Dissertations / Theses on the topic 'TOV Equation'
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1
Rutstam, Nils. "Study of equations for Tippe Top and related rigid bodies." Licentiate thesis, Linköpings universitet, Tillämpad matematik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-60835.
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The Tippe Top consist of a small truncated sphere with a peg as a handle. When it is spun fast enough on its spherical part it starts to turn upside down and ends up spinning on the peg. This counterintuitive behaviour, called inversion, is a curious feature of this dynamical system that has been studied for some time, but obtaining a complete description of the dynamics of inversion has proved to be a difficult problem. The existing results are either numerical simulations of the equations of motion or asymptotic analysis that shows that the inverted position is the only attractive and stable position under certain conditions. This thesis will present methods to analyze the equations of motion of the Tippe Top, which we study in three equivalent forms that each helps us to understand different aspects of the inversion phenomenon. Our study of the Tippe Top also focuses on the role of the underlying assumptions in the standard model for the external force, and what consequences these assumptions have, in particular for the asymptotic cases. We define two dynamical systems as an aid to understand the dynamics of the Tippe Top, the gliding heavy symmetric top and the gliding eccentric cylinder. The gliding heavy symmetric top is a natural non-integrable generalization of the well-known heavy symmetric top. Equations of motion and asymptotics for this system are derived, but we also show that equations for the gliding heavy symmetric top can be obtained as a limit of the equations for the Tippe Top. The equations for the gliding eccentric cylinder can be interpreted as a special case of the equations for the Tippe Top, and since it is a simpler system, properties of the Tippe Top equations are easier to study. In particular, asymptotic analysis of the gliding eccentric cylinder reveals that the standard model seems to have inconsistencies that need to be addressed.
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Måhl, Anna. "Separation of variables for ordinary differential equations." Thesis, Linköping University, Department of Mathematics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5620.
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In case of the PDE's the concept of solving by separation of variables
has a well defined meaning. One seeks a solution in a form of a
product or sum and tries to build the general solution out of these
particular solutions. There are also known systems of second order
ODE's describing potential motions and certain rigid bodies that are
considered to be separable. However, in those cases, the concept of
separation of variables is more elusive; no general definition is
given.
In this thesis we study how these systems of equations separate and find that their separation usually can be reduced to sequential separation of single first order ODE´s. However, it appears that other mechanisms of separability are possible.
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Heavilin, Justin. "The Red Top Model: A Landscape-Scale Integrodifference Equation Model of the Mountain Pine Beetle-Lodgepole Pine Forest Interaction." DigitalCommons@USU, 2007. https://digitalcommons.usu.edu/etd/7137.
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Under normative conditions the mountain pine beetle (Dendroctonus ponderosae Hopkins) has played a regulating role in healthy lodgepole pine (Pinus contorta) forests. However, recently eruptive outbreaks that result from large pine beetle populations have destroyed vast tracts of valuable forest. The outbreaks in North America have received a great deal of attention from both the timber industry and government agencies as well as biologists and ecologists.
In this dissertation we develop a landscape-scaled integrodifference equation model describing the mountain pine beetle and its effect on a lodgepole pine forest. The model is built upon a stage-structured model of a healthy lodgepole pine forest with the addition of beetle pressure in the form of an infected tree class. These infected trees are produced by successful beetle attack, modelled by response functions. Different response functions reflect different probabilities for various densities. This feature of the model allows us to test hypotheses regarding density-dependent beetle attacks.
To capture the spatial aspect of beetle dispersal from infected trees we employ dispersal kernels. These provide a probabilistic model for finding given beetle densities at some distance from infected trees. Just as varied response functions model different attack dynamics, the choice of kernel can model different dispersal behavior. The modular nature of the Red Top Model yields multiple model candidates. These models allow discrimination between broad possibilities at the land scape scale: whether or not beetles are subject to a threshold effect at the lands cape scale and whether or not host selection is random or directed. We fit the model using estimating functions to two distinct types of data: aerial damage survey data and remote sensing imagery. Having constructed multiple models, we introduce a novel model selection methodology for spatial models based on facial recognition technology.
Because the regions and years of aerial damage survey and remote sensing data in the Sawtooth National Recreation Area overlap, we can compare the results from data sets to address the question of whether remote sensing data actually provides insight to the system that coarser scale but less expensive and more readily available aerial damage survey data does not.
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Yang, Ronghua. "Studies on value distribution of solutions of complex linear differential equations /." Joensuu : Joensuun yliopistopaino, 2006. http://www.loc.gov/catdir/toc/fy0706/2006421381.html.
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Dengiz, Suat. "3+1 Orthogonal And Conformal Decomposition Of The Einstein Equation And The Adm Formalism For General Relativity." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612949/index.pdf.
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In this work, two particular orthogonal and conformal decompositions of the 3+1 dimensional Einstein equation and Arnowitt-Deser-Misner (ADM) formalism for general relativity are obtained. In order to do these, the 3+1 foliation of the four-dimensional spacetime, the fundamental conformal transformations and the Hamiltonian form of general relativity that leads to the ADM formalism, de
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Schulz, Stephan. "Leaning search control knowlledge for equational deduction /." Berlin : AKA, 2000. http://www.loc.gov/catdir/toc/fy0804/2007440965.html.
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Häggström, Johan. "Teaching systems of linear equations in Sweden and China : what is made possible to learn? /." Göteborg : Göteborgs universitet, 2008. http://www.loc.gov/catdir/toc/fy0805/2008380731.html.
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Bernroider, Edward, and Patrick Schmöllerl. "A technological, organisational, and environmental analysis of decision making methodologies and satisfaction in the context of IT induced business transformations." Elsevier, 2013. http://dx.doi.org/10.1016/j.ejor.2012.07.025.
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Although Operational Research (OR) has successfully provided many methodologies to address
complex decision problems, in particular based on the rationality principle, there has been too
little discussion regarding their limited consideration in IT evaluation practice and associated
decision making satisfaction levels in an organisational context. The aim of this paper is to
address these issues through providing a current account of diffusion and infusion of OR
methodologies in IT decision making practice, and by analysing factors affecting decision
making satisfaction from a Technological, Organisational, and Environmental (TOE) framework
in the context of IT induced business transformations. We developed a structural equation model
and conducted an empirical survey, which supported four out of five developed research
hypotheses. Our results show that while Decision Support Systems (DSS), holistic IT evaluation
methods, and management support seem to positively affect individual satisfaction, legislative
regulation has an adverse effect. Results also revealed a persistent methodology diffusion and
infusion gap. The paper discusses implications in each of these aspects and presents opportunities
for future work. (authors' abstract)
9
Rippeyoung, Phyllis Love Farley. "Is it too late baby? pinpointing the emergence of a black-white test score gap in infancy." Diss., University of Iowa, 2006. http://ir.uiowa.edu/etd/80.
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El-Kafri, Manal M. Lutfi. "Symmetry methods applied to Richard's equations and problems of infiltration." Thesis, University of South Wales, 2006. https://pure.southwales.ac.uk/en/studentthesis/symmetry-methods-applied-to-richards-equations-and-problems-of-infiltration(e94a3a66-f16b-46cd-a9c8-192ac6b995bc).html.
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Water resources development around the world has taken many different forms and directions since the dawn of civilization. Water shortage in arid and semiarid regions has encouraged the search for additional sources currently not exploited intensively. Hence, knowledge of the infiltration process is a requirement for understanding water management. The main aim here is to solve the one-dimensional nonlinear time-dependent Richard's equation for water flow in an unsaturated uniform soil. The main theory of soil infiltration is introduced using a mathematical-physical approach to describe water movement in unsaturated soils. This gives rise to Richard's flow equation; which is presented for both unsaturated and also saturated soil. Methods for solving Richard's equation by both analytical and numerical techniques are then introduced. This gives rise to a discussion of the similarity methods first used by Philip to determine analytical solutions of Richard's equation in an unsaturated soil. This is then generalised to determine a broader class of solutions using the Lie (classical) symmetry approach. The non-classical symmetries of Bluman and Cole are also determined. Although these group methods provide the most widely applicable technique to find solutions of ordinary and partial differential equations, a large number of tedious calculations are involved. With the help of computer algebra it is shown that the determining equations for the non-classical case lead to four new highly non-linear equations which are solved in five particular cases. Each case of classical and non-classical solutions is then reduced to an ordinary differential equation and explicit solutions are produced when possible. The potential classical and non-classical method, first suggested by Bluman, Reid and Kumei, is also discussed and presented. The potential non-classical method produced new results, which the potential classical method did not. The solution is useful as a tool by which to judge the quality of numerical methods. A practical solution of classical (Lie/ potential) and non-classical symmetry of Richard's equation is presented. Finally, conclusions and suggestions for further work are discussed.
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Turchi, Alessio. "Dynamics and statistics of systems with long range interactions : application to 1-dimensional toy-models." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4810/document.
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L'objectif de ce thèse est l'étude des systèmes dynamiques avec interaction à longue portée. La complexité de leur dynamique met en évidence des propriétés contre-intuitives et inattendues, comme l'existence d'états stationnaires hors-équilibre (QSS). Dans le QSS on peut observer des propriétés particulières: chaleur spécifique négative, inéquivalence des ensembles statistiques et phénomènes d'auto-organisation. Les théories des interactions LR ont été appliquées pour décrire la dynamique des systèmes auto-gravitants, de tourbillons bidimensionnels, de systèmes avec interactions onde-particule et des plasmas chargés. Mon travail s'est tout d'abord consacré à l'extension de la solution de Lynden-Bell pour le modèle HMF, en généralisant l'analyse à des conditions initiales de «water-bag" à plusieurs niveaux, qui approchent des conditions initiales continues. En suite je me suis intéressé à la caractérisation formelle de la thermodynamique des QSS dans l'ensemble statistique canonique. En appliquant la théorie standard, il est possible de mesurer une chaleur spécifique "cinétique'' négative. Cette propriété inattendue amène à la violation du second principe de la thermodynamique. Un tel résultat nous pousse à reconsidérer l'applicabilité de la théorie thermodynamique actuelle aux systèmes LR. En suite j'ai étudié, pour le modèle α-HMF, la persistance des caractéristiques typiques du régime LR, dans le limite dynamique à courte portée. Les résultats suggèrent une généralisation de la définition des systèmes LR. Le dernier chapitre est consacré à la caractérisation d'un nouveau modèle LR, extension naturelle du précédent α-HMF et d'intérêt potentiel applicatifThe scope of this thesis is the study of systems with long-range interactions (LR). The complexity of their dynamics evidences counter-intuitive and unexpected properties, as for instance the existence of out-of-equilibrium stationary states (QSS). Considering a system in the QSS, one may observe peculiar properties, as negative specific heat, statistical ensemble inequivalence and phenomena of self-organizations. The main theories of long-range interactions have been applied to describing self-gravitating systems, two-dimensional vortices, systems with wave-particle interactions and charged plasmas. My work has been initially dedicated to extending the Lynden-Bell solution for the HMF model, generalizing the analysis to multi-level water-bag initial condition that could approximate continuous distributions. Then I concentrated to the formal characterization of the thermodynamics of QSS in the canonical statistical ensemble. By applying the standard theory, it is possible to measure negative “kinetic” specific heat. This latter unexpected property leads to a violation of the second principle of thermodynamics. Such result forces us to reconsider the applicability of the accepted thermodynamic theory to LR systems. Afterwards I studied, in the context of the α-HMF model, the persistence of the typical characteristics of the LR regime in the limit of short-range dynamics. The results obtained suggests a generalization of the definition of LR systems. The last chapter is dedicated to the characterization of a novel LR model, a natural extension of α-HMF and of potential applicability
12
Alkahtani, Badr. "Numerical solutions to the Navier-Stokes equations in two and three dimensions." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/numerical-solutions-to-the-navierstokes-equations-in-two-and-three-dimensions(be2b37ea-74af-432e-9ee5-193dd7b28d3b).html.
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In this thesis the solutions of the two-dimensional (2D) and three-dimensional (3D) lid-driven cavity problem are obtained by solving the steady Navier-Stokes equations at high Reynolds numbers. In 2D, we use the streamfunction-vorticity formulation to solve the problem in a square domain. A numerical method is employed to discretize the problem in the x and y directions with a spectral collocation method. The problem is coded in the MATLAB programming environment. Solutions at high Reynolds numbers are obtained up to $Re=25000$ on a fine grid of 131 * 131. The same method is also used to obtain the numerical solutions for the steady separated corner flow at high Reynolds numbers are generated using a for various domain sizes, at various Reynolds number which are much higher than those obtained by other researchers.Finally, the numerical solutions for the three-dimensional lid-driven cavity problem are obtained by solving the velocity-vorticity formulation of the Navier-Stokes equations for various Reynolds numbers. A spectral collocation method is employed to discretize the y and z directions and finite difference method is used to discretize the x direction. Numerical solutions are obtained for Reynolds number up to 200.
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Lotfy, Mohamed Abdalla Mohamed Badreldin. "Sustainability of Enterprise Resource Planning (ERP) Benefits Postimplementation: An Individual User Perspective." ScholarWorks, 2015. https://scholarworks.waldenu.edu/dissertations/1316.
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Although there is research about the use of enterprise resource planning (ERP) from a management perspective, the research is not clear as to whether the ERP benefits justify the costs, not only in dollars, but also in effort, from the end user's perspective. Using the theory of diffusion of innovation (DOI), the purpose of this quantitative research was to identify the set of postimplementation sustainability factors that maximized ERP user value, which are major issues for management, and measured their relative significance. The study's structural model incorporated the technology-organization-environment (TOE) framework, which is a conceptualization of the theory of diffusion of innovation, to predict the postimplementation sustainability factors from the ERP user's point of view. The partial least squares structure equation modeling (PLS-SEM) approach provided the needed explanatory analysis to test the predictive power of the structural model. The target population was organizational employees who had used an operational ERP system for at least 4 years in the state of Colorado. A convenience sample of 163 cases responded to the online questionnaire. Hypotheses testing indicated that the independent variables of ERP information quality, ERP system quality, ERP knowledge and learning, shared beliefs, job relevance, and coordination significantly impacted the dependent variable ERP user value. The positive social change implications of this study include a better understanding of ERP postimplementation sustainability factors from the users' perspectives and their social impact on organizational performance, which could lead to increased employee effectiveness, productivity, efficiency, and individual satisfaction due to ERP usage.
14
Bourne, Thomas. "Applications of the virial equation of state to determining the structure and phase behaviour of fluids." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/applications-of-the-virial-equation-of-state-to-determining-the-structure-and-phase-behaviour-of-fluids(809267a4-117a-49a2-9e36-44baa5f12860).html.
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This work considers the extent to which the virial expansion can describe the structure and phase behaviour of several model fluids. These are the hard-sphere fluid, inverse-power potential fluids, the Lennard-Jones fluid and two kinds of 'square-shoulder' potential. The first novel contribution to knowledge that this work makes is in using virials to obtain the direct correlation function of a hard-core inverse-power potential fluid at densities close to freezing. Predicted radial distribution functions for the fluid at these densities are found that agree well with integral equation theory and simulation data. For softer-core potentials, a convergent direct correlation function is obtained at densities up to those at which a convergent virial expansion is known to exist. The study then extends to a Lennard-Jones fluid. At super-critical temperatures, a convergent direct correlation function is found as before. However, at sub-critical temperatures, the direct correlation function is found to diverge at all points for densities below criticality. Several recently-proposed re-summations of the pressure virial expansion are studied to improve its convergence at high densities. Some promise is shown in improving the accuracy of the virial expansion at high densities, but a re-summed virial expansion is found to be unable to fully capture the true behaviour of the system at densities close to criticality. A second novel contribution to knowledge is made by the reporting of virial coefficient data for several dissipative particle dynamics and penetrative square well potential forms. This is used to study the effect of re-summing the virial expansion for these systems in order to improve its convergence at high densities. The virial expansions of these potentials are found to perform increasingly poorly in the proximity of a vapour-liquid phase transition. This is in agreement with the results of investigating the Lennard-Jones fluid. Thirdly, this investigation considers the whether the virial expansion can describe the freezing of a hard sphere fluid and therefore predict the entire phase diagram for this system. This is investigated using a virial expansion to model the excess contribution to the Helmholtz energy functional. The virial expansion is not found to be able to accurately the point of phase transition, most likely due to questions remaining over the choice of a Gaussian basis set to describe lattice.
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Nytra, Jan. "Řešení problémů akustiky pomocí nespojité Galerkinovy metody." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232174.
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Parciální diferenciální rovnice hrají důležitou v inženýrských aplikacích. Často je možné tyto rovnice řešit pouze přibližně, tj. numericky. Z toho důvodu vzniklo množství diskretizačních metod pro řešení těchto rovnic. Uvedená nespojitá Galerkinova metoda se zdá jako velmi obecná metoda pro řešení těchto rovnic, především pak pro hyperbolické systémy. Naším cílem je řešit úlohy aeroakustiky, přičemž šíření akustických vln je popsáno pomocí linearizovaných Eulerových rovnic. A jelikož se jedná o hyperbolický systém, byla vybrána právě nespojitá Galerkinova metoda. Mezi nejdůležitější aspekty této metody patří schopnost pracovat s geometricky složitými oblastmi, možnost dosáhnout metody vysokého řádu a dále lokální charakter toho schématu umožnuje efektivní paralelizaci výpočtu. Nejprve uvedeme nespojitou Galerkinovu metodu v obecném pojetí pro jedno- a dvoudimenzionalní úlohy. Algoritmus následně otestujeme pro řešení rovnice advekce, která byla zvolena jako modelový případ hyperbolické rovnice. Metoda nakonec bude testována na řadě verifikačních úloh, které byly formulovány pro testování metod pro výpočetní aeroakustiku, včetně oveření okrajových podmínek, které, stejně jako v případě teorie proudění tekutin, jsou nedílnou součástí výpočetní aeroakustiky.
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Ježková, Jitka. "Modelování dopravního toku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232180.
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Tato diplomová práce prezentuje problematiku dopravního toku a jeho modelování. Zabývá se především několika LWR modely, které následně rozebírá a hledá řešení pro počáteční úlohy. Ukazuje se, že ne pro všechny počáteční úlohy lze řešení definovat na celém prostoru, ale jen v určitém okolí počáteční křivky. Proto je dále odvozena metoda výpočtu velikosti tohoto okolí a to nejen zcela obecně, ale i pro dané modely. Teoretický rozbor LWR modelů a řešení počátečních úloh jsou demonstrovány několika příklady, které zřetelně ukazují, jak se dopravní tok simulovaný danými modely chová.
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Crouch, Matthew. "Luminosity performance limitations due to the beam-beam interaction in the Large Hadron Collider." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/luminosity-performance-limitations-due-to-the-beambeam-interaction-in-the-large-hadron-collider(287b2265-a67d-406a-8c94-0fc193e2401b).html.
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In the Large Hadron Collider (LHC), particle physics events are created by colliding high energy proton beams at a number of interaction points around the ring. One of the main performance indicating parameters of the LHC is the luminosity. The luminosity is limited by, amongst other things, the strength of the beam-beam interaction. In this thesis, the effect of the beam-beam interaction on the luminosity performance of the LHC and the proposed High Luminosity Large Hadron Collider (HL-LHC) is investigated. Results from a number of dedicated, long-range beam-beam machine studies are presented and analysed. In these studies, the minimum beam-beam separation for two different beta star optics are identified. This separation defines the minimum operational crossing angle in the LHC. The data from these studies are then compared to simulation of the dynamic aperture and the results are discussed. In addition to studies of the LHC, an analytical approach is derived in order to describe the hourglass effect, which may become a contributing factor in limiting the luminosity performance of the HL-LHC.
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Skillen, Alex. "The overset grid method, applied to the solution of the incompressible Navier-Stokes equations in two and three spatial dimensions." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/the-overset-grid-method-applied-to-the-solution-of-the-incompressible-navierstokes-equations-in-two-and-three-spatial-dimensions(dc7ced62-3132-4404-a006-314766a93146).html.
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The generation of structured grids around complex geometries is generally a difficult task. Thistask is typically a major bottleneck in the overall solution procedure; however, the overset gridmethod can be used to relieve much of this burden. An overset grid consists of a set of simplecomponent grids, which can overlap arbitrarily (provided there is sufficient overlap to interpolatefrom). The union of all simple grids should then delineate the global domain. This allows complex domains to meshed using a series of simple meshes. Interpolation boundary conditions are enforced at internal boundaries to ensure a continuous solution. Standard tri-linear interpolation is typically used for this purpose, although there are alternative methods that attempt to enforce global conservation. A new CFD code has been developed that incorporates the overset grid method in three spatialdimensions. This code uses the steady state, finite volume discretisation method. SIMPLE pressure velocity coupling has been used on a colocated grid with Rhie-Chow interpolation for face velocities. Different interpolation methods have been compared for the information transfer at internal boundaries from one grid to the next. It has been shown that for a variety of test cases, continuous and accurate solutions are obtained from one grid to another, which are comparable to those of the single-block or block-structured solutions, or to experimental data (where available). A new hole cutting algorithm and bulk correction outlet condition are presented. Improvements to existing digital tree data structures are also described. Lid driven cavity flow, the flow around rotating cylinders, and flow impingement onto a concavesurface are considered in order to demonstrate the method. The flow over a backward facing step, over a multi-element airfoil, through a bifurcating artery and over a wing-body junction are then considered (with experimental comparison). This demonstrates the range of applicability of the method. In all cases, the overset method offers significant advantages over block-structured solutions that are available in the literature. It is shown that greater numerical efficiency is generally achievable via the use of an overset simulation: Since the gridding is flexible, high aspect ratio cells need not propagate into the domain (as is often the case for a block-structured arrangement). Also, much of the domain away from localised regions of geometrical complexity can be meshed with efficientCartesian grids.
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Hudson, Joanna Louise. "Do diabetes cognitions and poor emotional health predict adherence to diabetes self-care? : a longitudinal test of the Common Sense Self-Regulation Model using Structural Equation Modelling." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/do-diabetes-cognitions-and-poor-emotional-health-predict-adherence-to-diabetes-selfcare-a-longitudinal-test-of-the-common-sense-selfregulation-model-using-structural-equation-modelling(c50b5f3a-0950-4862-9d6c-dd32021e74c2).html.
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Depression and anxiety are prevalent in adults with diabetes and are associated with poorer adherence to diabetes self-care. The Common Sense Self-Regulation Model (CS-SRM) hypothesises that both illness cognitions and emotions determine adherence to health behaviours but little is known about the causal pathways through which poor emotional health impairs adherence. Using the CS-SRM as a theoretical framework this thesis aimed to identify the pathways that exist between diabetes cognitions and poor emotional health and explored their combined and independent effects on diabetes self-care. A systematic review with meta-analysis identified that all previous observational studies used cross-sectional designs to explore the relationships between diabetes cognitions and poor emotional health, excluding one. Randomised controlled trials showed that changes in diabetes cognitions were associated with changes in poor emotional health but these mechanisms of action were not confirmed by mediation analyses. Few observational studies have rigorously tested how diabetes cognitions and poor emotional health operate together to determine diabetes self-management behaviours. This thesis used a longitudinal design to test whether: i) diabetes cognitions and poor emotional health have a longitudinal bi-directional relationship and ii) diabetes cognitions and poor emotional health have a combined (mediated) and independent (direct) longitudinal effect on diabetes self-care. Outpatients with Type 2 diabetes (N=261) were recruited at baseline and completed self-report measures of poor emotional health (Well-being Questionnaire), cognitions (Revised Illness Perception Questionnaire; Beliefs about Medicines Questionnaire) and diabetes self-care (Summary of Diabetes Self-Care Activities Scale) at baseline and six months follow-up. Hypothesised pathways were tested simultaneously using structural equation modelling. Participants who were more anxious at baseline perceived diabetes to be unpredictable and were apprehensive about their medications at follow-up. These effects were not observed for depression. Baseline diabetes cognitions did not predict change in poor emotional health at follow-up. Equally, neither baseline depression or anxiety predicted change in diabetes self-care behaviours at six months (directly or indirectly via diabetes cognitions). Baseline personal control beliefs remained independent of poor emotional health: greater personal control beliefs were associated with reduced adherence to diabetes self-care. A bi-directional relationship between diabetes cognitions and poor emotional health was absent in this sample. The main direction of effect was from anxiety only to diabetes cognitions. Depression and anxiety had no relationship with diabetes self-care. Whilst personal control remained independent of poor emotional health, mastery beliefs appear to be insufficient on their own to sustain adherence behaviours over time suggesting that interventions should also provide patients with action plans whilst managing outcome expectations. The unexpected findings for the relationship between poor emotional health, cognitions, and diabetes self-care may be because the sample did not include individuals with more severe depression or anxiety. This study needs to be replicated among people experiencing clinically significant levels of depression and anxiety in diabetes.
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Davis, Sarah Kate. "Multidimensional pathways to adolescent resilience : the case for emotional intelligence." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/multidimensional-pathways-to-adolescent-resilience-the-case-for-emotional-intelligence(80fa6787-a439-466b-8720-eadb8e2fd0e3).html.
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Emotional intelligence (EI) has been reliably associated with better mental health (Martins, Ramalho, & Morin, 2010) however the nature of this relationship in adolescence remains largely unexplored. The small body of existing adolescent research is disproportionately focussed upon the ‘trait’ versus ‘ability’ EI perspective and the association with mood (versus behavioural) disorders in the form of simple, descriptive relationships that reveal little about the processes underpinning such adaptive outcomes. This research redresses this imbalance and advances the field by examining how (whether directly or indirectly linked to known stress-illness processes) and when (under which stress conditions) EI (in both ‘forms’) might be associated with better adolescent mental health, whilst simultaneously exploring the conceptualisation of EI within this developmental period. Adult literature is equivocal on both fronts. Firstly, evidence points to differential incremental contributions from ability and trait EI in the prediction of internalising versus externalising symptomatology beyond known correlates of performance, i.e., personality and cognitive ability (e.g., Gardner & Qualter, 2010; Peters, Kranzler, & Rossen, 2009). Secondly, whilst there is some evidence to suggest that trait EI may directly attenuate the effects of chronic and acute stressors to promote adaptation (e.g., Mikolajczak, Roy, Luminet, Fillée, & de Timary, 2007), the role of ability EI in this regard appears unclear (e.g., Matthews et al., 2006). Indirect links to adjustment are also hinted at; coping mediates trait EI-health outcomes in youth though not all EI-influenced ‘adaptive’ coping styles (e.g., problem-focussed) appear to contribute to this effect (e.g., Downey, Johnston, Hansen, Birney, & Stough, 2010). Using cross-sectional, self-reported data from 1,170 adolescents (mean age = 13.03 years; SD = 1.26) the present research aimed to address this lack of clarity. Preliminary regression analyses found that collectively, EI made a significant, incremental contribution to the prediction of depression and disruptive behaviour in youth beyond the influence of higher-order personality dimensions and general cognitive ability. However, of the two, trait EI appeared the stronger predictor. Structural equation modelling of conditional indirect effects found that whilst both forms of EI can buffer the effects of stressors (family dysfunction, negative life events, socio-economic adversity) on disorder, the mechanisms by which this beneficial effect operates differs substantially according to context - effects appear contingent on stressor, health outcome and level of EI. For depression, ability EI influences the selection of avoidant coping when facing family dysfunction and negative life events, whilst trait EI modifies the effectiveness of active coping under family dysfunction only. In contrast, EI directly attenuates the effects of stressors on disruptive behaviour. Nevertheless, the results of supplementary path analyses augur for the importance of both forms of EI in adaptational processes; actual emotional skill (as ability EI) appears dependent on perceived competency (trait EI) to realise advantageous outcomes. Implications for the EI construct and related intervention programmes are discussed together with recommendations for progression of the field.
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Mohd, Damanhuri Nor Alisa. "The numerical approximation to solutions for the double-slip and double-spin model for the deformation and flow of granular materials." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/the-numerical-approximation-to-solutions-for-the-doubleslip-and-doublespin-model-for-the-deformation-and-flow-of-granular-materials(9986ac45-e48c-4061-a299-a80b2e665c3e).html.
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The aim of this thesis is to develop a numerical method to find approximations to solutions of the double-slip and double-spin model for the deformation and flow of granular materials. The model incorporates the physical and kinematic concepts of yield, shearing motion on slip lines, dilatation and average grain rotation. The equations governing the model comprise a set of five first order partial differential equations for the five dependent variables comprising two stress variables, two velocity components and the density. For steady state flows, the model is hyperbolic and the characteristic directions and relations along the characteristics are presented. The numerical approximation for the rate of working of the stresses are also presented. The model is then applied to a number of granular flow problems using the numerical method.
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Andallah, Laek Sazzad Babovsky Hans. "A hexagonal collision model for the numerical solution of the Boltzmann equation /." 2005. http://www.gbv.de/dms/ilmenau/toc/48386739X.PDF.
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Richter, Christoph. "Proposal of new object-oriented equation-based model libraries for thermodynamic systems /." 2008. http://www.gbv.de/dms/bs/toc/568720776.pdf.
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Costa, Sérgio Luís Ferreira. "Development of advanced components for safety footwear - Integrated manufacturing methodology driven by impact events in mechanical design." Doctoral thesis, 2021. http://hdl.handle.net/1822/75989.
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Programa Doutoral em Engenharia MecânicaA biqueira de proteção trata-se de um componente integrante do calçado de segurança como Elemento de Proteção Individual, com caraterísticas técnicas de resistência mecânica exigidas segundo um contexto normativo. Tal, condiciona o desenvolvimento do conceito de produto. O presente trabalho de investigação, em associação com o projeto cofinanciado S3 – Safety Slim Shoe, almejou o desenvolvimento de uma abordagem multidisciplinar para um novo modelo de alta performance com metas relevantes em modelação concetual e na redução de peso. O estudo de propriedades qualificadas de resistência ao impacto explorou o potencial de soluções combinadas de aços avançados de alta resistência com modelos geométricos para o endurecimento localizado. A resposta estrutural sob uma acentuada otimização de espessura foi avaliada, possibilitando assim, uma discussão orientada na procura de melhorias em modelos com capacidade de absorção de energia. Três materiais distintos UHSS ferrítico-martensíticos foram selecionados e desenvolveu-se a modelação numérica com foco na elevada deformação plástica e na influência de diferentes taxas de deformação. A relação matemática do comportamento dinâmico foi analisada através da aplicação de dois modelos fundamentais constitutivos: A equação de Cowper-Symonds e a equação de Johnson-Cook. Os resultados experimentais obtidos a partir de testes à tração segundo diferentes intervalos de taxa de deformação foram utilizados de forma a determinar parâmetros constitutivos para a caraterização dos materiais. Estes modelos de material foram incorporados em rotinas de simulação numérica de eventos dinâmicos com recurso ao software ANSYS (Explicit Dynamics). A análise com elementos finitos e o desempenho experimental em protótipos reais foram aplicados a dois modelos de biqueira S3, devidamente selecionados a partir do programa de desenvolvimento S3, segundo diferentes variantes combinadas de material e espessura, para uma avaliação de desempenho, a sua adequação e a precisão obtida. Os resultados numéricos e experimentais promoveram uma caracterização comportamental consistente com modelos de deformação que contribuíram, de forma crítica, para a maturidade de desempenho dos protótipos finais. Apresenta-se e valida-se assim um novo componente – biqueira de proteção – que atesta um rácio, melhorado e eficiente, de absorção de energia ao impacto por unidade de peso.
The safety toe cap is a key integrant component in the professional footwear from Personal Protective Equipment (PPE) with demanding strength and technical features according to normative requirements. These factors have been strongly conditioning the product concept. The presented research work in association with the co-financed project S3 – Safety Slim Shoe planned to develop an integrated approach for an ultimate high-performance toe cap model with significant milestones in slim design and weight saving. The study of crashworthiness properties was performed through impact-crash test conditions exploring the potential of applicant solutions by the combination of advanced high-strength steels and enhanced geometric stiffening models. The structural response for a significant thickness reduction was in-depth assessed and provided an evolved discussion for improvements in energy absorption capacity. Three different UHSS steels were selected and numerical modelling with extensive plastic deformation and strain-rate dependence was performed. The mathematical description of the dynamic plasticity behaviour was examined by applying two fundamental constitutive models: the Cowper-Symonds and Johnson-Cook constitutive equations. Experimental results of tensile testing at different strain rate ranges of interest were obtained to further determine fundamental constitutive parameters for the material characterization. These studied material models were incorporated and used in the numerical simulation of impact events using the explicit dynamics software ANSYS. FEA results were compared with the experimental test performance achieved by experimental toe cap prototypes made from a S3 prototype manufacturing program. In this context, two ultimate S3 toe cap models with different combinations of material and thickness optimization were considered and the accuracy and adequacy of the equivalent numerical predictions were evaluated. The comparison of the numerical and experimental results allowed to develop a consistent description of the material behaviour, the deformation pattern of structural models, and thus contributing with critical inputs for the final prototype development. A local stiffening toe cap solution with high energy absorption efficiency is presented and validated in this study.
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Kyncl, Martin. "Numerické řešení třírozměrného stlačitelného proudění." Doctoral thesis, 2011. http://www.nusl.cz/ntk/nusl-311427.
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Title: Numerical Solution of the Three-dimensional Compressible Flow Author: Martin Kyncl Department: Department of Numerical Mathematics Supervisor: Doc. RNDr. Jiří Felcman, CSc. Abstract: This thesis deals with a fluid flow in 3D in general. The system of the equations, describing the compressible gas flow, is solved numerically, with the aid of the finite volume method. The main purpose is to describe particular boundary conditions, based on the analysis of the incomplete Riemann problem. The analysis of the original initial-value problem shows, that the right hand-side initial condition, forming the Riemann problem, can be partially replaced by the suitable complementary condition. Several modifications of the Riemann problem are introduced and analyzed, as an original result of this work. Algorithms to solve such problems were implemented and used in code for the solution of the compressible gas flow. Numerical experiments documenting the suggested methods are performed. Keywords: compressible fluid flow, the Navier-Stokes equations, the Euler equations, boundary conditions, finite volume method, the Riemann problem, numerical flux, tur- bulent flow