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Aeroelasticity of a generic wing in ground effect
No full textEmpirical thesis.Bibliography: pages 51-56.1. Introduction -- 2. Literature review -- 3. Methodology -- 4. Results -- 5. Conclusion and future work -- References -- Appendices.The front wing of a Formula car has a significant impact on the overall aerodynamic performance of the vehicle. Previous research proved that the wing proximity to the ground plays a crucial role in the generation of loads and flow structures. However, all previous published research disregarded the effects of wing deformation. This study investigates the aeroelastic behaviour of a downforce producing wing in ground effect by developing and comparing the static loosely-coupled and the tightly-coupled FSI methods. The static loosely-coupled method was incapable of reproducing the loads and deflection oscillations captured by the tightly-coupled FSI, but computed the time-averaged deflection and loadings with discrepancies less than 3% despite using 21 times less computational resources. Further static loosely-coupled FSI simulations were undertaken to analyse the lift loss phenomenon of a flexible wing at two Reynolds numbers. For the Reynolds number of 4.46×105, based on a chord length of 0.223m, the critical height shifted from ́„=0.080̧‘ to ́„=0.091̧‘, whereas it shifted from ́„=0.080̧‘ to ́„=0.101̧‘ for the Reynolds number of 6.69×105. This variation in critical height has been linked to an earlier main wing vortex break down caused by the reduced tip ground clearance due to the deflection.Mode of access: World wide web1 online resource (67 pages) illustrations (some colour
Construction of a cell-free enzymatic pathway for the production of lactic acid from spent coffee grounds
No full textThesis by publication.Includes bibliographic references.Chapter 1. Alternative carbohydrate pathways - enzymes, functions and engineering -- Chapter 2. Characterisation of a mannonate dehydratase from Thermoplasma acidophilum and its potential role in the catabolism of D-mannose -- Chapter 3. Cell-free enzymatic conversion of spent coffee grounds into the platformchemical lactic acid -- Chapter 4. Summary and future perspectives -- Appendices.Microorganisms have been investigated extensively for their use in bio-based production of compounds for the chemical, pharmaceutical and food industry. New tools used in synthetic biology enable a fundamental rewiring of metabolic pathways within microbes. The engineering of cellular metabolisms aims to maximise production efficiencies for the sustainable, yet economically competitive manufacturing of chemicals from renewable biomass. Despite the extensive development in genetic tools, in vivo approaches face challenges such as interference with the host metabolism, restricted flexibility in metabolic design and limited controllability of pathway flux. Alternatively, cell-free biocatalysis has emerged as a promising technology, which is based on an almost unrestricted assembly of enzymes into synthetic and highly modular production pathways. The technology not only offers flexibility to select and combine virtually any enzyme, but also allows for rapid prototyping and testing of de novo assembled pathways. To date, cell-free biocatalysis has been mostly used for the production of chemicals from refined substrates such as glucose and other carbohydrates. Since the economic viability of biotechnological production processes depends heavily on substrate cost, the use of highly abundant and low-cost biomass such as waste products improves the cost-efficiency and the environmental benefit of cell-free biocatalysis.In this work a novel cell-free enzymatic pathway was constructed for the conversion of carbohydrates obtained from spent coffee grounds into lactic acid. Lactic acid is a versatile chemical with a wide range of different applications in medical, textile and food industries and has received most of its attention for the use in form of the biodegradable polymer polylactic acid. Spent coffee grounds are a highly abundant and industrially underutilised waste compound rich in carbohydrates, especially mannose.The catabolism of mannose in most microorganisms relies on the Embden-Meyerhof-Parnas pathway, which is high in enzyme and cofactor cost and therefore suboptimal for a synthetic cell-free approach. The new cell-free pathway described here is based on a non-phosphorylative, putative mannose metabolism from the thermophilic archaeon Thermoplasma acidophilum. Initial identification and characterisation of a thermostable mannonate dehydratase from this organism allowed the construction of a four-enzyme pathway for the conversion of mannose into lactic acid. All the enzymes in the pathway were derived from thermophilic organisms and were recombinantly-expressed, purified and assembled into one-pot reactions. Several reaction conditions (e.g. substrate, cofactor and enzyme concentrations) were studied and optimised towards a conversion yield of up to 71.5 %. In order to demonstrate the feasibility of renewable substrates for cell-free biocatalysis, mannose was obtained by dilute acid hydrolysis from spent coffee grounds and converted into lactic acid using the novel pathway. The conversion from spent coffee grounds into lactic acid was further analysed via high-performance liquid chromatography and showed similar yields as those obtained from pure mannose. Complete identification of reaction intermediates and analysis of pathway flux was possible in reactions containing 13C-labelled substrate via nuclear magnetic resonance spectroscopy. Identification of unspecific side reactions explained the loss of carbon and the conversion below 100% of theoretical yield. Thiswork demonstrates the power of cell-free pathway engineering by construction of an alternative and so far undescribed carbohydrate pathway to convert waste biomass into valuable bio-based chemicals in a sustainable way.Mode of access: World wide web1 online resource (205 pages
The estimation of semiparametric generalized linear models
No full textEmpirical thesis.Bibliography: pages 137-141.1. Introduction -- 2. Literature review -- 3. The semiparametric generalized linear model -- 4. The semiparametric generalized linear model with canonical link -- 5. Application to real data sets -- 6. Conclusions and future work -- Appendix -- References.In this thesis, a novel method for fitting the semiparametric generalized linear model (SPGLM) is developed and tested. We demonstrate that this provides an effective model fitting algorithm to the SP-GLM, particularly, when dealing with very large data sets. We also propose another special SP-GLM and discuss how to fit this special model. This special SP-GLM assumes the canonical link function, which simplifies the algorithm to fit this model.GLMs are widely used for data analysis. However, in some applications, GLMs do not perform well in model fitting when the selected distribution for the response data is inaccurate.The SP-GLM with a nonparametric reference density extends the conventional GLMs. The SP-GLM offers flexibility in regression modelling by relaxing the requirement of a known response distribution in GLMs to only require that the response variable has a distribution from some exponential family. However, a limitation has been observed in the application of the existing SP-GLM method (Huang, 2014) on large data sets, presumably due to the significant increase in the number of constraints for the SP-GLM for large sample sizes. The proposed new SP-GLM methods in this thesis will enable to fit SP-GLM to very large data sets.In this research, the focus is on the regression coefficients estimations and inferences. An iterative algorithm is developed for estimation of the regression coefficients and the reference density simultaneously. The asymptotic properties of the estimators subject to active constraints are also provided.Performance of the proposed methods are tested through simulation studies and real data applications. The simulation results have indicated effectiveness for the methods proposed in this research, with accurate estimation of the regression coefficients, as well as inference. The conclusion reached in this research is that the proposed model fitting methods enhance the capacity of the SP-GLM to handle very large data sets with fast convergence.Mode of access: World wide web1 online resource (xviii, 141 pages) graphs, table
Offloading and content caching in 5G heterogeneous networks: a game-theoretic perspective
No full textEmpirical thesis.Bibliography: pages 171-189.1. Introduction -- 2. Background and related work -- 3. Evolutionary game theory-based offloading in 5G HetNet -- 4. A Nash bargaining game for cooperative content association in 5G HetNet -- 5. Heuristic approach for cache association and bandwidth allocation -- 6. Fair cache association and content placement in 5G HetNet -- 7. Thesis conclusion and future work -- Appendix -- References.The continuous evolution of wireless networks leads to the next generation of wireless network development, dubbed the fifth-generation (5G) mobile wireless network. The forthcoming 5G mobile networks will support diverse mobile data traffic with a one millisecond transmission delay along with reduced energy consumption. In fact every aspect of ongoing 5G research is pointing towards a much better quality-of-service (QoS) provision than its predecessor technology, the currently operating fourth-generation (4G) wireless network. It has been widely claimed that 5G will finally provide the technological edge and the necessary infrastructure to support the so-called internet-of-things (IoT). Thus efficient spectrum usage or spectrum management for 5G is of paramount importance to 5G fruition. While venturing the possibility of accommodating new spectrum seems audacious at this point, it will be the spectrum sharing technologies such as heterogeneous networks (HetNets) at the heart of initial 5G deployment. Het-Nets are becoming increasingly common and rely heavily on the spectrum reuse concept to provide services such as offloading and content-caching. Indeed recent literature puts much emphasis on offloading and content-caching as promising 5G technologies and they will play a vital role in futuristic distributed resource management. Firstly, this thesis focuses on developing a novel offloading approach for 5G dense HetNets. Secondly, this thesis attempts to devise a novel small-cell oriented content-caching approach.The main contribution of this thesis can be summarised in two parts. In the first part, a novel pricing strategy is derived which enforces the low data rate macro users to associate with small-cells. The objective was to increase the spectrum utilisation of small-cells, while preventing cross-tier interference to macro users who are located close to small-cells. Furthermore the proposed pricing algorithm acknowledges one of the shortcomings of the traditional received-signal strength (RSS) based user-association where a user always selects the strongest base station, i.e. the macrocell and thus it becomes overloaded in the process. The pricing algorithm achieves our design objectives as stated above. An evolutionary game-theoretic analysis is provided to show, how the proposed pricing strategy can influence users to select small-cells. Another important aspect of our proposed pricing technique is that a macrocell can control its population share (PS) precisely. By tuning the rate-threshold in the pricing algorithm, a macrocell can have an optimum population share. The evolutionary game captures the essence of the proposed pricing scheme. The mathematical background is provided to show that a unique solution exists. In addition, it is proved that the price-based network selection strategy is evolutionary stable.In the second part, this thesis turns its focus on developing a novel caching strategy that utilises small-cells. Existing caching strategies mainly rely on small cells for caching smaller contents. For retrieving larger contents, existing algorithms either download them from cloud storage or redirect an individual's request to a macrocell. Both approaches result in a higher delay, which motivates us to propose a caching strategy that enures more effcient utilisation of small-cells. The first caching model considers the cache-association strategies of users, which is modelled by a binary decision variable. Unlike existing work, this thesis formulates the small-cell based caching problem into a Nash bargaining game (NBG) and utilises the cooperative nature of an NBG to devise a unique, fair and optima caching strategy. However, the optimisation problem formulation which retains the Nash's axiomatic conditions, turns out to be an integer programming problem. Therefore constraint relaxations are applied to find a centralised solution, which can be used as a lower bound to derive the optimal solution. Afterwards Lagrangian relaxation is used to provide a distributed caching solution. In addition, a low complexity heuristic solution is proposed as an alternative solution to the centralised and distributed solution. By applying the concepts of two-dimensional coordinate geometry it is proved that the bandwidth allocation mechanism of the heuristic algorithm has the same convergence property as Newton's method. Further investigation suggests that the bandwidth allocation mechanism approaches convergence in an iterative manner, therefore it exhibits a much desired property of distributed implementation and parallel computation. This thesis concludes by extending the previously proposed caching model including a cache-placement decision and providing appropriate solution methodology.The new NBG model involves a bilinear term and thus becomes a non-convex integer programming problem. The first step towards solving the problem is to apply a relaxation technique which will convexify the non-convex NBG by relaxing the bilinear term. McCormick relaxation is a well-known method used for convexifying an optimisation model involving bilinear term, which is used in conjunction with Lagrange relaxation to find a feasible solution.Mode of access: World wide web1 online resource (xxvi, 189 pages) diagrams, graph
Impact of MRI technology on Alzheimer's disease detection
No full textTheoretical thesis.Bibliography: pages 54-60.Statement of Originality -- Abstract -- Table of contents -- List of figures -- List of tables -- Acknowledgement -- Alzheimer's Disease Neuroimaging Initiative (ADNI) Acknowledgement -- 1. Introduction -- 2. Background and related works -- 3. AD Diagnostic models -- 4. Data and experimental work -- 5. Result and discussion -- 6. ConclusionAlzheimer's disease (AD) can be detected using magnetic resonance imaging (MRI) based features and supervised classifiers. The subcortical and ventricular volumes change for AD patients. These volumes can be extracted from MRI by tools such as Free Surfer and multi-atlas-based likelihood fusion (MALF) algorithm. Medical imaging centers typically use MRI protocols for brain scanning.These protocol differences include different scanner models with various operating parameters. The scanner models can have the same or different field strengths. A key factor in classifying multicentric MR subject images having different protocols is how different scanner models affect the extraction of features, and subsequent classification performance of a supervised classifier. We have investigated the classification performance of FreeSurfer and MALF based volume features together with Radial Basis Function Support Vector Machine and Extreme Learning Machine across different imaging protocols. We have also investigated both FreeSurfer and MALF, whose defined regions of the brain are most effective for the detection of the disease over different protocols. Our study result indicates marginal differences in classification performance across scanner models with the same or different field strengths when differentiating AD, Mild Cognitive Impairment, and Normal Controls.We have also observed differences in ranking order of the most effective regions.1 online resource (69 pages
Probabilistic models of relational implication
No full textTheoretical thesis.Bibliography: pages 50-51.1. Introduction -- 2. Literature review -- 3. Method -- 4. Experiments -- 5. Conclusion -- A. Appendix: SmallworldKnowledge bases and relational data form a powerful ontological framework for representing world knowledge. Relational data in its most basic form is a static collection of known facts. However, by learning to infer and deduct additional information and structure, we can massively increase the expressibility, generality, and usefulness of the underlying data. One common form of inferential reasoning in knowledge bases is implication discovery. Here, by learning when one relation implies another, we can implicitly extend our knowledge representation. There are several existing models for relational implication, however we argue they are sufficiently motivated but not entirely principled. To this end, we define a formal probabilistic model of relational implication. By using estimators based on the empirical distribution of our dataset, we demonstrate that our model outperforms existing approaches. While previous work achieves a best score of 0 . 7812 AUC on an evaluatory dataset, our ProbE model improves this to 0 . 7915 . Furthermore, we demonstrate that our model can be improved substantially through the use of link prediction models and dense latent representations of the underlying argument and relations. This variant, denoted ProbL, improves the state of the art on our evaluatoin dataset to 0 . 8143 . In addition to developing a new framework and providing novel scores of relational implication, we provide two pragmatic resources to assist future research. First, we motivate and develop an improved crowd framework for constructing labelled datasets of relational implication. Using this, we reannotate and make public a dataset comprised of 17 , 848 instances of labelled relational implication. We demonstrate that precision (as evaluated by expert consensus with the crowd labels) on the resulting dataset improves from 53 % to 95 %. We also argue that current implementations of link prediction models are not sufficiently scalable or parametisable. We provide a highly optimised and parallelised framework for the development and hyperparameter tuning of link prediction models, along with an implementation of a number of existing approaches.1 online resource (ix, 51 pages
An investigation of systemic haemodynamic correlates of intracranial pressure
No full textEmpirical thesis.Bibliography: pages 88-119.Chapter 1. Introduction -- Chapter 2. Literature review -- Chapter 3. Methods -- Chapter 4. Results -- Chapter 5. Discussion -- Chapter 6. Conclusion -- References -- Appendix.Monitoring intracranial pressure (ICP) is vital to decide the appropriate clinical treatment of patients with conditions potentially causing high ICP (e.g. brain injury, cerebral tumor, and hydrocephalus). On the path for finding an alternative means to invasive ICP measurement, the only means to date for accurate ICP monitoring, this study investigates the relationship of ICP with systemic cardiovascular signals ─heart rate (HR), aortic blood pressure (aBP), and carotid blood flow (cBF)─ via rat experiments and signal analysis techniques. Whilst induced changes in aBP and cBF resulted in evident alterations of ICP magnitude, increases of mean ICP up to 49 mmHg showed minimal effect on HR, aBP, or cBF signals. Thus, a stepwise mixed-model regression proved that the cardiovascular parameters here studied have minimal but significant predictive value of ICP magnitude. Changes in HR were found to modify the waveforms observed in ICP, aBP, and cBF signals, without altering the magnitude or phase of transfer function models. The transfer function models were constructed as a function of mean ICP, mean aBP, and aBP or cBF waveforms, and they showed potential to reproduce the ICP waveform (Root Mean Square Error (RMSE)≤4 mmHg), being more accurate for mean aBP above 100 mmHg and mean ICP below 20 mmHg (RMSE≤0.5 mmHg). Likewise, estimation of pulse ICP showed a small error (<1±1.0 mmHg) for mean ICP below 20 mmHg across a range of mean aBP (70-130 mmHg), proving considerable accuracy improvement in relation to previous studies.Mode of access: World wide web1 online resource (120 pages) diagrams, graphs, table
Belief, agency and negative doxastic control
No full textTheoretical thesis.Bibliography: pages 75-78.Chapter 1. Background -- Chapter 2. The empirical defence of involuntarism -- Chapter 3. The conceptual defence of involuntarism -- Chapter 4. Belief, agency and negative doxastic control -- Conclusion -- Bibliography.We commonly refer to the actions performed by an individual, which align with their intentions and goals, as expressions of agency. This is due, at least in part, to that individual’s ability to control what they do. It has become near-orthodoxy however to assert an involuntarist position that we have no, or at least very limited, agential control over our beliefs. Two of the most influential defences of the involuntarist account assert that either beliefs are empirically constrained to be more or less passive responses to our available evidence, or that beliefs are conceptually governed only by considerations of what is true. I argue that both of these defences are problematic because what is apparent in their formulation is an overreliance on investigating the control (or lack thereof) that individuals possess in acquiring beliefs. Subsequently, insufficient attention has centred on the control individuals can exhibit over belief removal. Within this context, I defend the two central claims of this thesis, firstly, that the conclusions reached by the prevailing involuntarist arguments do not sufficiently rule out the conceptual viability of doxastic agency. Secondly, that the concept of Negative Doxastic Control - direct control that we can exhibit over the removal of reasonably held beliefs - in conjunction with many of the precepts of the existing literature can widen the lens of our considerations of doxastic agency, showing ultimately that doxastic agency, properly conceived, is indeed conceptually viable.Mode of access: World wide web1 online resource (vii, 78 pages
The Arrow prayer in the Coptic tradition
No full textTheoretical thesis.Bibliography: pages 253-268.Introduction -- Part One. The status quaestionis and the sources of the arrow prayer. 1. Literature review ; 2. The sources -- Part Two. Antecedents and context. 3. Arrow prayer as weapon of war ; 4. Oral cultures ; 5.Education as a source of formula -- Part Three. Mapping the practice of the arrow prayer. 6. Memorisation ; 7. Meditation ; 8. The Bible as arrow prayer ; 9. The arrow prayer in hagiography -- Conclusion.The New Testament injunction to “pray without ceasing” (1 Thessalonians 5:16-18) was put into practice by early Christians and was further formulated by the Egyptian monks and was eventually known as the Arrow Prayer. The Arrow Prayer was practised by the continuous repetition of a formula, which consists of a bible verse, a saying of a monastic elder, the name of Jesus, or a liturgical formula.From reading key monastic, liturgical and hagiographical sources, we can appreciate the extent of the use of the Arrow Prayer across various social milieus. The aim of this thesis is to provide the social backdrop that explains the widespread use of this prayer, providing evidence from the education system, and the practice of memorisation and meditation in antiquity. I further argue that the Bible was one of the primary sources for the formulas for the Arrow Prayer and for how the practice of this prayer was prominently used to identify the Holy Man in hagiography. By providing the historical context and stipulating the use of the prayer in different milieus, it becomes clear that the Arrow Prayer was in use by monastics and laity in the Coptic Church from the early centuries of Christianity and to an erratic degree the twentieth century.Mode of access: World wide web1 online resource (xvii, 268 pages) table
Coaching parents to implement AAC language systems
No full textThesis by publication.Running title: Coaching parents to implement AAC language systems.Contains bibliographical references.Chapter One. Introduction -- Chapter Two. Parent-implemented symbolic augmentative and alternative communication (AAC) interventions for young children with complex communication needs : a systematic review -- Chapter Three. Coaching parents to implement augmentative and alternative communication (AAC) interventions for young children with complex communication needs -- Chapter Four. Conclusion.This thesis by publication consists of two papers. The first paper is a systematic review of parent-implemented symbolic augmentative and alternative communication (AAC) interventions for young children with complex communication needs. Twenty single case design and three group studies met the selection criteria. Overall, the literature supports the use of parent coaching as effective in supporting parents to implement AAC interventions and parents were able to implement AAC interventions accurately. Aided language interventions were the most effective for supporting ongoing language development. Limitations with the current research and needs for future research are discussed. The second paper is a pilot study, using an AB single case design, investigating the effects of a parent training and coaching aided language stimulation intervention, using a pragmatic organisation dynamic display (PODD) communication system. The study involved two parentchild dyads, (children aged 4.5 years) in a home setting. Dependent variables were parent frequency of AAC symbol use, frequency of speech and use of two language stimulation strategies and children’s symbolic utterances using five-minute samples of parent-child interaction during mealtime and play activities. An effect was demonstrated for both parent and child outcomes. The intervention approach investigated in this pilot study was successful.Mode of access: World wide web1 online resource (ix, 135 pages) graphs, table