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Modelling solid transport and deposition in urban sewerage systems
Full text linkWith the effects of climate change being felt worldwide the need to conserve water is
essential. Water conservation initiatives promote installation of water efficient and low-flow appliances in wastewater collection systems, resulting in lower flow rates in those
systems than the intended design loading, causing solid deposition and sedimentation in
some areas. An UKWIR/EPSRC CASE grant funded the work described in this Thesis
which investigates sedimentation and solid deposition in building drainage system pipes.
The role of an urban drainage system is to remove waste materials from the habitable
space. Water conservation and sedimentation build up are potential hindrances which
could result in waste materials not leaving the habitable space resulting in increased
sewage spills and posing a hazard to health.
Laboratory and computer modelling investigations were undertaken to determine if an
optimum level of water conservation exists and if this differs from the ‘maximum
achievable’ level of water conservation. Computer simulation output was compared to an
identical full scale laboratory system, with and without sedimentation representing
several months of build-up in a real system. The results indicate that the usage of
additional measures to increase flow energy within an urban sewer system improved solid
transport within the system by a measurable amount. The quantities of water involved
with the additional measures still permit large water savings to be made in the home,
because of the high energy discharge characteristics of the additional measures. The
additional measures included tipping tanks, utilising smaller pipework and standard
volume W.C. cisterns.
It was concluded that the optimal level of water conservation lies between 80% and 60%
of the current levels of water consumption. Lower than 60% results in a lack of solid
transport that is likely to result in operational failure of the sewer system. Mitigating
methodologies have been identified that could allow a further increase in water
conservation while maintaining a functioning sewer system that meets its primary
objective to remove solid waste from inhabited areas.
The work in this thesis demonstrates that consideration needs to be given to the
performance of the sewerage system when considering water conservation methods in
separate systems. With no surface water to provide a flushing mechanism there is a risk
of increased blockages if the flow in the sewerage network is reduced
Responding to climate change through modelling thermal-hydro-mechanical effects on soil behaviour and soil-structure interaction
Full text linkThe stability of the civil infrastructure may be seriously threatened by the variation in soil
behaviour and soil-structure interaction driven by the effects of climate change. Therefore,
geotechnical engineering research continues to be a crucial part of climate change mitigation and
adaptation where it could contribute to new non-structural solutions rather than given the high cost
of new infrastructure and the associated uncertainties.
To deal with the soil-environment interaction problem, the classical soil mechanics formulation
must be progressively generalised in order to incorporate the effects of new phenomena and new
variables on soil behaviour. In this situation, it is essential to understand the thermo-hydro-mechanical behaviour of soils as well as the interaction between soil and structures. This project,
therefore, subjects to developing a comprehensive framework for the study of the thermal-hydro-mechanical behaviour of soil-structure interface and to be able to quantify the change in the
stability of infrastructure under the effect of climate change. In this doctoral research, an extensive
analytical framework will be developed to examine how soils respond to temperature and moisture
changes in critical conditions, with a focus on the thermal-hydro-mechanical response of these
geomaterials. These models were verified and validated with experimental data. Once an
understanding of the potential effects on soils is acquired, the second part of this project will
investigate the effect of temperature and moisture cycles on the soil-structure interaction. The
value of this study is demonstrated by applying it to the analysis of energy piles which experience
simultaneous changes in temperature, water content, and mechanical loads at the soil-pile
interface.
Theoretical advances in thermal-hydro-mechanical behaviour will make it possible to clarify the
mechanisms underlying the interactions between the environment, soil, and structure.
Additionally, the creation of novel models will make it possible to forecast the instability risks
associated with infrastructure projects under the influence of climate change. It is anticipated that
the outcomes of the research will be of relevance to academic audiences and those in the industry.
Success in this project will create a way to properly evaluate geo-environmental uncertainties or
geo-environmentally sensitive projects through better planning and risk mitigation.James-Watt scholarshi
Development of a novel single photon quantum key detection (QKD) optical ground station for secure satellite-based communications
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Thermo-hydro-mechanical behaviour of soils and soil-structure interfaces within the context of climate change
Full text linkThe climate change impacts are undeniable, and since the 1950s, numerous unprecedented
changes have been observed over decades to millennia. Within the bounds of climate change,
fluctuations in soil temperature and water content impose a significant risk on the stability
and serviceability of infrastructures. It is thus necessary to study the thermo-hydro-mechanical (THM) behaviour of soils and soil-structure interfaces, as existing adaptation
strategies suffer from data gaps, and mitigation approaches, such as utilising energy
geostructures, further alter the water content and temperature of the surrounding soil. To
address these issues, an extensive experimental program was carried out, primarily examining
soil-water retention capability at varying temperatures through filter paper tests, soil
volumetric response to cyclic thermal loads through thermal oedometer tests, the shear
response of soil-structure interface in response to THM loads through direct shear tests, and
soil microstructure alteration in response to water content and temperature variation through
scanning electron microscopy (SEM) tests. To facilitate this research, a novel direct shear
setup was also developed to determine the shear behaviour of the interface in response to
THM loads. The findings revealed that the thermal consolidation depends not only on the
overconsolidation ratio () but also on the most recent stress history, occurring only in
fine-grained soils heated beyond the yield temperature, with cooling showing no secondary
thermal consolidation. A clear relationship between thermal volume change and matric
suction was also observed, with higher matric suction resulting in less pronounced particle
rearrangement. Further, SEM analysis revealed that heating beyond the yield temperature
alters the soil microstructure permanently, with cooling showing no impact. In direct shear
tests, the interface friction angle was not significantly affected by matric suction or
temperature, whereas the apparent adhesion increased at all temperatures with matric suction.
Filter paper tests confirmed this phenomenon by revealing a lower water content for the
heated sample at fixed matric suction, which would reduce apparent adhesion. Alternatively,
a temperature decrease or increase led to higher apparent adhesion at all matric suctions
Investigation of machine-learning methods for emerging medical imaging modalities : a case study on fluorescence lifetime and ocular imaging
Full text linkIn recent years, the rise of optical coherence tomography angiography (OCTA), as a
non-invasive modality, has led to a decline in the use of fluorescein angiography. Conversely, fluorescence lifetime imaging (FLIm) has garnered increased attention due to its
ability to differentiate tissue characteristics based on fluorescence signals, particularly
with tumorous tissue. Nevertheless, OCTA is prone to artifacts and diminished image
quality, and FLIm requires other modalities for validation. There is an unmet need for
high-level automatic processing of both modalities, to facilitate their adoption by clinicians and set them as gold standards. Recent advances in deep learning (DL) show
promising results in medical applications. However, medical imaging needs special care,
with an understanding of the underlying conditions, specific metrics with a focus on
positive cases, low computational cost and attention to detail. These aspects are often
secondary in state-of-the-art DL, due to a focus on performance.
This thesis aims to answer the aforementioned challenges by providing comprehensive image analysis alongside classifications and segmentation techniques tailored to
medical imaging.
Firstly, an in-house FLIm dataset of lung tissue with cancer annotations is analysed
and cleaned, accompanied by a study on augmentation techniques. Secondly, we build on
previous published work to improve the classification of cancer on FLIm images leveraging the characteristics of FLIm multi-channel information. Thirdly, fine-grain retinal
imaging segmentation is improved through two methods. The first involves transfer learning from other retinal modalities, exploiting prior knowledge to demonstrate the feasibility of modality- agnostic segmentation. Finally, we study memory usage in DL segmentation and design a new faster neural network with lower memory and computation usage,
without compromising its performance
Planktonic foraminiferal δ13Corg as a novel proxy for past carbon cycling
Full text linkParticulate organic material (POM) in the ocean is a key feature of the biological pump which
plays a crucial role in sequestering carbon from the atmosphere. Variations in the POM carbon
isotopic signal (δ
13Corg-POM) and burial ratio can have a significant impact on the δ13C of
dissolved inorganic carbon. Despite its relevance, our knowledge of the cycling of organic
matter in the past and its isotopic signal is still very limited.
POM analyses can be negatively influenced by several factors such as diagenesis and input of
allochthonous organic carbon. A recent study proposed the isotopic composition of organic
carbon bound to planktonic foraminifera tests (δ13Corg-pforam) as a novel proxy for modern
δ
13Corg-POM, as the organic material sheltered inside the foraminifera test may not be influenced
by similar diagenetic and external processes. The aim of this thesis is to provide insights into
the chemical composition of foraminifera bound organic material (FBOM) and apply it to
assess past δ
13Corg-POM proxy, in relation to different climatic conditions.
In the first results part of this thesis (Chapter 2) a novel combination of gas chromatography-mass spectrometry, flame ionization detection (GC-MS/FID) and liquid chromatography
organic carbon and nitrogen detection (LC-OCD/OND) analyses was used to test for a potential
lipid content inside FBOM. No alkanes, alcohols or fatty acids peaks were detected, and the
results indicate that FBOM is mainly composed of monosaccharides, lower molecular weight
polysaccharides and proteins.
In the second results part (Chapter 3) a δ13Corg-pforam record from the South Atlantic covering
the last 25,000 years is presented and the influence of changing temperature and atmospheric
CO2 is assessed. The obtained results confirm that lower CO2 concentrations during the Last
Glacial Maximum (LGM) resulted in more enriched organic matter δ13C values in this region.
In the fourth chapter of this thesis a new δ13Corg-pforam record from the North Atlantic is
presented, alongside several other Holocene and LGM results from other Atlantic locations.
The aim of this chapter is to assess whether δ
13Corg-pforam records are consistent across the
Atlantic. This chapter results suggest that nutrients availability can influence δ13Corg-pforam by
impacting phytoplankton cell size and growth rate. This finding suggests that although
dissolved CO2 has a significant impact on δ13Corg-pforam, the climatic conditions of the study
area must be taken into consideration
The adoption of risk governance best practices and its impact on bank stability and performance : evidence from Uganda’s commercial banking sector
Full text linkRegulatory implementation of risk governance best practices notwithstanding, the stability of banking
systems, a critical catalyst for economic growth and transformation, continues to be undermined by
bank failures associated with risk governance weaknesses. Does the adoption of risk governance best
practices truly enhance bank stability? In the absence of a universal answer to this question within the
existing literature, this study (or “the study”) seeks to obtain a context-specific answer for small
privately owned banks operating in relatively less sophisticated regulatory environments during a non-crisis period.
The study theoretically integrates agency and institutional frameworks and empirically refers to
published quantitative secondary data from commercial banks in Uganda for the period 2014 - 2023.
Parametric tests and dynamic panel data models are used to test relevant hypotheses. The data reveals
significant variation in the adoption of risk governance best practices between listed and non-listed
banks. However, contrary to hypothesized expectations, risk governance best practices are found to
have no significant impact on bank risk-taking, stability and performance.
The main empirical contribution of the study is new evidence on risk-taking, stability and performance
outcomes of bank risk governance best practices using non-crisis data from small, mostly privately-owned banks operating in a relatively less sophisticated legal and governance context. The integration
of agency and institutional theories also represents an element of methodological advancement,
allowing researchers to better reflect the role of external influences on entity level corporate
governance structures and outcomes.
Implications for practice include highlighting the necessity of taking measures to enhance the
effectiveness of risk governance mechanisms as opposed to simply adopting them which may not
guarantee their impact. Accordingly, the study presents recommendations for stability focussed bank
governance practices, regulation, and supervision
Data-driven discovery of novel lasso peptides with pharmaceutical applications
Full text linkAntimicrobial resistance is a major global health threat and to combat it, there is a need
to discover novel antimicrobials. A promising target for novel drug discovery are lasso
peptides, a class of secondary metabolites with desirable characteristics and sought-after
bioactivities. Here, novel lasso peptides with antimicrobial activity and Streptomyces
origin were sought by using DNA sequencing data to guide experimental procedures.
Initially, it was tested if a high abundance of Actinobacteria and Streptomyces can be used
as an indicator for environments with high potential for secondary metabolism.
Subsequently, metagenomic and bacterial whole genome sequencing data were assessed
for the presence of lasso peptide gene clusters which led to the prediction of 177 potential
lasso peptide gene clusters. Predicted lasso peptide gene clusters were further analysed
for antimicrobial potential, novelty, sequence diversity, and Actinobacterial origin, and
two lasso peptide gene clusters were chosen as cloning targets for further experiments.
One target lasso peptide gene cluster was amplified from eDNA extracted from a volcanic
cave biofilm and subsequently expressed by cell-free biosynthesis and maltose-binding
protein cloning. The antimicrobial potential of the expressed novel lasso peptide was
tested by screening for inhibitory activity against a selection of (multidrug resistant)
ESKAPE pathogens. The results indicated an effect on the growth of Staphylococcus
aureus. In addition to the expression of individual lasso peptide gene clusters,
Streptomyces strains were isolated from environments suggested to be rich in lasso
peptides. A selection of isolates was PCR-screened for lasso peptide genes. Positive PCR
results could be confirmed by Sanger but not by whole genome sequencing
Symmetries and gauge fixing of three dimensional quantum gravity
Full text linkIn this thesis, we study mathematical aspects of three dimensional classical and
quantum gravity. At the classical level we study the Poisson structures of gauge-fixed three dimensional Chern-Simons gravity, fully defined by classical dynamical
r-matrices. We determine all the classical dynamical r-matrices associated to the
Lie algebras of the local isometry groups of three dimensional spacetimes, for both
the Euclidean and Lorentzian signatures and any value of the cosmological constant; highlighting these coindice with the solutions to the Classical Dynamical
Yang-Baxter Equation that appear in the exchange algebra of WZNW models. At
the quantum level we study two quantum group isometries of lorentzian quantum
gravity: the quantum double of SL(2, R) and the quantum k-Poincaré. We prove
these two Hopf algebras are twist-equivalent and examine their semiclassical counterparts
Unpacking service failure across customer journey and performance management within the B2B and B2C business context : an insight from Iran
Full text linkThis thesis draws upon two consolidated theoretical frameworks of attribution blame
theory and process theory. Underpinned by this framework, this study conducts semi-structured interviews with 30 Iranian service providers who are mainly managers or key
marketing staffs and 21 international customers which are categorized into wholesales
(travel agencies’ managers) and retails (individual travellers). The thesis examines and
looks at customer experience (CX) and customer journey (CJ) from a dual vantage point:
that of the customers and the company. It thoughtfully considers all the concurrent
processes involved in the delivery and promotion of services. The findings illustrate that
there are some macro and micro reasons behind service failure and Iranian service
providers seem to have more control over the micro reasons. However, this is not
understandable by the clients and most respondents seemed to ignore the source of failure
and they expected the agency to reassure them that they would handle the problem as
soon as possible. This consumer behaviour contradicts two factors of the attribution
blame theory called stability and controllability and verifies the fact that if failure is
perceived temporary then the customers are prone to forgive and forget.
This thesis discusses the methods Iranian agencies use to check if they are performing
well and if the customers are satisfied. Travel agents seemed to be using different
methods to address these evaluation needs according to the customer phase in their
journey with these inbound agencies. The respondents summarised methods for
controlling and measuring performance and customer satisfaction in three main phases;
evaluation and control before, during (social and technical control)and after the tour
(getting feedback).
This thesis argues how Iranian agencies evaluate their total performance regarding the
tour operation. The findings indicate that most of the service providers seemed to be
happy with their performance. However, they suggested meeting the international
standards and keeping the clients glad is challenging because Iran is a developing country
and lacks good tourism infrastructures. Similarly, most clients seemed satisfied with their
trips to Iran and the services they received. The reason seemed to be not only the services
they received from the agencies but also the destination’s beauty, local people’s
hospitality and low expectation for Iran.
This thesis points out service recovery features and methods that were helpful and made
the customer re-buy the service. Respondents highlighted the importance of choosing a
good tour guide, honesty, reliability, reassurance, accessibility, trust between the parties,
efficiency and speed of recovery journey and clarity and speed of communication as the
prominent features of dealing with an SF. Meanwhile, they believed that apart from these
factors, service providers should not neglect people’s cultural and personality differences
while choosing a proper recovery method. Overall, most participants emphasised the
significant role of the tour guide in making or breaking the tour.Heriot-Watt University scholarshi
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