3,518 research outputs found

    Undergraduate Catalog of Studies, 2023-2024

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    Geodetic monitoring of complex shaped infrastructures using Ground-Based InSAR

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    In the context of climate change, alternatives to fossil energies need to be used as much as possible to produce electricity. Hydroelectric power generation through the utilisation of dams stands out as an exemplar of highly effective methodologies in this endeavour. Various monitoring sensors can be installed with different characteristics w.r.t. spatial resolution, temporal resolution and accuracy to assess their safe usage. Among the array of techniques available, it is noteworthy that ground-based synthetic aperture radar (GB-SAR) has not yet been widely adopted for this purpose. Despite its remarkable equilibrium between the aforementioned attributes, its sensitivity to atmospheric disruptions, specific acquisition geometry, and the requisite for phase unwrapping collectively contribute to constraining its usage. Several processing strategies are developed in this thesis to capitalise on all the opportunities of GB-SAR systems, such as continuous, flexible and autonomous observation combined with high resolutions and accuracy. The first challenge that needs to be solved is to accurately localise and estimate the azimuth of the GB-SAR to improve the geocoding of the image in the subsequent step. A ray tracing algorithm and tomographic techniques are used to recover these external parameters of the sensors. The introduction of corner reflectors for validation purposes confirms a significant error reduction. However, for the subsequent geocoding, challenges persist in scenarios involving vertical structures due to foreshortening and layover, which notably compromise the geocoding quality of the observed points. These issues arise when multiple points at varying elevations are encapsulated within a singular resolution cell, posing difficulties in pinpointing the precise location of the scattering point responsible for signal return. To surmount these hurdles, a Bayesian approach grounded in intensity models is formulated, offering a tool to enhance the accuracy of the geocoding process. The validation is assessed on a dam in the black forest in Germany, characterised by a very specific structure. The second part of this thesis is focused on the feasibility of using GB-SAR systems for long-term geodetic monitoring of large structures. A first assessment is made by testing large temporal baselines between acquisitions for epoch-wise monitoring. Due to large displacements, the phase unwrapping can not recover all the information. An improvement is made by adapting the geometry of the signal processing with the principal component analysis. The main case study consists of several campaigns from different stations at Enguri Dam in Georgia. The consistency of the estimated displacement map is assessed by comparing it to a numerical model calibrated on the plumblines data. It exhibits a strong agreement between the two results and comforts the usage of GB-SAR for epoch-wise monitoring, as it can measure several thousand points on the dam. It also exhibits the possibility of detecting local anomalies in the numerical model. Finally, the instrument has been installed for continuous monitoring for over two years at Enguri Dam. An adequate flowchart is developed to eliminate the drift happening with classical interferometric algorithms to achieve the accuracy required for geodetic monitoring. The analysis of the obtained time series confirms a very plausible result with classical parametric models of dam deformations. Moreover, the results of this processing strategy are also confronted with the numerical model and demonstrate a high consistency. The final comforting result is the comparison of the GB-SAR time series with the output from four GNSS stations installed on the dam crest. The developed algorithms and methods increase the capabilities of the GB-SAR for dam monitoring in different configurations. It can be a valuable and precious supplement to other classical sensors for long-term geodetic observation purposes as well as short-term monitoring in cases of particular dam operations

    Flood dynamics derived from video remote sensing

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    Flooding is by far the most pervasive natural hazard, with the human impacts of floods expected to worsen in the coming decades due to climate change. Hydraulic models are a key tool for understanding flood dynamics and play a pivotal role in unravelling the processes that occur during a flood event, including inundation flow patterns and velocities. In the realm of river basin dynamics, video remote sensing is emerging as a transformative tool that can offer insights into flow dynamics and thus, together with other remotely sensed data, has the potential to be deployed to estimate discharge. Moreover, the integration of video remote sensing data with hydraulic models offers a pivotal opportunity to enhance the predictive capacity of these models. Hydraulic models are traditionally built with accurate terrain, flow and bathymetric data and are often calibrated and validated using observed data to obtain meaningful and actionable model predictions. Data for accurately calibrating and validating hydraulic models are not always available, leaving the assessment of the predictive capabilities of some models deployed in flood risk management in question. Recent advances in remote sensing have heralded the availability of vast video datasets of high resolution. The parallel evolution of computing capabilities, coupled with advancements in artificial intelligence are enabling the processing of data at unprecedented scales and complexities, allowing us to glean meaningful insights into datasets that can be integrated with hydraulic models. The aims of the research presented in this thesis were twofold. The first aim was to evaluate and explore the potential applications of video from air- and space-borne platforms to comprehensively calibrate and validate two-dimensional hydraulic models. The second aim was to estimate river discharge using satellite video combined with high resolution topographic data. In the first of three empirical chapters, non-intrusive image velocimetry techniques were employed to estimate river surface velocities in a rural catchment. For the first time, a 2D hydraulicvmodel was fully calibrated and validated using velocities derived from Unpiloted Aerial Vehicle (UAV) image velocimetry approaches. This highlighted the value of these data in mitigating the limitations associated with traditional data sources used in parameterizing two-dimensional hydraulic models. This finding inspired the subsequent chapter where river surface velocities, derived using Large Scale Particle Image Velocimetry (LSPIV), and flood extents, derived using deep neural network-based segmentation, were extracted from satellite video and used to rigorously assess the skill of a two-dimensional hydraulic model. Harnessing the ability of deep neural networks to learn complex features and deliver accurate and contextually informed flood segmentation, the potential value of satellite video for validating two dimensional hydraulic model simulations is exhibited. In the final empirical chapter, the convergence of satellite video imagery and high-resolution topographical data bridges the gap between visual observations and quantitative measurements by enabling the direct extraction of velocities from video imagery, which is used to estimate river discharge. Overall, this thesis demonstrates the significant potential of emerging video-based remote sensing datasets and offers approaches for integrating these data into hydraulic modelling and discharge estimation practice. The incorporation of LSPIV techniques into flood modelling workflows signifies a methodological progression, especially in areas lacking robust data collection infrastructure. Satellite video remote sensing heralds a major step forward in our ability to observe river dynamics in real time, with potentially significant implications in the domain of flood modelling science

    Undergraduate Catalog of Studies, 2023-2024

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    Tinto: Multisensor Benchmark for 3-D Hyperspectral Point Cloud Segmentation in the Geosciences

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    The increasing use of deep learning techniques has reduced interpretation time and, ideally, reduced interpreter bias by automatically deriving geological maps from digital outcrop models. However, accurate validation of these automated mapping approaches is a significant challenge due to the subjective nature of geological mapping and the difficulty in collecting quantitative validation data. Additionally, many state-of-the-art deep learning methods are limited to 2-D image data, which is insufficient for 3-D digital outcrops, such as hyperclouds. To address these challenges, we present Tinto, a multisensor benchmark digital outcrop dataset designed to facilitate the development and validation of deep learning approaches for geological mapping, especially for nonstructured 3-D data like point clouds. Tinto comprises two complementary sets: 1) a real digital outcrop model from Corta Atalaya (Spain), with spectral attributes and ground-truth data and 2) a synthetic twin that uses latent features in the original datasets to reconstruct realistic spectral data (including sensor noise and processing artifacts) from the ground truth. The point cloud is dense and contains 3242964 labeled points. We used these datasets to explore the abilities of different deep learning approaches for automated geological mapping. By making Tinto publicly available, we hope to foster the development and adaptation of new deep learning tools for 3-D applications in Earth sciences. The dataset can be accessed through this link: https://doi.org/10.14278/rodare.2256

    Computer Vision-Based Hand Tracking and 3D Reconstruction as a Human-Computer Input Modality with Clinical Application

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    The recent pandemic has impeded patients with hand injuries from connecting in person with their therapists. To address this challenge and improve hand telerehabilitation, we propose two computer vision-based technologies, photogrammetry and augmented reality as alternative and affordable solutions for visualization and remote monitoring of hand trauma without costly equipment. In this thesis, we extend the application of 3D rendering and virtual reality-based user interface to hand therapy. We compare the performance of four popular photogrammetry software in reconstructing a 3D model of a synthetic human hand from videos captured through a smartphone. The visual quality, reconstruction time and geometric accuracy of output model meshes are compared. Reality Capture produces the best result, with output mesh having the least error of 1mm and a total reconstruction time of 15 minutes. We developed an augmented reality app using MediaPipe algorithms that extract hand key points, finger joint coordinates and angles in real-time from hand images or live stream media. We conducted a study to investigate its input variability and validity as a reliable tool for remote assessment of finger range of motion. The intraclass correlation coefficient between DIGITS and in-person measurement obtained is 0.767- 0.81 for finger extension and 0.958–0.857 for finger flexion. Finally, we develop and surveyed the usability of a mobile application that collects patient data medical history, self-reported pain levels and hand 3D models and transfer them to therapists. These technologies can improve hand telerehabilitation, aid clinicians in monitoring hand conditions remotely and make decisions on appropriate therapy, medication, and hand orthoses

    Archaeological palaeoenvironmental archives: challenges and potential

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    This Arts and Humanities Research Council (AHRC) sponsored collaborative doctoral project represents one of the most significant efforts to collate quantitative and qualitative data that can elucidate practices related to archaeological palaeoenvironmental archiving in England. The research has revealed that archived palaeoenvironmental remains are valuable resources for archaeological research and can clarify subjects that include the adoption and importation of exotic species, plant and insect invasion, human health and diet, and plant and animal husbandry practices. In addition to scientific research, archived palaeoenvironmental remains can provide evidence-based narratives of human resilience and climate change and offer evidence of the scientific process, making them ideal resources for public science engagement. These areas of potential have been realised at an imperative time; given that waterlogged palaeoenvironmental remains at significant sites such as Star Carr, Must Farm, and Flag Fen, archaeological deposits in towns and cities are at risk of decay due to climate change-related factors, and unsustainable agricultural practices. Innovative approaches to collecting and archiving palaeoenvironmental remains and maintaining existing archives will permit the creation of an accessible and thorough national resource that can service archaeologists and researchers in the related fields of biology and natural history. Furthermore, a concerted effort to recognise absences in archaeological archives, matched by an effort to supply these deficiencies, can produce a resource that can contribute to an enduring geographical and temporal record of England's biodiversity, which can be used in perpetuity in the face of diminishing archaeological and contemporary natural resources. To realise these opportunities, particular challenges must be overcome. The most prominent of these include inconsistent collection policies resulting from pressures associated with shortages in storage capacity and declining specialist knowledge in museums and repositories combined with variable curation practices. Many of these challenges can be resolved by developing a dedicated storage facility that can focus on the ongoing conservation and curation of palaeoenvironmental remains. Combined with an OASIS + module designed to handle and disseminate data pertaining to palaeoenvironmental archives, remains would be findable, accessible, and interoperable with biological archives and collections worldwide. Providing a national centre for curating palaeoenvironmental remains and a dedicated digital repository will require significant funding. Funding sources could be identified through collaboration with other disciplines. If sufficient funding cannot be identified, options that would require less financial investment, such as high-level archive audits and the production of guidance documents, will be able to assist all stakeholders with the improved curation, management, and promotion of the archived resource

    Studying the impact of agrivoltaic systems across the water-energy-food (WEF) nexus

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    L'umanità sta affrontando molteplici sfide dovute alla crisi climatica, all'aumento della domanda di cibo a causa della crescita della popolazione mondiale e alla conseguente richiesta di energia. I sistemi agrivoltaici (AV), la combinazione sinergica di impianti fotovoltaici e attività agricola, rappresentano una soluzione al dibattito energia-cibo. I sistemi AV prevedono l'installazione di impianti fotovoltaici su terreni agricoli, preservando il suolo agricolo per la produzione di cibo. L'obiettivo principale di questa tesi è stato quello di studiare la crescita delle colture nei sistemi AV, la loro risposta ecofisiologica, produttiva e la conversione energetica. Lo studio è stato effettuato attraverso prove in campo e modelli di simulazione con il fine di sostenere la sicurezza alimentare e promuovere l’agricoltura sostenibile in tutto il mondo rispettando i principi connessi al nesso acqua-energia-cibo. Nei capitoli di questa tesi è stato evidenziato come il sistema agrivoltaico è in grado ottimizzare la produzione di energia elettrica e di cibo, sono stati studiati i principali tratti eco-fisiologici che influenzano la crescita delle colture sotto sistema AV, sono stati utilizzati modelli di simulazione per prevedere l'energia convertita dai sistemi AV e la resa delle colture e l'impatto dell'albedo delle colture sulla conversione energetica di sistemi AV bifacciali.Humanity is currently facing multiple challenges due to the climate crisis, the increasing in food demand due to a global population growth and the consequently increasing demand for energy. Agrivoltaic (AV) systems, the synergistic combination of photovoltaic systems and conventional agricultural practices, represent a solution to the energy-food debate. AV systems includes installing large PV systems on agricultural land while preserving the agricultural soil for food production. The main objective of this thesis was to study the growth of crops under agrivoltaic system and their response in terms of productivity, morphology, physiology and on energy conversion throughout field activity and model simulations to support food security and sustainable agriculture worldwide across the water-energy-food nexus. On the chapters of this thesis was highlighted how agrivoltaic system can optimise electricity and food production, furthermore the main eco-physiological traits that influence the crop growth under AV system were studied and finally, were used simulation models to forecast energy and crop yield and the impact of the measured crop albedo from different crops on the energy conversion of two AV systems with bifacial PV modules

    Insights into temperature controls on rockfall occurrence and cliff erosion

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    A variety of environmental triggers have been associated with the occurrence of rockfalls however their role and relative significance remains poorly constrained. This is in part due to the lack of concurrent data on rockfall occurrence and cliff face conditions at temporal resolutions that mirror the variability of environmental conditions, and over durations for large enough numbers of rockfall events to be captured. The aim of this thesis is to fill this data gap, and then to specifically focus on the role of temperature in triggering rockfall that this data illuminates. To achieve this, a long-term multiannual 3D rockfall dataset and contemporaneous Infrared Thermography (IRT) monitoring of cliff surface temperatures has been generated. The approaches used in this thesis are undertaken at East Cliff, Whitby, which is a coastal cliff located in North Yorkshire, UK. The monitored section is ~ 200 m wide and ~65 m high, with a total cliff face area of ~9,592 m². A method for the automated quantification of rockfall volumes is used to explore data collected between 2017–2019 and 2021, with the resulting inventory including > 8,300 rockfalls from 2017–2019 and > 4,100 rockfalls in 2021, totalling > 12,400 number of rockfalls. The analysis of the inventory demonstrates that during dry conditions, increases in rockfall frequency are coincident with diurnal surface temperature fluctuations, notably at sunrise, noon and sunset in all seasons, leading to a marked diurnal pattern of rockfall. Statistically significant relationships are observed to link cliff temperature and rockfall, highlighting the response of rock slopes to absolute temperatures and changes in temperature. This research also shows that inclement weather constitutes the dominant control over the annual production of rockfalls but also quantifies the period when temperature controls are dominant. Temperature-controlled rockfall activity is shown to have an important erosional role, particularly in periods of iterative erosion dominated by small size rockfalls. As such, this thesis provides for the first high-resolution evidence of temperature controls on rockfall activity, cliff erosion and landform development
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