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Sampling designs for the spatiotemporal modelling of groundwater quality monitoring data
Get PDFApplying appropriate sampling designs in the long-term monitoring of groundwater quality networks is crucial in ensuring that accurate inferences are made about the spatio-temporal distribution of the concentrations of constituents of potential concern (CoPC). Furthermore, the sampling of groundwater monitoring wells and the subsequent analysis of samples induces costs, safety hazards and unintended environmental consequences. Therefore, an optimal sampling design should aim to minimise sample sizes, whilst maximising the value of the information obtained. The problem of finding optimal locations for wells to extend or establish a network has received a lot of attention in the literature. In contrast, fewer approaches have been proposed for optimal sample selection within existing networks, especially in a spatio-temporal context, and the application of these approaches in practice is limited. Current sampling practices often rely on expert judgment and prescriptions by regulatory bodies, which results in datasets that are not well-suited for statistical analysis. Despite its statistical advantages such as generalisability and reducing bias, probability sampling is seldom applied in long-term groundwater quality monitoring. The primary aims of this thesis were to assess common characteristics of long-term groundwater quality data and the use of spatio-temporal models, explore the optimisation of sampling designs through reducing network size, and propose approaches based on probability sampling to support the spatio-temporal modelling of CoPC concentrations.
To compare different approaches to the spatio-temporal modelling of CoPC concentrations via generalised additive models (GAMs) and to assess common characteristics of long-term ground water quality monitoring data, a comparative study is presented. The study uses synthetic and case study data to evaluate differences in estimating spatio-temporal CoPC concentration surfaces via GAMs with separate and joint smooth terms for space and time. The results highlight the importance of model specification and sampling patterns for obtaining reliable estimates of CoPC concentrations.
In practice, the identification of wells that provide redundant information with respect to the estimation of CoPC concentrations can often be omitted from sampling designs to reduce strain on resources, whilst ensuring that conclusions about spatial and temporal trends are not affected. The demand for a tool to facilitate well redundancy analysis was identified through feedback shared by the users of the groundwater quality modelling software GWSDAT1. In this thesis, a computationally efficient, data-driven approach is proposed for ranking monitoring wells based on their influence on spatio-temporal CoPC concentration models. The approach is based on influential observation diagnostics and is shown to provide rankings similar to a computationally more demanding, cross-validation (CV) based method, through a case study and a simulation study using synthetic groundwater quality data. The approach has also been implemented in GWSDAT.
Thus, omitting redundant wells can be an effective approach for the optimisation of groundwater monitoring networks, but it does not make suggestions on specific sample selection. The generation of spatio-temporal sampling designs, optimised to support the estimation of CoPC concentrations, can help further improve the sustainability of long-term monitoring. In this thesis, it is shown through a literature review that probability sampling designs that aim to draw a spatially and temporally balanced, i.e. evenly spread samples, result in a more precise estimation of CoPC concentration surfaces than simple random designs. Furthermore, it is proposed that by tuning the inclusion probabilities of sample units in balanced designs based on historic data to track the spatial evolution of CoPC concentrations through time, a more precise characterisation of the CoPC plume can be achieved. An original, data-driven methodology is developed for tuning sample inclusion probabilities to be proportional to future predicted distances between the wells and the boundaries of the CoPC plume. Higher probability for selection is given to wells that are predicted to be closer to the plume at a given time. The proposed methodology is shown to provide advantages in characterising plumes given a sufficiently large sample size, using a case study and a simulation study of synthetic CoPC concentration data.
An approach is also proposed for the application of spatio-temporally balanced sampling designs in evaluating the sufficiency of historic sampling intensity. By comparing the CoPC concentration estimates of models using all available historic data and increasingly smaller subsamples selected via balanced designs, it can be assessed whether the monitoring network has been over or undersampled. This information can then be used to adjust future sampling intensity accordingly.
Finally, consideration is given to the trade-off between high spatial and temporal sampling intensity, given a fixed sample size and monitoring period. In practice, it can be logistically advantageous to perform sampling less frequently, but obtain more samples during each campaign. This results in a spatially high, but temporally low resolution data set. Through a simulation study of synthetic CoPC plume data, it is shown that high spatial resolution data is advantageous when estimating the overall concentration surface, but high temporal resolution data can provide benefits in estimating plume characteristics
The interaction of institutional history & policy in digital technology for audience engagement: a case study of Glasgow Museums, 1990-2022
Get PDFUnderstanding the ways in which digital technologies can support audiences is imperative to museums’ functioning in a world where the digital and non-digital are enmeshed. As museums often find themselves short on resources with strong demand pressures to use digital technologies to address issues like access, this becomes increasingly important. Historic institutionalism as well as institutional policies and values are critical to such approaches. They frame the broader adoption and understanding of technologies in relation to engagement practices. Related subject matter has been addressed disparately in both academic literature and professional disciplines ranging between cultural policy, museology, digital engagement evaluation, and museum management. These fields rarely draw from one another and there are few examples of longitudinal studies of digital integration in museums, let alone the overlap between participatory practices employing digital technologies in this regard. Accordingly, this transdisciplinary study attempts to provide insight by linking these fields. It does so through a situated case study following Glasgow Museums over two decades (1990-2011) with further consideration of their most recent capital project, the Burrell Collection (2022). The research aims to examine how audience engagement has been supported by an evolving understanding, development and use of digital technologies in the museum service. This is underpinned by three questions: 1) what key factors have shaped the approach to audience engagement; 2) what role has digital technology played in this; 3) how these factors have shaped the use of interactive digital technology in support of meaningful engagement.
The methodology used to study this included qualitative methods like interviews and close text readings that were abductively analysed for emerging themes. Through a longitudinal analysis centring three critical junctures in the service’s history, several key factors were found to have significant impact on Glasgow Museum’s approach to audience engagement and digital technologies. Most significant were factors that centred organisational values of access and inclusion; leadership support therein; awareness of the local audience-community context; external policy context; resource availability; practical application of values; insufficient digital literacy and skills; lack of space for creativity. Notably, it was the role of institutional history, policy and values in shaping audience engagement practices. Digital technology was never foregrounded for this aim, but instead a parallel factor. The research generates a suite of recommendations in consideration of museums’ situated contexts, with its findings contributing to broader understanding on how museums can incorporate digital technologies for generating meaningful audience engagement
Interart mediations: Between text and image in the works of Mallarmé and Whistler
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Management control for risk management in the public sector: a levers of control perspective
Get PDFThis thesis investigates the integration, or the interaction and influence, of risk management tools with management control systems and vice versa, within the Greek public sector. It employs the Levers of Control (LOC) framework (Tessier and Otley, 2012), to examine how these two processes are integrated and influence each other in practice, in contemporary public sector risk management. This is done in an effort to reconcile previous literature that recognises this integration but requires more evidence on their practice (Bracci et al., 2022). Hence, this study addresses a gap in the existing literature by providing empirical insights into how management control systems deployed in public sector risk management, and how they interact with each other to form response to an organised uncertainty. Through this integration, this study also unravels how management control systems are utilised to make sense of emergent risks, in an effort to answer the calls to better understand the connection of management control and risk management (Bhimani, 2009; Soin et al., 2013). Specifically, it examines the case of a Greek public sector organization responsible for overseeing projects funded by the European Union. This organisation has a well-designed and implemented risk management system, that interacts with various controls tools to build a holistic approach to managing risk. Through the revised Levers of Control framework (Tessier & Otley, 2012), it was evident that risk affects the design and function of control systems at all organisational levels, with performance management being central in that effort. Moreover, various control tools were used interactively to induce knowledge and graphically depict uncertainty
The geochronology of plutonism associated with the Great Glen Fault, northern Scottish Highlands
Get PDFThe Northern Highlands of Scotland contain Palaeozoic intrusions emplaced during collision of continents Baltica and Laurentia of the late Caledonian Scandian Orogeny. However, uncertainties remain regarding the accuracy of existing isotope dilution geochronology and understanding of the geodynamic history in relation to spatial and temporal distribution of intrusions. This study obtained emplacement dates by zircon U-Pb LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) for the Strontian intrusion Sunart facies (423.5 ± 2.1 Ma), Strontian Sanda facies (418.2 ± 6.3 Ma), Helmsdale intrusion (417.0 ± 4.0 Ma) and Abriachan intrusion (418.2 ± 5.6 Ma). These dates provide confidence in existing literature, and a new date for the Abriachan intrusion. Further, use of in situ analysis produced evidence of antecrystic zircon and thus pre-emplacement magmatism in each sample up to a maximum age of c. 450 Ma, supportive of the lower crustal hot zone model for late Caledonian magmatism in the Northern Highlands. LA-ICP-MS zircon trace element data obtained for the Strontian Sunart facies similarly support open system magma evolution and homogenisation within a lower crustal hot zone prior to emplacement.
Spatially limited mid – upper crustal emplacement and thus limited mobilisation of hot zone material from c. 450 – c. 432 Ma is attributed to compression in the Laurentian margin induced by the initial stages of continental collision. Widespread mid – upper crustal emplacement from c. 432 – c. 423 Ma typically associated with regional transpression is interpreted as comprising new mantle derived melt and remobilised hot zone material. This widespread emplacement may have been triggered by lithospheric delamination, particularly the peak in emplacement at c. 425 Ma. A final phase of emplacement of evolved magmas is defined at c. 418 – c. 417 Ma and is highly spatially limited to the Great Glen Fault and related faults. This phase is interpreted to comprise remobilised hot zone material emplaced during a phase of strike slip displacement and may be related to continued uplift and the accretion of peri-Gondwanan terranes to Laurentia further southwest
Wireless intelligent distributed consensus system for autonomous driving
Get PDFThe rapid advancements in embedded processing, sensing, artificial intelligence (AI), and communication technologies have accelerated the adoption of connected and autonomous systems (CAS). However, as devices in CAS become more intelligent and autonomous, their application scenarios—such as autonomous driving—are growing increasingly complex and dynamic. To enable intelligent, connected, and autonomous (ICA) nodes to engage in deeper deliberation and mutual understanding, joint decision-making has emerged as an effective solution. Joint decision-making is a process where multiple autonomous agents collectively analyze information, deliberate, and reach consensus to make unified decisions that align with common goals. However, traditional joint decision-making approaches face significant challenges when applied to the stringent demands of modern CAS. For instance, centralized decision-making (CDM) offers streamlined processes and high consistency but suffers from limitations like single points of failure (SPOF), scalability issues, and dependence on centralized infrastructure. By contrast, the decentralized nature of distributed decision-making (DDM) enhances scalability and system reliability, leveraging the intelligence of individual nodes to achieve collective intelligence, making it a promising alternative. In this context, distributed consensus (DC) protocols as a key element in distributed systems are essential to enabling DDM, with features such as data consistency and fault tolerance drawing significant research attention in recent years. This thesis focuses on the application, optimization, and development of wireless DC protocols to enable ICA nodes in CAS, with a particular focus on autonomous driving, to achieve robust and expressive joint decision-making.
First, the study proposes Intelligent Distributed Consensus (IDC) and introduces the first IDC protocol, Intelligent-Raft, which builds upon the traditional Raft algorithm. Additionally, to facilitate the deployment of IDC in practical CAS environments, the study introduces Wireless Intelligent Distributed Consensus System (WIDCS) which leverages distributed wireless communication combined with the Intelligent-Raft algorithm to enable ICA nodes to make collective joint-decisions and ensure fault tolerance. A practical hardware module of WIDCS is implemented using microcontroller-based systems, which is named ‘AIR-RAFT’. To validate the feasibility and effectiveness of WIDCS, we undertake research and evaluations within an autonomous driving scenario, specifically at uncontrolled intersections, utilizing both mathematical modeling and practical scenario testing. Numerical and experimental results, in good alignment, demonstrate that WIDCS substantially improves autonomous driving safety
Second, this study enhances WIDCS by incorporating the functions of ad hoc network formation, management, and dismissal, improving its ability to provide better data consistency and joint decision-making services for ICA nodes. Additionally, we have developed the second-generation WIDCS module, RaBee, which enables distributed nodes to achieve Intelligent-Raft consensus via a ZigBee-based ad hoc network. In addition, we develope mathematical probability models to evaluate and compare the reliability of centralized decision-making systems and WIDCS. Employing autonomous driving in onramp merging as a case study, we further formulated a mathematical model to assess the safety of Autonomous Vehicles (AVs) under different decision-making frameworks. By integrating the RaBee module with AV, we conduct safety tests in practical on-ramp scenarios, and the results demonstrate that WIDCS notably enhances AV safety, indicating substantial potential for future CAS.
Third, this study proposes a novel IDC protocol, Converging-Raft, which leverages the collective intelligence of all nodes to make globally optimal joint decisions—a capability not present in Intelligent-Raft. To enhance the adaptability, we propose the Heterogeneous Intelligent Joint Decision System (HIntS), an architecture which integrates CDM, Intelligent-Raft, and Converging-Raft within a hybrid network combining ad hoc and cellular networks. Our self-developed hardware module at the core of HIntS, ‘5G-MInd’, is designed to verify the system’s feasibility and performance in practical experiments. We develop a mathematical model to analyze and compare the reliability and latency of HIntS under different working modes and validate these findings through joint-decision experiments using 5G-MInd modules. Our quantitative and qualitative results demonstrate the advantages and characteristics of different combinations of joint-decision mechanisms and network structures. These findings highlight HIntS’s adaptability to complex, dynamic environments and provide critical guidance for the practical deployment of future wireless joint-decision mechanisms
A theological study of hyper-Calvinism in the writings of Joseph Hussey (1660-1726), John Skepp (1675-1721), John Gill (1697-1771), and John Brine (1703-1765)
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Numerical investigation of novel rotorcraft propulsion systems
Get PDFIn recent years, an upsurge in advanced air mobility (AAM) aircraft can be noticed worldwide, e.g. , Rolls Royce, Airbus, NASA, DARPA, Advanced Aircraft Company, Bell Helicopter, Aurora, Honeywell, and others. Future AAM will operate near the ground in the urban area, and thus it should be environmentally and community-friendly while maintaining excellent aerodynamic performance. As is known, a high-intensity of sound is emitted by the VTOL aircraft, but noise emission is crucial in the VTOL aircraft certification process and urban operation. It is clear that the propulsors are generating most of the noise from the whole aircraft. Therefore, there is a growing demand for low-noise emission propulsors, reduced wake interference, and improved aerodynamic performance. Previous works show that distributed and wingtip mounted propulsion systems are promising candidates as a novel compact propulsor with excellent performance. However, the combination of multiple sources of lift and thrust brings significant challenges in terms of aerodynamic interactions, noise emissions, vibration, instability, control, trim difficulties, power allocation, and others. Nevertheless, AAM research is emerging mainly in Europe, the USA, and Asia, as the appeal for better civil rotorcraft is growing. Several demonstrators, e.g. the US DARPA XV-24A, Joby S4, and the VX4 from Vertical Aerospace, have been delivered, illustrating the superior performance of AAM aircraft. Ahead of routine deployment of AAM aircraft, there is still significant aerodynamic/aeroacoustic research and development to be carried out.
This thesis aims to investigate novel propulsion concepts, including tip mounted propellers and distributed propulsion systems, through CFD verification, optimisation, and aerodynamic performance evaluation. The first part of the study validates the employed multi-fidelity simulation methods using experimental data from the NASA Workshop for Integrated Propeller Prediction (WIPP) and the Folding Conformal High Lift Propeller (HLP) project for isolated and installed cases under various conditions. Additionally, aerodynamic and aeroacoustic validation via the hybrid methods for rotor-rotor interactions was also conducted using the GARTEUR Action Group 26 measurements.
Applying the same methods and simulation strategies used in the validation, the thesis further examines a series of installed propeller configurations with actuator disks to identify performance differences based on their position relative to a lifting wing. The reduced-order method was cost-effective and suggested the approximate optimal position of the distributed propellers. The actuator disk method has successfully captured the leading-edge suction induced by inflow. In addition, the performance of the propulsion system changes due to different installation effects. Furthermore, additional surfaces from nacelle and pylon structures will also have an impact on the propulsion system. Therefore, additional verification cases utilising high-fidelity methods were carried out, and the investigation of the conventional tractor and the optimal over-the-wing (OTW) configurations was conducted for different numbers of propellers and conditions.
Wingtip-mounted propellers are known to be a promising configuration for reducing induced drag through favourable wake interactions. This thesis presents, for the first time, the integration of wingtip-mounted propellers with an OTW distributed propulsion (DP) system, investigated using high-fidelity, fully resolved simulations. To investigate this novel tip-mounted propeller–distributed propulsion (TMP-DP) configuration, equivalent-performance propulsion systems were proposed based on realistic aircraft operational conditions. The study examines complex interactional flow phenomena inherent to such systems, including propeller–wing, propeller–propeller, propeller–slipstream, and propeller–wake interactions. Given the intricacy of the distributed propulsion setup, key aerodynamic and propulsive parameters, such as thrust and power distribution, wing lift, drag, lift-to-drag ratio (L/D), and pitching moments, are thoroughly analysed and reported.
To harness the benefits of multirotors in a distributed propulsion system, synchrophasing has been implemented as a means of reducing noise. Tandem rotors, with and without vertical offset, are investigated using fully resolved simulations under both hover and edgewise flight conditions. A comprehensive synchrophasing study reveals varying levels of cumulative rarefaction and compression effects in the resulting acoustic waves. To better account for the relative loudness as perceived by the human ear, A-weighting and one-third octave band analysis have been employed. These approaches help to identify how different frequency components contribute to the overall acoustic signature and can inform targeted noise control and mitigation strategies. Finally, this study quantifies noise reductions across the frequency spectrum for each synchrophasing case and identifies the most effective phase angles. These optimal phase configurations can be tuned to achieve maximum noise reduction at specific observer locations
Navigating collaborative networks: reflections on collective impact
Get PDFAt a time in which children’s services in Scotland are increasingly focussed on the rights of the child, recent challenges to children’s education, health and wellbeing have been identified (Goldhagen et al., 2020). Threats such as inequities, violence, globalisation, and climate change combine with entrenched social, economic, and cultural factors to impact children’s lives in complex ways. To mitigate such challenges professionals in educational and children’s services are encouraged to develop collaborative approaches, to embed children’s rights across Scotland (Scottish Government, 2017a). However, despite a plethora of definitions, collaboration remains a contentious term, one that is vague and highly variable (D’Amour et al., 2005). This study aimed to explore how collaboration is understood at the local level and identify how it plays out in practice, providing greater clarity for practitioners and policymakers as they seek to work together to ensure children’s rights are realised.
The study focussed on Local Coordinators within the Children’s Neighbourhoods Scotland programme, who were responsible for developing collaboration across services in local areas (CNS, online). Through a series of interviews and focus groups, participants were encouraged to reflect on their experiences of collaboration. Adopting a mixed methods research design, the study combined social network analysis with activity theory, drawing out qualitative understandings of participants’ experiences (Murphy et al., 2019). Findings indicated that despite the geographical, relational and contextual differences in their experiences, several commonalities could be identified. Participants had to survey the network of services available in their local areas, before then attempting to integrate within and subsequently influence those networks. They also had to understand the broader context in which the collaborative activity was expected to occur whilst navigating additional constraints. The study demonstrates how individuals obtain positions of influence within established networks and bounded collaborative communities
CO2 mineralization of legacy paper mill sludge and its pollution implications
No full textAbstract not currently available
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