Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"Nonlinear methods."”.
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Nonlinear methods for solving the diffusion equation.
Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering.
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Surface characterisation with nonlinear methods based on scale analysis
In this thesis we develop methods for the analysis of surfaces whose formation processes are not exactly describable. We demonstrate the methods for two examples. The first is a metal surface generated by the processing with a laser device, the second is the electron microscopy image of a cross …
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Nonlinear Methods in the Study of Singular Partial Differential Equations
Nonlinear singular partial differential equations arise naturally when studying models from such areas as Riemannian geometry, applied probability, mathematical physics and biology. The purpose of this thesis is to develop analytical methods to investigate a large class of nonlinear elliptic PDEs …
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Characterization of hypertension through multivariate analysis utilizing linear and nonlinear methods
Analysis of blood pressure by nonlinear methods is vastly underutilized in current research. As such, 24-hour ambulatory blood pressure data from a small cohort of borderline hypertensive and normotensive subjects were analyzed using linear and nonlinear methods. Data were collected and provided by …
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Electrocardiogram-based detection of heart pathologies using nonlinear methods and machine learning
Το Ηλεκτροκαρδιογράφημα (ΗΚΓ) παραμένει το πλέον ευρέως χρησιμοποιούμενο, μη επεμβατικό διαγνωστικό εργαλείο στην καρδιολογία· ωστόσο, η ακριβής ερμηνεία του δυσχεραίνεται από τεχνουργήματα (artifacts) σήματος, θόρυβο και διακύμανση μεταξύ παρατηρητών. Τα αυτοματοποιημένα συστήματα ανάλυσης …
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The use of linear and nonlinear methods for evaluating balance on collegiate men’s and women’s ice hockey teams throughout a season
… mean velocity, and total excursion) and nonlinear (approximate entropy) measures were used to interpret force plate data. Linear and nonlinear measures both showed significant main effects of time. Monthly testing throughout the season demonstrated decreases in mean values for all …
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Large-signal tools for power electronics: State space analysis and averaging theory
This thesis explores the application of nonlinear methods to the practical problems of switching power converter analysis and design. Based on switching algebra, a formalism for large-signal component modeling is developed. The governing equation is formulated for a general class of mixed-mode …
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The application of advanced hydrodynamic analyses in ship design
… has been conducted towards the prediction of nonlinear wave-induced motions and loads in the time domain. Seakeeping analysis has traditionally been incorporated late in the design process, using parametrics and two-dimensional linear strip theory methods in the frequency domain. Model …
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Observing the unfolding transition of [beta]-hairpin peptides with nonlinear infrared spectroscopy
… it to structural features. Three spectroscopic methods are used to probe the amide I band: Fourier transform infrared (FTIR) spectroscopy, two-dimensional infrared (2D IR) spectroscopy, and dispersed vibrational echo (DVE) spectroscopy. 2D IR and DVE spectroscopy are 3rd order-nonlinear methods …
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Subsystem Design in Aircraft Power Distribution Systems using Optimization
… to a simple mechanical structure. Linear and nonlinear methods to study subsystem interaction and stability are studied in Part III. A multivariable impedance ratio criterion applicable to three phase systems is proposed. Bifurcation methods are used to obtain global stability characteristics …
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Signal processing and image restoration techniques for two-dimensional eddy current nondestructive evaluation
… a comprehensive study on the forward modeling methods, signal processing techniques, and image restoration techniques for two-dimensional eddy current nondestructive evaluation. The basic physical forward method adopted in this study is the volume integral method. We have applied this model to …
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Current account deficits and sustainability: evidence from South Africa
… one or the other. Third, this study considers nonlinear methods in its evaluation, and to our knowledge, all studies evaluating South Africa, and most global literature, rely on linear methods. Lastly, we use three specifications of the current account in the cointegration approach for robust …
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Nonlinear network vector autoregression
… many important macroeconomic time series exhibit nonlinear characteristics. If this non-linear feature is ignored, the conclusion is likely to be wrong by only using linear analysis. Therefore, it is necessary to expand the linear model and propose nonlinear methods. Economic theory also shows …
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Exploring nonlinear regression methods, with application to association studies
The field of nonlinear regression is a long way from reaching a consensus. Once a method decides to explore nonlinear combinations of predictors, a number of questions are raised, such as what nonlinear combinations to permit and how best to search the resulting model space. Genetic Association …
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Robust Kalman Filters Using Generalized Maximum Likelihood-Type Estimators
Estimation methods such as the Kalman filter identify best state estimates based on certain optimality criteria using a model of the system and the observations. A common assumption underlying the estimation is that the noise is Gaussian. In practical systems though, one quite frequently encounters …
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STRUCTURE-OPTIMIZED AND ORDER-PRESERVING METHODS FOR ADVECTION AND TIME STEPPING
… fundamental shortcomings in computational methods for differential equations by developing novel high-order accurate numerical schemes that can apply to multi-physics or multi-scale problems. Motivated by the need for numerical methods with long-time accurate solutions in complex …
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Exploring the dimensionality of speech using manifold learning and dimensionality reduction methods
… sounds. A number of dimensionality reduction methods capable of discovering such underlying structure have previously been applied to speech. However, if speech lies on a manifold nonlinearly embedded in high-dimensional space, as has been proposed in the past, classic linear dimensionality …
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Application of nonlinear dimensionality reduction to climate data for prediction
… found may be summarised as follows: 1. Linear methods are not suitable for characterising the dimensionality of the sea surface temperature in the tropical Pacific Ocean. Therefore they do not help to separate the oscillations by themselves. Instead, nonlinear methods of dimensionality …
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Modelling human complex traits with regression and neural-network based methods
… unit computing farms and neural-network based methods, together with large biobank-scale data sets, such as the UK Biobank which offers a sample size of ~500K, this has been changing. These developments offer opportunities for the development of novel approaches that could provide insights into …
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Market Efficiency of African Stock Markets
… been mixed. This problem might be due to the methods used in the analyses. First, most of the methods used were linear in nature although the data generating process of stock market data is nonlinear and hence nonlinear methods maybe more appropriate in its analysis. Also these linear methods …
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