• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 134
  • 16
  • 14
  • 7
  • 6
  • 6
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 243
  • 94
  • 48
  • 48
  • 37
  • 28
  • 28
  • 24
  • 22
  • 20
  • 18
  • 18
  • 17
  • 17
  • 17
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

[en] FOUNTAIN CODES AND OTHER CHANNEL CODING SCHEMES FOR PROTECTION OF TRANSPORT STREAMS OVER IP NETWORKS WITH PACKET ERASURE / [pt] CÓDIGOS FONTANAIS E OUTROS ESQUEMAS DE CODIFICAÇÃO DE CANAL PARA PROTEÇÃO DE TRANSPORT STREAMS EM REDES IP COM APAGAMENTO DE PACOTES

CLAUDIO ALEJANDRO SZABAS 06 July 2011 (has links)
[pt] Há, nos dias atuais, uma crescente demanda pelo transporte de video sobre IP, i.e., para distribuição de conteúdo pela Internet, por serviços de IPTV em definição padrão e em alta definição e, mesmo para uso interno nas redes de emissoras tradicionais de televisão, que transportam contribuições de elevada qualidade para seus programas. Em tais aplicações, o conteúdo dos programas é transportado usando MPEG-2 ou MPEG-4, sob a forma de MPEG-2 Transport Streams, encapsulados com protocolos tais como RTP, UDP e IP. As redes IP, que são modelizadas como Redes com Apagamento de Pacotes (PEC) não foram, no entanto, concebidas para o transporte de mídias em tempo real, esbarra portanto em problemas comuns como perdas de pacotes e jitter, gerando perturbações que se refletem na recepção do conteúdo. Os métodos tradicionais para superar estas dificuldades, como por exemplo, os que se baseiam em retransmissões usando protocolos ARQ (Automatic Repeat on Request), não são uma solução eficiente para proteger a transmissão de multimídia em tempo real. A proteção de multimídia transmitida em tempo real via IP recorre, neste caso, aos códigos para canal. Há códigos para canal recomendados em RFC s e Padrões, usados amplamente pelos fabricantes de equipamento. Os modernos Códigos Fontanais, possuem características atraentes para o transporte de conteúdos multimídia em tempo real. Neste trabalho, simulações são realizadas, onde o conteúdo encapsulado em Transport Stream, é protegido com Códigos Fontanais antes do encapsulamento para o envio através da rede. A título de comparação, o experimento é realizado também usando outros códigos para canal recomendados. Para realizar a comparação são usadas medições padronizadas do Transport Stream, medições objetivas como artefatos de blocagem e finalmente uma análise subjetiva do conteúdo recebido é usada. O trabalho conclui com a proposta de um Codificador de canal adaptável para Transport Stream. / [en] There is a growing demand for the transport of video over IP today, i.e., for content distribution over the Internet, IPTV services in Standard and High Definition, or even inside traditional broadcasters networks, transporting broadcast quality contributions to the main program. In such applications, the source encoded MPEG-2 or -4 content is transported in the form of MPEG-2 Transport Streams, encapsulated over network protocols. However, IP networks, which can be modeled as Packet Erasure Networks (PEC), were not originally designed for the transport of real time media. There are problems, such as packet drops and jitter, which generate severe impairments in the content that is decoded at the reception. Traditional methods for overcoming these problems, as for example retransmissions performed by Automatic Repeat Request (ARQ) protocols, are not suitable for real-time multimedia protection. Channel coding is the solution of choice for protecting real-time multimedia over IP. There are channel coding schemes specified in open recommendations and Standards, widely adopted by equipment vendors today. Fountain Codes present very attractive characteristics for the transport of real-time multimedia. In the present work, simulations with a Fountain code, protecting Transport Stream contents prior to network encapsulation, are presented. The experiment if repeated with other channel coding techniques commonly employed today. In order to analyze the decoded contents and obtain comparative results, standardized Transport Stream measurements, objective Blocking Artifacts measurements and subjective analysis of the decoded samples are employed. This work is concluded with the proposal of a Transport Stream Adaptive channel encoder, that is explained in Appendix-B.
92

Implementação em VHDL de uma arquitetura paralela de um código de Reed-Solomon aplicado a Redes OTN / VHDL implementation of parallel architecture of the Reed-Solomon code for OTN networks

Salvador, Arley Henrique, 1979- 27 August 2018 (has links)
Orientadores: Dalton Soares Arantes, Júlio César Rodrigues Fernandes de Oliveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-27T18:41:53Z (GMT). No. of bitstreams: 1 Salvador_ArleyHenrique_M.pdf: 3542397 bytes, checksum: 0847a4269c07c0969394ba0b40491987 (MD5) Previous issue date: 2015 / Resumo: Este trabalho apresenta a implementação de uma arquitetura paralela de um código corretor de erros para aplicações em redes ópticas que utilizam a técnica Foward Error Correction (FEC). O algoritmo FEC especificamente tratado neste trabalho é o Reed-Solomon, que é destinado principalmente a sistemas que sofrem influência causada por erros em rajadas somados ao sinal durante a transmissão, o que o torna adequado para transmissões ópticas. São expostas estruturas seriais de codificador e decodificador FEC e as etapas para convertê-las para uma estrutura paralela. Após descrever as etapas de conversão de uma estrutura serial para paralela é apresentada a estrutura do codificador/decodficador FEC Reed-Solomon RS(255,239) com estrutura paralela para operar em redes ópticas a uma taxa de 100 Gbit/s. Esta descrição exemplificativa é o objetivo principal deste trabalho. A implementação paralela do FEC oferece como vantagem a capacidade de processar os dados de forma rápida, permitindo o emprego desta solução em sistemas com altas taxas de dados. Foi elaborado um ambiente de testes com uma aplicação em redes de transporte óptico, ou Optical Transport Network (OTN). Esta funcionalidade consiste de um Transponder, que tem a função de mapear um cliente de 100 Gigabits Ethernet dentro de uma estrutura de quadro destinado a transmissão de dados em redes ópticas. Deste modo, pôde-se comprovar os resultados e o desempenho da estrutura proposta / Abstract: This paper presents the implementation of a parallel architecture error-correcting code for optical applications that uses the Forward Error Correction (FEC) technique. The FEC algorithm specifically addressed in this work is applied to the Reed-Solomon, which is mainly intended for systems that are harmed by burst errors, which makes it suitable for optical transmissions. A serial FEC encoder/decoder structure and the steps to convert it to a parallel approach are addressed in this work. An example of method that generates an encoder/decoder for a RS(255,239) Reed-Solomon code with parallel structure, able to operate at 100 Gbit/s data rate in optical networks, is also presented. The parallel implementation offers higher FEC processing speeds to handle higher throughputs. A test environment was designed with an application in optical transport networks (OTN). This feature consists a transponder which maps a 100 Gigabit Ethernet client inside an OTN frame structure. With this setup the expected results for the proposed FEC circuitry could be experimentally verified / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica
93

Faktorizacija polinoma dve promenljive sa celobrojnim koeficijentima pomoću Newton-ovog poligona i primena u dekodiranju nekih klasa Reed – Solomon kodova / Factoring bivariate polynomials with integer coefficients via Newton polygon and its application in decoding of some classes of Reed – Solomon codes

Pavkov Ivan 29 September 2107 (has links)
<p>Predmet istraživanja doktorske disertacije je faktorizacija polinoma dve promenljive sa celobrojnim koeficijentima pomoću njima pridruženih Newton-ovih poligona. Formalizacija potrebnog i dovoljnog uslova za postojanje netrivijalne faktorizacije polinoma dve promenljive sa celobrojnim koeficijentima omogućava konstrukciju efektivnog algoritma za faktorizaciju. Konačno, dobijeni teorijski rezultati su primenjeni na dekodiranje jedne klase Reed &ndash; Solomon kodova, miksa dve kodne reči.</p> / <p>The research subject of the thesis is factorization of bivariate polynomials with integer coefficients via associated Newton polygons. Formalization of the necessary and sufficient condition for the existence of a non &ndash; trivial factorization of an arbitrary bivariate polynomial with integer coefficients obtains theoretical basis for construction of an effective factorization algorithm. Finally, these theoretical results are applied in decoding special class of Reed &ndash; Solomon codewords, mixture of two codewords.</p>
94

NEW TELEMETRY HARDWARE FOR THE DEEP SPACE NETWORK TELEMETRY PROCESSOR SYSTEM

Puri, Amit, Ozkan, Siragan, Schaefer, Peter, Anderson, Bob, Williams, Mike 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes the new Telemetry Processor Hardware (TPH) that Avtec Systems has developed for the Deep Space Network (DSN) Telemetry Processor (TLP) system. Avtec is providing the Telemetry Processor Hardware to RTLogic! for integration into the Telemetry Processor system. The Deep Space Network (DSN) is an international network of antennas that supports interplanetary spacecraft missions for exploration of the solar system and the universe. The Jet Propulsion Laboratory manages the DSN for NASA. The TLP system provides the capability to acquire, process, decode and distribute deep space probe and Earth orbiter telemetry data. The new TLP systems will be deployed at each of the three deep-space communications facilities placed approximately 120 degrees apart around the world: at Goldstone, California; near Madrid, Spain; and near Canberra, Australia. The Telemetry Processor Hardware (TPH) supports both CCSDS and TDM telemetry data formats. The TPH performs the following processing steps: soft-symbol input selection and measurement; convolutional decoding; routing to external decoders; time tagging; frame synchronization; derandomization; and Reed-Solomon decoding. The TPH consists of a VME Viterbi Decoder/MCD III Interface board (VM-7001) and a PCI-mezzanine Frame Synchronizer/Reed-Solomon Decoder (PMC- 6130-J) board. The new Telemetry Processor Hardware is implemented using the latest Field Programmable Gate Array (FPGA) technology to provide the density and speed to meet the current requirements as well as the flexibility to accommodate processing enhancements in the future.
95

Telemetering Method Using Delayed Frame Time Diversity (DFTD) and Reed-Solomon Code

Koh, Kwang-Ryul, Lee, Sang-Bum, Kim, Whan-Woo 10 1900 (has links)
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / This paper proposes a telemetering method consisting of delayed frame time diversity (DFTD) as the inner code and Reed-Solomon (RS) code as the outer code. DFTD is used to transmit a real-time frame together with a time-delayed frame which was saved in the memory during a defined period. The RS code is serially concatenated with DFTD. This method was applied to the design of telemetry units that have been used for over ten flight tests. The data results of the flight test for four cases with no applied code, with DFTD only, with the RS code only, and with both DFTD and the RS code are used to compare the number of error frames. The results also show that the proposed method is very useful and applicable to telemetry applications in a communication environment with a deep fade.
96

MULTIVARIATE LIST DECODING OF EVALUATION CODES WITH A GRÖBNER BASIS PERSPECTIVE

Busse, Philip 01 January 2008 (has links)
Please download dissertation to view abstract.
97

Bernard of Clairvaux on the Song of Songs: a Contemporary Encounter With Contemplative Aspirations

Mols, Michael John 08 1900 (has links)
Recent scholarship in biblical interpretation has remained suspicious of the "allegorical" approach to scripture, presumed as common to Medieval Christianity, and Bernard of Clairvaux is often acknowledged as paradigmatic of contemplative exegesis. Bernard's Sermons on the Song of Songs is often alleged to be an ultimate example of the dangers of monastic "allegorizing," in that such an approach lacks any consistency of method and maintains an ideological stance that is suspicious of and ultimately rejects the nature of bodily existence. This thesis counters these claims by utilizing the work of contemporary medievalists, instead of contemporary biblical exegetes, as a lens in a close reading of Bernard's Sermones Super Cantica, as well as his textual interaction with Peter Abelard and Peter the Venerable. This thesis suggests that Bernard is consistent in his method of performative reading and holds bodily existence as vital to the monastic and broader Christian way of life.
98

The power of legitimacy : local cooperation and the effectiveness of peace operations

Whalan, Jeni January 2010 (has links)
This thesis investigates how peace operations work. It contributes to the larger study of peace operation effectiveness by analysing the processes through which these institutions influence local actors in postconflict societies. Looking beyond traditional concerns with mandates and resources, it aims to understand how a peace operation seeks to achieve its goals, focusing on why local populations might cooperate with or obstruct its activities. The thesis draws on theories of social power, compliance and legitimation to answer four central questions: what power do peace operations have to achieve their objectives? From where do peace operations derive power? How do local perceptions of an operation enable or constrain its effectiveness? How are peace operations legitimised at the local level, and with what effect? It begins by critically reviewing the academic literature, arguing that existing approaches are unable to account for important dimensions of peace operation effectiveness because they neglect the local setting in which operations pursue their goals, and the extent to which the achievement of those goals requires local cooperation. It then develops an analytical framework to examine the processes of coercion, inducement and legitimacy through which peace operations seek to shape the decisions and actions of local actors. This power-legitimacy framework is applied to study the effectiveness of the United Nations Transitional Authority in Cambodia (UNTAC) and the Regional Assistance Mission in Solomon Islands (RAMSI). By comparing variation in local cooperation between and within these cases, the thesis shows that the way a peace operation is locally perceived is an important but often overlooked determinant of its effectiveness. In particular, when local actors perceive a peace operation to be legitimate, they are more likely to behave in ways that assist the operation to achieve its goals. The thesis concludes by discussing the implications of this finding for the future study and practice of peace operations.
99

Toni Morrison’s Depiction of Beauty Standards in Relation to Class, Politics of Respectability, and Consumerism in Song of Solomon

Jensen, Karen 20 December 2013 (has links)
In Song of Solomon, published during a transitional moment in the history of U.S. feminism, Toni Morrison portrays the destructive forces of hegemonic female beauty standards, materialism, and consumerism in a Midwestern African-American community from the 1930s to the 1960s. She reveals a hierarchy in which men define standards of beauty and respectability that enforce white bourgeois ideals. Focusing on five female characters, this thesis examines this hierarchy; the agents who maintain it; and the ways in which it affects female characters who accept and/or reject it. While one of the characters, Hagar, perishes in her attempt to live up to normative beauty standards, her cousin Corinthians is liberated when she leaves her oppressive father and moves in with a working class male partner. Morrison thus creates a viable alternative to strict adherence to materialist values, while representing the destructive force of oppressive beauty norms and standards of respectability.
100

Correcting bursts of adjacent deletions by adapting product codes

25 March 2015 (has links)
M.Ing. (Electrical and Electronic Engineering) / In this study, the problem of correcting burst of adjacent deletions by adapting product codes was investigated. The first step in any digital transmission is to establish synchronization between the sending and receiving nodes. This initial synchronization ensures that the receiver samples the information bits at the correct interval. Unfortunately synchronization is not guaranteed to last for the entire duration of data transmission. Though synchronization errors rarely occur, it has disastrous effects at the receiving end of transmission. These synchronization errors are modelled as either insertions or deletions in the transmitted data. In the best case scenario, these errors are restricted to single bit errors. In the worst case scenario, these errors lead to bursts of bits being incorrect. If these synchronization errors are not detected and corrected, it can cause a shift in the transmitted sequence which in turn leads to loss of synchronization. When a signal is subjected to synchronization errors it is difficult accurately recover the original data signal. In addition to the loss of synchronization, the information transmitted over the channel is also subjected to noise. This noise in the channel causes inversion errors within the signal. The objective of this dissertation is to investigate if an error correction scheme can be designed that has the ability to detect and correct adjacent bursts of deletions and random inversion errors. This error correction scheme needed to make use of a product code matrix structure. This product matrix needed to incorporate both an error correction and synchronization technique. The chosen error correcting techniques were Hamming and Reed-Solomon codes. The chosen synchronization techniques for this project were the marker technique or an adaptation of the Hamming code technique. In order to find an effective model, combinations of these models were simulated and compared. From the research obtained and analyzed in this document it was found that, depending on the desired performance, complexity and code rate, an error correction scheme can be used in the efficient correction of bursts of adjacent deletions by adapting product codes.

Page generated in 0.054 seconds