Dissertations / Theses on the topic 'Melodic analysis Mathematical models'
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Roschat, Christina [Verfasser]. "Mathematical Analysis of Marine Ecosystem Models / Christina Roschat." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1111558604/34.
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Keita, Sana. "Eulerian Droplet Models: Mathematical Analysis, Improvement and Applications." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37907.
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The Eulerian description of dispersed two-phase flows results in a system of
partial differential equations describing characteristics of the flow, namely volume
fraction, density and velocity of the two phases, around any point in space over
time. When pressure forces are neglected or a same pressure is considered for both
phases, the resulting system is weakly hyperbolic and solutions may exhibit vacuum
states (regions void of the dispersed phase) or localized unbounded singularities (delta shocks) that are not physically desirable. Therefore, it is crucial to find a physical way for preventing the formation of such undesirable solutions in weakly hyperbolic Eulerian two-phase flow models.
This thesis focuses on the mathematical analysis of an Eulerian model for air-
droplet flows, here called the Eulerian droplet model. This model can be seen as the
sticky particle system with a source term and is successfully used for the prediction
of droplet impingement and more recently for the prediction of particle flows in air-
ways. However, this model includes only one-way momentum exchange coupling, and develops delta shocks and vacuum states. The main goal of this thesis is to improve this model, especially for the prevention of delta shocks and vacuum states, and the adjunction of two-way momentum exchange coupling. Using a characteristic analysis, the condition for loss of regularity of smooth solutions of the inviscid Burgers
equation with a source term is established. The same condition applies to the droplet
model. The Riemann problems associated, respectively, to the Burgers equation with
a source term and the droplet model are solved. The characteristics are curves that
tend asymptotically to straight lines. The existence of an entropic solution to the
generalized Rankine-Hugoniot conditions is proven. Next, a way for preventing the
formation of delta shocks and vacuum states in the model is identified and a new
Eulerian droplet model is proposed. A new hierarchy of two-way coupling Eulerian
models is derived. Each model is analyzed and numerical comparisons of the models
are carried out. Finally, 2D computations of air-particle flows comparing the new
Eulerian droplet model with the standard Eulerian droplet model are presented.
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Racheal, Cooper. "Analysis of Mathematical Models of the Human Lung." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3289.
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The processes of lung ventilation and perfusion, diffusion, and gas transport make up the system of breathing and tissue oxygenation. Here, we present several mathematical formulations of the essential processes that contribute to breathing. These models aid in our understanding and analysis of this complex system and can be used to form treatments for patients on ventilators. With the right analysis and treatment options, patients can be helped and money can be saved. We conclude with the formulation of a mathematical model for the exchange of gasses in the body based on basic reaction kinetics.
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Wu, Guangxi. "Sensitivity and uncertainty analysis of subsurface drainage design." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28529.
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Literature on subsurface drainage theories, determination of drainage parameters, and analysis approaches of uncertainty was reviewed. Sensitivity analysis was carried out on drain spacing equations for steady state and nonsteady state, in homogeneous soils and in layered soils. It was found that drain spacing is very sensitive to the hydraulic conductivity,
the drainage coefficient, and the design midspan water table height. Spacing is not sensitive to the depth of the impermeable layer and the drain radius. In transient state, spacing is extremely sensitive to the midspan water table heights if the water table fall is relatively small. In that case steady state theory will yield more reliable results and its use is recommended. Drain spacing is usually more sensitive to the hydraulic conductivity
of the soil below the drains than to that of the soil above the drains. Therefore, it is desirable to take samples from deeper soil when measuring hydraulic conductivity. A new spacing formula was developed for two-layered soils and a special case of three-layered soils with drains at the interface of the top two layers. This equation was compared with the Kirkham equation. The new formula yields spacings close to the Kirkham equation if the hydraulic conductivity of the soil above the drains is relatively small; otherwise, it tends to give more accurate results. First and second order analysis methods were employed to analyze parameter uncertainty in subsurface drainage design. It was found that conventional design methods based on a deterministic framework may result in inadequate
spacing due to the uncertainty involved. Uncertainty may be incorporated into practical design by using the simple equations and graphs presented in this research; the procedure was illustrated through an example. Conclusions were drawn from the present study and recommendations were made for future research.Applied Science, Faculty of
Graduate
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El-Hachem, Maud. "Mathematical models of biological invasion." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232864/1/Maud_El-Hachem_Thesis.pdf.
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This thesis studies mathematical models of a population of cells invading the surrounding environment or another living population. A classical single-species model is reformulated using a moving boundary to track the position of the moving front of the invading population. The moving boundary is also used to separate two populations. Other models studied are coupled partial differential equations to describe the interaction of a population with another one. Different types of interaction are represented: the degradation of healthy skin by cancer and the growth of bone tissue on substrate.
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Harris, David Wayne. "A degradation analysis methodology for maintenance tasks." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/24867.
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Mercurio, Matthew Forrest. "Divider analysis of drainage divides delineated at the field scale." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1306855.
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Previous works have applied the Divider Method to the shapes of drainage divides as measured from maps. This study focuses on the shapes of several drainage divides measured in the field at very fine scale. These divides, chosen for their sharp crests, include portions of the Continental Divide in Colorado and badlands-type divides in Arizona, Wyoming, South Dakota, and Texas. The badlands type divides were delineated using a laser theodolite to collect data at decimeter point spacing, and the Continental Divide segments were delineated using pace and bearing at a constant point spacing of 30 meters. A GIS was used to store and visualize the divide data, and an automated divider analysis was performed for each of the 16 drainage divides.The Richardson plots produced for each of the drainage divide datasets were visually inspected for portions of linearity. Fractal dimensions (D) were calculated using linear regression techniques for each of the linear segments identified in the Richardson plots. Six of the plots exhibited two distinct segments of linearity, nine plots exhibited one segment, and one plot exhibited no segments of linearity. Residual analyses of the trend lines show that about half of the Richardson plot segments used to calculate D exhibit slight curvature. While these segments are not strictly linear, linear models and associated D values may still serve well as approximations to describe degree of divide wandering.Most (20 out of 21) of the dimensions derived from the Richardson plots for the drainage divides fall within the range from 1.01-1.07. The D values calculated for the Continental Divide range from 1.02-1.07. The dimensions calculated for the badlandtype divides were distributed evenly across the range of 1.01-1.06, with a single exceptional D value at 1.12. Only four of the divide D values fall within a range of 1.06–1.12, the range for D established for drainage divides in published map-based studies, despite the apparent dominance of erosion processes on the measured divides.Department of Geology
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Beckham, Jon Regan. "Analysis of mathematical models of electrostatically deformed elastic bodies." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 169 p, 2008. http://proquest.umi.com/pqdweb?did=1475178561&sid=27&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Tumanova, Natalija. "The Numerical Analysis of Nonlinear Mathematical Models on Graphs." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120720_121648-24321.
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The numerical algorithms for non-stationary mathematical models in non-standard domains are investigated in the dissertation. The problem definition domain is represented by branching structures with conjugation equations considered at the branching points. The numerical analysis of the conjugation equations and non-classical boundary conditions distinguish considered problems among the classical problems of mathematical physics presented in the literature. The scope of the dissertation covers the investigation of stability and convergence of the numerical algorithms on branching structures with different conjugation equations, the construction and implementation of parallel algorithms, the investigation of the numerical schemes for the problems with nonlocal integral conditions. The modeling of the excitation of neuron and photoexcited carrier decay in a semiconductor, also the problem of the identification of nonlinear model are considered in the dissertation.Disertacijoje nagrinėjami nestacionarių matematinių modelių nestandartinėse srityse skaitiniai sprendimo algoritmai. Uždavinio formulavimo sritis yra šakotosios strukturos (ang. branching structures), kurių išsišakojimo taškuose apibrežiami tvermės dėsniai. Tvermės dėsnių skaitinė analizė ir nestandartinių kraštinių sąlygų analizė skiria nagrinėjamus uždavinius nuo klasikinių aprašytų literatūroje matematinės fizikos uždaviniu. Disertacijoje suformuluoti uždaviniai apima skaitinių algoritmų šakotose struktūrose su skirtingais srautų tvermės dėsniais stabilumo ir konvergavimo tyrimą, lygiagrečiųjų algoritmų sudarymą ir taikymą, skaitinių schemų uždaviniams su nelokaliomis integralinėmis sąlygomis tyrimą. Disertacijoje sprendžiami taikomieji neurono sužadinimo ir impulso relaksacijos lazerio apšviestame puslaidininkyje uždaviniai, netiesinio modelio identifikavimo uždavinys.
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Chiang, T. "Mathematical and statistical models for the analysis of protein." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597600.
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Protein interactions, both amongst themselves and with other molecules, are responsible for much of the work within the cellular machine. As the number of protein interaction data sets grow in number and in size, from experiments such as Yeast 2-Hybrid or Affinity Purification followed by Mass Spectrometry, there is a need to analyse the data both quantitatively and qualitatively. One area of research is determining how reliable a report of a protein interaction is – whether it could be reproduced if the experiment were repeated, or if it were tested using an independent assay. One might aim to score each reported interaction using a quantitative measure of reliability. Ultimately, protein interactions need to be addressed at the systems level where both the dynamic and functional nature of protein complexes and other types of interactions is ascertained. In this dissertation, I present two methodological developments that are useful towards elucidating the nature of protein interaction graphs in the model organism Saccharomyces cerevisiae. The first one aims to estimate the sensitivity and specificity of a protein interaction data set, and does that, as much as possible, by looking at the data set’s internal consistency and reproducibility. The second method aims to estimate the node degree distribution, using a multinomial model which is fit by maximum likelihood. In the development of the methods for the analysis of the protein interactions, computational tools were built in the statistical environment R. Such tools are necessary for the implementation of each analytic step, for rendering visualisations of intermediate and conclusive results, and for the construction of optimal work-flows so as to make our research reproducible and extensible. We have also included such a work-flow in this dissertation as well as the software engineering component of the research.
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De, la Harpe Alana. "A comparative analysis of mathematical models for HIV epidemiology." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96983.
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Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: HIV infection is one of the world’s biggest health problems, with millions of people infected worldwide. HIV infects cells in the immune system, where it primarily targets CD4+ T helper cells and without treatment, the disease leads to the collapse of the host immune system and ultimately death. Mathematical models have been used extensively to study the epidemiology of HIV/AIDS. They have proven to be effective tools in studying the transmission dynamics of HIV. These models provide predictions that can help better our understanding of the epidemiological patterns of HIV, especially the mechanism associated with the spread of the disease. In this thesis we made a functional comparison between existing epidemiological models for HIV, with the focus of the comparison on the force of infection (FOI). The spread of infection is a crucial part of any infectious disease, as the dynamics of the disease depends greatly on the rate of transmission from an infectious individual to a susceptible individual. First, a review was done to see what deterministic epidemiological models exist. We found that many manuscripts do not provide the necessary information to recreate the authors’ results and only a small amount of the models could be simulated. The reason for this is mainly due to a lack of information or due to mistakes in the article. The models were divided into four categories for the analysis. On the basis of the FOI, we distinguished between frequency- or density-dependent transmission, and as a second criterion we distinguished models on the sexual activity of the AIDS group. Subsequently, the models were compared in terms of their FOI, within and between these classes. We showed that for larger populations, frequency-dependent transmission should be used. This is the case for HIV, where the disease is mainly spread through sexual contact. Inclusion of AIDS patients in the group of infectious individuals is important for the accuracy of transmission dynamics. More than half of the studies that were selected in the review assumed that AIDS patients are too sick to engage in risky sexual behaviour. We see that including AIDS patients in the infectious individuals class has a significant effect on the FOI when the value for the probability of transmission for an individual with AIDS is bigger than that of the other classes. The analysis shows that the FOI can vary depending on the parameter values and the assumptions made. Many models compress various parameter values into one, most often the transmission probability. Not showing the parameter values separately makes it difficult to understand how the FOI works, since there are unknown factors that have an influence. Improving the accuracy of the FOI can help us to better understand what factors influence it, and also produce more realistic results. Writing the probability of transmission as a function of the viral load can help to make the FOI more accurate and also help in the understanding of the effects that viral dynamics have on the population transmission dynamics.
AFRIKAANSE OPSOMMING: MIV-infeksie is een van die wêreld se grootste gesondheidsprobleme, met miljoene mense wat wêreldwyd geïnfekteer is. MIV infekteer selle in die immuunstelsel, waar dit hoofsaaklik CD4+ T-helperselle teiken. Sonder behandeling lei die siekte tot die ineenstorting van die gasheer se immuunstelsel en uiteindelik sy dood. Wiskundige modelle word breedvoerig gebruik om die epidemiologie van MIV/vigs te bestudeer. Die modelle is doeltreffende instrumente in die studie van die oordrag-dinamika van MIV. Hulle lewer voorspellings wat kan help om ons begrip van epidemiologiese patrone van MIV, veral die meganisme wat verband hou met die verspreiding van die siekte, te verbeter. In hierdie tesis het ons ‘n funksionele vergelyking tussen bestaande epidemiologiese modelle vir MIV gedoen, met die fokus van die vergelyking op die tempo van infeksie (TVI). Die verspreiding van infeksie is ‘n belangrike deel van enige aansteeklike siekte, aangesien die dinamika van die siekte grootliks afhang van die tempo van oordrag van ‘n aansteeklike persoon na ‘n vatbare persoon. ‘n Oorsig is gedoen om te sien watter kompartementele epidemiologiese modelle alreeds bestaan. Ons het gevind dat baie van die manuskripte nie die nodige inligting voorsien wat nodig is om die resultate van die skrywers te repliseer nie, en slegs ‘n klein hoeveelheid van die modelle kon gesimuleer word. Die rede hiervoor is hoofsaaklik as gevolg van ‘n gebrek aan inligting of van foute in die artikel. Die modelle is in vier kategorieë vir die analise verdeel. Op grond van die TVI het ons tussen frekwensie- of digtheidsafhanklike oordrag onderskei, en as ‘n tweede kriterium het ons die modelle op die seksuele aktiwiteit van die vigs-groep onderskei. Daarna is die modelle binne en tussen die klasse vergelyk in terme van hul TVIs. Daar is gewys dat frekwensie-afhanklike oordrag gebruik moet word vir groter bevolkings. Dit is die geval van MIV, waar die siekte hoofsaaklik versprei word deur seksuele kontak. Die insluiting van die vigs-pasiënte in die groep van aansteeklike individue is belangrik vir die akkuraatheid van die oordrag-dinamika van MIV. Meer as helfte van die uitgesoekte studies aanvaar dat vigs-pasiënte te siek is om betrokke te raak by riskante seksuele gedrag. Ons sien dat die insluiting van vigs-pasiënte in die groep van aansteeklike individue ‘n beduidende uitwerking op die TVI het wanneer die waarde van die waarskynlikheid van oordrag van ‘n individu met vigs groter is as dié van die ander klasse. Die analise toon dat die TVI kan wissel afhangende van die parameter waardes en die aannames wat gemaak is. Baie modelle voeg verskeie parameter waardes bymekaar vir die waarskynlikheid van oordrag. Wanneer die parameter waardes nie apart gewys word nie, is dit moeilik om die werking van die TVI te verstaan, want daar is onbekende faktore wat ‘n invloed op die TVI het. Die verbetering van die akkuraatheid van die TVI kan ons help om die faktore wat dit beïnvloed beter te verstaan, en dit kan ook help om meer realistiese resultate te produseer. Om die waarskynlikheid van oordrag as ‘n funksie van die viruslading te skryf kan help om die TVI meer akkuraat te maak en dit kan ook help om die effek wat virale dinamika op die bevolkingsoordrag-dinamika het, beter te verstaan.
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Serkov, S. K. "Asymptotic analysis of mathematical models for elastic composite media." Thesis, University of Bath, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390311.
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Lee, M. E. M. "Mathematical models of the carding process." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249543.
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Carding is an essential pre-spinning process whereby masses of dirty tufted fibres are cleaned, disentangled and refined into a smooth coherent web. Research and development in this `low-technology' industry have hitherto depended on empirical evidence. In collaboration with the School of Textile Industries at the University of Leeds, a mathematical theory has been developed that describes the passage of fibres through the carding machine. The fibre dynamics in the carding machine are posed, modelled and simulated by three distinct physical problems: the journey of a single fibre, the extraction of fibres from a tuft or tufts and many interconnecting, entangled fibres. A description of the life of a single fibre is given as it is transported through the carding machine. Many fibres are sparsely distributed across machine surfaces, therefore interactions with other neighbouring fibres, either hydrodynamically or by frictional contact points, can be neglected. The aerodynamic forces overwhelm the fibre's ability to retain its crimp or natural curvature, and so the fibre is treated as an inextensible string. Two machine topologies are studied in detail, thin annular regions with hooked surfaces and the nip region between two rotating drums. The theoretical simulations suggest that fibres do not transfer between carding surfaces in annular machine geometries. In contrast to current carding theories, which are speculative, a novel explanation is developed for fibre transfer between the rotating drums. The mathematical simulations describe two distinct mechanisms: strong transferral forces between the taker-in and cylinder and a weaker mechanism between cylinder and doffer. Most fibres enter the carding machine connected to and entangled with other fibres. Fibres are teased from their neighbours and in the case where their neighbours form a tuft, which is a cohesive and resistive fibre structure, a model has been developed to understand how a tuft is opened and broken down during the carding process. Hook-fibre-tuft competitions are modelled in detail: a single fibre extracted from a tuft by a hook and diverging hook-entrained tufts with many interconnecting fibres. Consequently, for each scenario once fibres have been completely or partially extracted, estimates can be made as to the degree to which a tuft has been opened-up. Finally, a continuum approach is used to simulate many interconnected, entangled fibre-tuft populations, focusing in particular on their deformations. A novel approach describes this medium by density, velocity, directionality, alignment and entanglement. The materials responds to stress as an isotropic or transversely isotropic medium dependent on the degree of alignment. Additionally, the material's response to stress is a function of the degree of entanglement which we describe by using braid theory. Analytical solutions are found for elongational and shearing flows, and these compare very well with experiments for certain parameter regimes.
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Crawford, David Michael. "Analysis of biological pattern formation models." Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:aaa19d3b-c930-4cfa-adc6-8ea498fa5695.
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In this thesis we examine mathematical models which have been suggested as possibile mechanisms for forming certain biological patterns. We analyse them in detail attempting to produce the requisite patterns both analytically and numerically. A reaction diffusion system in two spatial dimensions with anisotropic diffusion is examined in detail and the results compared with certain snakeskin patterns. We examine two other variants to the standard reaction diffusion system: a system where the reaction kinetics and the diffusion coefficients depend upon the cell density suggested as a possible model for the segmentation sequence in Drosophila and a system where the model parameters have one dimensional spatial gradients. We also analyse a model derived from known cellular processes used to model the branching behaviour in bryozoans and show that, in one dimension, such a model can, in theory, give all the required solution behaviour. A genetic switch model for pattern elements on butterfly wings is also briefly examined to obtain expressions for the solution behaviour under coldshock.
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Hakami, Amir. "Direct sensitivity analysis in air quality models." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180202/unrestricted/hakami%5Famir%5F200312%5Fphd.pdf.
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Akileh, Aiman R. "Elastic-plastic analysis of axisymmetrically loaded isotropic circular and annular plates undergoing large deflections." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3559.
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The concept of load analogy is used in the elastic and elastic-plastic analysis of isotropic circular and annular plates undergoing moderately large deflection. The effects of the nonlinear terms of lateral displacement and the plastic strains are considered as additional fictitious lateral loads, edge moments, and in-plane forces acting on the plate. The solution of an elastic or elastic-plastic Von Karman type plate is hence reduced to a set of two equivalent elastic plate problems with small displacements, namely, a plane problem in elasticity and a linear elastic plate bending problem. The method of finite element is employed to solve the plane stress problem. The large deflection solutions are then obtained by utilizing the solutions of the linear bending problems through an iterative numerical scheme. The flow theory of plasticity incorporating a Von Mises layer yield criterion and the Prandtl-Reuss associated flow rule for strain hardening materials is employed in this approach.
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Sood, Premlata Khetan. "Profit sharing, unemployment, and inflation in Canada : a simulation analysis." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34459.
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The thesis examines the impact of a partial switch to a share system in Canada on unemployment and inflation. Simulations with an independent Canadian macro model and Canadian data for the period 1973-1983 show that profit sharing will not always resolve unemployment and inflation, as claimed by Martin Weitzman. Some combinations of the share parameters resolve them, while others aggravate them. Thus, the combinations of the share parameters play a key role in terms of impact of the profit sharing on unemployment and inflation.
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Khalilzadeh, Amir Hossein. "Variance Dependent Pricing Kernels in GARCH Models." Thesis, Uppsala universitet, Analys och tillämpad matematik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-180373.
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Haseeb, Hayat. "A Comparison of Models for Oil Futures." Thesis, Uppsala universitet, Analys och tillämpad matematik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-202847.
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YU, CHUNG-CHYI. "FINITE-ELEMENT ANALYSIS OF TIME-DEPENDENT CONVECTION DIFFUSION EQUATIONS (PETROV-GALERKIN)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183930.
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Petrov-Galerkin finite element methods based on time-space elements are developed for the time-dependent multi-dimensional linear convection-diffusion equation. The methods introduce two parameters in conjunction with perturbed weighting functions. These parameters are determined locally using truncation error analysis techniques. In the one-dimensional case, the new algorithms are thoroughly analyzed for convergence and stability properties. Numerical schemes that are second order in time, third order in space and stable when the Courant number is less than or equal to one are produced. Extensions of the algorithm to nonlinear Navier-Stokes equations are investigated. In this case, it is found more efficient to use a Petrov-Galerkin method based on a one parameter perturbation and a semi-discrete Petrov-Galerkin formulation with a generalized Newmark algorithm in time. The algorithm is applied to the two-dimensional simulation of natural convection in a horizontal circular cylinder when the Boussinesq approximation is valid. New results are obtained for this problem which show the development of three flow regimes as the Rayleigh number increases. Detailed calculations for the fluid flow and heat transfer in the cylinder for the different regimes as the Rayleigh number increases are presented.
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Venter, Daniel Jacobus Lodewyk. "The consolidation of forecests with regression models." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1020964.
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The primary objective of this study was to develop a dashboard for the consolidation of multiple forecasts utilising a range of multiple linear regression models. The term dashboard is used to describe with a single word the characteristics of the forecasts consolidation application that was developed to provide the required functionalities via a graphical user interface structured as a series of interlinked screens. Microsoft Excel© was used as the platform to develop the dashboard named ConFoRM (acronym for Consolidate Forecasts with Regression Models). The major steps of the consolidation process incorporated in ConFoRM are: 1. Input historical data. Select appropriate analysis and holdout samples. 3. Specify regression models to be considered as candidates for the final model to be used for the consolidation of forecasts. 4. Perform regression analysis and holdout analysis for each of the models specified in step 3. 5. Perform post-holdout testing to assess the performance of the model with best holdout validation results on out-of-sample data. 6. Consolidate forecasts. Two data transformations are available: the removal of growth and time-periods effect from the time series; a translation of the time series by subtracting ̅i, the mean of all the forecasts for data record i, from the variable being predicted and its related forecasts for each data record I. The pre-defined regression models available for ordinary least square linear regression models (LRM) are: a. A set of k simple LRM’s, one for each of the k forecasts; b. A multiple LRM that includes all the forecasts: c. A multiple LRM that includes all the forecasts and as many of the first-order interactions between the input forecasts as allowed by the sample size and the maximum number of predictors provided by the dashboard with the interactions included in the model to be those with the highest individual correlation with the variable being predicted; d. A multiple LRM that includes as many of the forecasts and first-order interactions between the input forecasts as allowed by the sample size and the maximum number of predictors provided by the dashboard: with the forecasts and interactions included in the model to be those with the highest individual correlation with the variable being predicted; e. A simple LRM with the predictor variable being the mean of the forecasts: f. A set of simple LRM’s with the predictor variable in each case being the weighted mean of the forecasts with different formulas for the weights Also available is an ad hoc user specified model in terms of the forecasts and the predictor variables generated by the dashboard for the pre-defined models. Provision is made in the regression analysis for both of forward entry and backward removal regression. Weighted least squares (WLS) regression can be performed optionally based on the age of forecasts with smaller weight for older forecasts.
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Musa, Zulkarnain 1964. "An accelerated conjugate direction procedure for slope stability analysis." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276912.
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CSLIP2 (De Natale, 1987) is the only slope stability program that utilizes a "direction set" optimization routine in its search for the minimum safety factor. However, CSLIP2 which employs Powell's Conjugate Direction Method permits only the horizontal and vertical directions (x and y) to be used as the initial direction set. The efficiency of the existing search routine is improved by replacing the x-y coordinate directions with initial directions that are parallel to and perpendicular to the principal axis of the safety factor contours.
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鄭定陽 and Dingyang Zheng. "Vibration and stability analysis of plate-type structures under movingloads by analytical and numercial methods." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31239791.
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Hildebrand, Paul. "The use of absorbing boundaries in the analysis of bankruptcy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34550.pdf.
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Grm, Aleksander. "Mathematical analysis of macroscopic models for slow dense granular flow." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=98408214X.
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Font, Moragón Carme. "Mathematical models for energy and landscape integrated analysis in agroecosystems." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/399906.
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Els models matemàtics s'utilitzen per explicar fenòmens naturals. Com que els fenòmens naturals són molt complexes, per tal d'aprofundir en el seu comportament i ser capaç de fer prediccions sobre ells, es necessita passar per un procés de simplificació. En el procés de creació del model, el sistema es tradueix a llenguatge matemàtic que permet l'estudi del sistema des d'un nou punt de vista. En aquesta tesi, es consideren models estadístics per estudiar el comportament dels agroecosistemes a diferents escales espacials.
L'objectiu d'aquest treball és estudiar la relació entre fluxos d'energia, canvis de cobertes del sòl, la funcionalitat del paisatge i la biodiversitat que subjau en els agroecosistemes. Per a això, es proposen models basats en tals matèries. Les principals unitats d'anàlisi seran les cobertes del sòl, quan treballem a escala regional, i els usos del sòl, a escala local.
En el segon capítol, es presenta un model de pertorbació-complexitat intermèdia (IDC) dels paisatges culturals. Aquest enfocament té com a objectiu avaluar com els diferents nivells de pertorbacions antropogèniques sobre els ecosistemes afecten la capacitat d'acollir la biodiversitat en funció de l'heterogeneïtat d'usos sòl. S'aplica a l'illa de Mallorca, enmig de la zona activa de la biodiversitat mediterrània, a escala regional i de paisatge.
El model utilitza la pertorbació exercida pels agricultors que alteren la producció primària neta a través del canvi d'usos del sòl, així com l'eliminació d'una part d'ella, juntament amb l'índex de Shannon-Wiener de la diversitat d'usos del sòl. El model es prova en un disseny experimental a dues escales al llarg de tres punts de temps. La riquesa d'espècies d'aus nidificants i hivernants, preses com a indicador de la biodiversitat, s'utilitza en una anàlisi factorial exploratori.
Seguint la idea presentada en el segon capítol, en el tercer capítol es presenta un mètode per descriure la relació entre els indicadors d'heterogeneïtat d'usos del sòl, i l'apropiació humana de la producció primària neta en una regió determinada. Aquestes quantitats són vistes com a funcions del vector de proporcions de les cobertes de sòl, que al seu torn es tracta com un vector aleatori els valors del qual depenen de la unitat de terreny que s'observa.
Presentem el mètode suposant, en primer lloc, que el vector de proporcions segueix una distribució uniforme en el símplex. Després, considerem com a punt de partida un conjunt de dades mostals, de manera que primer hem d'obtenir una estimació de la seva distribució de probabilitat teòrica, i en segon lloc, generem una mostra de grans dimensions seguint la distribució estimada. Apliquem aquest procediment a dades de l'illa de Mallorca en tres moments de temps diferents.
L'objectiu principal aquí és calcular el valor esperat de la diversitat del paisatge com a funció del nivell d'apropiació humana. Aquesta funció està relacionada amb l'anomenada hipòtesi d'energia i espècies, i amb l'hipòtesi de la Pertorbació Intermèdia.
Finalment, el quart capítol està dedicat a tractar els processos interns dels agroecosistemes. Per a aquest propòsit, es proposa un graf que representa el patró de fluxos d'energia en un agroecosistema. Utilitzem aquest graf per calcular el nivell d'emmagatzematge d'energia dins de l'agroecosistema, així com la informació inclosa en aquesta xarxa de fluxos, a escales tant local com de paisatge.
Per tant, es proposa un model d'anàlisi integrat d'energia i paisatge (ELIA) que avalua tant la complexitat dels bucles d'energia interna, com la informació continguda en tota la xarxa de fluxos d'energia soci-metabòliques, per tal de correlacionar aquesta interacció d'informació energètica amb l'estructura funcional del paisatge. A l'annex, es suggereix una millora de l'indicador d'informació. ELIA es prova en el Vallès, a la Regió Metropolitana de Barcelona.Mathematical models are used to better explain natural phenomena. Since natural phenomena are very complex, in order to delve into their behaviour and be able to do predictions over them, a simplification process of such systems is needed. In the process of creating the model, the system is translated into mathematical language that allows the study of the system from a new point of view. In this thesis, statistical models are considered to study the behaviour of agroecosystems at different spatial scales. The aim of this work is to study the relation between energy flows, land cover changes, landscape functionality and the biodiversity that underlies in agroecosystems. For this, models based on such matters are proposed. The main units of analysis will be the land covers, when we work at regional scale, and the land uses, at local scale. In the second chapter, an intermediate disturbance-complexity model (IDC) of cultural landscapes is presented. This approach is aimed at assessing how different levels of anthropogenic disturbance on ecosystems affect the capacity to host biodiversity depending on the land matrix heterogeneity. It is applied to the Mallorca Island, amidst the Mediterranean biodiversity hotspot, at regional and landscape scales. The model uses the disturbance exerted by farmers altering the Net Primary Production (NPP) through land use change, as well as removing a share of it, together with Shannon-Wiener index of land use diversity. The model is tested with a twofold-scalar experimental design of a set of landscape units along three time points. Species richness of breeding and wintering birds, taken as a biodiversity proxy, is used in an exploratory factor analysis. Following the idea presented in the second chapter, in the third chapter we present a method to describe the relation between indicators of the land matrix heterogeneity, and the human appropriation of the net primary production in a given region. These quantities are viewed as functions of the vector of proportions of the different land covers, which is in turn treated as a random vector whose values depend on the particular small terrain cell that is observed. We illustrate the method assuming first that the vector of proportions follows a uniform distribution on the simplex. We then consider as starting point a raw dataset of proportions for each cell, for which we must first obtain an estimate of its theoretical probability distribution, and secondly generate a sample of large size from it. We apply this procedure to real historical data of the Mallorca Island in three different time points. The main goal here is to compute the mean value of the land covers diversity as a function of the level of human appropriation of net primary production. This function is related to the so-called Energy-Species hypothesis and to the Intermediate Disturbance Hypothesis. Finally, fourth chapter is devoted to deal with agroecosystems internal processes. For this purpose, a graph to represent the pattern of energy flows in an agroecosystem is presented. We use this graph model to calculate the level of energy storage within the agroecosystem provided by its ‘internal feedback’, as well as the information embedded in this network of flows, at local and landscape scales. Thus, we propose an Energy-Landscape Integrated Analysis (ELIA) model that assesses both the complexity of internal energy loops, and the information held in the whole network of socio-metabolic energy fluxes, so as to correlate this energy-information interplay with the functional landscape structure. In the annex, an improvement of the information indicator is suggested. ELIA is tested in the Vallès County of the Barcelona Metropolitan Region.
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Otieno, Andrew Alex Omondi. "Application of lie group analysis to mathematical models in epidemiology." Thesis, Walter Sisulu University, 2013. http://hdl.handle.net/11260/100.
Full textAbstract:
Lie group analysis is arguably the most systematic vehicle for finding exact solutions of differential equations. Using this approach one has at one's disposal a variety of algorithms that make the solution process of many differential equations algorithmic. Vital properties of a given differential equation can often be inferred from the symmetries admitted by the equation. However, Lie group analysis has not enjoyed wide-spread application to systems of first-order ordinary differential equations. This is because such systems typically admit an infinite number of Lie point symmetries, and there is no systematic way to find even a single nontrivial one-dimensional Lie symmetry algebra. In the few applications available, the approach has been to circumvent the problem by transforming a given system of first-order ordinary differential equations into one in which at least one of the equations is of order two or greater. It is therefore fair to say that the full power of Lie group analysis has not been sufficiently harnessed in the solution of systems of first-order ordinary differential equations. In this dissertation we review some applications of Lie group analysis to systems of first order ordinary differential equations. We shed light on the integration procedure for first-order systems of ordinary differential equations admitting a solvable Lie algebra. We do this via instructive examples drawn from mathematical epidemiology models. In particular we revisit the work of Nucci and Torrisi [54] and improve the exposition of the Lie-symmetry-inspired solution of a mathematical model which describes a HIV transmission. To aid implementation of the integration strategy for systems of ordinary differential equations, we have developed ad-hoc routines for finding particular types of admitted symmetries and checking if a given symmetry is indeed admitted by a system of ordinary differential equations.
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Danbaba, Usman Ahmed. "Mathematical models and analysis for the transmission dynamics of malaria." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/53483.
Full textAbstract:
Malaria is one of the most widespread and complex parasitic diseases in the world.
According to the World Health Organization's records for the year 2013, there
were 207 million malaria cases with 627,000 deaths in 2012 globally. Although its
control and prevention has been pursued for a long time, however, because the
parasite developed resistance to many of the standard treatments, it is becoming
more di cult for researchers to stay ahead of the disease. In this dissertation, two
deterministic models for the transmission dynamics of malaria are presented. First
we comprehensively studied the dynamical interaction of sporozoites with humans,
production of merozoites, and the invasion of red blood cells during erythrocytic
stage of malaria infection. Then we construct a model, which takes the form of
an autonomous deterministic system of non-linear di erential equations with standard
incidence, consisting of seven mutually-exclusive compartments representing
the human and vector dynamics. The model is then extended to incorporate additional
compartment of vaccinated individuals. Rigorous analysis of the two models (with and without vaccine) shows that, both the non-vaccinated and vaccinated
models have a locally asymptotically stable disease-free equilibrium (DFE) whenever
their respective threshold parameters, known as the basic reproduction number
and the vaccinated reproduction number are respectively less than unity, and the
DFE is unstable when they are greater than unity. In addition, the models exhibit
the phenomenon of backward bifurcation, where the stable disease-free equilibrium
coexists with a stable endemic equilibrium when the associated reproduction numbers
are less than unity. Furthermore, it was shown that, the backward bifurcation
phenomenon can be removed by substituting the associated standard incidence
function with the mass action incidence, this is achieved using Lyapunov functions
in conjunction with LaSalle invariance principle. We further presented numerical
simulations using parameter values for both low and high malaria incidence regions.Dissertation (MSc)--University of Pretoria, 2015.
Mathematics and Applied Mathematics
MSc
Unrestricted
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Oremland, Matthew Scott. "Techniques for mathematical analysis and optimization of agent-based models." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25138.
Full textAbstract:
Agent-based models are computer simulations in which entities (agents) interact with each other and their environment according to local update rules. Local interactions give rise to global dynamics. These models can be thought of as in silico laboratories that can be used to investigate the system being modeled. Optimization problems for agent-based models are problems concerning the optimal way of steering a particular model to a desired state. Given that agent-based models have no rigorous mathematical formulation, standard analysis is difficult, and traditional mathematical approaches are often intractable.
This work presents techniques for the analysis of agent-based models and for solving optimization problems with such models. Techniques include model reduction, simulation optimization, conversion to systems of discrete difference equations, and a variety of heuristic methods. The proposed strategies are novel in their application; results show that for a large class of models, these strategies are more effective than existing methods.Ph. D.
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Tosun, Kursad. "QUALITATIVE AND QUANTITATIVE ANALYSIS OF STOCHASTIC MODELS IN MATHEMATICAL EPIDEMIOLOGY." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/dissertations/732.
Full textAbstract:
We introduce random fluctuations on contact and recovery rates in three basic deterministic models in mathematical epidemiology and obtain stochastic counterparts. This paper addresses qualitative and quantitative analysis of stochastic SIS model with disease deaths and demographic effects, and stochastic SIR models with/without disease deaths and demographic effects. We prove the global existence of a unique strong solution and discuss stochastic asymptotic stability of disease free and endemic equilibria. We also investigate numerical properties of these models and prove the convergence of the Balanced Implicit Method approximation to the analytic solution. We simulate the models with fairly realistic parameters to visualize our conclusions.
31
Danbaba, Ahmed. "Mathematical models and analysis for the transmission dynamics of malaria." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/53483.
Full textAbstract:
Malaria is one of the most widespread and complex parasitic diseases in the world.
According to the World Health Organization's records for the year 2013, there
were 207 million malaria cases with 627,000 deaths in 2012 globally. Although its
control and prevention has been pursued for a long time, however, because the
parasite developed resistance to many of the standard treatments, it is becoming
more di cult for researchers to stay ahead of the disease. In this dissertation, two
deterministic models for the transmission dynamics of malaria are presented. First
we comprehensively studied the dynamical interaction of sporozoites with humans,
production of merozoites, and the invasion of red blood cells during erythrocytic
stage of malaria infection. Then we construct a model, which takes the form of
an autonomous deterministic system of non-linear di erential equations with standard
incidence, consisting of seven mutually-exclusive compartments representing
the human and vector dynamics. The model is then extended to incorporate additional
compartment of vaccinated individuals. Rigorous analysis of the two models (with and without vaccine) shows that, both the non-vaccinated and vaccinated
models have a locally asymptotically stable disease-free equilibrium (DFE) whenever
their respective threshold parameters, known as the basic reproduction number
and the vaccinated reproduction number are respectively less than unity, and the
DFE is unstable when they are greater than unity. In addition, the models exhibit
the phenomenon of backward bifurcation, where the stable disease-free equilibrium
coexists with a stable endemic equilibrium when the associated reproduction numbers
are less than unity. Furthermore, it was shown that, the backward bifurcation
phenomenon can be removed by substituting the associated standard incidence
function with the mass action incidence, this is achieved using Lyapunov functions
in conjunction with LaSalle invariance principle. We further presented numerical
simulations using parameter values for both low and high malaria incidence regions.Dissertation (MSc)--University of Pretoria, 2015.
Mathematics and Applied Mathematics
MSc
Unrestricted
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Richard, Paul François. "A computer analysis of the flow of water and nutrients in agricultural soils as affected by subsurface drainage." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29171.
Full textAbstract:
A computer model was developed in order to determine the effects of drainage practices on nutrient losses from level agricultural soils.
The model performs a daily simulation of the vertical flow of water, nitrogen, phosphorus, and heat, and of the growth of crops. A water flow submodel calculates the depth of the water table based on daily predictions of evaporation, transpiration, flow to drains and ditches, and deep percolation. An original saturated-unsaturated flow algorithm is used to determine moisture infiltration, redistribution, and upward flow in the soil matrix, as well as bypassing flow in the soil macropores and horizontal flux between the soil matrix and the macropores, and surface runoff. Nutrient movement occurs by mass flow. Heat flow, nutrient biochemical transformations, and crop growth are determined by using well established relations.
Field tests were carried out for a period of two years on an experimental site in the Lower Fraser Valley of British Columbia. The water table depth was measured on a continuous basis. Grab samples of drainwater and observation wells were obtained periodically and analyzed for nitrogen (N0₃-N, NH₄-N, and TKN) and phosphorus (P0₄-P and TP). The field results show a decrease in the concentration of all nutrients over the sampling period, and provide evidence that denitrification and bypassing flow are important mechanisms affecting the nutrient balance of this soil.
These results were used to calibrate the model. An excellent fit of the observed water table profile and an adequate fit of the observed drain concentration of nitrate were obtained. The simulation revealed that bypassing flow is a very important transfer mechanism in this soil and must be included in order to obtain a satisfactory fit of the experimental data.
A sensitivity analysis of the model showed that the patterns of moisture flow have a predominant influence on the rate of nutrient leaching. In particular, it was found that the nutrient concentration in drain water is a strong function of the hydraulic conductivity of the soil matrix and of the horizontal distance between the soil macropores, which control the ratio of moisture flow in the soil matrix to the macropore flow and the lateral diffusion of nutrients between the soil matrix and the macropores.
The effects of four different drainage designs on nutrient losses were simulated over a period of two years for three different soils and two different nutrient distributions in the soil. It was found that there is a large difference between the amount of nutrients leached from drainage systems using different drainage coefficients. There was also a large difference in the response of two drainage designs based on the same drainage coefficient but using different depth and spacing of drains. Transient effects, as determined by the initial vertical distribution of the nutrients, were seen to remain dominant over the two year duration of the simulation.
The model was found to be useful in explaining the apparent contradictions found in the literature assessing the effects of subsurface drainage on nutrient losses. The results from the model show these effects to be strongly site and condition specific. Furthermore, the model shows that soils and drainage designs that produce similar volumes of drain flow may exhibit very different leaching responses, and that drainage designs equivalent from a hydraulic standpoint can be very dissimilar in their potential for leaching nutrients. The model provides a tool which can be used to determine the appropriateness of different drainage designs in soils where minimizing nutrient losses is critical.Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate
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Blanding, James Michael. "An analytical study and computer analysis of three-dimensional, steady-state vibration of multishaft geared-rotor systems." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54198.
Full textAbstract:
A unique multifrequencied transfer matrix method performs three-dimensional harmonic, steady-state response calculations on geared-rotor systems. The full six degrees-of-freedom method includes physical branching to accommodate multiple shafting and frequency branching to simultaneously accommodate multiple frequencies and their interdependence resulting from time-varying mesh stiffness.
Areas of emphasis include development of a modified transfer matrix to handle multiple frequencies and shafting; description of the time-varying stiffness tensor representing the involute spur gear mesh based on bending, shear, compression, and local contact deformation; development of the mesh transfer matrix; development of an automatic system solver to allow the engineer to analyze systems of arbitrary construction; and the development of a matrix solver to efficiently handle large systems.
A computer analysis demonstrates the significance of terms included in the stiffness evaluation as compared with less rigorous treatment in the literature. An analytical example problem illustrates the automated model generation through complete rotor system dynamic response analysis produced by the current work with special attention to the significance of parametric excitation due to the gear mesh.Ph. D.
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Yuksel, Hasan Zafer. "Performance measures: Traditional versus new models." CSUSB ScholarWorks, 2006. https://scholarworks.lib.csusb.edu/etd-project/3086.
Full textAbstract:
The thesis analyzed the performance of 5,987 mutual funds using a database called Steele Mutual Fund Experts and compared the predicting ability of various measures of performance. The measures discussed in the thesis are Treynor Ratio, Sharpe Ratio, Jensen's Alpha, Graham-Harvey-1 (GH-1), and Graham-Harvey-2 (GH-2). The performance measures are mostly used by professional money managers and scholars for literary purposes.
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馮達淸 and Tat-ching Fung. "Steady state solutions of nonlinear dynamic systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31231809.
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Shi, Wen, and 石雯. "Dynamic simulation and quantitative analysis of urban taxi services." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45528767.
Full text
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Yeoh, Lean-Weng. "An analysis of MLAYER a multilayer tropospheric propagation program /." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA232733.
Full textAbstract:
Thesis (M.S. in Electrical Engineering and M.S. in Electrical Engineer)--Naval Postgraduate School, June 1990.Thesis Advisor(s): Lee, Hung-Mou. Second Reader: Adler, Richard W. "June 1990." Description based on title screen as viewed on October 20, 2009. DTIC Identifier(s): Computer Program Documentation, Subroutines, Electromagnetic Wave Propagation, Troposphere, Mathematical Models, FORTRAN. Author(s) subject terms: Tropospheric Duct Propagation, Computer Program Documentation. Includes bibliographical references (p. 139-140). Also available in print.
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Schoof, C. "Mathematical models of glacier sliding and drumlin formation." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249325.
Full textAbstract:
One of the central difficulties in many models of glacier and ice sheet flow lies in the prescription of boundary conditions at the bed. Often, processes which occur there dominate the evolution of the ice mass as they control the speed at which the ice is able to slide over the bed. In part I of this thesis, we study two complications to classical models of glacier and ice sheet sliding. First, we focus on the effect of cavity formation on the sliding of a glacier over an undeformable, impermeable bed. Our results do not support the widely used sliding law $u_b = C\tau_b^pN^{-q}$, but indicate that $\tau_b/N$ actually decreases with $u_b/N$ at high values of the latter, as suggested previously for simple periodic beds by Fowler (1986). The second problem studied is that of an ice stream whose motion is controlled by bed obstacles with wavelengths comparable to the thickness of ice. By contrast with classical sliding theory for ice of constant viscosity,the bulk flow velocity does not depend linearly on the driving stress. Indeed, the bulk flow velocity may even be a multi-valued function of driving stress and ice thickness. In the second part of the thesis, attention is turned to the formation of drumlins. The viscous till model of Hindmarsh (1998) and Fowler (2000) is analysed in some detail. It is shown that the model does not predict the formation of three-dimensional drumlins, but only that of two-dimensional features, which may be interpreted as Rogen moraines. A non-linear model allows the simulation of the predicted bedforms at finite amplitude. Results obtained indicate that the growth of bedforms invariably leads to cavitation. A model for travelling waves in the presence of cavitation is also developed, which shows that such travelling waves can indeed exist. Their shape is, however, unlike that of real bedforms, with a steep downstream face and no internal stratification. These results indicate that Hindmarsh and Fowler's model is probably not successful at describing the processes which lead to the formation of streamlined subglacial bedforms.
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Zhou, Qi Jessie. "Inferential methods for extreme value regression models /." *McMaster only, 2002.
Find full text
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Doustmohammadi, Ali. "Modeling and analysis of production systems." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/15776.
Full text
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Schliemann, Bernd F. "Analysis and modeling of the initiative tenet of current army operations doctrine." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/25091.
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Lin, Erlu, and 林尔路. "Analysis of dividend payments for insurance risk models with correlated aggregate claims." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40203992.
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Malone, Brett. "Multidisciplinary optimization in aircraft design using analysis technology models." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10102009-020042/.
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Ipperciel, David. "The performance of some new technical signals for investment timing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0028/NQ50190.pdf.
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Zhang, Dongxiao. "Conditional stochastic analysis of solute transport in heterogeneous geologic media." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186553.
Full textAbstract:
This dissertation develops an analytical-numerical approach to deterministically predict the space-time evolution of concentrations in heterogeneous geologic media conditioned on measurements of hydraulic conductivities (transmissivities) and/or hydraulic heads. Based on the new conditional Eulerian-Lagrangian transport theory by Neuman, we solve the conditional transport problem analytically at early time, and express it in pseudo-Fickian form at late time. The stochastically derived deterministic pseudo-Fickian mean concentration equation involves a conditional, space-time dependent dispersion tensor. The latter not only depends on properties of the medium and the velocity but also on the available information, and can be evaluated numerically along mean "particle" trajectories. The transport equation lends itself to accurate solution by standard Galerkin finite elements on a relatively coarse grid. This approach allows computing without using Monte Carlo simulation and explicitly the following: Concentration variance/covariance (uncertainty), origin of detected contaminant and associated uncertainty, mass flow rate across a "compliance surface", cumulative mass release and travel time probability distribution across this surface, uncertainty associated with the latter, second spatial moment of conditional mean plume about its center of mass, conditional mean second spatial moment of actual plume about its center of mass, conditional co-variance of plume center of mass, and effect of non-Gaussian velocity distribution. This approach can also account for uncertainty in initial mass and/or concentration when predicting the future evolution of a plume, whereas almost all existing stochastic models of solute transport assume the initial state to be known with certainty. We illustrate this approach by considering deterministic and uncertain instantaneous point and nonpoint sources in a two-dimensional domain with a mildly fluctuating, statistically homogeneous, lognormal transmissivity field. We take the unconditional mean velocity to be uniform, but allow conditioning on log transmissivity and hydraulic head data. Conditioning renders the velocity field statistically nonhomogeneous with reduced variances and correlation scales, renders the predicted plume irregular and non-Gaussian, and generally reduces both predictive dispersion and uncertainty.
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Chowdhury, Mohammed. "A Bayesian analysis of a conception model." Virtual Press, 2008. http://liblink.bsu.edu/uhtbin/catkey/1398705.
Full textAbstract:
Fecundability is regarded as one of the important parameters of fertility performance of the married women. Due to the complex nature of fecundability, we have attempted to estimate mean fecundability from the first conception interval. The first conception intervals have been obtained utilizing the data extracted from the 1999-2000 Bangladesh Demographic and Health Survey(BDHS). The purpose of the study is to estimate mean fecundability by various classical and non classical methods of estimation. Since the cohort of women is not homogeneous, we have attempted to estimate the mean natural fecundability from the Beta Distribution with parameters a and b. For the classical method, the parameters are estimated by the method of moments and method of maximum likelihood. For the non classical methods, standard, hierarchical, and empirical Bayes were used to estimate the mean fecundability. By using the Bangladesh Demographic and Health Survey(1999-2000) Data, the mean conception delay of the Bangladeshi women has been found to be 21.31 months after their first marriage and mean fecundability is 0.04692. This mean fecundability is computed as the reciprocal of mean conception delay. The theoretical arithmetic mean fecundabilities were found to be 0.058 and 0.066 employing the method of moments and method of maximum likelihood. The standard Bayes estimate of fecundability is 0.04696 while the Hierarchical and Empirical Bayes estimate of fecundability are 0.04694 and 0.04692. To compute the Hierarchical Bayes estimate, we used the Gibbs Sampler technique. In the case of Hierarchical Bayes method, we model the prior in terms of another random variable but in Empirical Bayes method, we estimate the parameter instead of attempting to model the parameter from the data. In this study, we have observed that the variation in mean fecundability is negligible whatever the methods of estimation be.Department of Mathematical Sciences
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Tabb, Jeremiah R. "Using wavelets and principle components analysis to model data from simulated sheet forming processes." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/10146.
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Myers, Cliff. "A fractal analysis of diffusion limited aggregation." PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/4047.
Full textAbstract:
A modified Witten-Sander algorithm was devised for the diffusion-limited aggregation process. The simulation and analysis were performed on a personal computer. The fractal dimension was determined by using various forms of a two-point density correlation function and by the radius of gyration. The results of computing the correlation function with square and circular windows were analyzed. The correlation function was further modified to include the edge from analysis and those results were compared to the fractal dimensions obtained from the whole aggregate. The fractal dimensions of 1.67 ± .01 and 1.75 ± .08 agree with the accepted values. Animation of the aggregation process elucidated the limited penetration into the interior and the zone of most active deposition at the exterior of the aggregate.
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Jung, Jungah. "Using generalized linear models with a mixed random component to analyze count data." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/JungJX2001.pdf.
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DITOLLA, ROBERT JOHN. "RANDOM VIBRATION ANALYSIS BY THE POWER SPECTRUM AND RESPONSE SPECTRUM METHODS (WHITE NOISE, FINITE-ELEMENT, VANMARCKE, DENSITY, NASTRAN)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183836.
Full textAbstract:
Determination of the stresses and displacements which occur in response to random excitations cannot be accomplished by traditional deterministic analysis methods. As the specification of the excitation and the response of the structure become more complex, solutions by direct, closed-form methods require extensive computations. Two methods are presented which can be used in the analysis of structures which are subjected to random excitations. The Power Spectrum Method is a procedure which determines the random vibration response of the structure based upon a frequency response analysis of a structural model. The Response Spectrum Method is a method which is based upon specified forces or displacements as a function of time. A derivation of each of the methods is presented and followed by comparisons of the results which were obtained for single and multiple-degree-of-freedom systems. Assumptions and limitations of the methods are discussed as well as their accuracy over ranges of frequency, damping and loading specification. As a direct application and comparison of the two methods, an analysis of the support system for the primary mirror of the Space Infrared Telescope Facility (SIRTF) has been performed. In addition, a method for the evaluation of the critical damping in a single-degree-of-freedom structure is demonstrated.