Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographical references. / by Ilan Vardi. / Ph.D.

A crescente demanda do mercado mundial em aumentar a produção agrícola e minimizar danos ambientais confere crescente relevância à agricultura de precisão, para a qual a Geoinformação é uma importante ferramenta. Diferentes dados provenientes de imagem de sensores orbitais e terrestres têm sido utilizados para o monitoramento agrícola em escalas local, regional e global. Neste contexto, e focalizando esta percepção à viticultura, o objetivo deste estudo é avaliar o comportamento espectral de diferentes cultivares de videiras ao longo do ciclo fenológico, dando suporte para realização da discriminação espectral das variedades e o mapeamento da variação espacial do vigor vegetativo dentro da parcela. Para o desenvolvimento da pesquisa proposta o trabalho foi dividido em duas etapas. A primeira investigação consistiu em um estudo realizado em vinhedos da região de Borgonha na França, onde foram estudadas as variedades de uva Chardonnay e Pinot Noir. O trabalho teve como pressuposto verificar se as categorias de qualidade que definem os vinhedos e são transmitidas a partir do solo ao vinho são igualmente transmitidas às folhas das videiras, e se estas podem ser detectadas na informação espectral de imagens de satélites ASTER. Os resultados obtidos mostraram ser possível esta discriminação e instigaram novos estudos mais detalhados que foram conduzidos em vinhedos da Vinícola Geisse, localizada na Serra Gaúcha, realizados a partir de dados de radiometria de campo e imagens orbitais. Novamente foram investigadas as variedades viníferas Chardonnay e Pinot Noir, monitoradas ao longo de duas safras. As medições de campo foram realizadas com um radiômetro FieldSpec Pro. Também foram usados dados orbitais provenientes do sensor WorldView-2. Dados de campo e orbitais apresentaram relações consistentes, e mostraram ser possível discriminar as variedades através de suas características espectrais. A alta relação sinal/ruído dos dados de campo permitiu detectar diferenças consistentes e sistemáticas nos comprimentos de onda do verde e vermelho, atribuídas à presença de pigmentos como as antocianinas. O monitoramento da dinâmica espectral do ciclo fenológico revelou feições espectrais consistentes nos comprimentos de onda do infravermelho atribuídas ao período de senescência da videira. A espacialização dos dados de vigor vegetativo, obtidos através de índices de vegetação (NDVI) permitiu a setorização de áreas com diferentes potenciais enológicos. / The growing demand of world markets to increase agricultural production and to minimize environmental impacts puts the Geoinformation as an important tool of precision agriculture. Several sets of data of images from orbital and ground sensors have been used for agricultural monitoring at local, regional and global scales. In this context, focusing this perception to viticulture, the aim of this study was to evaluate the spectral comportment of different grapevine cultivars along of phenological cycle, giving support to realization of spectral discrimination of varieties and the mapping of the spatial variation of vegetative vigor within the plot. For the development of this project, our research was divided into two stages. The first research consisted in a study of vineyards of the Burgundy region in France, where the studied grape varieties were Chardonnay and Pinot Noir. The work was to verify the assumption that the quality categories that define the vineyards and are transmitted from the soil to wine are also transmitted to the leaves of the vines, and these can be detected in the spectral information contained in ASTER satellite images. Results showed that this discrimination is indeed possible, and lead to the second part of the project, with new and more detailed studies, which were performed in the vineyards of Geisse Winery, located in the Serra Gaúcha region, Brazil, based on field radiometry and orbital images. The same grape varieties Chardonnay and Pinot Noir grapes were again investigated. Field measurements were performed with a radiometer FieldSpec Pro. The investigation was made on two vine plots, based on a selection of plants of the Chardonnay and Pinot Noir, which were monitored over two growing seasons. Orbital data were from the WorldView-2 sensor. Field and orbital data showed consistent relations and showed that it is possible to distinguish the varieties by their spectral characteristics. The high relation signal/noise of field data allowed detecting consistent and systematic spectral features at red and green wavelengths, thought to be linked to the presence of pigments such as anthocyanins. The monitoring of spectral dynamics during the phenological cycle revealed consistent spectral features in infrared wavelengths assigned to the vine senescence period. The spatial distribution of vegetative vigor data obtained from the vegetation index (NDVI) allowed the sectorization of areas with different enological potentials.

Orientadores: Aldário Chrestani Bordonalli, Júlio César Rodrigues Fernandes de Oliveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-09-27T13:36:17Z (GMT). No. of bitstreams: 1 Carvalho_LuisHenriqueHeckerde_M.pdf: 8092940 bytes, checksum: da29699f8638d37de27fc0743c89a013 (MD5) Previous issue date: 2014 / Resumo: Uma das alternativas para os sistemas de transmissão óptica de próxima geração é o uso de múltiplos subcanais ópticos densamente multiplexados em frequência (supercanais) com alta eficiência espectral. Supercanais ópticos empregam o processamento paralelo de sinais para alcançar taxas de transmissão além dos limites da eletrônica. Atualmente, as técnicas CO-OFDM e Nyquist WDM são vistas como as principais para a implementação de supercanais ópticos. Neste trabalho, estudam-se abordagens para aumentar a capacidade de transmissão dos sistemas ópticos por meio da realização de supercanais. A implementação em laboratório, análise de desempenho e comparativo entre as técnicas CO-OFDM e Nyquist WDM são realizadas para sistemas operando a 400 Gb/s e 1 Tb/s por canal, com modulação DP-16QAM e eficiências espectrais que chegam a 6 b/s/Hz e acima. Os principais desafios e soluções para a implementação de sistemas de transmissão óptica de próxima geração baseados em supercanais são identificados / Abstract: One of the options for the next generation of optical transmission systems is the use of multiple optical subchannels densely multiplexed in frequency (superchannels) with high spectral efficiency. Optical superchannels employ parallel signal processing to achieve transmission rates beyond the limits of electronics. Currently, CO-OFDM and Nyquist WDM are seen as the main techniques to the implementation of optical superchannels. In this work, different ways to increase the capacity of the current optical systems by the realization of superchannels are studied. The experimental implementation, performance analysis, and comparison between CO-OFDM and Nyquist WDM techniques are performed for systems operating at 400 Gb/s and 1 Tb/s per-channel with DP-16QAM modulation and spectral efficiencies of 6 b/s/Hz and beyond. The main challenges and solutions for the implementation of next generation optical transmission systems based on superchannels are identified / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

A dinâmica em meso-escala nos oceanos globais é dominada por sinais propagantes para oeste. Estudos pioneiros a utilizar medidas de altimetria por satélites associaram este sinal a ondas de Rossby longas do primeiro modo baroclínico. Com o recente aumento de resolução nos dados altimétricos, estudos mais recentes sugerem que vórtices de meso-escala não-lineares seriam os principais responsáveis pelo sinal propagante observado, em detrimento às ondas de Rossby. O objetivo do presente trabalho é identificar estruturas coerentes associadas a vórtices de meso-escala e distingui-las das ondas de Rossby longas do primeiro modo baroclínico. Mapas de anomalia da altura da superfície do mar (η) foram filtrados através da análise de ondaletas e um algoritmo de identificação e extração de estruturas vorticais. Os vórtices extraídos foram caracterizados através do ajuste de um paraboloide elíptico. O algoritmo demonstrou-se capaz de identificar e extrair as estruturas associadas a vórtices de meso-escala. Os resultados indicam predominância de anéis vorticais anti-ciclônicos. Os espectros de potência zonais-temporais de η indicam que a maior parte da variância distribui-se na região não-dispersiva do espectro teórico de ondas de Rossby lineares. A propagação observada nos componentes resultantes do filtro indicam coexistência de ondas de Rossby lineares e vórtices de meso-escala, comprovando assim a hipótese científica estabelecida para este trabalho. / The mesoscale dynamics in the global oceans is dominated by westward propagating signals. Pioneering studies using satellite altimetry measurements associated these observations with first-mode baroclinic Rossby waves. With the increase in altimetry data resolution, recent studies suggest that nonlinear mesoscale eddies are responsible for the westward propagating signal rather than Rossby waves. The objective of this study is to identify coherent structures associated with mesoscale eddies and distinguish them from long first-mode baroclinic Rossby waves. Sea surface height anomaly maps (η) were filtered throught wavelet analysis and an algorithm for identifying and extracting vortical structures. The extracted vortices were characterized by adjusting an elliptic paraboloid. The algorithm proved to be able to identify and extract the structures associated to mesoscale eddies. The results indicate a predominance of anti-cyclonic rings. Zonal-temporal power spectral density of η indicate that most of the variance is located at the non-dispersive region of the theoretical linear Rossby wave spectra. The observed propagation of the filtered components indicate coexistence of linear Rossby waves and mesoscale eddies, thus proving the scientific hypothesis of this study.

As sequências espectrais foram criadas por Jean Leray num campo de concentração durante a Segunda Guerra Mundial motivado por problemas inerentes à Topologia Algébrica. Num primeiro momento, surge como uma ferramenta para auxiliar no cálculo da cohomologia de um feixe. Porém, Jean-Louis Koszul apresenta uma formulação puramente algébrica para tais sequencias, que consiste basicamente no cálculo da homologia de um complexo total associado a um complexo duplo. Concentraremos nosso trabalho nas definições e resultados que nos permitem demonstrar os seguintes resultados conhecidos da Álgebra usando sequências espectrais: o Lema dos Cinco, o Lema da Serpente, Balanceamento para o Funtor Tor, Mudança de Base para o Funtor Tor e o Teorema dos Coeficientes Universais. Apresentamos, ao final do trabalho, uma generalização que nos permite entender melhor os funtores derivados à esquerda: as Sequências Espectrais de Grothendieck. / Spectral sequences were created by Jean Leray in a concentration camp during World War II motivated by problems of Algebraic Topology. At first, it appears as a tool to assist in calculating the cohomology of a sheaf. However, Jean-Louis Koszul presents a purely algebraic formulation for these sequences, which basically consists in calculating a total of homology complex associated with a double complex. We will focus our work on the definitions and results that allow us to demonstrate known results of algebra using spectral sequences: The Five Lemma, The Snake Lemma, Balancing of functor Tor, Base Change for Tor and Universal Coefficient Theorem. We present, at the end of this work, a generalization that allows us to better understand the left derivative functors: the Spectral Sequence of Grothendieck.

There is a growing need for the clean generation of electricity in the world, and increased efficiency is one way to achieve cleaner generation. Increased efficiency may be achieved through an improved understanding of the heat flux of participating media in combustion environments. Real-time in-situ optical measurements of gas temperature and concentrations in combustion environments is needed. Optical methods do not disturb the flow characteristics and are not subject to the temperature limitation of current methods. Simpler, less-costly optical measurements than current methods would increase the ability to apply them in more circumstances. This work explores the ability to simultaneously measure gas temperature and H2O concentration via integrated spectral intensity ratios in regions where H2O is the dominant participating gas. This work considered combustion flows with and without fuel and soot particles, and is an extension of work previously performed by Ellis et al. [1]. Five different combustion regimes were used to investigate the robustness of the infrared intensity integral method first presented by Ellis et al. [1]. These included Post-Flame Natural Gas (PFNG), Post-Flame Medium Wood (PFMW), Post-Flame Fine Wood (PFFW), In-Flame Natural Gas (IFNG), and In-Flame Fine Wood (IFFW). Optical spectra were collected as a function of path length for each regime. Methods for processing the spectra to obtain gas temperature, gas concentration, broadband temperature, and broadband emissivity were developed. A one-dimensional spectral intensity model that allowed for specular reflection, and investigated differences between measured and modeled spectral intensities was created. It was concluded that excellent agreement (within 2.5%) was achieved between optical and suction pyrometer gas temperatures as long as 1) the optical probe and cold target used were well-aligned 2) the path length was greater than 0.3 m and 3) the intensity from broadband emitters within the path was smaller than the gas intensity. Shorter path lengths between 0.15 – 0.3 m produced reasonable temperatures with 7 % error while path lengths of 0.05 m or less were as much as 15% in error or the signal would not effectively process. Water vapor concentration was less accurate being at best within 20% (relative) of expected values. The accurate determination of concentration requires first an accurate temperature concentration as well low broadband participation. Some optical concentrations were in error as much as 85%. The 1-D model was compared to the measurement and it was found that the model peaks were sharper and shifted 0.167 cm-1 compared to the measured data. The reason for the shift can be attributed to the uncertainty of the reference laser frequency used in the FTIR. No conclusion was found for the cause of the sharper peaks in the model. The integrated area of bands used to find temperature and concentration matched well between the model and measured spectrum being typically within 3%.

The accuracy of modern digital human models has led to the development of human simulation engines capable of performing a complex analysis of the biometrics and kinematics / dynamics of a digital model. While the capabilities of these simulations have seen much progress in recent years, they are hindered by a fundamental limitation regarding the diversity of the models compatible with the simulation engine, which in turn results in a reduction in the scope of the applications available to the simulation. This is typically due to the necessary implementation of a musculoskeletal structure within the model, as well as the inherent mass and inertial data that accompany it. As a result a significant amount of time and expertise is required to make a digital human model compatible with the simulation. In this research I present a solution to this limitation by outlining a process to develop a set of mutually compatible human models that spans the range of feasible body shapes and allows for a “free” exploration of body shape within the shape manifold. Additionally, a method is presented to represent the human body shapes with a reduction of dimensionality, via a spectral shape descriptor, that enables a statistical analysis that is both more computationally efficient and anthropometrically accurate than traditional methods. This statistical analysis is then used to develop a set of representative models that succinctly represent the full scope of human body shapes across the population, with applications reaching beyond the research-oriented simulations into commercial human-centered product design and digital modeling.

The progress of science is based to a large degree on experimentation. The scientist, engineer, or researcher is usually interested in the results of a single experiment only to the extent that he hopes to generalize the results to a class of similar experiments associated with an underlying phenomenon. The process by which this is done is called inductive inference and is always subject to uncertainty. The science of statistical inference can be used to make inductive inferences for which the degree of uncertainty can be measure in terms of probability. A second type of inference called deductive inference is conclusive. If the premises are true, deductive inference leads to true conclusions. Proving the theorems of mathematics is an example of deductive inference; while in the empirical sciences, inductive inference is used to find new knowledge. In engineering and physical science, analytical , i.e., deterministic techniques have been developed to provide deductive descriptions of the real world. Sometimes the assumptions required to make deterministic techniques appropriate are too restrictive since no provision is made for stochastic or uncertainty involved in concluding real world situations. In these situations, the science of statistics provides a basis for generalizing the results of experiments associated with the phenomena of interest. In order to make statistical inference sound, the experimenter must decide in advance which factors must be controlled in the experiment. The factors which are unknown or which cannot be controlled must be controlled by the device of randomization. Uncontrolled factors express themselves as experimental error in the experiment. Randomization is used in order to insure that the experimental error satisfies the probability requirements specified in the statistical model for the experiment, thereby making it possible for the experimenter to generalize the results of his experiment using significance and confidence probability statements. Much of statistics is devoted to situations for which experiments are conducted according to schemes of restricted randomization. Therefore, the experimental errors are independent and are assumed to have a common, yet unknown, probability distribution that can be characterized by estimating the mean and the variance. However, there are certain other types of experimental situations for which it is desirable to observe a physical phenomena with the observations ordered in time or space. The resulting observations can be called a time series.The experimental errors of a time series are likely to be correlated. Consequently, if an unknown probability distribution is to be characterized, covariances as well as the respective means and the variances must be estimated. A time series resulting from observation of a given physical phenomena may exhibit dominant deterministic properties if the experiment can be well controlled. Or, the time series may exhibit dominant statistical properties if it is impossible or impractical to isolate and control various influencing factors. Generally an experiment will consist of both deterministic and statistical elements in some degree in a real world situation. The procedures of analysis presented in Chapter III consider the statistical analysis of periodic and aperiodic digital (discrete) time series, in both the time and frequency domains, using Fourier analysis, covariance and correlation analysis, and the estimation of power and cross power spectral density functions. Time ordered observations are important in the analysis of engineering systems. Certain characteristics of engineering systems are discussed in Chapter IV, and the input-output concept of control system engineering introduced. The input-output technique is not limited to control system engineering problems, but may be applicable in other areas of science also. A deterministic method of ascertaining the output performance of an engineering system consists of subjecting the system to a sinusoidal input function of time, and then measuring the output function of time. If the engineering system is linear, the well-developed techniques are available for analysis; but if the system is nonlinear, then more specialized analysis procedures must be developed for specific problems. In a broad sense, the frequency-response approach consists of investigating the output of a linear system to sinusoidal oscillations of the input. If the system of nonlinear, then the frequency-response approach must be modified; one such modification is the describing function technique. These techniques are also discussed in Chapter IV. Under actual experimental conditions, the deterministic approach of subjecting a system to a sinusoidal input function for purposes of analysis is likely to be complicated by nonlinearities of the system and statistical characteristics of the data. The physical characteristics of the data will undoubtedly be obscured by random measuring errors introduced by transducers and recording devices, and uncontrollable environmental and manufacturing influences. Consequently, generalized procedures for analyzing nonlinear systems in the presence of statistical variation are likely to be required to estimate the input-output characteristics if the system is to work with inferential models applied to recorded data. Such procedures are presented in Chapter III and Chapter V. In Chapter V the empirical determination from input-output rocket test data of a deterministic and statistical model for predicting rocket nozzle control system requirements is complicated by the fact that the control system is nonlinear and the nozzle data is non-stationary consisting of both systematic and random variation. The analysis techniques developed are general enough for analysis of other types of nonlinear systems. If the nonlinear effect of coulomb friction can be estimated and the responses are adjusted accordingly, the nozzle system bears a close relationship to a linear second order differential equation consisting of an acceleration times moment of enertia component, a gas dynamic spring component and a viscous friction component. In addition, vibration loading is present in the data. Consequently, estimation of auto correlation and power spectral density functions is used to isolate these vibrations. Analysis of the control system data is also considered in terms of auto correlations, and in terms of a power spectral density functions. Random input functions rather than sinusoidal input functions may be required under more general experimental conditions. Chapter VI numerically illustrates the analysis procedures. The actual rocket test data used in developing the analysis was classified; consequently, only fictitious data are used in this paper to illustrate the procedures. Chapter VIII is concerned with illustrating the procedures of Chapter III utilizing various time series data. The last part of Chapter VII is concerned with estimation of the power spectral function using techniques of multiple regression; i.e., the model of the General Linear Hypothesis. A definite limitation is the model assumption concerning the residual error of the model. The assumption concerning the error of the model can probably be made more tenable by suitable transformation of either the original time series data or the autocovariances. In any even the spectral function developed by assuming the model for the General Linear Hypothesis gives the same spectral function as defined in Chapter III. However, such quantities as the variance, tests of hypotheses and variance of the spectral function can now be estimated, if the assumptions concerning residual error are valid. Chapter VIII summarizes the results of previous chapters.

Highly repetitive motion is associated with upper extremity musculoskeletal disorders among industrial workers.Current methods of estimating occupational exposure to "repetitiveness" provide information about the repetitiveness of joint motion, but fail to provide complete information about the repetitiveness of muscular exertion, a more biomechanically meaningful measure of repetition. This thesis introduces an innovative digital signal processing method, from which muscular exertion frequency was estimated. Specifically, time series recordings of muscle activity obtained with surface electromyography (sEMG) were processed with standard root-mean-square (RMS) amplitude calculations and then transformed from the time domain into the frequency domain. The mean power frequencies of the RMS-processed sEMG signals (MPF EMG) were then calculated to estimate muscular exertion frequency. In a laboratory-based validation study involving repetitive isometric hand gripping exertions, MPF EMG was compared to measures of muscular exertion frequency and joint motion frequency across a range of known exertion frequencies, intensities, and durations. Strong linear relationships were observed between MPF EMG and external measures of muscular exertion frequency. However, performance of MPF EMG as a measure of muscular exertion frequency may be improved with an increase of the signal to noise ratio in the sEMG data. Signal processing parameters were therefore investigated. Alternative processing parameters were suggested to minimize difference between MPF EMG and established methods of muscular exertion frequency. A second laboratory-based validation study compared MPF EMG to a measure of muscular exertion frequency and a measure of joint movement frequency during a simulated industrial task. Although a stronger linear relationship was observed between metrics of joint motion frequency and established measures of muscular exertion, the differences between measures were not meaningful and the relationship between MPF EMG and established measures was moderate-to-strong. The final phase of this thesis explored the application of the proposed techniques to field-based data collected during a study of ironworkers involved in construction stud-welding tasks. Limitations in data collection limited the analysis of MPF EMG in this study. The research presented in this thesis introduces a novel metric based on the frequency analysis of RMS processed sEMG data, and presents evidence that MPF EMG has potential to be a valuable assessment technique of exposure to repetitive muscular exertion.

In a shallow aquifer underlain by low permeable material, groundwater recharge (R), discharge to rivers or stream as baseflow (BF), and discharge to the atmosphere as evapotranspiration (ET) are related by a simple water balance equation, R - ET - BF = ΔS. Gathering information about these processes is difficult since these processes are hidden from view, yet these processes commingle with one another at the water table surface. The main objective of this dissertation project was to evaluate how main hydrological processes can be inferred from high-resolution water table measurements collected at various sites in Walnut Creek watershed located in southern Iowa. Water table monitoring data available for analysis in the project included three main sites, covering 2573 days between 1996 to 2008 and 61,714 individual water level monitoring points. Water table fluctuations were used to estimate R across an upland-floodplain chronosequence and plant ET under three riparian land covers. High resolution hydraulic head measurements were analyzed with spectral methods to evaluate potential surface and groundwater interaction. Detailed sedimentology and water table monitoring were combined to develop a conceptual model of nitrate leaching to in the near-stream riparian zone of an incised channel. Additional soil moisture and precipitation monitoring are recommended for improved application of methods to other sites. Results from this dissertation indicate that there is a considerable amount of information about key hydrological processes to be gained by measuring water table levels at a high frequency.