Source and channel coding using Fountain codes

The invention of Fountain codes is a major advance in the field of error correcting codes. The goal of this work is to study and develop algorithms for source and channel coding using a family of Fountain codes known as Raptor codes. From an asymptotic point of view, the best currently known sum-product decoding algorithm for non binary alphabets has a high complexity that limits its use in practice. For binary channels, sum-product decoding algorithms have been extensively studied and are known to perform well. In the first part of this work, we develop a decoding algorithm for binary codes on non-binary channels based on a combination of sum-product and maximum-likelihood decoding. We apply this algorithm to Raptor codes on both symmetric and non-symmetric channels. Our algorithm shows the best performance in terms of complexity and error rate per symbol for blocks of finite length for symmetric channels. Then, we examine the performance of Raptor codes under sum-product decoding when the transmission is taking place on piecewise stationary memoryless channels and on channels with memory corrupted by noise. We develop algorithms for joint estimation and detection while simultaneously employing expectation maximization to estimate the noise, and sum-product algorithm to correct errors. We also develop a hard decision algorithm for Raptor codes on piecewise stationary memoryless channels. Finally, we generalize our joint LT estimation-decoding algorithms for Markov-modulated channels. In the third part of this work, we develop compression algorithms using Raptor codes. More specifically we introduce a lossless text compression algorithm, obtaining in this way competitive results compared to the existing classical approaches. Moreover, we propose distributed source coding algorithms based on the paradigm proposed by Slepian and Wolf

Modified belief propagation decoders applied to non-CSS QLDGM codes.

Quantum technology is becoming increasingly popular, and big companies are starting to invest huge amounts of money to ensure they do not get left behind in this technological race. Presently, qubits and operational quantum channels may be thought of as far-fetched ideas, but in the future, quantum computing will be of critical importance. In this project, it is provided a concise overview of the basics of coding theory and how they can be used in the design of quantum computers. Specifically, Low Density Parity Check (LDPC) codes are focused, as they can be integrated within the stabilizer construction to build effective quantum codes. Following this, it is introduced the specifics of the quantum paradigm and present the most common family of quantum codes: stabilizer codes. Finally, it is explained the codes that have been used in this project, discussing what type of code they are and how they are designed. In this last section, it is also presented the ultimate goal of the project: using modified belief propagation decoders that had previously been tested for QLDPCs, for the proposed non-CSS QLDGM codes of this project

The structure of a supernova-dominated cloudy interstellar medium

The interstellar medium in our Galaxy is highly: inhomogeneous and is kept in a highly disturbed state by the large input of1 energy by supernova explosions. Under such circumstances, supernova remnants and interstellar clouds co-exist in a symbiotic relationship the parameters of each being determined by those of the other through the agency of the various interactions between them.I here develop a simple model of such a supernova dominated cloudy interstellar medium (SDC-ISM). Although based on the work of McKee and Ostriker (l977) it has been extended in several important respects. This model is subjected to an exhaustive parameter search in order to locate the boundaries of its domain of validity and to establish the sensitivity of the model to its various input parameters.This representation of the SDC-ISM is then combined with a simple model of the structure of the galaxy constructed within the framework of the spiral density wave theory. It is shown that the high temperature component of the ISM is ubiquitous both within the spiral arms and in the interarm region. It then follows that the strong spiral shock assumed can only be supported if quite restrictive conditions are imposed on the galactic supernova rate and the interstellar gas density.During this investigation the need for a more detailed description of the dynamical interaction between an SNR shock and an interstellar cloud was identified. To meet this need I have constructed a highly approximate but simpl * model of this process which is then used to explore the behaviour of a cloud exposed to conditions prevalent in the SDC-ISM. I find that having been shocked a cloud is rarely allowed sufficient time to return to pressure equili brium with its surroundings before encountering a second shock. The disruption of a cloud by its passage through a blast wave is found to be quite effective and the half life of clouds cannot greatly exceed the mean interval between shocks striking a given cloud

New Hampshire general court, journal of the house of representatives 1979 session, December 6, 1978 to June 28, 1979.

Titles and imprints vary; Some volumes include miscellaneous state documents and reports; Rules of the House of Representative

Malmsbury bluestone and quarries : Finding holes in history and heritage

Malmsbury bluestone was used widely from 1856 in buildings in Victoria, throughout Australia, and in New Zealand. It features in many structures listed on heritage registers, yet its presence is barely recognised. This largely results from the stone quarries, buildings and the men who laboured with it being absent from modern Australian historiography. The fame previously associated with the stone was lost when stone use for structural purposes, and the associated stone skills, declined; a situation exacerbated by poor recognition of the stone industry’s role in building our nation through heritage citations of structures. Inspired by E. P. Thompson, this thesis uses Critical Inquiry though microhistory and landscape analysis to regain the stone’s fame and rescue stoneworkers from the condescension of history. A detailed analysis of quarries, structures, the bluestone industry, and a rarely-attempted total reconstitution of the lives of 194 vital stoneworkers, reveals a valuable cultural heritage currently undervalued and at risk. Malmsbury stoneworkers came from diverse backgrounds but worked co-operatively to promote and sustain a local industry which supplied a nationally-vital building material, despite the absence of a regulatory framework to protect their lives and rights. Scientific methods document the geological properties of the stone and demonstrate how, in the absence of science, skilled stoneworkers nevertheless identified and worked a valuable resource. Modern science could however be used to test building stones in a non-destructive manner to determine the sources of currently unidentified building stones. This thesis significantly contributes to the limited discourse on the history and heritage of Australian stone use through the perspectives of cultural landscapes, labour history and built and cultural heritage. Malmsbury bluestone truly was the standard of excellence and, along with stoneworkers, warrants more extensive recognition in Australia’s Heritage registers.Doctor of Philosoph

Astrophysics in 2006

The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the universe) and others of which there are always many, like meteors and molecules, black holes and binaries.Comment: 244 pages, no figure

MIXING IT UP: THE IMPACT OF EPISODIC INTROGRESSION ON THE EVOLUTION OF HIGH-LATITUDE MESOCARNIVORES

At high latitudes, climatic oscillations have triggered repeated episodes of organismal divergence by geographically isolating populations. For terrestrial species, extended isolation in glacial refugia – ice-free regions that enable terrestrial species persistence through glacial maxima – is hypothesized to stimulate allopatric divergence. Alternatively, upon glacial recession, divergent populations expanded from independent glacial refugia and often contacted other diverging populations. In the absence of reproductive isolating mechanisms, this biogeographic process may trigger hybridization and ultimately, gene flow between divergent taxa. My dissertation research aims to understand how these episodic periods of isolation and contact have impacted the evolution of high latitude species. To understand the role of episodic isolation and gene flow on the evolution and diversification of high-latitude species, my dissertation integrates genetic, genomic, and morphometric characters across multiple high-latitude mesocarnivore mammals within the hyper-diverse Mustelidae family. Overall, I identified substantial cryptic diversity in the Arctic and highlight the complementary roles of glacial and interglacial cycles in the evolution and structuring of high latitude biota

Clemson Catalog, 1985-1986, Volume 60

https://tigerprints.clemson.edu/clemson_catalog/1173/thumbnail.jp

Proceedings of the 26th International Symposium on Theoretical Aspects of Computer Science (STACS'09)

The Symposium on Theoretical Aspects of Computer Science (STACS) is held alternately in France and in Germany. The conference of February 26-28, 2009, held in Freiburg, is the 26th in this series. Previous meetings took place in Paris (1984), Saarbr¨ucken (1985), Orsay (1986), Passau (1987), Bordeaux (1988), Paderborn (1989), Rouen (1990), Hamburg (1991), Cachan (1992), W¨urzburg (1993), Caen (1994), M¨unchen (1995), Grenoble (1996), L¨ubeck (1997), Paris (1998), Trier (1999), Lille (2000), Dresden (2001), Antibes (2002), Berlin (2003), Montpellier (2004), Stuttgart (2005), Marseille (2006), Aachen (2007), and Bordeaux (2008). ..