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Examining the generalization performance of Generative Adversarial Networks in geology
No full textThis thesis investigates the generalization capabilities of Generative Adversarial Networks (GANs) in geology. The main motivation is to utilize the
expressive power of deep generative models to address the challenges in synthesizing realistic and diverse geological realizations particularly when presented with limited training set. The thesis delves into the architecture and
training methodologies of GANs tailored to geology-specific characteristics,
such as geological feature representation within the given samples, spatial
dependencies (e.g., non-stationarity), and large-scale generation. The thesis
first describes how GANs can generate geological channelized patterns with
global proportions beyond a training set that lacks representative samples.
The work modifies the standard conditioning techniques to accommodate for
the missing patterns in the training set. The second work extended the first
method to work in a spatial setting, where it can be trained to generate
non-stationary patterns. It uses a spatial conditioning method and proves
to generate geologically-consistent samples that respect target probability
maps. The final work introduces a novel approach for generating texture
patterns of arbitrary large sizes, including geological samples, given a single
small-resolution image (e.g., 256 × 256). It uses a patch-by-patch generating
technique that efficiently utilizes the GPU resources and is able to generate
coherent large-resolution texture images
Innovation diffusion strategies in the German inpatient healthcare sector using the example of confocal laser endomicroscopy
Get PDFThe German healthcare system is in a constant state of tension between technological
progress and cost consolidation to keep healthcare affordable in a solidarity-based
healthcare system. In cancer treatment – especially malignant brain tumours – rapid
implementation of the latest findings is critical in improving patients’ prognoses.
Although such technology’s clinical value is often evident or at least plausible, its funding
poses a challenge to hospitals and manufacturers because the reimbursement system is
retrospective. German hospital financing regulations hold a limited number of innovation
funding pathways to bridge the time when innovation becomes commercially available to
their integration into the healthcare system. Process cost optimisation along clinical
pathways in terms of reduced total or marginal costs per procedure can demonstrate an
added value and help justify an investment in innovation with missing reimbursements.
The medical device industry needs to understand the healthcare provider’s value chain
within a tight framework of hospital financing legislation to outline innovation
investments’ economic justification and derive effective market development strategies
for innovative products.
The case study elaborates on innovation funding in German hospitals using the example
of confocal laser endomicroscopy (CLE). The convergent mixed methods design provides
qualitative insights into the current challenges hospitals face with innovation funding.
The quantitative research used in this dissertation aims at quantifying the innovation’s
cost-saving potential. Four different market development strategies for the industry are
derived from qualitative and quantitative research synthesis. From these strategic options,
a lighthouse approach is the most promising one because it allows hospitals to build a
strong brand in the market, and the industry can generate a positive cashflow at an early
stage of the technology life cycle. The findings refer to CLE in brain tumour resection
surgery but can be transferred to other technologies for cancer treatment, accelerating
novel treatment methods to reach terminally ill patients
Using species distribution modelling, DNA barcoding and molecular phylogenetics to inform conservation management of Scottish maerl beds
No full textAbstract unavailable. Restricted access until 31.01.2026. Please refer to PDF
Games and interactions to motivate the secure and analytical mindsets of developers
Get PDFToday, poor developer security mindsets, lack of secure programming knowledge, and difficult to use
secure development tools, result in vulnerabilities introduced into code. To resolve these issues, we must
assist developers in improving their practice. We do this by investigating and designing interactions
that motivate developers to be more security conscious as they work. We conduct three different
experiments, evaluating the impact on developer practice.
First, we develop our Citadel Programming Lab to teach secure programming through a serious
game. We find the game, embedded within a lab, is a suitable design to assist and motivate developers
with secure development concepts.
Second, we explore development Issue Prioritisation using security processes. We find that using
security analysis frameworks may be difficult for non-experts and that increased communication is
important.
Third, we evaluate Peer-Testing, a platform supporting students in developing, testing, and reviewing coursework code. We find benefits of peer assessment to program testing, elicits new interactions
between students, and establishes critical analytical review processes.
We find developers desire more help with security and critical evaluation, and over our research we
create and evaluate the value in new interactions which assist and improve developer practice.EPSRC Secrious Project (EP/T017511/1
Optimisation-driven design of energy harvesting systems
No full textThere is a growing interest in the energy available in the environment to enable
the autonomous operation of electronic devices for data transmission. Since vibrations often occur in civil and mechanical systems, they are deemed to be one of the
available sources of energy in a variety of applications. In general, a major motivation behind the energy harvesting (EH) development is to create an application-oriented device, which could recharge a battery powering a solitary sensor or sensor
networks, such as Wireless Sensors Networks (WSNs), and the Internet of Things
(IoT). However, most solutions struggle with low power output and low efficiency.
To date, most of the optimisation efforts in enhancing the performance of energy
harvesters have been focused on the improvement of material properties and on the
establishment of figures of merit to assist in the definition of parameters, neglecting the complex relationship between the device structure, behaviour, and power
output. This thesis fills that gap by developing an optimisation algorithm to establish mechanisms for the optimisation-driven design of energy harvesters. A global
optimisation methodology is developed and applied to improve the performance of
piezoelectric and triboelectric devices, having experimentally validated the analytical and numerical models adopted. A high-power multi-beam piezoelectric energy
harvester is proposed. It utilises a plucking mechanism to excite the beams, organised in a comb-like structure. This thesis proposes solutions to a number of
challenges specific to multi-beam structures that have never been addressed before
and demonstrates that the proposed harvester is able to meet the demands of relevant sensing applications. A high-power output sliding-mode triboelectric energy
harvesting concept is also proposed and its performance is optimised, using the
same methodology. This thesis addresses the limitations of the lateral slide-mode
triboelectric energy harvester and proposes improvements for its design. This is
achieved by overcoming the theoretical limitation of dealing with low unit aspect
ratios, and their consequent edge effect - to date, there is no analytical solution
to account for that factor -, and by the implementation of a global optimisation
process. This work demonstrates the impact that parametric optimisation has on
the performance of the harvester and how limitations imposed on the analytical
models can prevent the analysis in parametric regions where the harvester would
potentially generate more energy
The advertising effects of connected television and digital out of home media : a field experiment
Get PDFTelevision advertising has traditionally been used by marketers to reach mass audiences,
but linear TV viewership is in decline as viewer attention moves toward emerging digital
media. This fragmentation of audiences poses a challenge for marketing practitioners,
who must learn which alternative media should be used in marketing plans to reach
desired consumers. The aim of this research is to provide insights to marketing
practitioners exploring new ways to communicate with fragmented audiences due to
decreased linear TV viewership.
The integrated marketing communications (IMC) paradigm presents one approach to
exploring the individual and combined effects of media activated in an advertising
campaign. However, there is limited information about the advertising effects of
emerging media. As such, connected TV (CTV) and digital out of home (DOOH) have
been selected to test the effectiveness of two emerging media.
A critical literature review develops a conceptual model in accordance with the IMC
paradigm and formulates six hypotheses to test the direct effect of attitude toward media
on attitudinal outcomes of attitude toward the ad and brand opinion, and consumer
decision outcomes of brand awareness, brand consideration, purchase intent and ad recall.
In accordance with a positivist ontology, a field experiment is run for goodr, a nascent
sports sunglasses brand seeking to add media beyond search and social media advertising
to reach new customers. Using a GDPR-compliant mobile-based survey platform, a panel
of 400 consumers is divided into four treatment groups of 100 people each: unexposed,
exposed to CTV only, exposed to DOOH only and exposed to both CTV and DOOH.
Linear and logistic regression analyses are used to assess the correlation between attitude
to media and the dependent variables. Statistically significant positive relationships are
identified for most hypotheses and Hayes Process analyses show statistically significant
indirect relationships with attitude toward the ad as the mediator variable. Despite the
supported hypotheses, the results demonstrate the challenge of measuring IMC activity
given that evidence of media synergies is inconclusive. However, for a new business
seeking to grow market share, the results show CTV and DOOH are effective and should
be considered for media plans. The research provides a foundation for future research by
identifying the need to consider a laboratory element in the methodology and use a video-based DOOH creative treatment to compare the medium with CTV more equally
Protecting the online safety, security and privacy of autistic children and young people
Get PDFThe aim of this PhD thesis was to investigate how autistic children and young people
experience online safety risks and what could help them to navigate such risks in the future. In
Study 1, two groups of parents (autistic children, n = 63; non-autistic children, n = 41)
completed an online survey about their child’s online safety behaviours and wellbeing. Study
2 involved semi-structured interviews with 14 autistic young people aged 11-17 years
investigating their first-hand accounts of their online safety experiences. Study 3 piloted two
low-fidelity prototype solutions to common online safety scenarios with 11 autistic young
people aged 11-18 years, who fed back how these could be improved to help keep themselves
safe in the future.
Results indicated that autistic children experienced significantly more online safety
risks than non-autistic children and poorer wellbeing than autistic children who did not
experience online safety risks.. Secondly, autistic young people reported being victims of
cyberbullying and online sexual harassment and a desire for more design support to block
online comments and/or individuals. Thirdly, autistic young people fed back that visual cues
in low-fidelity prototypes of online safety solutions were beneficial in informing their online
safety risk management.
To conclude, this PhD thesis highlights that autistic children and young people are at
risk pertaining to certain online safety risks. The findings will benefit designers looking to
develop online safety interventions in ways that autistic children will both accept and can
actively benefit from. This research will shape the direction of future interventions and policy
for this population and thus will help to protect autistic children and young people online
Determination and evaluation of the seismic behaviour factor of high-post-yield stiffness concentrically-braced steel frames for improved seismic resilience
Get PDFEurocode-8 aims to protect human life from a design-seismic event and damage
restriction for a frequent seismic event. However, it doesn’t restrict the residual
deformations and doesn’t consider confining the damage accumulation due to possible
aftershocks. Therefore, traditional seismic-resistant frames undergo large residual
deformations that may increase further due to aftershock sequences as the energy is
dissipated through inelastic deformations in the primary framing elements.
This thesis proposes a novel seismic-resistant steel frame that maintains building
functionality after significant earthquakes and subsequent events by reducing the
collapse probability, residual deformations, and damage accumulation while
theoretically eliminating impractical repairs by concentrating the damage in replaceable
elements. The frame has energy-dissipating chevron-type braces equipped with
replaceable hourglass-shaped pins made of duplex stainless steel. Under design seismic
loading, energy is dissipated through inelastic deformations confined in the replaceable
pins while the other framing elements remain elastic. As a result of the inherent
properties of the stainless-steel pins, the frame exhibits high post-yield stiffness, which
reduces the residual drifts. Moreover, the system can hypothetically restore its normal
seismic performance after replacing the damaged pins if the damage is confined in the
pins and residual deformations are kept below the construction tolerance limits.
The seismic performance objectives are set to prevent global collapse under a rare
seismic event and secure human life under a design-seismic action. Furthermore, a
target is established to offer a resilient seismic performance by eliminating the damage
in the framing elements under a design-seismic event. Then, additional damage
limitation objectives are set to limit peak and residual displacements under frequent and
design-level earthquakes, respectively. Last, an objective is set so that the seismic
performance of the frame is not curtailed due to aftershock sequences while limiting the
damage accumulation in the pins.
A novel Eurocode-8-based design methodology is developed for concentrically-braced
systems with high post-yield stiffness and adopted for various archetypes. Then, the
risk-consistent approach recently developed by (Vamvatsikos et al., 2020) (INNOSEIS)
is adopted to determine Eurocode-8-compatible seismic behaviour and overstrength factors. Specifically, the behaviour factor is assessed through fragility analysis based on
incremental dynamic analysis considering high and medium seismicity site-specific
ground motion suites; each matches the seismic hazard at three European sites. In
contrast, the overstrength factor is evaluated through nonlinear pushover analysis.
Furthermore, the recently developed mainshock-consistent-aftershock sequences
selection procedure developed by (Papadopoulos et al., 2020)is integrated with the
INNOSEIS approach in a novel way to evaluate the effects of earthquake sequences
effects on the seismic performance of the frame. Here, the behaviour factor is evaluated
by adopting site hazard-specific sequences selected for a site in Terni, Central Italy,
through damage-dependant fragility analyses based on nonlinear back-to-back dynamic
analyses at multiple intensity levels. Afterwards, prediction models for the damage
accumulation in the pins are developed by linear regression while employing
cumulative energy or duration-based intensity measures. Then, the behaviour factor is
evaluated in terms of damage accumulation using the most reliable prediction model.
Therefore, a detailed numerical nonlinear model is constructed in OpenSees for the
proposed frame integrating experimentally calibrated modelling features. The model
incorporates geometrical and material nonlinearities capturing the strength and stiffness
deterioration of the primary framing members while modelling the fracture of the pin-brace system. The detailed numerical model and the developed design methodology can
be adopted for comparable systems with high post-yield stiffness, conceptually pinned
connections, and possessing symmetric behaviour.
It is validated that the seismic performance of the proposed frame, adopting a behaviour
factor of 6.5 and a design overstrength factor of 3, prevents global collapse and assures
life safety. Also, it ensures concentrating the damage in the pins under a design-seismic
event. Moreover, it guarantees to keep the residual drifts below 1/300 under a design-seismic action and the peak drifts below 0.75% under a frequent seismic event.
However, a reduced behaviour factor of 4 is recommended to keep the residual drifts
below 1/500 and, for archetypes up to 12-storey, the peak drifts below 0.5%. Last, The
performance is validated under mainshock-aftershock sequences for archetypes up to
12-storey, confirming that a behaviour factor of 6.5 guarantees to keep the damage
accumulation index of the pins below 30%, demonstrating the superior fatigue capacity
of the system under earthquake sequences. Here, the cumulative absolute velocity-based
model is adopted as it efficiently predicts the damage accumulation index
The use of offset-dependent time-shifts to characterize dynamic overburden effects in 4D seismic data
No full textTime-lapse seismic surveying is used for the monitoring and management of hydrocarbon
fields in order to evaluate production-related subsurface changes that occur in the reservoir
system. The time-lapse seismic method conventionally analyses 4D attributes of the reservoir
which are generated from stacked versions of the base and monitor datasets which, in turn, are
imaged using a common velocity model. A drawback of this approach is that changes that are
observed in the time-lapse data that occur in the overburden above the reservoir unit may not
be corrected for in the seismic workflow. This lack of update degrades the quality and reliability
of the resultant reservoir time-lapse analysis. This research project investigates the effects of
dynamic changes in the overburden, i.e., variations in conditions in the medium above the
producing reservoir, which occur between the acquisition of the baseline and monitoring survey
datasets. The objective of this research is to evaluate the dynamic overburden effects on the
monitoring programme of the target time-lapse reservoir, to interpret dynamic overburden
effects through the use of 4D time-shift attributes and design methodologies to compensate for
dynamic overburden variations. The focus of this research is the Shearwater field, a high-pressure, high-temperature central North Sea field, which exhibits a common dynamic
overburden system of extensional stress-arching as a reaction to compaction in the Jurassic
reservoir unit.
A synthetic modelling study of a variety of dynamic overburden features shows variability in
the magnitude of time-shift responses as a function of the source-receiver offset at common
midpoint locations beneath the overburden anomalies. These pre-stack, 4D, time-shift
variations are found to be sensitive to the geometry and distribution of the 4D overburden
anomalies, according to the relative exposure of the seismic ray-paths that transect the 4D
effect.
Dynamic overburden effects in the Shearwater field are interpreted via the derivation of pre-stack time attributes of time-shift intercept and time-shift gradient, which are generated via
least-squares fitting of time shifts as a function of offset derived from the base and monitor
datasets. There is agreement between the pre-stack time-shift attributes and the established
overburden extension system. A weak negative gradient of time-shift is noted at the Top Fulmar
reservoir. These attributes are also found to agree with those from an analogue at the South
Arne field, in which a decrease in time-shift is reported from near to far offsets. The
interpretation of the pre-stack, time-shift attributes for the Shearwater field indicates the value
that can be achieved through analysis of pre-stack 4D data, as its use can enable the
characterisation of 4D anisotropy velocity effects and the derivation of geomechanical
attributes such as the stress path parameter.
Two techniques are developed to derive the perturbation velocity from the pre-stack time-shift.
The perturbation velocity is defined as the change in seismic velocity between the base and
monitor surveys. Derivation of the perturbation velocity offers the opportunity to compensate
for dynamic overburden effects that are traditionally ignored in the seismic workflow, via
monitor survey imaging. The first method utilises bi-linear stacking in the offset domain and
relocation of the 4D effect to its implied subsurface location, based on a geometrical
relationship. The application of this method to the Shearwater dataset enables the derivation of
a model that shows alignment to the overburden extensional slow-down and local variations
that coincide with fracture closures in the Hod formation. The second method involves linear
least-squares tomography of pre-stack time-shifts. Application of this technique to Shearwater
leads to the derivation of a model that is aligned with a vertical strain field generated from a
Geertsma model produced from post-stack time-shift data. This project demonstrates the value
of pre-stack inversion in 4D seismic methods and its potential to improve accuracy in 4D
analysis and to deliver information from post-stack analysis that goes beyond conventionally
established workflows
Optical ground receivers for satellite based quantum communications
Get PDFCryptography has always been a key technology in security, privacy and defence.
From ancient Roman times, where messages were sent cyphered with simple encoding techniques, to modern times and the complex security protocols of the Internet.
During the last decades, security of information has been assumed, since classical
computers do not have the power to break the passwords used every day (if they are
generated properly). However, in 1984, a new threat emerged when Peter Shor presented the Shor’s algorithm, an algorithm that could be used in quantum computers
to break many of the secure communication protocols nowadays. Current quantum
computers are still in their early stages, with not enough qubits to perform this
algorithm in reasonable times. However, the threat is present, not future, since the
messages that are being sent by important institutions can be stored, and decoded
in the future once quantum computers are available.
Quantum key distribution (QKD) is one of the solutions proposed for this threat,
and the only one mathematically proven to be secure with no assumptions on the
eavesdropper power. This optical technology has recently gained interest to be performed with satellite communications, the main reason being the relative ease to
deploy a global network in this way. In satellite QKD, the parameter space and
available technology to optimise are very big, so there is still a lot of work to be
done to understand which is the optimal way to exploit this technology.
This dissertation investigates one of these parameters, the encoding scheme.
Most satellite QKD systems use polarisation schemes nowadays. This thesis presents
for the first time an experimental work of a time-bin encoding scheme for free-space
receivers within a full QKD system in the second chapter. The third and fourth
chapter explore the advantages of having multi-protocol free-space receivers that
can boost the interoperability between systems, polarisation filtering techniques to
reduce background. Finally, the last chapter presents a new technology that can
help increase communications rates
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