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Assessing the impact of new woodland creation on catchment hydrology and flood risk
Get PDFWoodland creation is a known broad measure used as part of nature-based solutions for
different catchments. Previous research studies have established the multiple benefits of
woodland creation related to more comprehensive catchment research. However, those
benefits have been researched on a broader catchment scale rather than on the small scales
that include cultivation practices. This created a lack of evidence for studies related to the
hydrology of cultivation techniques. This case study added unique values to researching
different cultivated areas (plough, excavation mounding and hand-screefing cultivation)
in Menstrie catchment, Scotland.
For this study, the cultivation techniques were monitored for two years regarding runoff
and sediment delivery at the field scale. Seven different plots (one unplanted plot, one
hand-screefing plot, three plough plots and two excavation mounding plots -P6, P7) were
monitored on microscale level (< 0.5 km2
). Furthermore, monitoring included surface
water level monitoring from two streams (Inch 1 and Inch 2) of the main water course in
the Menstrie catchment. For better understanding of hydrological behaviour data has been
analysed from dry (API30 ≤ 20 mm) and wet (API30 > 20 mm) weather perspective.
However, according to monitored data, the study distinguished differences between
runoff and sediment delivery from different cultivation plots and their effectiveness. On
sub-catchment level main findings highlighted forest cover importance. This clearly
showed that Inch 1 sub-catchment had lower values of runoff water than Inch 2 subcatchment for any weather conditions. Inch 2 sub-catchment had 25 % more grassland
cover than Inch 1 sub-catchment. On another hand, monitored cultivations plot and
unplanted plot discovered hydrology on microscale for dry and wet weather conditions.
Analysed data showed that runoff water will first in unplanted plot area, followed by
peaty based plough plot, hand-screefing plot, brown soil-based plough plots and
excavation mounding plots during dry weather conditions. On the other hand, the fastest
response for wet weather conditions will occur in unplanted plot area, plough plots,
lowland excavation mounding plot, followed by hand-screefing plot and upland
excavation mounding plot. Then, the highest amount of runoff for dry weather conditions
occurred in the case of unplanted plot, peaty soil-based plough plot and lowland
excavation mounding plot, since wet weather conditions had unplanted plot, handscreefing plot and lowland excavation mounding plot. However, those finding was associated with cultivation design, slope of catchment area, slope of channel, soil type
etc. However, the highest amount of sediment delivery refers to plough plots since hand
screefing plot and excavation mounding plots monitoring plots have experienced
significantly less sediment delivery. Those data have been analysed in connection with
precipitation, runoff peak and runoff volume.
Overall, this research defined hydrology and sedimentology of different cultivated areas
depending on main properties of monitored plots. Those findings can be improved by
further research in the same area
Optimisation of microscopic techniques to assess isolated islet characteristics
No full textIslets of Langerhans or pancreatic islets constitute ~2% of the mass of the human
pancreas and present on isolation as spheroids of 100-200 µm diameter. The 3D cellular
organisation of islets is specific to each species, and important for islet viability and
functionality. Isolated donor islets are used in transplantation for ameliorating Type I
diabetes in humans, however current techniques to assess islet viability are highly
specialised and not easily accessible in a non-clinical set up. The research in this thesis
aimed to create and optimise methodologies for multiple microscopic techniques and
analysis for isolated pancreatic islets. I found that live imaging of 3D intact pancreatic
islets has multiple challenges, one of the most important being techniques to efficiently
immobilise these organoid structures while retaining high-quality imaging and
flexibility in the experimental set-up. I developed a tailor-made hydrogel for pancreatic
islets and validated its use in live intact islets. The hydrogel was combined with
experimental and commercially available chemical dyes and enabled optimisation of the
analysis. Limitations in the labelling and imaging are discussed. Alternative dyes were
tested to label different structures as steps towards automated viability assessment of
isolated islets. New applications for an experimental dye to label alpha and beta cells
were tested in human islets. In pursuit of a better understanding of the insulin metabolic
pathways for its synthesis, maturation and release, a fluorescence timer tag was
designed and validated for its use in beta cell lines and pancreatic islets. This validation
was a multiple optimisation processes consisting of immunostaining and histology,
imaging analysis and characterisation in live beta cells. The thesis offers insight into
the complexities, opportunities and limitations offered by microscopic techniques in
islet assessment with the aim of enabling assessment of islet health before
transplantation and for research purposes
Towards full-scale autonomy for multi-vehicle systems planning and acting in extreme environments
Get PDFCurrently, robotic technology offers flexible platforms for addressing many challenging problems that arise in extreme environments. These problems’ nature enhances
the use of heterogeneous multi-vehicle systems which can coordinate and collaborate
to achieve a common set of goals. While such applications have previously been
explored in limited contexts, long-term deployments in such settings often require
an advanced level of autonomy to maintain operability.
The success of planning and acting approaches for multi-robot systems are conditioned by including reasoning regarding temporal, resource and knowledge requirements, and world dynamics. Automated planning provides the tools to enable intelligent behaviours in robotic systems. However, whilst many planning approaches and
plan execution techniques have been proposed, these solutions highlight an inability
to consistently build and execute high-quality plans.
Motivated by these challenges, this thesis presents developments advancing state-of-the-art temporal planning and acting to address multi-robot problems. We propose a set of advanced techniques, methods and tools to build a high-level temporal
planning and execution system that can devise, execute and monitor plans suitable for long-term missions in extreme environments. We introduce a new task
allocation strategy, called HRTA, that optimises the task distribution amongst the
heterogeneous fleet, relaxes the planning problem and boosts the plan search. We
implement the TraCE planner that enforces contingent planning considering propositional temporal and numeric constraints to deal with partial observability about
the initial state. Our developments regarding robust plan execution and mission
adaptability include the HLMA, which efficiently optimises the task allocation and
refines the planning model considering the experience from robots’ previous mission
executions. We introduce the SEA failure solver that, combined with online planning, overcomes unexpected situations during mission execution, deals with joint
goals implementation, and enhances mission operability in long-term deployments.
Finally, we demonstrate the efficiency of our approaches with a series of experiments
using a new set of real-world planning domains.Engineering and Physical Sciences Research Council (EPSRC) grant EP/R026173/
Non-Abelian gerbes with connections in higher gauge theory
Get PDFIn this thesis, we study some classical structures of the (2, 0)-theory within the
framework of higher or categorified gauge theory, overcoming several obstacles preventing the existence of a classical M5-brane model.
Firstly, we derive the complete cocycle description for non-Abelian higher principal bundles, or gerbes, with connections whose structure 2-group is a strict 2-group
with adjustment datum. We depart from the common fake-flat connections and employ adjusted connections, which is important for physical applications, especially
in the context of supergravity.
Secondly, we give a number of explicit examples; in particular, we lift the principal bundle corresponding to an instanton–anti-instanton pair to a string 2-group
bundle. Such string structures are believed to play the role of higher gauge groups
for self-dual strings in the (2, 0)-theory.
Thirdly, we present a six-dimensional N = (1, 0) supersymmetric higher gauge
theory modelled on string structures, in which self-duality is consistently implemented by physically trivial additional fields. The action contains both N = (1, 0)
tensor and vector multiplets and is non-trivially interacting. The tensor multiplet
part is loosely related to a recently proposed action by Sen that leads to on-shell
self-duality in an elegant way.James Watt Scholarshi
Optimisation potential of coordinated shared leadership in global virtual teams - an analysis of influencing factors the performance of international projects
Get PDFThis research study investigates how coordinated shared leadership can be implemented
to enhance the performance of global virtual teams (GVTs). The establishment of globally
distributed virtual teams is strongly driven in the automotive industry by the increasing
shift of software development tasks and competences to India. If companies miss or
underestimate this important organisational change towards virtual teams applying a
collaborative leadership style or the challenge of operating GVTs (e.g., the consideration
of cultural aspects), then they won´t be competitive in the future anymore. Based on this
issue in business, two research questions were derived from the existing literature to form
the focus for the data collection.
It is assumed that coordinated shared leadership has a positive effect on team performance
because a majority of researchers emphasised that shared leadership, when coordinated,
significantly increases performance. Previous work analyses individual conditions and
structural underpinnings of shared leadership or GVTs. Only some studies consider the
importance of coordinated shared leadership. However: to date, there is no holistic
understanding of how these factors interact and, by adjusting, which of these factors can
improve team performance. This study aims to close this gap by focusing on the most
influential conditions and structural foundations and how they interrelate.
Based on the selection of GVTs from the automotive industry, a case study method was
adopted as the main data source for this research. In two case studies, semi-structured
interviews were conducted with experienced team members and leaders of GVTs to
answer the research questions. The research design is based on the procedures and quality
controls associated with qualitative research methods within the critical realist paradigm.
In this research, the case study approach serves to combine the theoretical findings from
the literature review with the insights from the interviews. The main objective of this
study is to explore coordinated shared leadership in GVTs, specifically through the case
study of German-Indian software development teams in the automotive sector. This
research contributes to a holistic understanding of which conditions and structural
underpinnings can contribute to improving team performance and to what extent. By
applying the recommendations compiled in this study, software projects in the automotive
sector can be completed faster, more cost-effectively, and with higher quality
Improved oil recovery by low salinity water injection at larger scales
Get PDFLow Salinity Water Flooding (LSWF) has demonstrated its capacity to expedite oil
production in certain scenarios, prompting its consideration as a potential method for
Improved Oil Recovery (IOR). Despite its economic significance, the field application
of this method for improved oil recovery remains limited. This is primarily due to a lack
of understanding about pore-scale mechanisms. Much of the existing literature has
concentrated on establishing a consistent rationale for incremental oil recovery across
various scales, from sub-pore to core scales.
Several mechanisms have been proposed, which rely on the interaction between rock
materials and aqueous phases, as well as between aqueous phases and crude oil.
However, there are counter-examples in the literature that challenge some of these
proposed mechanisms. Among these mechanisms, the theory of microdispersion
formation resulting from reduced brine salinity offers a satisfactory and consistent
explanation for IOR. The theory effectively explains differences in oil recovery across
various reservoirs by accounting for the different capabilities of crude oil samples to
form microdispersions.
Despite advances, significant challenges persist in upscaling low salinity water injection
for field application. These challenges stem in part from insufficient attention devoted
to this area of research. The present research program aims to systematically and
comprehensively identify and address these challenges. The outcomes of this study will
expand upon the extensive understanding of low low-salinity water injection method.
These challenges are mentioned in following.
The relationship between recovery and wettability alteration isn't completely clear due
to the complexities involved in studying wettability changes caused by low salinity
water. Most investigations in this area focus on sub-pore measurements, overlooking oil
phase connectivity and pore geometry effects. Even core-scale tests can't fully replicate
the phenomena within porous media. To address the mentioned challenge, this program
introduces a novel wettability index based on chromatographic separation of two water-soluble tracer substances. This in-situ measurement considers oil phase connectivity,
pore geometry impact, and faithful simulation of porous media phenomena. Using this
method, different systems with varying microdispersion ratios for wettability changes is
evaluated. It is noticed that the formation of microdispersions strongly influences wettability, a relationship that's been convincingly demonstrated. Furthermore, a link
between wettability alteration and oil recovery in the process has been established.
Furthermore, the mixing of injected low salinity water with the resident high salinity
water in the reservoir might lead to a reduction in the salinity gradient at the reservoir
scale, ultimately negatively impacting recovery performance. To comprehensively
assess and simulate this phenomenon on a larger scale, tests on long-core samples
become essential. However, these tests are never conducted due to the associated time
and costs, along with the requirement for specialized laboratory equipment. As part of
this research program, both single-phase and two-phase core experiments were carried
out on a very long core sample in a responsive reservoir fluid system. These
experiments have yielded crucial insights into how the mixing process influences the
formation of oil and connate water banks. Unlike previous attempts that used shorter
systems, the utilized longer core sample provides a clear understanding of this behavior.
This dataset is of immense value for the practical implementation of low salinity water
injection in the field.
Another challenge stems from the fact that much of the previous research has been done
in i.e. a dead system, where no gas is dissolved in the crude oil sample. This overlooks
the impact of solution gas on the study outcomes. However, this simplification can
potentially introduce alterations in capillary and viscous forces, thereby engendering
uncertainties in findings. In order to assess the impact of both the type and
concentration of dissolved gases on recovery performance and effectively address the
challenge highlighted, core tests were carried out on various systems featuring distinct
solution gases. It's important to note that during these tests, all parameters were kept
constant except for the solution gas variations being investigated. The results indicate
that the presence of CO2 in the associated gas mixture leads to a reduction in the rate of
oil production compared to the dead oil system. Therefore, using dead oil and
overlooking solution gas may introduce uncertainties when planning field applications.
To
Finally, to justify the benefit of low salinity water injection in the field, relative
permeability (kr) functions for both high salinity and low salinity are obtained in a
rservoir fluid system using steady-state core tests. The system has indicated a higher
degree of microdispersion formation and fluid-fluid interactions. In this system, low
salinity water flooding led to a reduction in residual oil saturation (Sor), by 6%, and an
increase in oil relative permeability (kro) values, compared to high salinity water flooding. To identify the role of fluid-fluid interaction on relative permeability (kr)
functions, the oil and water relative permeability curves for both high salinity and low
salinity water injection are obtained using a mineral oil devoid of oil’s polar
compounds. It is pertinent to highlight that, in contrast to the fluid system, other
influential parameters were maintained identical to the reservoir fluid system. This
system showed no change in residual oil saturation (Sor) and and oil relative
permeability (kro) curve when comparing high salinity water flooding with low salinity
water flooding. When comparing the results from the reservoir fluid system and the
mineral oil system, the improvements in kr functions due to low salinity (LS) can be
linked to interactions between crude oil and brine, especially the formation of
microdispersions. Additionally, it's clear that substituting real oil with model oil might
not fully capture the effects of low salinity water, potentially leading to miss out on
opportunities
A multivariate statistical and GIS approach to estimate heavy metal(loid)s in contaminated surface soils
Get PDFIn recent decades, there has been a growing concern over the escalating pollution of soil
with heavy metal(loid)s, which poses an immediate threat to human health, food safety,
and the overall soil environment. This research aimed to assess the extent of
contamination, spatial distribution, sources of contamination, potential ecological risks,
and health hazards associated with heavy metal(loid)s (specifically As, Cd, Co, Cr, Cu,
Fe, Mn, Ni, Pb, Sr, and Zn) by collecting soil samples from the surface soils in the
mining region of Cerrito Blanco and Matehuala, San Luis Potosi in central Mexico. In
addition to this, another study was conducted on rare trace metal(loid)s (B, Ba, Sb, Sn,
and V) and other trace metals (Ca, Mg, Na, and K) in this selected region, which shows
a level of contamination for those metals. The contamination levels of these heavy
metal(loid)s were determined using various indices such as Igeo (geo-accumulation
index), Cf (contamination factor), PLI (pollution load index), Cd (degree of
contamination), mCd (modified degree of contamination), PIN (nemerow pollution
index), EF (enrichment factor), and PERI (potential ecological risk index). Multivariate
statistical techniques, such as principal component analysis (PCA), cluster analysis, or
factor analysis, were used to identification of patterns and correlations among different
heavy metal(loid)s and soil parameters. The findings indicated a significant degree of
contamination in the surface soil due to heavy metal(loid)s. The integrated
contamination indices and the potential ecological risk index revealed high levels of
contamination and substantial ecological risks in the study areas, with particular
emphasis on the need to control As in the surface soils surrounding Matehuala. Source
identification of heavy metal(loid)s were performed using the APCS-MLR, PMF, and
UNMIX receptor models, which detected three potential sources: mining and smelting
activities, natural sources, and anthropogenic activities. The APCS-MLR model
appeared to be more suitable for identifying complex contamination sources,
demonstrating a better R2
coefficient and P/M (predicted/measured) ratio than the other
models. Mining and smelting activities were identified as the primary factors
influencing the distribution of heavy metal(loid)s in the surface soils. The most effective
GIS interpolation technique was selected to analyse the spatial distribution patterns of
heavy metal(loid) content, comparing five different GIS interpolation approaches such
as Inverse Distance Weighting (IDW), Local Polynomial (LP), Ordinary Kriging (OK),
Empirical Bayesian Kriging (EBK), and Radial Basis Functions (RBF). The results
indicated regions of significant concentrations for all heavy metal(loid)s, with the northern, western, and central parts of the study area exhibiting particularly elevated
levels. Ecological risk assessment based on PERI revealed considerable risk for As and
moderate risk for the remaining metals. Moreover, a probabilistic evaluation of health
risks indicated minimal non-carcinogenic risks (HI) for humans but significant
carcinogenic risks (CR) for both adults and children. Notably, children were found to be
more vulnerable to the health risks associated with exposure to these heavy metals
compared to adults. Consequently, enhanced monitoring efforts are necessary to address
the issue of heavy metal(loid)s contamination in the rapidly developing Matehuala
regions.James Watt Scholarshi
An experimental and modelling investigation on the water content of CO2-rich mixtures
Get PDFAs global warming concerns grow, a worldwide appeal for immediate action to reduce greenhouse gas
(GHG) emissions unfold. Many factor such as the emission gap between nations, reliance on petrochemicals
in all industrial sectors, and the difficulty in estimating the carbon footprint in complex and highly specialised
production chains, delay the implementation of practical solutions. In this context, carbon capture, storage
and utilisation (CCSU) emerges as the most readily available option for reducing CO2 emission while promoting a smooth and efficient transition into alternative energy sources. However, transporting and processing
carbon dioxide and CO2-rich mixtures represent a challenging task for many industrial processes. The unavoidable presence of water and the necessity of handling such mixtures over various operational conditions
raises concerns about hydrate formation and corrosion suppression. This study presents an experimental
and modelling investigation for improving field monitoring and model predictions for water content in CO2-
rich mixtures. Measurements are performed using a Tunable Diode Laser Spectroscopy (TDLAS) and a
calibration-free fluid-independent new methodology named Differential Scanning Hygrometry (DSH). This
novel analytical approach has been successfully tested for measuring dew/frost temperatures for carbon
dioxide, methane, nitrogen, CO2-rich mixtures and natural-gas-like synthetic mixtures in equilibrium with
hydrates, free water and ice. In addition, a procedure for dew/frost temperature conversions to mole concentration is also discussed. Further investigations on vapour-liquid CO2/methane and hydrate dissociation for
CO2/propane binary systems are also conducted showing good agreement with recent publications. Finally,
the study has also evaluated the capabilities and limitations of six well-established EoS for modelling natural
gas and CCSU fluids. This evaluation has included the advanced and asymmetric mixing rules (Huron-Vidal,
Orbey-Wong-Sandler and Non-density dependent) coupled with Soave-Redlich-Kwong and Peng-Robinson
EoS, cubic-plus association SAFT hybridisation (CPA) approach and the multiparametric GERG model (a
modified EoS-CG version). A detailed fitting process included tuning saturation pressure for single components, VLE for methane/carbon dioxide, hydrate dissociation, and mutual solubility in binary systems
involving water. Once adjusted, the capabilities of these adjusted models in describing multicomponent mixtures has been assessed. Overall, sCPA and a proposed predictive SRK combined with Huron-Vidal mixing
rules for water-involving binary systems displayed good results with average deviations slightly below 11%
The synthesis and derivation of tetra-substituted methylene bridge calix[4]arenes
Get PDFChapter 1 discusses the history of calix[n]arenes dating back to the initial investigation
of the phenol-formaldehyde procedure up to the seminal work by Gutsche that developed
the synthesis of these macrocycles allowing ease of access. Modification of these
macrocycles is discussed on the upper- and lower-rim followed by a detailed look into
different methods utilised to build functionalisation at the methylene bridge. Finally,
methods of introducing multiple functionalities to the methylene bridge is considered.
Chapter 2 presents the synthesis of a previously reported calix[4]arene which has been
mono-substituted at the methylene bridge containing a saturated 1,4 diketone. This
compound is then used as an intermediate to the synthesis of pyrrole appended C[4]s
through the Paal-Knorr synthesis with a range of different anilines. A library of these
C[4]s is presented with observations and discussions.
Chapter 3 contains a further look into the Paal-Knorr synthesis using the saturated 1,4
diketone intermediate with a set of long chain alkyl-amines. The exploration into other
heterocycles is then discussed including a synthesis of a thiophene using the 1,4 saturated
intermediate and a 1,4 unsaturated diketone with subsequent pyridazine ring closure. The
deprotection of the pyridazine, Thiophene and a long chain alkyl pyrrole is discussed
along with issues encountered, how they are overcome and decomposition of these
compounds.
Chapter 4 discusses introducing pyridyl functionality at the methylene bridge using the
Paal-Knorr synthesis. The different methods considered and trialled followed by
synthesis of two extended anilines and the reaction of 2-,3- and 4-(pyridyl)aniline with
the 1,4 saturated diketone forming the respective pyrroles, the products synthesised and
how these could be used to form asymmetrical calix[4]arenes.
Chapter 5 is a summary and overview of the work presented in this thesis with a small
section on the possible future work in this area
Novel systems and tools for quantum spintronics
Get PDFFor quantum technologies to develop in the future, we need to create and manipulate systems
of increasing complexity. Consequently, a number of challenges must be overcome when
it comes to controlling, calibrating, and validating quantum states and their dynamics.
There is no doubt that a quantum computer will be the only way to simulate large-scale quantum
systems fully; however, classical characterisation and optimisation methods will continue to play
a critical role in the process. In this thesis, we look at one such adaptive method of characterising
the dynamics of a quantum system. We provide theoretical and experimental results on the study
of {T1, T∗2, T2} for a single qubit. We also provide results for the case of multiparameter estimation
and finish the discussion on adaptive estimation with an experiment on frequency estimation via
Ramsey measurement.
Spin-based quantum emitters have shown great promise to be the ideal platforms for quantum applications, particularly quantum networking. However, most of these suffer from large
inhomogeneous broadening and emit outside the telecom band. In the second part of this thesis,
we look at optical, electronic and charge state properties of vanadium (V) defect in SiC with the
goal of its use in quantum networking applications owing to O-band emission and ultra-narrow
inhomogeneous broadening
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