Dissertations / Theses: 'Impact – Mathematical models'

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Moore, Matthew Richard. "New mathematical models for splash dynamics." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c94ff7f2-296a-4f13-b04b-e9696eda9047.

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In this thesis, we derive, extend and generalise various aspects of impact theory and splash dynamics. Our methods throughout will involve isolating small parameters in our models, which we can utilise using the language of matched asymptotics. In Chapter 1 we briefly motivate the field of impact theory and outline the structure of the thesis. In Chapter 2, we give a detailed review of classical small-deadrise water entry, Wagner theory, in both two and three dimensions, highlighting the key results that we will use in our extensions of the theory. We study oblique water entry in Chapter 3, in which we use a novel transformation to relate an oblique impact with its normal-impact counterpart. This allows us to derive a wide range of solutions to both two- and three-dimensional oblique impacts, as well as discuss the limitations and breakdown of Wagner theory. We return to vertical water-entry in Chapter 4, but introduce the air layer trapped between the impacting body and the liquid it is entering. We extend the classical theory to include this air layer and in the limit in which the density ratio between the air and liquid is sufficiently small, we derive the first-order correction to the Wagner solution due to the presence of the surrounding air. The model is presented in both two dimensions and axisymmetric geometries. In Chapter 5 we move away from Wagner theory and systematically derive a series of splash jet models in order to find possible mechanisms for phenomena seen in droplet impact and droplet spreading experiments. Our canonical model is a thin jet of liquid shot over a substrate with a thin air layer trapped between the jet and the substrate. We consider a variety of parameter regimes and investigate the stability of the jet in each regime. We then use this model as part of a growing-jet problem, in which we attempt to include effects due to the jet tip. In the final chapter we summarise the main results of the thesis and outline directions for future work.

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Banan, Roshan Aerospace Civil &amp Mechanical Engineering Australian Defence Force Academy UNSW. "An engineering approach to modelling ballistic impact on hybrid polymer laminates." Publisher:University of New South Wales - Australian Defence Force Academy. Information Technology & Electrical Engineering, 2009. http://handle.unsw.edu.au/1959.4/44094.

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Hybrid polymer laminates of polycarbonate and PMMA have generated considerable interest among researchers as an alternative to traditional glass armours because of their potential for reduced cost and weight. Generally, the development of ballistic armour is carried out experimentally which is an expensive task in terms of time and cost. Numerical simulation provides a much greater facility to understand the phenomenon of ballistic impact and the effects of various parameters on the response to such impact. In addition it provides an easy means of comparing the impact performance of different materials as well as combination of materials forming hybrid laminates. The aim of this research was to develop a numerical modelling capability to simulate the ballistic response of hybrid polymer laminates, specifically polycarbonate and PMMA, using a commercially available finite element code LS-DYNA. The challenge was to work within the limitations of the material models and the failure algorithms available within LS-DYNA, and still try to reproduce the behaviour observed experimentally by previous researchers, initially on monolithic plates of polycarbonate and PMMA and then on hybrid laminates. The first part of the study focuses on a detailed literature survey on mechanical and dynamic characterisation of polycarbonate and PMMA as well as experimental and numerical studies previously conducted on ballistic behaviour of these materials as well as their combinations. The material properties of the polymers compiled from this literature survey were used as input for the selected LS-DYNA material model. Impact simulations were carried on monolithic and laminated media of polycarbonate and PMMA and where possible these were compared to experimental results. It was observed that the results agreed with the experimental data qualitatively. Quantitatively the results showed some discrepancies which were attributed to the limitations faced in simulating the exact test conditions numerically. Numerical simulations were carried out to study the effects of variations in laminate thickness and plate support diameters as well as to examine the influence of the bond between the layers. Finally the impact response of four different combinations of polycarbonate and PMMA are compared to each other for different laminate thicknesses.

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Nicholls, Rochelle Louise. "Mathematical modelling of bat-ball impact in baseball." University of Western Australia. School of Human Movement and Exercise Science, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0016.

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[Formulae and special characters can only be approximated here. Please see the pdf version of the abstract for an accurate reproduction.] Ball-impact injuries in baseball, while relatively rare, have the potential to be catastrophic. These injuries are primarily attributed to impact by the ball after it has been hit, pitched or thrown. As the closest infielder to the hitter, the pitcher is at greatest risk of being struck by the batted ball. This thesis investigated the influence of bat and ball design on ball exit velocity (BEV) and the potential for impact injury to pitchers. Finite element analysis (FEA) was used to quantify the dynamics of bat-ball impact for bats of various moment of inertia and baseballs with different mechanical properties. The analysis was conducted using ANSYS/LSDYNA explicit dynamics software. To replicate a typical bat-ball impact in the field, the model required input of bat linear and angular velocity and orientation in three-dimensional (3-D) space, at the instant prior to impact. This data was obtained from 3-D kinematic analysis using two high-speed video cameras operating at 200 Hz. Seventeen high-performance batters used a wood bat and a metal bat of equal length and mass to hit baseballs thrown by a pitcher. Hitters developed significantly higher resultant linear velocity for both the proximal (38.3 ± 1.8 ms-1;) and distal (8.1 ± 1.8 ms-1) ends of the metal bat (compared with 36.4 ± 1.7 ms-1 and 6.9 ± 2.1 ms-1 respectively for the wood bat). They also achieved a significantly more “square” bat position just prior to impact with the ball (264.3 ± 9.1 deg compared with 251.5 ± 10.4 deg). These factors are important in transferring momentum to the batted ball. Mathematical description of the large-deformation material behaviour of the baseball was also required for this analysis. Previous research is limited to compression tests to 10 % of ball diameter, despite conjecture that during impact with the bat, the ball might deform to 50 % of its original diameter. Uniaxial quasi-static compression tests on seven models of baseballs investigated baseball behaviour during deformation to 50 % of ball diameter. The resulting force-displacement relationship was highly non-linear. Hence FEA was used to derive and verify a relationship to describe the time-dependent and elastic behaviour of the ball during the 1 ms period typical of bat-ball impact. The results of the bat-ball impact analysis indicated that for hits made at the point of maximum momentum transfer on the bat, the metal bat produced greater BEV than the wood bat (61.5 ms-1 and 50.9 ms-1 respectively). The higher BEV from the metal bat was attributed to greater pre-impact bat linear velocity, and bat orientation during impact. The more perpendicular horizontal orientation of the metal bat at the instant of impact resulted in a greater proportion of resultant BEV being directed in the global x-direction (toward the pitcher), compared with the wood bat. This indicates increasing bat moment of inertia (the relative mass of the bat barrel) may be a potential control strategy for BEV. BEV was also reduced for impacts using a baseball with values for instantaneous shear and relaxed modulii approximately 33 % less (9.9 % reduction in BEV for metal bat, 9.7 % for the wood bat).

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Wilson, Stephen K. "The mathematics of ship slamming." Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:7bc325cf-e6a1-45d2-add2-100d9968354c.

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Motivated by the motion of a ship in a heavy sea, a mathematical model for the vertical impact of a two-dimensional solid body onto a half-space of quiescent, inviscid, incompressible fluid is formulated. No solutions to the full problem are known, but in the case when the impacting body has small deadrise angle (meaning that the angle between the tangent to the profile and the horizontal is everywhere small) a uniformly valid solution is obtained by using the method of matched asymptotic expansions. The pressure on the body is calculated and is in fair agreement with experimental results. The model is generalised for more complicated impacts and the justifications for the model are discussed. The method is extended to three-dimensional bodies with small deadrise angle and solutions are obtained in some special cases. A variations! formulation of the leading order outer problem is derived, which gives information about the solution and leads to an fixed domain scheme for calculating solutions numerically. A partial linear stability analysis of the outer problem is given which indicates that entry problems are stable but exit problems are unstable to small perturbations. A mathematical model for the effect of a cushioning air layer between the body and the fluid is presented and analysed both numerically and in appropriate asymptotic limits. Finally, the limitations of the models are discussed and directions for future work indicated.

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Modarres, Najafabadi Seyed Ali. "Dynamics modelling and analysis of impact in multibody systems." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115886.

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In this thesis, we discuss a novel approach to the dynamics modelling and analysis of impact in unilaterally constrained multibody systems. This approach is based on an analysis of energy absorption and restitution during impact, using a decomposition technique, which decouples the kinetic energy associated with the spaces of admissible and constrained motions of unilateral contacts. This is done based on the decomposition of the tangent space of the configuration manifold at the pre-impact instant. The decomposition of the kinetic energy can provide a picture of how the energy absorption and dissipation during impact is related to the variation of the generalized velocities and the configuration of multibody systems. Further, based on the above analysis approach, we introduce a new interpretation of the energetic coefficient of restitution, specially applicable to contact involving multibody systems. This interpretation generalizes the concept of the energetic coefficient of restitution and allows for consideration of simultaneous multiple-point contact scenarios. Moreover, based on the concept of the generalized energetic coefficient of restitution, the contact modes and the post-impact state of planar single-point impact are determined. Further, the problem of simultaneous multiple-point impact is considered, where it is shown that our approach can also be advantageous to characterize the dynamics of interaction in such systems. The use and applicability of the approach reported are further investigated by conducting an experimental study on a robotic testbed. The open architecture of the testbed allows us to perform various contact experiments, such as single- and multiple-point impact scenarios, with different pre-impact configurations and velocities. The kinematic and dynamic models of the system have been developed and implemented for real-time analysis. It is shown that impact between multibody systems is considerably affected by not only the local dynamics characteristics of the interacting bodies, but also the (global) configuration of the interacting multibody systems. The reported results suggest that the material presented herein offers a useful means to characterize impact in complex systems.

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Lepage, Thomas. "The impact of variable evolutionary rates on phylogenetic inference : a Bayesian approach." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103264.

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In this dissertation, we explore the effect of variable evolutionary rates on phylogenetic inference. In the first half of the thesis are introduced the biological fundamentals and the statistical framework that will be used throughout the thesis. The basic concepts in phylogenetics and an overview of Bayesian inference are presented in Chapter 1. In Chapter 2, we survey the models that are already used for rate variation. We argue that the CIR process---a diffusion process widely used in finance---is the best suited for applications in phylogenetics, for both mathematical and computational reasons. Chapter 3 shows how evolutionary rate models are incorporated to DNA substitution models. We derive the general formulae for transition probabilities of substitutions when the rate is a continuous-time Markov chain, a diffusion process or a jump process (a diffusion process with discrete jumps). The second half of the thesis is dedicated to applications of variable evolutionary rate models in two different contexts. In Chapter 4, we use the CIR process to model heterotachy, an evolutionary hypothesis according to which positions of an alignment may evolve at rates that vary with time differently from site to site. A comparison the CIR process with the covarion---a widely-used heterotachous model---on two different data sets allows us to conclude that the CIR provides a significantly better fit. Our approach, based on a Bayesian mixture model, enables us to determine the level of heterotachy at each site. Finally, the impact of variable evolutionary rates on divergence time estimation is explored in Chapter 5. Several models, including the CIR process are compared on three data sets. We find that autocorrelated models (including the CIR) provide the best fits.

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Baggaley, Rebecca Frances. "The impact of antiretroviral use in resource-poor settings : insights from mathematical models." Thesis, Imperial College London, 2006. http://hdl.handle.net/10044/1/11778.

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Movahedi-Lankarani, Hamid. "Canonical equations of motion and estimation of parameters in the analysis of impact problems." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184490.

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The transient dynamic analysis of constrained mechanical systems may require the solution of a mixed set of algebraic and differential equations of motion. The usual formulation of these equations is expressed in terms of the accelerations of the system components. A canonical form of the equations of motion in terms of the system velocities and the time derivative of the system momenta may be used instead. This is a natural form of the equations in which all the state variables are explicitly expressed, and have the same physical importance. The numerical solution obtained from the canonical equations shows more accuracy and stability, specifically for systems with large and fluctuating forces. For the mechanical systems that undergo an impact, the usual numerical solution of the equations of motion is not valid. Two different methods of analysis of impact problems are presented. In one method, the variations of the impulsive force during the contact period are directly added to the vector of forces in the canonical equations of motion. In the second method, based on the assumption of instantaneous nature of impact, a set of momentum balance-impulse equations is derived by explicitly integrating the canonical equations. These equations are solved at the time of impact for the jump in the system momenta right after impact. Necessary parameters are evaluated for the performance of the two methods of analysis. These parameters include the maximum relative indentation, the maximum contact force, and the coefficient of restitution. The parameters are determined for the collision between two bodies in a system with any general geometric or material properties. The influence of friction modeling in the magnitude and the direction of the total force at the contact surfaces is discussed. The dynamics of a vehicle collision is studied in order to illustrate the efficiency of obtaining a solution to the canonical equations, the simplicity of solving the momentum balance-impulse equations.

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Njagarah, Hatson John Boscoh. "Modelling water-borne infections : the impact of hygiene, metapopulation movements and the biological control of cholera." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95972.

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Thesis (PhD)--Stellenbosch University, 2014. ENGLISH ABSTRACT: Water-borne infections have been a menace in many countries around the globe, claiming millions of lives. Cholera in particular has spread to all continents and now on its seventh epidemic. Although control measures have been continually developed through sanitation, vaccination and rehydration, the infection still devastates populations whenever there is an outbreak. In this research work, mathematical models for cholera transmission dynamics with focus on the impact of sanitation and hygiene, metapopulation spread, optimal control and biological control using a bacteriophage specific for pathogenic Vibrio cholerae are constructed and analysed. Vital analyses for the models are precisely given as well as numerical results depicting long term behaviour and the evolution of populations over time. The results of our analysis indicate that; improved sanitation and hand-hygiene are vital in reducing cholera infections; the spread of disease across metapopulations characterised by exchange of individuals and no cross community infection is associated with synchronous fluctuation of populations in both adjacent communities; during control of cholera, the control measures/efforts ought to be optimal especially at the beginning of the epidemic where the outbreak is often explosive in nature; and biological control if well implemented would avert many potential infections by lowering the concentration of pathogenic vibrios in the aquatic environment to values lower than the infectious dose. AFRIKAANSE OPSOMMING: Water-infeksies is ’n bedreiging in baie lande regoor die wêreld en eis miljoene lewens. Cholera in die besonder, het op sy sewende epidemie na alle kontinente versprei. Hoewel beheermaatreëls voortdurend ontwikkel word deur middel van higiëne, inentings en rehidrasie, vernietig die infeksie steeds bevolkings wanneer daar ’n uitbraak voorkom. In hierdie navorsingswerk, word wiskundige modelle vir cholera-oordrag dinamika met die fokus op die impak van higiëne, metabevolking verspreiding, optimale beheer en biologiese beheer met behulp van ’n bakteriofaag spesifiek vir patogene Vibrio cholerae gebou en ontleed. Noodsaaklike ontledings vir die modelle is gegee sowel as numeriese resultate wat die langtermyn gedrag uitbeeld en die ontwikkeling van die bevolking oor tyd. Die resultate van ons ontleding dui daarop dat; verbeterde higiëne is noodsaaklik in die vermindering van cholera infeksies; die verspreiding van die siekte oor metapopulaties gekenmerk deur die uitruil van individue en geen kruis gemeenskap infeksie wat verband houmet sinchrone skommeling van bevolkings in beide aangrensende gemeenskappe; tydens die beheer van cholera,behoort die beheermaatreëls/pogings optimaal te wees veral aan die begin van die epidemie waar die uitbreking dikwels plofbaar in die natuur is; en biologiese beheer, indien dit goed geïmplementeer word, kan baie potensiële infeksies voorkom deur ’n vermindering in die konsentrasie van patogene vibrio in die water tot waardes laer as die aansteeklike dosis.

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Shepard, William Steve Jr. "The impact of attached feature scales and spatial distributions on the response of structural-acoustic systems." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/18911.

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Ddumba, Hassan. "Repulsive-attractive models for the impact of two predators on prey species varying in anti-predator response." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/d1010995.

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This study considers the dynamical interaction of two predatory carnivores (Lions (Panthera leo) and Spotted Hyaenas (Crocuta crocuta)) and three of their common prey (Buffalo (Syncerus caffer), Warthog (Phacochoerus africanus) and Kudu (Tragelaphus strepsiceros)). The dependence on spatial structure of species’ interaction stimulated the author to formulate reaction-diffusion models to explain the dynamics of predator-prey relationships in ecology. These models were used to predict and explain the effect of threshold populations, predator additional food and prey refuge on the general species’ dynamics. Vital parameters that model additional food to predators, prey refuge and population thresholds were given due attention in the analyses. The stability of a predator-prey model for an ecosystem faced with a prey out-flux which is analogous to and modelled as an Allee effect was investigated. The results highlight the bounds for the conversion efficiency of prey biomass to predator biomass (fertility gain) for which stability of the three species ecosystem model can be attained. Global stability analysis results showed that the prey (warthog) population density should exceed the sum of its carrying capacity and threshold value minus its equilibrium value i.e., W >(Kw + $) −W . This result shows that the warthog’s equilibrium population density is bounded above by population thresholds, i.e., W < (Kw+$). Besides showing the occurrence under parameter space of the so-called paradox of enrichment, early indicators of chaos can also be deduced. In addition, numerical results revealed stable oscillatory behaviour and stable spirals of the species as predator fertility rate, mortality rate and prey threshold were varied. The stabilising effect of prey refuge due to variations in predator fertility and proportion of prey in the refuge was studied. Formulation and analysis of a robust mathematical model for two predators having an overlapping dietary niche were also done. The Beddington-DeAngelis functional and numerical responses which are relevant in addressing the Principle of Competitive Exclusion as species interact were incorporated in the model. The stabilizing effect of additional food in relation to the relative diffusivity D, and wave number k, was investigated. Stability, dissipativity, permanence, persistence and periodicity of the model were studied using the routine and limit cycle perturbation methods. The periodic solutions (b 1 and b 3), which influence the dispersal rate (') of the interacting species, have been shown to be controlled by the wave number. For stability, and in order to overcome predator natural mortality, the nutritional value of predator additional food has been shown to be of high quality that can enhance predator fertility gain. The threshold relationships between various ecosystem parameters and the carrying capacity of the game park for the prey species were also deduced to ensure ecosystem persistence. Besides revealing irregular periodic travelling wave behaviour due to predator interference, numerical results also show oscillatory temporal dynamics resulting from additional food supplements combined with high predation rates.

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Duhaut, Thomas H. A. "Wind-driven circulation : impact of a surface velocity dependent wind stress." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101117.

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The use of an ocean surface velocity dependent wind stress is examined in the context of a 3-layer double-gyre quasigeostrophic wind-driven ocean circulation model. The new wind stress formulation results in a large reduction of the power input by the wind into the oceanic circulation. This wind stress is proportional to a quadratic function of Ua--u o, where Ua is the wind at 10m above the ocean surface and uo is the ocean surface current. Because the winds are typically faster than the ocean currents, the impact of the ocean surface velocity on the wind stress itself is relatively small. However, the power input is found to be greatly reduced with the new formulation. This is shown by simple scaling argument and numerical simulations in a square basin. Our results suggest that the wind power input may be as much as 35% smaller than is typically assumed. The ocean current signature is clearly visible in the scatterometer-derived wind stress fields. We argue that because the actual ocean velocity differs from the modeled ocean velocities, care must be taken in directly applying scatterometer-derived wind stress products to the ocean circulation models. This is not to say that the scatterometer-derived wind stress is not useful. Clearly the great spatial and temporal coverage make these data sets invaluable. Our point is that it is better to separate the atmospheric and oceanic contribution to the stresses. Finally, the new wind stress decreases the sensitivity of the solution to the (poorly known) bottom friction coefficient. The dependence of the circulation strength on different values of bottom friction is examined under the standard and the new wind stress forcing for two topographic configurations. A flat bottom and a meridional ridge case are studied. In the flat bottom case, the new wind stress leads to a significant reduction of the sensitivity to the bottom friction parameter, implying that inertial runaway occurs for smaller values of bottom friction coefficient. The ridge case also gives similar results. In the case of the ridge and the new wind stress formulation, no real inertial runaway regime has been found over the range of parameters explored.

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Kirkpatrick, Raelene. "A mathematical analysis of the financial and medical impact of hepatitis C among drug users in Perth, Western Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/1332.

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The ability of public health planners continues to be hampered by uncertainties encountered with transmissible diseases. Key epidemiological factors such as, how many Western Australian injecting drug users are hepatitis C seropositive or will become infected, duration of intravenous drug use, the intensity of infection, the fraction of those infected that will develop end-stage disease and after how long a period, all combine to limit the ability of a mathematical model to predict future trends. These models can, however, provide information about certain epidemiological parameters and identify data required to predict future trends. They can be applied to make predictions about the course of infection in the individual and provide a guide to the interpretation of the observed data. This research aims to develop a model of the transmission and spread of hepatitis C, adapting existing models used to predict the spread of HIV and AIDS in one and two sex communities. This model will be used to demonstrate the dynamics and incidence of hepatitis C infection among injecting drug users in Perth, Western Australia. Predictions derived from the model will then be used to undertake an analysis of the cost of treating those with hepatitis C and cirrhosis related complications, resulting in a prediction of the financial impact of hepatitis C on the Western Australian community.

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Denholm, Scott J. "Mathematical models for investigating the long-term impact of Gyrodactylus salaris infections on Atlantic salmon populations." Thesis, University of Stirling, 2013. http://hdl.handle.net/1893/17021.

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Gyrodactylus salaris Malmberg, 1957, is a notifiable freshwater ecto-parasite that infects both wild and farmed populations of Atlantic salmon (Salmo salar, L.). It has caused catastrophic damage to wild salmon stocks in Norway since its accidental introduction in 1975, reducing salmon density in some rivers by 98% over a period of five years. It is estimated that G. salaris has cost the Norwegian salmon industry more than 500 million EUR. Currently the UK has G. salaris free status under EU law, however, it is believed that if G. salaris emerged in the UK the impact would be similar to that witnessed in Norway. The aim of this thesis is to develop mathematical models that describe the salmon-G. salaris system in order to gain a greater understanding of the possible long-term impact the parasite may have on wild populations of Atlantic salmon in G. salaris-free territories such as the UK. Mathematical models, including deterministic, Leslie matrix and individual based models, were used to investigate the impact of G. salaris on Atlantic salmon at the individual and population level. It is known that the Atlantic strain of Atlantic salmon, examples of which occur naturally in Norway and the UK, does not have any resistance to G. salaris infections and the parasite population is able to quickly grow to epidemic levels. In contrast, the Baltic strain of Atlantic salmon, examples of which occur naturally in Sweden and Russia, exhibits some form of resistance and the parasite is unable to persist. Thus, baseline models were extended to include immunity to infection, a trade-off on salmon reproductive rate, and finally, to consider interactions between populations of G. salaris and multiple strains of salmon exhibiting varying levels of immunity from fully susceptible to resistant. The models proposed predict that in the absence of host resistance or an immune response infections by G. salaris will result in an epidemic followed by the extinction of the salmon host population. Models also predict that if salmon are able to increase their resistance to G. salaris infections through mutations, salmon population recovery after the epidemic is indeed possible within 10-15 years post introduction with low level parasite coexistence. Finally, models also highlight areas where additional information is needed in order to improve predictions and enable the estimation of important parameter values. Model predictions will ultimately be used to assist in future contingency planning against G. salaris outbreaks in the UK and possibly as a basis for future models describing other fish/ecto-parasite systems.

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Worton, Adrian J. "Using mathematical models to understand the impact of climate change on tick-borne infections across Scotland." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/24918.

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Ticks are of global interest as the pathogens they spread can cause diseases that are of importance to both human health and economies. In Scotland, the most populous tick species is the sheep tick Ixodes ricinus, which is the vector of pathogens causing diseases such as Lyme borreliosis and Louping-ill. Recently, both the density and spread of I. ricinus ticks have grown across much of Europe, including Scotland, increasing disease risk. Due to the nature of the tick lifecycle they are particularly dependent on environmental factors, including temperature and habitat type. Because of this, the recent increase in tick-borne disease risk is believed to be linked to climate change. Many mathematical models have been used to explore the interactions between ticks and factors within their environments; this thesis begins by presenting a thorough review of previous modelling of tick and tick-borne pathogen dynamics, identifying current knowledge gaps. The main body of this thesis introduces an original mathematical modelling framework with the aim to further our understanding of the impact of climate change on tick-borne disease risk. This modelling framework takes into account how key environmental factors influence the I. ricinus lifecycle, and is used to create predictions of how I. ricinus density and disease risk will change across Scotland under future climate warming scenarios. These predictions are mapped using Geographical Information System software to give a clear spatial representation of the model predictions. It was found that as temperatures increase, so to do I. ricinus densities, as well as Louping-ill and Lyme borreliosis risk. These results give a strong indication of the disease risk implications of any changes to the Scottish environment, and so have the potential to inform policy-making. Additionally, the models identify areas of possible future research.

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Zeng, Ning. "Climatic impact of Amazon deforestation: A study of underlying mechanism through simple modeling." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186999.

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An intermediate level model for tropical climatology including atmosphere-land-ocean interaction is developed. The model contains basically linearized steady state primitive equations with simplified thermodynamics. A simple hydrological cycle is also included. Special attention has been paid to land surface processes in attempting to study climate change caused by Amazon deforestation. In comparison with previous simple modeling work on tropical climatology or anomaly, the present model is more sophisticated in the sense that it predicts all the important meteorological variables with little input, while being computationally simple. The modeled tropical climatology appears to be realistic. The model generally better simulates the ENSO anomaly compared to many previous simple model simulations. We provide analysis of model results and discuss model deficiencies and possible improvements of the model. The climatic impact of Amazon deforestation is studied in the context of this model. Model results show a much weakened Atlantic Walker/Hadley circulation as a result of the existence of a strong positive feedback loop in the atmospheric circulation system and the hydrological cycle. The regional climate is very sensitive to albedo change and sensitive to evapotranspiration change. The pure dynamical effect of surface roughness on convergence is small, but the surface flow anomaly displays intriguing features. Analysis of the thermodynamic equation reveals the balance among convective heating, adiabatic cooling and radiation largely determines the deforestation response. The model provides a plausible mechanism for the common results of many GCM simulations. Studies of the consequences of hypothetical continuous deforestation suggest that the replacement of forest by desert may be able to sustain a desert-like climate. When a simple mixed layer ocean model is coupled with the atmospheric model, the results suggest a 1 °C decrease in SST gradient across the equatorial Atlantic ocean in response to Amazon deforestation. The magnitude of the decrease depends on the coupling strength.

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Clements, Adam. "The impact and measurement of the intensity of noise in stock returns." Thesis, Queensland University of Technology, 2002.

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The development of financial economics literature has been characterised by a continual dialogue between empirical and theoretical researchers. Often, this dialogue has taken the form of empirical observation prompting theoretical enquiry. This thesis follows this long tradition by investigating a number of emerging empirical facts, for which in most cases, simple theoretical explanations are suggested. Broadly speaking, this thesis investigates the manner in which the level of activity in an asset market influences the empirical features exhibited by the asset's returns. Motivated by these empirical observations reported in this thesis, theoretical models based on heterogeneous trader behaviour are suggested as explanations of these observations. A body of widely accepted empirical facts are first re-evaluated with reference to three representative equity indices. Features such as linear dependence in expected returns, dependence in the volatility of returns and negative correlation between returns and volatility innovations are found to be common characteristics of index returns. A number of authors have documented the emerging fact that the presence of non-linearity in returns is transitory in nature. A central issue of this thesis is to propose a rationale for this as yet unexplained phenomenon. Within a model of trader interaction, it is shown that the intensity of noise trading is critically important for the presence of nonlinear price outcomes. Increases in the intensity of noise trading are shown to extinguish non-linear structure in simulated returns. Analysis of index returns lends support to this notion in that periods of returns that exhibit more intense noise are associated with linearity. Issues relating to the accurate and efficient measurement of noise are discussed in detail. It is found that when dealing with stock returns, simple standard deviation of returns is a valid approximation to the intensity of noise in returns. As the presence of non-linearity in returns does not appear to be a persistent feature, the link between market activity and linear dependence in returns is also investigated. Using a similar model of trader interaction, it is shown that when the rate of news arrival is relatively low (high) strong (weak) positive autocorrelations are detected. Broadly consistent patterns are also detected in index returns, supporting the notion that news influences the behavioural patterns of investors and thus observed structure in returns. Another emerging empirical fact documented in this thesis is the manner in which the intensity of noise in returns influences dependence in the volatility of returns. An accepted feature of the dependence in volatility is that an asymmetry exists between returns and volatility innovations. It is shown here that during periods where the intensity of noise in returns is relatively high, this asymmetrical effect becomes more pronounced. While no formal explanation of this observation is suggested, this exercise has followed in the tradition of much research in investigating empirical phenomena as a first step in expanding our understanding of asset markets. The results reported throughout this thesis are important from two perspectives. First, they expand upon our knowledge of the empirical features of asset returns in that emerging facts are re-evaluated and new facts documented. Second, given the theoretical explanations proposed for these observations, insights into the behavioural mechanisms generating returns are also revealed.

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Zhao, Chun. "Impact of convection and lightning on the tropospheric chemistry composition over North America and air quality studies over East Asia." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28114.

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Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2009. Committee Chair: Yuhang Wang; Committee Member: Armistead Russell; Committee Member: Athanasios Nenes; Committee Member: Greg Huey; Committee Member: Judith Curry.

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Nault, Barrie R. "Modelling strategic information technology impact on inter-firm competition: pricing." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30787.

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This research studies normative pricing strategies for information technology (IT) used by suppliers to supplement an underlying primary good. Transactions with consumers and customer firms are considered. Characteristics of IT are divided into IT impacts on customers, and IT impacts on suppliers. IT impacts on customers include vertical differentiation or reduced turnover costs for the primary good, and positive IT adoption costs. IT impacts on suppliers include reduced production costs for the primary good, and the costs of IT. Optimal pricing for the IT and the primary good is modelled for monopoly, and Bertrand competition based on IT and the primary good is modelled for oligopoly. Two part tariffs are used for the IT and IT enhanced primary good. Results of pricing to consumers show that the fixed component of an optimal (or equilibrium) two part tariff can either be a net tax or a net subsidy, confirming the possibility of taxed or subsidized IT adoption. For the monopolist offering the IT and IT enhanced primary good only, the consumer's adoption/switching cost limits the possible subsidy. Consistent with previous economics research, in a duopoly where one supplier has IT, the IT supplier abandons the original primary good. Two suppliers with identical IT cannot attain a positive profit equilibrium. Analogous results obtain for a special case of pricing to customer firms. Empirical results support differential (premium) pricing for an IT enhanced primary good over an original good. Business, Sauder School of Operations and Logistics (OPLOG), Division of Graduate

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Fahy, Benjamin. "Evaluating the Impact and Distribution of Stormwater Green Infrastructure on Watershed Outflow." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4732.

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Green Stormwater Infrastructure (GSI) has become a popular method for flood mitigation as it can prevent runoff from entering streams during heavy precipitation. In this study, a recently developed neighborhood in Gresham, Oregon hosts a comparison of various GSI projects on runoff dynamics. The study site includes dispersed GSI (rain gardens, retention chambers, green streets) and centralized GSI (bioswales, detention ponds, detention pipes). For the 2017-2018 water year, hourly rainfall and observed discharge data is used to calibrate the EPA's Stormwater Management Model to simulate rainfall-runoff dynamics, achieving a Nash-Sutcliffe efficiency of 0.75 and Probability Bias statistic of 3.3%. A synthetic scenario analysis quantifies the impact of the study site GSI and compares dispersed and centralized arrangements. Each test was performed under four precipitation scenarios (of differing intensity and duration) for four metrics: runoff ratio, peak discharge, lag time, and flashiness. Design structure has significant impacts, reducing runoff ratio 10 to 20%, reducing peak discharge 26 to 68%, and reducing flashiness index 56 to 70%. There was a reverse impact on lag time, increasing it to 50 to 80%. Distributed GSI outperform centralized structures for all metrics, reducing runoff ratio 22 to 32%, reducing peak discharge 67 to 69%, increasing lag time 133 to 500%, and reducing flashiness index between 32 and 62%. This research serves as a basis for researchers and stormwater managers to understand potential impact of GSI on reducing runoff and downstream flooding in small urban watersheds with frequent rain.

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Spilotros, Asia. "The Impact of Implementing Different Cordon Size Designs on Land Use Patterns in Portland, OR." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/5095.

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The purpose of this research dissertation is to compare the effects of using small, medium, and large cordon designs in road tolling on residential and commercial neighborhoods in Portland, Oregon. Changes in land use patterns are assessed by comparing the projected output of each cordon scenario to a "no toll" alternative in 2035. The performance of each cordon design is tested using two different prices ($1.65 and $8) and compared to a default scenario 25 years after the initial implementation in MetroScope's year 0, 2010. The following areas embedded within the cordon perimeter were considered in determining changes in land use: all the zones closest to the boundaries, the entire city of Portland, and the neighborhood towns surrounding Portland. Understanding the impact of choosing the "right" cordon size on economic development and residential location choices can be of utmost interest to lawmakers when they assess economic development policies. Unanswered questions remain regarding the impact a cordon scheme has on economic development and business location decisions, as well as its effect on the spatial pattern in the city. While studies on optimal toll pricing are abundant, there are very few studies that determine the optimal cordon location and size for a particular network. Accordingly, a critical question is whether cordon pricing will influence the centralization or decentralization of land use and affect jobs, population, and economic activities. The implementation of a cordon scheme is expected to affect areas both inside and outside of the designated perimeter and is further expected to contribute to changes that will affect land use. Existing studies have ignored land use effects and, instead, assume a monocentric city model. What sets this study apart is that instead of using a monocentric model to test the hypothetical cordon scenarios, the MetroScope model is used to predict changes in economy, demographics, and land use. The MetroScope model is one of only a few models that can assist in forecasting changes in both land use and prices. This study found primary evidence that the implementation of diverse sizes of cordon designs differently affect residential and non-residential land use patterns and trends.

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Rasolofoson, Faraniaina. "A comparative study on the impact of different fluxes in a discontinuous Galerkin scheme for the 2D shallow water equations." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86610.

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Thesis (MSc)--Stellenbosch University, 2014. ENGLISH ABSTRACT: Shallow water equations (SWEs) are a set of hyperbolic partial differential equations that describe the flow below a pressure surface in a fluid. They are widely applicable in the domain of fluid dynamics. To meet the needs of engineers working on the area of fluid dynamics, a method known as spectral/hp element method has been developed which is a scheme that can be used with complicated geometry. The use of discontinuous Galerkin (DG) discretisation permits discontinuity of the numerical solution to exist at inter-element surfaces. In the DG method, the solution within each element is not reconstructed by looking to neighbouring elements, thus the transfer information between elements will be ensured through the numerical fluxes. As a consequence, the accuracy of the method depends largely on the definition of the numerical fluxes. There are many different type of numerical fluxes computed from Riemann solvers. Four of them will be applied here respectively for comparison through a 2D Rossby wave test case. AFRIKAANSE OPSOMMING: Vlakwatervergelykings (SWEs) is ’n stel hiperboliese parsiële differensiaalvergelykings wat die vloei onder ’n oppervlak wat druk op ’n vloeistof uitoefen beskryf. Hulle het wye toepassing op die gebied van vloeidinamika. Om aan die behoeftes van ingenieurs wat werk op die gebied van vloeidinamika te voldoen is ’n metode bekend as die spektraal /hp element metode ontwikkel. Hierdie metode kan gebruik word selfs wanneer die probleem ingewikkelde grenskondisies het. Die Diskontinue Galerkin (DG) diskretisering wat gebruik word laat diskontinuïteit van die numeriese oplossing toe om te bestaan by tussenelement oppervlakke. In die DG metode word die oplossing binne elke element nie gerekonstrueer deur te kyk na die naburige elemente nie. Dus word die oordrag van informasie tussen elemente verseker deur die numeriese stroomterme. Die akkuraatheid van hierdie metode hang dus grootliks af van die definisie van die numeriese stroomterme. Daar is baie verskillende tipe numeriese strometerme wat bereken kan word uit Riemann oplossers. Vier van hulle sal hier gebruik en vergelyk word op ’n 2D Rossby golf toets geval.

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Aboagye-Sarfo, Patrick. "Time series analysis of HIV incidence cases in Ghana : trends, predictions and impact of interventions." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2009. https://ro.ecu.edu.au/theses/1889.

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The HIV/AIDS epidemic is one of the world’s leading causes of death, particularly in sub-Saharan African nations like Ghana, and threatens socio-economic development in many developing countries. In this thesis Ghanaian HIV data, comprising monthly number of serologically confirmed reported new HIV cases since 1996, was subdivided into northern and southern sectors based on the geographical location of the ten administrative regions. Potential bias in the collection is considered given the strategic location of the two specialist teaching hospital, one in each sector, which receive referrals from the regions. Time series modelling was applied to the monthly number of new HIV cases in each sector. Moving average of time series analysis of equal weight was applied to determine the trend for cases of incidence of HIV infection in the northern and southern sectors while Box-Jenkins modelling identification and Holt’s (double) exponential smoothing modelling methods were employed to predict of new incidence of HIV cases for both sectors in respect to sex and age groups. The effectiveness of three existing major interventions was examined using intervention modelling whereas cointegration modelling was used to determine the long-run impact of condom utilisation on the incidence cases of HIV infection. The trend analysis and predictions for the next three years reveal a slow increase in the number of new incidence of HIV cases. Although, various interventions have influenced the number of cases of HIV infection, the magnitude of impact fluctuated and declined with time. The analysis of the long-run impact of condom utilisation, on the reduction of new HIV incidence cases, indicates that new cases of infection will actually increase monthly by factor of 0.4 -0.6 for every 1000 condoms issued. These perplexing results may be because issuing of condoms does not ensure usage.

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Fiorentino, Francesca. "Mathematical models of the impact of rabbit calicivirus disease (RCD) on the European rabbit, Oryctolagus cuniculus, in Australia." Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446810/.

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This thesis relates to the work of building a mathematical model of the impact of Rabbit Calicivirus Disease (RCD) on the European Rabbit, Oryctolagus cuniculus, in Australia. After introducing the general biology of rabbits and the immunology of RCD, we build a time-dependent single site model. We construct a single-site population dynamic model with age structure, seasonal birth rate, density dependent regulation of the population size and climatic variability for various regions of Australia. After investigating suitable parameter ranges, we incorporate the disease dynamics through an indirect transmission model based on two different hypotheses which we call the Strong Juvenile hypothesis and the Weak Juvenile hypothesis. These differ in their assumption about Juvenile immunity to the disease. The ecological impact of both hypotheses is tested for both the single site and multiple site (spatial) models. The disease impact is investigated by varying the disease virulence, i.e. a parameter measuring the "strength" of the virus. Subsequently, a multiple site (spatial) model for the Riverina region is built by using the single-site model as building block. Data from Lake Urana is used to parameterize a seasonal emigration rate from each site. Density dependent immigration is added together with a hazard coefficient which rabbits face when leaving one site and trying to become established in another. Acceptance in a new site is regulated by the population density at the entry site. Several spatial configurations of sites are tested and the spatial dynamics of the disease is investigated. Finally, we construct a model to investigate the long term evolution of the disease virus. We postulate the existence of several strains of the disease and trade-offs between disease characteristics. We allow for mutation of the virus and run the model for two contrasting geographical regions of Australia. We compare the results for the different regions and the different hypotheses regarding Juvenile immunity (the Strong Juvenile hypothesis and the Weak Juvenile hypothesis). It is shown, unexpectedly, that intermediate levels of disease virulence are not selected.

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Bruce, Faikah. "Understanding the impact of an HIV intervention package for adolescents." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85666.

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Thesis (MSc)--Stellenbosch University, 2013. ENGLISH ABSTRACT: Adolescents are regarded as a high risk group in South Africa with the highest human immunodeficiency virus (HIV) incidence occurring in this group. Prevention among adolescents is therefore a key in decreasing the HIV burden. This thesis aims to assist in the design of trials by simulating the potential outcomes of a combination prevention trial in adolescents. We develop a stochastic individual-based model stratified by sex and age. We then use this model to determine the impact of various prevention packages on HIV incidence among adolescents participating in a hypothetical trial over a three year period. The trial that is simulated involves an intervention arm, in which adolescents are offered a choice of a prevention methods (including medical male circumcision (MMC), oral pre-exposure prophylaxis (PrEP) and antiretroviral-based vaginal microbicides (ARV-VM)), and a control arm. We predict that the impact of a full prevention package on HIV incidence would be a 46% per personyear( PPY) (95% CI 45–47%) risk reduction. The combination of MMC and PrEP has a substantial impact on HIV incidence in males, with a 51% PPY (95% CI 49–53%) relative risk of HIV infection. Offering women the choice of PrEP, a microbicide gel or a microbicide in the form of a vaginal ring would be less effective, with a 57% PPY (95% CI 56–58%) relative risk of HIV acquisition. This is not substantially different from the relative risk estimated when the vaginal ring alone is offered, as the ring is assumed to be the most accept able of the three prevention methods. We determine a sample size requirement of approximately 1013 in each arm of a trial would achieve 80% power to detect a statistically significant reduction in HIV risk. We find that the relative risk is sensitive to the assumed degree of correlation between condom use and the acceptability of the prevention method. We also find that the most efficient trial design may be to offer both MMC and PrEP to males but to offer only a microbicide ring to females. Further work is required to better understand the processes by which adolescent prevention method choices are made. AFRIKAANSE OPSOMMING: Adolessente word beskou as ‘n hoe risiko groep in Suid Afrika, met die hoogste menslike immuniteitsgebrekvirus (MIV) insidensie in hierdie groep. Voorkoming van MIV onder adolessente is daarom noodsaaklik om die MIV las te verminder. Die doel van hierdie tesis is om te help met die ontwerp van studies deur die moontlike uitkomste van ‘n kombinasie-voorkoming studie in adolessente te simuleer. Ons het ‘n stogastiese individu-gebaseerde model, gestratifiseer met betrekking tot seks en ouderdom, ontwikkel. Ons het toe die model gebruik om die impak van ‘n verskeinheid van voorkomingspakette op MIV insidensie onder adolessente wat deelneem aan ‘n hipotetiese proef oor ‘n drie jaar periode, te bepaal. Die proef wat gesimuleer word behels a intervensie groep, waarin die jong volwassenes ‘n keuse van voorbehoedings metodes (insluitende mediese manlike besnydenis (MMB), pre-blootstelling profilakse (PrBP) en anti-retrovirale vaginale mikrobisiedes (ARV-VM)) aangebied word, en ‘n kontrole groep. Ons voorspel dat die impak van ‘n volle voorkomingspaket op MIV insidensie ‘n 46% per persoon-jaar (PPJ) (95% VI 47–47%) risiko vermindering sal wees. Die kombinasie van MMB en PrBP het ‘n substansiele impak op MIV insidensie onder mans, met ‘n relatiewe risiko van MIV infeksie van 51% PPJ (95% VI 49–53%). Om die keuse van PrBP, ‘n mikrobisiede gel of ‘n mikrobisiede in die vorm van ‘n vaginale ring aan vrouens te bied, is minder effektief, met ‘n relatiewe risiko van MIV infeksie van 57% PPJ (95% VI 56%–58%). Hierdie verskil nie substansieel van die beraamde relatiewe risiko in die geval waar slegs die vaginale ring gebied word nie, aangesien daar aanvaar word dat die ring die mees aanvaarde van die drie voorkomingsmetodes is. Ons het bepaal dat ‘n steekproef van ongeveer 1013 individue in elke arm van die proef nodig is om ‘n 80% kans te he om ‘n statisties betekenisvolle afname in MIV-risiko te bespeur. Ons vind dat die relatiewe risiko sensitief is tot die aanvaarde graad van die korrelasies tussen kondoom-gebruik en die aanvaarding van die voorkomings metodes. Ons het ook gevind dat dit mag wees dat die mees doeltreffende proef ontwerp is om beide MMB en PrBP vir mans en slegs ‘n mikrobisiede ring vir vrouens te bied. Verdere werk word benodig om die prosesse waarby jong volwassenes keuses maak oor voorkomingsmetodes te verstaan.

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Healy, William M. "Modeling the impact of a liquid droplet on a solid surface." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16737.

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Coyne, Alice Elizabeth. "The impact of estimation frequency on Value at Risk (VaR) and Expected Shortfall (ES) forecasts: an empirical study on conditional extreme value models." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/32558.

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This study investigates extreme market events which occur in the tails of a distribution. The extreme events occur with a very low probability, but with significant consequences, which is what makes them of interest. In this study 20 years of data from both the S&P 500 and the JSE All Share index have been used. An extreme value approach has been taken to quantify the risks associated with extreme market events. To achieve this a two phased process is used to calculated the Value at Risk and Expected Shortfall. The first phase involved running the daily returns through the GARCH model, and then extracting the residuals. The second phase involves using the Block Maxima Method, or Peaks over Threshold method to fit the residuals to the Generalized Extreme Value Distribution or the Generalized Pareto Distribution. Finally, the impact of estimation frequency is considered for each of the models. In conclusion, taking an extreme value approach to provide a statistically sound method to calculate risk, even when the parameters of the model are updated less frequently, this is preferable to simpler models where the parameter estimates are updated daily.

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Chan, Shu-ning, and 陳樹寧. "Impact of river training on the hydraulics and sediment transport of Shenzhen River." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43572194.

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Njagarah, Hatson John Boscoh. "Modelling the role of amelioration and drug lords on drug epidemics and the impact of substance abuse on the dynamics of HIV/AIDS." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17935.

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Thesis (MSc)--Stellenbosch University, 2011. ENGLISH ABSTRACT: Substance abuse is an imminent danger on the health of both substance users and nonusers. In general, abuse of psychoactive substances is associated with high risk behaviour, mortality and morbidity. The drug use cycle involves inextricably intertwined variants such as production, trading and usage of both licit and illicit addictive substances. The dynamics of substance use involve initiation, addiction, rehabilitation/treatment and quitting/ recovery. In response to supply and abuse of monster drugs, control strategies such as law enforcement and rehabilitation have been stepped up to reduce access to drugs by targeting drug kingpins and harm reduction respectively. In this thesis, we model the factors affecting the prevalence of substance abuse, the effect of drug lords on the prevalence of substance abuse, and the impact of substance abuse on the prevalence of HIV/AIDS. We formulate mathematical models based on systems of autonomous differential equations describing the dynamics of the sub- populations involved in the drug using cycle. We examine the effects of amelioration, rehabilitation/treatment and re- initiation on the prevalence of substance abuse. Our results suggest that, recruitment into rehabilitation and amelioration in the presence of quitting for light users reduce the prevalence of substance abuse; re-initiation and amelioration without quitting for light users increase the prevalence of substance abuse. Our assessment of the impact of drug lords and the effect of law enforcement on drug epidemics shows that, the presence of drug lords seriously constraints the efforts to reduce substance abuse since they increase access to drugs. However, law enforcement if stepped up in response to the population of drug lords, greatly reduces the prevalence of substance abuse. Given the associated influence of drugs on high risky behaviour, as a cofactor for sexually transmitted infections, we assess the influence of substance abuse on the prevalence of Human Immunodeficiency Virus (HIV). Our results show that dissemination of information regarding HIV and drug use reduces HIV prevalence whereas, there is faster spread of the epidemic and high prevalence with increased sexual contact. AFRIKAANSE OPSOMMING: Dwelmmisbruik is ’n dreigende gevaar vir die gesondheid van beide dwelm gebruikers en nie-gebruikers. In die algemeen, word die misbruik van psigoaktiewe dwelms verbind met hoë risiko gedrag, mortaliteit en morbiditeit. Die dwelmgebruikskringloop behels onlosmaaklik vervlegde variante soos vervaardiging, handel en gebruik van beide wettige en onwettige verslawende middels. Die dinamika van dwelms behels aanvang, verslawing, rehabilitasie/ behandeling en staking/herstel. In reaksie op die misbruik en verskaffing van monster dwelms, is beheer strategieë soos wetstoepassing en rehabilitasie verskerp, om die toegang tot dwelms te verminder, deur onderskeidelik te fokus op dwelmspilfigure en skadebeperking. Die belangrikste doel van hierdie verhandeling is om die faktore te modelleer wat die voorkoms van dwelmmisbruik beïnvloed, die uitwerking van dwelmbase op die voorkoms van dwelmmisbruik, en die trefkrag van dwelmmisbruik op die voorkoms van MIV / VIGS. Ons formuleer wiskundige modelle gegrond op stelsels van outonome differensiaalvergelykings, wat die dinamika beskryf van die sub-bevolkinge wat in die dwelmgebruikskringloop betrokke is. Ons ondersoek die effekte van verbetering, rehabilitasie/behandeling en heraanvang op die voorkoms van dwelmmisbruik. Ons resultate dui dat, werwing tot rehabilitasie en verbetering in die teenwoordigheid van stakende tydelike verbruikers, die voorkoms van dwelmmisbruik verminder; heraanvang en verbetering sonder dat tydelike verbruikers staak, verhoog die voorkoms van dwelmmisbruik. Ons raming van die invloed van dwelmbase en die uitwerking van wetstoepassing op dwelm-epidemies toon dat, die teenwoordigheid van dwelmbase belemmer grotendeels die pogings om dwelmmisbruik te verminder, aangesien hulle toegang tot dwelms verhoog. Nietemin, as die wetstoepassing verskerp word in reaksie op die dwelmbaasbevolking, word die voorkoms van dwelmmisbruik aansienlik verminder. Gegewe die gepaardgaande invloed van dwelms op hoë risiko gedrag as ’n kofaktor vir seksueel oordraagbare infeksies, beraam ons die invloed van dwelmmisbruik op die voorkoms van die Menslike Immunogebreksvirus (MIV). Ons resultate toon dat inligtingverspreiding rakende MIV en dwelmgebruik, MIV-voorkoms verlaag, terwyl daar ’n vinniger verspreiding van die epidemie en hoë voorkoms is, met verhoogde seksuele kontak.

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Prestes, Manoel Fernando Biagioni 1963. "Dispersão de material impactante em meio aquático = modelo matemático, aproximação numérica e simulação computacional - Lagoa do Taquaral, Campinas, SP." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307272.

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Orientador: João Frederico da Costa Azevedo Meyer Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica Made available in DSpace on 2018-08-19T09:35:38Z (GMT). No. of bitstreams: 1 Prestes_ManoelFernandoBiagioni_M.pdf: 6775504 bytes, checksum: 58bb4307baf12ee09b0deeae72c3c8c9 (MD5) Previous issue date: 2011 Resumo Este estudo visa descrever a evolução de material impactante na Lagoa do Taquaral, tendo sido inclusive apresentada inicialmente, uma descrição desse meio aquático, enfatizando-se os aspectos histórico, climático e geomorfológico nesta contextualização. Para a modelagem do fenômeno evolutivo utilizou-se a equação diferencial parcial clássica de Difusão-Advecção, tradicionalmente empregada na modelagem de fenômenos deste gênero. A discretização espacial do modelo caracteriza-se pelo uso do Método das Diferenças Finitas, sendo que a discretização temporal foi obtida através do Método de Crank-Nicolson. Quanto aos resultados numérico-computacionais obtidos, podemos destacar as três situações-cenário consideradas, conforme a direção predominante dos ventos adotada, com vistas a estabelecer adequados mecanismos de monitoramento, da dispersão de material impactante no meio aquático. Outrossim buscamos, neste trabalho, ferramentas capazes de propiciar estratégias a serem adotadas em políticas de prevenção e contingência, para os problemas gerados pela intervenção antrópica na micro-região em estudo. Ensejamos, ainda, estimular o poder público quanto instituição, a promover um planejamento e manuseio mais adequado do acervo ambiental Abstract: This work has the purpose of describing the evolutionary behavior of a pollutant in a certain domain, and we have adopted the Taquaral lake as the objective example, which we initially describe in its historic, climatic and geomorphological aspects. In order to mathematically model this situation, we used a classical diffusive-advective partial differential equation. The spatial discretization is undertaken with the use of Second order central Finite Differences, while the discretization in time is done with the Crank-Nicolson Method. Three scenarios were considered, according to predominant wind directions, adopted for the numerical essays. The purpose of this was to create effective computational tools for monitoring pollutant spills and discharges in the aquatic medium. In other words, this work also intends to make available a numerical (and mathematical, as well as computational) tool for evaluating preventive and contingency policies for those polluting problems created by anthropic urban activities, besides stimulating a more precise environmental planning in this kind of situation Mestrado Matemática Universitária Mestre em Matemática Universitária

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Corley, Courtney D. "Modeling the Impact and Intervention of a Sexually Transmitted Disease: Human Papilloma Virus." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5289/.

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Many human papilloma virus (HPV) types are sexually transmitted and HPV DNA types 16, 18, 31, and 45 account for more than 75% if all cervical dysplasia. Candidate vaccines are successfully completing US Federal Drug Agency (FDA) phase III testing and several drug companies are in licensing arbitration. Once this vaccine become available it is unlikely that 100% vaccination coverage will be probable; hence, the need for vaccination strategies that will have the greatest reduction on the endemic prevalence of HPV. This thesis introduces two discrete-time models for evaluating the effect of demographic-biased vaccination strategies: one model incorporates temporal demographics (i.e., age) in population compartments; the other non-temporal demographics (i.e., race, ethnicity). Also presented is an intuitive Web-based interface that was developed to allow the user to evaluate the effects on prevalence of a demographic-biased intervention by tailoring the model parameters to specific demographics and geographical region.

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Bagntasarian, Anachit. "The impact of CEO compensation, analysts' characteristics, earnings management and country governability on analysts' earnings forecasts." Thesis, University of Sussex, 2018. http://sro.sussex.ac.uk/id/eprint/76656/.

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This thesis examines the impact of CEO compensation, analysts' characteristics, earnings management and country governability on the accuracy of analysts' earnings forecasts. In summary, the thesis includes the following chapters: Firstly, Chapter 2 examines the interplay between CEO compensation and analysts' forecast errors over different forecasting horizons. A unique analyst-level sample for U.S. firms covering the period between 1992 and 2015 has been employed. Evidence obtained from this analysis suggests that CEO compensation, measured by various forms such as restricted stock holdings and stock ownership would correct for optimism in analysts' earnings forecasts, whereas CEO bonus and sensitivity to changes in firm's value would exacerbate analysts' optimism. Results also show that CEO compensation would augment the effect of earnings management on analysts' forecasts with CEO bonus being of importance. The findings of this chapter also indicate that analysts' characteristics and regulation can affect earnings forecasts. Next, Chapter 3 investigates the effect of governance on analysts' earnings forecasts. By employing a comprehensive dataset of 911 U.S. firms for the period 2000 – 2014, this chapter demonstrates a strong positive association between the government effectiveness and analysts' earnings forecasts. We extend this analysis employing corporate governance variables such as CEO equity incentives and CEO power, whilst a possible cross-term association between governability and the former has also been examined. This chapter explores further the effects of earnings management on analysts' forecasts accuracy documenting a negative impact of the former on the latter. Lastly, underlying causality strands and endogeneity issues are addressed opting for a flexible panel VAR model. Finally, Chapter 4 presents evidence of the effects of corruption on the accuracy of analysts' forecasts. Using a global sample, this chapter reveals that analysts face greater difficulty in forecasting earnings in advanced and emerging countries due to the detrimental effect of corruption. Interestingly, findings suggest that for firms located in developing countries, corruption enhances analysts' accuracy. This chapter also shows that the effect of earnings manipulation on the accuracy of forecasts is aggravated in the presence of corruption, whilst greater country freedom would enhance analysts' accuracy when corruption is present.

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Abdolmaleki, Kourosh. "Modelling of wave impact on offshore structures." University of Western Australia. School of Mechanical Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0055.

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[Truncated abstract] The hydrodynamics of wave impact on offshore structures is not well understood. Wave impacts often involve large deformations of water free-surface. Therefore, a wave impact problem is usually combined with a free-surface problem. The complexity is expanded when the body exposed to a wave impact is allowed to move. The nonlinear interactions between a moving body and fluid is a complicated process that has been a dilemma in the engineering design of offshore and coastal structures for a long time. This thesis used experimental and numerical means to develop further understanding of the wave impact problems as well as to create a numerical tool suitable for simulation of such problems. The study included the consideration of moving boundaries in order to include the coupled interactions of the body and fluid. The thesis is organized into two experimental and numerical parts. There is a lack of benchmarking experimental data for studying fluid-structure interactions with moving boundaries. In the experimental part of this research, novel experiments were, therefore, designed and performed that were useful for validation of the numerical developments. By considering a dynamical system with only one degree of freedom, the complexity of the experiments performed was minimal. The setup included a plate that was attached to the bottom of a flume via a hinge and tethered by two springs from the top one at each side. The experiments modelled fluid-structure interactions in three subsets. The first subset studied a highly nonlinear decay test, which resembled a harsh wave impact (or slam) incident. The second subset included waves overtopping on the vertically restrained plate. In the third subset, the plate was free to oscillate and was excited by the same waves. The wave overtopping the plate resembled the physics of the green water on fixed and moving structures. An analytical solution based on linear potential theory was provided for comparison with experimental results. ... In simulation of the nonlinear decay test, the SPH results captured the frequency variation in plate oscillations, which indicated that the radiation forces (added mass and damping forces) were calculated satisfactorily. In simulation of the nonlinear waves, the waves progressed in the flume similar to the physical experiments and the total energy of the system was conserved with an error of 0.025% of the total initial energy. The wave-plate interactions were successfully modelled by SPH. The simulations included wave run-up and shipping of water for fixed and oscillating plate cases. The effects of the plate oscillations on the flow regime are also discussed in detail. The combination of experimental and numerical investigation provided further understanding of wave impact problems. The novel design of the experiments extended the study to moving boundaries in small scale. The use of SPH eliminated the difficulties of dealing with free-surface problems so that the focus of study could be placed on the impact forces on fixed and moving bodies.

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Lenane, Ian Joseph. "An investigation of mathematical models for spray droplet spreading on plant leaves with new results applicable to uniform, horizontal, solid surfaces." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/204179/1/Ian_Lenane_Thesis.pdf.

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This thesis presents a literature review of mathematical models developed to simulate the spreading of agrichemical spray droplets impacting on plant leaf surfaces. New results are derived to predict how far droplets will spread when deposited or sprayed perpendicularly onto a dry, uniform, horizontal, solid surface. The first part of the new research provides equations to predict the extent a sessile droplet will spread on these surfaces as well as its itemized energy budget. The second part examines scaling law formulae to predict the maximum spreading factor for droplets impacting the solid at non-zero velocities.

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Dissanayake, I. A. J. K. "The impact of water deficit on the growth and yield performance of sesame (Sesamum indicum l.): Analysis through mathematical modelling." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/112360/1/Jinendra%20Kumari%20Dissanayake_Imaduwa%20Arachchige_Thesis.pdf.

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This thesis investigated the effect of drought stress on agronomical, and physiological characteristics of sesame plants during growth and development, and analysed such responses using Fuzzy set theory (FST) and Artificial Neural Networks (ANN), two mathematical modeling tools. Subjected to cultivar and developmental stages exposed to drought, tested sesame cultivar/s expressed versatile morphological adaptations and adjusted leaf osmotic potential as a drought tolerant mechanism to survive drought conditions. The thesis proposed FST models with various membership functions to describe germination, growth and yield responses of sesame cultivars, and ANN models to forecast sesame yield under given climatic conditions.

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Kumar, Arun. "Ground control ramifications and economic impact of retreat mining on room and pillar coal mines." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49815.

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As the coal reserves at shallow depths become exhausted companies have to develop deeper deposits and increase percentage extraction to maintain production levels. Total extraction for room and pillar mines can only be achieved by pillar extraction. The unsupported roof increases during pillar extraction and hence the cost of ground control also increases. Nevertheless, pillar extraction where possible has many potential advantages such as decreased operating cost, increased utilization of reserves, and extended life of the mine. There are several variables such as depth, mining height, rock strength, mining geometry, roof and floor conditions, and retreat mining methods, which affect pillar extraction cost. Cost components of pillar extraction are classified as direct, indirect, fixed, and subsidence compensation costs. A discounted cash flow pillar extraction cost simulator has been developed and used to compute total pillar extraction cost for a variety of conditions and to explore the possibilities of optimizing ground control and retreat mining techniques to maximize extraction ratio. The computer program computes the safe and optimum pillar dimensions and determines the suitable pillar extraction method for the computed pillar width. Pillar extraction cost components are generated and totalled using the net present value method by the simulator. The total extraction cost simulator evaluates the potential advantages of pillar extraction and tests individual variables for sensitivity to changes in other variables attributable to ground control and pillar extraction techniques. Cost of pillar extraction per ton of coal versus depth is presented in the form of a simple nomogram by the simulator. The simulator can be used to determine the economic feasibility of pillar extraction at a particular depth, geologic and mining environment when the market price of mined coal is known. Ph. D. incomplete_metadata

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Khalil, Adil. "Processing of laser speckle contrast images : study of mathematical models and use of nonlinear analyses to investigate the impact of aging on microvascular blood flow." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0006/document.

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Le vieillissement est un facteur de risque des maladies cardiovasculaires. Il est associé à des altérations fonctionnelles et structurelles du système vasculaire.Une étude approfondie du processus de vieillissement et le développement de systèmes d’imagerie et des traitements de données associés deviennent donc une priorité. Par l’analyse d’images de contraste par speckle laser (LSCI), l’objectif de cette thèse est d’étudier l’influence de l’âge sur la micro circulation.Pour ce faire, des données de LSCI ont été acquises sur l’avant-bras de sujets sains jeunes et âgés. A partir de modèles mathématiques, nous avons déterminé la vitesse des érythrocytes de la micro circulation chez les deux groupes de sujets. Par ailleurs, nous avons également mené une étude de la complexité de séries temporelles d’ LSCI s’appuyant sur des mesures d’entropie multi échelle. Nos résultats montrent que : 1) le groupe de sujets plus âgés présente des valeurs de vitesse des globules rouges significativement plus élevées que celles des sujets jeunes à l’hyperémie réactive post-occlusive; 2) les fluctuations des séries temporelles de LSCI dans le groupe des sujets jeunes ont une complexité supérieure à celles du groupe de sujets âgés. Ces modifications observées sur la micro circulation pourraient être attribuées à des modifications du système vasculaire dans son ensemble. La compréhension de ces altérations pourrait conduire à de nouvelles perspectives en matière de prévention et de traitement des pathologies liées à l’âge Aging is a primary risk factor for cardiovascular diseases. It is associated with functional and structural alterations in the vascular system. Therefore, a deep study of the aging process and the development of imaging systems and associated processing become of the utmost importance. By processing laser speckle contrast images (LSCI), this PhD work aims at studying the influence of age on microcirculation. In our work, LSCI data were acquired from the skin forearm of healthy subjects, subdivided into two age groups (younger and older). From mathematical models, we determined red blood cells velocity in microcirculation in the two groups of subjects. Moreover, we applied multiscale entropy-based algorithms to LSCI time series in order to study the complexity of microvascular signals. Our main findings are: 1) the older group has significantly higher velocity values than the younger group at post-occlusive reactive hyperaemia; 2) LSCI fluctuations in the younger group have significantly higher complexity than those of the older group. Age-related changes in skin microcirculation can be attributed to alterations in the vascular system as a whole. Understanding these changes in the microcirculatory system may give new insights for prevention and treatment of age-related diseases

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Butler, Ailsa R. "Measles, mumps and rubella (MMR) immunisation programmes in Europe : analyses of the impact on the incidence of measles based on mathematical models of viral transmission dynamics." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249240.

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Niklewski, Jacek. "Multivariate GARCH and portfolio optimisation : a comparative study of the impact of applying alternative covariance methodologies." Thesis, Coventry University, 2014. http://curve.coventry.ac.uk/open/items/a8d7bf49-198d-49f2-9894-12e22ce2d7f1/1.

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This thesis investigates the impact of applying different covariance modelling techniques on the efficiency of asset portfolio performance. The scope of this thesis is limited to the exploration of theoretical aspects of portfolio optimisation rather than developing a useful tool for portfolio managers. Future work may entail taking the results from this work further and producing a more practical tool from a fund management perspective. The contributions made by this thesis to the knowledge of the subject are that it extends literature by applying a number of different covariance models to a unique dataset that focuses on the 2007 global financial crisis. The thesis also contributes to the literature as the methodology applied also enables a distinction to be made in respect to developed and emerging/frontier regional markets. This has resulted in the following findings: First, it identifies the impact of the 2007–2009 financial crisis on time-varying correlations and volatilities as measured by the dynamic conditional correlation model (Engle 2002). This is examined from the perspective of a United States (US) investor given that the crisis had its origin in the US market. Prima facie evidence is found that economic structural adjustment has resulted in long-term increases in the correlation between the US and other markets. In addition, the magnitude of the increase in correlation is found to be greater in respect to emerging/frontier markets than in respect to developed markets. Second, the long-term impact of the 2007–2009 financial crisis on time-varying correlations and volatilities is further examined by comparing estimates produced by different covariance models. The selected time-varying models (DCC, copula DCC, GO-GARCH: MM, ICA, NLS, ML; EWMA and SMA) produce statistically significantly different correlation and volatility estimates. This finding has potential implication for the estimation of efficient portfolios. Third, the different estimates derived using the selected covariance models are found to have a significant impact on the calculated weights and turnovers of efficient portfolios. Interestingly, however, there was no significant difference between their respective returns. This is the main finding of the thesis, which has potentially very important implications for portfolio management.

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Hove, Progress. "The impact of technological marketing on Porter's competitive forces model and SMEs' performance." Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/d1007120.

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It is commonly understood that the adoption and development of technological marketing capabilities by firms provides them with immense opportunities to transform their business practices and strategies, so as to strategically position themselves in the market and enhance firm performance. Nevertheless, little attention has, thus far, been given to the empirical investigation of the impact of adopting and developing the technological marketing on Porter‟s five competitive forces and firm performance of SMEs. The principal objective of this study was to fill this void by investigating the influence of the technological marketing on Porter‟s five competitive forces model (industry structure) of SMEs in the Buffalo City Metropolitan Municipality. Secondarily, the study sought to determine the influence of technological marketing capability on firm performance of SMEs in the Buffalo City Metropolitan Municipality; in order to ascertain whether or not the competitiveness of SMEs impacts on their firm performance; to determine whether or not SMEs adopt new and advanced technological capabilities when marketing their products/services and to examine whether or not SMEs adopt new and advanced technological capabilities in order to enhance their performance. The study employs a quantitative method in data collection. Sample data from 211 SME owners/managers in the retail and manufacturing sectors of Buffalo City Metropolitan Municipality was collected for the final data analysis of this project. The sample data was analysed by performing a Confirmatory Factor Analysis (CFA) and Structural Equation Modeling (SEM) using AMOS 7 Statistical Analysis software. The principal finding of this study reveals that technological marketing has no significant impact on Porter‟s five forces. In addition, the results showed that technological marketing capability has a positive and significant influence on firm performance. The findings also revealed that SMEs adopt new and advanced technologies when marketing their products and services. The conclusions and implications of the research findings are provided and recommendations are suggested. The researcher recommended non technological strategies for improving SMEs‟ competitiveness and the following technological strategies to boost performance: creating a customer-centric e-commerce strategy, embracing outsourcing, joining e-business community and integrating information management into new marketing technologies. Strategies were also recommended to the government as the policy maker. These include introducing e-business finance arrangement, marketing hubs for SMEs and promoting synergies between technology vendor companies and the small enterprises. The study tried to address marketing technologies‟ policy deficiencies on the side of both SMEs and the government.

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Laws, Nathan. "A Parabolic Equation Analysis of the Underwater Noise Radiated by Impact Pile Driving." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1083.

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Impact pile driving can produce extremely high underwater sound levels, which are of increasing environmental concern due to their deleterious effects on marine wildlife. Prediction of underwater sound levels is important to the assessment and mitigation of the environmental impacts caused by pile driving. Current prediction methods are limited and do not account for the dynamic pile driving source, inhomogeneities in bathymetry and sediment, or physics-based sound wave propagation. In this thesis, a computational model is presented that analyzes and predicts the underwater noise radiated by pile driving and is suitable for shallow, inhomogeneous environments and long propagation ranges. The computational model uses dynamic source models from recent developments in the technical literature. Pile source models are coupled to a broadband application of the range-dependent acoustic model (RAMPE), a standard parabolic equation (PE) propagation code capable of modeling wave propagation through complex, range dependent environments. Simulation results are shown to be in good agreement with several observations of pile driving operations in the Columbia River between Portland, Oregon and Vancouver, Washington. The model is further applied to extend sound level predictions over the entire river and study the effects of sediment and bathymetry on the underwater sound levels present in the environment.

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Lavor, Daniel Campos. "AvaliaÃÃo de impacto e formulaÃÃo de modelo para polÃtica educacional." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10727.

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nÃo hÃ Em virtude da importÃncia atribuÃda Ã educaÃÃo como um dos maiores condutores do crescimento, e Ã grande variaÃÃo de impactos decorrentes das diferentes polÃticas educacionais, a educaÃÃo bÃsica mantem-se um tema ativo na agenda de pesquisadores, na busca do desenvolvimento de pesquisas teÃricas e empÃricas, em alternativas abordagens de tratamento. A CiÃncia EconÃmica tem contribuÃdo significativamente com novas abordagens metodolÃgicas na relaÃÃo entre as ideias e a implementaÃÃo de anÃlises empÃricas, atravÃs do uso intensivo de modelos matemÃticos explicativos. Inspirado nisso, este trabalho espera contribuir para o debate atravÃs da formulaÃÃo de um modelo matemÃtico que busca solucionar alguns impasses incorridos nas anÃlises empÃricas. Tal modelo foi desenvolvido com base em pesquisas especializadas, que identificaram novos fatores explicativos da qualidade da educaÃÃo, corroboradas por duas anÃlises empÃricas. Inicialmente, investigou-se os fatores escolares relacionados Ã diferenÃa de desempenho das escolas pÃblicas brasileiras, medida atravÃs do Ãndice de Theil-L, a partir dos resultados observados na Prova Brasil de 2011. Em seguida, realizou-se uma avaliaÃÃo de impacto de uma polÃtica educacional especÃfica, para a qual se utilizou o mÃtodo de Controle SintÃtico, constatando a efetividade da polÃtica. A partir disso, hÃ a expectativa de que o modelo desenvolvido auxilie na discussÃo dos mecanismos que possibilitam polÃticas de educaÃÃo de maior impacto. Due to the worldwide recognition of the importance attached to education as a major engine of growth, and the wide range of impacts carried out by the different educational policies, investigating basic education has been kept active on the agenda of researchers in the pursuit of the development of theoretical and empirical research, as well as alternative treatment approaches. Economic Science has contributed significantly to new methodological approaches in the relationship between ideas and implementation of empirical analysis, through extensive use of mathematical explanatory models. Inspired by this, this paper hopes to contribute to the debate by formulating a mathematical model that seeks to solve some deadlocks incurred in several empirical analyzes. This model was empirically applied through two distinct approaches, which identified new factors explaining the quality of education. Firstly, it was investigated the schooling factors that dictate the differences in the scores of the âProva Brazil of 2011â for public schools based upon the Theil-L index. Secondly, an impact evaluation of a specific educational policy was performed through a Synthetic Control Method, which pointed for the effectiveness of such policy. It is expected that the developed model contributes to the debate about alternative impact mechanisms caused by education policies.

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Gu, Chao. "Création d'un modèle inductifs de croissance de clusters industriels à flux optimisés, pour réduire leur impact sur l'environnement." Thesis, Le Havre, 2015. http://www.theses.fr/2015LEHA0013/document.

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L’écologie industrielle a pour objectif de résoudre les questions liées à l'utilisation des ressources technologiques dans les sociétés, dans le but d'ajouter à la partie des connaissances nécessaires pour commencer à évaluer les problèmes de qualité liés à l'environnement et les questions de disponibilité des ressources. Le concept d’écologie industrielle peut être réalisé et pratiqué à travers d’établissement des parcs éco-industriels. Un parc éco-industriel est une communauté de fabrication et de service des entreprises situées ensemble sur une propriété commune. Les membres cherchent la performance environnementale, économique et sociale accrue grâce à la collaboration dans la gestion des questions environnementales et de ressource. L’objectif principal de la thèse est de créer des modèles mathématiques d’optimisation pour maximiser des flux des échanges dans un parc éco-industriel et pour réduire les impacts négatifs des industries sur l’environnement. Les sept parcs éco-industriels symboliques et emblématiques dans le monde ont été étudiés durant la thèse pour obtenir une vision pratique de la problématique et pour acquérir les informations du développement des éco-parcs de la réalité. Les dix outils informatiques et les modèles d’optimisation pour les parcs éco-industriels ont été étudiés. Trois modélisations d’optimisation sont proposées avec les simulations numériques effectuées Industrial ecology aims to resolve issues related to the use of technological resources in societies in order to add to the party the knowledge to begin to assess quality issues related to the environment and resource availability issues. The concept of industrial ecology can be realized and practiced through the establishment of eco-industrial parks. An eco-industrial park is a manufacturing community and service businesses located together on a common property. Members seek environmental performance, increased economic and social through collaboration in managing environmental and resource. The main aim of this thesis is to create mathematical optimization models to maximize trade flows in an eco-industrial park and to reduce the negative impacts of industry on the environment. The seven symbolic eco-industrial parks have been studied in this thesis in order to get a practical view of the issues and to acquire information from the development of eco-parks in reality. The numerical tools and optimization models for eco-industrial parks were studied. Three optimization models have been proposed with numerical simulations in this thesis

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Romaniw, Yuriy. "An activity based method for sustainable manufacturing modeling and assessments in SysML." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34717.

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Traditionally, environmental impacts of man made products have been determined by performing a life cycle assessment (LCA) on the product. As the name implies, LCA is usually covers the entire life of the product in a so-called "cradle-to-grave" assessment. In determining environmental impacts over the whole product life, LCA's are reasonably adequate. However, in providing detailed impacts on a particular phase of life, LCA's are lacking. Detailed assessments are important because very few stakeholders have influence over a product during all phases of life. Stakeholders need detailed impact assessments in their particular phase of life. More detailed assessments give stakeholders more information that can be used for better environmental management (EM) and more environmentally benign operations. In many LCA's, the manufacturing phase of life has been over-generalized and over-simplified because of its relatively small environmental impact, as compared to other phases of life. Nevertheless, certain stakeholders, such as manufacturing companies, need detailed impact information for the manufacturing phase of life so that they can create a more sustainable manufacturing process. Most traditional LCA's use a case-based approach, which was deemed to be inadequate. For these LCA's, the information provided for each case is often quite detailed and specific. However, this makes the assessment less flexible, limiting the quality of the assessment to the degree that the current scenario matches the existing cases. In order to make a more user-specific assessment, a model-based approach was used. To give the model flexibility, a parametric model was created based on mathematical equations that represent various parts of the manufacturing process. To give the model structure, an activity-based costing (ABC) approach was used. Using the ABC structure, the manufacturing process was broken down into activities, each of which was characterized by mathematical models. Large models would be difficult to construct and simulate by hand, so a model was built with the aid of a computer. The modeling language SysML (Systems Modeling Language) was used to create an object-oriented model of the manufacturing process, using the ABC structure. SysML defines overall properties and behaviors of the various elements in the model, while the plug-in tool ParaMagic was used to execute the model via a Mathematica Solver. The model computes carbon dioxide emissions, energy consumption, and waste mass generation for a particular manufacturing scenario. The goal of the model was to quantify environmental impact factors in order to aid manufacturing stakeholders in EM. The overall goal of the research was to determine whether an activity-based, object-oriented model was a valid approach, and whether the computer-aided tools adequately implemented this approach. Findings show that SysML is capable of modeling large and complex systems. However, due to some limitations of Paramagic, only some of SysML's capabilities were utilized. Nevertheless, Paramagic is capable of extracting information out of a manufacturing model built in SysML, and solving parametric relations in Mathematica in a timely manner. Timely solutions of complex models are critical for stakeholders keeping a competitive edge.

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Schmid, Neset Tina-Simone. "Environmental imprint of human food consumption : Linköping, Sweden 1870-2000 /." Linköping : Department of Water and Environmental Studies, Linköping University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-3592.

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Siddique, Sharif Rayhan. "Development of policies to ameliorate the environmental impact of cars in Perth City, using the results of a stated preference survey and air pollution modelling." University of Western Australia. Faculty of Business, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0165.

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[Truncated abstract] Air pollution is increasingly perceived to be a serious intangible threat to humanity, with air quality continuing to deteriorate in most urban areas. The main sources of inner city pollution are motor vehicles, which generate emissions from the tail pipe as well as by evaporation. These contain toxic gaseous components which have adverse health effects. The major components are carbon monoxide (CO), nitrogen dioxide (NO2), nitric oxide (NO), sulphur dioxide (SO2), particulates (PM10), and volatile organic compounds (VOC). CO and oxides of nitrogen (NOx) are major emissions from cars. This study focuses on pollutant concentration in Perth city and has sought to develop measures to improve air quality. To estimate concentrations, the study develops air pollution models for CO and NOx; on the basis of the model estimates, effective policy is devised to improve the air quality by managing travel to the city. Two peaks, due to traffic, are observed in hourly CO and NOx concentrations. Unlike traffic, however, the morning peak does not reach the level of the afternoon peak. The reasons for this divergence are assessed and quantified. Separate causal models of hourly concentrations of CO and NOx explain their fluctuations accurately. They take account of the complex effects of the urban street canyon and winds in the city. The angle of incidence of the wind has significant impact on pollution level; a wind flow from the south-west increases pollution and wind from the north-east decreases it. The models have been shown to be equivalent to engineering and scientific models in estimating emission rate in the context of street canyons. However the study models are much more precise in the Perth context. ... The models are used to calculate the marginal effects for all attributes and elasticity for fuel price. In almost all attributes the non-work group is more responsive than the work group. Finally, the SP model results are integrated into an econometric model for the purpose of prediction. The travel behaviour prediction is used to estimate the policy impact on air quality. The benefit from the air quality improvement is reported in terms of life saved. The estimated relationships between probability of death and air pollution determines the number of lives that could be saved under various policy scenarios. A ratio of benefits to the financial and perceived sacrifices by drivers is calculated to compare the effectiveness of the suggested policies. A car size charge policy was found to be the most cost effective measure to ameliorate the environmental impact of cars in Perth, with a morning peak entry time charge being almost as cost effective. The study demonstrates the need for appropriate modelling of air pollution and travel behaviour. It brings together analytical methods at three levels of causality, vehicle to air pollution, charge to travel response, and air pollution to health.

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Winship, Arliss J. "Estimating the impact of bycatch and calculating bycatch limits to achieve conservation objectives as applied to harbour porpoise in the North Sea." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/715.

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Bopf, Tara-Louise. "Mathematical modelling of worker interactions and the impact on workplace safety." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/104384/1/Tara-Louise_Bopf_Thesis.pdf.

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This research involves applying mathematical modelling techniques coupled with data on work and safety practices to investigate workplace safety programs and improvement strategies. The thesis investigated the potential impact of different safety intervention programs prior to their implementation within the workplace. As there was a lack of mathematical modelling of the interactions between workers and workplace safety intervention programs and how these interactions and programs impacted the safety of the worker while at work, this research presents mathematical models that may be used as a basis for further investigation regarding Occupational Health and Safety.

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Chan, Hing-kai, and 陳慶佳. "Impacts of flexibility in delivery quantity and due date on supply chain dynamics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B3857651X.

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McTaggart, Kevin Andrew. "Hydrodynamics and risk analysis of iceberg impacts with offshore structures." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30733.

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The evaluation of design iceberg impact loads for offshore structures and the influence of hydrodynamic effects on impact loads are examined. Important hydrodynamic effects include iceberg added mass, wave-induced oscillatory iceberg motions, and the influence of a large structure on the surrounding flow field and subsequent velocities of approaching icebergs. The significance of these phenomena has been investigated using a two-body numerical diffraction model and through a series of experiments modelling the drift of various sized icebergs driven by waves and currents approaching a large offshore structure. Relevant findings from the hydrodynamic studies have been incorporated into two probabilistic models which can be used to determine design iceberg collision events with a structure based on either iceberg kinetic energy upon impact or global sliding force acting on the structure. Load exceedence probabilities from the kinetic energy and sliding force models are evaluated using the second-order reliability method. Output from the probabilistic models can be used to determine design collision parameters and to assess whether more sophisticated modelling of various impact processes is required. The influence of the structure on velocities of approaching icebergs is shown to be significant when the structure horizontal dimension is greater than twice the iceberg dimension. As expected, wave-induced oscillatory motions dominate the collision velocity for smaller icebergs but have a negligible effect on velocity for larger icebergs. Applied Science, Faculty of Civil Engineering, Department of Graduate

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