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Tesi sul tema "Signal processing Mathematical models"
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1
Fabrizio, Giuseppe Aureliano. "Space-time characterisation and adaptive processing of ionospherically-propagated HF signals /". Title page, table of contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phf129.pdf.
Testo completo
2
Cai, Qin. "Detecting Chaotic Signals with Nonlinear Models". PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/4564.
Testo completoAbstract (sommario):
In this thesis we apply chaotic dynamic data analysis to the area of discrete time signal processing. A newly developed Hidden Filter Hidden Markov Model is introduced in detection of chaotic signals. Numerical experiments have verified that this novel nonlinear model outperforms linear AR model in detecting chaotic signals buried by noise having similar power spectra. A simple Histogram Model is proposed which can also be used to do detection on the data sets with chaotic behavior. Receiver Operating Characteristics for a variety of noise levels and model classes are reported.
3
Webb, M. R. "Millimetre wave quasi-optical signal processing systems". Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/2827.
Testo completoAbstract (sommario):
The development of spatial signal processing techniques at millimetre wavelengths represents an area of science and technology that is new. At optical wavelengths, spatial signal processing techniques are well developed and are being applied to a variety of situations. In particular they are being used in pattern recognition systems with a great deal of success. At millimetre wavelengths, the kind of technology used for signal transport and processing is typically either waveguide based or quasi-optically based, or some hybrid of the two. It is the use of quasi-optical methods that opens up the possibility of applying some of the spatial signal processing techiques that up to the present time have almost exclusively been used at optical wavelengths. A generic device that opens up this dimension of spatial signal processing to millimetre wave quasi-optical systems is at the heart of the work described within this thesis. The device could be suitably called a millimetre wave quasi-optical spatial light modulator (8LM), and is identical in operation to the spatial light modulators used in many optical signal processing systems. Within this thesis both a theoretical and an experimental analysis of a specific millimetre wave quasi-optical spatial light modulator is undertaken. This thesis thus represents an attempt to open up this new area of research and development, and to establish for it, a helpful theoretical and experimental foundation. It is an area that involves a heterogeneous mix of various technologies, and it is an area that is full of potential. The development of the experimental method for measuring the beam patterns produced by millimetre wave quasi-optical spatial light modulators involved the separate development of two other components. Firstly, a sensitive, low-cost millimetre wave pyroelectric detector has been developed and characterised. And secondly, a high performance quasi-optical Faraday rotator (a polarisation rotator) has been developed and characterised. The polarisation state of a quasi-optical beam is the parameter most often exploited for signal processing applications in millimetre wave quasi-optical systems, and thus a high performance polarisation rotator has readily found many opportunities for use.
4
Zhang, Zhiguo, e 張治國. "On bandwidth and scale selection in processing of time-varying signalswith applications". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39707465.
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5
Selén, Yngve. "Model selection /". Uppsala : Univ. : Dept. of Information Technology, Univ, 2004. http://www.it.uu.se/research/reports/lic/2004-003/.
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6
Stoffell, Kevin M. "Implementation of a Quadrature Mirror Filter Bank on an SRC reconfigurable computer for real-time signal processing". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FStoffell.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2006.Thesis Advisor(s): Douglas J. Fouts. "September 2006." Includes bibliographical references (p. 111-112). Also available in print.
7
洪觀宇 e Roy Hung. "Time domain analysis and synthesis of cello tones based on perceptual quality and playing gestures". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31215348.
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Li, Xiao, e 李驍. "Channel estimation and timing synchronization in cooperative communication systems". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42841835.
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9
Sadeghi, Parastoo School of Electrical Engineering And Telecommunications UNSW. "Modelling, information capacity, and estimation of time-varying channels in mobile communication systems". Awarded by:University of New South Wales. School of Electrical Engineering And Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/32310.
Testo completoAbstract (sommario):
In the first part of this thesis, the information capacity of time-varying fading channels is analysed using finite-state Markov channel (FSMC) models. Both fading channel amplitude and fading channel phase are modelled as finite-state Markov processes. The effect of the number of fading channel gain partitions on the capacity is studied (from 2 to 128 partitions). It is observed that the FSMC capacity is saturated when the number of fading channel gain partitions is larger than 4 to 8 times the number of channel input levels. The rapid FSMC capacity saturation with a small number of fading channel gain partitions can be used for the design of computationally simple receivers, with a negligible loss in the capacity. Furthermore, the effect of fading channel memory order on the capacity is studied (from first- to fourth-order). It is observed that low-order FSMC models can provide higher capacity estimates for fading channels than high-order FSMC models, especially when channel states are poorly observable in the presence of channel noise. To explain the effect of memory order on the FSMC capacity, the capacities of high-order and low-order FSMC models are analytically compared. It is shown that the capacity difference is caused by two factors: 1) the channel entropy difference, and 2) the channel observability difference between the high-order and low-order FSMC models. Due to the existence of the second factor, the capacity of high-order FSMC models can be lower than the capacity of low-order FSMC models. Two sufficient conditions are proven to predict when the low-order FSMC capacity is higher or lower than the high-order FSMC capacity. In the second part of this thesis, a new implicit (blind) channel estimation method in time- varying fading channels is proposed. The information source emits bits ???0??? and ???1??? with unequal probabilities. The unbalanced source distribution is used as a priori known signal structure at the receiver for channel estimation. Compared to pilot-symbol-assisted channel estimation, the proposed channel estimation technique can achieve a superior receiver bit error rate performance, especially at low signal to noise ratio conditions.
10
Yang, Yang. "2D signal processing: efficient models for spectral compressive sensing & single image reflection suppression". Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6667.
Testo completoAbstract (sommario):
Two efficient models in two-dimensional signal processing are proposed in the thesis.
The first model deals with large scale spectral compressive sensing in continuous domain, which aims to recover a 2D spectrally sparse signal from partially observed time samples. The signal is assumed to be a superposition of s complex sinusoids. We propose a semidefinite program for the 2D signal recovery problem. Our model is able to handle large scale 2D signals of size 500*500, whereas traditional approaches only handle signals of size around 20*20.
The second model deals with the problem of single image reflection suppression. Removing the undesired reflection from images taken through glass is of great importance in computer vision. It serves as a means to enhance the image quality for aesthetic purposes as well as to preprocess images in machine learning and pattern recognition applications. We propose a convex model to suppress the reflection from a single input image. Our model implies a partial differential equation with gradient thresholding, which is solved efficiently using Discrete Cosine Transform. Extensive experiments on synthetic and real-world images demonstrate that our approach achieves desirable reflection suppression results and dramatically reduces the execution time compared to the state of the art.
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Britton, Matthew Scott. "Stochastic task scheduling in time-critical information delivery systems". Title page, contents and abstract only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phb8629.pdf.
Testo completoAbstract (sommario):
"January 2003" Includes bibliographical references (leaves 120-129) Presents performance analyses of dynamic, stochastic task scheduling policies for a real- time-communications system where tasks lose value as they are delayed in the system.
12
Shah, Nauman. "Statistical dynamical models of multivariate financial time series". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:428015e6-8a52-404e-9934-0545c80da4e1.
Testo completoAbstract (sommario):
The last few years have witnessed an exponential increase in the availability and use of financial market data, which is sampled at increasingly high frequencies. Extracting useful information about the dependency structure of a system from these multivariate data streams has numerous practical applications and can aid in improving our understanding of the driving forces in the global financial markets. These large and noisy data sets are highly non-Gaussian in nature and require the use of efficient and accurate interaction measurement approaches for their analysis in a real-time environment. However, most frequently used measures of interaction have certain limitations to their practical use, such as the assumption of normality or computational complexity. This thesis has two major aims; firstly, to address this lack of availability of suitable methods by presenting a set of approaches to dynamically measure symmetric and asymmetric interactions, i.e. causality, in multivariate non-Gaussian signals in a computationally efficient (online) framework, and secondly, to make use of these approaches to analyse multivariate financial time series in order to extract interesting and practically useful information from financial data. Most of our proposed approaches are primarily based on independent component analysis, a blind source separation method which makes use of higher-order statistics to capture information about the mixing process which gives rise to a set of observed signals. Knowledge about this information allows us to investigate the information coupling dynamics, as well as to study the asymmetric flow of information, in multivariate non-Gaussian data streams. We extend our multivariate interaction models, using a variety of statistical techniques, to study the scale-dependent nature of interactions and to analyse dependencies in high-dimensional systems using complex coupling networks. We carry out a detailed theoretical, analytical and empirical comparison of our proposed approaches with some other frequently used measures of interaction, and demonstrate their comparative utility, efficiency and accuracy using a set of practical financial case studies, focusing primarily on the foreign exchange spot market.
13
Zhang, Mingyang 1981. "Macromodeling and simulation of linear components characterized by measured parameters". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112589.
Testo completoAbstract (sommario):
Recently, microelectronics designs have reached extremely high operating frequencies as well as very small die and package sizes. This has made signal integrity an important bottleneck in the design process, and resulted in the inclusion of signal integrity simulation in the computer aided design flow. However, such simulations are often difficult because in many cases it is impossible to derive analytical models for certain passive elements, and the only available data are frequency-domain measurements or full-wave simulations. Furthermore, at such high frequencies these components are distributed in nature and require a large number of poles to be properly characterized. Simple lumped equivalent circuits are therefore difficult to obtain, and more systematic approaches are required. In this thesis we study the Vector Fitting techniques for obtaining such equivalent model and propose a more streamlined approach for preserving passivity while maintaining accuracy.
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Sousa, Éricles Rodrigues. "Arquitetura computacional híbrida baseada em DSP e FPGA para processamento digital de sinais". [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259485.
Testo completoAbstract (sommario):
Orientador: Luís Geraldo Pedroso MeloniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Atualmente, aplicações multimídias exigem grande esforço computacional para manipular dados com elevadas taxas de precisão. Visando otimizar a capacidade de processamento sem elevar demasiadamente o custo do desenvolvimento em sistemas embarcados, este trabalho descreve a proposta de uma arquitetura computacional hibrida, para processamento digital de sinais, baseado-se no uso cooperativo entre DSP (Digital Signal Processor) e FPGA (Field Programmable Gate Array). Neste estudo e realizada uma abordagem sobre o uso de um coprocessador para a acelerar rotinas que demandam grande esforço computacional em um DSP. Também e proposto um modelo matemático capaz de mensurar a eficiência do particionamento de códigos processados de forma descentralizada. Para validação da proposta, foi construído um cenários de testes para a estimação de vetores movimento, um dos principais agentes envolvidos no processo de codificação de vídeo em alta definição. A partir do cenário elaborado foi possível constatar a eficiência da arquitetura proposta. Sendo que, considerando um código de referencia otimizado e baseado na descrição feita em [30], obteve-se mais de 97% de eficiência computacional. Assim, este estudo permite concluir que o uso cooperativo entre DSP e FPGA se mostra muito vantajoso devido a possibilidade de unir em um único sistema as vantagens fornecidas por ambos dispositivos, caracterizando um ambiente de total sinergia e de elevada capacidade de computacional
Abstract: Nowadays, multimedia applications require high computational effort to manipulate data with high precision. In order to optimize the processing power without significantly increasing the cost of development in embedded systems, this work describes the proposal for a hybrid computing architecture applied to digital signal processing, based on the cooperative work between DSP (Digital Signal Processor) and FPGA (Field Programmable Gate Array). An approach about the use of coprocessor able to accelerate a process which requires great computational effort of a DSP is provided by this study. It is also describes a mathematical model able to measure the efficiency of a partitioning code processed in a distributed system. To validate our proposal we developed a tested for calculate the motion estimation vector, which is one of key elements involved on high definition video coding. From the elaborated tested, we could found a high efficiency provided by the architecture proposed. Therefore, considering a optimized reference code based on [30], was possible achieve a computing efficiency around 97%. This study show that cooperative work between DSP and FPGA that provides a very advantageous scenario applied to embedded systems, due to joining the features of both devices, building then, a synergy environment of high computing performance
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
15
Asif, Muhammad Salman. "Primal dual pursuit a homotopy based algorithm for the Dantzig selector /". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24693.
Testo completoAbstract (sommario):
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Romberg, Justin; Committee Member: McClellan, James; Committee Member: Mersereau, Russell
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Barreira, Ramiro Roque Antunes. "Modelo mel-cepstral generalizado para envoltória espectral de fala". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259047.
Testo completoAbstract (sommario):
Orientadores: Fábio Violaro, Edmilson da Silva MoraisDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: A análise Mel-Cepstral Generalizada (MGC) corresponde a uma abordagem para estimação de envoltória espectral de fala que unifica as análises LPC, Mel-LPC, Cepstral e Mel-Cepstral. A forma funcional do modelo MGC varia continuamente com dois parâmetros reais ? e ?, possibilitando que o modelo assuma diferentes características. A flexibilidade oferecida pelo modelo MGC aliada à sua estabilidade e bom desempenho sob manipulação de parâmetros tem feito com que os parâmetros MGC sejam empregados com sucesso em codificação de fala e síntese de fala via HMM (Hidden Markov Models). O presente trabalho foca os aspectos matemáticos da análise MGC, abordando e demonstrando, em extensão, a formulação em seus vieses analítico e computacional para a solução do modelo. As propriedades e formulações básicas da análise MGC são tratadas na perspectiva do espectro mel-logarítmico generalizado. Propõe-se um método para a computação dos coeficientes MGC e Mel-Cepstrais que não envolve o uso de fórmulas recursivas de transformação em freqüência. As análises e experimentos relacionados ao método encontram-se em estágio inicial e devem ser completados no sentido de se identificar a relação ganho computacional × qualidade da representação.
Abstract: Mel-Generalized Cepstral analysis (MGC) is an approach for speech spectral envelope estimation that unifies LPC, Mel-LPC, Cepstral and Mel-Cepstral Analysis. The functional form of the MGC model varies continuously with the real parameters ? e ?, enabling the model to acquire different characteristics. The flexibility of MGC model associated with its stability and good performance under parameter manipulation have made MGC parameters to be successfully employed in speech codification and HMM speech synthesis. The present study focuses on mathematical aspects of MGC analysis, treating and proving, in a fairly extended way, analytical and computational formulation for model solution. MGC analysis properties and basic formulation are treated in melgeneralized logarithmic spectrum perspective. A method for the computation of MGC and Mel-Cepstral coefficients that do not require frequency transformation recursion formulas is proposed. Experiments and analysis concerning the method are in their initial stage and needs to be completed in the sense to identify computational × representation performances.
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
17
Silvestre, Bezerra Manoel Ivanildo 1961. "Proposta de um método sub-ótimo para estimação espectral do modelo ARMA". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261228.
Testo completoAbstract (sommario):
Orientador: Yuzo IanoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Neste trabalho é proposto um novo método de estimação separada (sub-ótimo) para o processo (modelo) espectral ARMA. Os métodos sub-ótimos utilizam-se das equações de Yule-Walker e do método de mínimos quadrados para as estimativas AR, e geralmente do método de Durbin para as estimativas MA. Dado que os parâmetros AR e MA já foram estimados, no método proposto é feita uma nova filtragem AR do sinal de interesse utilizando-se as estimativas da parte MA. A partir deste novo sinal estimado, determinam-se as novas estimativas das partes AR e MA do processo ARMA, e em seguida obtém-se a estimativa da densidade espectral de potência. Os resultados dependem muito do espectro de interesse, e da parametrização que foi utilizada, mas de um modo geral os resultados fornecidos foram muito bons. Um estudo descrevendo os principais métodos de estimação espectral paramétrica dos processos ARMA também é realizado neste trabalho. Esses métodos são comparados medindo a precisão através do erro relativo e do coeficiente de variação médio das estimativas dos parâmetros
Abstract: This work proposes a new method of estimating separate (sub-optimal) for the spectrum ARMA process (model). The sub-optimal methods use the Yule-Walker equations and the method of least squares estimates for the AR, and usually the method of Durbin estimates for MA. Since AR and MA parameters have been estimated, in the method it is made a new AR filtering of the signal of interest using the estimates of the MA. From this new estimated signal, the new AR and MA estimates of parts from the ARMA process are obtained, and then the power spectral density is estimated. The results depend so much on the spectrum of interest and the parameterization used in the process, but generally the final results were very good. A study describing the main methods of parametric spectral estimation of ARMA processes is also performed in this work. These methods are compared by measuring their accuracy through the relative error and the average coefficient of variation of the parameter estimates
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica
18
Iskander, D. R. "The Generalised Bessel function K distribution and its application to the detection of signals in the presence of non-Gaussian interference". Thesis, Queensland University of Technology, 1997.
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19
Delgado, Eric Magalhães. "Um estudo sobre algoritmos de interpolação de sequencias numericas". [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259648.
Testo completoAbstract (sommario):
Orientador: Max Henrique Machado CostaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Esta dissertação apresenta um estudo sobre algoritmos de interpolação e dizimação de sequências numéricas, cujos filtros são derivados do filtro de reconstrução ideal. É proposto um algoritmo adaptativo de interpolação cúbica e avaliado os ganhos deste algoritmo quando comparado aos algoritmos clássicos. A idéia é explorar o compromisso entre qualidade e complexidade dos filtros de interpolação. A adaptação do filtro, obtida através de estimativas espaciais e espectrais da sequência a ser interpolada, é útil já que proporciona um uso eficiente de filtros complexos em regiões criticas como, por exemplo, regiões de borda de uma imagem. Simulações em imagens típicas mostram um ganho quantitativo significativo do algoritmo adaptativo quando comparado aos algoritmos clássicos. Além disso, é analisado o algoritmo de interpolação quando existe informação do processo de aquisição da sequência a ser interpolada.
Abstract: This dissertation presents a study on interpolation and decimation algorithms of numerical sequences, whose filters are derived from the ideal reconstruction filter. An adaptive algorithm of cubic interpolation is proposed and the gains of this algorithm is analized by comparing with the classic algorithms. The idea is to explore the trade-off between quality and complexity of the interpolation filters. The adaptation of the filter, obtained from spacial and spectral estimates of the sequence to be interpolated, is useful because it provides an efficient use of complex filter in critical regions as, for example, regions of edge of an image. Simulations in typical images show a significant quantitative gain of the adaptive algorithm when compared to classical algorithms. Furthermore, an interpolation algorithm is analyzed based on the knowledge of the acquisition process of the sequence to be interpolated.
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
20
Rodrigues, Romulo Luis de Paiva. "Caracterização experimental do escoamento bifásico de gás-líquido descendente em golfadas em tubulações levemente inclinadas". Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1307.
Testo completoAbstract (sommario):
CAPES; PETROBRASO escoamento de gás-líquido descendente, no padrão golfadas é frequentemente encontrado em linhas de produção de petróleo provocado pela topografia do terreno. Assim, é necessário entender a dinâmica deste tipo de escoamento para o projeto de linhas de produção de óleo e gás, assim como para o dimensionamento de separadores e equipamentos. Neste cenário, no presente trabalho é caraterizado experimentalmente o escoamento bifásico de líquido-gás no padrão intermitente na direção descendente, em tubulações com inclinações de 0°, −4°, −7°, −10° e −13°. O estudo foi realizado utilizando o circuito experimental instalado no NUEM/UTFPR. Os experimentos foram conduzidos para diferentes condições de vazão de líquido e gás que garantam o padrão intermitente em golfadas, e para a monitoração das estruturas (fases) do escoamento foi utilizado um par de sensores de malha de eletrodos. A partir dos sinais temporais da fração de vazio adquiridos, foram extraídas as distribuições estatísticas dos parâmetros característicos do escoamento em golfadas, sendo estes: a velocidade de translação da bolha alongada, a frequência de passagem da célula unitária, o comprimento do pistão de líquido, o comprimento da bolha alongada e a fração de vazio na região da bolha alongada. Em posse dos dados experimentais processados, estes foram analisados com a finalidade de identificar a relação entre os parâmetros do escoamento em golfadas, tanto para suas distribuições estatísticas como para seu valor médio, com as vazões e propriedade dos fluidos. Foram elaboradas correlações, com intervalo de confiança de 95%, para calcular a frequência, velocidade da bolha alongada, comprimentos do pistão e da bolha, fração do líquido e de vazio; que certamente servirão de referência para o desenvolvimento de modelos matemáticos e desenvolvimento de projetos de engenharia.
Downward slug flow in ducts of circular cross section is a frequently observed flow regime in oil and gas transportation lines. The onset of this kind of flow is due to instabilities generated by irregular pipe topography. Therefore, to understand the hydrodynamics of the slug flow is paramount in the design of crude oil production lines as well as in the project of equipment involved in oil and gas operations. The goal of this work is to experimentally analyze and characterize the two-phase gas-liquid intermittent downward flow in ducts with inclination angles of 0°, −4°, −7°, −10° and −13°. The analysis was performed at different gas-liquid volumetric flow rates for which the slug flow regime was observed. An existing experimental rig in the NUEM/UTFPR labs was used to collect data. A pair of wire-mesh sensors to evaluate the flow structure, thus obtaining void fraction temporal series was employed. From those series, statistical distributions for the characteristic parameters of such slug flows – namely the elongated bubble translational velocity, the unit cell frequency, the liquid slug and the elongated bubble lengths and the void fraction in the elongated bubble region – were obtained. The processed signals were analyzed so as to identify the relationship between the slug flow parameters, their statistical distributions and averaged values alike as functions of the flow rates and fluid properties. Correlations for slug frequency, elongated bubble velocity, liquid slug and bubble lengths as well as empirical expressions for the void and liquid fractions were developed, all within a confidence interval of 95%. It is expected that such correlations may contribute to the betterment of future engineering endeavours, and used in the development of similar mathematical models.
21
Seacrest, Tyler. "Mathematical Models of Image Processing". Scholarship @ Claremont, 2006. https://scholarship.claremont.edu/hmc_theses/188.
Testo completoAbstract (sommario):
The purpose of this thesis is to develop various advanced linear algebra techniques that apply to image processing. With the increasing use of computers and digital photography, being able to manipulate digital images efficiently and with greater freedom is extremely important. By applying the tools of linear algebra, we hope to improve the ability to process such images. We are especially interested in developing techniques that allow computers to manipulate images with the least amount of human guidance. In Chapter 2 and Chapter 3, we develop the basic definitions and linear algebra concepts that lay the foundation for later chapters. Then, in Chapter 4, we demonstrate techniques that allow a computer to rotate an image to the correct orientation automatically, and similarly, for the computer to correct a certain class of color distortion automatically. In both cases, we use certain properties of the eigenvalues and eigenvectors of covariance matrices. We then model color clashing and color variation in Chapter 5 using a powerful tool from linear algebra known as the Perron-Frobenius theorem. Finally, we explore ways to determine whether an image is a blur of another image using invariant functions. The inspiration behind these functions are recent applications of Lie Groups and Lie algebra to image processing.
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Reis, Diego Dias dos. "Desenvolvimento de sensores planares em tecnologia de circuitos impressos para detecção de umidade em madeiras e presença de água em dutos hidráulicos". Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1172.
Testo completoAbstract (sommario):
CNPq; CapesNeste trabalho é utilizado a tecnologia convencional de fabricação de circuitos impressos, que possuem vantagens de ser de baixo custo, facilidade de produção, tecnologia conhecida e divulgada, para se desenvolver dois tipos básicos de sensores planares. O primeiro um capacitivo que opera pela detecção da variação da permissividade do meio e um segundo do tipo passivo, wireless e ressonante (PWR) que varia a frequência ressonante em função da permissividade ou permeabilidade do meio. Além disso, são apresentadas análises matemáticas, simulações e medições. Com os sensores foram realizados testes para a detecção da presença de água em dutos hidráulicos e umidade em amostras de madeiras, cujos resultados indicam que os sensores atendem ao propósito de medição e podem ser utilizados para os seus fins específicos.
In this work it was used the conventional manufacturing technology for printed circuits, which presents advantages of being low cost, known technology, for developing two basic types of planar sensors. The first one operates by capacitive measurements of variation of permittivity of medium and a second type of passive, wireless, resonant (PWR) which changes the resonant frequency as a function of permittivity or permeability. Furthermore, two types of sensors are described from the point of view of mathematical analysis, simulations, and measurements. Tests were performed to detect the presence of water in hydraulic ducts and moisture of wood samples. The results indicate that evaluated sensors serve the purpose and can be used for their specific applications.
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Xu, Luzhou. "Growth curve models in signal processing applications". [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015020.
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MOREIRA, GREGORI de A. "Métodos para obtenção da altura da camada limite planetária a partir de dados de Lidar". reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10564.
Testo completoAbstract (sommario):
Made available in DSpace on 2014-10-09T12:42:00Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:04:50Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Sedaaghi, Mohammad Hossein. "Morphological filtering in signal/image processing". Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367104.
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Alves, Rafael Fabricio. "Estudo experimental do escoamento bifásico líquido gás em golfadas com leve mudança de direção". Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1708.
Testo completoAbstract (sommario):
CAPESEscoamentos bifásicos gás-líquido são muito comuns em aplicações industriais, especialmente nas indústrias de petróleo e gás, química e nuclear. Conforme variam as condições operacionais tais como vazões das fases, dimensão das tubulações e propriedades físicas dos fluidos, ocorrem diferentes configurações geométricas conhecidas como padrões de escoamento. No caso da produção de petróleo, o padrão encontrado com maior frequência é o de golfadas, onde se alternam regiões contínuas de líquido (pistões) e regiões de preponderância gasosa (bolhas alongadas). Em operações de produção de petróleo em águas profundas é comum encontrar cenários onde a tubulação ajusta-se ao relevo do leito marinho, apresentando leves mudanças de direção. Nesse contexto, no presente trabalho é desenvolvido um estudo experimental do escoamento bifásico líquido-gás no padrão golfadas em um duto com leve mudança de direção, composto por um trecho horizontal seguido por um trecho inclinado descendente. São produzidos escoamentos em condições controladas, dos quais são extraídos alguns parâmetros característicos. Os fluidos usados são água e ar e os experimentos são realizados no circuito de testes presente no NUEM (Núcleo de Escoamentos Multifásicos da UTFPR). A extração dos parâmetros é feita através de sensores resistivos, instalados em quatro seções da tubulação. Adicionalmente, duas câmeras de alta taxa de aquisição de imagens são utilizadas. Com os resultados obtidos, avalia-se a influência de uma leve mudança de direção nos parâmetros característicos e na transição do escoamento em golfadas para estratificado na região descendente.
Gas-liquid two-phase flow is very common in industrial applications, especially in the oil and gas, chemical, and nuclear industries. As operating conditions change such as the flow rates of the phases, the pipe diameter and physical properties of the fluids, different configurations called flow patterns take place. In the case of oil production, the most frequent pattern found is slug flow, in which continuous liquid plugs (liquid slugs) and gas-dominated regions (elongated bubbles) alternate. Offshore scenarios where the pipe lies onto the seabed with slight changes of direction are extremely common. With those scenarios and issues in mind, this work presents an experimental study of two-phase gas-liquid slug flows in a duct with a slight change of direction, represented by a horizontal section followed by a downward sloping pipe stretch. The experiments were carried out at NUEM (Núcleo de Escoamentos Multifásicos UTFPR). The flow initiated and developed under controlled conditions and their characteristic parameters were measured with resistive sensors installed at four pipe sections. Two high-speed cameras were also used. With the measured results, it was evaluated the influence of a slight direction change on the slug flow structures and on the transition between slug flow and stratified flow in the downward section.
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Ji, Tianyao. "Advanced mathematical morphology and its application to signal processing". Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511063.
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Klingspor, Måns. "Hilbert Transform : Mathematical Theory and Applications to Signal processing". Thesis, Linköpings universitet, Matematik och tillämpad matematik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122736.
Testo completoAbstract (sommario):
The Hilbert transform is a widely used transform in signal processing. In this thesis we explore its use for three different applications: electrocardiography, the Hilbert-Huang transform and modulation. For electrocardiography, we examine how and why the Hilbert transform can be used for QRS complex detection. Also, what are the advantages and limitations of this method? The Hilbert-Huang transform is a very popular method for spectral analysis for nonlinear and/or nonstationary processes. We examine its connection with the Hilbert transform and show limitations of the method. Lastly, the connection between the Hilbert transform and single-sideband modulation is investigated.
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Lynch, Michael Richard. "Adaptive techniques in signal processing and connectionist models". Thesis, University of Cambridge, 1990. https://www.repository.cam.ac.uk/handle/1810/244884.
Testo completoAbstract (sommario):
This thesis covers the development of a series of new methods and the application of adaptive filter theory which are combined to produce a generalised adaptive filter system which may be used to perform such tasks as pattern recognition. Firstly, the relevant background adaptive filter theory is discussed in Chapter 1 and methods and results which are important to the rest of the thesis are derived or referenced. Chapter 2 of this thesis covers the development of a new adaptive algorithm which is designed to give faster convergence than the LMS algorithm but unlike the Recursive Least Squares family of algorithms it does not require storage of a matrix with n2 elements, where n is the number of filter taps. In Chapter 3 a new extension of the LMS adaptive notch filter is derived and applied which gives an adaptive notch filter the ability to lock and track signals of varying pitch without sacrificing notch depth. This application of the LMS filter is of interest as it demonstrates a time varying filter solution to a stationary problem. The LMS filter is next extended to the multidimensional case which allows the application of LMS filters to image processing. The multidimensional filter is then applied to the problem of image registration and this new application of the LMS filter is shown to have significant advantages over current image registration methods. A consideration of the multidimensional LMS filter as a template matcher and pattern recogniser is given. In Chapter 5 a brief review of statistical pattern recognition is given, and in Chapter 6 a review of relevant connectionist models. In Chapter 7 the generalised adaptive filter is derived. This is an adaptive filter with the ability to model non-linear input-output relationships. The Volterra functional analysis of non-linear systems is given and this is combined with adaptive filter methods to give a generalised non-linear adaptive digital filter. This filter is then considered as a linear adaptive filter operating in a non-linearly extended vector space. This new filter is shown to have desirable properties as a pattern recognition system. The performance and properties of the new filter is compared with current connectionist models and results demonstrated in Chapter 8. In Chapter 9 further mathematical analysis of the networks leads to suggested methods to greatly reduce network complexity for a given problem by choosing suitable pattern classification indices and allowing it to define its own internal structure. In Chapter 10 robustness of the network to imperfections in its implementation is considered. Chapter 11 finishes the thesis with some conclusions and suggestions for future work.
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Rao, Tandhoni. "Noncausal methods and models for image". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/13344.
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Krishna, Ranaji. "Mathematical optimisation and signal processing techniques in wireless relay networks". Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/10297.
Testo completoAbstract (sommario):
With the growth of wireless networks such as sensor networks and mesh networks, the challenges of sustaining higher data rates and coverage, coupled with requirement for high quality of services, need to be addressed. The use of spatial diversity proves to be an attractive option due to its ability to significantly enhance network performance without additional bandwidth or transmission power. This thesis proposes the use of cooperative wireless relays to improvise spatial diversity in wireless sensor networks and wireless mesh networks. Cooperation in this context implies that the signals are exchanged between relays for optimal performance. The network gains realised using the proposed cooperative relays for signal forwarding are significantly large, advocating the utilisation of cooperation amongst relays. The work begins with proposing a minimum mean square error (MMSE) based relaying strategy that provides improvement in bit error rate. A simplified algorithm has been developed to calculate the roots of a polynomial equation. Following this work, a novel signal forwarding technique based on convex optimisation techniques is proposed which attains specific quality of services for end users with minimal transmission power at the relays. Quantisation of signals passed between relays has been considered in the optimisation framework. Finally, a reduced complexity scheme together with a more realistic algorithm incorporating per relay node power constraints is proposed. This optimisation framework is extended to a cognitive radio environment where relays in a secondary network forward signals without causing harmful interferences to primary network users.
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Bournaka, Georgia. "Mathematical optimization and signal processing techniques for cooperative wireless networks". Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/13629.
Testo completoAbstract (sommario):
The rapid growth of mobile users and emergence of high data rate multimedia and interactive services have resulted in a shortage of the radio spectrum. Novel solutions are therefore required for future generations of wireless networks to enhance capacity and coverage. This thesis aims at addressing this issue through the design and analysis of signal processing algorithms. In particular various resource allocation and spatial diversity techniques have been proposed within the context of wireless peer-to-peer relays and coordinated base station (BS) processing. In order to enhance coverage while providing improvement in capacity, peer-to-peer relays that share the same frequency band have been considered and various techniques for designing relay coefficients and allocating powers optimally are proposed. Both one-way and two-way amplify and forward (AF) relays have been investigated. In order to maintain fairness, a signal-to-interference plus noise ratio (SINR) balancing criterion has been adopted. In order to improve the spectrum utilization further, the relays within the context of cognitive radio network are also considered. In this case, a cognitive peer-to-peer relay network is required to achieve SINR balancing while maintaining the interference leakage to primary receiver below a certain threshold. As the spatial diversity techniques in the form of multiple-input-multipleoutput (MIMO) systems have the potential to enhance capacity significantly, the above work has been extended to peer-to-peer MIMO relay networks. Transceiver and relay beamforming design based on minimum mean-square error (MSE) criterion has been proposed. Establishing uplink downlink MSE duality, an alternating algorithm has been developed. A scenario where multiple users are served by both the BS and a MIMO relay is considered and a joint beamforming technique for the BS and the MIMO relay is proposed. With the motivation of optimising the transmission power at both the BS and the relay, an interference precoding design is presented that takes into account the knowledge of the interference caused by the relay to the users served by the BS. Recognizing joint beamformer design for multiple BSs has the ability to reduce interference in the network significantly, cooperative multi-cell beamforming design is proposed. The aim is to design multi-cell beamformers to maximize the minimum SINR of users subject to individual BS power constraints. In contrast to all works available in the literature that aimed at balancing SINR of all users in all cells to the same level, the SINRs of users in each cell is balanced and maximized at different values. This new technique takes advantage of the fact that BSs may have different available transmission powers and/or channel conditions for their users.
33
Zhang, Jinfei. "Advances of Mathematical Morphology and Its Applications in Signal Processing". Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485994.
Testo completoAbstract (sommario):
This thesis describes some advances of Mathematical Morphology (MM), in order to improve the performance of MM filters in I-D signal processing, . especially in the application to power system protection. MM methodologies are founded on set-theoretic concepts and nonlinear superpositions of signals and images. The morphological operations possess outstanding geometrical properties which make it undoubted that they are efficient image processing methods. However in I-D signal processing, MM filters are not widely employed. To explore the applications of MM for I-D signal processing, our contributions in this area can be summarized in the following two aspects. Firstly, the fram.ework of the traditional signal processing methods is based on the frequency domain representation of the signal and the analysis of the operators' transfer function in the frequency domain. But to the morphological operations, their representations in the frequency domain are uncertain. In order to tackle this problem, this thesis presents our attempt to describe the weighted morphological dilation in the frequency domain. Under certain restrictions to the signal and the structuring element, weighted dilation is transformed to a mathematical expression in the frequency domain. Secondly, although the frequency domain analysis plays an important role in signal processing, the geometrical properties of a signal such as the shape of the signal cannot be ignored. MM is an effective method in dealing with such problems. In this thesis, based on the theory of Morphological Wavelet (MW), three multi-resolution signal decomposition schemes are presented. They are Multiresolution Morphological Top-Hat scheme (MMTH), Multi-resolution Morphov logical Gradient scheme (MMG) and Multi-resolution Noise Tolerant Morphological Gradient scheme (MNTMG). The MMTH scheme shows its significant effect in distinguishing symmetrical features from asymmetrical features on the waveform, which owes to its signal analysis operator: morphological Top-Hat transformation, an effective morphological technique. In this thesis, the MMTH scheme is employed in the identification of transformer magnetizing inrush curr~nt from internal fault. Decomposing the signal by MMTH, the asymmetrical features of the inrush waveform are exposed, and the other irrelevant components are attenuated. The MMG scheme adopts morphological gradient, a commonly used operator for edge detection in image and signal processing, as its signal analysis / operator. The MMG scheme bears significant property in characterizing and recognizing the sudden changes with sharp peaks and valleys on the waveform. Furthermore, to the MMG scheme, by decomposing the signal into different levels, the higher the level is processed, the more details of the sudden changes are revealed. In this thesis, the MMG scheme is applied for the design of fault locator of power transmission lines, by extracting the transient features directly from fault-generated transient signals. The MNTMG decomposition scheme can effectively reduce the noise and extract transient features at the same time. In this thesis, the MNTMG scheme is applied to extract the fault generated transient wavefronts from noise imposed signals in the application of fault location of power transmission lines. The proposed contributions focus on the effect of weighted dilation in the frequency domain, constructions of morphological multi-resolution decomposition schemes and their applications in power systems.
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Bengtsson, Mats. "Antenna array signal processing for high rank data models". Doctoral thesis, KTH, Signaler, sensorer och system, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2903.
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Noland, Katy C. "Computational tonality estimation : signal processing and hidden Markov models". Thesis, Queen Mary, University of London, 2009. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8492.
Testo completoAbstract (sommario):
This thesis investigates computational musical tonality estimation from an audio signal. We present a hidden Markov model (HMM) in which relationships between chords and keys are expressed as probabilities of emitting observable chords from a hidden key sequence. The model is tested first using symbolic chord annotations as observations, and gives excellent global key recognition rates on a set of Beatles songs. The initial model is extended for audio input by using an existing chord recognition algorithm, which allows it to be tested on a much larger database. We show that a simple model of the upper partials in the signal improves percentage scores. We also present a variant of the HMM which has a continuous observation probability density, but show that the discrete version gives better performance. Then follows a detailed analysis of the effects on key estimation and computation time of changing the low level signal processing parameters. We find that much of the high frequency information can be omitted without loss of accuracy, and significant computational savings can be made by applying a threshold to the transform kernels. Results show that there is no single ideal set of parameters for all music, but that tuning the parameters can make a difference to accuracy. We discuss methods of evaluating more complex tonal changes than a single global key, and compare a metric that measures similarity to a ground truth to metrics that are rooted in music retrieval. We show that the two measures give different results, and so recommend that the choice of evaluation metric is determined by the intended application. Finally we draw together our conclusions and use them to suggest areas for continuation of this research, in the areas of tonality model development, feature extraction, evaluation methodology, and applications of computational tonality estimation.
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Said, Maya Rida 1976. "Signal processing in biological cells : proteins, networks, and models". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30165.
Testo completoAbstract (sommario):
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 202-210).
This thesis introduces systematic engineering principles to model, at different levels of abstraction the information processing in biological cells in order to understand the algorithms implemented by the signaling pathways that perform the processing. An example of how to emulate one of these algorithms in other signal processing contexts is also presented. At a high modeling level, the focus is on the network topology rather than the dynamical properties of the components of the signaling network. In this regime, we examine and analyze the distribution and properties of the network graph. Specifically, we present a global network investigation of the genotype/phenotype data-set recently developed for the yeast Saccharomyces cerevisiae from exposure to DNA damaging agents, enabling explicit study of how protein-protein interaction network characteristics may be associated with phenotypic functional effects. The properties of several functional yeast networks are also compared and a simple method to combine gene expression data with network information is proposed to better predict pathophysiological behavior. At a low level of modeling, the thesis introduces a new framework for modeling cellular signal processing based on interacting Markov chains. This framework provides a unified way to simultaneously capture the stochasticity of signaling networks in individual cells while computing a deterministic solution which provides average behavior. The use of this framework is demonstrated on two classical signaling networks: the mitogen activated protein kinase cascade and the bacterial chemotaxis pathway. The prospects of using cell biology as a metaphor for signal processing are also considered in a preliminary way by presenting a surface mapping algorithm based on bacterial chemotaxis.
by Maya Rida Said.
Sc.D.
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Marmin, Arthur. "Rational models optimized exactly for solving signal processing problems". Electronic Thesis or Diss., université Paris-Saclay, 2020. http://www.theses.fr/2020UPASG017.
Testo completoAbstract (sommario):
Une vaste classe de problèmes d'optimisation non convexes est celle de l'optimisation rationnelle. Cette dernière apparaît naturellement dans de nombreux domaines tels que le traitement du signal ou le génie des procédés. Toutefois, trouver les optima globaux pour ces problèmes est difficile. Une approche récente, appelée la hiérarchie de Lasserre, fournit néanmoins une suite de problèmes convexes assurée de converger vers le minimum global. Cependant, cette approche représente un défi calculatoire du fait de la très grande dimension de ses relaxations. Dans cette thèse, nous abordons ce défi pour divers problèmes de traitement du signal.Dans un premier temps, nous formulons la reconstruction de signaux parcimonieux en un problème d'optimisation rationnelle. Nous montrons alors que ce dernier possède une structure que nous exploitons afin de réduire la complexité des relaxations associées. Nous pouvons ainsi résoudre plusieurs problèmes pratiques comme la restoration de signaux de chromatographie. Nous étendons également notre méthode à la restoration de signaux dans différents contextes en proposant plusieurs modèles de bruit et de signal. Dans une deuxième partie, nous étudions les relaxations convexes générées par nos problèmes et qui se présentent sous la forme de problèmes d'optimisation semi-définie positive de très grandes dimensions. Nous considérons plusieurs algorithmes basés sur les opérateurs proximaux pour les résoudre efficacement.La dernière partie de cette thèse est consacrée au lien entre les problèmes d'optimisation polynomiaux et la décomposition de tenseurs symétriques. En effet, ces derniers peuvent être tous deux vus comme une instance du problème des moments. Nous proposons ainsi une méthode de détection de rang et de décomposition pour les tenseurs symétriques basée sur les outils connus en optimisation polynomiale. Parallèlement, nous proposons une technique d'extraction robuste des solutions d'un problème d'optimisation poylnomiale basée sur les algorithmes de décomposition de tenseurs. Ces méthodes sont illustrées sur des problèmes de traitement du signalA wide class of nonconvex optimization problem is represented by rational optimization problems. The latter appear naturally in many areas such as signal processing or chemical engineering. However, finding the global optima of such problems is intricate. A recent approach called Lasserre's hierarchy provides a sequence of convex problems that has the theoretical guarantee to converge to the global optima. Nevertheless, this approach is computationally challenging due to the high dimensions of the convex relaxations. In this thesis, we tackle this challenge for various signal processing problems.First, we formulate the reconstruction of sparse signals as a rational optimization problem. We show that the latter has a structure that we wan exploit in order to reduce the complexity of the associated relaxations. We thus solve several practical problems such as the reconstruction of chromatography signals. We also extend our method to the reconstruction of various types of signal corrupted by different noise models.In a second part, we study the convex relaxations generated by our problems which take the form of high-dimensional semi-definite programming problems. We consider several algorithms mainly based on proximal operators to solve those high-dimensional problems efficiently.The last part of this thesis is dedicated to the link between polynomial optimization and symmetric tensor decomposition. Indeed, they both can be seen as an instance of the moment problem. We thereby propose a detection method as well as a decomposition algorithm for symmetric tensors based on the tools used in polynomial optimization. In parallel, we suggest a robust extraction method for polynomial optimization based on tensor decomposition algorithms. Those methods are illustrated on signal processing problems
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Inaba, Yosuke. "Radar target imaging using time-reversed processing". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA397112.
Testo completoAbstract (sommario):
Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, Sept. 2001.Thesis advisor: Morgan, Michael A. "September 2001." Includes bibliographical references (p. 87-88). Also Available in print.
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Archer, Cynthia. "A framework for representing non-stationary data with mixtures of linear models /". Full text open access at:, 2002. http://content.ohsu.edu/u?/etd,585.
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Boman, Katarina. "Low-angle estimation : Models, methods and bounds". Licentiate thesis, Uppsala universitet, Avdelningen för systemteknik, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-85998.
Testo completoAbstract (sommario):
In this work we study the performance of elevation estimators and lower bounds on the estimation error variance for a low angle target in a smooth sea scenario using an array antenna. The article is structured around some key assumptions on multipath knowledge, signal parameterization and noise covariance, giving the reader a framework in which Maximum Likelihood estimators exploiting different á priori information can be found. The crucial factor that determines the estimator accuracy is the multipath modeling, and there are three alternative levels of knowledge that can be used: 1) two unknown target locations 2) the target and its corresponding sea-reflection are related via simple geometry 3) the sea-reflection coefficient is known as a function of grazing angle. A compact expression for the Cramér–Rao lower bound is derived, including all special cases of the key assumptions. We prove that the Cramér–Rao bound is highly dependent on the multipath model, while it is the same for the different signal parameterizations and that it is independent of the noise covariance. However, the Cramér–Rao bound is sometimes too optimistic and not achievable. The tighter Barankin bound is derived to predict the threshold behavior seen at low SNR. At high SNR the Barankin bound coincides with the Cramér–Rao bound. Simulations show that the Maximum Likelihood methods are statistically efficient and achieve the theoretical lower bound on error variance, in case of high enough SNR. The bounds are also useful tools to design an improved array structure that can give better performance than the standard uniform linear array structure. The influence of the number of sensors and the number of snapshots on the error variance is also studied, showing the rate of improvement with more sensors or snapshots. Finally we discuss the use of multiple frequencies, which is mainly a tool for suppressing ambiguities. We show for which signal models it provides improved performance.
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Mahata, Kaushik. "Identification of dynamic errors-in-variables models". Licentiate thesis, Uppsala universitet, Avdelningen för systemteknik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-86301.
Testo completoAbstract (sommario):
The problem of identifying dynamic errors-in-variables models is of fundamental interest in many areas like process control, array signal processing, astronomical data reduction. In recent years, this field has received increased attention of the research community. In this thesis, some time domain and frequency domain approaches for identifying the errors-in-variables model is studied. The first chapter gives an overview of various methods for identifying dynamic errors-in-variables systems. Several approaches are classified and a qualitative comparison of different existing methods is also presented. The second chapter deals with instrumental variables based approaches. The least squares and the total least squares methods of solving the Yule–Walker equation is of central interest here. The methods are compared from the view point of asymptotic performance, numerical robustness and computation. The method presented in the third chapter uses prefiltered data. The input-output data is passed through a pair of user defined prefilters and the output data from the prefilters is subjected to a least-squares like algorithm. Compared to the IV approach, the proposed method shows a significant improvement in the small-sample properties of the MA parameter estimates, without any increase in the computational load. In the fourth chapter, we show that the two-dimensional process composed of the input-output data admits a finite order ARMA representation. Then we propose a parametric identification algorithm and another non-parametric identification method based on the ARMA representation.
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Bhikkaji, Bharath. "Model Reduction and Parameter Estimation for Diffusion Systems". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4252.
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Liu, Yi. "A study of mathematical modelling and signal processing of cerebral autoregulation". Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273880.
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Giddens, Spencer. "Applications of Mathematical Optimization Methods to Digital Communications and Signal Processing". BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8601.
Testo completoAbstract (sommario):
Mathematical optimization is applicable to nearly every scientific discipline. This thesis specifically focuses on optimization applications to digital communications and signal processing. Within the digital communications framework, the channel encoder attempts to encode a message from a source (the sender) in such a way that the channel decoder can utilize the encoding to correct errors in the message caused by the transmission over the channel. Low-density parity-check (LDPC) codes are an especially popular code for this purpose. Following the channel encoder in the digital communications framework, the modulator converts the encoded message bits to a physical waveform, which is sent over the channel and converted back to bits at the demodulator. The modulator and demodulator present special challenges for what is known as the two-antenna problem. The main results of this work are two algorithms related to the development of optimization methods for LDPC codes and the two-antenna problem. Current methods for optimization of LDPC codes analyze the degree distribution pair asymptotically as block length approaches infinity. This effectively ignores the discrete nature of the space of valid degree distribution pairs for LDPC codes of finite block length. While large codes are likely to conform reasonably well to the infinite block length analysis, shorter codes have no such guarantee. Chapter 2 more thoroughly introduces LDPC codes, and Chapter 3 presents and analyzes an algorithm for completely enumerating the space of all valid degree distribution pairs for a given block length, code rate, maximum variable node degree, and maximum check node degree. This algorithm is then demonstrated on an example LDPC code of finite block length. Finally, we discuss how the result of this algorithm can be utilized by discrete optimization routines to form novel methods for the optimization of small block length LDPC codes. In order to solve the two-antenna problem, which is introduced in greater detail in Chapter 2, it is necessary to obtain reliable estimates of the timing offset and channel gains caused by the transmission of the signal through the channel. The timing offset estimator can be formulated as an optimization problem, and an optimization method used to solve it was previously developed. However, this optimization method does not utilize gradient information, and as a result is inefficient. Chapter 4 presents and analyzes an improved gradient-based optimization method that solves the two-antenna problem much more efficiently.
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Wong, Chi-kwong, e 黃志光. "Lane-based optimization method for traffic signal design". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31246096.
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Ннамене, Крістофер Чізоба. "Комп’ютерна онтологія предметної області «Моделювання та опрацювання циклічних сигналів»". Diss., Тернопільський національний технічний університет ім. Івана Пулюя, 2021. http://elartu.tntu.edu.ua/handle/lib/36019.
Testo completoAbstract (sommario):
Дисертація присвячена вирішенню актуального наукового завдання розробки концептуальних, формальних та машинно-інтерпретовних моделей подання та організації знань в інтегрованому онтоорієнтованому інформаційному середовищі для моделювання та опрацювання циклічних сигналів в рамках теорії циклічних функціональних відношень, а також побудові на їх основі прототипу комп’ютерної онтології предметної області «Моделювання та опрацювання циклічних сигналів», що є ядром бази знань таких онтоорієнтованих інформаційних систем як інформаційна довідкова система, експертна система підтримки прийняття рішень та система комп’ютерного моделювання та опрацювання циклічних сигналів.The dissertation is devoted to the solution of the actual scientific problem of development of conceptual, formal and machine-interpretive models of representation and organization of knowledge in the integrated onto - oriented information environment for Modeling and processing of cyclic signals within the theory of cyclic functional relations. "Modeling and processing of cyclic signals" is the core knowledge base of such onto-oriented information systems as information reference systems, expert decision support systems, computer modeling and processing of cyclic signals.
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Liu, Li. "Ground vehicle acoustic signal processing based on biological hearing models". College Park, Md. : University of Maryland, 1999. http://techreports.isr.umd.edu/reports/1999/MS%5F99-6.pdf.
Testo completoAbstract (sommario):
Thesis (M.S.) -- University of Maryland, College Park, 1999.Thesis research directed by Institute for Systems Research. "M.S. 99-6." Includes bibliographical references (leaves 75-78). Available also online as a PDF file via the World Wide Web.
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Glenn, Dickins, e glenn dickins@dolby com. "Applications of Continuous Spatial Models in Multiple Antenna Signal Processing". The Australian National University. Research School of Information Sciences and Engineering, 2008. http://thesis.anu.edu.au./public/adt-ANU20080702.222814.
Testo completoAbstract (sommario):
This thesis covers the investigation and application of continuous spatial models for multiple antenna signal processing. The use of antenna arrays for advanced sensing and communications systems has been facilitated by the rapid increase in the capabilities of digital signal processing systems. The wireless communications channel will vary across space as different signal paths from the same source combine and interfere. This creates a level of spatial diversity that can be exploited to improve the robustness and overall capacity of the wireless channel. Conventional approaches to using spatial diversity have centered on smart, adaptive antennas and spatial beam forming. Recently, the more general theory of multiple input, multiple output (MIMO) systems has been developed to utilise the independent spatial communication modes offered in a scattering environment.¶
Underlying any multiple antenna system is the basic physics of electromagnetic wave propagation. Whilst a MIMO system may present a set of discrete inputs and outputs, each antenna element must interact with the underlying continuous spatial field. Since an electromagnetic disturbance will propagate through space, the field at different positions in the space will be interrelated. In this way, each position in the field cannot assume an arbitrary independent value and the nature of wave propagation places a constraint on the allowable complexity of a wave-field over space. To take advantage of this underlying physical constraint, it is necessary to have a model that incorporates the continuous nature of the spatial wave-field. ¶This thesis investigates continuous spatial models for the wave-field. The wave equation constraint is introduced by considering a natural basis expansion for the space of physically valid wave-fields. This approach demonstrates that a wave-field over a finite spatial region has an effective finite dimensionality. The optimal basis for representing such a field is dependent on the shape of the region of interest and the angular power distribution of the incident field. By applying the continuous spatial model to the problem of direction of arrival estimation, it is shown that the spatial region occupied by the receiver places a fundamental limit on the number and accuracy with which sources can be resolved. Continuous spatial models also provide a parsimonious representation for modelling the spatial communications channel independent of specific antenna array configurations. The continuous spatial model is also applied to consider limits to the problem of wireless source direction and range localisation.
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Nguyen, Hang Tuan. "Numerical investigations of some mathematical models of the diffusion MRI signal". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112016/document.
Testo completoAbstract (sommario):
Ma thèse porte sur la relation entre la microstructure des tissus et le signal macroscopique d'imagerie par résonance magnétique de diffusion (IRMd). Les estimations des paramètres de tissus provenant de signaux mesurées expérimentalement est très important dans l'IRMd. En dépit d'une histoire de la recherche intensive dans ce domaine depuis longtemps, de nombreux aspects de ce problème inverse restent mal compris. Nous avons proposé et testé une solution approchée à ce problème, dans lequel le signal d'IRMd est d'abord approché par un modèle macroscopique appropriée, puis le paramètres effectifs de ce modèle sont estimés.Nous avons étudié deux modèles macroscopiques du signal d'IRMd. Le premier est le modèle Karger qui suppose une certaine forme de (macroscopique) diffusion de compartiments multiples et les échanges inter-compartiment, mais est soumis à la restriction d'impulsion étroite sur les impulsions de gradient de champ magnétique diffusion codant. Le deuxième est un modèle ODE de plusieurs aimantations compartiment obtenus à partir de l'homogénéisation mathématique de l'équation de Bloch-Torrey, qui n'est pas soumis à la restriction d'impulsion étroite.Tout d'abord, nous avons étudié la validité de ces modèles macroscopiques en comparant le signal d'IRMd proposée par le modèle Karger et le modèle ODE avec le signal d'IRMd de diffusion simulé sur certaines geometries de tissu relativement complexes en résolvant l'équation de Bloch-Torrey en cas de membranes semi-perméables cellule biologique. Nous avons conclu que la validité de ces deux modèles macroscopiques est limitée au cas où la diffusion dans chaque compartiment est effectivement gaussien et où l'échange inter-compartimentale peut être représenté par des termes cinétiques de premier ordre standard.Deuxièmement, en supposant que les conditions ci-dessus sur la diffusion compartimentale et l'échange inter-compartiment sont satisfaits, nous avons résolu le problème des moindres carrés associée à monter les paramètres du modèle Karger et du modèle ODE au signal simulé d'IRMd obtenu en résolvant l'équation de Bloch-Torrey microscopique. Parmi divers paramètres efficaces, nous avons examiné les fractions volumiques des compartiments intra-cellulaires et extra-cellulaires, la perméabilité de la membrane, la taille moyenne des cellules, la distance inter-cellulaire, ainsi que des coefficients de diffusion apparents. Nous avons commencé par étudier la faisabilité de la méthod des moindres carrés pour les deux groupes de geometries de tissu relativement simples. Pour le premier groupe, dans lequel les domaines sont constitués de cellules identiques ou sphériques de taille variable noyées dans l'espace extra-cellulaire, nous avons conclu que problème d'estimation de paramètres peut être résolu robuste, même en présence de bruit. Dans le second groupe, on a considéré les cellules cylindriques parallèles, qui peuvent être couverts par une couche de membrane d'épaisseur, et noyés dans l'espace extra-cellulaire. Dans ce cas, la qualité de l'estimation des paramètres dépendant fortement de la quantité de la structure cellulaire est allongée dans la direction du gradient. Dans la pratique, l'orientation des cellules allongées n'est pas de priori connue, de plus, les tissus biologiques peuvent contenir des structures allongées orientées de manière aléatoire et également en mélange avec d'autres éléments compacts (par exemple, les axones et les cellules gliales). Cette situation a été étudiée numériquement sur notre domaine le plus complexe dans lequel les couches de cellules cylindriques dans différentes directions sont mélangés avec des couches de cellules sphériques. Nous avons vérifié que certains paramètres peuvent encore être estimés assez fidèlement tandis que l'autre reste inaccessible. Dans tous les cas considérés, le modèle ODE a fourni des estimations plus précises que le modèle KargerMy thesis focused on the relationship between the tissue microstructure and the macroscopic dMRI signal. Inferring tissue parameters from experimentally measured signals is very important in diffusion MRI. In spite of a long standing history of intensive research in this field, many aspects of this inverse problem remain poorly understood. We proposed and tested an approximate solution to this problem, in which the dMRI signal is first approximated by an appropriate macrosopic model and then the effective parameters of this model are estimated.We investigated two macroscopic models of the dMRI signal. The first is the Kärger model that assumes a certain form of (macroscopic) multiple compartmental diffusion and intercompartment exchange, but is subject to the narrow pulse restriction on the diffusion-encoding magnetic field gradient pulses. The second is an ODE model of the multiple compartment magnetizations obtained from mathematical homogenization of the Bloch-Torrey equation, that is not subject to the narrow pulse restriction.First, we investigated the validity of these macroscopic models by comparing the dMRI signal given by the Kärger and the ODE models with the dMRI signal simulated on some relatively complex tissue geometries by solving the Bloch-Torrey equation in case of semi-permeable biological cell membranes. We concluded that the validity of both macroscopic models is limited to the case where diffusion in each compartment is effectively Gaussian and where the inter-compartmental exchange can be accounted for by standard first-order kinetic terms.Second, assuming that the above conditions on the compartmental diffusion and intercompartment exchange are satisfied, we solved the least squares problem associated with fitting the Kärger and the ODE model parameters to the simulated dMRI signal obtained by solving the microscopic Bloch-Torrey equation. Among various effective parameters, we considered the volume fractions of the intra-cellular and extra-cellular compartments, membrane permeability, average size of cells, inter-cellular distance, as well as apparent diffusion coefficients. We started by studying the feasibility of the least squares solution for two groups of relatively simple tissue geometries. For the first group, in which domains consist of identical or variably-sized spherical cells embedded in the extra-cellular space, we concluded that parameters estimation problem can be robustly solved, even in the presence of noise. In the second group, we considered parallel cylindrical cells, which may be covered by a thick membrane layer, and embedded in the extra-cellular space. In this case, the quality of parameter estimation strongly depends on how much the cellular structure is elongated in the gradient direction. In practice, the orientation of elongated cells is not known a priori; moreover, biological tissues may contain elongated structures randomly oriented and also mixed with other compact elements (e.g., axons and glial cells). This situation has been numerically investigated on our most complicated domain in which layers of cylindrical cells in various directions are mixed with layers of spherical cells. We checked that certain parameters can still be estimated rather accurately while the other remains inaccessible. In all considered cases, the ODE model provided more accurate estimates than the Kärger model
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Mahata, Kaushik. "Estimation Using Low Rank Signal Models". Doctoral thesis, Uppsala University, Department of Information Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3844.
Testo completoAbstract (sommario):
Designing estimators based on low rank signal models is a common practice in signal processing. Some of these estimators are designed to use a single low rank snapshot vector, while others employ multiple snapshots. This dissertation deals with both these cases in different contexts.
Separable nonlinear least squares is a popular tool to extract parameter estimates from a single snapshot vector. Asymptotic statistical properties of the separable non-linear least squares estimates are explored in the first part of the thesis. The assumptions imposed on the noise process and the data model are general. Therefore, the results are useful in a wide range of applications. Sufficient conditions are established for consistency, asymptotic normality and statistical efficiency of the estimates. An expression for the asymptotic covariance matrix is derived and it is shown that the estimates are circular. The analysis is extended also to the constrained separable nonlinear least squares problems.
Nonparametric estimation of the material functions from wave propagation experiments is the topic of the second part. This is a typical application where a single snapshot vector is employed. Numerical and statistical properties of the least squares algorithm are explored in this context. Boundary conditions in the experiments are used to achieve superior estimation performance. Subsequently, a subspace based estimation algorithm is proposed. The subspace algorithm is not only computationally efficient, but is also equivalent to the least squares method in accuracy.
Estimation of the frequencies of multiple real valued sine waves is the topic in the third part, where multiple snapshots are employed. A new low rank signal model is introduced. Subsequently, an ESPRIT like method named R-Esprit and a weighted subspace fitting approach are developed based on the proposed model. When compared to ESPRIT, R-Esprit is not only computationally more economical but is also equivalent in performance. The weighted subspace fitting approach shows significant improvement in the resolution threshold. It is also robust to additive noise.