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Dissertations / Theses on the topic 'Qa273'

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Published: 25 July 2024
Last updated: 28 July 2024

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1

Chernyavsky, Igor L. "A multiscale analysis of flow and transport in the human placenta." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/13678/.

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The human placenta is characterised by a unique circulatory arrangement, with numerous villous trees containing fetal vessels immersed in maternal blood. Placental tissue therefore manifests a multiscale structure balancing microscopic delivery of nutrients and macroscopic flow. The aims of this study are to examine the interaction between these scales and to understand the influence of placental organisation on the effectiveness of nutrient uptake, which can be compromised in pathologies like pre-eclampsia and diabetes. We first systematically analyse solute transport by a unidirectional flow
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2

Li, Mengdi. "Stochastic modelling and optimization with applications to actuarial models." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12702/.

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This thesis is devoted to Ruin Theory which sometimes referred to the collective ruin theory. In Actuarial Science, one of the most important problems is to determine the finite time or infinite time ruin probability of the risk process in an insurance company. To treat a realistic economic situation, the random interest factor should be taken into account. We first define the model with the interest rate and approximate the ruin probability for the model by the Brownian motion and develop several numerical methods to evaluate the ruin probability. Then we construct several models which incorp
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3

Worby, Colin J. "Statistical inference and modelling for nosocomial infections and the incorporation of whole genome sequence data." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13154/.

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Healthcare-associated infections (HCAIs) remain a problem worldwide, and can cause severe illness and death. The increasing level of antibiotic resistance among bacteria that cause HCAIs limits infection treatment options, and is a major concern. Statistical modelling is a vital tool in developing an understanding of HCAI transmission dynamics. In this thesis, stochastic epidemic models are developed and used with the aim of investigating methicillin-resistant Staphylococcus aureus (MRSA) transmission and intervention measures in hospital wards. A detailed analysis of MRSA transmission and the
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4

Lee, Wai Ha. "Continuous and discrete properties of stochastic processes." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11194/.

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This thesis considers the interplay between the continuous and discrete properties of random stochastic processes. It is shown that the special cases of the one-sided Lévy-stable distributions can be connected to the class of discrete-stable distributions through a doubly-stochastic Poisson transform. This facilitates the creation of a one-sided stable process for which the N-fold statistics can be factorised explicitly. The evolution of the probability density functions is found through a Fokker-Planck style equation which is of the integro-differential type and contains non-local effects whi
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5

Jones, Zofia. "Topics in the mathematical modelling of nanotoxicology." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12436/.

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Over the last ten years questions related to the safety of nanoparticles and their possible toxic effects have become well-established. The government's Health and Safety Laboratories (HSL) at Buxton are currently attempting to determine their possible toxicity in the workplace. It is their responsibility to establish what levels are exposure can be considered safe in the workplace. This project is a CASE studentship with HSL and aims to start developing mathematical models relating to nanotoxicology. After reviewing the available literature, three key mechanisms which are involved in the poss
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6

Verykouki, Eleni. "Stochastic modelling and Bayesian inference for the effect of antimicrobial treatments on transmission and carriage of nosocomial pathogens." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13642/.

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Nosocomial pathogens are usually organisms such as fungi and bacteria that are associated with infections caused in a hospital environment. Examples include Clostridium difficile, Pseudomonas aeruginosa, Vancomycin-resistant enterococcus and Methicillin-resistant Staphylococcus aureus (MRSA). MRSA, like most of the nosocomial pathogens, is resistant to antibiotics and is one of the most serious causes of infections. In this thesis we assess the effects of antibiotics and antiseptics on carriage and transmission of MRSA. We use highly detailed patient level data taken from two Intensive Care Un
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7

Czogiel, Irina. "Statistical inference for molecular shapes." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/12217/.

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This thesis is concerned with developing statistical methods for evaluating and comparing molecular shapes. Techniques from statistical shape analysis serve as a basis for our methods. However, as molecules are fuzzy objects of electron clouds which constantly undergo vibrational motions and conformational changes, these techniques should be modified to be more suitable for the distinctive features of molecular shape. The first part of this thesis is concerned with the continuous nature of molecules. Based on molecular properties which have been measured at the atom positions, a continuous fie
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8

White, Simon Richard. "Stochastic epidemics conditioned on their final outcome." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11274/.

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This thesis investigates the representation of a stochastic epidemic process as a directed random graph; we use this representation to impute the missing information in final size data to make Bayesian statistical inference about the model parameters using MCMC techniques. The directed random graph representation is analysed, in particular its behaviour under the condition that the epidemic has a given final size. This is used to construct efficient updates for MCMC algorithms. The MCMC method is extended to include two-level mixing models and two-type models, with a general framework given fo
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9

Deligiannidis, Georgios. "Some results associated with random walks." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/13104/.

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In this thesis we treat three problems from the theory and applications of random walks. The first question we tackle is from the theory of the optimal stopping of random walks. We solve the infinite-horizon optimal stopping problem for a class of reward functions admitting a representation introduced in Boyarchenko and Levendorskii [1], and obtain closed expressions for the expected reward and optimal stopping time. Our methodology is a generalization of an early paper by Darling et al. [2] and is based on probabilistic techniques: in particular a path decomposition related to the Wiener-Hopf
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10

Knock, Edward Stuart. "Stochastic epidemic models for emerging diseases incorporating household structure and contact tracing." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12046/.

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In this thesis, three stochastic epidemic models for intervention for emerging diseases are considered. The models are variants of real-time, responsive intervention, based upon observing diagnosed cases and targeting intervention towards individuals they have infected or are likely to have infected, be they housemates or named contacts. These models are: (i) a local tracing model for a disease spreading amongst a community of households, wherein intervention (vaccination and/or isolation) is directed towards housemates of diagnosed individuals, (ii) a contact tracing model for a disease sprea
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11

Michelbrink, Daniel. "A Martingale approach to optimal portfolios with jump-diffusions and benchmarks." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12612/.

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We consider various portfolio optimization problems when the stock prices follow jump-diusion processes. In the first part the classical optimal consumption-investment problem is considered. The investor's goal is to maximize utility from consumption and terminal wealth over a finite investment horizon. We present results that modify and extend the duality approach that can be found in Kramkov and Schachermayer (1999). The central result is that the optimal trading strategy and optimal equivalent martingale measure can be determined as a solution to a system of non-linear equations. In another
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12

Mitchell, Mark J. "Mathematical modelling of carbon dioxide dissolution and reaction processes." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/14502/.

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Carbon dioxide dissolution into water is a ubiquitous chemical process on earth, and having a full understanding of this process is becoming ever more important as we seek to understand the consequences of 250 years of exponentially-increasing anthropogenic C02 emissions to the atmosphere since the start of the Industrial Revolution. We examine the dissolution of C02 into water in a number of contexts. First, we analyse what happens to a range of chemical species dissolved in water following an injection of additional C02. We consider the well-mixed problem, and use the method of matched asymp
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13

Ingrey, Philip Charles. "Optical limits in Left-Handed Media." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11392/.

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This thesis determines the response of Left-Handed Media (LHM) to surface effects. A LHM half-space with a roughened interface, modelled by a graded index boundary, is shown to give rise to an analytical solution for the propagation of electromagnetic radiation through this inhomogeneous layer. Significant field localization is generated within the layer, caused by the coherent superposition of evanescent waves. The localization is shown to greatly deteriorate transmission when losses are present. The addition of a second interface to the LHM, creating a perfect lens configuration, allows for
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14

Stone, Nicola. "Gaussian process emulators for uncertainty analysis in groundwater flow." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11989/.

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In the field of underground radioactive waste disposal, complex computer models are used to describe the flow of groundwater through rocks. An important property in this context is transmissivity, the ability of the groundwater to pass through rocks, and the transmissivity field can be represented by a stochastic model. The stochastic model is included in complex computer models which determine the travel time for radionuclides released at one point to reach another. As well as the uncertainty due to the stochastic model, there may also be uncertainties in the inputs of these models. In order
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15

Ball, Sue. "Stochastic models of ion channels." Thesis, University of Nottingham, 2001. http://eprints.nottingham.ac.uk/11277/.

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This thesis is concerned with models and inference for single ion channels. Molecular modelling studies are used as the basis for biologically realistic, large state-space gating models of the nicotinic acetylcholine receptor which enable single-channel kinetic behaviour to be characterized in terms of a small number of free parameters. A model is formulated which incorporates known structural information concerning pentameric subunit composition, interactions between neighbouring subunits and knowledge of the behaviour of agonist binding sites within the receptor-channel proteins. Expressions
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16

Shortland, Christopher Francis. "Some results on boundary hitting times for one-dimensional diffusion processes." Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/11465/.

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Boundary hitting times for one-dimensional diffusion processes have applications in a variety of areas of mathematics. Unfortunately, for most choices of diffusions and boundaries, the exact exit distribution is unknown, and an approximation has to be made. The primary requirements of an approximation, from a practical viewpoint, is that it is both accurate and easily computable. The main, currently used approximations are discussed, and a new method is developed for two-sided boundaries, where current methodology provides very few techniques. In order to produce new approximations, we will ma
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17

Fayomi, Aisha Fouad. "Robust versions of classical multivariate techniques based on the Cauchy likelihood." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13446/.

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Classical multivariate analysis techniques such as principal components analysis (PCA), canonical correlation analysis (CCA) and discriminant analysis (DA) can be badly affected when extreme outliers are present. The purpose of this thesis is to present new robust versions of these methods. Our approach is based on the following observation: the classical approaches to PCA, CCA and DA can all be interpreted as operations on a Gaussian likelihood function. Consequently, PCA, CCA and DA can be robustified by replacing the Gaussian likelihood with a Cauchy likelihood. The performance of the Cauch
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18

Baaqeel, Hanan. "Central limit theorems and statistical inference for some random graph models." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29294/.

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Random graphs and networks are of great importance in any fields including mathematics, computer science, statistics, biology and sociology. This research aims to develop statistical theory and methods of statistical inference for random graphs in novel directions. A major strand of the research is the development of conditional goodness-of-fit tests for random graph models and for random block graph models. On the theoretical side, this entails proving a new conditional central limit theorem for a certain graph statistics, which are closely related to the number of two-stars and the number of
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19

Wilson, Lorna Rachel Maven. "The impact of periodicity on the zero-crossings of random functions." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/30472/.

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Continuous random processes are used to model a huge variety of real world phenomena. In particular, the zero-crossings of such processes find application in modelling processes of diffusion, meteorology, genetics, finance and applied probability. Understanding the zero-crossings behaviour improves prediction of phenomena initiated by a threshold crossing, as well as extremal problems where the turning points of the process are of interest. To identify the Probability Density Function (PDF) for the times between successive zero-crossings of a stochastic process is a challenging problem with a
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20

Cao, Yufei. "Zero-crossing intervals of Gaussian and symmetric stable processes." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39997/.

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The zero-crossing problem is the determination of the probability density function of the intervals between the successive axis crossings of a stochastic process. This thesis studies the properties of the zero-crossings of stationary processes belonging to the symmetric-stable class of Gaussian and non-Gaussian type, corresponding to the stability index nu=2 and 0 < nu < 2 respectively.
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21

Foulger, Iain. "Quantum walks and quantum search on graphene lattices." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27717/.

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This thesis details research I have carried out in the field of quantum walks, which are the quantum analogue of classical random walks. Quantum walks have been shown to offer a significant speed-up compared to classical random walks for certain tasks and for this reason there has been considerable interest in their use in algorithmic settings, as well as in experimental demonstrations of such phenomena. One of the most interesting developments in quantum walk research is their application to spatial searches, where one searches for a particular site of some network or lattice structure. There
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22

Davis, Ben. "Stochastic epidemic models on random networks : casual contacts, clustering and vaccination." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/47272/.

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There has been considerable recent interest in models for epidemics on networks describing social contacts. This thesis considers a stochastic SIR (Susceptible - Infective - Removed) model for the spread of an epidemic among a population of individuals, with a random network of social contacts, that is partitioned into households and in which individuals also make casual contacts, i.e. with people chosen uniformly at random from the population. The behaviour of the model as the population tends to infinity is investigated. A threshold parameter that governs whether or not the epidemic with an
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23

Pérez, López Iker. "Results in stochastic control : optimal prediction problems and Markov decision processes." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28395/.

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The following thesis is divided in two main topics. The first part studies variations of optimal prediction problems introduced in Shiryaev, Zhou and Xu (2008) and Du Toit and Peskir (2009) to a randomized terminal-time set up and different families of utility measures. The work presents optimal stopping rules that apply under different criteria, introduces a numerical technique to build approximations of stopping boundaries for fixed terminal time problems and suggest previously reported stopping rules extend to certain generalizations of measures. The second part of the thesis is concerned w
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24

Tilūnaitė, Agnė. "Modelling of intracellular calcium dynamics." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/48909/.

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Ca2+ as a universal messenger participates in a great variety of physiological functions and biological events such as cell maturation, chemotaxis or gene expression. These diverse functions are controlled through complex spatio-temporal calcium patterns. To date it is known that these patterns depend on stimuli type and concentration. However, the majority of these observations were from constant or step change stimulation protocols. Under these conditions two leading hypotheses for the stimulus encoding into cytosolic calcium responses were proposed, namely amplitude and frequency modulation
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25

Dinh, Jean-Louis T. Q. "Mathematical modelling of the floral transition." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/45106/.

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The floral transition is a developmental process through which some plants commit to flowering and stop producing leaves. This is controlled by changes in gene expression in the shoot apical meristem (SAM). Many of the genes involved are known, but their interactions are usually only studied one by one, or in small sets. While it might be necessary to properly ascertain the existence of regulatory interactions from a biological standpoint, it cannot really provide insight in the functioning of the floral-transition process as a whole. For this reason, a modelling approach has been used to inte
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26

Gao, Yu. "Statistical modelling of games." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33298/.

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This thesis mainly focuses on the statistical modelling of a selection of games, namely, the minority game, the urn model and the Hawk-Dove game. Chapters 1 and 2 give a brief introduction and survey of the field. In Chapter 3, the key characteristics of the minority game are reproduced. In addition, the minority game is extended to include wealth distribution and leverage effect. By assuming that each player has initial wealth which rises and falls according to profit and loss, with the potential of borrowing and bankruptcy, we find that modelled wealth distribution may be power law distribut
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27

Wicks, Thomas J. "Molecular simulation of nucleation in polymers." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32012/.

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We develop several new algorithms using molecular simulation to investigate the nucleation barrier of a single, freely-jointed polymer chain. In the first part of the thesis, we use a free particle model to develop a new biasing technique, which uses an automated feedback mechanism to overcome the poor sampling of crystal states in a thermodynamic system. Our feedback technique does not require any prior knowledge of the nucleation barrier and enables good representative sampling of all available states of interest. In the second part of the thesis, we simulate the nucleation barrier of the si
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28

Duduială, Ciprian Ionut. "Stochastic nonlinear models of DNA breathing at a defect." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11027/.

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Deoxyribonucleic acid (DNA) is a long polymer consisting of two chains of bases, in which the genetic information is stored. A base from one chain has a corresponding base on the other chain which together form a so-called base-pair. Molecular-dynamics simulations of a normal DNA duplex show that breathing events – the temporary opening of one or more base-pairs – typically occur on the microsecond time-scale. Using the molecular dynamics package AMBER, we analyse, for different twist angles in the range 30-40 degrees of twist, a 12 basepair DNA duplex solvated in a water box, which contains t
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29

Blackwell, Paul Gavin. "The stochastic modelling of social and territorial behaviour." Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/13594/.

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This thesis considers mathematical models of the interaction between social and territorial behaviour in animals, mainly by probabilistic methods. Chapter 1 introduces the Resource Dispersion Hypothesis, which suggests that territorial behaviour plus dispersed food resources can explain the existence of social groups, and describes an existing model of the process, due to Carr and Macdonald. In Chapter 2 the model of Carr and Macdonald is analysed, and in Chapter 3 an improved model is suggested and its main properties derived, primarily using renewal theory. Chapters 4 and 5 consider various
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30

Spencer, Simon. "Stochastic epidemic models for emerging diseases." Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/11132/.

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In this thesis several problems concerning the stochastic modelling of emerging infections are considered. Mathematical modelling is often the only available method of predicting the extent of an emerging disease and assessing proposed control measures, as there may be little or no available data on previous outbreaks. Only stochastic models capture the inherent randomness in disease transmission observed in real-life outbreaks, which can strongly influence the outcome of an emerging epidemic because case numbers will initially be small compared with the population size. Chapter 2 considers a
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31

Shaw, Laurence M. "SIR epidemics in a population of households." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/38606/.

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The severity of the outbreak of an infectious disease is highly dependent upon the structure of the population through which it spreads. This thesis considers the stochastic SIR (susceptible → infective → removed) household epidemic model, in which individuals mix with other individuals in their household at a far higher rate than with any other member of the population. This model gives a more realistic view of dynamics for the transmission of many diseases than the traditional model, in which all individuals in a population mix homogeneously, but retains mathematical tractability, allowing u
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32

Dunster, Joanne L. "Mathematical models of soft tissue injury repair : towards understanding musculoskeletal disorders." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/27797/.

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The process of soft tissue injury repair at the cellular lew I can be decomposed into three phases: acute inflammation including coagulation, proliferation and remodelling. While the later phases are well understood the early phase is less so. We produce a series of new mathematical models for the early phases coagulation and inflammation. The models produced are relevant not only to soft tissue injury repair but also to the many disease states in which coagulation and inflammation play a role. The coagulation cascade and the subsequent formation of the enzyme thrombin are central to the creat
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33

van, Horssen Merlijn. "Large deviations and dynamical phase transitions for quantum Markov processes." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27741/.

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Quantum Markov processes are widely used models of the dynamics open quantum systems, a fundamental topic in theoretical and mathematical physics with important applications in experimental realisations of quantum systems such as ultracold atomic gases and new quantum information technologies such as quantum metrology and quantum control. In this thesis we present a mathematical framework which effectively characterises dynamical phase transitions in quantum Markov processes, using the theory of large deviations, by combining insights developed in non-equilibrium dynamics with techniques from
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34

Davies, Jonathan. "Sparse regression methods with measurement-error for magnetoencephalography." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/48062/.

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Magnetoencephalography (MEG) is a neuroimaging method for mapping brain activity based on magnetic field recordings. The inverse problem associated with MEG is severely ill-posed and is complicated by the presence of high collinearity in the forward (leadfield) matrix. This means that accurate source localisation can be challenging. The most commonly used methods for solving the MEG problem do not employ sparsity to help reduce the dimensions of the problem. In this thesis we review a number of the sparse regression methods that are widely used in statistics, as well as some more recent method
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Sajib, Anamul. "A Bayesian model for the unlabelled size-and-shape analysis." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/55511/.

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This thesis considers the development of efficient MCMC sampling methods for Bayesian models used for the pairwise alignment of two unlabelled configurations. We introduce ideas from differential geometry along with other recent developments in unlabelled shape analysis as a means of creating novel and more efficient MCMC sampling methods for such models. For example, we have improved the performance of the sampler for the model of Green and Mardia (2006) by sampling rotation, A ∈ SO(3), and matching matrix using geodesic Monte Carlo (MCMC defined on manifold) and Forbes and Lauritzen (2014) m
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Howitt, Ryan. "Stochastic modelling of repeat-mediated phase variation in Campylobacter jejuni." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52218/.

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It is of interest to determine how populations of bacteria whose genes exhibit an ON/OFF switching property (phase variation) evolve over time from an initial population. By statistical analysis of two in vitro experimental Campylobacter jejuni datasets containing 28 genes assumed to be phase variable, we find evidence of small networks of genes which exhibit dependent evolutionary behaviour. This violates the assumption that the genes in these datasets do not interact with one another in the way they mutate during the division of cells, motivating the development of a model which attempts to
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37

Alharthi, Muteb. "Bayesian model assessment for stochastic epidemic models." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33182/.

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Acrucial practical advantage of infectious diseases modelling as a public health tool lies in its application to evaluate various disease-control policies. However, such evaluation is of limited use, unless a sufficiently accurate epidemic model is applied. If the model provides an adequate fit, it is possible to interpret parameter estimates, compare disease epidemics and implement control procedures. Methods to assess and compare stochastic epidemic models in a Bayesian framework are not well-established, particularly in epidemic settings with missing data. In this thesis, we develop novel m
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Haque, Mainul. "Mathematical modelling of eukaryotic stress-response gene networks." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12509/.

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Mathematical modelling of gene regulatory networks is a relatively new area which is playing an important role in theoretical and experimental investigations that seek to open the door to understanding the real mechanisms that take place in living systems. The current thesis concentrates on studying the animal stress-response gene regulatory network by seeking to predict the consequence of environmental hazards caused by chemical mixtures (typical of industrial pollution). Organisms exposed to pollutants display multiple defensive stress responses, which together constitute an interlinked gene
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March, Jack. "Determining the location of an impact site from bloodstain spatter patterns : computer-based analysis of estimate uncertainty." Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/10166/.

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The estimation of the location in which an impact event took place from its resultant impact spatter bloodstain pattern can be a significant investigative issue in the reconstruction of a crime scene. The bloodstain pattern analysis methods through which an estimate is constructed utilise the established bloodstain pattern analysis principles of spatter bloodstain directionality, impact angle calculation, and straight-line trajectory approximation. Uncertainty, however, can be shown to be present in the theoretical definition and practical approximation of an impact site; the theoretical justi
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Hall, Fenella T. H. "Mathematical models for class-D amplifiers." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11891/.

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We here analyse a number of class-D amplifier topologies. Class-D amplifiers operate by converting an audio input signal into a high-frequency square wave output, whose lower-frequency components can accurately reproduce the input. Their high power efficiency and potential for low distortion makes them suitable for use in a wide variety of electronic devices. By calculating the outputs from a classical class-D design implementing different sampling schemes we demonstrate that a more recent method, called the Fourier transform/Poisson resummation method, has many advantages over the double Four
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41

Milne, Andrew. "Topics in flow in fractured media." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11957/.

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Many geological formations consist of crystalline rocks that have very low matrix permeability but allow flow through an interconnected network of fractures. Understanding the flow of groundwater through such rocks is important in considering disposal of radioactive waste in underground repositories. A specific area of interest is the conditioning of fracture transmissivities on measured values of pressure in these formations. This is the process where the values of fracture transmissivities in a model are adjusted to obtain a good fit of the calculated pressures to measured pressure values. W
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42

Stephens, David A. "Bayesian edge-detection in image processing." Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/11723/.

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Problems associated with the processing and statistical analysis of image data are the subject of much current interest, and many sophisticated techniques for extracting semantic content from degraded or corrupted images have been developed. However, such techniques often require considerable computational resources, and thus are, in certain applications, inappropriate. The detection localised discontinuities, or edges, in the image can be regarded as a pre-processing operation in relation to these sophisticated techniques which, if implemented efficiently and successfully, can provide a means
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43

Amaral, Getulio J. A. "Bootstrap and empirical likelihood methods in statistical shape analysis." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/11399/.

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The aim of this thesis is to propose bootstrap and empirical likelihood confidence regions and hypothesis tests for use in statistical shape analysis. Bootstrap and empirical likelihood methods have some advantages when compared to conventional methods. In particular, they are nonparametric methods and so it is not necessary to choose a family of distribution for building confidence regions or testing hypotheses. There has been very little work on bootstrap and empirical likelihood methods in statistical shape analysis. Only one paper (Bhattacharya and Patrangenaru, 2003) has considered bootst
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Demiris, Nikolaos. "Bayesian inference for stochastic epidemic models using Markov chain Monte Carlo methods." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/10078/.

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This thesis is concerned with statistical methodology for the analysis of stochastic SIR (Susceptible->Infective->Removed) epidemic models. We adopt the Bayesian paradigm and we develop suitably tailored Markov chain Monte Carlo (MCMC) algorithms. The focus is on methods that are easy to generalise in order to accomodate epidemic models with complex population structures. Additionally, the models are general enough to be applicable to a wide range of infectious diseases. We introduce the stochastic epidemic models of interest and the MCMC methods we shall use and we review existing methods of
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45

Christen, José Andrés. "Bayesian interpretation of radiocarbon results." Thesis, University of Nottingham, 1994. http://eprints.nottingham.ac.uk/11035/.

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Over the last thirty years radiocarbon dating has been widely used in archaeology and related fields to address a wide-range of chronological questions. Because of some inherent stochastic factors of a complex nature, radiocarbon dating presents a rich source of challenging statistical problems. The chronological questions posed commonly involve the interpretation of groups of radiocarbon determinations and often substantial amounts of a priori information are available. The statistical techniques used up to very recently could only deal with the analysis of one determination at a time, and no
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46

Polson, Nicholas G. "Bayesian perspectives on statistical modelling." Thesis, University of Nottingham, 1988. http://eprints.nottingham.ac.uk/11292/.

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This thesis explores the representation of probability measures in a coherent Bayesian modelling framework, together with the ensuing characterisation properties of posterior functionals. First, a decision theoretic approach is adopted to provide a unified modelling criterion applicable to assessing prior-likelihood combinations, design matrices, model dimensionality and choice of sample size. The utility structure and associated Bayes risk induces a distance measure, introducing concepts from differential geometry to aid in the interpretation of modelling characteristics. Secondly, analytical
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Lee, T. D. "Implementation of the Bayesian paradigm for highly parameterised linear models." Thesis, University of Nottingham, 1986. http://eprints.nottingham.ac.uk/14421/.

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This thesis re-examines the Bayes hierarchical linear model and the associated issue of variance component estimation in the light of new numerical procedures, and demonstrates that the Bayes linear model is indeed a practical proposition. Technical issues considered include the development of analytical procedures essential for efficient evaluation of the likelihood function, and a partial characterisation of the difficulty of likelihood evaluation. A general non-informative prior distribution for the hierarchical linear model is developed. Extensions to spherically symmetric error distributi
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48

Xu, Xiaoguang. "Bayesian nonparametric inference for stochastic epidemic models." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29170/.

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Modelling of infectious diseases is a topic of great importance. Despite the enormous attention given to the development of methods for efficient parameter estimation, there has been relatively little activity in the area of nonparametric inference for epidemics. In this thesis, we develop new methodology which enables nonparametric estimation of the parameters which govern transmission within a Bayesian framework. Many standard modelling and data analysis methods use underlying assumptions (e.g. concerning the rate at which new cases of disease will occur) which are rarely challenged or teste
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Yu, Chen. "The use of mixture models in capture-recapture." Thesis, University of Kent, 2015. https://kar.kent.ac.uk/50775/.

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Mixture models have been widely used to model heterogeneity. In this thesis, we focus on the use of mixture models in capture--recapture, for both closed populations and open populations. We provide both practical and theoretical investigations. A new model is proposed for closed populations and the practical difficulties of model fitting for mixture models are demonstrated for open populations. As the number of model parameters can increase with the number of mixture components, whether we can estimate all of the parameters using the method of maximum likelihood is an important issue. We expl
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Hubbard, Ben Arthur. "Parameter redundancy with applications in statistical ecology." Thesis, University of Kent, 2014. https://kar.kent.ac.uk/47436/.

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This thesis is concerned with parameter redundancy in statistical ecology models. If it is not possible to estimate all the parameters, a model is termed parameter redundant. Parameter redundancy commonly occurs when parameters are confounded in the model so that the model could be reparameterised in terms of a smaller number of parameters. In principle, it is possible to use symbolic algebra to determine whether or not all the parameters of a certain ecological model can be estimated using classical methods of statistical inference. We examine a variety of different ecological models: We begi
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