NUI Maynooth Eprint Archive
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Experimental assessment and validation of energy-maximising moment-based optimal control for a prototype wave energy converter
No full textIn recent years, a framework for control of wave energy converters (WECs), termed moment-based control, has been developed within the wave energy conversion literature, exhibiting a remarkable performance in terms of energy absorption, while retaining real-time computational capabilities. Nonetheless, to date, practical results regarding moment-based control for WEC systems have been exclusively provided in numerical simulation, i.e. there is currently a lack of ‘real-world’ assessment of this promising control framework. Motivated by this, we present, in this paper, an experimental assessment and validation of moment-based WEC control for a prototype Wavestar wave energy converter, at the tank-testing facilities of Aalborg University, Denmark. In particular, we address the control design and synthesis procedure in an integrated fashion, covering experimental (physically consistent) system identification, unknown-input estimation and forecasting of wave excitation force, and subsequent control law implementation. We demonstrate that the moment-based controller is able to effectively maximise energy absorption from the wave resource in real-time, with a significant and consistent improvement with respect to the defined benchmark case. The results presented and discussed in this paper demonstrate the feasibility of moment-based WEC control, filling the gap between the attractive theoretical aspects associated with such a strategy, and the practical WEC energy conversion application
Continuity, change and new ways of being: An exploratory assessment of farmer's experiences and responses to public health restrictions during the COVID‐19 pandemic in a rural Irish community
No full textFarming occupations are, in the Global North, generally solitary, and a growing body of research identifies this as one of the factors that underpins low levels of wellbeing and poor mental health amongst farmers. The primary public health response to the coronavirus disease 2019 (COVID-19) pandemic focused on reducing transmission of the virus by limiting interactions of people. This article seeks to assess the impact of these restrictions on farmer's experience of isolation and how it shaped their wellbeing. Applying a broad socio-ecological framework, we analyse change, continuity and shifts in social and economic relations and their spatial reconfiguration during the COVID-19 pandemic as recounted in semi-structured, qualitative interviews. We found that while COVID-19 has disrupted socio-spatial relations, including key sites of socialisation for farmers and rural communities, occupational isolation was viewed as a positive feature of farming as was working in nature. Familial and informal networks of support were important throughout the pandemic, while novel engagements with communication technologies facilitated both change and continuity of social and economic interaction. Whilst these findings are broadly positive, the reconfiguration of, particularly, economic relations is viewed as accelerating the turn towards service delivery using technology and, consequently, further reducing opportunities for social interaction. © 2023 The Authors. Sociologia Ruralis published by John Wiley & Sons Ltd on behalf of European Society for Rural Sociology
Experimental assessment of an unknown-input estimator for a nonlinear wave energy converter
No full textIn the wave energy field, one of the main challenges towards commercialisation of wave energy devices is the development of suitable control laws, able to maximise the absorbed energy while guaranteeing effective satisfaction of any required physical constraint. However, one of the main characteristics of this optimal control problem is that the system behaviour is strongly influenced by the external (uncontrollable) input arising from the wave source, i.e. the wave excitation, which is often unmeasurable. As such, computation of optimal control solutions for WEC systems requires availability of instantaneous knowledge of the wave excitation, and hence input-unknown estimators are developed within the control loop. State-of-the-art estimation strategies are based on the knowledge of control-oriented linearized models of the system, often neglecting the influence of nonlinear phenomena within the system description. We propose, in this paper, an approach inspired by disturbance observer-based control, able to accommodate well-known hydrodynamic nonlinear effects in the process of estimating the unknown excitation force acting on the device. This strategy, which in contrast to the usually applied estimators does not require an implicit/explicit model of the wave excitation force, is tested on a hardware-in-the-loop facility in different sea state conditions, to realistically assess its performance in terms of estimation error and delay. The experimental appraisal show satisfactory results in terms of normalized root mean square error and average delay, which, together with the simplicity of the method, positions the proposed strategy as a promising candidate for hardware implementations in real environments
Long term wave load trends against offshore monopile structures: A case study in the Bay of Biscay
No full textThis study examines the trend in wave parameters over available annual records in the Bay of Biscay, where EWTEC
2023 is being hosted. There have been various renewable offshore energy projects in the 21st century in this region,
such as the OWC (Oscillating Water Column) plant in Mutriku [1], or BiMEP (Biscay Marine Energy Platform)[2],
the infrastructure for testing ocean devices in Armintza, where better characterization of the wave resource could help
to provide design information to developing wave energy technology. Other studies [3] have shown that wave height
has increased in recent decades, as well as the frequency at which extreme waves occur, which affects the fatigue
experienced by deployed devices. The aim is to study the effect of the maximal wave height, its frequency, and loads
on monopile cylindrical structures, which are basic component structures for wave energy converters and offshore
wind turbines. The effect of this evolution, against these generic structures in offshore wind and wave energy devices,
is studied using the 20th century reanalysis ERA20 (1900-2010) of ECMWF (European Centre for Medium-Range
Weather Forecasts) [3]. A significant increase in two forces, drag forces and inertial forces, of up to 15%, is computed
over 110 years at a gridpoint near the Western Basque coast, which constitutes a strong positive slope that can be also
associated with climate change, and has strong implications for the design of new marine renewable energy technology
Factor Structure of the Shortened Six-Item Version of the de Jong Gierveld Loneliness Scale (DJGLS-6) : A Systematic Review and Testing Factor Models in a Nationally Representative Sample
No full textIntroduction: Loneliness is linked to negative physical and mental health
outcomes. Therefore, it is important to employ reliable and valid screening measures for early detection and treatment. A widely used scale for assessing loneliness is the shortened six-item Jong Gierveld Loneliness Scale
(DJGLS-6).
Aims: To review and evaluate the factor structure of the DJGLS-6.
Methods: Study 1 was a systematic review. To examine the factor structure of the DJGLS-6, peer-reviewed studies were reviewed in accordance
with PRISMA guidelines. Study 2 tested the factor analytic models found
in Study 1. Confirmatory factor analysis (CFA) was performed using data
from a nationally representative sample of adults to assess the latent structure of the six-item scale.
Results: In Study 1, findings from the two papers reviewed suggested that
the scale measures two correlated dimensions: social and emotional loneliness. This finding was consistent with the results of Study 2. However, the
fit statistics for the one and two-factor CFA models were not acceptable.
Modification indices indicated that adding a cross-factor loading to allow
item 2 (“I miss having people around”) of the social loneliness factor, to
load on both the emotional and social factor, to load on both the emotional
and social factors would significantly improve the fit of the model.
Conclusions: The analysis failed to support previous findings concerning
the robustness of the subscales. We recommend performing future evaluations of the scale and for the authors to consider changing item 2 accordingly
A Tale of Two Sisters: Social movement mobilisations in response to acts of violence against women in Argentina and Ireland.
No full textOne in three women globally will experience violence in their lifetime: violence against women (VAW) is a multi-layered human rights issue. This research internationalises the social movement perspective and employs a ‘political process’ approach to compare two social movement organisations (SMOs), the Argentinian SMO, Ni Una Menos (not one (woman) less) and the Irish SMO, ROSA (for Reproductive Rights, against Oppression, Sexism and Austerity). Both are currently engaged in mobilisations seeking radical social transformation, with a strong focus on eliminating VAW. Theoretically, pivotal moments in the struggle can be best understood through an analysis of the interaction of political opportunities, mobilising structures and framing processes. This research focuses on two national pivotal protests in Argentina and in Ireland, when these SMOs identified a political opportunity, and by utilising both traditional and digital mobilising structures shaped their ‘framing processes’ in response to VAW. This is achieved through the analysis of social media platforms utilised during these pivotal protests and interviews with members of both SMOs. This analysis makes a contribution to understanding how political opportunities shape mobilisations and rely on strong mobilising structures and resonant framing strategies in achieving concrete political outcomes
Challenging the pixels of power: A critical inquiry into police use of facial recognition technology through the lens of surveillance studies
No full textThe increasingly prevalent roll out of surveillance-focused technological tools by law
enforcement worldwide has the ability to alter the practice of policing as we know it. Therefore,
understanding the potential ramifications of implementing such technology into the criminal
justice space is imperative. This dissertation employed a comparative case study analysis to
examine the adoption of facial recognition technology by police agencies and its possible
implications via the assistance of a surveillance studies lens. The study focused on two distinct
police agencies located in different jurisdictions, these were: New York City Police Department
(United States) and the London Metropolitan Police (United Kingdom). The examination of FRT
use in these separate law enforcement organisations addresses key questions surrounding the
technology’s justification and surveillance motivations underpinning its explosion amongst law
enforcement organisations. An extensive analysis of secondary sources was conducted, including
existing policies and regulations, media and news articles, academic journals and when available,
governmental, civil liberty and other interest group publications. The results of this research
reveal the multifaceted dynamics that influence the adoption and operation of facial recognition
technology by the police and provides a critical insight into the tensions between security
objectives, the safeguarding of civil liberties and the relationships between corporations and law
enforcement. The findings of this study contribute to the already existing research on the
complexities of facial recognition technology in the policing context and underscores the need
for transparent and informed dialogue as societies navigate the evolving landscape of
technology-driven surveillance
COVID-19 infections and short-run worker performance: Evidence from European football
No full textCOVID-19 infections represent a recurrent source of workplace absenteeism impacting labour productivity. Using
a unique matched employee-employer dataset, we consider the effects of the virus on the performance of highly
valuable employees when returning to work: professional footballers in the top five European leagues. This offers
a window to study job scheduling and managerial decision-making. We employ a difference-in-differences (DiD)
model that compares the performance of infected players to a matched control group for game tasks that require
physical exertion. Results suggest that per-minute performance is unaffected upon returning to play. This is likely
due to effective management of minutes on the pitch. We carry out a battery of checks on the primary results to
consider causal mechanisms outside of infection that could impact the results such as lockdown breaks, clusters
within squads, and scheduling effects. The findings carry an optimistic message and specifically speak to managers supervising physical labour. If appropriately managed, infected workers can return to past performance
levels
John Scottus Eriugena (c. AD 815–877) and the Charge of Pantheism: A Theological and Historical Investigation
No full textTo this day, general discussion on the ninth-century Irish scholar John Scottus Eriugena
regularly turns to the topic of pantheism, that is, the identification of God with the world. His
major theological work, the Periphyseon, was condemned in AD 1225, and affirmations of its
having a pantheistic outlook have continued into more recent times. The present study grew
from a desire to be able to understand the matter with a greater degree of insight, and to
present findings which might add to the expanding tradition of Eriugena studies. The object
of the dissertation, therefore, is to examine the content of his work for the presence of
pantheism, not just with regard to the historical context of its condemnation, but on its own
merit
Integration as Making Place
No full textIn this paper, we provide a new approach to defining and operationalizing integration as “making place.” We distinguish between making place for – a process of accommodation – and making place with – a process of
co-production. We emphasize the potential of making place with as an alternative to top-down definitions of integration, and show this in practice through our research with migrants and migrant-supporting organizations
in the Republic of Ireland. We conclude that making place with offers new insights into integration as processual, relational and practice-based, thus enhancing our understanding of migration and migrant experiences across
diverse socio-spatial contexts