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 29 for “"tikhonov regularization"”.
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Extracting Ramachandran torsional angle distributions from 2D NMR data using Tikhonov regularization /
… stability of the inverse mapping is problematic. Tikhonov regularization is a well-known method of improving the stability of the inverse; in this work it is extended to use a new regularization functional based on the Laplacian rather than on the norm of the function itself. In this way, one …
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Source distribution analysis of magnetic microscopy maps of geological samples
… these problems, we have implemented several regularization techniques and constraints. Using synthetic, computationally generated measurements, our investigation demonstrates that Tikhonov regularization with a high pass filter matrix performs better than unregularized least square methods, …
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Everything old is new again : a fresh look at historical approaches in machine learning
… learning problems. We begin by considering Tikhonov regularization, a broad framework of schemes for binary classification. Tikhonov regularization attempts to find a function which simultaneously has small empirical loss on a training set and small norm in a Reproducing Kernel Hilbert …
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Recovering signals in physiological systems with large datasets
… noisy data. The first method is an extension of Tikhonov regularization to large-scale problems, using a sequential update approach. In the second method, we improve the conditioning of the problem by assuming that the input is uniform over a known time interval, and then we use a least-squares …
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A critical analysis of the 2H NMR data in chlorhexidine-containing model membranes
… bulk lipids in the membrane. The study used a Tikhonov-regularization-based numerical deconvolution technique (dePakeing) that allowed simultaneous determination of the order parameter and of the orientational distribution of domains in the powder sample, partially oriented by the external …
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Intelligent Monitoring of Powerline Vibrations - Sparse Sensing and Predictive Modeling Approach
… Dynamic Mode Decomposition (DMD) with Tikhonov regularization for stable reduced-order modeling, and estimation algorithms such as Kalman and particle filters for reconstructing full-system states from sparse observations. A pivoted QR decomposition method is employed to determine …
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Contributions to regularization theory and practice of certain nonlinear inverse problems
… inverse problems. The first part considers Tikhonov regularization for nonlinear ill-posed operator equations in Hilbert scales with oversmoothing penalties. Sufficient as well as necessary conditions to establish convergence are introduced and convergence rate results are given for various …
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Merging quadratic programming with kernel smoothing for automated cluster expansions of complex lattice Hamiltonians
… quadratic forms with the mathematical tool of Tikhonov regularization (kernel smoothing) for automated expansions of an arbitrary general physical property without compromising the underlying physics. Throughout the thesis we treat formation energy as the fundamental physical observable to …
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Wheel-rail contact force reconstruction using trackside measurements and inverse models
… state-space model of the track and solved using Tikhonov regularization with various regularization matrices. Rail velocity and displacement responses are used as inputs to reconstruct contact loads. The method is evaluated through twelve case studies involving a 40 mm wheel flat, exploring …
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Variational data assimilation for two interface problems
… the Beavers-Joseph interface condition. By using Tikhonov regularization and formulating the VDA into an optimization problem, we establish the existence, uniqueness and stability of the optimal solution for each concerned case. Based on weak formulations of the Parabolic Interface equation and …
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Development and Characterization of a Fast Neutron Imaging Telescope (FNIT) for 1--20 MeV Neutrons From the Sun and Nuclear Material
… for data inversion. We used zeroth-order Tikhonov regularization de-convolution algorithms to obtain the true neutron source spectrum for a given regularization (smoothing) parameter, lambda. Independent of the binning strategy, lambda is of order 10-6. We find that lambda +/- sigma …
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Methods for addressing noise and error in controlled source electromagnetic data
… modeling and a gradient-based approach with Tikhonov regularization for the inverse problem, this work shows that with a reasonable amount of noise, the distribution of both the in-phase and quadrature conductivities can be recovered in cross-well tomography. This information may be used in …
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Bayesian Analysis of Linear Inverse Problems with Applications in Economics and Finance
… The first one consists in adopting a Tikhonov regularization scheme in the construction of the posterior distribution so that I end up with a new object that I call regularized posterior distribution and that I guess it is solution of the inverse problem. The second approach consists …
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Development of GPR data analysis algorithms for predicting thin asphalt concrete overlay thickness and density
… reflected from thin AC overlays. Four types of regularization methods, including Tikhonov regularization and total variation regularization, were compared in terms of accuracy in estimating thin pavement layer thickness. The L-curve method was used to identify the appropriate regularization …
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Microwave remote sensing of water in the soil - plant system
… modeling - and thus retrieval - errors. A Tikhonov regularization approach is then introduced to allow retrieval of soil moisture in several profile layers by using statistics on the expected co-variation between soil moisture at different depths. The algorithm is tested using observations …
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Enhancement of unconventional oil and gas production forecasting using mechanistic-statistical modeling
… between wells. This thesis introduces Tikhonov regularization as a way of effectively sharing information across wells, cutting error in the earliest long-term productivity forecasts in half. Additionally, a spatiotemporal hierarchical Bayesian approach is developed that incorporates …
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Noncooperative static and dynamic games: addressing shared constraints and phase transitions
… in monotone regimes via a distributed iterative Tikhonov regularization (ITR) scheme. Notably, such schemes are single-timescale counterparts of standard Tikhonov regularization methods and involve updating the regularization parameter after every gradient step. Application of such techniques to …
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Fast superresolution based on a network structure trained using sparse coding
… that includes the square of the L2 norm and a regularization term containing the L1 norm of the sparse vector. This sets up a regularized least squares solution. The L1 norm is preferred because it promotes the sparseness of the solution. The L0 norm term in the regularization parameter may …
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Optimal Control for an Impedance Boundary Value Problem
… within the framework of the minimization of a Tikhonov functional. In particular, questions of the existence of an optimal solution and the derivation of the optimality conditions will be addressed.
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