Download or read book Smoothed NUV Priors for Imaging and Beyond written by Boxiao Ma and published by BoD – Books on Demand. This book was released on 2022-05-10 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many problems in imaging need to be guided with effective priors or reg- ularizations for different reasons. A great variety of regularizations have been proposed that have substantially improved computational imaging and driven the area to a whole new level. The most famous and widely applied among them is L1-regularization and its variations, including total variation (TV) regularization in particular. This thesis presents an alternative class of regularizations for imaging using normal priors with unknown variance (NUV), which produce sharp edges and few staircase artifacts. While many regularizations (includ- ing TV) prefer piecewise constant images, which leads to staricasing, the smoothed-NUV (SNUV) priors have a convex-concave structure and thus prefer piecewise smooth images. We argue that "piecewise smooth" is a more realistic assumption compared to "piecewise constant" and is crucial for good imaging results.
Download or read book Composite NUV Priors and Applications written by Raphael Urs Keusch and published by BoD – Books on Demand. This book was released on 2022-08-19 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: Normal with unknown variance (NUV) priors are a central idea of sparse Bayesian learning and allow variational representations of non-Gaussian priors. More specifically, such variational representations can be seen as parameterized Gaussians, wherein the parameters are generally unknown. The advantage is apparent: for fixed parameters, NUV priors are Gaussian, and hence computationally compatible with Gaussian models. Moreover, working with (linear-)Gaussian models is particularly attractive since the Gaussian distribution is closed under affine transformations, marginalization, and conditioning. Interestingly, the variational representation proves to be rather universal than restrictive: many common sparsity-promoting priors (among them, in particular, the Laplace prior) can be represented in this manner. In estimation problems, parameters or variables of the underlying model are often subject to constraints (e.g., discrete-level constraints). Such constraints cannot adequately be represented by linear-Gaussian models and generally require special treatment. To handle such constraints within a linear-Gaussian setting, we extend the idea of NUV priors beyond its original use for sparsity. In particular, we study compositions of existing NUV priors, referred to as composite NUV priors, and show that many commonly used model constraints can be represented in this way.
Download or read book Using Local State Space Model Approximation for Fundamental Signal Analysis Tasks written by Elizabeth Ren and published by BoD – Books on Demand. This book was released on 2023-05-26 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: With increasing availability of computation power, digital signal analysis algorithms have the potential of evolving from the common framewise operational method to samplewise operations which offer more precision in time. This thesis discusses a set of methods with samplewise operations: local signal approximation via Recursive Least Squares (RLS) where a mathematical model is fit to the signal within a sliding window at each sample. Thereby both the signal models and cost windows are generated by Autonomous Linear State Space Models (ALSSMs). The modeling capability of ALSSMs is vast, as they can model exponentials, polynomials and sinusoidal functions as well as any linear and multiplicative combination thereof. The fitting method offers efficient recursions, subsample precision by way of the signal model and additional goodness of fit measures based on the recursively computed fitting cost. Classical methods such as standard Savitzky-Golay (SG) smoothing filters and the Short-Time Fourier Transform (STFT) are united under a common framework. First, we complete the existing framework. The ALSSM parameterization and RLS recursions are provided for a general function. The solution of the fit parameters for different constraint problems are reviewed. Moreover, feature extraction from both the fit parameters and the cost is detailed as well as examples of their use. In particular, we introduce terminology to analyze the fitting problem from the perspective of projection to a local Hilbert space and as a linear filter. Analytical rules are given for computation of the equivalent filter response and the steady-state precision matrix of the cost. After establishing the local approximation framework, we further discuss two classes of signal models in particular, namely polynomial and sinusoidal functions. The signal models are complementary, as by nature, polynomials are suited for time-domain description of signals while sinusoids are suited for the frequency-domain. For local approximation of polynomials, we derive analytical expressions for the steady-state covariance matrix and the linear filter of the coefficients based on the theory of orthogonal polynomial bases. We then discuss the fundamental application of smoothing filters based on local polynomial approximation. We generalize standard SG filters to any ALSSM window and introduce a novel class of smoothing filters based on polynomial fitting to running sums.
Download or read book A New Perspective on Memorization in Recurrent Networks of Spiking Neurons written by Patrick Murer and published by BoD – Books on Demand. This book was released on 2022-05-13 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies the capability of spiking recurrent neural network models to memorize dynamical pulse patterns (or firing signals). In the first part, discrete-time firing signals (or firing sequences) are considered. A recurrent network model, consisting of neurons with bounded disturbance, is introduced to analyze (simple) local learning. Two modes of learning/memorization are considered: The first mode is strictly online, with a single pass through the data, while the second mode uses multiple passes through the data. In both modes, the learning is strictly local (quasi-Hebbian): At any given time step, only the weights between the neurons firing (or supposed to be firing) at the previous time step and those firing (or supposed to be firing) at the present time step are modified. The main result is an upper bound on the probability that the single-pass memorization is not perfect. It follows that the memorization capacity in this mode asymptotically scales like that of the classical Hopfield model (which, in contrast, memorizes static patterns). However, multiple-rounds memorization is shown to achieve a higher capacity with an asymptotically nonvanishing number of bits per connection/synapse. These mathematical findings may be helpful for understanding the functionality of short-term memory and long-term memory in neuroscience. In the second part, firing signals in continuous-time are studied. It is shown how firing signals, containing firings only on a regular time grid, can be (robustly) memorized with a recurrent network model. In principle, the corresponding weights are obtained by supervised (quasi-Hebbian) multi-pass learning. The asymptotic memorization capacity is a nonvanishing number measured in bits per connection/synapse as its discrete-time analogon. Furthermore, the timing robustness of the memorized firing signals is investigated for different disturbance models. The regime of disturbances, where the relative occurrence-time of the firings is preserved over a long time span, is elaborated for the various disturbance models. The proposed models have the potential for energy efficient self-timed neuromorphic hardware implementations.
Download or read book Galaxy Interactions at Low and High Redshift written by J.E. Barnes and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings offer professional astronomers an overview of the rapidly advancing subject of galaxy interactions at low and high redshifts. The symposium gave participants an exciting glimpse of a developing synthesis highlighting galactic encounters and their role in the history of the Universe.
Download or read book Multimedia written by Tay Vaughan and published by Osborne Publishing. This book was released on 1996 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thoroughly updated for newnbsp;breakthroughs in multimedia nbsp; The internationally bestselling Multimedia: Making it Work has been fully revised and expanded to cover the latest technological advances in multimedia. You will learn to plan and manage multimedia projects, from dynamic CD-ROMs and DVDs to professional websites. Each chapter includes step-by-step instructions, full-color illustrations and screenshots, self-quizzes, and hands-on projects. nbsp;
Download or read book Transiting Exoplanets written by Carole A. Haswell and published by Cambridge University Press. This book was released on 2010-07-29 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: The methods used in the detection and characterisation of exoplanets are presented in this unique textbook for advanced undergraduates.
Download or read book The Physics and Evolution of Active Galactic Nuclei written by Hagai Netzer and published by Cambridge University Press. This book was released on 2013-09-16 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive introduction to the theory underpinning our study of active galactic nuclei and the ways we observe them.
Download or read book Defects in Semiconductors written by and published by Academic Press. This book was released on 2015-06-08 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoretical paths. - Expert contributors - Reviews of the most important recent literature - Clear illustrations - A broad view, including examination of defects in different semiconductors
Download or read book Mathematical Systems Theory in Biology Communications Computation and Finance written by Joachim Rosenthal and published by Springer Science & Business Media. This book was released on 2003-09-02 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains survey and research articles by some of the leading researchers in mathematical systems theory - a vibrant research area in its own right. Many authors have taken special care that their articles are self-contained and accessible also to non-specialists.
Download or read book Climate Change and Impacts in the Pacific written by Lalit Kumar and published by Springer Nature. This book was released on 2020-01-31 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: This edited volume addresses the impacts of climate change on Pacific islands, and presents databases and indexes for assessing and adapting to island vulnerabilities. By analyzing susceptibility variables, developing comprehensive vulnerability indexes, and applying GIS techniques, the book's authors demonstrate the particular issues presented by climate change in the islands of the Pacific region, and how these issues may be managed to preserve and improve biodiversity and human livelihoods. The book first introduces the issues specific to island communities, such as high emissions impacts, and discusses the importance of the lithological traits of Pacific islands and how these physical factors relate to climate change impacts. From here, the book aims to analyze the various vulnerabilities of different island sectors, and to formulate a susceptibility index from these variables to be used by government and planning agencies for relief prioritization. Such variables include tropical cyclones, built infrastructures, proximity to coastal areas, agriculture, fisheries and marine resources, groundwater availability, biodiversity, and economic impacts on industries such as tourism. Through the categorization and indexing of these variables, human and physical adaptation measures are proposed, and support solutions are offered to aid the inhabitants of affected island countries. This book is intended for policy makers, academics, and climate change researchers, particularly those dealing with climate change impacts on small islands.
Download or read book New Quests in Stellar Astrophysics II written by Miguel Chavez Dagostino and published by Springer Science & Business Media. This book was released on 2009-02-27 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an up-to-date collection of reviews and contributed articles in the field of ultraviolet astronomy. Its content has been mainly motivated by the recent access to the rest frame UV light of distant red galaxies, gained through large optical facilities. This driveway has derived in a renewed interest on the stars that presumably dominate or have important effects on the integrated UV properties of evolved systems of the nearby and faraway Universe. The topics included in this volume extend from the fresh spectroscopic analyses of high redshift early-type galaxies observed with the 8-10m class telescopes to the fundamental outcomes from various satellites, from the long-lived International Ultraviolet Explorer to current facilities, such as the Galaxy Evolution Explorer. This is one of the few volumes published in recent years devoted to UV astronomical research and the only one dedicated to the properties of evolved stellar populations at these wavelengths. This contemporary panorama will be an invaluable resource in the preparation of the next planned space missions, such as the World Space Observatory and the Ultraviolet Imaging Telescope.
Download or read book Exoplanet Science Strategy written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2019-01-17 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: The past decade has delivered remarkable discoveries in the study of exoplanets. Hand-in-hand with these advances, a theoretical understanding of the myriad of processes that dictate the formation and evolution of planets has matured, spurred on by the avalanche of unexpected discoveries. Appreciation of the factors that make a planet hospitable to life has grown in sophistication, as has understanding of the context for biosignatures, the remotely detectable aspects of a planet's atmosphere or surface that reveal the presence of life. Exoplanet Science Strategy highlights strategic priorities for large, coordinated efforts that will support the scientific goals of the broad exoplanet science community. This report outlines a strategic plan that will answer lingering questions through a combination of large, ambitious community-supported efforts and support for diverse, creative, community-driven investigator research.
Download or read book The X ray Background written by Xavier Barcons and published by Cambridge University Press. This book was released on 1992-07-31 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the current observational knowledge and understanding of the cosmic X-ray background.
Download or read book Astrophotonics written by Stefano Minardi and published by VCH. This book was released on 2012-04-04 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by well-known scientists in the field with vast experience in teaching astrophotonics, this is the first book to bridge astronomy and photonics for the benefit of developing new astronomical instrumentation. The textbook is clearly structured and covers four main methods relevant to observational astronomy: adaptive optics, photometry, interferometry and spectroscopy. It follows a progressive didactical path in photonics, starting from fundamentals of wave- and micro-optics and developing step-by-step the formalisms required for the treatment of optical multilayers, fiber optics and diffraction/holographic gratings. This approach allows students with a physics/engineering background to learn about the problematic of observational astronomy, while, conversely, students of astronomy are exposed to topics in modern photonics. Each chapter is divided into three main sections devoted to the discussion of astronomical concepts required to size an instrument designed for the particular method, the photonic concepts that most suit that instrument, and an analysis of existing, related photonic instruments. A set of exercises and a bibliography complete each chapter. Appendices include a short review of fundamentals of wave optics and photon detectors, plus an overview of project design and management using a real-life example of an astronomical instrumentation project. With its review of the latest instrumentation and techniques, this is invaluable for graduate and post-graduate students in astronomy, physics and optical engineering.
Download or read book Outskirts of Galaxies written by Johan H. Knapen and published by Springer. This book was released on 2017-07-09 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book consists of invited reviews written by world-renowned experts on the subject of the outskirts of galaxies, an upcoming field which has been understudied so far. These regions are faint and hard to observe, yet hide a tremendous amount of information on the origin and early evolution of galaxies. They thus allow astronomers to address some of the most topical problems, such as gaseous and satellite accretion, radial migration, and merging. The book is published in conjunction with the celebration of the end of the four-year DAGAL project, an EU-funded initial training network, and with a major international conference on the topic held in March 2016 in Toledo. It thus reflects not only the views of the experts, but also the scientific discussions and progress achieved during the project and the meeting. The reviews in the book describe the most modern observations of the outer regions of our own Galaxy, and of galaxies in the local and high-redshift Universe. They tackle disks, haloes, streams, and accretion as observed through deep imaging and spectroscopy, and guide the reader through the various formation and evolution scenarios for galaxies. The reviews focus on the major open questions in the field, and explore how they can be tackled in the future. This book provides a unique entry point into the field for graduate students and non-specialists, and serves as a reference work for researchers in this exciting new field.
Download or read book Image Analysis Sediments and Paleoenvironments written by Pierre Francus and published by Springer Science & Business Media. This book was released on 2007-01-19 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a guide to imaging techniques for sedimentologists, paleolimnologists, paleoceanographers and microscopists involved in paleoenvironmental reconstruction. Case studies illustrate the range of information obtainable from different sediments (marine, lacustrine, aeolian) and different types of samples (cores, embedded blocks, microscopic slides) using different regions of the electromagnetic spectrum (visible, UV, IR, X-ray). Includes comprehensive protocols, guidelines, and recommendations for the use of low cost image analysis techniques.
