O conhecimento da fenologia é baseado nas observações de períodos de desenvolvimento da planta. Mudanças intra e interanuais na temperatura e precipitação podem influenciar diretamente as diferentes fases da fenologia, assim como as condições de umidade dos diferentes tipos de solo ao qual a vegetação está associada. O sensoriamento remoto é uma ferramenta que torna possível a aquisição de informações para análise espacial e temporal da vegetação. Este trabalho apresenta um estudo sobre as variações da resposta espectral da vegetação campestre natural na Área de Proteção Ambiental (APA) do Ibirapuitã, localizada no bioma Pampa, avaliando suas relações com os elementos do clima. Para isso, a metodologia compreendeu a coleta de dados climáticos de temperatura média do ar e precipitação pluvial; dados orbitais a partir de imagens de média resolução espacial do sensor MODIS para o período de 2000 a 2009, com posterior estimativa da correlação estatística entre estes dados. Além disso, utilizou-se o produto SRTM para auxiliar definição da grade amostral, em função da altimetria e solo. Os resultados mostraram os períodos de crescimento/desenvolvimento da vegetação campestre natural associados às estações do ano, com um período de crescimento nas estações quentes, diminuição da reflectância na região espectral do visível e aumento da reflectância no infravermelho próximo. Observou-se também, um período de senescência na estação fria do ano, onde o comportamento espectral da vegetação apresenta um aumento da reflectância na região espectral do visível e diminuição da reflectância no infravermelho próximo. As diferenças na reflectância da vegetação para cada tipo de solo foi observada para solos mais profundos, capazes de armazenar mais água. De maneira geral, verificou-se que a resposta espectral da vegetação campestre apresentou relação com as variações de temperatura média do ar e precipitação na região, respondendo às variáveis meteorológicas com um atraso aproximado de dezesseis (16) dias. Verificou-se assim que dados MODIS do infravermelho próximo, são adequados para monitorar o início da estação de máximo crescimento da vegetação campestre natural da APA do Ibirapuitã que se inicia na primavera. Este período está relacionado com a temperatura média do ar. / The knowledge of phenology is based on observations of periods of plant development. Inter-annual changes in temperature and rainfall may directly influence the different stages of phenology, as well as the moisture conditions of different soil types to which the vegetation is associated. Remote sensing is a tool which allows the acquisition of information for spatial and temporal analysis of vegetation. This work has aimed to study the variations of the natural grassland spectral response in the Ibirapuitã environmental protected area, which belongs to the Pampa biome, evaluating their relationship with the elements of climate. The methodology has consisted of collection of meteorological data, such as air temperature and rainfall, and orbital data from medium spatial resolution MODIS images, which covered the period from 2000 to 2009. It has also performed a statistical correlation among those data. In addition, a SRTM-defining product has employed as sampling grid, depending on elevation and soil. The results have showed periods of growth and development of natural grassland vegetation associated with the seasons, with a growth period during the warm seasons, and with a decrease of the reflectance in the visible spectrum and with an increase in the near infrared one. It was also observed a period of senescence during the cold season, where the spectral characteristics of the vegetation present a increase of the reflectance in the visible spectrum and with an decrease in the near infrared one. The differences in reflectance of vegetation in each soil type have showed most prominent in the deeper ones, which have a large water storage capacity. Overall, it has been observed a tight coupling between the spectral response of grassland vegetation and changes in air temperature and rainfall in the study area, so that the former has responded to the meteorological variables with a delay of approximately sixteen (16) days. Near-infrared MODIS data have been showed suitable to monitor the beginning of the season of maximum growth of natural grassland vegetation in the APA of the Ibirapuitã of which begins in spring. This period is mainly related to air temperature.

Orientadores: Carlos Roberto de Souza Filho, Teodoro Isnard Ribeiro de Almeida / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-17T04:04:23Z (GMT). No. of bitstreams: 1 Quiterio_GiulianaClariceMercuri_D.pdf: 42396730 bytes, checksum: 61bf622657c16e3ea121d243ff8a79c3 (MD5) Previous issue date: 2010 / Resumo: Essa pesquisa compreende a aplicação de técnicas de sensoriamento remoto (SR) no aprimoramento dos sistemas de detecção indireta de vazamentos de pequeno porte (<1% de pressão e vazão) em dutos de transporte de hidrocarbonetos (HCs). O objetivo geral do estudo foi verificar a possibilidade de detecção de alterações botânicas relacionadas à presença de gasolina (GSL) e diesel (DSL) no solo, através de respostas espectrais de espécies vegetais, no intervalo de 400 a 2500nm do espectro eletromagnético. As espécies abordadas compreendem três grupos distintos, entre os quais uma gramínea (Brachiaria brizantha (BR)), uma leguminosa (Neonotonia wightii (SJ)) e uma espécie de habito arbóreo (Eucalyptus camaldulensis (EUC)). A gramínea e a leguminosa são perenes e têm ampla ocorrência no território nacional. O ensaio foi realizado em casa de vegetação contendo 45 lisímetros, nos quais contaminações controladas e periódicas foram realizadas buscando-se simular, em escala reduzida, o sistema solo-vegetação de locais com vazamentos indetectáveis pelos sistemas usuais de monitoramento. As variáveis analisadas, incluindo altura, massa da matéria seca e fresca da parte aérea e raízes, conteúdo de pigmentos, amido, açúcar total, nutrição mineral da vegetação e fertilidade do solo, foram correlacionadas com as propriedades de refletância das folhas. Os resultados mostraram que as três espécies vegetais apresentaram alterações espectrais e morfo-fisiológicas relacionadas à presença de GSL e DSL no solo, porém, cada qual com volume de HCs e tempo de exposição distintos. A GSL foi o contaminante mais agressivo e as respostas fisiológicas e espectrais nas plantas submetidas a esse hidrocarboneto foram observadas mais precocemente quando comparada àquelas contaminadas por DSL. Entre as culturas estudadas, a SJ mostrou resultados mais significativos e anomalias em sua resposta espectral puderam ser observadas desde a primeira dose de contaminação. Além das alterações espectrais, a forte queda da massa da matéria da parte aérea proporcionou fácil detecção de áreas contaminadas, inclusive por sensores imageadores multiespecrais e, principalmente, hiperespectrais. A BR também apresentou resultados satisfatórios, especialmente com relação às alterações espectrais, que podem ser facilmente detectadas e diferenciadas do background nos lisímetros de controle, sem contaminação. O EUC mostrou ser a espécie mais resistente a contaminação e respostas espectrais evidentes foram observadas somente após a aplicação de quantidades maiores de HCs no solo. As três espécies apresentaram alterações específicas na região do SWIR em resposta à contaminação, correlacionadas com a metabolização de compostos de sacarídeos, podendo-se especificar padrões de estresse correlacionados com a presença dos HCs no solo. Desta forma, a pesquisa contemplou o objetivo de indicar um espécie vegetal mais suscetível à presença de baixas concentrações de HCs no solo e caracterizar espectralmente as alterações decorrente desta contaminação, possibilitando o desenvolvimento de novas técnicas de monitoramento fino da malha dutoviária nacional brasileira, seja através de sensores portáteis, aerotrasnportados ou orbitais. / Abstract: This research involves the application of remote sensing (RS) data and techniques to improve the indirect detection of small leakages (i.e. <1% in pressure and flow) through hydrocarbon pipelines. The overall objective of the study was to investigate the possibility to detect botanical and attuned visible and infrared (400-2500 nm) spectral changes induced by plant growth on soils contaminated with gasoline (GSL) and diesel (DSL). The species addressed include three distinct groups: a grass specie (Brachiaria brizantha (BR)), a leguminous specie (Neonotonia wightii (SJ)) and type of forest tree (Eucalyptus camaldulensis (EUC)). Both the grass and leguminous species are perennials and have a wide occurrence in Brazil. The leakage experiments were conducted in a greenhouse containing 45 lysimeters, where controlled contaminations were carried out periodically. The notion was to simulate a a contaminated soilvegetation system at reduced scale mimicking an underground, small and slow leakage, which is undetectable by the usual monitoring systems. The analyzed variables, including height, mass of dry and fresh shoot and roots, pigment content, starch, total sugar, mineral nutrition of the vegetation and soil fertility, were correlated with the reflectance properties of plant leaves. The results indicated that the three plant species showed spectral and morphophysiological changes related to the presence of GSL and DSL in the soil, however, each with a specific volume of HCs and different exposure time. The GSL proved to be a more aggressive contaminant. Physiological and spectral responses of plants grown under this hydrocarbon were observed earlier when compared to those contaminated by DSL. Among the crops studied, SJ showed results that are more significant. Anomalous spectral response could be observed since the first dose of contamination applied to this leguminous specie. In addition to the spectral changes, the sharp decrease of the mass of shoot matter provided easy detection of contaminated areas. The same detection showed plausible on spectra simulated to the bandwidth of multispectral and mostly hyperspectral imaging sensors. BR also showed satisfactory results, particularly with respect to spectral changes, which can be easily traced and differentiated from the background (i.e., measurements taken on lysimeters containing plants without contamination). The EUC was found to be the specie most resistant to contamination and spectral responses were only evident after the application of larger amounts of HCs in the soil. The three species showed specific changes in the SWIR region in response to HC contamination. Such changes are connected with the metabolism of saccharides compounds, which seem to cause specified stress patterns correlated with the presence of HCs in the soil. Thus, through this research it was possible to indicate plant species most susceptible to indirectly respond to the presence of low concentrations of HCs in soil and spectrally characterize the botanical changes resulting from this contamination. This enables the development of a new and detailed surveillance method for monitoring the Brazilian pipeline networks, either through portable, airborne or orbital sensors. / Doutorado / Geologia e Recursos Naturais / Doutor em Ciências

Orientador: Jose Maria Campos dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T16:32:14Z (GMT). No. of bitstreams: 1 Pereira_FlavioNunes_M.pdf: 35059535 bytes, checksum: bdcc933434fe0ba550e4d1291079e6c5 (MD5) Previous issue date: 2009 / Resumo: Este trabalho investiga o problema de propagação de ondas em estruturas do tipo barra com modelos de alta ordem. O enforque principal do trabalho concentra-se na implementação de modelos numéricos que representem o fenômeno da propagação de ondas em barras saudáveis e danificadas por uma trinca. Para a investigação do problema utilizou-se o Método do Elemento Espectral, o qual consiste em uma solução analítica das equações diferenciais da onda no domínio da freqüência utilizando-se técnicas matriciais similares ao Método dos Elementos Finitos. Quatro modelos de barra, com diferentes modos de propagação foram implementados computacionalmente em linguagem Matlab®: o modelo elementar; modelo de Love ou do primeiro modo; o modelo de Mindlin-Herrmann ou de dois modos; e o modelo de Mindlin-McNiven ou dos três modos. Para cada modelo de barra foram implementados os elementos espectrais: saudável finito, saudável semi-finito e trincado. Para avaliar o comportamento da onda durante sua propagação nas estruturas analisadas, diferentes exemplos numéricos foram feitos e validados através de comparações com resultados similares encontrados na literatura. As estruturas são excitadas por forças impulsivas construídas por uma onda senoidal modulada com uma janela triangular. Os resultados confirmam que os modelos de elemento espectral representam muito bem o fenômeno da propagação de onda em uma estrutura e também podem ser usados como uma ferramenta eficiente para a localização de trincas. / Abstract: This work investigates the wave propagation problem in high order rod type structures. The main approach is the implementation of numerical models that represent the phenomenon of wave propagation in healthy and cracked rods. The investigation uses the Spectral Element Method, which consists of an analytical solution of wave deferential equations in the frequency domain using matrix techniques similar to the Finite Element Method. Four rod models with diferent propaga- tion modes were implemented computationally in Matlab® language: the elementary model; Love's model or the first model, Mindlin-Herrmann's model or the two model, and Mindlin- McNiven's model or the three-model. For each type of rod spectral elements were implemented: finite he-althy, throw-o® healthy and cracked. To evaluate the wave propagation behavior in the analyzed structures, diferent numerical examples were made and validated through comparisons with si-milar results from the literature. The structures are excited by impulsive forces built by a sine wave modulated with a triangular window. The results confirm that the Spectral Element Method represent the phenomenon of the wave propagation very well in a structure and they can also be used as an efficient tool for the location of crack. / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Evandro Conforti / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-23T02:46:09Z (GMT). No. of bitstreams: 1 Galdieri_FlavioJose_D.pdf: 39790965 bytes, checksum: 18db9fa30a7997dc5b78aedb2c47a930 (MD5) Previous issue date: 2013 / Resumo: Analisa-se neste trabalho o efeito que o ruído acústico incidente sobre a fibra óptica tem na medida da largura de linha espectral do laser HeNe, utilizando experimentalmente o método auto-homódino com um interferômetro de Mach-Zehnder desbalanceado. O interferômetro tem um ramo com dois quilômetros mais longo que o outro, sendo a fibra enrolada em forma de bobina. As fases dos feixes da luz do laser são descorrelacionadas por atraso relativo dado pela bobina. Por razões práticas a linha de atraso foi construída com comprimento muito menor que o requerido, o que não atende a condição de não-correlação, na qual o tempo de atraso relativo é maior que o tempo de coerência do laser. Os resultados experimentais mostram que a linha espectral tem alta correlação com uma linha lorentziana e que a linha é alargada por intensificação do ruído acústico sobre a bobina de fibra. A abordagem teórica considera que o ruído acústico sobre a bobina tem os efeitos de levar o interferômetro a um regime quasi-coerente, descorrelacionando parcialmente as fases e de alargar a linha espectral por intensificação do ruído acústico nas ressonâncias da bobina. Simula-se o alargamento da linha com introdução de uma modulação harmônica no interferômetro. A simulação da bobina, modelada como uma casca cilíndrica de sílica com incidência de uma onda acústica calcula a variação do índice de refração, nas frequências próprias da casca cilíndrica. A partir destes resultados calcula-se o índice de modulação da onda acústica, com a técnica da matriz de transferência e obtêm-se, no espectro simulado com modulação de fase, a linha espectral alargada. Na parte experimental, o interferômetro foi montado em câmara de vácuo para controlar a intensidade do ruído acústico. Nas medições, o ruído acústico descorrelaciona as ondas por modulação. Devido a este efeito, a linha medida tem alta correlação com uma lorentziana e largura que aumenta com a pressão, que é a hipótese do presente trabalho / Abstract: We experimentally analyze the acoustic noise effect on the measurement of the HeNe laser spectral linewidth, using an unbalanced optical fiber Mach-Zehnder interferometer, with a two kilometers longer arm. The fiber is wounded on a reel. The measured spectra with self homodyne detection is a process where the original laser signal is split, propagate in the two arms, are coupled together before detection by a photo-diode. The measured signals are non-coherent, given by the relative delay longer than the coherence time in the long arm. For practical reasons, the delay line was built with a much shorter length than required to analyze the laser line, which limits the delay to a value smaller than the coherence time. The theoretical approach here considers the acoustic noise on the longer arm forcing the interferometer system to a quasi-coherent, partially uncorrelating regime. The overall effect is a broadening of the spectral line by the enhancement of acoustic noise in coil fiber resonances. The enlargement of the spectral line is simulated using the introduction of a harmonic modulation wave in the non-coherent regime. A three-dimensional simulation of the optical fiber coil shaped like a silica cylindrical shell, with incidence of an acoustic wave, calculates the variations of refractive index in the natural frequencies of the cylindrical shell through the elasto-optic tensor. The refractive index variation of this model is applied to obtain the modulation index of the light in the fiber, using the transfer matrix technique to simulate the phase modulated spectrum. In the experimental bench, the interferometer is mounted in a vacuum chamber to control the intensity of the acoustic noise effect. The results exhibit increasing spectral linewidth with the air pressure, always preserving a high correlation with a Lorentzian line. In the simulation of the interferometer with phase modulated ligth signals, the spectral line is also broadened. The experimental results is in agreement with the hypothesis of spectral line broadening caused by phase uncorrelated waves whose uncorrelation is enhanced by the acoustic noise random effects in the interferometer long arm optical fiber reel / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

The heat content of a domain D of &Ropf;^d is defined as</sp> < p >E(s) = &int;_D u(s,x)dx, where u is the solution to the heat equation with zero initial condition and unit Dirichlet boundary condition. This thesis studies the behaviour of E(s) for small s with a particular emphasis on the case where $D$ is a planar domain whose boundary is a random Koch curve. When &part;D is spatially homogeneous, we show that we can recover the upper and lower Minkowski dimensions of &part;D from E(s). Furthermore, in some cases where the Minkowski dimension does exist, finer fluctuations can be recovered and the heat content is controlled by s^&alpha; exp{f (log(1/s)} for small s, for some positive &alpha; and some regularly varying function f. When &part;D is statistically self-similar, the heat content asymptotics are studied using a law of large numbers for the general branching process, and we show that the Minkowski dimension and content of &part;D exist and can be recovered from E(s). More precisely the heat content has an almost sure expansion E(s) = c₁ s^&alpha; N_&infin; + o(s^&alpha;), a.s. for small s, for some positive c₁ and &alpha; and a positive random variable N_&infin; with unit expectation. To study the fluctuations around these asymptotics, we prove a central limit theorem for the general branching process. The proof follows a standard Taylor expansion argument and relies on the independence built into the general branching process. The limiting distribution established here is reminiscent of those arising in central limit theorems for martingales. When &part;D is a statistically self-similar Cantor subset of &Ropf;, we discuss examples where we have and fail to have a central limit theorem for the heat content. We conclude with an open question about the fluctuations of the heat content when &part;D is a statistically self-similar Koch curve.

In Michelson interferometry, many algorithms are used to detect the number of active laser sources at any given time. Conventional FFT-based non-parametric methods are widely used for this purpose. However, non-parametric methods are not the only possible option to distinguish the peaks in a spectrum, as these methods are not the most suitable methods for short data records and for closely spaced wavelengths. This thesis aims to provide solutions to these problems. It puts forward the use of parametric methods such as autoregressive methods and harmonic methods, and proposes two new algorithms to detect the closely spaced peaks for different scenarios of optical signals in wavemeters. Various parametric algorithms are studied, and their performances are compared with non-parametric algorithms for different criteria, e.g. absolute levels, frequency resolution, and accuracy of peak positions. Simulations are performed on synthetic signals produced from specifications provided by our sponsor, i.e., a wavemeter manufacturing company.

The induction motor is a highly utilised electrical machine in industry, with the nuclear industry being no exception. A typical nuclear power station usually contains more than 1000 motors, where they are used in safety and non-safety application. The efficient and fault-free operation of this machine is critical to the safe and economical operation of any plant, including nuclear power stations. A comprehensive literature review was conducted that covered the functioning of the induction machine, its common faults and methods of detecting these faults. The Condition Based Maintenance framework was introduced in which condition monitoring of induction machines is an essential component. The main condition monitoring methods were explained with the main focus being on Motor Current Signature Analysis (MCSA) and the various methods associated with it. Three analysis methods were selected for further study, namely, Current Signature Analysis, Instantaneous Power Signature Analysis (IPSA) and Motor Square Current Signature Analysis (MSCSA). Essentially, the methodology used in this dissertation was to study the three common motor faults (bearings, stator and rotor cage) in isolation and compare the results to that of the healthy motor of the same type. The test loads as well as fault severity were varied where possible to investigate its effect on the fault detection scheme. The data was processed using an FFT based algorithm programed in MATLAB. The results of the study of the three spectral analysis techniques showed that no single technique is able to detect motor faults under all tested circumstances. The MCSA technique proved the most capable of the three techniques as it was able to detect faults under most conditions, but generally suffered poor results in inverter driven motor applications. The IPSA and MSCSA techniques performed selectively when compared to MCSA and were relatively successful when detecting the mechanical faults. The fact that the former techniques produce results at unique points in the spectrum would suggest that they are more suitable for verifying results. As part of a comprehensive condition monitoring scheme, as required by a large population of the motors on a nuclear power station, the three techniques presented in this study could readily be incorporated into the Condition Based Maintenance framework where the strengths of each could be exploited.

In this research an attempt is made at explaining the physical processes behind energy dissipation during wave breaking, through spectral analysis of the resulting sound. The size of an air bubble can be directly linked to the frequency of the sound that is heard using the simple harmonic solution to the Rayleigh–Plesset equation. It indicates the inverse relationship between frequency and bubble size. And this relationship has been used to identify wave breaking in general [MANASSEH 2006]. Now this research goes a step farther and looks at how the frequency spectrum of the sound changes with time, in an effort to understand the general pattern and from that to deduce an empirical equation that describes the breaking down of turbulence during a wave breaking event. Two main processes have been identified, with the second process having three main indicators that are necessary to evidence wave breaking. The first process is a near instantaneous shattering of the initial air bubble into much smaller metastable bubbles of a size that appears to be common for all waves independent of wave height. Then in the second process, the bubbles continue to break down following a recognisable pattern. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

The e-OPRA Implant System (Integrum AB, Sweden) is a system which employs permanently accessible implantable neuromuscular electrodes in combination with osseointegrated attachment of the prosthesis to the skeleton, in order to create a more natural control of advanced robotic upper-limb prostheses. The system enables the possibility of sensory feedback, via a cuff electrode to the ulnar nerve which allows for direct neurostimulation of the nerve. This work proposes a method using electroencephalography (EEG) to quantitatively evaluate the cognitive workload of a person controlling a prosthesis, and how said workload changes when sensory feedback is enabled. Based on previous studies on EEG and cognitive workload, the proposed methods include collecting EEG data from subjects who are performing a grasping task while listening to a selection of sounds and counting the number of times a specific tone is presented. The data is analysed using both event related potentials (ERPs) as well as spectral analysis. The method was used in a trial run consisting of two healthy subjects, and one transhumeral amputee implanted with the e-OPRA system. Although the subject group was not large enough to draw any statistical conclusions, the trial run and the results from it suggest that the methods could be used in a larger study to evaluate the cognitive workload of amputees implanted with the e-OPRA system.

Background: Recently there has been a revitalization in research on classic psychedelic substances. This class of drugs has been found to produce intense and profoundly meaningful experiences, and offers a unique opportunity to study the neural correlates of the sense of self. The objective of this research was to systematically review the effects of classic psychedelics on spontaneous brain activity, as measured on three electrophysiological modalities: spectral analysis, signal diversity, and functional connectivity. Method: We searched Pubmed to identify papers in English, published between January 1990 to May 2021, where electrophysiological methods were used to evaluate the effects of classic psychedelics in healthy individuals during non-task resting states. Results: Sixteen papers were included. Classic psychedelic substances generally decrease spectral power in most frequency bands, mainly in the alpha range, increase signal diversity, and decrease the flow of information throughout the brain. Conclusion: Decreases in alpha power, increased signal diversity, and decreases in default mode network activity might be important neural correlates of the psychedelic state. However, inconsistencies in the results and heterogeneity in study design are some of the limitations that have to be considered when interpreting these results.