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Holographic 3D displays
No full text3D displays allow viewers to perceive depth in dynamic images, with applications in
many fields ranging from defence to medical visualisation. However, in comparison
with 2D displays, further development and adoption are hindered by their immatu rity in terms of cost, resolution, and software support .To tackle these challenges,
this thesis aims to develop affordable, high-fidelity 3D displays and related software
applications.
Wavelength multiplexing is realised using diffractive optical elements that exhibit
chromatic dispersion. A compact 3-plane HUD architecture is demonstrated using
an RGB laser projector. A 20-plane volumetric display prototype is developed using
a high-speed projector and a polychromatic light source, displaying 20 volumes per
second.
Two light field display approaches are explored. A patented architecture using
a high-speed projector and spinning mirror(s) is presented, with a 360◦ Field of
View (FOV). A 5.5” flat panel prototype display is also demonstrated, capable of
displaying full-colour 3D images at 60 fps with 49◦ FOV.
The remainder of the work presented is software for visualisation on light field
displays, ranging from showing 3D data in various formats (e.g., medical scans) to
a duplex 3D telepresence application. This work transports 3D displays from novel
hardware to practical, industry-ready solutions.Partly sponsored by the Engineering and Physical
Sciences Research Council (EPSRC
Development of isoform-selective Affimers as novel high affinity agents to study EPAC1 function
Get PDFExchange protein directly activated by cAMP 1 (EPAC1) is an intracellular cyclic AMP
(cAMP) sensor involved in a wide variety of cellular and physiological processes. Despite an
increased understanding of the different roles of EPAC1 in health and disease, reagents are
lacking to study its association with cAMP nanodomains intracellularly. In this work, the non-antibody Affimer protein scaffold was used to develop isoform-selective Affimers of EPAC1.
Phage-display screens against purified, biotinylated human recombinant EPAC1ΔDEP protein
(149-811) identified five potential EPAC1-selective Affimers. Through dot blot and indirect
ELISA assays, Affimer 780A was confirmed to be the top EPAC1-binder. Thermal shift assays
revealed that 780A had a stabilising effect on the EPAC1 protein conformation in vitro and
was found to not discriminate between the active and inactive conformations of EPAC1 in the
presence of the EPAC1-specific agonist 007. HSQC NMR confirmed that the binding of 780A
to the cyclic-nucleotide binding domain (CNBD) of EPAC1 caused a subtle conformational
change. Peptide array technology and mutagenesis studies further revealed a potential
interaction site for 780A in the CNBD. In EPAC1-expressing U2OS cells, 780A was shown to
co-precipitate EPAC1 protein in immunoprecipitation studies. Through fluorescent and
immunofluorescent confocal microscopy, 780A was able to interact with EPAC1 in COS1 cells
and co-localised with both EPAC1 WT and a non-targeting EPAC1-SUMOmutant
predominantly in the perinuclear and cytosolic regions, respectively. As a novel EPAC1-
selective binder, 780A has the potential to be used in super resolution microscopy studies to
further our understanding of the cAMP-EPAC1 signalling pathway
Investigation of the chemical recycling of wool fabrics into a novel fibre for commercial application
Get PDFWool is the most used animal fibre in the fashion industry due to its high quality,
longevity, and wide array of applications in fields ranging from comfortable everyday
apparel to high-performance sports clothing. The value of wool produced via more
environmentally and socially progressive means is increasing, including wool recycled
from post-consumer materials. Wool recycling by mechanical means is compatible with
open- and closed-loop models, but has issues with fibre length, homogeneity, and large
scales; this is in addition to the common issues of any material recycling such as collection
and sorting. An alternative technique is chemical recycling which is currently used for
the treatment of synthetic polymeric materials at various scales. There is hope that this
technique can be adapted to enhance the recycling of wool and may serve complementary
to the current mechanical methods.
This project considers the preliminary chemical recycling of wool keratin to make
textile fibres. Commercial wool offcuts were successfully dissolved by a reduction
process to give solutions of ~ 11.3 weight % (wt%) keratin, showing efficiency of approx.
75.6 %. This keratin solution was blended with 2-hydroethoxy cellulose (HEC) and
polyvinyl alcohol (PVOH), and the resultant blends were used to make films and to create
filaments via a laboratory scale wet-spinning system. The filaments were successfully
cross-linked with glutaraldehyde (GA) and 4,4′-methylenebis- (phenyl isocyanate) (MDI)
to impart useful tensile properties. A variety of filaments were found to have tenacities at
break above 0.5448 cN/Tex (5 g/denier). The tenacities fell within the range of other
fibres on the market, but the extension at break was far below these, suggesting difficulty
in application to the textiles market.
The process was analysed at different stages with Fourier Transform Infrared
spectroscopy (FTIR), Ultraviolet Visible Light spectroscopy (UV-Vis), and SDS
polyacrylamide gel electrophoresis (SDS-PAGE). The surface morphology of the
material was assessed via Scanning Electron Microscopy (SEM) and the tenacity was
tested using Instron apparatus. Although the different stages of the outlined process have
not been optimised due to time constraints, the project serves as a springboard for further
work on lab-scale recovery of wool keratin from waste fabric, specifically for re-use in
the textiles industry
Understanding distribution in homelessness policy : a normative exploration of the differential treatment of homeless households in England, Scotland and Wales
No full textThe social problem of homelessness evokes strong ethical responses but the role of values in this
area has been relatively underexplored. This thesis responds to calls for more normatively engaged
work in homelessness and housing studies by using concepts from distributive justice to explore the
different entitlements of three sub-groups of homeless households (families with children, young
people, and single people) under contemporary homelessness policy in England, Scotland and
Wales. This work aims to improve conceptual clarity regarding normative principles relevant to
homelessness policy, generate empirical evidence of how these principles apply to and interact
within contemporary policy, and develop an evaluative framework through which normative
elements of homelessness policy can be critically assessed.
Underpinned by the critical realist position that ‘invisible’ social phenomena such as normative
perspectives can have a causal impact on empirically identifiable social realities, the thesis draws
upon scholarship from within moral and political philosophy to identify normative grounds for
affording different levels of support or entitlements to different types of homeless household. Six
principles in particular emerge as relevant to different positions in homelessness policy: need,
desert, vulnerability, utility, rights, and equality.
The relationship between these principles and contemporary homelessness policy in England,
Scotland and Wales is explored through primary empirical work, including analysis of key policy
documents and in-depth interviews with thirty-eight key informants. This evidence shows how these
plural values are balanced differently across the three nations, with an emphasis on responding to
acute need in England, a rights-based approach in Scotland, and a distinct split between these
‘selective’ and ‘universal’ positions in Wales. The combination of national homelessness systems and
UK-wide welfare policy produces three distinct household groups: families with children, whose
vulnerability and ‘blamelessness’ underpins strong protections; young people, conceptualised as
vulnerable but offered only ‘patchy’ support; and single adults, historically deprioritised but gaining
increasing policy attention motivated by principles of equality and concern about acute need.
The thesis develops three tools for evaluating the defensibility of these relationships in normative
terms: assessments of internal consistency, theoretical coherence, and reasonableness in the
context of pluralism. Viewing homelessness policy through these different lenses demonstrates how
a normative perspective can uncover sites of conflict, reveal policy areas ripe for change, and
indicate directions of travel that could resolve tensions between principles and practice. In
particular, the thesis highlights a shifting and perhaps diminishing role for the principle of desert in
relation to homelessness and incremental moves towards ‘universalist’ policy in this area.
The work contributes to a growing body of scholarship applying normative ideas to homelessness. It
offers novel strategies for understanding and engaging with normative issues in homelessness policy
and demonstrates how this kind of normative work can aid in mapping the policy landscape, offering
conceptual clarity that supports identification of themes and distinctions between positions. This
forms a strong position from which to evaluate different policy approaches, comparing them against
criteria such as established moral positions or consistency with the policy’s stated aims, and enables
practitioners and policymakers to take account of the moral and social context when determining
future directions
Using small angle neutron scattering (SANS) for a systematic understanding of the pore structure of Mudrocks of different origin
Get PDFTechnologies utilising the subsurface are impacted by the presence and properties of
mudrocks. This includes the petroleum industry evaluating top seals and shale
reservoirs, as well as applications related to the low carbon energy transition plan for a
net zero future: CO2 and energy storage (CH4, H2, and compressed air) and radioactive
waste disposal. To assess the feasibility of mudrocks for technical and geotechnical
applications, the pore structure needs to be characterised in detail. Mudrocks are fine-grained siliciclastic sediments, characterised by complicated textures (size and sorting
of grains) and fabric (arrangement of grains). The pore structure of mudrocks consists of
matrix inter- and intra-particle void space and organic matter intraparticle pores, ranging
from micrometers down to the nanometers in size. With type, size, and organisation of
pores being different, inorganic- and organic-related pore networks lead to the natural
permeability pathways for fluid transport in mudrocks. To quantitatively analyse the
pore structure at a broad pore scale range (~ 2 nm to ~ 5 μm), small angle neutron
scattering (SANS) and low-pressure sorption (LPS) were conducted on 13 sets of
mudrocks originating from radioactive waste storage sites, hydrocarbon seals and shale
gas reservoirs across the globe. These include Opalinus Clay, Switzerland, Boom Clay,
Belgium, Våle Shale, Norway, Posidonia Shale, Germany, Carboniferous Shale,
Belgium, Jordan Oil Shale, Jordan, and Carmel Claystone, Big Hole Carmel, Entrada
Siltstone, Bossier Shale, Haynesville Shale, Eagle Ford Shale, and Newark Shale, USA.
The results have revealed a vast heterogeneity of porosity, which can be related to
the high clay contents and organic matter. Due to the high clay contents and various
types of organic matter, pores smaller than 10 nm constitute a large fraction of the total
porosity (15-50 %) and up to 98 % of the specific surface area. The results indicate that
pore structure varies with a change in the depositional environment. The homogeneous
pore structure of Opalinus Clay reflects a stable, low energy depositional environment.
Boom Clay features variable pore size distribution resulting from variations in grain
sizes due to variable depositional processes. Furthermore, diagenesis and compaction
evolve pore structure of mudrocks during and after sedimentation. The complex
geometry of the pore networks in Carmel stems from dissolution of dolomite by the
geochemical interaction between carbonic acid, resulting in increased macroporosity.
The effective pore structure evolves from the oil to the gas window in organic rich
mudrocks. A progressive amalgamation towards larger pores indicates thermal maturity
and generates secondary organic-matter pores when coarse grained minerals preserve primary porosity. Thermal maturation develops porosity at macroscale range more
effectively, which can enhance the permeability for continuum flow in organic rich
mudrocks.
Based on 71 individual samples, we developed a normal cumulative density function
model to predict porosity as a function of maximum burial depth. The model allows
understanding porosity reduction independent of depositional and post-depositional
processes, like compaction and diagenesis. We further conducted multivariate statistical
analyses consisting of principal component analysis and constrained multilinear
regression to identify and assess the contribution of controls on the pore structure e.g.,
clay content, coarse grained minerals, TOC, and compaction. Principal component
analysis suggests that clay content and compaction are key controls on the pore
structure of organic lean mudrocks. Coarse grained minerals, compaction, and TOC are
key characteristics of organic rich mudrocks. The constrained multilinear regression
shows that the controlling components, compaction and tortuosity, are statistically
significant predictors of the pore structure in all mudrocks. Clay content and coarse-grained minerals have secondary control on porosity. The statistical analyses do not
show a correlation between porosity and TOC content in both oil window and gas
window mudrocks.
Nevertheless, the interplay between mineralogy, organic matter, and compaction
contributes to a pore network of few-to-several nano-Darcy permeability in which pore
size dependent transport mechanisms can vary from transitional transport in micro- and
mesopores to slip flow in meso- and macropores and continuum/Darcy flow in
progressively larger macropores. We developed fractal models to integrate Darcy
permeability with continuum/Darcy flow and apparent permeability and effective
diffusion coefficients with diffusion flow for the relevant pore sizes in mudrocks. The
results indicate that the majority of mudrocks possesses higher apparent permeability
than Darcy permeability that results in a greater total permeability, leading to a better
flow conductivity. On the other hand, the increased macroporosity results in low
diffusivity. To improve fluid dynamic models at pore scale, the incorporation of SANS
PSD, porosity, and SSA as well as pore size dependent fluid flow are necessary to
understand storage capacity and/or transport phenomena more realistically in mudrocks
Coherent light-matter interaction in semiconductor quantum dots
Get PDFCoherent light-matter interaction allows for population control of a single quantum emitter. Detection of the photons emitted immediately after the interaction
is equivalent to reading out the state of the emitter. Frequency and time-domain
measurements on these photons reveal the information about the coherence of the
emitter, typically imprinted as the indistinguishability of the scattered photons.
This thesis focuses on the optical spectroscopy of semiconductor quantum dots at
cryogenic temperature (4 K) under coherent driving. By analyzing the coherence and
the statistics of the scattered photons, the population inversion, the fundamental
dephasing mechanisms, and the coherent coupling amongst emitters can be probed.
First, the experimental data indicates that the coupling of the atom-like transitions to the vibronic transitions of the crystal lattice is independent of the driving
strength, even for detuned excitation using the spin-Λ configuration. This imposes
a fundamental limit to the coherence of the photons emitted from solid-state emitters. Next, the coherent dynamics of a two-level quantum emitter driven by a pair
of symmetrically detuned phase-locked pulses is studied. The spectroscopic results
of a solid-state two-level system show that coherent population control and a large
amount of population inversion are possible using asymmetric dichromatic excitation, which is achieved by adjusting the relative weighting between the red- and blue-detuned pulses. Furthermore, this technique can be extended to multi-level systems
like the biexciton-exciton cascade, such that a pair of suitably detuned laser pulses,
each resonant to the biexciton-exciton or the exciton-ground state transition, can be
used to achieve population inversion from the ground state to the excited (biexciton)
state. In addition, coherent control of cooperative emission arising from two distant
but indistinguishable solid-state emitters due to path erasure is demonstrated via
the results from the photon correlations, measured with Hanbury Brown-Twiss and
Hong-Ou-Mandel interferometers. Finally, applications of these single-photon emitters integrated in deterministically-positioned nanowires and micropillar cavities are
discussed. The former allows for the demonstration of the parallel spectroscopy of
up to 7 emitters using a multi-core-fiber-based confocal microscope. In the latter case, the coherence, indistinguishability as well as photon-number distribution of the
scattered photons from a neutral exciton resonantly coupled to the cavity resonance
are characterized, before they are converted to the telecommunication C-band via
quantum frequency conversion. With these photons, the single-photon BB84 protocol is implemented and a secure key rate of ∼ 1 kHz after propagating through
150 km of optical fiber is observed. This constitutes a key step towards integration
of this single-photon source for fiber-based quantum networking
Tunability and performance enhancement for planar microwave filters
Get PDFRadio-frequency (RF) spectrum is exploited as a valuable resource for wireless
applications such as mobile and satellite communications. As a result, communication
systems including satellite communication and emerging 5G are trending to have
frequency-agility to adapt to highly complex RF environments. However, due to the
nature of materials and components, electrically-tunable planar filters, which play
essential roles in frequency agile RF systems, have their disadvantages of low-order,
high-loss, and poor selectivity. This has limited the overall performances of the
frequency agile RF systems. In the light of this scenario, the objective of this thesis is
to develop efficient performance-enhancement techniques, including the lossy
technique, and the active technique, into the high-selective tunable planar filters to
boost the performances of tunable RF systems.
First of all, an electrically reconfigurable microstrip dual-mode filter is demonstrated
with nonuniform-quality-factor lossy technique. The 4-pole bandpass filter exhibits a
continuously bandwidth tuning and centre frequency tuning capability. By making use
of the doubly tuned resonant property of the dual-mode microstrip open-loop resonator,
passband flatness can be improved by simply loading resistors on the even-odd mode
symmetrical plane of resonators. Moreover, two intrinsic transmission zeros are in
upper and lower stopbands enhancing the filter selectivity. The coupling matrix
synthesis is introduced to describe the nonuniform-quality-factor distribution in a filter
network. The experiment of this type of four-pole tunable lossy filter has presented a
good agreement with the simulation.
Then, the thesis reports a novel 5-pole lossy bandpass filter with the bandwidth
tunability. In order to improve the filter selectivity, we choose a hybrid filter structure
consist of hairpin resonators and dual behaviour resonators to produce two adjustable
transmission zeros for high selective responses. A novel lossy technique named centre-loaded resistive cross-coupling is developed to efficiently reduce the insertion-loss
variation of the tuned passband. The fabricated filter demonstrates an insertion loss
variation of less than 1 dB for all bandwidth states.
To compensate the loss within the varactor-tuned narrowband filter, a tunable 2-pole
active filter is presented with a constant absolute bandwidth. The negative resistance generated from active circuits successfully cancels the loss within the varactor-loaded
resonators resulting in high quality-factor resonator filter responses. With the transistor
small-signal model, the value of the negative resistance of the active circuit can be
predicted by network analysis. Experiments were carried out to validate the design
Extracting business performance signals from Twitter news
Get PDFSocial media and social networks underpin a revolution in communication
between people, with the particular feature that much of that communication is open to
all. This provides a massive pool of data that can be exploited by researchers for a wide
variety of different applications. Data from Twitter is of particular interest in this sense,
given its large global usage levels, and the availability of APIs and other tools that enable
easy access to the publicly available stream of tweets. Owing to the wide public
penetration of Twitter, many businesses make use of it to share their latest news,
effectively using Twitter as a gateway to connect to end-users, consumers and/or
investors.
In this thesis, we focus on the potential for extracting information from Twitter that is
relevant to the financial and competitiveness status of a business. We consider a collection
of well-regarded Twitter accounts that are known for communicating recent business
news, and we investigate the automated analysis of the stream of tweets from these
sources, with a view to learning business-relevant information about specific companies.
A key aspect of our approach is the idea of extracting specific areas of business
performance: we explore three such areas: productivity, competitiveness, and industrial
risk. We propose a two-step model which first classifies a tweet into one of these areas,
and then assigns a sentiment value (on a positive/negative scale). The resulting sentiment
values across specific aspects represent novel business indicators that could add
significant value to the toolset used by business analysts. Our experiments are based on a
new manually pre-classified data set (available from a URL provided).
Additionally, we propose n-grams made from non-contiguous words as a novel feature to
enhance performance in this context. Experiments involving a range of feature selection
methods show that these new features provide valuable benefits in comparison with
standard n-gram features.
We also interduce the concept of an extra layer added to the primary classifier, with the
role of filtering out noisy tweets before they enter the system. We use a One-Class SVM
for this purpose.
Broadly, we show that the methods developed in this thesis achieve promising results in
both topic and sentiment classification in the business performance context, suggesting
that twitter can indeed be a useful source of signals related to different aspects of business performance. We also find that our system can provide valuable insight into unseen test
data. However, more research is needed to be able to extract robust signals for industrial
risk, and there seems to be a considerable promise for further development
Mathematical modelling for red squirrel conservation
Get PDFIn this thesis we develop mathematical models to understand the impact of forest
management and pine marten predation on red and grey squirrel disease-mediated
competitive dynamics. Our work extends a well-tested, spatially-explicit, stochastic
model framework to assess the impact of forest management plans undertaken in
designated red squirrel stronghold forests in Scotland. We determine the impact of
the forest management on the population viability of red squirrels, when threatened
by grey squirrel invasion. The model framework is further extended to identify
natural strongholds - forest sites that act as red squirrel strongholds without the
need for specific forest composition plans or grey squirrel control. The results have
direct implications for forest management practice and will inform an upcoming
review of red squirrel conservation policy on the future of designated strongholds.
The stochastic model framework was modified to include pine marten dynamics
in order to assess the impact of pine marten predation on red and grey squirrel
interactions. Over the last few decades pine marten have seen a recovery in their
density and range in Scotland and Ireland, and this has coincided with a reduction
in grey squirrel density and the recovery of red squirrels. We use the model to
assess the impact of pine marten trans-locations into North Wales, with particular
attention paid to the red squirrels resident on Anglesey and in Clocaenog (a forest
site in North Wales). The thesis also develops a deterministic model framework to
understand how a temporal refuge from predation can mediate the interactions of
competing prey species. This deterministic framework is extended to consider the
red and grey squirrel and pine marten system, where a temporal refuge can occur
when pine marten predation is focussed on the peak phase of vole density cycles.
The refuge from predation has the potential to reverse the beneficial advantage of
pine marten for red squirrels, and provides a necessary note of caution for the role
of pine marten as grey squirrel control agents.
The work in this thesis highlights how important mathematical models are in understanding the potential impact of conservation policy on focal species in Scotland
and Wales.UK Engineering and Physical Sciences Research Council (grant EP/L016508/01
An exploration of female employees' pension engagement as an ecosystem set within a large organisation
Get PDFThis thesis explores female employees’ pension engagement, which is conceptualised as
their active involvement in decision making. This is important because the shift from
final salary towards defined contributions pension products moves responsibility for
decision making and investment risk from employer to employee, while at the same
time while automatic enrolment has led to inertia. Furthermore, women are consistently
reported as less engaged and achieving poorer pension outcomes than men.
Taking an ecosystem perspective, the thesis explores engagement of the individual set
within the meso-level of the Employer and macro-level of pension regulation and
applies the theoretical framework of structure, culture and agency. A case study was
conducted within a large financial services organisation, applying Practice Theory as a
lens to understand pension engagement in the context of workplace marketing practice.
This involved 47 interviews with female employees and those managing the pension,
documentary analysis, observations of meetings, and a communications audit.
The thesis contributes to the theorisation of pension engagement by developing and
modelling an engagement ecosystem which identifies the interaction of structural and
cultural influences across the macro, meso and micro-levels of the ecosystem which
female employees encounter, shaping their pension narratives and influencing variations
in engagement. The employer/employee relationship is identified as critical as the
pension engagement interface encompassing specific affective mechanisms. The thesis
contributes to the marketing discipline by providing an empirically derived model of
engagement; improving understanding of workplace marketing and the influence of the
workplace as a consumption context; and categorising a new system of market practices
for pension engagement. Recommendations are made for policy developments at the
macro-level and for improvements to workplace pension marketing to enable more
female employees achieve better retirement outcomes
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