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‣ Processamento de imagens na analise dinamica de risers de produção de petroleo com modelo de escala reduzida em ambiente de laboratorio; Image processing in dynamic analysis of risers of petroleum production with reduced-scale model in a laboratory environment

Luiz Ferreira Menezes Junior
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/07/2008 Português
Relevância na Pesquisa
46.991978%
Este trabalho apresenta o desenvolvimento de uma técnica para o registro e processamento dos sinais de movimento de um modelo reduzido de riser de produção de petróleo, com a utilização de câmeras. O processo se baseia na utilização de alvos fixados no modelo do riser e a detecção de sua posição no espaço. A aplicação da técnica proposta é baseada em uma seqüência de imagens capturadas do alvo, que informa a sua localização e padrão de movimento. É construído um software de processamento de imagens para a aplicação em laboratório. Este tem sua robustez verificada através de imagens geradas em software de simulação de ambiente 2D/3D virtual e de uma aplicação prática. A técnica utiliza conceitos de análise de imagens 2D e 3D, morfologia, visão computacional e processamento de sinais; This work develops a technique for recording and processing the signals of movement of a reduced oil producing riser, with the use of optical cameras. It is based on the use of targets attached to the riser model, and the detection of its position in space. The application of the proposed technique is based on the sequence of images captured from the target, which are indicators of its position and pattern of movement. An image processing software is built with the purpose of laboratory usage. The validation of the software with the proposed technique is verified through 2D/3D virtual simulations as well as a practical application. The technique uses 2D/3D image analysis concepts...

‣ Estudo e projeto de um sistema eletronico de processamento de sinais de girometros a fibra optica com modulação dinamica; The study and design of an electronic system for signal processing of fiber optic gyroscopes with a dynamic modulation

Fernando Ferreira de Melo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 10/12/2009 Português
Relevância na Pesquisa
47.09816%
Esta tese apresenta o estudo e o projeto de um processador eletrônico do sinal de um interferômetro de Sagnac a fibra óptica que procura atender especificações para aplicação em navegação inercial. Estudou-se o comportamento de Girômetros a fibra óptica com modulação de fase senoidal através de modelos e simulações de algumas técnicas de processamento do sinal fotodetectado. Procurou-se responder questões como o sinal mínimo detectável para processadores de sinal específicos, como a técnica Lock-in e da técnica Mean Value. A técnica Mean Value foi modificada visando facilitar a implementação eletrônica e melhorar o desempenho em relação à proposta original. Compromissos entre estabilidade e pontos de operação com melhor resolução, na medida da diferença de fase de Sagnac, foram estabelecidos para o processador projetado. Este processador foi aplicado a um giroscópio óptico projetado por pesquisadores do IEAv/CTA, em São José dos Campos/SP; This thesis presents the study and design of an electronic signal processor for an optical-fiber Sagnac interferometer aimed at inertial navigation applications. The fiberoptic gyroscope behavior under sinusoidal phase modulations was studied through models and simulation of some signal processing techniques. It was attempted to answer questions like lowest detectable signal for some particular processors...

‣ Um estudo sobre a robustez de técnicas de processamento de sinais em sistemas MIMO; A study regarding robustness of signal processing techniques in MIMO systems

Glauco Cesar Crystal Pereira Simões
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/06/2011 Português
Relevância na Pesquisa
46.88849%
Sistemas de comunicação sem fio com múltiplas antenas atingem altas taxas de transmissão de dados e boa robustez ao desvanecimento do canal de comunicação quando os sinais que trafegam pelo sistema são processados conjuntamente em sua transmissão e/ou em sua recepção. Em geral, as técnicas de detecção de sinais assumem o conhecimento perfeito do canal de comunicações, tanto no transmissor, quanto no receptor do sistema, uma hipótese que nem sempre é válida. Neste sentido, é importante analisar o desempenho do sistema frente a erros de estimação do canal de comunicações. Neste trabalho, esta análise é feita através da comparação do cálculo da probabilidade de erro de símbolos com as taxas de erro de símbolos obtidas através de simulação computacional para o detector zero-forcing, assumindo a utilização dos critérios de detecção linear e através da aplicação da técnica de cancelamento sucessivo de interferências; Multiple antenna wireless communication systems achieve high data transmission rates and good robustness to channel fading when signals traveling through the system are jointly processed in their transmitters and/ or receivers. In general, signal detection techniques assume perfect knowledge of the channel state information...

‣ A glycine-rich region in NF-kappaB p105 functions as a processing signal for the generation of the p50 subunit.

Lin, L; Ghosh, S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1996 Português
Relevância na Pesquisa
47.109204%
Transcription factor NF-kappaB is generally considered to be a heterodimer with two subunits, p50 and p65. The p50 subunit has been suggested to be generated from its precursor, p105, via the ubiquitin-proteasome pathway. During processing, the C-terminal portion of p105 is rapidly degraded whereas the N-terminal portion (p50) is left intact. We report here that a 23-amino-acid, glycine-rich region (GRR) in p105 functions as a processing signal for the generation of p50. A GRR-dependent endoproteolytic cleavage downstream of the GRR releases p50 from p105, and this cleavage does not require any specific downstream sequences. p50 can be generated from chimeric precursor p105N-GRR-IkappaBalpha, while the C-terminal portion (IkappaBalpha) can also be recovered, suggesting that p105 processing includes two steps: a GRR-dependent endoproteolytic cleavage and the subsequent degradation of the C-terminal portion. We have also demonstrated that the GRR can direct a similar processing event when it is inserted into a protein unrelated to the NF-kappaB family and that it is therefore an independent signal for processing.

‣ Structural characterization of a ribonuclease III processing signal.

Schweisguth, D C; Chelladurai, B S; Nicholson, A W; Moore, P B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 25/02/1994 Português
Relevância na Pesquisa
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The structure of a ribonuclease III processing signal from bacteriophage T7 was examined by NMR spectroscopy, optical melting, and chemical and enzymatic modification. A 41 nucleotide variant of the T7 R1.1 processing signal has two Watson-Crick base-paired helices separated by an internal loop, consistent with its predicted secondary structure. The internal loop is neither rigidly structured nor completely exposed to solvent, and seems to be helical. The secondary structure of R1.1 RNA is largely insensitive to the monovalent cation concentration, which suggests that the monovalent cation sensitivity of secondary site cleavage by RNase III is not due to a low salt-induced RNA conformational change. However, spectroscopic data show that Mg2+ affects the conformation of the internal loop, suggesting a divalent cation binding site(s) within this region. The Mg(2+)-dependence of RNase III processing of some substrates may reflect not only a requirement for a divalent cation as a catalytic cofactor, but also a requirement for a local RNA conformation which is divalent cation-stabilized.

‣ Defining the enzyme binding domain of a ribonuclease III processing signal. Ethylation interference and hydroxyl radical footprinting using catalytically inactive RNase III mutants.

Li, H; Nicholson, A W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/03/1996 Português
Relevância na Pesquisa
46.95419%
Ethylation interference and hydroxyl radical footprinting were used to identify substrate ribose-phosphate backbone sites that interact with the Escherichia coli RNA processing enzyme, ribonuclease III. Two RNase III mutants were employed, which bind substrate in vitro similarly as wild-type enzyme, but lack detectable phosphodiesterase activity. Specifically, altering glutamic acid at position 117 to lysine or alanine uncouples substrate binding from cleavage. The two substrates examined are based on the bacteriophage T7 R1.1 RNase III processing signal. One substrate, R1.1 RNA, undergoes accurate single cleavage at the canonical site, while a close variant, R1.1[WC-L] RNA, undergoes coordinate double cleavage. The interference and footprinting patterns for each substrate (i) overlap, (ii) exhibit symmetry and (iii) extend approximately one helical turn in each direction from the RNase III cleavage sites. Divalent metal ions (Mg2+, Ca2+) significantly enhance substrate binding, and confer stronger protection from hydroxyl radicals, but do not significantly affect the interference pattern. The footprinting and interference patterns indicate that (i) RNase III contacts the sugar-phosphate backbone; (ii) the RNase III-substrate interaction spans two turns of the A-form helix; and (iii) divalent metal ion does not play an essential role in binding specificity. These results rationalize the conserved two-turn helix motif seen in most RNase III processing signals...

‣ Unitary Equivalence: A New Twist on Signal Processing

Baraniuk, Richard G.; Jones, Douglas L.; Baraniuk, Richard G.; Jones, Douglas L.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.2544%
Journal Paper; Unitary similarity transformations furnish a powerful vehicle for generating infinite generic classes of signal analysis and processing tools based on concepts different from time, frequency, and scale. Implementation of these new tools involves simply preprocessing the signal by a unitary transformation, performing standard processing techniques on the transformed signal, and then (in some cases) transforming the resulting output. The resulting unitarily equivalent systems can focus on the critical signal characteristics in large classes of signals and, hence, prove useful for representing and processing signals that are not well matched by current techniques. As specific examples of this procedure, we generalize linear time-invariant systems, orthonormal basis and frame decompositions, and joint time-frequency and time-scale distributions. These applications illustrate the utility of the unitary equivalence concept for uniting seemingly disparate approaches proposed in the literature.

‣ Sharing Knowledge and Building Communities in Signal Processing

Baraniuk, Richard G.; Burrus, C. Sidney; Johnson, Don; Jones, Douglas L.; Baraniuk, Richard G.; Burrus, C. Sidney; Johnson, Don; Jones, Douglas L.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.09123%
Journal Paper; The textbook has traditionally been the fundamental tool of university teaching. The text both serves as the repository of facts and information and provides the recommended structure and sequence for teaching and learning the material. Today, textbooks can be in traditional paper form or electronically available over the World Wide Web. However, the material in domains like signal processing changes rapidly as new theory, applications, and hardware continually come on the scene. In some ways, having a textbook as a courseâ s main tool actually impedes course and curriculum development.

‣ Contextual Hidden Markov Models for Wavelet-domain Signal Processing

Crouse, Matthew; Baraniuk, Richard G.; Crouse, Matthew; Baraniuk, Richard G.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
47.19242%
Conference Paper; Wavelet-domain hidden Markov models (HMMs) provide a powerful new approach for statistical modeling and processing of wavelet coefficients. In addition to characterizing the statistics of individual wavelet coefficients, HMMs capture some of the key interactions between wavelet coefficients. However, as HMMs model an increasing number of wavelet coefficient interactions, HMM-based signal processing becomes increasingly complicated. In this paper, we propose a new approach to HMMs based on the notion of context. By modeling wavelet coefficient inter-dependencies via contexts, we retain the approximation capabilities of HMMs, yet substantially reduce their complexity. To illustrate the power of this approach, we develop new algorithms for signal estimation and for efficient synthesis of nonGaussian, long-range-dependent network traffic.

‣ The Signal Processing Information Base

Johnson, Don; Shami, P N; Johnson, Don; Shami, P N
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
47.265503%
Conference Paper; The SPIB (Signal Processing Information Base) project at Rice University is discussed. This information base will provide the signal processing researcher and the applications engineer with data, programs, and papers that can be accessed immediately through Internet. An overview of the initial contents of the information base is presented, and the various ways in which it may be accessed are described

‣ Basics of information processing

Johnson, Don; Johnson, Don
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: documents
Português
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46.95419%
Internal Document; Basic probability theory, statistical signal processing and information theory, and inter-relationships among these disciplines form the foundations of a theory of information processing. Examples are drawn from point-process applications.

‣ Analysis of noise reduction in redundant expansions under distributed processing requirements

Rozell, Chris; Johnson, Don; Rozell, Chris; Johnson, Don
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
46.95419%
Conference paper; We considered signal reconstruction with redundant expansions under distributed processing in noisy environments. Redundant expansions have the ability to reduce noise corrupting the coefficients, but distributed processing schemes will not be able to take full advantage of the redundancy present. We apply frame theory and a generalization called â frames of subspacesâ to find conditions when distributed reconstruction suffers no loss in noise reduction ability, and we bound performance loss in more general cases.

‣ Generalized Joint Signal Representations and Optimum Detection

Sayeed, Akbar M.; Jones, Douglas L.; Sayeed, Akbar M.; Jones, Douglas L.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
46.97265%
Conference Paper; Generalized joint signal representations (JSRs) extend the scope of joint time-frequency representations (TFRs) to a richer class of nonstationary signals, but their use, just as in the case of TFRs, has been primarily limited to qualitative, exploratory data analysis. To exploit their potential more fully, JSR-based statistical signal processing techniques need to be developed that can be successfully applied in real-world problems. In this paper, we present an optimal detection framework based on arbitrary generalized quadratic JSRs, thereby making it applicable in a wide variety of detection scenarios involving nonstationary stochastic signals, noise and interference. For any given class of generalized JSRs, we characterize the corresponding class of detection scenarios for which such JSRs constitute canonical detectors, and derive the corresponding JSR-based detectors. Our formulation also yields a very useful subspace-based interpretation in terms of corresponding linear JSRs that we exploit to design optimal detectors based on only partial signal information.

‣ Random Projections of Signal Manifolds

Wakin, Michael; Baraniuk, Richard G.; Wakin, Michael; Baraniuk, Richard G.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
47.0508%
Conference Paper; Random projections have recently found a surprising niche in signal processing. The key revelation is that the relevant structure in a signal can be preserved when that signal is projected onto a small number of random basis functions. Recent work has exploited this fact under the rubric of Compressed Sensing (CS): signals that are sparse in some basis can be recovered from small numbers of random linear projections. In many cases, however, we may have a more specific low-dimensional model for signals in which the signal class forms a nonlinear manifold in R^N. This paper provides preliminary theoretical and experimental evidence that manifold-based signal structure can be preserved using small numbers of random projections. The key theoretical motivation comes from Whitneyâ s Embedding Theorem, which states that a K-dimensional manifold can be embedded in R^{2K+1}. We examine the potential applications of this fact. In particular, we consider the task of recovering a manifold-modeled signal from a small number of random projections. Thanks to our (more specific) model, the ability to recover the signal can be far superior to existing techniques in CS.

‣ Automatization techniques for processing biomedical signals using machine learning methods

Artés Rodríguez, Antonio
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Relatório Formato: application/pdf
Publicado em 15/04/2008 Português
Relevância na Pesquisa
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The Signal Processing Group (Department of Signal Theory and Communications, University Carlos III, Madrid, Spain) offers the expertise of its members in the automatic processing of biomedical signals. The main advantages in this technology are the decreased cost, the time saved and the increased reliability of the results. Technical cooperation for the research and development with internal and external funding is sought.

‣ Toward a theory of information processing

Sinanovic, Sinan; Johnson, Don; Sinanovic, Sinan; Johnson, Don
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Journal article; Text; Text
Português
Relevância na Pesquisa
47.17811%
Journal Paper; Information processing theory endeavors to quantify how well signals encode information and how well systems, by acting on signals, process information. We use information-theoretic distance measures, the Kullback-Leibler distance in particular, to quantify how well signals represent information. The ratio of distances calculated between two informationally different signals at a system's output and input quantifies the system's information processing properties. Using this approach, we derive the fundamental processing capabilities of simple system architectures that apply universally: the systems and the kinds of signals they process and produce don't affect our general results. Applications in array signal processing and in neural signal analysis illustrate how to apply the theory.; National Science Foundation

‣ Analyzing Dynamics and Stimulus Feature Dependence in the Information Processing of Crayfish Sustaining Fibers

Rozell, Chris; Rozell, Chris
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text; Text
Português
Relevância na Pesquisa
47.04291%
Masters Thesis; The sustaining fiber (SF) stage of the crayfish visual system converts analog stimulus representations to spike train signals. A recent theory quantifies a system's information processing capabilities and relates to statistical signal processing. To analyze SF responses to light stimuli, we extend a wavelet-based algorithm for separating analog input signals and spike output waveforms in composite intracellular recordings. We also present a time-varying RC circuit model to capture nonstationary membrane noise spectral characteristics. In our SF anlysis, information transfer ratios are generally on the order of (10-4). The SF information processing dynamics show transient peaks followed by decay to steady-state values. A simple theoretical spike generator is analyzed analytically and shows general dynamic and steady-state properties similar to SFs. The information transfer ratios increase with spike rate and dynamic properties are due to direct spike generator dependence on input changes.; Texas Instruments; National Science Foundation; National Institute of Mental Health

‣ Ribonuclease III cleavage of a bacteriophage T7 processing signal. Divalent cation specificity, and specific anion effects.

Li, H L; Chelladurai, B S; Zhang, K; Nicholson, A W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 25/04/1993 Português
Relevância na Pesquisa
46.991978%
Escherichia coli ribonuclease III, purified to homogeneity from an overexpressing bacterial strain, exhibits a high catalytic efficiency and thermostable processing activity in vitro. The RNase III-catalyzed cleavage of a 47 nucleotide substrate (R1.1 RNA), based on the bacteriophage T7 R1.1 processing signal, follows substrate saturation kinetics, with a Km of 0.26 microM, and kcat of 7.7 min.-1 (37 degrees C, in buffer containing 250 mM potassium glutamate and 10 mM MgCl2). Mn2+ and Co2+ can support the enzymatic cleavage of the R1.1 RNA canonical site, and both metal ions exhibit concentration dependences similar to that of Mg2+. Mn2+ and Co2+ in addition promote enzymatic cleavage of a secondary site in R1.1 RNA, which is proposed to result from the altered hydrolytic activity of the metalloenzyme (RNase III 'star' activity), exhibiting a broadened cleavage specificity. Neither Ca2+ nor Zn2+ support RNase III processing, and Zn2+ moreover inhibits the Mg(2+)-dependent enzymatic reaction without blocking substrate binding. RNase III does not require monovalent salt for processing activity; however, the in vitro reactivity pattern is influenced by the monovalent salt concentration, as well as type of anion. First, R1.1 RNA secondary site cleavage increases as the salt concentration is lowered...

‣ Optical signal processing and real world applications

Naulleau, Patrick
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
47.013994%
It is common to want to correct signals that have been corrupted by wideband dispersion. If the dispersion is caused by a system whose transfer function has a flat amplitude function and a nonlinear phase function, such as is the case with a ltig periodic antenna, the signal can be corrected via a matched filter. In this paper various optical implementations of the matched filter, including one and two dimensional systems, are investigated. The 2D Fourier Filter, along with several simplifications, demonstrating its power, are simulated. The optical implementations of these systems are also discussed. The problem of phase detection of a spatial signal, which arises when dealing with Fourier transforms, is briefly examined and a system capable of measuring said phase is experimentally implemented. Finally a dual Acousto-Optic matched filter is implemented concentrating on the practical aspects the setup. An exhaustive description of the implementation process is presented including experimental results obtained from each step.

‣ Color image processing: Basics and special issue overview

Trussell, H. Joel; Saber, Eli; Vrhel, Michael
Fonte: IEEE Signal processing magazine Publicador: IEEE Signal processing magazine
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.071416%
Humans have always seen the world in color but only recently have we been able to generate vast quantities of color images with such ease. In the last three decades, we have seen a rapid and enormous transition from grayscale images to color ones. Today, we are exposed to color images on a daily basis in print, photographs, television, computer displays, and cinema movies, where color now plays a vital role in the advertising and dissemination of information throughout the world. Color monitors, printers, and copiers now dominate the office and home environments, with color becoming increasingly cheaper and easier to generate and reproduce. Color demands have soared in the marketplace and are projected to do so for years to come. With this rapid progression, color and multispectral properties of images are becoming increasingly crucial to the field of image processing, often extending and/or replacing previously known grayscale techniques. We have seen the birth of color algorithms that range from direct extensions of grayscale ones, where images are treated as three monochrome separations, to more sophisticated approaches that exploit the correlations among the color bands, yielding more accurate results. Hence, it is becoming increasingly necessary for the signal processing community to understand the fundamental differences between color and grayscale imaging. There are more than a few extensions of concepts and perceptions that must be understood in order to produce successful research and products in the color world.; Personal use of this material is permitted. However...