Search

This thesis investigates the dynamic behaviour of rocking steel frames that employ gap-opening mechanisms at the column-foundation and beam-column connections to avoid inelastic deformations under lateral loads. Current realizations of these structures incorporate supplementary energy-dissipation elements aimed at providing control against large demands. Therefore, they rely largely on yielding components that accumulate damage during strong dynamic action. Although the provision of yielding devices in rocking frames can improve their seismic performance in certain conditions, it obscures the understanding of their complex and unconventional nonlinear dynamics. Besides, sacrificial yielding components often result in systems with permanent post-earthquake deformations that require non-negligible labor in terms of replacement, re-centring and repair. To address these shortcomings, this thesis starts by investigating the complex non-linear dynamics of pure rocking frames and proposes a Finite Element modelling framework that accurately represents their behaviour over a wide range of excitation frequencies and amplitudes. The methodology, applied to multi-storey steel frames, captures the presence of sub-harmonic resonances and higher-modes. Additional demands due to the asymmetric member boundary conditions are identified in the rocking columns. The knowledge gained is then applied to develop a novel damage-avoidance solution that utilizes the controlled plastic buckling of tape-spring elements with curved cross-sections, often used as components of deployable spacecraft structures. Glass-Fibre Reinforced Polymer is selected as the material due to its high strength-to-weight ratio, elastic buckling properties, and geometric design flexibility. A numerical simulation protocol for the bracing members is developed and a comprehensive parametric study is presented. It is demonstrated that the system performs successfully under static and discrete sine-sweep loads for single-bay one and three-storey rocking frames. These concepts are extended to realistic multi-storey multi-bay rocking buildings. The performances of the proposed systems are compared to conventional steel moment frames. The buildings are subjected to a series of static load cycles, discrete sine-sweep ground motions, and earthquake records (using Incremental Dynamic Analysis). It is thereby demonstrated that Buckling-enabled Bracing enhances the static, non-linear dynamic, and seismic performance of rocking buildings by significantly reducing the member forces and response quantities. The fragility curves demonstrate that rocking frames equipped with BECB (or BEB) exhibit lower probabilities of exceedance for storey drifts and accelerations, than conventional moment frames. Subsequently, these findings are summarized and future research areas are discussed.

When subjected to lateral excitations, a variety of structures, such as museum artefacts, historical buildings, bridge piers and post-tensioned walled buildings, might uplift and set into rocking motion. Although this mechanism can efficiently limit the internal forces at their base, the possibility of overturning or experiencing increased lateral deformations and accelerations may severely affect the functionality of rocking structures. Nevertheless, suitable seismic control strategies are presently limited and consist mostly in preventing rocking motion altogether, which may induce undesirable stress concentrations and lead to impractical interventions. This thesis examines the alternative of using supplemental rotational inertia devices to control the seismic response of rocking structures. The newly proposed strategy employs inerters, which are mechanical devices that develop resisting forces proportional to the relative acceleration between their terminals and can be combined with a clutch to ensure they act only in opposition to the motion. The fundamental dynamic behaviour of the system is firstly examined considering a free-standing rigid block model. By deriving the corresponding equations of motion, it is demonstrated that the inclusion of the inerter effectively reduces the frequency parameter of the block, resulting in lower seismic demands and enhanced stability due to the well‐known size effects of the rocking behaviour. In subsequent chapters, this simplified single-degree-of-freedom model is gradually extended in order to incorporate the effects of post-tensioned tendons, structural flexibility and higher modes on the response. Overall, the analyses conducted under coherent pulses and real ground motion records show that inerter-equipped structures experience reduced seismic demands and lower probabilities of exceeding limit states usually associated with structural and non-structural damage. The fundamental knowledge acquired in the first part of this thesis is finally applied to control the seismic response of rocking timber buildings. To this end, a set of three post-tensioned rocking walled buildings, comprising 3, 6 and 9 storeys, is designed following direct-displacement-based design guidelines. Additionally, a set of clutched and non-clutched ball-screw and gear inerters is designed using a newly proposed pre-dimensioning procedure. The performance of bare and protected structures with different levels of apparent mass ratios is then compared in terms of peak inter-storey drifts and floor accelerations. Special attention is paid to the resisting forces developed in the inerters and the mechanism to transfer them to the structural diaphragm. Likewise, the ability of the inerters to control higher-mode effects is closely examined. Finally, a performance-based assessment with particular emphasis on non-structural and contents damage is conducted considering a database of 202 pulse-like ground motion records. Overall, the results of this assessments confirm the trends observed in the analytical examinations of the earlier chapters.

In the absence of signals from Global Navigation Satellite Systems (GNSS), Inertial Navigation Systems (INS) are usually used to position vehicles. However, INS sensors are commonly plagued by noises, which grow exponentially over time during the multiple integration computation, leading to a poor navigation result. More so, the error drift is characterised by a time dependent pattern. This thesis proposes several efficient deep learning - based solutions to learn the position and orientation error drifts of the vehicle using Recurrent Neural Networks, such as the simple Recurrent Neural Network (sRNN), Long Short-Term Memory (LSTM), Gated Recurrent Unit (GRU) and the Input Delay Neural Network (IDNN). The thesis also investigates the use of the wheel encoder as an alternative to the accelerometer of the INS for vehicular positioning, and for the first time explores the potential of deep learning using the simple recurrent neural network to learn the uncertainty present in the wheel encoder's output. These uncertainties could be manifested as wheel slips because of wet/muddy road drive or worn out tyres; or changes in the tyre size or pressure. The proposed solution has less integration steps in its computation, and as such, has the potential to provide a more accurate estimation of the vehicles position. In contrast to previous papers published in literature, which focused on travel routes that do not consider complex driving scenarios, this thesis investigates the performance of the proposed deep learning-based models to accurately estimate the position of the vehicle in challenging scenarios. These scenarios include, roundabouts, hard brake, sharp cornering, quick changes in vehicular acceleration, successive left and right turns. The performance of the deep learning models are then further evaluated extensively on longer-term GNSS outages of 30s, 60s, 120s and 180s duration respectively, over a total distance of 493 km. The experimental results obtained show that the proposed deep learning model using wheel odometry data is able to accurately position the vehicle with up to 93% reduction in the positioning error of its original (physics model) counterpart after any 180s of travel.

Astronomical space missions require stable and fast target pointing to achieve their science objectives. To obtain high pointing stability, a Fine Guidance System (FGS) mechanism is normally used to provide fine pointing control. In this project, we analyse possible implementations of an FGS that uses piezoelectric actuators. This would not only allow for stable pointing but also allow for fast and reliable FGS operation. An optical setup was designed and built to test the proposed mechanism. Using a PID control loop, stability of up to 0.2 pixels on the focal plane was achieved. Considerable drifts that were observed without the FGS mechanism were eliminated using this control loop. The mechanical and thermal characteristics of the piezoelectric FGS mechanism were studied using finite element analysis to better characterise and optimise it. A software simulator was also produced to allow us to study the performance of centroid determination and the effects of an FGS mechanism in various situations. We conclude that a reliable and fast operating FGS can be implemented using piezoelectric actuators, allowing future astronomy missions to reach a stability of 5-10 milliarcseconds at a correction rate of up to a few hundred hertz. This stability, together with other advantages such as the mechanical simplicity of the system would make it ideal for space satellites such as the Twinkle satellite. It would also be an ideal system for many other low Earth orbit satellites, where many orbital disturbances need to be managed.

New types of position sensitive thermal neutron detectors for use in neutron imaging are in high demand due to the rising cost of 3He used in most existing thermal neutron counters. A novel 6Li doped scintillation glass sheet (GS20) coupled to a multi-anode photomultiplier tube with a portable data acquisition system, known as the Solid State Neutron Detector (SoNDe), is one possible solution. This study focuses on the characterisation and understanding of the Solid State Neutron Detector for application at the European Spallation Source (ESS), where the Small Angle Neutron Scattering instrument requires approximately 400 of these modular detectors. Therefore, understanding the efficiency, crosstalk, gain non-uniformities, and response to radiation of the SoNDe module is crucial. Radiation from a number of sources were used to establish the main characteristics of the detector and the results compared. Sources included a 404 nm laser, 241Am producing alpha particles, AmBe producing fast and moderated neutrons as well as gamma-rays, 60Co and 137Cs producing gamma-rays, and a pelletron accelerator producing protons. A simulation written using the Geant4 toolkit, verified through comparison to measured data, was used to study the details of the detector construction and to predict the response of the detector to possible sources of background radiation at ESS. The gains and gain stability of the photomultiplier pixels are important for operation at ESS. The relative pixel gains of the photomultiplier tube were provided by Hamamatsu for each individual photomultiplier. However, given the importance of these numbers to determining detector response and setting readout thresholds, they were also measured using various methods. These methods included the use of a collimated alpha source and a laser spot centred on each pixel separately, a uniform square diffuse laser beam simultaneously illuminating all pixels, and a moderated neutron source illuminating all pixels. The alpha, neutron, and diffuse laser results are similar to the Hamamatsu measurement and give potential methods of detector calibration. The laser spot data shows a slightly different gain, and is less directly comparable to the production measurement. The gain stability of the detector system and its drift characteristics were measured using the collimated laser and alpha-particle sources. The 404 nm laser was close in wavelength to the peak in the scintillation emission spectrum of the GS20 glass. Drifts of 10−4 %/hr were found. This indicated a minute shift in gain in the detector over an extended period of time (34 - 67 hours). The stability studies also highlighted the importance of a sufficient warm-up period, 1 hour in duration, prior to operation. Various sources were scanned across the detector face to provide an in-depth look at the position dependence of the pulse-height response of the detector. Fine scans over the entire detector area were performed with a collimated laser beam at single and 60 photoelectron light intensity levels. The results revealed areas of higher/lower response (dead spaces) some of which is due to the presence of photomultiplier tube structures, such as focusing electrodes between the cathode and first dynode. The crosstalk between pixels was measured using both the collimated alpha source and the laser. The percentage of signal in the neighbouring pixels surrounding the target pixel was measured. A range of 0.0 - 3.0 % was measured for the laser data, and 2.5 - 9.8 % for the alpha data. Both data sets were greater than the Hamamatsu results of 0.0 - 2.1 %. While the laser light was highly directional the scintillation light was emitted isotropically and gave rise to the increased crosstalk percentages in the surrounding pixels. The spreading of scintillation light from its point of origin was investigated in more detail with the Geant4 simulation. Cross-pixel scans in the horizontal, vertical, and diagonal directions were carried out with collimated alpha particle and proton beam sources. The alpha beam spot on target was ∼ 1 mm diameter, while the proton beam spot was ∼ 0.1 mm diameter permitting finer scanning steps. The measured results revealed the variation in signal amplitude as the source was scanned across the detector face with the proton data presenting an especially stringent test for the predictions of the Geant4 based model of the detector. The Solid State Neutron Detector's ability to successfully detect thermal neutrons is highly important. A moderated AmBe source was used to irradiate the detector. A clear neutron peak was distinguished. A Geant4 simulation was used to compare with the measured data, and simulate possible neutron/gamma backgrounds with energies ranging from 0.025 eV - 100.0 MeV. The Solid State Neutron Detector has been thoroughly characterised in stability, relative gain, and response to various forms of radiation. The detector optimisation revealed a number of possible alternative se tups, with the originally proposed setup proving the most effective.

Gyrotaxis describes the tendency of bottom-heavy motile micro-organisms to swim sideways under the balancing of gravitational and viscous torque. A suspension of gyrotactic microswimmers will self-focus into a plume in a pipe with a shearing downflow. This work utilises the dilute assumption and model microswimmers, such as the gyrotactic Chlamydomonas and Dunaliella, as hydrodynamically contributing (but not interacting) particles in a flowing suspension that are also subjected to rotational noise. In this framework, the suspension is governed by the Smoluchowski equation and the Navier-Stokes equation. We then further reduce the Smoluchowski equation into a transport equation for the swimmers using the Fokker-Planck model and the generalised Taylor dispersion (GTD) model. Both models are used to calculate the formation of the gyrotactic plume and the subsequent blip instability via a stability analysis. The Fokker-Planck model is found to be not as accurate as the GTD model. The calculation of the gyrotactic plume also results in the discovery of a series of imperfect transcritical bifurcations in the uniform solution and a singular solution when the Richardson number approaches a certain threshold. The transcritical bifurcations are likely linked to the formation of bioconvective patterns, whereas the singular solution is found to be an extension of Kessler (!986). Despite encouraging results from the GTD model, it cannot be applied in a general flow field or capture shear trapping in inhomogeneous shear flows. Therefore, a new model using a novel transformation and local approximation of the Smoluchowski equation is proposed. The resulting new transport model performs better than the GTD model due to its ability to capture shear trapping. It also exposes many new drifts and dispersions arising from the interaction between the orientational and spatial dynamics. Nevertheless, this new framework can be further improved by including the semi-dilute effect and better modelling at the wall.

The continuous increase of carbon dioxide (CO2) level, nowadays, has become a knotty problem and life-threatening which is envisaged as the next pandemic. The question is: Can we use it as a plentiful feedstock instead of leaving it as a waste gas? The answer is Yes. Recently, more and more scientists and researchers put their efforts into this topic, converting CO2 into a valuable source of chemicals and fuels. Within current technologies, reverse water-gas shift (RWGS) reaction has attracted wide attention because the produced carbon monoxide (CO) is the versatile compound within the field of C1 chemistry, having the potential to be applied in large-scale when coupled to downstream processes (e.g. Fischer-Tropsch and methanol synthesis). However, due to its endothermic nature, RWGS requires high temperatures and it has kinetic limitations in terms of CO2 conversion at lower temperature regions. Besides, methane (CH4) production from the competitive methanation process is produced at low and moderate temperatures. Therefore, further efforts must be put into the development of active catalysts to overcome the slow kinetics and improve the production distribution towards carbon monoxide. In this present research work, firstly, a comprehensive literature review was done in order to guide the catalyst selection. Following this, Ni, Fe, and Cu oxides have been chosen as active metals, supported on the homemade CeO2-Al2O3 mixed oxide matrix for catalysts synthesis. Catalysts were tested in fixed-bed continuous flow reactors and multiple characterisation techniques were applied. Results indicate that Ni-based catalysts present outstanding CO2 activation, but they also favour CH4 formation and thermal sintering. Effects of selected promoters FeOX and CrOX were studied. Results show that FeOX promoted Ni/CeO2-Al2O3 has better activity/stability balance under critical reaction conditions due to Ni-Fe interaction, as well as the textural property/thermal stability supplied by FeOX. As for Fe-based catalysts, they show less activity, especially at lower temperatures. But their catalytic performance can be largely improved by adding CuOX and NiOX as promoters. Among promoted catalyst systems, Fe-Cu/CeO2-Al2O3 catalyst reveals a considerable CO2 conversion at 500oC for about 40% with nearly 100% CO selectivity. Then, we focused on the study of Fe/Cu oxides ratio effects, developing a bimetallic Fe-Cu catalytic system. Results indicate that when the CuOX increases to 75% (based on the total amount of active metals), 0.25Fe0.75Cu shows the best CO selectivity. And the electronic interaction between Fe and Cu has proven to be important for CO2 activation and H2 dissociation. Besides, the Cu species are found to be partially incorporated into CeOX lattice, which is the key to produce CO. Based on these findings, a new series of FeOX promoted Cu/CeO2-Al2O3 (Fe2O3:CuO = 0.25:0.75) was developed. Catalysts were calcined at three different temperatures (400oC, 600oC, and 800oC) and tested in direct CO2 hydrogenation to methanol. To unravel the reaction pathway of this reaction over our prepared catalysts, advanced technique in-situ Diffusive Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS) was applied. CO and formate species were detected simultaneously, evidencing the co-existence of the redox pathway, the RWGS + CO-hydro pathway, and the formate pathway during the reaction. In any case, the calcination temperature has a great impact on the product distribution. Besides, the final experimental chapter suggests a Cu-Fe/CeO2-Al2O3 catalyst calcined at 600oC, which shows the highest CO2 conversion and considerable methanol selectivity due to highly dispersed CuOX and FeOX particles, and the existence of CuCeOX structure. Overall, this thesis is based on rational design and reactive studies to produce highly effective catalysts for CO2 conversion via RWGS. It is hoped that this work will inspire more investigation in this field.

In recent years, anaerobic digestion of biomass and food wastes/residues to produce biogas has become one of the most attractive routes for producing renewable energy. Biogas mainly consists of methane (CH4, 40-75 vol.%) and carbon dioxide (CO2, ca. 25-60 vol.%). To enable the maximum utilisation of biogas, CO2 removal is necessary. Therefore, this project developed a novel integrated membrane-catalytic process for biogas upgrading, which consists of a membrane separation technology (to capture the CO2 from biogas) coupled with non-thermal plasma (NTP) activated catalysis (to convert the captured CO2 into CH4), enabling methane enrichment. The development of the individual processes was undertaken first. Specifically, a new method was developed to modify SAPO-34 zeolite membrane (using nanoporous organosilica) to heal of the membrane defects, and the developed membrane unit showed an improved CO2/CH4 selectivity (from ca. 60 to 160) without compromising the CO2 permeance. Then, the development of highly efficient catalysts (based on zeolites and MOFs) for the NTP-catalysis system was performed for CO2 hydrogenation. For example, under NTP at 6 kV, the Ni (15 wt.%) supported on UiO-66 MOF catalyst showed a good CO2 conversion (ca. 80%) and CH4 selectivity (ca. 99%). In addition, in situ techniques, such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterisation, and kinetic studies were carried out to investigate the mechanism of the NTP-catalysis based on the CO2 hydrogenation reaction. At the laboratory scale, the integration of membrane separation with NTP-catalysis was successfully achieved to realise the CH4 enrichment of synthetic biogas. The integrated system showed satisfactory carbon capture efficiency (CCE) and carbon utilisation efficiency (CUE) of ca. 91.8% and 71.7%, respectively, as well as the good stability (40 h).

Autonomous mobile platforms are going to be huge part of the future transportation and autonomous navigation is the critical part of autonomous platforms. An autonomous mobile platform navigates the vehicle by perceiving the environment through the sensors mount on the vehicle, and acting on the data it receives from these sensors by making sense of the environmental and surroundings. As a result, an autonomous mobile platform consists of localisation aka positioning and path planning. Both of them require very accurate sensor measurements. In terms of accuracy, sensor can generally be divided into two groups (a) High accuracy sensors like the state-of-the-art in LiDAR and vision sensors e.g. mobile-eye sensor. (b) Low accuracy sensors whereas GPS (accurate within 2-10 metres) sensor and IMU (suffering from drifts) could be fused to improve the other method of positioning. These are expensive process due to offline map creation. To deal with low accuracy sensors, researchers normally use very complex models, which again run into performance reliability and consistency issue. Furthermore, it is common believe, that when navigating autonomously, perception and situation cognisance is an important component to navigate safely and there have been a huge research on AI enabled perception such as Mobile Eye and Tesla car which uses 2D cameras for its perception. In this research, an innovative method is proposed to use rich vision sensor holoscopic 3D camera for environment perception with artificial intelligent algorithms to observe road objects and learn their 3D behavioural for reliable detection and recognition. The sensor provides rich information - 3D cubic visual information about the environment including the very valuable "depth information" to imitate third coordinate of real world. To learn the objects, different AI algorithms are studied and in particular deep learning model is proposed that provides a reasonable good result. To evaluate the innovative holoscopic 3D sensor, we applied to face recognition challenge under different face expression where 2D images are considered to fail. However the holoscopic 3D sensor outperform and delivered outstanding performance by recognising faces under different expression by only training on the neutral face using a simple AI algorithm. Then we design and develop holoscopic perception database of 200000 frames for autonomous car. The experimental result has shown a promising result that AI algorithm, particularly deep learning algorithm learns effectively from holoscopic 3D content compared to traditional 2D images even those DL models which were designed for visual features yet holoscopic 3D images contain motion data which shall be exploited.

Metal-organic frameworks (MOFs), also called porous coordination polymers (PCPs), have recently gained tremendous attention in catalysis due to their high surface areas and structural diversity and tunability. However, their relatively low thermal stability, compared to zeolites and metal oxides, hinders their practical application in high-temperature gas-phase reactions. UiO MOFs (UiO for Universitetet i Oslo), are known as one of the most thermally and chemically stable MOFs studied in recent years. In this PhD research, the suitability of UiO MOFs-based catalysts in the catalytic reactions is systematically evaluated. UiO MOFs were synthesised by the microwave-assisted method. The resulting materials were carefully characterised and compared to those synthesised solvothermally. The results proved that the microwave-assisted method can be a suitable alternative to the traditional solvothermal method. In order to identify the real role of MOFs as catalyst supports in the catalytic reactions, a comparative study of Pt NPs supported on UiO-67 and ZrO2 using operando near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) was performed, in which CO oxidation was used as the probe reaction. Pt NPs, loaded on UiO MOF by linker design (LD) and wetness impregnation (WI) methods, showed a higher activity than those loaded on the commercial ZrO2 support due to their improved NPs size and dispersion. Plasma-assisted catalytic dry reforming of methane (DRM) using PtNP@UiO-67 catalysts was also evaluated, enabling the catalytic application of UiO MOFs under plasma as an alternative to thermal catalytic DRM. In situ diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS) was also carried out to monitor the surface reactions on PtNP@UiO-67 catalysts in the plasma-assisted catalytic DRM. The findings of this study indicated the potential of using UiO MOFs to develop new catalysts in the future.

Research into the seismic performance of structures with oil dampers have so far been driven primarily by the structural engineering community, with influential experimental work on the topic originating mainly from large scale shaking table testing of fixed-base prototype frames. Despite considerable advancements over the years in building complexity and realism into these test structures, little to no experimental effort has been made to investigate dynamic soil-structure interaction in such structures. Fixed-base shaking table testing of structures fitted with oil dampers confines energy dissipation to the supplemental damping devices alone, neglecting any contributions from foundation-soil inertial interaction that may arise in the field. A considerable portion of literature on oil dampers in structures emanates from a mathematical optimisation background, proposing computational algorithms to solve for optimal damper sizes and locations in a structure. Such iterative linear analysis is conducted in the frequency domain, and offers limited physical insight into the different facets of this complex nonlinear Soil-Structure Interaction (SSI) problem. Numerical and analytical work examining the effects of SSI on buildings with oil dampers have been limited in nature, often resorting to equivalent linear procedures to simplify the modelling of geometric and soil nonlinearities at the foundation-soil interface. This research seeks to address some of these limitations by pioneering the application of high gravity geotechnical centrifuge testing as a viable research tool to experimentally investigate dynamic SSI in buildings with oil dampers. Miniature oil dampers for use in small-scale model structures were developed for this purpose, following a series of trial-and-error experimentations. Sixteen centrifuge tests were conducted in total, each involving two similar 2-DOF linear elastic structures, one fitted with miniature oil dampers, and one left bare for comparison. Ground flexibility was varied between tests by changing frame base fixity conditions from fully rigid fixed base, to shallow embedment of raft foundations into dry dense and loose sand beds. Aspect ratios and foundation bearing pressures of the model structures were also varied to trigger different levels of SSI. Miniature accelerometers were used during the centrifuge tests to measure soil and structural accelerations, along with miniature load cells to track experimental oil damper hysteresis during shaking. The model frames were subjected to near resonant frequency sinusoidal excitations of different magnitudes to trigger different levels of SSI. The dynamic response of the structures to realistic multi-frequency component excitations was also recorded. Inter-storey oil dampers as tested in this study have delivered consistent improvements to the seismic response of structures for all of the input motions and ground conditions investigated in the centrifuge. It was found that additional viscous damping in the superstructure came at the expense of inertial interaction at its foundation-soil interface. The damped soil-structure systems were less sensitive to changes in ground conditions and foundation bearing pressures compared to their regular bare frame counterparts. Optimal oil damper control over structural accelerations and drifts was recorded for fixed base conditions, during weak excitations that did not trigger considerable resonance in the superstructures. Upon shallow embedment of the rafts into dry sand beds, reductions in damper control were reported, reaching minimal levels for the loose sand cases during moderate to strong near resonant frequency excitations. These reductions were not the result of subpar performance of the damped structures per se, but rather a consequence of the considerable improvement in the dynamic response of the regular frames being used as comparative benchmarks. If the foundation of a regular structure is permitted to rock during strong shaking, experimental evidence points to dynamic responses that are close to those expected from a similar structure fitted with oil dampers. However, such natural seismic mitigation measure was shown to be highly variable and unreliable for weaker excitations. Base flexibility and dynamic SSI did not have adverse consequences on the performance of structures fitted with oil dampers. While it is true that reductions in oil damper hysteresis were observed with reducing base fixity, this should not be interpreted as degradation in damper effectiveness. On the contrary, when excited close to resonance, the damped frames exhibited similar, albeit slightly lower, floor accelerations as base fixity was reduced. Estimation of the seismic input energy into a soil-structure system during near resonant frequency shaking showed both, damped and bare structures benefiting from natural rocking isolation; releasing the foundation rotational kinematic restraints lowers total energy going into the superstructures, causing the oil dampers in the frames to do less work. Even during SSI, the oil dampers continued to be the primary source of energy dissipation in the soil-structure systems. Lastly, the promising application of using nonlinear lumped-parameter structural models, with hyperbolic foundation moment-rotation backbone curves to predict centrifuge data, was demonstrated for the damped and regular bare structures. Such simplified models, solved in the time domain, offer a more elegant solution during early stage design compared to the response spectrum procedures currently advocated by published guidelines on the analysis of damped structures.

The earliest evidence for the presence of people on Sahul, present-day Australasia, represents some of the earliest conclusive evidence for early seafaring worldwide. As seafaring requires forward planning and a detailed understanding of the maritime environment, the migration to Sahul gives important insights into human behaviour, technology, and skills in the deep past. But despite its significance, the timing and nature of the migration process are debated. Open ocean and coastal tidal currents are likely to have had a strong effect on early seafaring. In order to better understand this process, it is crucial that ocean dynamics and their effects on maritime movement are examined. In this study, dynamic effects of the maritime environment on seafaring are explored with high-resolution computer models of open ocean and coastal tidal circulation. A particle-tracking algorithm is used to calculate large ensembles of simulated ocean drifts in an Ocean General Circulation Model. These are analysed to determine probable timescales and trajectories of movement between Sunda (Southeast Asia) and Sahul. In addition, changes in tidal currents at lower mean sea levels are investigated and the effects of tidal dynamics on early seafaring are explored, using a barotropic hydrodynamic model of the Australian coast. A discussion of the combined effects of open ocean currents, coastal tidal currents, and winds on voyages between Sunda and Sahul reveals that these processes had a strong but variable influence of on human movement. Familiarity with currents and winds would have been advantageous to early seafarers. By using oceanographic research methods to explore an archaeological issue, new perspectives are gained on current debates surrounding early seafaring.

In this work I report on a hybrid trap platform for sensitive optomechanics experiments with applications in quantum physics, thermodynamics and material science. We characterise a miniature linear Paul trap which can be used in combination with an optical cavity. The low-frequency harmonic motion of a nanoparticle levitated in a Paul trap can be detected with competitive sensitivities using a super-resolution imaging technique. This same method can be applied to characterise trap stability and nanosphere parameters such as mass with a 3% uncertainty. Using this same method at room temperature and at pressure of 3×10−7 mbar, we were able to measure an ultra-narrow mechanical linewidth of ∼80 μHz with a novel phase sensitive scheme which removes slow drifts in the mechanical frequency. We used this measurement to place new bounds on dissipative versions of wavefunction collapse models. Using two optical cavity modes with different frequencies interacting with a nanoparticle levitated within a Paul trap realises a versatile optomechanical system, which can be operated in regimes dominated by either linear or quadratic optomechanical coupling. We demonstrated cooling of the centre-of-mass motion of the nano-oscillator exclusively provided by the quadratic coupling. This nonlinear interaction gives rise to a highly non-thermal state of motion which matches well with theoretical predictions. In the linear regime, we report cooling down to Teff=21±4 mK limited by Paul trap noise, demonstrating stable trapping in the cavity standing-wave down to pressures ∼10−6 mbar. Using the same technique, we show that in theory, near ground state cooling could be achieved with better electronics used in conjunction with the filtering cavity developed as part of this work.

Oil shales are widely defined as fine-grained sedimentary rocks containing a considerable amount of organic matters, known as kerogen. Through retorting, oil shale could be thermally converted to shale oil, which makes utilisation a possibility. The shale oil production is largely governed by the kerogen content, as well as the interactions between kerogen and mineral matrix. To clarify these phenomena, the AGR experiments were carried out using six Chinese oil shales from different regions distributed in Northeast China, namely Fushun (FS), Xingsheng (XS), Xinghua (XH), Laoheishan (LHS), Jinzhou (JZ) and Wulin (WL) oil shale. Compared with coal or biomass, these samples are predominantly comprised of quartz and clays, which together make up to approximately 50-80 wt%. Economically, it requires more energy to process oil shale during aboveground retorting (AGR), hence less profit. From an environmental viewpoint, a sufficient amount of solid wastes containing organic residues would induce unique challenges in disposal. To maximise the use of oil shales, this project aims to (1) characterise physicochemical properties of oil shale; (2) develop advanced thermal conversion technologies; (3) explore the potential of co-gasification with coal and (4) synthesise value-added nanoparticles from oil shale wastes. Oil shale shows a poor grindability owing to the nature of oil shale being a sedimentary rock. Given its high grinding resistance, reducing the size of oil shale particles requires excessive energy. The conventional heating and microwave-enhanced pre-treatment of oil shale was conducted to enhance oil shale grindability. The samples were milled and sieved into a uniform size fraction of 1-1.18 mm, whilst a separate set of samples were cut into cube-shaped specimens. The prepared samples were pre-treated and crushed to study the failure mechanisms, as well as changes in uniaxial peak strength and specific breakage rate in comparison to that of untreated samples. Results show that the strength of FS oil shale was significantly reduced by 62.5% whilst the specific breakage rate increased by 42% after a short exposure to 1 kW microwave irradiation. The improvement was approximately 50% higher than that observed after conventional heating. Hence, results suggest that microwave processing could lead to a more significant and rapid improvement in milling compared to conventional pre-heating, and without adversely affecting fuel quality. Subsequently, the thermal behaviour and kinetic triplets of oil shales (and their respective blends) were studied using a thermogravimetric analyser via a model-free method, whilst the product distribution and oil composition were analysed by Fischer assay test and gas chromatography-mass spectrometry, respectively. The results have shown that the activation energy generally exhibited a decreasing trend with increasing WL fraction due to the catalytic effects of minerals and positive, non-catalytic effects of hydrogen-rich organic constituents on cracking and ring-open reactions. The coupling effect could also increase the gas yield by restricting the coke formation. Moreover, shale oil was redirected towards lighter oil with limited oxygenated compounds. However, extensive dehydrogenation and aromatisation reactions would inversely enhance the coke formation, in particular at low H/C ratio. Hence, upon optimum blending ratio, co-pyrolysis of different oil shales has the potential to lower energy barrier and improve oil quality without the expense of catalysts. Additionally, oil shale, which has high SiO2 and Al2O3 content, is a potential refractory agent due to its high melting point. Herein, the ash fusion characteristics of different oil shales together with the commonly used Qinghai bituminous coal (QH), and their respective blends were investigated under a CO/CO2 atmosphere. The automated image-based ash fusion test was used to monitor and quantify the complete melting behaviour of ash samples from room temperature to 1520 oC. The transformation of mineral matters was characterized experimentally via X-ray diffraction and verified via thermodynamic modelling in FactSage software. Results showed that the excessive melting point (EMP) of QH coal ash is the lowest but would increase with oil shale addition. This is due to the formation of anorthite which restricts the formation of gehlenite and subsequently low-melting hercynite. However, the sintering point of QH coal ash decreased with the addition of oil shale due to the formation of low-melting aluminosilicate. Hence, blending coal with oil shale can modify the melting behaviour by complementing ash chemistry to meet the requirements of a gasifier, but without adversely affecting thermal performance. The amorphous SiO2 in oil shale ash can be effectively extracted as an inorganic silica precursor. Herein, mesostructured siliceous form materials (SFM) were synthesised from oil shale ash via a green and time-saving microemulsion templating method and modified with polyethyleneimine (PEI) for carbon capture. The effects of preparation conditions on sample morphology and pore structure were studied to understand the characteristics of inorganic silica precursors. Results show that the SFMs possess 3-dimensional porous framework with a large surface area of 901.3 m3/g and a pore volume of 2.0 cm3/g. The CO2 adsorption performance of PEI-impregnated SFMs was investigated in terms of CO2 adsorption capacity and cycling stability under a simulated flue gas condition. The results show that pore-expanded SFMs with 50 wt% PEI loading exhibited higher CO2 uptake (109 mg/g-adsorbent) compared to the baseline materials (50 mg/g-adsorbent) and no appreciable reduction in CO2 uptake was observed in the first 12 cycles. The DRIFTS spectra of CO2-evacuated adsorbents illustrated the presence of alkylammonium carbamates residuals and newly formed urea species, illustrating degradation mechanisms. To summarise, this project has demonstrated that (1) microwave-enhanced pre-treatment could reduce energy consumption of comminution due to a significant improvement on oil shale grindability; (2) co-pyrolysis of oil shales from different regions could promote the conversion owing to the positive synergistic interactions; (3) the high-melting oil shale could act as refractory agent to alleviate ash-related problems during co-gasification; (4) with a simple and green synthesis route, the “dirty” oil shale waste could be converted to value-added material, which is a promising candidate for carbon capture. The findings of this work could provide useful information for the development of AGR technologies, especially whilst using low-grade oil shale. The proposed synthesis method is a potential strategy in managing solid waste and reducing the carbon footprint of oil shale industries.

The study to be presented here examines the practical processes and outcomes of commercial arbitration in China. It aims to provide an anthropological account that illustrates and explains how a transnational legal institution such as commercial arbitration is implemented in the contexts of Chinese arbitral organs and local bureaucratic sectors. Specifically, this thesis takes on two tasks. The first is to identify and present some of the Chinese arbitral practices that can be described as “vernacularized” due to their deviance from the “best practices” of international arbitration law. In particular, I am concerned with practices that pertain to aspects of institution-building and dispute-processing. The second is to analyze what may be the “local factors” – in both institutional and sociocultural terms – that contribute to these practical results of vernacularization. Drawing on my twelve-months ethnographic fieldwork in China, I show that opposed to the Euro-American model that it borrows, Chinese commercial arbitration has become highly bureaucratized and mediatory. I argue that these drifts towards state bureaucracy and mediation can be explained by a distinct mode of “reasoning” in which the aspiration to state authority operates as a presumptive constraint on how local actors consider their compliance or other forms of engagement with legal rules. For participants observed, this constraint is not necessarily absolute, but it does have a presumptively decisive force that tends to undermine other competing reasons for engaging with law. By foregrounding the deliberative aspect of transnational legal practices in their local settings, what I attempt to achieve is to better identify and explain its relationship with the broader “sociocultural” conditions with which local actors are entangled. In so doing, it is my hope that this study would not only help better explain China’s frequent deviance from its commitment to the rule of law but also break fresh ground in studying legal phenomena anthropologically in the Chinese society and beyond.

In recent years, events of intermittent low- and high-drag have been observed in turbulent channel flows near transition. During the low-drag events, the wall shear stress, on average, temporarily reduces to about 40% below its time-averaged value and the velocity profile approaches Virk's maximum drag reduction (MDR) asymptote. There are still open questions regarding this phenomenon, for example the characteristics of Reynolds shear stress (RSS) during the events and whether they continue to exist at higher Reynolds numbers (i.e. in the so-called ``fully-turbulent" flow regime). Investigating intermittencies in turbulent flow close to transition requires knowledge of intermittencies during the laminar-turbulent transition process. However, there is currently no time-resolved experimental wall shear stress data available in the transitional flow regime for channel flow. To study the laminar-turbulent intermittency, instantaneous wall shear stress (using hot-film anemometry, HFA) is probed at the transitional Reynolds numbers. Higher order statistics show that with increasing Reynolds numbers (from the laminar flow regime), the laminar-turbulent intermittency firstly grows, then diminishes, and eventually disappears by Reτ ≈ 72, where Reτ =uτ h/ν and uτ, h and ν indicate the friction velocity, channel half-height and kinematic viscosity, respectively. Using multiple hot-film probes, information about the large-scale turbulent structures during transition is inferred. Additionally, a flow visualization has been conducted to observe the large-scale structures, which qualitatively supports the wall shear stress results. Beyond transition, simultaneous measurements of wall shear stress and velocity (using laser Doppler velocimetry, LDV) have been conducted to detect and characterize the low- and high-drag intermittencies for Reτ = 70 - 250. The fraction of time spent in these intermittent events is observed to be independent of Reynolds number when the criteria for minimum time duration is kept constant in ``inner" units. The previously observed spike in the ensemble-averaged wall shear stress before and after the low-drag events is found to be an artefact of the conditional sampling and ensemble-averaging process and is not a physical phenomenon. Conditionally-averaged streamwise velocity profiles get closer to Virk's MDR asymptote, near the wall, for all the Reynolds numbers studied. Simultaneous wall shear stress and RSS measurements are carried out for Reτ = 70 and 85. An increase in the conditionally-averaged RSS is observed during the low-drag events for all the wall-normal locations measured, but is particularly apparent for y+ ≈ 20 - 40, where y+ = y uτ/ ν and y is the wall-normal distance. When using HFA for long-time wall shear stress measurements, minimizing the non-thermal calibration drift is a significant challenge. A new method to minimize recalibration in thermal anemometry using a non-linear regression technique is proposed and investigated. This new method was utilized in the current work and finds potential applications in cases of correcting for non-thermal calibration drifts in long time measurements and also in scenarios where the direct calibration of hot-films is not possible or suffers significant uncertainties.

This thesis mainly study the application of the Gaussian Processes (GPs), especially the application of GPs regression for multiple-person tracking. Furthermore, we explore the scalability of the GPs model. Most existing multiple-person tracking algorithms are still limited by abrupt human pose change, scale change and lighting condition tend to drifts. We introduce a GPs regression based observation model to deal with these challenges. During the tracking process, background information is taken into account to cope with the dynamic background, the GPs regression based observation model fuses prior information to make a tracking decision, which can cope with short term occlusion. Another benefit is that the information of the target in the current frame can be extracted to re-weight the target information in the previous frame, after that a tracking decision is made, this can be seen as a transfer learning strategy. Recently, neural networks have made breakthroughs in various fields. Especially convolutional neural networks (CNNs) have made significant progress in image processing area. The key to the success of CNNs in image processing is that it has a high model complexity and can process high-dimensional features layer-by-layer. After that, extracting different levels of abstract information for further use. We explore the scalability of GPs model, by stacking multiple GPs together, we can construct a deep architecture with building blocks of GPs. This deep hierarchy Gaussian process model is capable of processing high-dimensional input and extracts different levels of abstract information, which is suitable for image processing. We further explore the GPs model equipped with the convolutional kernel, making it benefit from the non-local generalization of convolutional structure and achieving better performance for image data.

Increasing awareness of personal health conditions has emerged as a key driver in point-of-care breath analysis for early diagnosis. This also demands real-time monitoring of air pollution based on internet of things (IoT) networks. Both systems rely on the development of scalable mobile-embeddable devices. Conventional devices face challenges like high power consumption, severe baseline drifts, and cross-analyte interferences, compromising the detection accuracies. Recently, 2D nanomaterials and their functionalization with metal oxides (MOx) have become attractive for high performing sensors. Solution processing of these materials coupled with inkjet printing can be promising for fabricating low-cost devices. I have addressed the abovementioned challenges from the perspectives of materials, device fabrication, and algorithmic approaches. I develop an inkjet-printed array of graphene-ZnO and graphene-WO₃ system integrated onto miniaturized CMOS platforms to detect NH₃ and acetone for potential diagnosis of diseases. I also develop a machine-intelligent classification system based on inkjet-integrated α-Fe₂O₃-rGO CMOS devices to selectively measure NO₂ air pollutants. The ink formulation and the theoretical model I develop facilitate uniform printed morphology, achieving excellent device reproducibility. Coupled with temperature modulation (TM) algorithms I develop, the devices achieve high responsivity, eliminated baseline drift, reduced response/recovery time, high SNR, and extraordinary repeatability. Moreover, a sensor array is established for compensation of cross-analyte interference. The influences of interferents are addressed by machine learning (ML) approaches. The predictive system quantifies NO₂ concentrations under different humidity conditions, with excellent separation between classes. Furthermore, the fully inkjet-printed room temperature NO₂ sensors assembled within the developed multi-sensory hub have performed reliable measurements in a real-world environment. My strategy to combine the sensing material, inkjet printing onto the CMOS platform, and TM/ML algorithms promises a robust system that outperforms conventional devices. The versatile technologies enable reliable multi-material array for potential multi-disease diagnostics. The systems developed also pave the way for ubiquitous implementation of adaptive wireless-connected monitoring systems.

Many managers ask them self “Why our transformational efforts fail? Why? We did everything in a full harmony with the best business practice learnt in business schools and collected during our experience.” However, the fact is that the transformation of troubled companies as the Bulgarian State Railways is a very demanding process hindered by many internal and external factors. Theories of organizational adaptation as well as Organizational Ecology discuss the challenges from the right perspective: They consider organizational inertia and process of spontaneous institutionalisation major obstacles any reorganization necessitated by environmental drifts has to deal with. The power of the factors undermining the reorganisations is so strong that in most cases the management will probably fail. The research looks at the major factors that affect the fitness of the corporation and describes the attempts of the managers to recover the going concern status of the enterprise. The study investigates the Hypotheses that the adaptive capacity and the speed of reorganisation of the troubled BSRG decline with: (1) the length of service of the inertial management, (2) the strength of the limits imposed on the company performance by the institutionalised collective labour agreements, (3) the strength of its organisational opacity and asperity, and (4) the intensity of the conflicting institutional demands presented by the internal and the external audience. The real problem is that the transformation of BSRG from a company on the verge of bankruptcy to a financially sustainable company took long eight years and the cost of the reorganization turned to be enormously high. However, while confirming to certain extent the validity of the Theory of population Ecology, the dissertation simultaneously presents managerial approaches that increase the likelihood of organisational survival by improving the adaptive capacity of the enterprise.

Harnessing quantum mechanics to solve problems intractable on classical computers is one of the foremost goals of applied physics. Trapped ions make an excellent physical platform for such a quantum computer, as they have demonstrated unparalleled qubit operation fidelities and memory times, but significant challenges remain in scaling up these systems. A promising scalable architecture is a photonically connected network of mixed element trapped ion nodes, each containing a few ions of two species. Poor quality remote entanglement links between nodes can be tolerated, if entanglement between ions in the same node can be achieved with high fidelity. While local gates have been repeatedly demonstrated between ions of the same species, the fidelity of mixed element quantum gates have not previously surpassed the fault tolerant threshold, above which errors can in principle be corrected. In this thesis we demonstrate an entangling operation between ⁴³Ca⁺, useful for its long lived qubits, and ⁸⁸Sr⁺, well suited for remote entanglement, using a novel mechanism requiring only one laser to manipulate both species. This relatively simple scheme, which is independent of either qubit frequency, allows us to achieve Bell state fidelities of F = 99.8(1)%. We assess the operation of the gate further with state and process tomography, which achieve Bell state fidelity F = 98.1% and average gate fidelity F̅ = 99.05(6)% respectively, though they are hampered by experimental drifts during the long data collection. Finally, we use interleaved randomised benchmarking to get the best estimate of our gate errors, finding an average gate fidelity of F̅ = 99.62(3)% for a sequence of 60 interleaved gates. Along with a demonstration of entanglement between two ⁸⁸Sr⁺ ions, achieved with fidelity F = 95.9(4)%, this work paves the way towards demonstrating an elementary mixed species quantum network in future experiments.

Although Deep Neural Networks (DNNs) are widely used in applications such as facial or iris recognition and language translation, there is growing concern about their feasibility in safety-critical or security-critical contexts. Researchers have found that DNNs can be manipulated by poison attacks like backdoor attacks, and are vulnerable to evasion attacks like adversarial attacks. Attackers can compromise DNN models by injecting backdoors during the training phase or by adding imperceptible perturbations to model inputs via adversarial attacks. To ensure secure and reliable deep learning systems, it is crucial to identify and mitigate these vulnerabilities. Despite active efforts within the adversarial machine learning community to identify vulnerabilities in deep neural networks (DNNs), there remains a significant gap between current research and the practical deployment of these systems in the real world. According to recent studies, model practitioners often do not anticipate potential attacks on their models in the near future. This is largely due to the fact that previous research on machine learning security has oversimplified threat models, which do not accurately reflect real-world scenarios. In this dissertation, I seek to reveal and mitigate DNN vulnerabilities in practical settings by designing and measuring attacks and defenses against DNNs under realistic threat models. Particularly, my dissertation consists of three components that target different practical constraints. The first two components focus on uncovering and mitigating DNN backdoor attacks under practical constraints, one during the attack injection phase and one after the attack injection. As training a production model from scratch is resource-intensive, entities often train their models through transfer learning, which breaks existing backdoors. I propose a more advanced backdoor attack called latent backdoor that can survive transfer learning. Next, although existing work assumes models are static and the injected backdoors stay in place permanently, production models are usually periodically updated to address data distribution drifts. I conduct a comprehensive study to understand how backdoor attacks behave on these time-varying models and propose a smart training strategy that can reduce backdoor survivability significantly with negligible overhead. The last component focuses on defending black-box adversarial attacks in real-world deep learning models. To resolve the challenge that today's production models receive millions of queries per day, I design and implement a scalable and robust defense system against black-box adversarial attacks on DNNs. Finally, I summarize my work on revealing and mitigating real-world DNN attacks under practical constraints and discuss my insights in this area. I aspire my work can bridge the gap between the exploration of DNN attacks and defenses and their application in real-world systems. Additionally, I hope my work can inspire further research on DNN vulnerabilities under real-world scenarios.

Prognostics and health management (PHM), which aims to convert preventive maintenance (periodical maintenance) into predictive maintenance (condition-based maintenance), has gained increasing attention in the current era of the Internet of Things (IoT), Industry 4.0, and Industrial AI. A significant amount of research has been conducted using a variety of signal processing, statistical analysis, and machine learning algorithms to develop different PHM systems. Feature learning is a crucial task in bridging the gap between data and models. Time-series data in sensor environments exhibit continuous changes and drifts, which require PHM models to balance static and time-independent uncertainty for feature learning. In this dissertation, a novel deep autoencoder with time-lagged regularization is proposed. This method can learn features from the time-domain and frequency-domain and detect underlying weak-sense stationarity. A change point detection strategy is developed by combining the time-lagged autoencoder with a dissimilarity-based anomaly detector. The effectiveness of the proposed change point detection algorithm is validated using public benchmarking datasets, fault detection and prognostics of ion milling etching machine data, non-artificial segments recognition, and long-term assessment of intracranial pressure signals. The proposed methodology is compared with state-of-the-art benchmark approaches and found to establish an improved PHM model with sustainable performance in discovering change point features in time-series signals.

In the last decades, there have been great efforts to bring robotic teams to the necessary autonomy level that is required for the safe and efficient exploration of unknown environments. Particularly, long-term, large-scale, or time-critical missions can profit from deploying multiple self-sustaining robotic systems due to their improved accuracy and robustness. The typical paradigm for deploying multiple robots in these cases is that each robot maps and operates in a distinct region of the environment and then collaborates by sharing the gathered information with the other robots. Accordingly, the collective knowledge of all robots allows collaborative teams to foster a more accurate joint estimation which can significantly contribute to the success of a mission. These aspects are essential for rescue robotics in disaster response since multiple robots can explore the environment faster and, when equipped with complementary sensing modalities, can increase the chances of successfully locating human survivors or identifying hazardous areas. However, many of these environments are unstructured and degraded, thus imposing significant challenges on a robot’s perception and locomotion systems. Robotic teams can mitigate these challenges by utilizing various sensor cues, such as visual, thermal, and depth, and by employing different robotic systems, such as ground and aerial robots. Although many perception systems are already designed to rely on several input modalities, the support of various heterogeneous sensors with different characteristics and parameters is often impaired. Consequently, heterogeneous sensor systems might inflict substantial limitations on the system’s capabilities that can inhibit the overall performance of the robots. Nevertheless, a perception system’s ability to generalize well to different sensors ensures long-term applicability with less fine-tuning, which is highly relevant to search and rescue applications. Therefore, resilient mapping and localization systems require a refined orchestration of the input modalities to be robust and suitable for the multitude of robot and sensor deployment scenarios. In this doctoral thesis, we investigated the use of compact spectral representations to analyze the characteristic properties of measurements and trajectory estimations. In particular, we identified several crucial aspects and open problems of collaborative multi-robot mapping and localization where spectral approaches yield useful insights. Assuming an existing centralized multi-robot framework for communication and joint optimization, we initially deal with the multi-modal global localization task to reduce estimation errors by recognizing already visited places at the centralized server. Since the measurement representation and sensor fusion strategy constitutes a significant aspect for achieving good accuracy and precision, we propose a robust localization pipeline that exploits the spectral domain along with a novel spherical representation to circumvent issues associated with noise and drifts. In the second part, we broadcast the optimized multi-robot map to the individual robots to reduce the onboard estimation errors. We can efficiently identify discrepancies between the onboard and the server estimates by analyzing their spectral properties. The novelty of this approach lies within the spectral analysis that enables our system to compensate for the type of onboard failure by classifying the structural disparities. We show that our approach can even overcome estimation failures and degeneracies in the onboard estimation by exploiting the combined knowledge from the robotic team. In the final part of this thesis, we explore localization and mapping approaches with active consideration of semantic information in the environment. We infer an accurate semantic segmentation of surroundings by virtue of a spherical spectral analysis. Utilizing the resulting semantic segmentations to build a constellation of semantic objects provides a more unique representation of a scene than only a description using appearance or geometric primitives. Therefore, we further investigate the use of semantic objects apparent in structured urban environments to improve the detection of already visited places by conservatively filtering the mapped locations. In summary, this thesis advances the research in robust global localization, collaborative multi-robot mapping, and semantic scene understanding by means of spectral analysis in the Euclidean, graph, and spherical domains. We demonstrate the effectiveness of our systems in multiple experiments within complex underground scenarios but also in structured urban scenarios. Finally, the problems addressed in the context of the thesis can also readily help to solve many of the typical robot localization and mapping problems in various other environments.

The body of this paper is a formatted version of text which exists natively on the web and is accessible at www.personalequation.art. Its non-linear narrative is meant to accompany and mirror, not describe, the artwork in the exhibition. The following two paragraphs are copied from the exhibition statement accompanying Personal Equation, which is on view in the Reading Room at the Fayetteville Public Library from April 3 to June 30, 2023: A personal equation is one that attempts to account for the inevitable role of subjectivity in scientific observations. The term was coined by astronomers in the 18th century who, upon noticing inexplicable differences between their measurements, realized that the accuracy of an observation is influenced as much by the observer as it is by the instrument being used. In 1877, for example, Giovanni Schiaparelli noticed dark lines on the surface of Mars that he believed to be channels of water criss-crossing its arid surface, causing a frenzy of speculation about the potential for life on the distant world. Only decades later, after many failed attempts to reproduce the finding, was it realized that Schiaparelli had probably seen the shadows of the blood vessels in his own eye. With these drawings I explore and embrace my own personal equation, grappling with the hyper-specificity of looking out into the cosmos as a human being trapped on the surface of the Earth. Through quiet scale-shifts and implied comparisons, drawings of widely disparate subjects are interwoven in an alchemic dance of familiarity and ambiguity. References for these drawings are pulled thoughtfully from thoughtless drifts through astronomical archives, photographs of my everyday life, and the depths of the internet where, just as in science, many contradicting realities are forced to co-exist. Like Schiaparelli, I’m trying desperately to find meaning in the noise with imperfect instruments and narrowly limited senses.

The human eyes are always moving. Even during periods of fixation when visual information is acquired, a persistent jittering of the eyes (ocular drift) is occasionally interrupted by small rapid gaze shifts (microsaccades). Though much has been learned in the last 20 years about the perceptual roles of fixational eye movements, little is known about the consequences of their active control for fine pattern vision and depth perception. Using custom techniques for high-resolution eye-tracking and precise control of retinal stimulation, this dissertation describes three studies that investigated the consequences of controlled fixational eye movements for visual perception of fine patterns in two and three dimensions. The first study addresses whether fixational eye movements are controlled to meet the needs of a demanding visual task and their contributions to visual acuity. We show that in a standard acuity test, humans actively tune their drifts to enhance relevant spatial information and control their microsaccades to precisely place stimuli within the foveola. Together these eye movements contribute 0.15 logMAR to visual acuity, approximately two lines of an eye chart. The second study addresses the perceptual and computational impact of tuning ocular drift. We show that humans are sensitive to changes in visual flow generated by drifts of different sizes. Changes in sensitivity are fully predicted by changes in effective power of luminance modulations delivered by drift, suggesting that drift acts as a mechanism for controlling the effective contrast of the retinal stimulus. The third study addresses the impact of binocular fixational eye movements on fine depth perception. We show that these movements, specifically the opposing movements of the eyes (vergence), are beneficial for stereovision. In the absence of disparity modulations from fixational vergence, fine depth perception is significantly impaired. The research described in this dissertation advances the field in several fundamental ways by showing that (a) contrary to traditional assumptions, ocular drift is tuned to the demands of the visual task; (b) the precise spatiotemporal structure of the luminance changes from ocular drift predictably impacts visual sensitivity; and (c) stereoscopic vision is a dynamic process that uses temporal disparity modulations generated by fixational vergence.

Large disturbances in the solar wind, such as Coronal Mass Ejections, can trigger the most significant geomagnetic activities near the Earth, i.e., storms. In the ionosphere, various electron density structures can form during storms, which are usually accompanied by abrupt electron density gradients that can significantly impact the propagation of radio signals going through or reflected by the ionosphere. The spatial scales of these storm-time electron density structures span from thousands of km to several km or less. Formation and dynamic evolution of these ionospheric density structures are manifests of the complex Magnetosphere-Ionosphere-Thermosphere (MIT) coupling processes during storms. Using a combination of multi-instrument observations and numerical simulations, we performed a comprehensive study investigating various aspects of these dynamics and their drivers. The findings of this study contribute to our systematic understanding of the storm-time MIT coupling processes and could assist future missions targeting these density structures. In this research, we studied the formation processes of two density structures that often occur at mid and high latitudes during storms: Storm Enhanced Density (SEDs) and polar cap patches. SEDs are electron density enhancements at mid-latitudes and are often suggested as the main plasma sources for the patches in the polar cap region when they extend to high latitudes. Several mechanisms have been proposed in the past to explain the segmentation of SEDs into patches. Using state-of-the-art simulation tools, we proposed a new segmentation mechanism associated with boundary flows between the Region-1 and Region-2 Field Aligned Currents (FACs) when the partial ring current drifts towards the dayside. No sudden external interplanetary magnetic field variations or transient reconnection are required in this mechanism. Besides the boundary flows, other fast convection flow structures and their temporal variations, such as SAPS, have also been suggested to be important for ionosphere density structuring processes. Using a comprehensive ground- and space-based instrument suite, we performed a detailed analysis of the formation and temporal evolution of SubAuroral Polarization Streams (SAPS) during a moderate storm. We found that the SAPS electric field formed before a substorm onset, and was accompanied by a local magnetic field dip and a dispersionless ion injection from the flank side. In the conjugate ionosphere, the SAPS developed near the equatorward boundary of the Harang reversal. The observed complex signatures in the coupled magnetosphere and ionosphere can be explained by a two-loop current wedge generated by the enhanced plasma pressure gradient and the diamagnetic effect of the structured ring current following the particle injection. One recently discovered aspect of the storm-time ionospheric responses is the hemispheric asymmetry. We performed a detailed case study of the drivers of the hemispheric asymmetry in electron density observed during the storm recovery phase. The asymmetries were observed simultaneously in the dawn and afternoon sectors and had opposite polarities. They were suggested to be driven by a combination of the hemispheric asymmetries in the thermospheric composition, vertical drifts, and Travelling Ionospheric Disturbance (TID) activity.

With the embrace of the performance-based seismic design as the state-of-the-art design method, recent emphasis has been placed on eliminating its drawbacks and facilitating its application in practice. This study aims to propose an alternative design method: performance-based analytics-driven seismic design, which is applied to steel moment resisting frame buildings. First, the seismic performance of self-centering (with post-tensioned connections) and conventional moment resisting frames (with reduced-beam section connection) is comparatively assessed. The comparison indicates that the economic benefit for adopting the post-tensioned connection is not significant. Then, an end-to-end computational platform, which automates the seismic design, nonlinear structural model construction, and response simulation (static and dynamic) of steel moment resisting frames is developed. Using this platform, a comprehensive database is developed, which includes 621 special steel moment resisting frames designed in accordance with modern codes and standards and their corresponding nonlinear structural models and seismic responses (i.e., peak story drifts, peak floor accelerations, and residual story drifts). Using this database, the efficacy of mechanics-based, data-driven, and hybrid (combination of mechanics-based and data driven) approaches to estimating the seismic drift demand are evaluated. The evaluation results reveal that the hybrid approach has the best performance whereas the mechanics-based model has the lowest performance. Next, a set of non-parametric and parametric surrogate models are developed for estimating the engineering demand parameter distributions. A comparative assessment of the proposed surrogate models and the simplified analysis method proposed by FEMA P-58 is conducted to demonstrate the superior predictive performance of the former. Finally, the effect of various design variables on the collapse performance of steel moment resisting frames are evaluated. The research findings presented in this study helps to facilitate the application of 2nd performance-based earthquake engineering framework in practice and thus better help to create earthquake-resilient communities.

Urban, or anthropogenic, soils are those which are highly influenced by human activity. These soils are spatially complex due to the physical disturbances to which they are subjected through direct anthropogenic impacts. Human intervention and their impacts on urban soils are the predominant cause of the unique characteristics of urban soils, which are not present in natural, undisturbed environments. Changes in landscape vegetative cover from natural to urban environments could have a negative effect on biodiversity by loss of habitat, the capacity of soil to store C, and reduction of biomass.To better classify, characterize, map and determine carbon fractions of urban soils this research’s main objectives were to: (1) find relatively undisturbed soils in the urban study area to use as a reference for future studies and use USDA soil taxonomic methods to characterize and classify these urban soils; (2) determine if mid-DRIFTS can serve as a rapid method for calcite and dolomite assessment in urban soils when compared to the volumetric calcimeter method, and if acid pre-treatment effectively removes calcite and dolomite from urban soil samples; (3) compare four methods to determine organic carbon in highly disturbed environments and compare methods to determine organic carbon in soil with inorganic carbon present and (4) develop a classification of urban soils based on taxonomic distance, create a map of The Ohio State University soils, and develop a measure of soil disturbance by comparing the urban soil classification to an anthroposequence. In Chapter 2, historical Ohio State University campus maps were used to locate and sample areas where minimally disturbed soils might be found. These pedons, inadvertently presented different stages of an anthroposequence. Pedon 1 showed a mostly homogeneous parent material. Pedon 2 had large concentrations of inorganic C derived from the calcareous glacial outwash parent material. Foreign materials and disrupted horizonation in Pedon 3 were evidence of significant disturbance. Information obtained from soil characterization in urban environments provides information for policymakers to understand the urbanization of soil environments and to enhance ecosystem services. Soil characteristics found on these three sites established a baseline for Chapter 5.In Chapter 3, specific mid-infrared frequencies (mid-DRIFTS) known to be associated with carbonates, dolomite, and calcite were identified, and specific peak areas were measured and trained with results obtained with the volumetric calcimeter method. Multiple linear regression was used to estimate total carbonates with peaks areas at 2980 cm-1, 2515 cm-1 and 730 cm-1 resulting in a root mean squared error (RMSE) of 3.56%. Greater prediction accuracy of calcite (875 cm-1) and dolomite (2515 cm-1) were achieved using single peaks in bivariate relationships resulting in RMSE of 3.09% and 2.30%, respectively. Soil samples were treated with 1 M HCl for 24 hours to remove carbonates, and total carbonate, dolomite, and calcite contents were estimated again using both volumetric calcimeter and mid-DRIFTS. The reduction in carbonate concentrations post-acid treatment was considerable (97% for dolomite, and 96% for calcite and total carbonates), but it was not complete; thus, this could compromise estimation of other soil carbon fractions such as total soil organic carbon concentrations. In Chapter 4, organic carbon was assessed using multiple methods in alkaline and non-alkaline soil samples. The dry combustion, loss-on-ignition at 400° and 550°, and dichromate digestion methods with the non-alkaline dataset were all strongly correlated (r > 0.82). However, paired t-tests revealed significantly different results between all four methods (p < 0.05). For the alkaline data set the two loss-on-ignition methods and the dichromate method were strongly correlated with each other (r = 0.91), however the two dry combustion methods were weakly correlated with the others (0.45 ≥ r ≤ 0.67). The dichromate oxidation proved to have the lowest variance of the 5 methods tested (0.25% OC). In Chapter 5, the OSACA (Outil Statistique d'Aide a la Cartogenese Automatique) algorithm was used to determine and cluster taxonomic similarity distances between the properties of observed soil properties in 108 soil profiles across the campus. Seven clusters were determined to be the optimum number for this area. Once these soil classes were modeled and predicted across the study area, it was found that random forest prediction techniques performed better than geostatistical methods such as regression-kriging. This work demonstrates that the contiguous classification system is a feasible option to use in the classification of anthropogenic soils, and the comparison of samples sites to known pedons and classes.

Abstract: Multi-Tiered Concentrically Braced Frames (MT-CBFs) represent a bracing configuration where two or more concentric braced panels are stacked between the storey levels in multi-storey buildings or between the ground and roof levels in single-storey buildings such as sports facilities, airplane hangers, or industrial buildings. This configuration is commonly used in tall storeys when it is impractical or uneconomical to employ one braced panel along the frame height. The multi-tiered configuration is preferable to avoid the use of large brace sections and impractical brace connections in design. A large proportion of MT-CBFs in Canada is located in low-to-moderate seismicity regions where low-ductile frames, such as Limited Ductility (Type LD) or Conventional Construction (Type CC) category, are often preferred to avoid relatively complicated seismic design and detailing requirements. Limited research studies have focused on the seismic stability and design of such low-ductile MT-CBFs. The current special seismic design provisions for Type LD MT-CBFs in the current Canadian steel design standard (CSA S16), which often requires performing multiple tedious analyses, particularly for tall frames, lack sufficient background research. For Type CC MT-CBFs, the Canadian steel design standard does not provide specific seismic design requirements. This research aims to investigate the seismic behaviour of Type LD and Type CC steel MT-CBFs with the focus on the stability of their columns, assess the current seismic design provisions, and propose enhanced and yet simplified design guidelines for the design of such frames in low-to-moderate seismicity regions. An industrial building located in Montreal, QC, Canada representing a moderate seismicity region, was selected. A parametric study matrix consisting of 64 low-ductile steel MT-CBFs was developed by varying various parameters, including the frame ductility level, frame height, tier height ratio, brace and column cross-sections. The selected frames were then designed to CSA S16-14 provisions, excluding the key design requirements for MT-CBF columns of Type LD and Type CC. The nonlinear numerical models of the frames were then developed using fibre-based elements in OpenSees, including the connection effects. The models were then used to perform nonlinear response history analyses under 30 ground motion records. Results of the NLRH analyses showed multiple column buckling cases in both Type LD and Type CC frames. It was confirmed that the inelastic response in the selected frames was limited. No tension yielding has occurred in the tension-acting braces of the majority of the selected frames. Although the majority of compression-acting braces knuckled in compression, none of them entered the post-buckling zone. Storey drifts in all frames were significantly lower than the 2015 NBCC limit. Similarly, tier drifts were found to be noticeably lesser than the drift that can cause low-cycle fatigue fracture in braces. For Type LD frames, the axial compression forces did not exceed the design forces obtained using the capacity design principle. Additionally, in-plane and out-of-plane moments induced in the columns of Type LD frames were found to be lower than 6% and 8% of the respective column plastic moments in the plane and out of the plane of the frame. The columns of Type CC MT-CBFs experienced larger compression forces than their design forces. Column in-plane and out-of-plane moments observed in the columns of Type CC frames were lower than 8% and 28% of the respective column plastic moments in the plane and out of the plane of the frame. Improved and simplified seismic analysis and design methods were proposed for the design of Type LD and Type CC MT-CBFs with the emphasis on their columns. The adequacy of the proposed methods was examined for six case study frames, which confirmed that the proposed methods lead to a satisfactory seismic performance without column instability. The column size remained unchanged in Type LD frames and reduced in Type CC frames when compared to the columns designed to CSA S16-14.

The demand for energy is projected to increase by 50% within the next 20 years. Currently 80% of the world’s energy is supplied by non-renewable fossil fuels. Due to the increasing effect of the greenhouse gases, carbon tax, which is a form of taxation levied on the fixed carbon content of the fuels is becoming a reality. These factors bring the need for renewable energy carriers with minimal carbon footprint. Hydrogen is a promising candidate for a viable and clean energy carrier with its high gravimetric energy density and as a potential for fuel cell applications. Fuel cells would increase energy efficiency by bypassing the thermodynamical constraints of the internal combustion engine. Moreover, refineries use considerable amounts of hydrogen for internal treatment which is supplied by steam methane reforming. Steam reforming of a bio-renewable source such as ethanol or acetaldehyde would allow for a closed carbon loop due to the sequestration of the carbon dioxide during plant growth via photosynthesis.Traditional steam reforming catalysts are generally expensive due to their use of noble metals such as Rh. As opposed to the noble metals, cobalt is more economically feasible and ceria supported cobalt-based catalysts are promising candidates for steam reforming reactions. Previous work done in the Ozkan research group with Co/CeO2 catalysts has investigated effects such as surface-oxygen mobility, nature of the cobalt precursor and increasing the intimate contact between the support and the active metal. However, the nature of the active sites for the steam reforming reaction is still a topic of debate.In this study the cobalt and ceria active sites were investigated under actual steam reforming conditions. These in-situ studies along with more conventional characterization methods enabled us to shed light into the active sites of the steam reforming reaction, namely Co2+, Co0, Ce3+ and Ce4+. In the first chapter the background and literature survey on the subject is summarized followed by an overview of the reaction system. Chapter three focuses on comparing the effect of pretreatment of the catalysts and shows metallic Co sites to be more active. Moreover, Co sites were found to reduce under steam reforming conditions. After this milestone is established, chapter four delves into the effect of support morphologies and investigates the effect of different crystal planes on steam reforming which ultimately ties in with the reducibility of the cobalt species. Chapter five introduces the effect of particle size and shows how the surface chemistry is affected by synthesizing nano-scale particles. According to the results acquired in this research, oxidized Co surfaces were found to catalyze ethanol dehydration reaction which produces acetaldehyde. An alternative pathway for acidic surfaces was found to produce ethylene via ethanol dehydration reaction, whereas, easily reducible surfaces were found to be more active for hydrogen production. Tailoring the catalyst surface and controlling the extent of reduction were found to be essential in determining steam reforming activity.

Numerous researchers have investigated thinking that drifts away from what the individual was doing, thinking that is known as mind wandering. Their inquiries were often conducted in university lab settings with student participants. To learn about mind wandering in the daily life of working adults, this experience sampling study investigated intentional and unintentional mind wandering episodes as reported by working adults, ages 25–50, living across the United States. In this age frame, work and family responsibilities have increased in complexity and overlap. Using a smartphone app, participants were randomly notified to answer experience sampling surveys six times a day for up to five days. Eight questions concerned frequency, intentionality, and the descriptive characteristics of thought type, thought content, temporality, context, context demand, and emotion. Based upon 7,947 notification responses and 4,294 reported mind wandering episodes, the research findings showed that mind wandering is a common thinking experience in working adult daily life and is differentiated by intentionality, parent status, and gender. Parents reported more frequent mind wandering and intentional mind wandering episodes than nonparents. Episode thought type was most often indicated as practical thought. Episodes were more often reported as having the content related to context although out of context mind wandering episodes were also highly reported. Context demand and emotion at the time of the notification were related to mind wandering episode frequency and were further differentiated by intentionality, parent status, and gender. Working parents reported mind wandering episodes during higher demand, particularly male parents, than nonparents. By generating new knowledge about the thinking life of working adults, this study’s results and methodology contribute to the fields of leadership and change, thought research, intrapersonal and interpersonal psychology, work and family studies, and education. Future studies focused on underlying factors related to the mind wandering of working adults and the differences between parent and nonparent mind wandering may inform our understanding of working adult mind wandering. This dissertation is available in open access at AURA, https://aura.antioch.edu/, and OhioLINK ETD Center, https://etd.ohiolink.edu.

The ever-increasing demand from scientific and oceanographic communities for conducting research activities in remote deep oceans has led to the development of long-range Autonomous Underwater Vehicles (AUVs). These platforms open up a world of new AUV applications, including persistent monitoring and data-collection in some of the most inaccessible areas on Earth. The extreme range of these vehicles could facilitate the completion of currently impossible tasks. However, deploying AUVs for long periods of time comes with its own challenges. Even though considerable effort has been directed towards developing navigation techniques for AUVs, a self-contained low-power solution yet remains a challenge for missions of the order of months, rather than days or hours. In answer to the presently limited navigation capability, this work develops a TerrainAided Navigation (TAN) technique which, relying on a small number of low-power sensors, is able to prolong underwater missions without the need for external support or regular surfacing. Bathymetric observations are collected using low-informative sonars. State estimation is performed by utilising the Rao-Blackwellized Particle Filter (RBPF). To make the navigation algorithm computationally feasible for low-power processing boards with limited computational resources, the filter estimates the 2-D position of the vehicle and the 2-D speed of the water-currents near the vehicle. The performance of the proposed navigation solution is evaluated using unique field data that was collected during three multi-day AUV deployments of up to approximately 200 km range and depths greater than 3000 m in the Southern Ocean. To assess whether TAN can cope with coarse bathymetric maps typically available for remote deep oceans, the original ship-constructed 50 m resolution map is degraded through a sub-sampling process and three additional maps of 100 m, 200 m and 400 m resolution are generated. Provided techniques to escape from local minima, the algorithm demonstrates sufficient robustness to face challenging conditions, such as strong water currents, motion along a low-informative terrain, or even the absence of bathymetric information for prolonged time periods. The use of Dead-Reckoning (DR) navigation resulted in an error of over 40 km after only a three-day long mission, whereas TAN appears to be able to place a bound on the localisation error growth. Depending on the resolution of the employed map, TAN accuracy varies from a few meters to 1.5 kilometres on average. To extend further the navigation challenge, the TAN algorithm is evaluated during an aspirational example of a science-driven mission for continuous mid-water column survey from Svalbard (Norway) to Barrow (Alaska) under the Arctic sea-ice, a range in excess of 3200 km. The inability to surface in conjunction with the degraded performance of heading sensors and the drift caused by water-currents make the overall navigation problem extremely challenging. A simulated environment is developed incorporating heading error models, both for a magnetic compass or a gyrocompass, and water-currents derived from models of the water circulation in the Arctic Ocean. The performance of the TAN algorithm is examined with respect to the employed heading sensor and a range of vertical distortions applied to the Arctic terrain map. In this case, DR navigation inevitably drifts from hundreds to thousands of kilometres, whereas the simulation results show that TAN can provide acceptable localisation accuracy given a moderate distortion applied to the terrain model. By degrading further the terrain model, simulations show that TAN can fail when the vehicle crosses large areas of the map subject to interpolations. To reduce the risk associated with the filter divergence, it is demonstrated that the TAN performance can massively be improved by using a Rapidly-exploring Random Tree Star (RRT∗) algorithm to optimise a priori the path of the vehicle such that the AUV avoids crossing highly uncertain regions of the Arctic terrain map. Simulation results show no filter divergence when utilising the optimised path, despite the use of a heavily distorted bathymetric map and an echo-sounder with a pinging period of 60 seconds.

This study utilises an extensive set of sediment cores collected from a largely unstudied contourite and turbidite depositional system located on the Uruguay continental margin to identify a method of distinguishing deposits in the deep sea that are sourced from either gravity or bottom current sedimentary processes. The cores acquired by BG Group in 2014 targeted areas of the ocean floor that encompass both Late Pleistocene to Holocene age) large sediment drifts and large downslope canyons, where turbidite and contourite deposition occurs simultaneously. Core, sediment and micropalaeontological analysis has been used to answer three basic questions 1) Do the sediments collected from different geomorphic settings owe their origin to along-slope (contourite) or gravitational (turbidite) transport? 2) Do the drift sediments contain a record of palaeoceanographic change? and 3) Can micropalaeontologcial analysis resolve long-standing problems with differentiating along- and down-slope processes in the geological record. The presented study provides new data resolving these three questions for the upper, middle and lower Uruguayan slope. The new data comprises; 1. A detailed examination of the sedimentary facies of the (LatePleistocene to Holocene) Uruguay slope, while ground-truthing interpretations from seismic and bathymetric data collected from the same area that is broadly contemporaneous 2. A reconstruction of watermass migration using stable isotope, elemental ratios and foraminiferal indices accumulated on the Uruguay slope since the Last Glacial Maximum 3. A classification of foraminiferal assemblages for that are likely to be indicative of specific sedimentary facies in turbidite and contourite deposits in order to distinguish these facies from one another in a sedimentary environment where both contourite and turbidite deposition has occurred. This data elucidates some important new insights into the studied system and more broadly contourite and turbidite deposits globally: 1. A new model of mixed sedimentary system evolution on the Uruguay slope since the Last Glacial Maximum and how it is intrinsically linked to bottom-current/seafloor interactions 2. A new model for the flux of Antarctic sourced watermasses into the Atlantic basin across deglaciation 3. A new criterion for distinguishing contourites and from turbidite facies by using benthic foraminiferal ecological disturbance-succession patterns.

This thesis presents three different strands of research into fixational eye movements: the detection of microsaccades, the interaction between fixational eye movements and the visual stimulus, and the interplay of microsaccades and drift. Fixational eye movements actively sample the visual stimulus, generating spatial and temporal information about its structure while also preventing fading of the percept. Two new microsaccade detection methods are presented: the binocular correlation method most suited to data from video-based eye trackers and the monocular microsaccade detection method suited to microsaccade detection from high resolution adaptive optics eye tracking. These methods are systematically compared to the established standard method in the field by (Engbert & Kliegl, 2003) using the F1 score of the precision-recall metric. Manually labelled eye movement data will be made available online to be used as training and testing data for future microsaccade detection methods. The active responses of fixational eye movements to visual stimuli of different eccentricities, grating orientations, and levels of blur were also investigated. It was found that fixational eye movements exhibit systematic changes in response to stimulus eccentricity and orientation, but not to the different levels of blur tested. To explore possible underlying mechanisms data are presented on correlations of unreferenced motion thresholds and centre estimations with measures of fixational stability. Both were good predictors of fixational stability, suggesting that these or mutual underlying processes contribute to fixational eye movement control. Microsaccades and drifts are compared for their relative contribution to fixational stability. Traditionally microsaccades were considered to be correcting for the random error introduced by drift, but the data examined in this thesis suggest a complimentary role between microsaccades and drift in stabilising gaze.

This work aimed to produce using different and new microwave and ultrasound protocols monometallic metal nanoparticles of gold, palladium, silver, iridium and copper (Au, Pd, Ag, Ir and Cu) and bimetallic alloys of AuPd. The developed batch and continuous flow protocols originated from batch optimisation work mainly carried out with microwave synthesis of Au nanoparticles and were based on the sol-immobilization method with the production of stabilized colloids in water, organic solvents or a mixture of both, with PVA and PVP being used as stabilizers and ethylene glycol as the main organic solvent. The produced metal nanoparticles will be used for improving and developing current catalytic applications and eventually will be hugely beneficial for society. To tackle this multidisciplinary project the following targets have been chosen: To develop new metal nanoparticles synthesis protocols characterised by reduced synthesis time, improved production, minimal operation cost, minimal use of toxic reagents and controlled size and shape and to utilise the synthesised materials to convert fossil and bio-renewable feedstock via sustainable catalytic processes. This thesis could be divided into four areas: The first (chapter 3) focused on microwave synthesis of monometallic metal nanoparticles of Au, Pd, Ag, Ir and Cu and bimetallic metal nanoparticles of the alloy type of AuPd at different molar ratios (7:1, 3:1, 1:1, 1:3, 1:7). This included work carried out under batch and continuous flow regime; The second (chapter 4) focused on ultrasound synthesis of monometallic metal nanoparticles of Au, Pd and bimetallic metal nanoparticles of the alloy type of AuPd at a molar ratio of 1:1. All work was carried out under batch regime; The third (chapter 5) saw the application of several characterisation techniques (TEM, SEM/EDX, XPS and DRIFTS) to selected metal nanoparticles produced by microwave and ultrasound synthesis and supported on TiO2, C and CeO2. This provided important information regarding particles average size, shape, loading, composition, stabilizer traces and oxidation state; The fourth (chapter 6) focused on catalytic testing of some of the supported metal nanoparticles by using them as heterogeneous catalysts in liquid/gas phase reactions. In total seven reactions were tested, namely 4-nitrophenol reduction, carbon monoxide oxidation, propane total oxidation, furfural hydrogenation, cinnamaldehyde hydrogenation, formic acid decomposition and hydrazine decomposition; Even though some future work is mentioned in chapter 7, the main conclusion is that the new non-conventional synthesis protocols developed for this work have already allowed to address challenging issues in the areas of green chemistry, catalysis and materials design. This positive outcome offers a potential impact in future projects relating to water purification, biomass transformation and hydrogen storage and production.

Earth’s landmark greenhouse-icehouse transition at the Eocene Oligocene Transition (EOT) is arguably one of the most important climatic events in geological history. The dominant global geochemical signature of this dramatic shift in Earth’s climate (approximately 33.7 million years ago), a 1.2 - 1.5%o increase in the stable oxygen isotope ratio (d18O) of benthic foraminifera, represents a significant period of global cooling that occurred contemporaneously with the initiation of widespread Antarctic glaciation. The EOT represents the first establishment of a widespread, continental-scale, somewhat stable ice sheet on Antarctica and yet significant debate remains as to the forcing mechanism responsible for this substantial perturbation marking the end of the Eocene greenhouse world. Initiation of the step-wise shift in d18O occurred during an interval of low eccentricity and low-amplitude change in obliquity; an orbital configuration considered the ultimate trigger for glaciation at the EOT and the pacemaker for subsequent ice sheet growth. However, some other forcing mechanism(s) must have been important in conditioning the climate leading up to the EOT as these orbital configurations are found at other points in geological history where such large-scale changes in climate are absent. The overall aim of this thesis is to explore the evolution of temperature, ice volume and ocean circulation, the interactions between these key climatic parameters and the relative importance of different forcing and feedback mechanisms across the EOT. This thesis will place particular emphasis on paleoceanographic changes that occurred in the Atlantic Ocean region across this interval and their subsequent impacts. To this end, multiple records of foraminiferal stable isotopes and trace elements, and fish teeth neodymium isotopes are presented from sediment cores largely within the Atlantic Ocean or subject to its influence at the EOT. Findings of this thesis suggest a fascinating link between deep water formation in the North Atlantic Ocean and Antarctic ice sheet dynamics at the EOT. A new highresolution eNd record derived from fossil fish teeth at ODP Site 1263 (Walvis Ridge) in the South Atlantic provides evidence for a significant strengthening of Northern Component Water (NCW), a paleo pre-cursor to North Atlantic Deep Water (NADW), at 34.7 Ma one million years prior to the onset of the EOT. The increasing influence of northern-sourced deep waters, and associated cross-hemisphere heat piracy, provided optimal conditions for landmark climate change prior to the occurrence of the orbital parameters considered to be the ultimate trigger of the EOT. From this point on, NCW played a significant role in the distribution of heat and salinity within the Atlantic Ocean basin and is likely partly responsible, along with enhanced production of Antarctic Bottom Water (AABW) due to Antarctic glaciation, for the interhemispheric temperature asymmetry documented within this thesis. Benthic foraminiferal Mg/Ca-derived bottom water temperatures from IODP Site U1406 (Newfoundland Sediment Drifts) in the North Atlantic show a much lesser degree of cooling in the high northern latitudes when compared to their southern counterparts; in line with previous evidence from records of sea surface temperature (SST). Benthic foraminiferal trace element data from IODP Site U1406, along with ODP Site 925 (Ceara Rise) in the Equatorial Atlantic, demonstrate a regional, transient excursion in primary productivity that begins coeval with Antarctic glaciation at the EOT. Arctic Ocean continental shelves served as a nutrient-rich source fuelling the III Cardiff University Amy Sparkes productivity pulse in the Atlantic at the EOT when glaciation-induced sea level fall exposed organic-rich shelf sediment nutrients to weathering. This new source of bioavailable nutrients was efficiently distributed through the North Atlantic region by surface water overflows between the Greenland and Norwegian Seas and the North Atlantic causing increased primary productivity and associated export production leading to a steepening of the overall decline in pCO2 and hence acting as a positive feedback on Antarctic Ice Sheet (AIS) growth. Overall this thesis makes significant strides in clarifying the timeline of key climatic events in the Atlantic Ocean in the lead up to and across the EOT and highlights the importance of the influence of the Arctic Ocean and North Atlantic in modulating climate and ocean chemistry at the EOT.

In this thesis, high-resolution two- and three-dimensional seismic reflection datasets are used to examine the Quaternary Naust Formation on the mid-Norwegian continental shelf and slope, both at a high level of detail and over a huge areal extent of over 150,000 km2. First, the analysis of broad-scale margin architecture demonstrates the gradual development and increase in number of cross-shelf troughs produced by past ice streams that periodically drained the growing and decaying Fennoscandian Ice Sheet since approximately 1.5 M.y. ago. The development and intensification of focused ice flow from about 0.8 M.y. ago resulted in enhanced erosion on the shelf and increased sediment flux to the adjacent continental slope, with rapid shelf edge progradation and associated changes in margin architecture. The structural high of the Vøring Plateau, characterised by initially low (1-2º) slope gradients and reduced accommodation space, exerted a strong control over the long-term architectural evolution of the margin. Slope sediment fluxes were higher in the Vøring Plateau area, having increased up to 32 km3 k.y.−1 over the Quaternary compared to the maximum of 7 km3 k.y.−1 in the neighbouring sectors of the slope, which were characterised by steeper gradients (3-5º), more available accommodation space and smaller or no palaeo-ice streams on the adjacent shelves. Second, submarine glacial landforms found on the 500-km long mid-Norwegian continental shelf allow the reconstruction of the ice-sheet configuration over several Quaternary glacial-interglacial cycles. Evidence of iceberg ploughmarks found within the earliest Quaternary Naust surfaces documents a marine-terminating, calving Fennoscandian Ice Sheet margin extending periodically onto the mid-Norwegian shelf since the earliest Quaternary. Buried subglacially-produced mega-scale glacial lineations and ice-marginal grounding-zone landforms show the changing locations of fast-flowing ice streams as well as areas of slow-flowing ice, indicating dynamic ice-sheet behaviour and drainage variability on millennial timescales. The identification of the first buried glacitectonic hill-hole pair, as well as a few small channels formed both subglacially and at the margin of an ice-sheet, demonstrate complex, highly spatially and temporally variable ice-sheet subglacial thermal structure. Third, Quaternary sedimentary processes both down and along the continental slope are examined. Identification of more than 300 buried slope landforms provides a process- based palaeo-environmental reconstruction. The early Quaternary slope record (2.7-0.8 M.y. ago) is dominated by channels, indicating glacimarine sedimentation influenced by dense bottom-water flow and turbidity currents. The middle-late Quaternary (0.8-0 M.y. ago) slope succession shows a transition to dominance of glacigenic debris-flows delivered by progressively more erosive ice streams. This broad-scale palaeo-environmental shift coincides with the intensification of Northern Hemispheric glaciations, highlighting first- order climate control on the sedimentary processes on high-latitude continental slopes. In addition, individual sediment drifts found within different parts of the slope throughout the Naust Formation stratigraphy show the persistent influence of the North Atlantic Current over the Quaternary. Rapid formation of a large sediment drift (i.e., 720 km3 of accumulated sediment over the last 240 k.y.) located on the slope off Suladjupet cross-shelf trough emphasises how a combination of abundant glacially-derived sediment and its consequent delivery by alongslope processes may exert considerable influence on continental margin morphology over geologically short timescales. Finally, the Quaternary development of the North Atlantic Current is examined from evidence of past iceberg drift. Over 7,500 buried linear and curvilinear depressions interpreted as iceberg ploughmarks were identified and analysed within the Quaternary Naust Formation. The wide geographical distribution of ploughmarks suggests unrestricted iceberg drift and an open Norwegian Sea during the periods of iceberg calving since the early Quaternary. Ploughmark trajectory analysis demonstrates that the ocean current circulation, now dominated by the northeasterly flowing North Atlantic Current, has largely persisted throughout the Quaternary, with potential short-lived current reductions possibly related to major phases of iceberg discharge and/or meltwater pulses from the Fennoscandian Ice Sheet during the middle and late Quaternary.

For a multi-dimensional, partially observed diffusion process model with unknown drift and variable-independent diffusivity, we construct a composite methodology to perform Bayesian inference for the coefficients. Recent development of non-parametric Bayesian estimation of the drift has been restricted to dimension one, since the local time process is unavailable in the multi-dimensional case. We involve the empirical measure instead and show that the drift likelihood has a quadratic form, which allows a conjugate Gaussian measure prior whose precision operator is chosen to be a high order differential operator. We detail a computationally efficient pseudo-spectral method for solving the posterior mean, and describe how inference for the drift can be constrained to allow only conservative drifts. We also adapt a Langevin MCMC approach to sampling from diffusion bridges as a data augmentation scheme. To sample from the diffusivity, we specify an Inverse Wishart prior and implement a random walk Metropolis-Hastings algorithm. Evaluation of model fit for diffusion processes historically involved frequentist goodness-of-fit testing for fully parametric null models. We extend an existing transition density-based omnibus test to the null model case with non-parametric drift. We study the finite-sample behaviour of the test statistic and show that existing asymptotic results are inappropriate for settings involving real data. We implement the Bayesian discrepancy p-value to complement our inference methodology. With the goal of model improvement in mind, we describe how outlier removal and systematic sub-sampling of the data can be beneficial.

Matter-wave interferometry has enabled high precision measurements of inertial forces such as gravity and the Coriolis force. This is facilitated by the long-term stability of the physical properties of atoms and lasers. Recent experiments have demonstrated the operation of portable, robust sensors using atom interferometry. This has potential uses in the context of inertial navigation, where conventional devices suffer from long-term drifts due to bias instability. Furthermore, determining position via dead reckoning requires minimisation of dead time between measurements. This thesis presents the development of an atom interferometer for measuring horizontal accelerations. In this configuration, gravity induces motion across the laser wavefront, which constrains the tolerable level of wavefront distortions. Effective control of the experiment allows the interferometer to be operated at a rate of 4 Hz. A cold ensemble of 10^6 atoms in the same internal state is prepared in 150 ms. The interferometer operates using a sequence of three laser pulses separated by T= 25 ms to achieve sensitivity to horizontal accelerations. Combining this with a classical accelerometer provides a method of correcting for vibration-induced noise, as well as determining the interferometer fringe order. After an integration time of 40 s, the sensitivity to horizontal accelerations is better than 3^-6 m s^-2. Effects which limit this sensitivity are discussed.

This dissertation is dedicated to studying certain systems of two different species that interact with each other both locally and nonlocally. The systems under consideration are given as a combination of three contributions - nonlinear and nonlocal drifts that model the self-interactions and cross-interactions, re- spectively, between the agents of both species, cross-diffusion terms that de- scribe the dispersal of both species either due to an intrinsic urge to avoid over- crowding or due to size-exclusion effects, and cross-reaction terms that govern the birth and death processes within both subpopulations. These systems typ- ically arise in biomedical or physical contexts and display a variety of fascinat- ing behaviours such as self-sorting phenomena with a rich variety of patterns exhibiting regimes of segregation or mixing. While their one-species counter- parts are well-understood, coupled systems tend to have a higher complexity as many techniques that work for single equations fail in the case of coupled systems. With the results of this dissertation we add new insights to the current discourse of cross-interacting systems. For a certain choice of interaction potentials we provide explicit stationary states and travelling pulse solutions and we propose a numerical scheme whose solutions agree well with the analytical solutions. For a related model, the finite volume scheme is proven to converge. Besides, we prove and generalise an existence result for a certain class of reaction-cross- diffusion systems. Last we provide an existence result for a purely nonlocal interaction system with Newtonian interactions.

Understanding how the Meridional Overturning Circulation (MOC) might change in response to anthropogenic climate change has important repercussions for predictions of surface climate and the carbon cycle, but our ability to interpret future changes in the context of natural variability is limited by the short observational record (approximately 15 years). Key insights into the temporal variability of the MOC can be gained from geochemical tracers (e.g. carbon isotope ratios, δ13C and ∆14C) in geological archives. However, interpreting proxy records is complex because the isotopes respond to both physical and biogeochemical processes. Isotope-enabled models enable us to directly compare simulated and observed values, and investigate plausible mechanisms for the measured signals. Nonetheless, carbon isotopes are not routinely included in numerical climate models because of the computational cost of fully spinning up the deep ocean circulation and the marine carbon cycle (which requires run lengths between 5000 and 15,000 years). This thesis uses carbon isotopes to investigate ocean circulation and the marine carbon cycle in FAMOUS, a fully coupled atmosphere-ocean General Circulation Model that offers a unique balance between speed and complexity. Using the most recent published generation of the model, this study demonstrates that small regional salinity drifts (that occur because of inaccuracies in the formulation of the hydrological budget) can lead to significant changes in the representation of the MOC in multi-millennial climate simulations, even under constant pre-industrial boundary conditions and when the global hydrological budget has been forcibly closed. An earlier generation of the model, which provides a more accurate and stable representation of the pre-industrial MOC, is therefore used for the implementation and validation of a new carbon isotope scheme (13C and 14C). The simulated δ13C distributions capture the physical and biogeochemical behaviour of the model well, but are offset from observed values because of inaccuracies in the biological pump and the large-scale ocean circulation. The ∆14C tracer is less sensitive to these biases and shows good agreement to observations, both spatially and temporally, which demonstrates the skill of the model in representing carbon uptake and transport. Radiocarbon ages are typically interpreted in terms of ventilation, but comparing the simulated 14C ages to idealised water ages suggests that 14C is only a good ventilation tracer in well-mixed regions, where the physical component of the solubility pump is a more dominant control on dissolved inorganic carbon distributions than the chemical component. The local balance between physical and biogeochemical processes should therefore be considered when interpreting ∆14C in proxy records to avoid drawing erroneous conclusions about palaeocean circulation. Overall, this study demonstrates the utility of including carbon isotopes in numerical climate models: it aids our interpretation of geochemical tracers in geological archives, and provides a sensitive and holistic tuning diagnostic for evaluating and improving model performance.

This thesis describes the stimuli-responsive nature of metal-organic frameworks to light, solvent introduction and solvent loss. Chapter 1 introduces metal-organic frameworks, highlighting the different components of the materials, and reviewing historic work into the development of stimuli-responsive MOFs. Approaches to post-synthetic modification (experimentally undertaken in Chapter 2) are introduced. Specialist experimental techniques and various approaches to the analysis of infrared spectra (used in Chapters 3 and 4) are also defined. Chapter 2 describes how optical spectroscopy and microscopy has been employed to track fluorescent guest molecules through framework pores. As part of this work, size-optimised single crystals of NOTT-100 and Sc2BDC3 were synthesised. In the process of investigating crystal size, damage to crystals upon exposure to the SEM sample chamber vacuum was observed. The effect of common laboratory solvents on crystal quality was qualitatively investigated, and solvent acceptor number and molar volume were found to correlate to crystal damage. Reaction conditions for the post-synthetic modification of frameworks with a monocarboxylate-functionalised dye were established through the use of UV-visible (UV-VIS) absorption spectroscopy and confocal laser scanning microscopy (CLSM). Frameworks were post-synthetically modified with both a spirooxazine-based and a hydrazone-based photoswitch. Solid-state photoswitching of the spirooxazine-based photoswitch was observed during in situ CLSM experiments and on 290 nm irradiation by UV-VIS-diffuse reflectance spectroscopy. The adsorption capabilities of modified materials were measured using N2 sorption isotherms, and modification of materials with dyes was found to hinder the adsorption of guests into frameworks in all cases. Chapter 3 investigates the diffusion of therapeutic agents from MOF single crystals and bulk powders using in situ infrared microscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). A sophisticated experimental technique was devised to establish the kinetics of guest loss from MOFs into a volatile solvent environment. The loss of caffeine from MIL-68(In) into acetonitrile (MeCN) was tracked at six temperatures, and an Ea of +144 kJ mol-1 (calculated error < 1 kJ mol-1) determined for the diffusion process. The loss of carbon monoxide (CO) from fully-desolvated NOTT-100 was tracked at low temperatures. Analysis of spectra confirmed the loss of CO from different Cu-paddlewheel sites to be interconnected processes, and not occurring in isolation from one another. Chapter 4 employs IR microspectroscopy to probe the structural rearrangement of a solvent-switchable, breathing framework, SHF-61. Crystallographic experiments have reported that desolvation from CHCl3 and DMF led to open- and closed-pore structures respectively. In this thesis, examination of the (NH) stretch using IR microspectroscopy was able to track the time-resolved pore-opening process during resolvation with DMF, identifying four states of the pore structure and monitoring their relative abundancies during the resolvation experiment. The open-pore structure was resolvated with and subsequently desolvated from: CHCl3, cyclopentanone and DMF. The rate of resolvation and subsequent desolvation was elucidated, using only (NH) stretches and respective solvent bands. The response of the material to CO2 loading was investigated, and a gas uptake isotherm shape was recreated for one single crystal of material.

This thesis uses the high-quality Poseidon 3D seismic volume, 2D seismic data and well data from the Browse Basin, offshore Northwest Australia. It investigates the initiation, growth and demise of the Miocene Oliver Limestone Formation to understand the relative importance of different exogenic and endogenic controls on carbonate growth patterns. This thesis then goes on to assess the impact of scale relationships, associated with different datasets, on the characterisation of carbonate reservoirs. This is achieved through qualitative and quantitative interpretation of seismic data, outcrop and numerical models. The initiation of a carbonate system within the Browse Basin was first investigated to propose a new evolutionary model for Northwest Australia and to assess the relative significance of fluid flow and fault topography to carbonate build-up development. Faults and fluid flow features were analysed using detailed qualitative and quantitative seismic interpretation. The results demonstrate a positive correlation between fluid flow and the generation of pinnacle features on the Miocene sea floor of the Browse Basin. These pinnacle features are explained in this thesis as the first patch reefs formed in association with mud volcanoes or methanogenic carbonates. They are considered as key features precluding the growth of the larger isolated carbonate buildups. This thesis postulates that pinnacle features above fluid-flow conduits demonstrate a valid seep-reef relationship and are refined diagnostic features for understanding fluid flow through geological time. The geometric and depositional responses of isolated carbonate build-ups to Miocene sea-level change and regional tectonics, was investigated to derive their relative significance on growth patterns and carbonate facies distribution. Seismic stratigraphy and facies associations were interpreted using 3D seismic and borehole data from the Browse Basin, Northwest Australia, combined with outcrop information from the Cariatiz Reef in Southeast Spain. Results documented Messinian structural partitioning to occur across the Browse Basin, with deformation associated with plate collision focused on preferentially oriented faults, i.e. only influencing carbonate buildup evolution at a local scale. Seismic attribute analyses proved highly effective in interpreting carbonate facies, but when compared with outcrop information from Southeast Spain, this same attribute data was limited to features larger than 17 m vertically and 50 m horizontally. Thus, estimations of reservoir potential are significantly underestimated when only based on the interpretation of seismic data. The final part of this thesis investigates the demise of carbonate build-ups in the Browse Basin so as to determine the relative significance of endogenic and exogenic processes in drowning carbonate factories. Growth patterns and drift deposits where interpreted using the high-resolution Poseidon 3D seismic survey and additional 2D seismic lines. The relative significance of different geological processes was investigated using numerical stratigraphic forward modelling (CarboCAT) to test different scenarios based on seismic interpretation and current literature. Results showed that the subsidence rates currently proposed in the literature generated accommodation space in the Browse Basin, but were of insufficient magnitude to drown the carbonate factories. Eustatic sea level did not influence large-scale growth patterns or drowned the build-ups. Hence, this thesis postulates that current activity (with associated deposition of sediment drifts) and excess nutrient supply were key to the drowning of carbonate build-ups in the Browse Basin. These two processes are often overlooked when interpreting the demise of carbonate build-ups on equatorial margins around the world. The overall implications of this work are as follows: 1) Fluid flow should be considered as an important endogenic control on carbonate build-up initiation and therefore the presence of carbonate build-ups in areas of hydrocarbon generation may act as an indicator of seal leakage; 2) Structural partitioning within the Browse Basin had a significant impact on carbonate growth patterns. Thus it is important to consider that localised tectonics can induce significant variability in growth patterns and, therefore, reservoir distribution within a basin; 3) Seismic attributes are a key tool in aiding the delineation of reservoir facies and processes generating secondary porosity (e.g. karsts). As such, they can aid the generation of increasingly robust geological models and thus reduce exploration uncertainty; 4) The primary cause of carbonate build-up demise during the Late Miocene is environmental deterioration as opposed to tectonic or eustatic sea level; 5) Numerical modelling (CarboCAT) proved an effective tool in testing qualitative interpretations derived from seismic interpretation. The numerical modelling completed in this work showed value in predicting reservoir distribution and carbonate growth patterns, parameters that can guide exploration on a basin scale, as well as aid interpretation at an inter-well scale to reduce exploration risk.

The conventional design philosophy of bridges allows damage in the pier through yielding. A fuse-like action is achieved if the bridge piers are designed to develop substantial inelastic deformations when subjected to earthquake excitations. Such a design can avoid collapse of the bridge but not damage. The damage is the plastic hinge formation at location of maximum forces and stresses that can lead to permanent lateral displacement. This can impair traffic flow and cause time consuming repairs or in some cases even complete demolition of the bridge. Rocking can act as a form of isolation by not fixing the foundation to the ground but to allow it to uplift and thus act as a mechanical fuse, limiting the forces transferred to the base of the structure. Rocking isolation enhances the seismic resistance of the structure and their post-earthquake serviceability. In this context, this research proposes a novel rocking isolation technique which uses elastomeric pads incorporated beneath the footing of the bridge piers and external restrainer in the form of shape memory alloy bar (SMA). The rocking mechanism is achieved by restricting the horizontal movement of footing by providing stoppers at all sides of footing. The pads are designed to remain elastic without allowing their shearing. The pier, the footing and the elastomeric pads are supported on concrete sub base which rests on firm strata such as stiff soil, hard rock or on pile cap. By performing nonlinear dynamic time history analysis and nonlinear pushover analysis, the proposed bridge with the novel resilient pier foundation is compared against an existing conventional bridge on spread foundation as well as on pile foundation. The proposed pier rocking on elastomeric pads and external restrainer has been found to have good re-centering capability and negligible residual drifts during earthquakes. It is also found that by allowing the foundation to uplift, the forces at base of pier are effectively reduced but the horizontal displacements at pier top are increased. However, these excessive pier displacements can be controlled by the sacrificial external SMA bars attached from the footing to the base slab of the foundation.

This thesis comprises a novel and poetics exploring how creative writing practice can be influenced by engaging in psychogeographic studies of landscapes containing nuclear power stations. The focus of this research is the Exclusion Zone surrounding the Chernobyl Nuclear Power Station in Ukraine and the landscape around Wylfa Nuclear Power Station in North Wales. The novel explores how embodied experience of landscapes containing nuclear power production affects emotional and behavioural responses in the characters. It is designed as a contiguous narrative between the two places, following one sister's journey to and through the Exclusion Zone, and the remaining sister's reevaluation of her response to nuclear power at home. This structure enables thematic links and comparisons between the contaminated and heavily restricted landscape that exists following the Chernobyl disaster, and the farming community around the still functional Wylfa. The poetics is an autoethnographic study examining how my own relationship with nuclear landscapes informs my creative actions. In Part One I consider Guy Debord's definition of psychogeography alongside Eudora Welty's essay on place in fiction in relation to my writing processes. Examination of Maurice Merleau-Ponty's theories of embodied perception, and the writing of Robert Macfarlane, identifies how landscape is read physically and sensually, as well as visually, and how this informs my methodology. Part Two provides a detailed investigation of my psychogeographic practice within the landscapes of Wylfa and Chernobyl, with specific focus on those aspects of the novel that were influenced by this practice. In applying Debord's critique of 'the Spectacle' to the Exclusion Zone I discuss how engaging in dérives - drifts through multiple ambient spaces - facilitated the gathering of embodied knowledge for the novel. This thesis analyses the ways in which landscape forms identity as much as identity informs perceptions of landscapes, and how this symbiosis shapes the narrative and characters in Borderlands. It exemplifies how psychogeography can be applied to rural irradiated spaces to form new understandings of emotional and behavioural responses to nuclear power, and how this can inform creative actions.

Remote powering over the Ethernet (including PoE, PoE+ and PoE++) is currently trending as a cost-effective option to power networked devices using balanced twisted pair cabling. As technology advances and Ethernet penetration grows, more devices are deployed, thereby increasing the cabling density to support these devices. Power delivery through Ethernet cables has numerous benefits, including cost and space saving. However, concurrent high-power transmission and installation conditions could induce local heating, and thus, thermal variation may occur in the cable bundles, and these can be exacerbated by the installation conditions, and sometimes by extreme weather conditions. Over a long time, all these could modify the cable properties, thus affecting the performance of the cabling system and thereby impacting the Ethernet signal integrity. Although Joule heating of the cable bundle is primarily assumed to be concomitants of current transmission through the cable, several fundamental questions around these processes are not yet fully answered. They include: Do cable heating and thermal variations influence the designed transmission parameters of the cable? If yes, how can the cause(s) and effects be accurately measured and reliably validated? In answering some of these questions, a series of experiments were developed and adopted to (1) assess cable bundle heating (2) assess the performance of Balanced Twisted Pair cables subject to repeated thermal variation, both within the specified operating range and beyond to account for the situations where high temperature and localised heating might stress the cables beyond the designed or expected levels (3) assess the performance of Ethernet cable dielectrics to understand some of the root causes of Ethernet cable performance degradation. The outcome of the research showed that high power (100 watts) deployment over bundled and insulated unshielded Ethernet cables triggered an extremely high-temperature increase (~ 140°C) that resulted in mechanical failure of the cables' dielectrics and a short circuit between the copper conductors of the cables. Larger cable conductor size, screening of the twisted pair along with Fluoropolymers as the conductor insulation helped the shielded cables not to reach a point of failure when tested in the insulated environments and at high power levels even though there was a temperature rise on the cables. Moreover, repeated resistive and non- resistive heating have adverse effects on the electrical properties and transmission parameters of Balanced Twisted Pair cables, most notably in the first few cycles. The impact was more pronounced during the cooling phase than the heating phase. Also, the thermal impact was more accentuated in insulated operating condition than in ventilated operating condition. The electrical length of the cable measured by the tester decreased by 0.7 m 5 due to the effect of repeated non-resistive heating in an insulated environment and at a high temperature of ~120°C but decreased by 0.4 m with ~70°C in a similar insulated environment. Phase drifts in Balanced Twisted Pair cables were observed to be dependent on the combined effects of mechanical dimension, dielectric constant and frequency. Thermal variation caused a phase change in the Return Loss (RL) signal from 63° to 90°, from 90° to 135° and from 135° to 315° respectively. The RL performance of Category 6 U/UTP CoMmunications Plenum rated (CMP) cable failed at 20°C and recovered at 23°C initially, but after the electrical length of the cable had decreased, subsequent failure and recovery temperatures accelerated towards higher temperature (400C). Similarly, the transition temperatures of the bandwidth of the cavity loaded with the Fluorinated Ethylene Propylene (FEP) from the Category 6 U/UTP CMP cable accelerated during the prolonged thermal cycling. The maximum reduction in the RL value of Category 6A F/UTP cable due to the 40 thermal cycles conducted was observed to be 5 % per degree, whereas the maximum Insertion Loss (IL) increase was 5.8 % per degree. Moreover, for the 24 thermal cycles conducted on Category 6 U/UTP CMP cable, an increase in IL of ~8.3 % per degree was observed while RL decreased by ~6.8 % per degree. Using the Features Selective Validation technique, the comparison between the baseline performance and long-term performance of Category 6A F/UTP permanent link (PL) showed a fair agreement, which implies degradation in the performance of the cable. Furthermore, results showed that impedance varied significantly along the length of the cable due to localised heating of the cable. The impedance along the unheated sides of the cable reverted at every λ/2 (0.4 m) and λ/4 (0.2 m) but the impedance profile of the heated middle portion of the cable varied significantly. The results of the Scanning Electron Microscope revealed the deformation in the conductor insulation of a twisted pair sample. Furthermore, the adhesion of the twisted pair conductor insulation to its copper conductor was also observed to be affected near the end of the twisted pair sample. Connector impedance mismatch was observed to be severe on the split pair pins (pair 3,6) than other pairs in the cable. The connector impedance mismatch also dominated the Near End Crosstalk (NEXT) loss at frequencies around 35 MHz. The repeated heating of the cable to a higher temperature of 1200C caused the loss of the PL at room temperature and a DC contact resistance issue which of course resulted in poor intra-pair resistance unbalance between the split pair. The Transverse Conversion Loss (TCL) and Equal Level Transverse Conversion Transfer Loss (ELTCTL) of Category 6 U/UTP CMP PL revealed some imbalances in the structure of the twisted pairs. Also, the equivalent differential mode noise voltages for the TCL values of the cable revealed a voltage spike following the decrease in the electrical length of the cable. More also, Crosstalk performance between the longest and shortest pair in the Category 6A 6 F/UTP cable was also observed to be better due to the heating of the cable in comparison to the crosstalk loss measured due to the cooling of the cable. Crosstalk performance of the portion insulated cables was initially worse during the first few heating and cooling cycles but improved afterwards. In addition, crosstalk, which was not initially present at the reference plane of the permanent link, was observed to increase rapidly from the point where the electrical length decreased. The increase in temperature to ~650C caused an accentuated frequency shift in the resonance of the FEP, which is the probable cause of the immediate performance degradation of the Category 6 U/UTP CMP cable. The dielectric constant of the extracted FEP rod sample from Category 6 U/UTP CMP cable increased as a consequence of prolonged thermal cycling, particularly during the cooling phase, which also suggests the root cause of the poor RL performance observed during the cooling phase. The increased loss tangent of the FEP during thermal cycling also indicates that IL performance degradation of the Ethernet cables will increase during the heating and cooling process in Ethernet cables. Also, on a long-term, IL performance will drift due to thermal cycling. Furthermore, various signal phase transitions were recorded during the heating and cooling of the cable and its dielectric due to the different behaviour of the molecular transitions. As a result, an echo of RL was measured during the transition between the intermittent and prolonged thermal cycling of the cable, of which can be correlated to the spurious resonance, observed in the resonance of the FEP sample during the transition period. Thus, it could be inferred that immediate and longterm effects of thermal variation influence the designed electrical properties and transmission parameters of Balanced Twisted Pair cables. Also, an immediate and long-term effect of thermal variation on the conductor insulation of the cable has a direct effect on the performance of Balanced Twisted Pair Cables.

There are a range of environmental and industrial applications to capturing carbon dioxide from gas mixtures. Currently, materials being used in these applications bind carbon dioxide too strongly for practical purposes, such that they require large amounts of energy to be regenerated for reuse. Highly porous materials called metal-organic frameworks (MOFs) could serve much more effectively as carbon-capturing materials, as they suck up large amounts of carbon dioxide gas at pressures and temperatures that are nearly ideal for carbon-capture applications. Moreover, they require much less energy than current materials to release the carbon dioxide and be regenerated. Additionally, many different structures can be created fairly easily, so scientists are on the hunt for the ideal carbon-capturing MOF. In this thesis we study Mg-MOF-74, a particularly promising metal-organic framework material for separating carbon dioxide from gas mixtures. We use infrared spectroscopy to probe the interactions between the Mg-MOF-74 host and both carbon dioxide and methane. By shining infrared radiation on Mg-MOF-74 with gases trapped in it and looking at which frequencies of radiation are absorbed by the bound gases, we can learn about the binding nature of the framework. This in turn helps us to better understand the properties are are preferable in metal organic frameworks, and will aid chemists in fabricating new structures that are ideal for carbon-capture and other applications.

In this thesis we examine the hydrogen storage properties of four different materials. Because of the global climate crisis and the growing realization that petroleum resources are limited, there has been a strong push to find alternative means of energy storage. At the forefront of this push is the hydrogen economy, the idea that hydrogen gas is a bountiful, clean, alternative means of energy storage. One step towards realizing the hydrogen economy is finding a practical means of hydrogen storage.The conventional methods of hydrogen storage are in high-pressure gas cylinders or as a liquid. Both of these methods are impractical for energy storage purposes. The gas cylinders are very massive and so hold little hydrogen for their weight; and hydrogen only liquefies at -251.9° C (-421.4° F), which imposes impractical limitations on its use. The most promising alternative storage option is finding a material that traps a large quantity of hydrogen at room temperature and atmospheric pressure.At the current time, there is no known material that is a practical option for hydrogen storage. In this thesis we use infrared spectroscopy to investigate the behavior of the hydrogen inside the material and the interaction between the trapped hydrogen and the material . By refining our understanding of this interaction, we can predict what might make good storage materials. Currently, theoretical models are unable to predict energies that are correct within 25%. We successfully explain the observed behavior of the trapped hydrogen in the four materials. Our investigation also provides a wealth of data that can be used to calibrate theoretical models. These results will help guide us towards new materials that have greater potential to be viable storage alternatives.

Bridges often serve as key links in the local and national transportation networks. Any bridge closures can have severe costs not only in the form of repair or replacement, but also in the form of economic losses related to medium- and long-term interruption of businesses and disruption to the communities. In addition, continuous functionality of bridges is very important after any seismic event for emergency response and recovery purposes. Considering the importance of these structures, the associated structural design philosophy is shifting from collapse prevention to maintaining functionality in the aftermath of moderate to strong earthquakes (Resiliency). Moreover, the associated construction philosophy is being modernized with the utilization of accelerated bridge construction (ABC) techniques to reduce impacts of construction work on traffic, society, economy and on-site safety during construction. This dissertation presents two bridge systems targeting the aforementioned issues. A combined numerical and experimental research was undertaken to characterize the seismic performance of these bridge systems. The first part of the study focuses on the structural system level response of highway bridges that incorporate a class of innovative connecting devices called the “V-connector”, which can be used to connect two components in a structural system, e.g., the column and the bridge deck, or the column and its foundation. This device, designed by ACII, Inc., results in an isolation surface at the connection plane via a connector rod placed in a V-shaped tube embedded into the concrete. Energy dissipation is provided by friction between a special washer located around the V-shaped tube and a top plate. Because of the period elongation due to the isolation layer and the limited amount of force transferred by the relatively flexible connector rod, bridge columns are protected from experiencing damage, leading to an improved seismic behavior. The V-connector system also facilitates the ABC by allowing on-site assembly of prefabricated structural parts including those of the V-connector. A single-column, two-span highway bridge located in Northern California was used for the proof-of-concept of the proposed V-connector protective system. The V-connector was designed to result in an elastic bridge response based on nonlinear dynamic analyses of the bridge model with the V-connector. Accordingly, a 1/3-scale V-connector was fabricated based on a set of selected design parameters. A quasi-static cyclic test was first conducted to characterize the force-displacement relationship of the V-connector, followed by a hybrid simulation (HS) test in the longitudinal direction of the bridge to verify the intended linear elastic response of the bridge system. In the HS test, all bridge components were analytically modeled except for the V-connector, which was simulated as the experimental substructure in a specially designed and constructed test setup. Linear elastic bridge response was confirmed according to the HS results. The response of the bridge with the V-connector was compared against that of the as-built bridge without the V-connector, which experienced significant column damage. These results justified the effectiveness of this innovative device.The second part of the study presents the HS test conducted on a 1/3-scale two-column bridge bent with self-centering columns (or broadly defined as “resilient columns” in this study) to reduce (or ultimately eliminate) any residual drifts. The comparison of the HS test with a previously conducted shaking table test on an identical bridge bent is one of the highlights of this study. The concept of resiliency was incorporated in the design of the bridge bent columns characterized by a well-balanced combination of self-centering, rocking and energy dissipating mechanisms. This combination is expected to lead to minimum damage and low levels of residual drifts. The ABC is achieved by utilizing precast columns and end members (cap beam and foundation) through an innovative socket connection. In order to conduct the HS test, a new hybrid simulation system (HSS) was developed, utilizing commonly available software and hardware components in most structural laboratories, namely, a computational platform using Matlab/Simulink (MathWorks, 2015), an interface hardware/software platform dSPACE (2017), and MTS controllers and data acquisition (DAQ) system for the utilized actuators and sensors. The operation of the HSS was verified using a trial run without the test specimen. In the conducted HS test, the two-column bridge bent was simulated as the experimental substructure while modeling the horizontal and vertical inertia masses and the corresponding mass proportional damping in the computer. The same ground motions from the shaking table test, consisting of one horizontal component and the vertical component, were applied as input excitations to the equations of motion in the HS. Good matching was obtained between the shaking table and the HS test results, demonstrating the appropriateness of the defined governing equations of motion and the employed damping model, in addition to the reliability of the developed HSS with minimum simulation errors. The small residual drifts and the minimum level of structural damage at large peak drift levels demonstrated the superior seismic response of the innovative design of the bridge bent with self-centering columns. The reliability of the developed HS approach was the motivation of a follow-up HS study focusing on the transverse direction of the bridge where the entire two-span bridge deck and its abutments represented the computational substructure while the two-column bridge bent was the physical substructure. This investigation was effectively utilized to shed more light on the system level performance of the entire bridge system with innovative bridge bent design beyond what can be achieved via shaking table tests, which are usually limited by large-scale bridge system testing capacities.

The means by which magnetic reconnection in Earth's space environment is observed is limited by current instrument technology and timing of satellite orbits. Imaging capabilities from a spacecraft platform are still developing, and in-situ measurements are confined to the spacecraft's orbit. The goal of this dissertation is to provide and apply methods by which the spatial extent of magnetic reconnection at Earth's magnetopause can be quantified. An accepted single value, or range of spatial extents of magnetopause reconnection has eluded the scientific community for over half a century. This dissertation provides two methods by which the spatial extent can be sampled. First, with the development of a CubeSat, the Cusp Plasma Imaging Detector (CuPID). CuPID is built with a wide field-of-view soft X-ray telescope to image the photons resulting from solar wind charge exchange between atmospheric neutrals and high charge-state solar wind ions. During magnetic reconnection at the magnetopause, solar wind ions are routed along field lines to Earth's cusps in the polar regions. In the magnetospheric cusps, these solar wind ions can penetrate deeper into Earth's neutral atmosphere, producing an observable signal for a low Earth orbiting satellite. The design of the CuPID mission and the calibrations of CuPID's instruments are presented. CuPID was launched in September 2021, but did not respond to commanding from the ground. Efforts to modify and improve the ground station led to the discovery of a probable root cause of failure with CuPID's flight radio. A second method of observing magnetic reconnection utilizes in-situ measurements of plasma populations and magnetic fields. The THEMIS mission, orbiting five satellites continuously since 2007, traverse the magnetopause nearly every orbit when their orbital apogee is on the dayside. When two spacecraft cross the magnetopause simultaneously and both observe features of magnetic reconnection, the spatial extent of reconnection is constrained by their spacing. Using statistics from 174 events of spacecraft conjunctions at the magnetopause, the spatial extent of reconnection as observed by THEMIS is on average 3,148 km. This study also investigates the processes by which magnetic reconnection is constrained, including plasma beta gradient drifts and position on the magnetopause flanks.