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Barr, Gordon. "A probabilistic risk modelling methodology for the formative stages of engineering projects." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402343.
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Webb, Mary E. "The design and formative evaluation of computer based qualitative modelling environments for schools." Thesis, Open University, 1995. http://oro.open.ac.uk/57609/.
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This research investigated how computers might enable young learners to build models so that they can express and explore their ideas and hence they can gain understanding of the subject matter as well as developing modelling abilities. A design for a qualitative modelling environment was produced, which incorporated a simple rule-based metaphor that could be presented as a diagram. The design was founded on empirical evidence of children modelling as well as theoretical grounds. This research originated in and contributed to the Modus Project, a joint venture between King's College London and the Advisory Unit for Microtechnology in Education, Hertfordshire County Council. A prototype of the software, Expert Builder, was implemented by software engineers from the Modus team. The initial stage of evaluation, based on a questionnaire survey and widespread trialling, established that the tool could be used in a wide range of educational contexts. A detailed study of children using the qualitative modelling environment was conducted in three primary schools involving 34 pupils, aged nine to 11. They used the modelling environment within the classroom in their normal curriculum work over one school year on a variety of topics assisted by their class teacher. The modelling environment enabled cooperative groupwork and supported pupils in consolidating and extending their knowledge. A formative evaluation was used to inform the design of a revised version of the software. In addition the experiences of children using the software were analysed. A framework was developed which characterised the stages in the modelling process. Teachers in the study were observed to demonstrate the earlier stages of the modelling process and then to set tasks for the children based on the later stages of building and testing the models. The evidence suggested that the abilities to model were context dependent so that pupils as young as nine years old could undertake the whole modelling process provided that they were working on subject matter with which they were familiar. The teachers made use of computer based modelling in order to develop and reinforce pupils' understanding of various aspects of the curriculum and therefore they chose modelling tasks for the children. However in one school the children were given the opportunity to design and build models of their own choice and they demonstrated that they were able to carry out all the stages in the modelling process. A taxonomy of computer based modelling is proposed which could be used to inform decisions about the design of the modelling curriculum and could provide a basis for researchers investigating the modelling process. This would be useful for further research into the intellectual and social activities of people learning to model and for teachers seeking to develop a framework for the modelling curriculum. The National Curriculum (Department of Education and Science and the Welsh Office, 1990) specifies that early steps in computer based modelling should involve exploring models developed by others and pupils are not required to build models themselves until level 7 which is expected to be reached by more able 14 year-olds. In this thesis it is argued that a modelling curriculum should provide early opportunities for pupils to undertake the modelling process by developing simple models on familiar subject matter as well as opportunities for exploring more complex models as evidence from research reported in this thesis suggests that younger pupils are able to build models. In this way pupils will be enabled to acquire modelling capability as well as developing their understanding of a range of topics through modelling. Progression in modelling capability would involve constructing models of more complex situations and using a wider range of modelling environments.
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Patel, Brijesh. "Performance and the National Health Service : modelling for formative policy evaluation and strategic planning." Thesis, University of Westminster, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441078.
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Grace, Tim, and n/a. "An investigation of primary school children's clay modelling techniques." University of Canberra. Education, 1993. http://erl.canberra.edu.au./public/adt-AUC20060712.130505.
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Children in their final years of primary schooling tend to emphasize the
use of detail and the production of naturalistic representations, when
modelling the human figure with clay. Children of this age rarely
construct clay figures which are noted for their dynamic quality in terms
of finish, proportion, or pose.
This study examined the effect of using a "formative" modelling
technique on the clay models made by 11 year old children. Involved
in the study were two groups of 11 year old children. Both groups of
children undertook a pre-test, a post-test, and a series of clay
modelling activities similar to other activities described in most primary
school art curricula. The experimental group of children were
instructed in the use of a "formative" modelling technique in which
children develop their clay figures from a single mass of clay and
refrain from constructing the figures by a combination of separate
parts. The control group received no instruction.
Brown's Modified "Secondary" Characteristics Rating Scale was used
to identify differences between pre- and post-test clay figures.
Results suggest that the "formative" modelling technique did not induce
a different approach to the modelling of finish, proportion, and pose in
the clay figures made by boys and girls 11 years of age. However,
there was evidence of a gender difference.
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Singh, Peterson Lila Physics Faculty of Science UNSW. "Modelling secondary organic aerosol formation :from chemical mechanistic modelling to empirical modelling." Awarded by:University of New South Wales. Physics, 2007. http://handle.unsw.edu.au/1959.4/40466.
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The work presented in this thesis is primarily concerned with modelling the formation of secondary organic aerosols (SOAs). SOAs cannot easily be measured with direct analytical chemical methods; indirect methods like applying organic carbon to elemental carbon ratios and utilising computer models have been employed to provide an estimate of the SOA mass concentrations in ambient air. The five models presented in this work were either developed or assessed using environmental chamber data. Chamber experiments were undertaken using initial isoprene concentrations in the range of 22 ppb to 343 ppb, with the reactive organic carbon (ROC) to NOx ratios in the range of 2.0 to about 18. Chamber experiments were also performed for the a-pinene / NOx system with initial a-pinene concentrations ranging from 79 ppb to 225 ppb, with ROC/NOx ratios varying from 5.5 to about 41. All of the experiments were performed without the addition of propene or seed aerosol. Background aerosol levels were very low for the experiments presented in the thesis and so homogeneous nucleation processes were considered to occur in the chamber in addition to absorption and oligomerisation formation processes. Initial nucleation events resulting from the photooxidation of isoprene could be detected once the aerosol diameter was greater than 12 nm. In the a-pinene system,new particles formed via homogeneous nucleation processes were detectable in the 100-200nm diameter range. The models presented range in complexity from the near explicit Master Chemical Mechanism to an empirical model whose key feature is its simplicity. The mechanistic model provides an insight into the SOA formation pathways and the influence of varying the initial experimental conditions and the duration of photooxidation on the simulated SOA composition. The aim of the empirical model is to simulate the SOA mass concentration produced during a chamber experiment. The development of the model is intentionally simple so that it can be applied to any hydrocarbon and has been applied successfully to isoprene and a-pinene chamber experiments. In this way, the empirical model is presented as an alternative approach to predicting the temporal variation in SOA mass concentrations. An analysis of the partitioning absorption models developed by Odum et al. (1996) and Hoffmann et al. (1997) has informed the development of the SOA module which has been coupled to a 3D atmospheric model. Embodied within the SOA module is the gas / aerosol partitioning theory which includes the model proposed initially by Pankow et al. (1994) and by Odum et al. (1996).
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Galbraith, J. W. "Modelling the formation of expectations." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381848.
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Cocks, David. "Mathematical modelling of dune formation." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442818.
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This study is concerned with the mathematical modelling of the formation and subsequent evolution of sand dunes, both beneath rivers (fluvial) and in deserts (Aeolian). Dunes are observed in the environment in many different shapes and sizes; we begin by discussing qualitatively how and why the different forms exist. The most important aspect of a successful model is the relationship between the bed shape and the shear stress that the flow exerts on the bed. We first discuss a simple model for this stress applied to fluvial dunes, which is able to predict dune-like structures, but does not predict the instability of a flat bed which we would hope to find. We therefore go on to look at improved models for the shear stress based on theories of turbulent flow and asymptotic methods, using assumptions of either a constant eddy viscosity or a mixing length model for turbulence. Using these forms for the shear stress, along with sediment transport laws, we obtain partial integrodifferential equations for the evolution of the bed, and we study these numerically using spectral methods. One important feature of dunes which is not taken into account by the above models is that of the slip face - a region of constant slope on the downwind side of the dune. When a slip face is present, there is a discontinuity in the slope of the bed, and hence it is clear that flow separation will occur. Previous studies have modelled separated flow by heuristically describing the boundary of the separated region with a cubic or quintic polynomial which joins smoothly to the bed at each end. We recreate this polynomial form for the wake profile and demonstrate a method for including it into an evolution system for dunes. The resulting solutions show an isolated steady-state dune which propagates downstream. From the asymptotic framework developed earlier with a mixing length model for turbulence, we are able, using techniques of complex analysis, to model the shape of the wake region from a purely theoretical basis, rather than the heuristic one used previously. We obtain a Riemann-Hilbert problem for the wake profile, which can be solved using well-known techniques. We then use this method to calculate numerically the wake profile corresponding to a number of dune profiles. Further, we are able to find an exact solution to the wake profile problem in the case of a sinusoidally shaped dune with a slip face. Having found a method to calculate the shear stress exerted on the dune from the bed profile in the case of separated flow, we then use this improved estimate of the shear stress in an evolution system as before. In order to do this efficiently, we consider an alternative method for calculating the wake profile based on the spectral method used for solving the evolution system. We find that this system permits solutions describing an isolated dune with a slip face which propagates downstream without changing shape. All of the models described above are implemented in two spatial dimensions; the wind is assumed to blow in one direction only, and the dunes are assumed to be uniform in a direction perpendicular to the wind flow. While this is adequate to explain the behaviour of transverse dunes, other dune shapes such as linear dunes, barchans, and star dunes are by nature three-dimensional, so in order to study the behaviour of such dunes, the extension of the models to three dimensions is essential. While most of the governing equations generalize easily, it is less obvious how to extend the model for separated flow, due to its reliance on complex variables. We implement some three-dimensional evolution models, and discuss the possibility of modelling three-dimensional flow separation.
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Patterson, Robert Iain Arthur. "Numerical modelling of soot formation." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613176.
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Mohamed, Mohamed Ahmed Ali. "Embankment breach formation and modelling methods." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487677.
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Jupp, Charlotte Elizabeth. "Mathematical modelling of feather germ formation." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543015.
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An, Weidong. "Palsa formation, mathematical modelling and field information." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq26040.pdf.
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Holland, Andrew John. "Mechanistic modelling of blocking formation and decay." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/10963.
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Under atmospheric blocking conditions, the normal passage of storms is interrupted by a region of high-pressure which remains lodged at the end of the storm tracks for periods of a week or more, causing the jet to split and the storms forced to pass around to the north and south, causing anomalous weather conditions over this high-pressure region. Being able to predict when these events occur, how long they will persist, and their eventual decay would be of value to improve weather prediction. This work looks at a simplified idealisation of this situation, with a view to improve understanding of any precursors to such events occurring and their subsequent behaviour. A 2-layer, β-plane, quasi-geostrophic channel model is used to examine the interactions between an upper-layer jet and high-frequency eddies supplied from a wavemaker in the lower layer. For certain initial jets, a dipole similar to an atmospheric block is formed, which remains stable to large-amplitude. By adding a shear to the upper-layer jet, a low-frequency vacillation cycle is induced, whereby the high-frequencies excite a split in the jet, which breaks down due to instability. This instability is demonstrated using a local instability analysis technique, and is also reflected in energy diagnostics. The role of the high-frequency eddies through the various phases of the cycle is also examined. A spherical-geometry model is also used with an aim to help bridge the gap between this highly-simplified model and the real atmosphere. These results suggest that the meridional shear in the upper-level atmospheric jetstream may determine whether blocking would develop, persist or breakdown. The structure of the upper-level jet could be controlled by seasonal variations or large-scale teleconnection patterns.
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Tymms, Vijayan Joseph. "Numerical modelling of rifted continental margin formation." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440766.
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Phillips, Robin R. "Radiative transfer modelling of star formation regions." Thesis, University of Kent, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267438.
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Golanski, Yann. "Modelling the formation of dense cold clouds." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325667.
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Manoussaki, Daphne. "Modelling formation of vascular networks in vitro /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/6763.
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Warrlich, Georg-Mathis Dieter. "3D computer forward modelling of carbonate platform evolution." Thesis, Royal Holloway, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391172.
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Myerscough, Mary Ruth. "A chemotactic model of biological pattern formation." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329983.
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Smith, Matthew Carey. "Modelling star formation and stellar feedback in numerical simulations of galaxy formation." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277830.
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Remarkable progress has been made over the last few decades in furthering our understanding of the growth of cosmic structure. Nonetheless, there remains a great deal of uncertainty regarding the precise details of the complex baryonic physics that regulate galaxy formation. Any theory of star formation in galaxies must encompass the radiative cooling of gas into dark matter haloes, the formation of a turbulent, multiphase interstellar medium (ISM), the efficiency with which molecular gas is able to collapse into cores and ultimately stars, and the subsequent interaction of those stars with the gas through ionizing radiation, winds and supernova (SN) explosions. Given the highly non-linear nature of the problem, numerical simulations provide an invaluable tool with which to study galaxy formation. Yet, even with contemporary computational resources, the inherently large dynamical range of spatial scales that must be tackled makes the development of such models extremely challenging, inevitably leading to the adoption of `subgrid' approximations at some scale. In this thesis, I explore new methods of incorporating the physics of star formation and stellar feedback into high resolution hydrodynamic simulations of galaxies. I first describe a new implementation of star formation and SN feedback that I have developed for the state-of-the-art moving mesh code Arepo. I carry out a detailed study into various classes of subgrid SN feedback schemes commonly adopted in the literature, including injections of thermal and/or kinetic energy, two parametrizations of delayed cooling feedback and a 'mechanical' feedback scheme that injects the appropriate amount of momentum depending on the relevant scale of the SN remnant (SNR) resolved. All schemes make use of individually time-resolved SN events. Adopting isolated disk galaxy setups at different resolutions, with the highest resolution runs reasonably resolving the Sedov-Taylor phase of the SNR, I demonstrate that the mechanical scheme is the only physically well-posed method of those examined, is efficient at suppressing star formation, agrees well with the Kennicutt-Schmidt relation and leads to converged star formation rates and galaxy morphologies with increasing resolution without fine tuning any parameters. However, I find that it is difficult to produce outflows with high enough mass loading factors at all but the highest resolution. I discuss the various possible solutions to this effect, including improved modelling of star formation. Moving on to a more self-consistent setup, I carry out a suite of cosmological zoom-in simulations of low mass haloes at very high resolution, performed to z = 4, to investigate the ability of SN feedback models to produce realistic galaxies. The haloes are selected in a variety of environments, ranging from voids to crowded locations. In the majority of cases, SN feedback alone has little impact at early times even in low mass haloes ($\sim10^{10}\,\mathrm{M_\odot}$ at z = 0). This appears to be due largely to the build up of very dense gas prior to SN events, suggesting that other mechanisms (such as other stellar feedback processes) are required to regulate ISM properties before SNe occur. The effectiveness of the feedback also appears to be strongly dependent on the merger history of the halo. Finally, I describe a new scheme to drive turbulence in isolated galaxy setups. The turbulent structure of the ISM very likely regulates star formation efficiencies on small scales, as well as affecting the clustering of SNe. The large range of potential drivers of ISM turbulence are not fully understood and are, in any case, unlikely to arise ab initio in a whole galaxy simulation. I therefore neglect these details and adopt a highly idealised approach, artificially driving turbulence to produce an ISM structure of my choice. This enables me to study the effects of a given level of ISM turbulence on global galaxy properties, such as the fragmentation scale of the disk and the impact on SN feedback efficiencies. I demonstrate this technique in the context of simulations of isolated dwarfs, finding that moderate levels of turbulent driving in combination with SN feedback can produce a steady-state of star formation rates and global galaxy properties, rather than the extremely violent SN feedback that is produced by a rapidly fragmenting disk.
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Staphorst, Leonard. "The impact of intellectual property rights from publicly financed research and development on governance mode decisions for research alliances." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/24604.
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This study consisted of two distinct research phases, performed within the context of the South African Council for Science and Industrial Research (and its current and potential research alliances). The purpose of the study was to develop a decision making model that would enable strategists at publicly financed research and development organisations to analyse and predict governance mode decisions, as well as select optimal governance mode structures (ranging from quasi-market structures, such as once-off contracts, to quasi-hierarchy structures, such as research joint ventures) for research alliances. During the qualitative first phase, the study aimed to identify impact domains within South Africa’s new Bayh-Dole-like Intellectual Property Rights legislative framework that consists of the Intellectual Property Rights from Publicly Financed Research and Development Act, as well as the Technology Innovation Agency Act, which could potentially influence research alliances (based on the Transactional Cost Economics, Resource-based View and Real Options Approach perspectives) with publicly financed research and development organisations. This was followed by the quantitative second phase, which attempted to verify the validity of a value-mediated governance mode model that included the highest ranked impact domains identified during the first phase as formative indicators for the perceived Intellectual Property Rights regime strength uncertainty factor. A qualitative online survey amongst senior managers at the Council for Science and Industrial Research, followed by Theme Extraction combined with Constant Comparative Method analysis, as well as a weighted frequency analysis, constituted the research methodology employed during the first phase’s identification and ranking of impact domains within the South African legislative framework. This phase demonstrated that the highest ranked impact domains (primarily driven by the Transactional Cost Economics perspective) included the choice of Intellectual Property Rights ownership, state walk-in rights on undeclared Intellectual Property, and benefit-sharing policies for the creators of Intellectual Property. The second phase consisted of a quantitative online survey, distributed amongst current and potential research alliance partners of the Council for Science and Industrial Research, followed by Structural Equation Modelling of a value-mediated governance model that included, amongst others, the perceived Intellectual Property Rights regime strength as an uncertainty factor. This phase revealed not only that the impact domains identified during the first phase could be used as formative indicators of the perceived Intellectual Property Rights regime strength, but also that stronger perceived regimes are positively related to the preference for quasi-hierarchy research alliance governance modes. Furthermore, it established that the expected value of a research alliance, which was shown to be positively influenced by the strength of the perceived Intellectual Property Rights regime, acted as a mediating factor on the relationship between the perceived Intellectual Property Rights regime strength and the preferred research alliance governance mode. Keywords: Bayh-Dole, Formative Indicators, Intellectual Property Rights, Research Alliances, Real Options Approach, Resource-based View, Quasi-Market Governance Modes, Quasi- Hierarchy Governance Modes, Structural Equation Modelling, Transactional Cost Economics, Value-mediated Governance Model. CopyrightDissertation (MBA)--University of Pretoria, 2012.
Gordon Institute of Business Science (GIBS)
unrestricted
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Kesser, André [Verfasser]. "Modelling fibril formation on membrane surfaces / André Kesser." Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1139122940/34.
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Dederichs, Anne S. "Flamelet modelling of soot formation in diffusion flames /." Lund : Univ, 2004. http://www.brand.lth.se.
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Fischer, Thorsten. "Modelling of lipid raft formation in cell membranes." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546490.
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Moroz, Adam. "Reduced order modelling of bone resorption and formation." Thesis, De Montfort University, 2011. http://hdl.handle.net/2086/5409.
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The bone remodelling process, performed by the Bone Multicellular Unit (BMU) is a key multi-hierarchically regulated process, which provides and supports various functionality of bone tissue. It is also plays a critical role in bone disorders, as well as bone tissue healing following damage. Improved modelling of bone turnover processes could play a significant role in helping to understand the underlying cause of bone disorders and thus develop more effective treatment methods. Moreover, despite extensive research in the field of bone tissue engineering, bonescaffold development is still very empirical. The development of improved methods of modelling the bone remodelling process should help to develop new implant designs which encourage rapid osteointegration. There are a number of limitations with respect to previous research in the field of mathematical modelling of the bone remodelling process, including the absence of an osteocyte loop of regulation. It is within this context that this research presented in this thesis utilises a range of modelling methods to develop a framework for bone remodelling which can be used to improve treatment methods for bone disorders. The study concentrated on dynamic and steady state variables that in perspective can be used as constraints for optimisation problem considering bone remodelling or tissue remodelling with the help of the grafts/scaffolds.The cellular and combined allosteric-regulation approaches to modelling of bone turnover, based on the osteocyte loop of regulation, have been studied. Both approaches have been studied different within wide range of rate parameters. The approach to the model validation has been considered, including a statistical approach and parameter reduction approach. From a validation perspective the cellular class of modes is preferable since it has fewer parameters to validate. The optimal control framework for regulation of remodelling has been studied. Future work in to improve the models and their application to bone scaffold design applications have been considered. The study illustrates the complexity of formalisation of the metabolic processes and the relations between hierarchical subsystems in hard tissue where a relatively small number of cells are active. Different types/modes of behaviour have been found in the study: relaxational, periodical and chaotic modes. All of these types of behaviour can be found, in bone tissue. However, a chaotic or periodic modes are ones of the hardest to verify although a number of periodical phenomena have been observed empirically in bone and skeletal development. Implementation of the allosteric loop into cellular model damps other types of behaviour/modes. In this sense it improves the robustness, predictability and control of the system. The developed models represent a first step in a hierarchical model of bone tissue (system versus local effects). The limited autonomy of any organ or tissue implies differentiation on a regulatory level as well as physiological functions and metabolic differences. Implementation into the cellular phenomenological model of allosteric-like loop of regulation has been performed. The results show that the robustness of regulation can be inherited from the phenomenological model. An attempt to correlate the main bone disorders with different modes of behaviour has been undertaken using Paget’s disorder in bone, osteoporosis and some more general skeleton disorders which lead to periodical changes in bone mass, reported by some authors. However, additional studies are needed to make this hypothesis significant. The study has revealed a few interesting techniques. When studying a multidimensional phenomenon, as a bone tissue is, the visualisation and data reduction is important for analysis and interpretation of results. In the study two novel technical methods have been proposed. The first is the graphical matrix method to visualise/project the multidimensional phase space of variables into diagonal matrix of regular combination of two-dimensional graphs. This significantly simplifies the analysis and, in principle, makes it possible to visualise the phase space higher than three-dimensional. The second important technical development is the application of the Monte-Carlo method in combination with the regression method to study the character and stability of the equilibrium points of a dynamic system. The advantage of this method is that it enables the most influential parameters that affect the character and stability of the equilibrium point to be identified from a large number of the rate parameters/constants of the dynamic system. This makes the interpretation of parameters and conceptual verification of the model much easier.
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Ali, Mohamad Azlin. "One-dimensional modelling of hydrate formation in pipelines." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25506.
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Hydrate formation in oil and gas pipelines can be troublesome and often, without a proper remediation, the formation of hydrates can lead to a pipe blockage. As hydrate formation is a non-isothermal process, the modelling of the thermodynamic behaviour of the phases within the flow is proposed. A single energy equation has been formulated and verified with parametric analyses. A new hydrate kinetics routine, based on a two-step hydrate formation mechanism, in an oil-dominated flow is proposed. The first step involves the mass transfer of gas from the free gas phase into the oil (gas dissolution rate) and the second step is the mass transfer of the dissolved gas into the water (gas consumption rate). Suitable models in the form of transport equations for each mechanism, together with appropriate closure relations to account for the agglomeration of hydrate particles and hydrate slurry viscosity, are formulated. Both the energy equation and the hydrate kinetics routine were integrated into an existing in-house research code, TRIOMPH (Transient Implicit One-Dimensional Multiphase). The model was tested and validated against two flow loop experiments, and has shown good agreement. Advancement over the only other existing model in predicting hydrate formation in the heavily slugged hypothetical pipe, has also been shown, giving the current model versatility in simulating both slug and non-slug cases.
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Beattie, Robert Scott. "Side scan sonar image formation, restoration and modelling." Thesis, Robert Gordon University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318551.
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Burridge, Donald Andrew. "Modelling of image formation by synthetic aperture radars." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47372.
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Buzzard, Samantha C. "Modelling melt lake formation on an ice shelf." Thesis, University of Reading, 2017. http://centaur.reading.ac.uk/74826/.
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The accumulation of surface meltwater on ice shelves can lead to the formation of melt lakes. Melt lakes have been implicated in crevasse propagation and ice shelf collapse; the Larsen B ice shelf on the Antarctic Peninsula was observed to have a large amount of melt lakes present on its surface just before its collapse in 2002. Such collapse can affect ocean circulation and temperature, and cause a loss of habitat. Additionally, it can cause a loss of the buttressing effect that ice shelves can have on their tributary glaciers, thus allowing the glaciers to accelerate, contributing to sea level rise. We present results of a 1-D mathematical model of surface melt on an idealised ice shelf. The model incorporates a calculation of the surface energy balance of an ice shelf, heat transfer through the upper ice shelf, the production and percolation of meltwater into the firn, the formation of ice lenses in the firn and the formation, development and refreezing of surface melt lakes on the ice shelf. The melt lake model is applied to the Larsen C Ice Shelf, located on the Antarctic Peninsula, where melt lakes have been observed. The Antarctic Peninsula has warmed several times the global average over the last century and Larsen C has been suggested as a candidate for becoming fully saturated with meltwater by the end of the current century. When forced with automatic weather station data from Larsen C, our model produces surface melting, meltwater accumulation, melt lake development and refreezing consistent with current observations. We examine the sensitivity of lake formation to uncertain parameters, and provide evidence of the importance of processes such as the lateral transport of meltwater (and thus ice shelf topography) to the formation of surface lakes, a process without which lakes were not found to form. Furthermore, we investigate the impact on melt lakes and the surface energy balance of possible future atmospheric conditions.
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Boccara, Bruno 1956. "Modelling choice set formation in discrete choice models." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14324.
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Wallace, Heather A. "Mathematical modelling of wrinkle formation in bacterial biofilms." Thesis, University of Dundee, 2016. https://discovery.dundee.ac.uk/en/studentTheses/5ecaa42d-7299-4d33-a245-45c7f535570a.
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Biofilms are matrix-producing communities of bacterial cells that adhere to surfaces and adopt a multicellular lifestyle. As the predominant life-form of bacteria (estimates suggest that 99% of all bacteria exist in biofilm communities), biofilms play a crucial role in the Earth’s ecosystems, where their existence is known to contribute both beneficial and detrimental effects. One of the defining characteristics of biofilms is heterogeneity in their structure. Indeed, it is commonly observed that biofilms of certain species of bacteria grown under certain conditions can display an unusual wrinkled structure, the pattern of which can vary at different locations throughout the biofilm. It is known that the type of wrinkle morphology displayed can be partially attributed to the expression of particular genes, which also have an effect on the mechanical properties observed in biofilms. Although the functions of wrinkles in biofilms, and the mechanisms controlling their formation, are not fully understood, it is believed that the presence of wrinkles enhances antimicrobial resistance (a property often associated with biofilms). In this thesis we investigate cellular processes and mechanical mechanisms that may contribute to biofilm wrinkle formation. Some emphasis is directed towards the development of wrinkling patterns in biofilms of the Bacillus subtilis bacterium. Particular focus on the role of cell death in initiating pattern formation is explored through the analysis and numerical simulations of mathematical models. In addition we investigate whether classical mathematical tools and techniques that were originally designed to be applied to non-biological structures, and which take into account the mechanical properties of materials, can be implemented and used to explain biofilm wrinkling patterns. Using a mixture of mathematical modelling, analysis and numerical simulations, we conclude that a model description that incorporates the interplay between both biological and mechanical effects may be a useful tool for gaining a better understanding of the biofilm wrinkling process, and thus in the future, may enhance our knowledge of how these complex communities function.
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Hunt, Gordon S. "Mathematical modelling of pattern formation in developmental biology." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2706.
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The transformation from a single cell to the adult form is one of the remarkable wonders of nature. However, the fundamental mechanisms and interactions involved in this metamorphic change still remain elusive. Due to the complexity of the process, researchers have attempted to exploit simpler systems and, in particular, have focussed on the emergence of varied and spectacular patterns in nature. A number of mathematical models have been proposed to study this problem with one of the most well studied and prominent being the novel concept provided by A.M. Turing in 1952. Turing's simple yet elegant idea consisted of a system of interacting chemicals that reacted and di used such that, under certain conditions, spatial patterns can arise from near homogeneity. However, the implicit assumption that cells respond to respective chemical levels, di erentiating accordingly, is an oversimpli cation and may not capture the true extent of the biology. Here, we propose mathematical models that explicitly introduce cell dynamics into pattern formation mechanisms. The models presented are formulated based on Turing's classical mechanism and are used to gain insight into the signi cance and impact that cells may have in biological phenomena. The rst part of this work considers cell di erentiation and incorporates two conceptually di erent cell commitment processes: asymmetric precursor di erentiation and precursor speci cation. A variety of possible feedback mechanisms are considered with the results of direct activator upregulation suggesting a relaxation of the two species Turing Instability requirement of long range inhibition, short range activation. Moreover, the results also suggest that the type of feedback mechanism should be considered to explain observed biological results. In a separate model, cell signalling is investigated using a discrete mathematical model that is derived from Turing's classical continuous framework. Within this, two types of cell signalling are considered, namely autocrine and juxtacrine signalling, with both showing the attainability of a variety of wavelength patterns that are illustrated and explainable through individual cell activity levels of receptor, ligand and inhibitor. Together with the full system, a reduced two species system is investigated that permits a direct comparison to the classical activator-inhibitor model and the results produce pattern formation in systems considering both one and two di usible species together with an autocrine and/or juxtacrine signalling mechanism. Formulating the model in this way shows a greater applicability to biology with fundamental cell signalling and the interactions involved in Turing type patterning described using clear and concise variables.
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Potter, Ross William Kerrill. "Numerical modelling of basin-scale impact crater formation." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9322.
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Understanding of basin-scale crater formation is limited; only a few examples of basin-scale craters exist and these are difficult to access. The approach adopted in this research was to numerically model basin-scale impacts with the aim of understanding the basin-forming process and basin structure. Research was divided into: (1) investigating early stage formation processes (impactor survivability), (2) investigating later stage formation processes (excavation and modification) and basin structure, and (3) constraining an impact scenario for the largest lunar crater, the South Pole-Aitken Basin. Various impact parameters were investigated, quantifying their effect on the basin-forming process. Simulations showed impactor survivability, the fraction of impactor remaining solid during the impact process, greatly increased if the impactor was prolate in shape (vertical length > horizontal length) rather than spherical. Low (≲15 km/s) impact velocities and low impact angles (≲30 ) also noticeably increased survivability. Lunar basin-scale simulations removed a significant volume of crustal material during impact, producing thinner post-impact crustal layers than those suggested by gravity-derived basin data. Most simulations formed large, predominantly mantle, melt pools; inclusion of a steep target thermal gradient and high internal temperatures greatly influenced melt volume production. Differences in crustal thickness between simulations and gravity-derived data could be accounted for by differentiation of the voluminous impact-generated melt pools, predicted by the simulations, into new crustal layers. Assuming differentiation occurs, simulation results were used to predict features such as transient crater size for a suite of lunar basins and tentatively suggest lunar thermal conditions during the basin-forming epoch. Additional simulations concerned the formation of the South Pole-Aitken Basin. By constraining simulation results to geochemical and gravity-derived basin data, a best-fit impact scenario for the South Pole-Aitken Basin was found.
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Mace, Alexander R. "Modelling the formation of ordered acentrosomal microtubule arrays." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/53440/.
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Acentrosomal microtubules are not bound to a microtubule organising centre yet are still able to form ordered arrays. Two clear examples of this behaviour are the acentrosomal apico-basal (side wall) array in epithelial cells and the parallel organisation of plant cortical microtubules. This research investigates their formation through mathematical modelling and Monte Carlo simulations with the software programs developed ourselves. In epithelial cells there is a generally accepted `release and capture' hypothesis for the transfer of centrosomal microtubules onto the side wall array. We use a combination of mathematical and Monte Carlo simulation models to perform the first modelling of this hypothesis. We find that a tubulin concentration dependent dynamic instability is not a good�fit to this hypothesis but that a reduced centrosomal nucleation rate in response to an increased number of side wall microtubules makes the hypothesis work in biologically reasonable conditions. We propose that the loss of nucleation rate is a result of ninein being transferred from the centrosome to the side wall. We show OpenCL to be a useful tool in building a simulation program for parameter searches. We use a Monte Carlo simulation model to investigate how the collision induced catastrophe (CIC) probability affects the formation of the ordered array of cortical plant microtubules. We find that with entrainment an ordered array stops forming once the CIC drops below 0.5. We�find that the severing action of katanin is able to restore order at CIC probabilities below 0.5 but the speed at which crossovers must be severed becomes unfeasibly fast as the CIC decreases. This implies that at very low CICs observed in nature (�0.1), katanin may be necessary but not suffi�cient to create the ordered array. We also provide a customisable and intuitive cortical microtubule simulation software to aid in further research.
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Vaddi, Veera Venkata Sesha Sai. "Modelling and control of satellite formations." [College Station, Tex. : Texas A&M University, 2004. http://hdl.handle.net/1969.1/329.
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Thesis (Ph.D.)--Texas A&M University, 2003."Major Subject: Aerospace Engineering" Title from author supplied metadata (record created on Jul. 18, 2005.) Vita. Abstract. Includes bibliographical references.
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Seymour, J. E. "Crosslinking and network formation in a model polymeric system." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382120.
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Font, Palma Carolina. "Modelling of gasification of poultry litter." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/modelling-of-gasification-of-poultry-litter(e4956eca-d310-4114-89a1-6f44af1aae27).html.
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The poultry industry in Europe is vast and proper waste management is required in order to comply with environmental regulations. As a result, poultry litter represents a potential fuel candidate for thermal conversion technologies since it is an available source. Therefore, a process for the gasification of poultry litter is examined in this study. This process integrates a fluidised bed gasifier with a gas turbine with the aim of generating combustibles gases for energy production. This resulted in a viable solution for a small scale system to be installed on-site the biomass source. The system allows the treatment of waste with the additional benefit of generation of energy, and is suitable for a poultry farm to avoid the transportation of litter to centralised plants. Among the by-products generated during gasification, such as NOx, SO2, and fly ash, tar is a major issue when implementing this technology because tar can cause operational problems as a result of the possible formation of aerosols and soot formation due to repolymerization. A process simulation using Aspen Plus was used to evaluate four levels of integration. The equilibrium model was applied to evaluate integration schemes involving recuperation of energy from the gas turbine exhaust gases. The recuperation of residual heat to preheat air and product gases was performed with the aim of achieving the highest electrical efficiency. For the conventional "atmospheric layout", the fuel gases have to be cooled down before being compressed to the desire pressure, which causes to waste energy from the hot fuel gases. The benefit of the "pressurised layout" is that all process stages can be maintained hot. Process efficiency analyses showed that even when the "atmospheric layout" was set with energy recuperation, the "pressurised layout" delivered higher efficiencies with or without the energy recuperation into the gasifier. After a bibliographic review, the lignin content of biomass was concluded responsible for tar formation because of its aromatic nature. As lignin components, guaiacol, vanillin and catechol were chosen as tar precursors due to its presence in lignin structure. A reaction mechanism and its corresponding kinetics were derived. This mechanism was based on the three-lignin unit decomposition into lighter molecules and greater aromatic rings. Some of the tar products were involved in combustion and/or steam gasification reactions. The tar reaction mechanism was introduced into the kinetic model for the gasification of poultry litter. The results showed agreement with experimental work from previous reports for the evolution of primary tars. However, the model overestimated the total tar concentration. When the model was compared with the equilibrium model, the trends of the main product gases agreed as the air:fuel ratio was varied.
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Órfão, Sandra Maria da Cunha. "Mathematical approaches to modelling and controlling blood thrombin formation." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=984084673.
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Fagerlind, Magnus Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Mathematical modelling of bacterial quorum sensing and biofilm formation." Awarded by:University of New South Wales. Biotechnology & Biomolecular Sciences, 2008. http://handle.unsw.edu.au/1959.4/43095.
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To date, bacterial resistance to antibiotics is an increasing problem and there is a growing appreciation that biofilm formation is a significant contributor to antibiotic resistance. This has led to .increased research on ways to reduce/control biofilm formation. One such target is bacterial cell-cell communication that allows bacteria to coordinate gene expression, and that has been shown to be involved in biofilm formation and production of virulence factors. By interfering with this communication system it should be possible to control gene expression and thus inhibit production of virulence factors as well as the formation of biofilms. However, these processes are multi-factorial, which make it a very complicated task to experimentally identify key parameters that subsequently could guide the development of cell-cell communication strategies to control bacterial virulence and biofilm formation. However, by using mathematical modelling, it is possible to study complex processes and to identify those parameters that are most important for these processes. The focus of this thesis was to develop mathematical models of bacterial cell-cell communication systems and biofilm formation to identify key parameters that could subsequently guide the development of cell-cell communication strategies to control bacterial virulence and biofilm formation. It was found that the cell-cell communication system in the model bacterium Pseudomonas aeruginosa works by hysteretic switching between two stable steady states, reflecting low and high rates of signal production, respectively. It was also shown that this bacterium uses different regulators to adjust the cell density required for switching the system on or off. Moreover, it was also demonstrated that signal antagonists have the capacity to switch the system from an induced state to the lower, uninduced state. However, it was also shown that this blocking behaviour is extremely dependent on the properties of the AHL antagonists, since even very small differences could greatly affect the outcome. Finally, accumulation of damage was predicted to be the main cause of cell death during the formation of biofilms. In addition, a strong relationship between nutrient availability and damage accumulation (and consequently cell death) was also found.
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Chong, Kin Hung. "Modelling and simulation of particle formation in laminar flames." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336552.
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Wright, C. J. "Flavour formation during beer fermentation : modelling higher alcohol production." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636697.
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One of the most important contributions to flavour compounds in beer is that associated with the activity of yeast. A kinetic model that quantitatively predicts the influence of changing process parameters on yeast metabolism and the production of flavour compounds would be invaluable. However a review of the literature has revealed that there is an absence of good quantitative data on which to build a model. The literature uses a wide variety of yeast strains and undefined fermentation media. There is also very little quantitative analysis of flavour formation and the models that have been published have little physiological relevance. The aim of the present study was to develop a kinetic model that would describe the production of the higher alcohols, isoamylalcohol and isobutanol, by the yeast N.C.Y.C 1681 within a brewery fermentation system. H.P.L.C., G.C. and enzyme assay analytical methods were developed that allowed the determination of concentrations of pertinent medium components during a fermentation. Amino acid concentrations were determined using Pico-tag (P.I.T.C.) pre-column derivatisation chemistry. Beer volatile components were analysed using G.C. head space analytical procedures. Yeast growth was studied in experimental defined media and in the complex wort medium. The vessels of the study were stirred tank fermenters, tall tubes and brewery cylindroconicals. Higher alcohol production is intimately linked with the yeast populations amino acid metabolism. Thus the influence of medium nitrogen content was investigated in relation to catabolic and anabolic production of higher alcohols.
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Bird, Katy. "Modelling the star formation histories of nearby elliptical galaxies." Thesis, University of Central Lancashire, 2012. http://clok.uclan.ac.uk/6622/.
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Since Lick indices were introduced in 1994, they have been used as a source of observational data against which computer models of galaxy evolution have been compared. However, as this thesis demonstrates, observed Lick indices lead to mathematical ill-conditioning: small variations in observations can lead to very large differences in population synthesis models attempting to recreate the observed values. As such, limited reliance should be placed on any results currently or historically in the literature purporting to give the star formation history of a galaxy, or group of galaxies, where this is deduced from Lick observations taken from a single instrument, without separate verification from at least one other source. Within these limitations, this thesis also constrains the star formation histories of 21 nearby elliptical galaxies, finding that they formed 13.26 +0.09 -0.06 Gyrs ago, that all mergers are dry, and that galactic winds are formed from AGN activity (rather than being supernovae-driven). This thesis also finds evidence to support the established galaxy-formation theory of “downsizing”. An existing galactic model from the literature is examined and evaluated, and the reasons for it being unable to establish star formation histories of individual galaxies are ascertained. A brand-new model is designed, developed, tested and used with two separate data sets, corroborated for 10 galaxies by data from a third source, and compared to results from a Single Stellar Population model from the literature, to model the star formation histories of nearby elliptical galaxies.
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Newall, Mark John. "Forward and reverse modelling of extensional sedimentary basin formation." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317249.
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Totton, Timothy Stephen. "Modelling interactions of polycyclic aromatic hydrocarbons during soot formation." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610194.
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Rinaldo, Guilherme. "Modelling and control of multiple mobile robots in formation." reponame:Repositório Institucional da UFABC, 2017.
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Orientador: Prof. Dr. Marat RafikovDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Mecânica, 2017.
O presente trabalho trata do controle de multiplos robos moveis enquanto mantem uma formação, atraves do uso do metodo de controle State-Dependent Riccati Equation. Seis robos com chassi diferencial são utilizados em um esquema onde um é considerado o lider e os outros cinco são considerados seguidores. Alterando parametros de formação, este trabalho busca obter cinco formações diferentes: Triangular, Echelon, Linha, Coluna e Quadrangular. Um painel de controle foi criado e simulações foram feitas utilizando o software LabVIEW, demonstrando o sucesso da aplicação do metodo de controle no problema de rastreamento de robos moveis em formação. Este trabalho tambem propõe estrategias anti-colisão para prevenir choques tanto com obstaculos quanto com outros robos. Um algoritmo é criado e implementado com sucesso para evitar colisões.
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Farrell, Fred Desmond Casimir. "Modelling collective behaviour and pattern formation in bacterial colonies." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10452.
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In this Thesis I present simulation- and theory-based studies of pattern formation and growth in collections of micro-organisms, in particular bacterial colonies. The aim of these studies is to introduce simple models of the 'micro-scale' behaviour of bacterial cells in order to study the emergent behaviour of large collections of them. To do this, computer simulations and theoretical techniques from statistical physics, and in particular non-equilibrium statistical physics, were used, as the systems under study are far from thermodynamic equilibrium, in common with most biological systems. Since the elements making up these sytems - the micro-organisms - are active, constantly transducing energy from their environment in order to move and grow, they can be viewed as `active matter' systems. First, I describe my work on a generalization of an archetypal model of active matter - the Vicsek model of flocking behaviour - in which the speed of motion of active particles depends on the local density of particles. Such an interaction had previously been shown to be responsible for some forms of pattern formation in bacterial colonies grown on agar plates in the laboratory. Simulations and theory demonstrated a variety of pattern formation in this system, and these results may be relevant to explaining behaviour observed in experiments done on collections of molecular motors and actin fibres. I then go on to describe work on modelling pattern formation and growth in bacterial biofilms - dense colonies of cells growing on top of solid surfaces. I introduce a simple simulation model for the growth of non-motile cells on a flat surface, whereby they move only by growing and pushing on each other as they grow. Such colonies have previously been observed experimentally to demonstrate a transition from round to 'branched' colonies, with a pattern similar to diffusion-limited aggregation. From these simulations and analytical modelling, a theory of the growth of such colonies is developed which is quite different from previous theories. For example, I find that the colony cannot grow at a constant speed if the cells are not compressible. Finally, I present some results on genetic drift and evolution in growing bacterial colonies. Genetic drift is greatly enhanced in colonies which are expanding in space, as only a few individuals at the edge of the population are able to pass on their genes onto their progeny. The individual-based simulations of biofilms described above are used to analyse which factors - such as the shape of the colony, the thickness of the growing layer of cells, and the interactions between the cells - affect the rate of genetic drift and the probability of fixation of beneficial mutations. This has implications, for example, for the evolution of antibiotic resistance in such colonies.
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Jonsson, Eskil. "Modelling the Formation and Propagation of Orographic Rossby Waves." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325188.
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Orographic Rossby waves are the main mechanism by which the jet streams meander aroundthe Earth and have possibly far-reaching impacts on weather and climate (chapter 1). Hence,they are of particular importance to study and this project should serve as a starting point inwhat to consider when trying to model these waves. For example, we have to account forpressure gradients, Coriolis effect, orography, potential vorticity conservation and also Earth’scurvature at this scale. These are covered in detail in ch. 2 and adapted to the Shallow WaterEquations. In addition, some entry-level numerical techniques for solving these equations arepresented throughout ch. 2.4 and then implemented for the global-scale Shallow WaterEquations with conserved potential vorticity in ch. 3. The model is validated to work for typicalshallow water flows in a bath tub and passes common tests like the Gaussian curve test (ch.4.1). However, when considering atmospheric flows (ch. 4.2) it becomes evident that ourmodel, as well as our numerical methods are lacking and cannot reproduce Rossby waves ina stable manner. Hence, a heavily modified version of Hogan’s model (Hogan, n.d) isemployed with a simplified numerical scheme. With these corrections, orographic Rossbywaves appear to naturally form at appropriate locations. However, they do not fully exhibit theexpected behaviours discussed in ch. 2.2. Even Hogan’s model appears to have severelimitations as waves propagate in the wrong direction. Hence, this study is not complete andwarrants further development in order to be useful.Orografiska Rossby-vågor är den huvudsakliga mekanismen genom vilken jetströmmarnaslingrar runt jorden och kan ha en omfattande inverkan på väder och klimat (kapitel 1). Därförär de av särskild betydelse att studera och detta projekt bör fungera som en utgångspunkt förvad man måste överväga när man försöker modellera dessa vågor. Till exempel så måste vi tahänsyn till tryckgradienter, Coriolis-effekten, orografi, potentiell vorticitetsbevarande och ävenjordens krökning på denna skala. Dessa beskrivs i detalj i kap. 2 och anpassas tillrörelseekvationerna för grunt vatten (Saint-Venant-ekvationerna). Därefter presenteras någranumeriska tekniker på grundläggande nivå för att lösa dessa ekvationer i kap. 2.4, varvid desedan implementeras för de globala Saint-Venant-ekvationerna med bevarad potentiellvorticitet i kap 3. Modellen är validerad för typiska grunda vattenflöden i ett badkar ochpasserar vanliga numeriska tester så som Gauss-kurvtestet (kap. 4.1) och bore-testet. Mennär vi överväger atmosfäriska flöden (kap. 4.2) blir det tydligt att våra modeller och numeriskametoder är primitiva och inte kan reproducera Rossby-vågor på ett stabilt sätt. Därmed,modifierar vi Hogans modell (Hogan, n.d) för att passa vår modell vilket resulterar orografiskaRossby-vågor. Dock så är dessa förskjutna och stämmer inte riktigt överens med teorin i kap.2.2. Även Hogans modell visar sig ha allvarliga begränsningar då vågorna propagerar i felriktning. Därmed är denna studie ej komplett och kräver ytterligare utveckling för att varaanvändbar.
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Dixon, Anthony David George. "Evolution of the Yorkshire, Sole Pit and East Midland basin system, U.K." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6695/.
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The objective of this study is to examine the thermo-mechanical evolution of the Yorkshire(Cleveland), Sole Pit and East Midland Basins, Southern North Sea using theoretical models of basin formation(subsidence) and basin destruction(inversion).Subsidence occurs in response to a driving tectonic force and is amplified by the input of sediments, which impart a load on the Uthosphere. The form of subsidence varies depending on the degree of crustal and sub-crustal involvement. In order to isolate this driving tectonic subsidence the loading effect of the sediments is removed by backstripping. Intrinsic to the accurate modelling of basin formation using this method are firstly, the presence of a complete sedimentary sequence representing the maximum load on the basement and secondly, a normal and representative compaction trend. Subsidence in the Yorkshire, Sole Pit and East Midland Basins was terminated in the late Cretaceous-early Tertiary by inversion. This inversion is demonstrated to have been controlled by pre-existing structures and accommodated differentially within the Yorkshire and Sole Pit Basins in the form of basement uplift and shortening. A significant proportion of the sediments was removed by this uplift. This is quantified by studying compaction trends and is used to reconstruct the basin configuration prior to inversion to facilitate modelling of basin formation. The patterns of subsidence appear to conform well to those predicted by a model of simple lithospheric stretching with a rapid initial subsidence followed by more gentle thermal and flexural subsidence. Superimposed on this background subsidence are discrete events which appear to be related to periods of active faulting or increases in regional loading(eustatic). Subsidence, like inversion, occurs differentially within the fault bounded margins of the Yorkshire and Sole Pit Basins. The relationship between faults at different crustal levels is complicated by stress partitioning by Permo-Triassic salt horizons, yet it does appear that reactivation of Carboniferous and older structures has influenced the geological evolution of these basins.
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Williams, Jennifer Louise. "Modelling the circumstellar environments of massive protostellar objects." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/modelling-the-circumstellar-environments-of-massive-protostellar-objects(192e2f9b-da91-4976-b866-9b012823dfd6).html.
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This thesis investigates the modelling of massive protostellar envelopes in dust and molecular emission. A detailed study is undertaken for a sample of 30 targets believed to contain young high-mass protostars. SCUBA observations of the dust emission are used to help distinguish between the genuine high-mass protostars and clusters of lower mass protostars. Using the single power-law density structure, models are found that fit 16 sources, that are well-separated from other sources, in half of the 30 target regions. Indices of the power-law profiles are compared to values obtained from the literature. The distributions of the indices are similar but there are differences in the underlying distributions which show that observations at longer wavelengths give generally steeper profiles. Investigating the underlying nature of the sources between the fitted and non-fitted sources shows some interesting differences between the groups. These differences indicate that the modelled sources are more likely to be massive protostars while the other sources are probably lower mass protostars. Single power-law modelling is also used to investigate molecular emission in a second group of targets from the RMS survey. Dust models are obtained for six of the sources which show similar results to the sources described above. Molecular line emission from the targets is mapped and compared to the dust emission which shows they trace the same regions. The dust models are used as a basis to obtain the molecular abundances for the sources. Abundances from the modelling the lines are broadly similar values to those observed in other high-mass protostars and association with radio and maser emission indicates that high-mass star formation is definitely occurring in some of these regions.
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Slingerland, Martin Jacob (Marc), and University of Lethbridge Faculty of Arts and Science. "Modelling the auxin-mediated vein formation system in plant leaves." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007, 2007. http://hdl.handle.net/10133/673.
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The plant hormone auxin is involved in a wide range of developmental phenomena in
plants. It carries out many of its effects through a signalling network involving the regulation
of specific genes, including those involved in its own polar transport between cells.
These transporters are able to be redistributed between cell faces, causing the asymmetric
auxin transport that is a key requirement for the formation of vein patterns in leaves.
In this thesis I describe the development of a biochemical kinetics-based model of auxin
signalling and transport in a single cell, which displays biologically plausible responses
to auxin application. The single-cell model then serves as the basis for a multicell model
of auxin-mediated vein formation at a very early stage of leaf formation in Arabidopsis
thaliana.ix, 73 leaves : ill. ; 29 cm.
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Kleiveland, Rune Natten. "Modelling of Soot Formation and Oxidation in Turbulent Diffusion Flames." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-702.
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Soot and radiation play an important role when designing practical combustion devices, and great efforts have been put into developing models which describe soot formation and oxidation. The Eddy Dissipation Concept (EDC) has proven to describe turbulent combustion well, and has the flexibility to describe chemical kinetics in a detailed manner. The aim of this work is to study how the EDC handles soot models based on a detailed representation of the gas-phase chemical kinetics.
Two versions of a semi-empirical soot model is used in conjunction with the EDC. Concentrations of various intermediate species are used as input to the soot models.
The implementation of the new soot models is discussed in relation to the previous implementation of a less detailed soot model. To assure that the interaction between soot and the gas-phase species is represented correctly, the soot models are implemented with a two-way coupling of soot and gas-phase kinetics.
Soot is a good radiator. In a sooting flame a substantial amount of energy will be transferred to the surroundings by thermal radiation. This transfer of energy will alter the temperature field of the flame and the change in temperature will affect the kinetics of soot and gas-phase chemistry. To simulate sooting flames correctly, it was therefore necessary to include a radiation model.
To validate the coupled models of turbulence, combustion, soot, and radiation two different turbulent flames were simulated. One turbulent jet flame of methane and one turbulent jet flame of ethylene. For both flames the computed results were compared with measured values.
Several aspects of the simulations are studied and discussed, such as the effect of the two-way coupling of soot and gas-phase kinetics on both soot yield and gas-phase composition, and the importance of a suitable radiation model.
The two-way coupling of soot and gas phase kinetics is shown to have a positive effect on the computed soot volume fractions, and the results are considered to be encouraging. The work has demonstrated that the EDC has the capacity to handle different types of chemical reaction mechanisms, such as mechanisms for gas-phase combustion and soot kinetics, without modification.