the Biot-Savart Law for this purpose, a new method is presented which removes the requirement for an internal volume mesh of the domain, allowing the CRM field to be calculated directly from the electric potentials of the surface elements. To test this method, results are presented for a tank of sea water with a hull located on the top surface and an appropriately placed propeller. Calculations were performed for an unprotected propeller and the hull with various degrees of protection from corrosion offered by paint coatings and an ICCP system. Results from the "exact" method are in good agreement with those from the simple dipole model and although there were no published results of the kind produced by this research available for comparison, published results from similar studies of related topics appear to further support the results presented. These results indicate that the method developed is capable of modelling all the key characteristics required for a detailed analysis of an actual corroding ship, with protective paint coatings and ICCP system, in a physical environment

CONTROL TECHNIQUES APPLIED TO INTEGRATED SHIP MOTION CONTROL

Fins stabilisers are devices which are fitted to the hull of a ship and utilised to ameliorate its rolling motions. They apply a regulated moment about the ship's axis of roll in order to oppose the sea induced disturbances. Recognising their unsurpassed performance, the Royal Navy, since the 1950's, equips all its vessels with fin stabilisers. It can be shown that the rudders, in vessels of appropriate size, also have the potential to be harnessed as roll stabilisers Rudder Roll Stabilisation (RRS) without degrading the ship's course-keeping. Thus creating a more stable platform for the human operators and equipment. The reported success of RRS imparted an impetus to the Royal Navy to initiate this study. The objectives are to ascertain whether RRS is possible without rudder modifications and to establish whether enhanced levels of stabilisation would accrue if the fins and RRS were operated in congress. The advantages in this novel approach being: avoidance of redesign and refit of rudders, three modes of operation (fins alone, RRS alone and combined RRS and fins), reduced fin activity and by implication self-generated noise, and amenability to be retrofitted by simple alteration of any existing ship's autopilot software. The study initially examined the mathematical models of the ship dynamics, defining deficiencies and evaluating sources of uncertainty. It was postulated that the dual purpose of the rudder can be separated into non-interacting frequency channels for controller design purposes. An integrated design methodology is adopted to the roll stabilisation problem. Investigating the capabilities of the rudder servomechanism, a new scheme, the Anti-Saturation Algorithm (ASA) was proposed which can eliminate slew rate saturation. Application of the ASA is generic to any servomechanism. The effects of lateral accelerations of the ship on human operators was examined. This resulted in an unique contribution to the Lateral Force Estimator problem in terms of generating time domain models and defining the limitations of the applicability of a control design strategy. Linear Quadratic Guassian and two types of classical controllers were constructed for the RRS and fins. A novel application of linear robust control theory to the ship roll stabilisation problem resulted in H . controllers whose performance was superior to the other design methods. This required the development of weight functions and the identification and quantification of possible sources of uncertainty. The structured singular value utilised this information to give comparable measures of robustness. The sea trials conducted represent the first experience of the integrated ship roll stabilisation approach. Experimental results are detailed. These afforded an invaluable opportunity to validate the software employed to predict ship motion. The data generated from the sea trials concurs with the simulations data in predicting that enhanced levels of roll stabilisation are possible without any modification to the rudder system. They also confirm that when the RRS is acting in congress with the fin stabilisers the activity of both actuators diminishes