Centre for Marine and Renewable Energy (MaREI) - Masters by Research Theses

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A case-study in the introduction of a digital-twin in a large-scale manufacturing facility
(University College Cork, 2020-11-02) O'Sullivan, Jamie; O'Sullivan, Dominic; Bruton, Ken; Science Foundation Ireland
The exponential increase in data produced in recent times has had a profound impact in all areas of society. In the field of industrial engineering, the knowledge produced by this newly obtained data is driving business forward. Automating the process of capturing data from industrial machines, analyzing it and using the knowledge gained to make better decisions for the machines is the crux of the digital twin. Digital twins uncover a wealth of knowledge about the physical asset they duplicate. Sensor technology, Internet of Things platforms, information and communication technology and smart analytics allow the digital twin to transform a physical asset into a connected smart item that is now part of a cyber physical system and that is far more valuable than when it existed in isolation. The digital twin can be adopted by the maintenance engineering industry to aid in the prediction of issues before they occur thus creating value for the business. This thesis discusses the introduction of a maintenance digital twin to a large-scale manufacturing facility. Issues that hamper such work are discovered and categorized to highlight the difficulty of the practical installation of this concept. The work here highlights the difficulties when working on digital systems in manufacturing facilities and how this isn’t discussed in journal articles and the disconnect between academia and industry on this topic. To aid in the installation, a digital twin framework is created that simplifies the digital twin development process into steps that can be completed independently. Work on implementing this framework is commenced and early successes highlight the benefit of sensoring critical assets. The payback of the initial practical work is immediate, and it presents a promising outlook for the iterative development of a maintenance digital twin using the framework. The thesis’ work highlights the benefit in reducing project scale and complexity and hence risk for digital systems in manufacturing facilities by following the framework developed. The later part of the thesis discusses machine learning and how this AI topic can be integrated into the digital twin to allow the digital asset to fulfill its potential.
An experimental investigation into the most prominent sources of uncertainty in wave tank testing of floating offshore wind turbines
(University College Cork, 2022-08-30) Lyden, Eoin; Murphy, Jimmy; Judge, Frances
There is an urgent need to replace carbon-based energy sources with renewable energy sources, and floating offshore wind is seen as a critical component in the drive towards energy diversification. Floating offshore wind facilitates accessing a far vaster wind resource that exists in deeper waters, further offshore. Floating offshore wind platforms must undergo wave tank testing in the early stages of development to assess model responses to different wave and wind conditions. Wave tank testing, while highly beneficial, is liable to errors arising throughout the testing campaign. Errors can arise during wave tank setup, testing, and analysis of results. Some of the primary sources of error include errors in the model location within the tank, errors in model parameters like mass, inertia and CoG, and errors due to incorrect replication of mooring forces and aerodynamic forces from the turbine. Scaling wind turbine blade properties can be challenging; this is because aerodynamic forces are scaled using Reynolds scaling, but all hydrodynamic forces are scaled using Froude scaling. For this reason, wind emulation systems are used to replicate the aerodynamic forces from the turbine only. Testing was completed using two very different floating offshore wind concepts. A sensitivity analysis was completed by conducting variations to the wind emulation system used, the model inertia and centre of gravity, and the mooring stiffness of the model. The magnitudes of the variations to the inertia, centre of gravity and mooring stiffness were based on the uncertainty in the values of each of the parameters. Three wind emulation systems of varying complexity were used for this comparison, a simple weighted pulley system, a constant thruster and the software in the loop system developed by CENER. The comparison was conducted to assess the influence of wind emulation systems on the uncertainty of platform response It was found that the effects of each variation conducted were magnified at resonance, and the magnitude of platform response was affected to a greater extent than the period of resonance response. Of all the variations to the model properties conducted, the inertia about the y-axis and location of the centre of gravity along the x-axis affected pitch response to the greatest extent. A 7% change in the inertia about the y-axis coupled with an 8.57% resulted in a 10% change in the period of resonance response for pitch, Tr, and 52% decrease in the magnitude of resonance respsonse for pitch, Tr, mag. Changes in the wind emulation system affected the pitch response most significantly, while the period of resonance response Tr, was mostly unaffected , the magnitude of resonance response Tr, mag, was reduced by nearly 90% when a pulley system was used in lieu of a conventional thruster for a semi-submersible model. Changes in mooring stiffness did not influence the period of resonance response but did affect the magnitude of resonance response, particularly in surge. For a linear horizontal mooring system applied to a semi-submersible model, a 1% decrease in the spring stiffness resulted in a 9% decrease in the magnitude of resonance response for surge, Tr, mag.
Feasibility study of reusing concrete gravity-based foundations designed for tidal energy converters
(University College Cork, 2022) Dineen, Kate; Li, Zili; Ryan, Paraic; European Regional Development Fund
Tidal energy converter devices have been developed to capture the enormous energy potential of the tides. These devices rely on robust mooring and foundation systems to ensure efficient energy extraction in operational conditions, and stability in extreme environmental conditions. Gravity-based foundations (GBF) are currently the most commonly used foundation type within the tidal energy industry. While tidal turbines are typically supported using bespoke carbon-steel tripod structures, concrete gravity-based foundations have been put forward by a number of studies as an alternative support solution. Several novel concrete GBF concepts exist and the developers of such concrete structures state that these foundations may be reused or relocated following decommissioning. Reuse of these massive concrete structures would greatly reduce construction and demolition (C&D) waste, and the need for new concrete GBFs for future devices, thus contributing significantly to the sustainability of the tidal energy industry. However, the concept of reusing concrete gravity-based foundations following long periods of deployment underwater has not been tested in real-world scenarios due to the nascent nature of the industry and long commissioning time periods. As highlighted from a related concept in the oil and gas industry, several safety issues may arise from reusing and relocating concrete GBFs, including geotechnical hazards and concrete degradation due to corrosion. Therefore, this study assessed the practicalities of reusing concrete foundations following decommissioning by designing a concrete GBF from first principles to be used for further analysis. This representative GBF was then extensively tested using Plaxis geotechnical software to investigate soil subsidence and differential settlement, assessing their impact on GBF relocation feasibility. Subsequently, the risk of corrosion to the steel reinforcement in the GBF was examined by, firstly, modelling the chloride concentration profile of the concrete, and secondly, investigating the interrelationship between oxygen availability and water saturation level. Thorough investigation into these study considerations can significantly contribute to the determination of whether it is practicable to reuse or relocate concrete gravity-based foundations in the tidal industry. The findings from the geotechnical analysis supports the possibility of reusing and relocating concrete GBFs for tidal turbines as both the total settlement and the tilt were significantly less than the allowable total settlement and tilt tolerance in a deployment site for which the GBF was designed and a contrasting site for which it was not. However, the findings from the concrete degradation analysis does not support the feasibility of reusing concrete GBFs. A chloride ingress analysis encapsulating three datasets indicated that the critical chloride threshold would be surpassed during a GBFs deployment period, meaning that the protective passive layer on the steel would be compromised leaving it vulnerable to corrosion should sufficient oxygen and water be present.
GEOBIM, BIM integrated geohazard monitoring of at risk slopes and historical retaining structures
(University College Cork, 2022-06-30) Pantoja Porro, Roberto; O'Shea, Michael; Murphy, Jimmy; Geological Survey of Ireland
Over time, structures such as slopes and retaining walls are increasingly deteriorating, resulting in a risk of collapse. Factors such as climate change, human activities, societal development, rapid growth of cities, increasing population and economy make geological disasters occur more frequently than usual. Geological hazards of nature, slope collapse, slope fractures or slope movements have become a problem to be solved by civil engineering. With the advent of low-cost sensors, optical topographic surveying and BIM (Building Information Modelling), such risk could be mitigated and, in some cases, eliminated. The main aim of this research was to use wireless sensors to monitor slopes that are potentially at risk and to incorporate all the information obtained in BIM (Building Information Modelling), in order to make a digitalized vision of the structures in real time. High precision and innovative tools, such as drone flights and slope scanners were utilized for a detailed analysis of the risk of change in the geohazards including soil slopes and historic retaining walls. Through the combination of data from sensors with point clouds generated from drone flights, an early warning system was developed. This early warning system was clearly able to display when there was surface changes therefore highlighting the areas of high risk of collapse. This thesis shows how continuous real-time surveillance of soil slopes and retaining walls can be achieved clearly and concisely, in a cost-effective manner.
High resolution wave and tidal energy resource assessment in the Irish and western UK waters
(University College Cork, 2021-10-19) Furlong, Rebecca; O’Connell, Ross; Murphy, Jimmy; European Regional Development Fund
As island countries, both Ireland and the UK have long and extensive coastlines, making offshore renewable energy easily accessible. Previous studies in the area have shown that there is resource availability for both wave and tidal energy in UK and Irish waters, with an abundant wave resource off the west coast of Ireland and a well-known tidal resource within the Irish and Celtic Seas. The Irish Climate Action Plan 2019 set out that 70% of electricity would come from renewable sources by 2030, meaning that research and development that is ongoing in the offshore industry is key to reaching that target. This study aims to create new, updated GIS layers showing both the wave and tidal energy resource as well as the parameters needed to compute them, including significant wave heights, wave energy periods and tidal current speeds. The Copernicus Marine Service recently updated two models that now contain wave spectrum data at high resolutions, both less than 5 kilometres, and long hindcasts of greater than 20 years. The accessibility of this data means that the wave energy resource can be modelled very accurately at high resolutions, a parameter that is hugely important for marine renewable energy developers to gain an understanding of potential deployment site characteristics. Data for tidal resource analysis is available through the Irish Marine Institute and is based on a ROMS model. This study has shown that the Copernicus models correlate very well with each other, and it is possible to create resource layers for use in GIS with the data. This information is imperative for marine renewable energy developers at a first stage so they can have a thorough understanding of the resource availability and conditions available at a proposed site. Having resource information available within a GIS tool can give developers a spatial overview of where the best resource is available, while the GIS can also provide valuable information such as the location of the closest grid connections and the nature of the underlying bedrock, all factors that can influence the location of a wave or tidal farm.
A methodology and trial implementation for digitising information on a factory floor
(University College Cork, 2019-10-04) Duffy, Annie; O'Sullivan, Dominic; Bruton, Ken; Science Foundation Ireland
In recent years manufacturing industries have moved towards Smart Manufacturing, to achieve improved efficiency and production targets. Part of this innovation of current processes includes digitisation and improving access to machine information, usually through the introduction of new technology to assist with this transition. In order to maintain smooth processes and uninterrupted production, various information sources must be available on the factory floor. This project aims to provide a proof of concept for digitisation and access to necessary information during Pulse Walks. The methodology used to develop this tool is discussed. Observations during Pulse Walks were used to highlight the areas that this could be applied to, and a survey was used to determine the most useful information sources to include. Another aspect of this project is to introduce a method of digitally storing issues discussed during the Pulse Walk, to highlight recurring issues and problematic areas. This was developed to be used as part of the tool during Pulse Walks. This research will present a proof of concept for an app that will act as a digital information hub for accessing information and logging issues from the Pulse Walks. The use cases for this tool have been deliberated and the benefits clearly identified. This tool can assist with tracking recurring issues, using previously logged issues to create a historical database. The issue logging dashboard can be used for investigating reasons for machine downtime. This tool aims to improve production efficiency for a manufacturing line in a factory through issue tracking.
Performance and hull pressure analysis of scaled physical testing of a wave energy converter
(University College Cork, 2022-06) Bevin, Anne; Murphy, Jimmy; O'Shea, Michael; European Regional Development Fund
Wave energy conversion is an emerging field with the potential to capture a significant amount of a globally abundant energy resource to lower reliance on fossil fuels. At present, many designs for wave energy converters are being developed which show great promise for efficiently capturing wave energy. One of the most common barriers to the commercial development and deployment of these devices, however, is the high cost of manufacturing and design validation. The ocean is a harsh environment in which to place infrastructure, and there is a high risk of a wave energy converter being critically damaged at sea after going through a long and costly development process. For this reason, small-scale tank tests and computer modelling of concepts are vital to develop wave energy converter technologies to the highest possible degree before being put into an open-water operational environment. This study describes a physical tank testing campaign of one such model, the Ocean Energy (OE) Buoy, a floating oscillating water column wave energy converter. The walls of the OE Buoy are open to allow water to freely flow through it, and this study seeks to determine whether this might allow for the device to be made with a thinner hull than “closed-container” marine devices. If the water pressure that the hull walls will experience during operation is overestimated in the OE Buoy’s current design, this could have the potential to significantly lower costs of materials and production. This testing was conducted at University College Cork’s Lir NOTF tank facility in November and December of 2021, and the OE Buoy model used is designed at 1:15 scale.
Stakeholder engagement and Irish public perception of offshore wind farms
(University College Cork, 2020-07-31) Cronin, Yvonne; Cummins, Valerie; Wolsztynski, Eric; Mullally, Gerard; Science Foundation Ireland
Public attitude towards onshore wind farm development in Ireland has been extensively investigated, as the sector is a relatively well-established sector in Ireland today. In contrast, currently there is little or no understanding of the perception of the Irish public to offshore wind farms (OSWFs). At this critical juncture in the accelerated development of the offshore wind sector, it is necessary to gauge public opinion regarding offshore wind farms. Of the many challenges associated with the development of the offshore wind industry in Irish waters social acceptance is potentially one of the most significant obstructions. To attain social acceptance of a development, it has become crucial to identify and involve the various stakeholders (at all levels) at the earliest possible stage or expose the project to the possibility of public disputes, opposition and delays. In order to involve stakeholders in any process, the stakeholders must first be identified and then mapped, in order to ascertain their potential influence over the project. These levels of influence of stakeholders, shift and change over the lifetime of the project. There is also a significant difference between the general acceptance of sustainable energy expansion and the acceptance of tangible, proposed renewable energy projects by the general public. Gaining a snapshot of social attitude towards offshore wind development provides a useful tool with which to understanding public opinion regarding offshore wind development. It is also essential information in order to know at what level to pitch a public information campaign regarding offshore wind development. The effect that print media has on attitudes of those who read it has also been shown to be significant. As a result, understanding the framing of the ‘offshore wind development’ message from the print media sector is also crucial in understanding the perception of the Irish public towards the offshore wind farm industry in Ireland. The aim of the research was to understand the many facets of public perception of offshore wind development in Ireland. This study used a mixed methods approach guided by existing studies of the same subject in other jurisdictions. A stakeholder mapping exercise identified stakeholders according to seven categories; government , supply chain, vested interest groups, general public, print media, political representatives, and Non- Governmental Organisations (NGOs). Issues of concern from the perspective of the offshore wind industry were important to understand. These findings influenced the research design for this thesis, which was undertaken as part of the Science Foundation Ireland EirWind project on a blueprint for offshore wind. A national survey was undertaken to develop the first overall picture of the public attitude of the Irish population to offshore wind farms, and their attitude to potential future development. The survey was nationally representative, with 1154 completed questionnaires analysed. Results indicate that attitudes to planned OSWFs change significantly with education levels. Most of those questioned believed that Ireland is too reliant on foreign energy and agreed that Ireland is running out of its limited fossil fuel reserves. The majority of people also believed that the government is not doing enough to reduce carbon emissions and should invest in offshore wind farms. 63% of those surveyed believed that offshore wind farms would increase Ireland’s job creation potential. A clear majority of those who took part in the survey were in favour of offshore wind farms both on a local and national level. Just over half of the participants believed that offshore wind farms are the best solution to our energy situation. Approximately half of respondents had previous experience of offshore wind farms (the majority of whom had experienced offshore wind farms on holiday). To further investigate the perception of those who are regularly exposed to offshore wind farms, a focus group involving members of the public with regular exposure to Ireland’s only wind farm The Arklow Bank, was held. The scope of sentiment expressed towards the offshore turbines ranged from benign to extremely positive. Returning to the results of the national survey; in terms of the effect on wildlife, tourism and aesthetics, respondents found offshore wind farms to be relatively unobtrusive and in general a positive addition to the seascape. The respondents' attitudes towards offshore wind farms was shown to change significantly with their primary source of printed news. As a result, a media content analysis was also conducted to identify arguments used in the presentation of offshore wind to the public, while the sector is at a nascent stage of development. The study revealed Ireland’s offshore renewable industry making slow but consistent progress towards expansion of offshore wind generation with coverage intensifying from 2018. Negative sentiment was perceived with regard to coverage of government action or decisions, which revealed the importance of framing; this is shown in the context of media informing public opinion. In short, this research provides valuable insights into public perception of offshore wind in Ireland, at a time when development is likely to increase significantly. While opposition may be anticipated at a local, project level in the future, a window of opportunity exists to facilitate a national discourse via a public awareness campaign at a national level, supported by government and industry.
The development of a data-driven decision support tool to reduce the energy consumption of a manufacturing process
(University College Cork, 2022-10-07) Morris, Liam; Bruton, Ken; O'Sullivan, Dominic; Horizon 2020
With an ever-growing urgency to reduce energy consumption in the manufacturing industry, process stakeholders need more visibility and insights into how much energy they consume, or can expect to consume, for production. In industry today and with the use of Industry 4.0, the way data is utilised has evolved, with data collection and analysis performed digitally. With many long-established manufacturing processes, the jump from older empirical practices to digitalised practices can be difficult. Similarly, many process stakeholders use process data for different means such as production efficiency improvements. From this it can be difficult to ascertain what information is recorded on machines. And with various machines performing varying tasks in part production, this may drive high energy consumption. One such example is computer numerically controlled (CNC) machining tools. These tools are a common manufacturing apparatus and are known to consume energy inefficiently. This thesis describes the development of a hybrid methodology to identify and select key data features on a CNC machine in medical devices manufacturing. Subsequently, this data is used in an empirical energy consumption model of a CNC machine which enables the energy consumption to be determined from the number of parts processed by the machine. In using a calibrated approach, the data undergoes initial preparation followed by exploratory data analysis and subsequent model development via iteration. During this analysis, relationships between parameters are explored to identify which have the most significance on energy consumption. A training set of 191 data points yielded a linear correlation coefficient of 0.95 between the power consumption and total units produced. Root Mean Square Error, Mean Absolute Percentage Error and Mean Bias Error validation tests yielded results of 0.198, 6.4% and 2.66%, respectively.
Variability in the health and condition of breeding northern gannets (Morus bassanus)
(University College Cork, 2021-01) Fitzgerald, Micheál; Jessopp, Mark John; Lynch, Sharon A.; Department of Agriculture, Food and the Marine, Ireland
Seabird populations are in global decline, with impacts from fisheries and invasive species on seabird mortality being well described. Physiological condition can affect survival and reproductive success at the individual level, but effects of physiological condition at the population level are less well understood. This study identifies patterns of variability in the physiological condition of a population of breeding northern gannets (Morus bassanus) between years, nesting stages, and fasting levels. Blood samples were collected from breeding birds attending chicks in 2018-2020, with blood smears used to quantify blood cell types indicative of chronic stress, infection, disease, and immunocompetence. While no blood parasites were observed, elevated Heterophil to Lymphocyte (H:L) ratios, eosinophils, and monocytes suggest that there was a higher prevalence of infection in 2018 and 2020 than in 2019. Standardised body condition was lowest during early chick-rearing, and chronic stress levels, indicated by high H:L ratio, were elevated in both incubation and early chick-rearing compared to the late chick-rearing stages. Interestingly, birds returning from foraging trips were less stressed than those departing, suggesting an effect of fasting on stress levels. However, sample size was too small to determine whether this difference was statistically significant. This study highlights the value of haematology as a tool for identifying patterns of variability in the health and condition of seabird populations; however further research is needed in order to better understand the processes driving this variation and its effect on populations.
Visual inspection and bridge management
(University College Cork, 2020-10-29) Quirk, Lucy; Murphy, Jimmy; Pakrashi, Vikram
This thesis estimates the impact of visual inspection prior to its implementation in a Bridge Management System (BMS) using Value of Information (VoI). Visual inspection is the principal assessment method for bridge structures, whereby a condition rating is assigned reflecting the structural condition of a bridge, based on the judgements of a trained inspector. The impact of data collected from visual inspection is contingent on its ability to guide towards optimal maintenance decisions throughout the lifecycle to maximise network performance. The VoI concept from Bayesian pre- posterior analysis is defined as the quantification of the reduction of uncertainty in a decision-making problem, after new information is received. This concept has seen multifaceted applications in the optimisation of Structural Health Monitoring techniques, typically focussing on the ability to monitor a specific parameter to determine the degradation rate and condition of a single asset. The merits of visual inspection data have been largely overlooked thus far. This work outlines and applies a framework to put a measure on the impact that visual inspection provides to infrastructure asset managers operating a BMS, and to illustrate how this is influenced by the underlying uncertainties of the model parameters.

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