O trabalho se estruturou em torno de dois estudos. O primeiro avaliou o ajuste de um modelo não linear de efeito misto para descrever o afilamento do tronco de árvores clonais de eucalipto. O modelo utilizado para descrever as variações da altura em função do raio foi o logístico de quatro parâmetros que, por integração permitiu a estimação do volume das árvores. A incorporação de funções de variância no processo de ajuste resultou em redução significativa no valor do Critério de informação de Akaike, mas os resíduos não apresentaram melhorias notáveis. Com a finalidade de compatibilizar precisão e parcimônia, o modelo que considera as variações do afilamento como uma função da altura total e do raio à altura do peito mostrou-se como o mais indicado para a estimativa do volume de árvores por funções de afilamento. O segundo estudo analisou uma nova proposta para inventários florestais em plantios clonais de eucalipto que integra modelagem geoestatística, medições de circunferência das árvores em campo e a tecnologia LiDAR aeroembarcada. As estatísticas propostas mostraram que o modelo geoestatístico com função para média foi estatisticamente superior ao modelo com média constante, com erros reduzidos em até 40%. A altura das árvores que compuseram o grid de predição para aplicação do modelo geoestatístico foi obtida pelo processamento da nuvem de pontos dos dados LiDAR. Obtidos os pares de diâmetro e altura, aplicou-se o modelo de afilamento selecionado no primeiro artigo em que se observaram diferenças médias na predição do volume próximas a 0,7%, e 0,18% para contagem de árvores, ambas com tendências de subestimativas. Diante dos resultados obtidos, o método é considerado como promissor e trabalhos futuros visam gerar um banco de parcelas permanentes que propiciem estudos de crescimento e produção florestal. / This study investigates the use of mixed-effect model and the use of LiDAR based model to estimate volume from eucalyptus forest plantation. At the first part, this study evaluates nonlinear mixed-effects to model stem taper of monoclonal Eucalyptus trees. The relation between radius and height variation was described by the four-parameter logistic model that integration returns stem volume. Embedding variance functions to the estimation process decreased significantly the Akaike\'s Information Criterion but did not improve the residual analysis. The best model to estimate stem volume from taper equations explained the stem taper as a function of the commercial height and the radius at breast height. The second part investigated the volume estimation fusing geostatistic derived from field information and airborne laser scanning data. The model based on geostatistic assumptions was statistically superior to the traditional one, with errors 40% lower. Thus, the geostatistical model was applied over tree heights extracted from the laser cloud. To each combination of diameter and height, the taper equation form the first part of this study was used. The volume and the number of trees were underestimated in 0.7% and 0.18%, respectively. The results look promising, and more permanent plots are necessary to allow studies about growth and yield of forest.

"A well-known challenge in estimating the distance of the antenna pair in time-of-arrival (ToA) based RF localization systems is the problem of obstruction of the direct path (DP) between transmitter and receiver. The absence of DP component in received channel profile creates undetected direct path (UDP) conditions. UDP condition, in turn, will cause occurrence of unexpected large ranging errors which pose serious challenge to precise indoor localization. Analysis of the behavior of the ranging error in such conditions is essential for the design of precise ToA-based indoor localization systems. This dissertation discusses two open problems in ToA-based indoor localization systems. The first contribution of this dissertation discusses the problem of modeling of dynamic behavior of ranging error. We propose a novel analytical framework for analysis of dynamic spatial variations of ranging error observed by a mobile user based on an application of Markov chain. The model relegates the behavior of ranging error into four main categories associated with four states of Markov process. Parameters of distributions of ranging error in each Markov state are extracted from empirical data collected from a measurement-calibrated ray tracing algorithm simulating a typical office environment. The analytical derivation of parameters of the Markov model employs the existing path-loss models for first detected path and total multipath received power in the same office environment. Results of simulated errors from the Markov model and actual errors from empirical data show close agreement. The second contribution of this dissertation discusses the problem of identification of UDP condition given an unknown channel profile. Existing of UDP condition in a channel profile poses serious degradation to ranging estimate process. Therefore, identification of occurrence of UDP condition is of our subsequent concern. After identification, the second step is to mitigate ranging errors in such conditions. In this dissertation we present two methodologies, based on binary hypothesis testing and an application of artificial neural network design, to identify UDP conditions and mitigate ranging error using statistics extracted from wideband frequency-domain indoor measurements conducted in typical office building. "

Submitted by William Justo Figueiro (williamjf) on 2015-07-01T23:37:49Z No. of bitstreams: 1 10.pdf: 1839460 bytes, checksum: 72eb68f5839e6788cf3f08b69ca3d26c (MD5) / Made available in DSpace on 2015-07-01T23:37:49Z (GMT). No. of bitstreams: 1 10.pdf: 1839460 bytes, checksum: 72eb68f5839e6788cf3f08b69ca3d26c (MD5) Previous issue date: 2011 / FAPERGS - Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul / O sistema LIDAR obtém nuvens de pontos georreferenciadas que podem ser convertidas em Modelos Digitais de Afloramentos (MDAs). Os pulsos de laser são gerados e emitidos por um Laser Scanner Terrestre, que atinge a superfície do afloramento em diferentes pontos. Estes objetos refletem o pulso incidente, que volta para o equipamento. Com isso, a distância entre o sensor e o objeto é determinada com base no intervalo de tempo entre a emissão e o retorno do pulso. Para fins de Modelagem Digital de Afloramentos (MDA) o uso dessa técnica é recente e necessita do desenvolvimento de pesquisas. Diante disso, o objetivo desse trabalho foi estabelecer uma sequencia de métodos envolvendo a aquisição e processamento de nuvem de pontos e a visualização e interpretação de superfícies e volumes de um Modelo Digital de Afloramentos (MDA). A Rocha da Pedra Pintada, localizado no Rio Grande do Sul na Cidade de Caçapava do Sul, foi imageado a partir de 7 estações e a nuvem totalizou 17 milhões de pontos, que foi convertida, após processamento, em um MDA. Para a interpretação geológica, utilizou-se a técnica de ortorretificação para sobrepor a nuvem de pontos a fotografias de alta resolução do afloramento, o que agregou qualidade na visualização e interpretação do MDA. Dificuldades nas etapas de tratamento dos dados ocorreram em razão do grande volume de dados, da ausência de recursos de otimização de processamento e da limitação no gerenciamento de banco de dados. Além disso, faz-se necessário desenvolver um aplicativo eficiente de visualização tridimensional com ferramentas especificas de interpretação geológica. / The LIDAR system provides georeferrenced clouds with thousand-to-million of points which can be converted in digital outcrops models. A laser beam is emitted and captured by a laser scanner after reaching an outcrop in many different positions. Based on the travel time between sensor and outcrop it is possible to determine the position of each point with high accuracy. This technique is still a novelty for applied studies in Geology, especially in Digital Outcrop Models (DOMs), being necessary research and development. Thus, the goal of this work was establish a workflow concerning acquisition and processing of point clouds, and visualization and geological interpretation of DOMs. The Pedra Pintada, located in the state Rio Grande do Sul in the city Caçapava do Sul outcrop was imaged from seven different stations and the cloud has 17 million points, converted in a DOM after processing. The geological interpretation was made possible by the orthorectification technique, in which a high resolution photograph overlies the point cloud and the visual quality is obtained. The huge volume of data, the lack of optimized processing resources and the inadequate dataset management became visualization and interpretation of DOMs a difficult task. Furthermore, it is necessary to develop a software with an efficient tridimensional visualization system with specific tools for geological interpretations.

Plus de 70 % de la surface terrestre est recouverte par les mers et océans. Nombre de phénomènes tectoniques parmi les plus dévastateurs ont par ailleurs lieu en environnement océanique. On peut citer en exemple les zones de subduction, pouvant générer des mégaséismes associés à des tsunamis dévastateurs (Sumatra en 2004, Tohokuen 2011), mais aussi les failles décrochantes sous-marines. Dans de nombreux cas, les méthodes de géodésie spatiale ne permettent pas de discriminer entre un comportement bloqué ou asismique, les instruments étant situés trop loin de la zone potentiellement déformée par le processus tectonique. Il faut alors mettre au point de nouvelles techniques qui permettent de prolonger les réseaux d’observation classiques au large afin de cartographier la déformation sur l’intégralité de la zone. Cette thèse s’intéresse à deux méthodes de géodésie fond de mer permettant d’aider à l’évaluation du risque sismique. La première est la distancemétrie relative acoustique, avec comme zone d’application effective la mer de Marmara. Nos premiers résultats laissent supposer un comportement bloqué au niveau du segment de la faille nord-anatolienne immergé devant İstanbul. La seconde zone d’étude considérée est la subduction antillaise. L’échelle de travail nécessite une localisation des points observés dans un référentiel global. Nous étudions les phénomènes océaniques à considérer et détaillons une méthodologie dite GNSS/A (pour Acoustique), consistant en des interrogations acoustiques depuis une plateforme de surface précisément positionnée par GNSS, pour une future expérience de positionnement absolu au large de la Guadeloupe. / More than 70 % of the Earth surface is covered by seas and oceans. Several tectonic phenomena, among the most devastating, take place in ocean environment. For example, the subduction zones, which can generate mega-earthquakes associated with devastating tsunamis (Sumatra in 2004, Tōhoku in 2011), but also the underwater strike-slip faults. In many cases, methods of space geodesy cannot discriminate between a blocked or aseismic behavior, because the instruments are located too far from the area potentially deformed by the tectonic process. Thus, it is necessary to develop new techniques to extend conventional observation networks off-shore to map the deformation in the entire area. This thesis focuses on two seafloor geodesy methods, in order to assess the seismic risk evaluation. The first is the relative acoustic ranging, with an efective deployment of the Marmara Sea area. Our early results suggest a locked state at the segment of the North Anatolian fault of İstanbul. The second area considered is the Caribbean subduction. The working scale requires localization of the observed points in a global reference frame. We study ocean processes to consider, and detail a GNSS/A (Acoustic) methodology, consisting of acoustic interrogations from a precisely GNSS positioned surface platform, for a future absolute positioning experience of Guadeloupe.

Dans le cadre de cette thèse, on se proposait de développer de nouveaux mécanismes de radiolocalisation, permettant de positionner les nœuds de réseaux corporels sans-fil (WBAN) mobiles, en exploitant de manière opportuniste des liens radio coopératifs bas débit à l'échelle d'un même corps (i.e. coopération intra-WBAN), entre réseaux distincts (i.e. coopération inter-WBAN), et/ou vis-à-vis de l'infrastructure environnante. Ces nouvelles fonctions coopératives présentent un intérêt pour des applications telles que la navigation de groupe ou la capture de mouvement à large échelle. Ce sujet d'étude, par essence multidisciplinaire, a permis d'aborder des questions de recherche variées, humine-biomécanique et de ayant trait à la modélisation physique (e.g. modélisation spatio-temporelle des métriques de radiolocalisation en situation de mobilité, modélisation de la mobilité groupe...), au développement d'algorithmes adaptés aux observables disponibles (e.g. algorithmes de positionnement coopératifs et distribués, sélection et ordonnancement des liens/mesures entre les nœuds...), aux mécanismes d'accès et de mise en réseau (i.e. en support aux mesures coopératives et au positionnement itératif). Les bénéfices et les limites de certaines de ces fonctions ont été en partie éprouvés expérimentalement, au moyen de plateformes radio réelles. Les différents développements réalisés tenaient compte, autant que possible, des contraintes liées aux standards de communication WBAN émergeants (e.g. Impulse Radio - Ultra Wideband (IR-UWB) IEEE 802.15.6), par exemple en termes de bande fréquentielle ou de taux d'erreur. / The PhD investigations aim at exploring new WBAN cooperative localization mechanisms, which could benefit jointly from on-body links, body-to-body links between distinct mobile users or off-body links with respect to the infrastructure. Following a multidisciplinary approach, we have thus addressed theoretical questions related to physical modeling or to algorithmic and cross-layer design. A few more practical aspects have also been dealt with. More specifically, based on WBAN channel measurements, single-link ranging error models are first discussed for more realistic performance assessment. Then a Constrained Distributed Weighted Multi-Dimensional Scaling (CDWMDS) positioning algorithm is put forward for relative MoCap purposes, coping with on-body nodes' asynchronism to reduce system latency and exploiting the presence of constant-length radio links for better accuracy. Subsequently we consider extending this algorithm for larger-scale asbolute MoCap applications within a 2-step localization approach that incorporates additional off-body links in a heterogeneous WBAN framework. Then, both individual and collective kinds of navigation are addressed. In both MoCap and navigation scenarios, low-complexity solutions exploiting on-body deployment diversity enable to combat error propagation and strong range biases due to body shadowing, relying on on-body nodes' dispersion or graph neighborhood to approximate the corrupted distances. Finally, experiments based on real IR-UWB radio platforms validate in part the previous proposals, while showing their practical limitations.

In this study, accurate target tracking for bearings-only tracking problem is investigated. A new tracking filter for this nonlinear problem is designed where both range parameterization and Rao-Blackwellized (marginalized) particle filtering techniques are used in a Gaussian mixture formulation to track both constant velocity and maneuvering targets. The idea of using target turn rate in the state equation in such a way that marginalization is possible is elaborated. Addition to nonlinear nature, unobservability is a major problem of bearings-only tracking. Observer trajectory generation to increase the observability of the bearings-only tracking problem is studied. Novel formulation of observability measures based on mutual information between the state and the measurement sequences are derived for the problem. These measures are used as objective functions to improve observability. Based on the results obtained better understanding of the required observer trajectory for accurate bearings-only target tracking is developed.

This paper attempts to use image processing methods to reduce the influences of ambient light and scattering effect on the performance of an underwater range finder. The Taguchi method, as well, is employed to increase the repeatability of underwater range finding. In this study, the image processing methods of the least-squares approximation, brightness and contrast adjustment, and primary color processing are presented. The illumination center is also used to estimate the position of the laser spot in the image. In addition, a bandpass optical filter at the receiving end is used to investigate the effects of filters on the quality of range finding. To verify the effectiveness of the proposed image processing methods, a series of DOE process runs are carried out to study effects of the design parameters on quality of range finding. For each image processing method, its corresponding control factors and levels are assigned to an inner orthogonal array. To make the proposed image processing methods robust against noises, both environmental illumination and turbidity are forced into the experiments by utilizing an outer orthogonal array. Images for processing are then captured under different noise conditions in accordance with the allocation of the outer noise array. And, according to the layout of the inner array, the S/N ratio of each treatment combination is calculated. After that, the optimum combination of control factors is predicted through the analysis of variance. Then, the confirmation experiments are carried out to verify that the combination of control factors at the perceived best levels is valid. Based on the results of experiments and analyses, it is found that the least-squares approximation is better than other proposed image processing methods for increasing the quality of range finding. Moreover, the effect of increasing quality of range finding by using the least-squares approximation is superior to that of using a bandpass optical filter. Even though a range finding system has incorporated a bandpass optical filter for filtering out unwanted noises, the quality of range finding can still be increased distinctly while the algorithm of the least-squares approximation is employed. As well, the least-squares approximation is feasible to reduce the scattering effects in the laser images if the size of the sparse backscattering light spot is smaller than that of the target light spot.

Passive wireless sensor networks (WSNs) are quickly becoming popular for many applications such as article tracking, position location, temperature sensing, and passive data storage. Passive tags and sensors are unique in that they collect their electrical energy by harvesting it from the ambient environment. Tags with charge pumps collect their energy from the signal they receive from the transmitting source. The efficiency of converting the received signal to DC power is greatly enhanced using a power-optimized waveform (POW). Measurements in the first part of this dissertation show that a POW can provide efficiency gains of up to 12 dB compared to a sine-wave input. Tracking the real-time location of these passive tags is a specialized feature used in some applications such as animal tracking. A passive WSN that uses POWs for the improvement of energy-harvesting may also estimate the range to a tag by measuring the time delay of propagation from the transmitter to the tag and back to the transmitter. The maximum-likelihood (ML) estimator is used for estimating this time delay, which simplifies to taking the cross-correlation of the received signal with the transmitted signal. This research characterizes key aspects of performing range estimations in passive WSNs using POWs. The shape of the POW has a directly-measurable effect on ranging performance. Measurements and simulations show that the RMS bandwidth of the waveform has an inversely proportional relationship to the uncertainty of a range measurement. The clutter of an environment greatly affects the uncertainty and bias exhibited by a range estimator. Random frequency-selective environments with heavy clutter are shown to produce estimation uncertainties more than 20 dB higher than the theoretical lower bound. Estimation in random frequency-flat environments is well-behaved and fits the theory quite nicely. Nonlinear circuits such as the charge pump distort the POW during reflection, which biases the range estimations. This research derives an empirical model for predicting the estimation bias for Dickson charge pumps and verifies it with simulations and measurements.

The use of Light Detection and Ranging (LiDAR) information is gaining popularity, however its use has been limited in deciduous forests. This thesis describes two studies using LiDAR data in an Eastern Kentucky deciduous forest. The first study quantifies vertical error of LiDAR derived digital elevation models (DEMs) which describe the forests terrain. The study uses a new method which eliminates Global Positioning System (GPS) error. The study found that slope and slope variability both significantly affect DEM error and should be taken in to account when using LiDAR derived DEMs. The second study uses LiDAR derived forest vegetation and terrain metrics to predict terrestrial Plethodontid salamander abundance across the forest. This study used night time visual encounter surveys coupled with zero-inflation modeling to predict salamander abundance based on environmental covariates. We focused on two salamander species, Plethodon glutinosus and Plethodon kentucki. Our methods produced two different best fit models for the two species. Plethodon glutinosus included vegetation height standard deviation and water flow accumulation covariates, while Plethodon kentucki included only canopy cover as a covariate. These methods are applicable to many different species and can be very useful for focusing management efforts and understanding species distributions across the landscape.

Diseases that infect wildlife populations pose a significant threat to public health, agriculture, and conservation efforts. The spread of these diseases can be influenced by the social structure of the population, and therefore often need to be accounted for in disease models. In this thesis I use high-resolution contact data to explore the social structure of a high-density population of European badgers (Meles meles). I explore how this structure might influence the spread of bovine tuberculosis (bTB), a debilitating disease of cattle for which badgers are a wildlife reservoir. Denning and home range data collected using radio tracking is also used to determine how this social structure is related to badger space use. I use social network analysis to identify the community structure of the badger population, revealing that badgers interact in fewer, more distinct groups than previously assumed. This is likely to inhibit the spread of disease through the population, given that the probability of infection entering a new social group will be reduced. However, among-group contact is still found to occur even between the most isolated groups. I show that this among-group contact is more likely to occur between less related individuals, possibly suggesting that breeding behaviour may drive among-group contact as a mechanism for inbreeding avoidance. To gain additional insight into this among-group contact, I determine how badger spatial behaviours are related. I show that the use of dens (setts) away from the social group’s main sett (outlier setts) in the spring is associated with extra-territorial ranging. I also show that this extra-territorial ranging is associated with more central network positions. The seasonality of this behaviour further suggests that this may be related to breeding activity. These findings suggest that behaviours associated with extra-group ranging may increase the risk of acquiring and transmitting infection. Therefore, use of outlier setts in the spring could act as a spatial proxy to identify high-risk individuals for disease spread, offering potential targets for disease control. Finally, I discuss the implications of these findings in regard to what they reveal about badger behaviour, disease transmission, and the design of effective disease control strategies. The importance of understanding population social structure for the study of wildlife disease in general is also discussed.