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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Diversidade e Padrões de Distribuição de Mamíferos dos Pampas do Uruguai e Brasil / Diversity and distributional patterns of pampean mammals of Uruguay and Brazil

Diego Queirolo Morató 02 July 2009 (has links)
Pela primeira vez considerou-se a fauna de mamíferos dos Pampas do sul do Brasil e do Uruguai como um todo, independentemente de fronteiras políticas. Primeiramente, foi obtida informação sobre ocorrência das espécies na área de estudo a partir de diferentes fontes e logo se elaboraram mapas de distribuição para todas elas. Na seqüência, tratou-se de determinar por meio de análises quantitativas o padrão de distribuição geográfica das mesmas realizando, primeiramente, uma análise entre sub-regiões (UGOs) dentro da área de estudo, para logo compará-la com regiões vizinhas e, por último, com ambientes similares distribuídos em outros continentes. Também, analisou-se preliminarmente o estado de conservação das espécies de mamíferos que ocorrem dentro da área de estudo. Foi obtida informação de coleções científicas (2.080 registros), de literatura (439 registros de resumos de reuniões científicas e 868 de revistas periódicas, livros, dissertações, teses e relatórios), 63 de observação ou comunicação pessoal de diferentes pesquisadores e o restante de outras fontes. No total, consideraram-se 3.522 registros (1.738 no Uruguai e 1.784 Brasil) distribuídos em 1.041 localidades. Foram identificadas 125 espécies (80 para o Uruguai e 117 para o Rio Grande do Sul), sete delas são endêmicas e seis são consideradas como extintas. Os roedores junto aos quirópteros e marsupiais somam 68,6% dos gêneros e os dois primeiros também ultrapassam 60% do total de espécies. As maiores riquezas foram encontradas naquelas áreas mais estudadas. A análise de agrupamento das UGOs mostrou dois grupos bem definidos, um conformado pelo Uruguai e pela região da Campanha Gaúcha e o outro, pelo litoral Atlântico, leste e centro do Rio Grande do Sul. Em relação às regiões vizinhas, observou-se claramente um grupo formado pelas Províncias florestais, onde está incluída a área de estudo. Na análise das ecoregiões o grupo conformado por aquelas de origem tropical e/ou florestal também foi o que incluiu a área de estudo. Existiram diferenças significativas nos hábitos de locomoção e marginalmente significativas nos hábitos alimentares em comparação com as regiões vizinhas. No entanto, na comparação dos hábitos alimentares com outros ambientes similares de campos temperados distribuídos em outros continentes, sim houve diferença significativa indicando pouca semelhança entre a estrutura das comunidades. Por último, 31 espécies foram consideradas ameaçadas nos Pampas do Rio Grande do Sul e 21 no Uruguai, resultando num total de 47 para toda a região (37,6% do total). Este trabalho pretendeu colaborar com a geração de informação básica fundamental para a formulação de políticas de conservação que contemplem toda a região independentemente dos países que a compõem. / For the first time the mammalian fauna of the Pampas from Uruguay and southern Brazil was considered as a whole, despite political borders. Information on species distribution in the study area was obtained from different sources and a distribution map was elaborated for each species. After that we identified the pattern of geographical distribution of mammals in the region by using quantitative analysis. First of all, we analyzed the sub-regions (OGUs) inside the study area, after that we compared those OGUs with neighbour areas, and finally with similar environments around the world. We also did a preliminary analysis of the conservation status of the species registered. Information was obtained from scientific collections (2,080 records), from literature (439 from scientific reunion abstracts; 868 from manuscripts, books, thesis and other kind of bibliography), 63 from personal communications or observations, and the rest from other sources. In general, 3,522 registers were considered (1,738 in the Uruguay and 1,784 in the Brazil), totaling 1,041 different localities. One hundred twenty five species were identified (80 from Uruguay and 117 from Rio Grande do Sul), being seven of them endemic species and six extinct species at the moment. The rodents together with the bats and the marsupials conform 68.6% of the genera found. Also, the two former exceed 60% of the total number of species. Largest richness was found in most studied areas. Cluster analysis showed two welldefined groups of OGUs: 1. Uruguay and Campanha Gaucha region and 2. Atlantic coast, East and Center of Rio Grande do Sul State. Concerning the neighbour areas we observed a group structured by the forestal Provinces in which the study area was included. The Ecoregions analysis showed three groups, and the one composed by forestal and/or tropical regions also integrate the study area. There were significant differences related to locomotor habits when comparing the structure of community with neighbour regions and marginally significant differences concerning diet. However, when comparing the diet with similar environments of temperate grasslands in other continents there were significant difference, which means little similitude between the mammalian communities. Finally, we identified 31 species with some degree of threat in the Pampas from Rio Grande do Sul and 21 from Uruguay, with 47 threatened species in the region (37,5% of the total). This work intended to collaborate with essential information in order to elaborate conservation politics that consider the entire region, independent of the countries which compose it.
222

Contribuições à modelagem de teletráfego fractal. / Contribution to the modeling of fractal teletrffic

Alexandre Barbosa de Lima 28 February 2008 (has links)
Estudos empíricos [1],[2] demonstraram que o trafego das redes Internet Protocol (IP) possui propriedades fractais tais como impulsividade, auto-similaridade e dependência de longa duração em diversas escalas de agregação temporal, na faixa de milissegundos a minutos. Essas características tem motivado o desenvolvimento de novos modelos fractais de teletráfego e de novos algoritmos de controle de trafego em redes convergentes. Este trabalho propõe um novo modelo de trafego no espaço de estados baseado numa aproximação finito-dimensional do processo AutoRegressive Fractionally Integrated Moving Average (ARFIMA). A modelagem por meio de processos auto-regressivos (AR) também é investigada. A analise estatística de series simuladas e de series reais de trafego mostra que a aplicação de modelos AR de ordem alta em esquemas de previsão de teletráfego é fortemente prejudicada pelo problema da identificação da ordem do modelo. Também demonstra-se que a modelagem da memória longa pode ser obtida as custas do posicionamento de um ou mais pólos nas proximidades do circulo de raio unitário. Portanto, a implementação do modelo AR ajustado pode ser instável devido a efeitos de quantização dos coeficientes do filtro digital. O modelo de memória longa proposto oferece as seguintes vantagens: a) possibilidade de implementação pratica, pois não requer memória infinita, b) modelagem (explícita) da região das baixas freqüências do espectro e c) viabilização da utilização do filtro de Kalman. O estudo de caso apresentado demonstra que é possível aplicar o modelo de memória longa proposto em trechos estacionários de sinais de teletráfego fractal. Os resultados obtidos mostram que a dinâmica do parâmetro de Hurst de sinais de teletráfego pode ser bastante lenta na pratica. Sendo assim, o novo modelo proposto é adequado para esquemas de previsão de trafego, tais como Controle de Admissão de Conexões (CAC) e alocação dinâmica de banda, dado que o parâmetro de Hurst pode ser estimado em tempo real por meio da aplicação da transformada wavelet discreta (Discrete Wavelet Transform (DWT)). / Empirical studies [1],[2] demonstrated that heterogeneous IP traffic has fractal properties such as impulsiveness, self-similarity, and long-range dependence over several time scales, from miliseconds to minutes. These features have motivated the development of new traffic models and traffic control algorithms. This work presents a new state-space model for teletraffic which is based on a finite-dimensional representation of the ARFIMA random process. The modeling via AutoRegressive (AR) processes is also investigated. The statistical analysis of simulated time series and real traffic traces show that the application of high-order AR models in schemes of teletraffic prediction can be highly impaired by the model identification problem. It is also demonstrated that the modeling of the long memory can be obtained at the cost of positioning one or more poles near the unit circle. Therefore, the implementation of the adjusted AR model can be unstable due to the quantization of the digital filter coefficients. The proposed long memory model has the following advantages: a) possibility of practical implementation, inasmuch it does not require infinite memory, b) explicit modeling of the low frequency region of the power spectrum, and c) forecasts can be performed via the Kalman predictor. The presented case study suggests one can apply the proposed model in periods where stationarity can be safely assumed. The results indicate that the dynamics of the Hurst parameter can be very slow in practice. Hence, the new proposed model is suitable for teletraffic prediction schemes, such as CAC and dynamic bandwidth allocation, given that the Hurst parameter can be estimated on-line via DWT.
223

Representação de estruturas sujeitas à cargas de impacto através de modelos escalonados: estrutura e modelo feitos de materiais diferentes. / Representing structures subjected to impact loads with scaled models: structure and model made of different materials.

Leonardo Monteiro Mazzariol 03 February 2017 (has links)
Lança-se aqui a hipótese de que é possível reproduzir o comportamento do protótipo a partir de modelos feitos de materiais diferentes dos utilizados na estrutura de referência. A influência de distorção de espessura, de diferentes densidades, tensões de escoamento, encruamento e viscoplasticidade são todas avaliadas através de equações analíticas e simulações das estruturas básicas como viga, placa e o impacto de uma estrutura de chapa dupla. Adicionalmente, são realizadas caracterizações quase-estáticas e dinâmicas de material e experimentos em placas circulares para três escalas diferentes (1/1, 2/3 e 1/3), quatro materiais (alumínio, titânio, aço inox e cobre) e duas condições de carregamento: impacto de uma massa a baixa velocidade (3,5m/s) e um projétil a alta velocidade (130m/s). Mostra-se que o uso da lei de Johnson-Cook para descrever o comportamento viscoplástico dos materiais permite obter boa aproximação para o cálculo da velocidade de impacto corrigida, sem que sejam necessárias informações adicionais do comportamento da estrutura. Além disso, os resultados revelam a importância de se manter a razão entre massa de impacto e massa da estrutura constante em modelo e protótipo, levando a desejável similaridade das distorções entre ambas. Assim, ao se confirmar a hipótese deste trabalho, mostra-se possível inferir o comportamento de um protótipo com uso de modelos em escala reduzida feitos a partir de materiais diferentes. / It is hypothesized that it is possible to reproduce the behaviour of the prototype by using models made of different materials. The influence of thickness, different densities, flow stresses, hardening and viscoplasticity are all evaluated through analytical equations and simulations of basic structures such as beam, plate and the impact of a double plate structure. In addition, quasi-static and dynamic materials characterization are conducted , with experiments being performed in circular plates for three different scales (1/1, 2/3 and 1/3), four materials (Aluminum, Titanium, Stainless Steel and Copper) and two conditions impact of a mass (3,5m/s) and a projectile at high speed (130m/s). It is shown that the use of Johnson-Cook\'s law to describe the viscoplastic behavior of the materials allows a satisfactory approximation to the calculation of the corrected impact velocity, without the need for additional information on the behavior of the structure. In addition, the results reveal the relevance of maintaining the ratio between impact mass and structure mass constant in model and prototype, leading to the desirable similarity of the distortions between the two. Thus, when confirming the hypothesis of this work, it is possible to infer the behavior of a prototype using small scale models made from different materials.
224

Estudo da similaridade imperfeita em estruturas sujeitas a carregamentos de impacto. / Study of imperfect similarity in structures subjected to impact loadings.

Roberto Eiki Oshiro 09 June 2010 (has links)
As leis usuais de redução de escala não produzem bons resultados em estruturas sujeitas a cargas de impacto, gerando uma semelhança imperfeita entre modelo e protótipo. Neste trabalho, utiliza-se a técnica de similaridade não direta através da alteração da velocidade inicial do corpo de impacto, gerando uma resposta do modelo idêntica ao do protótipo. Três fatores que contribuem para a resposta não similar da estrutura em escala são estudados nessa tese: taxa de deformação e modelo com parâmetros geométricos e de material distorcidos em relação ao protótipo. Além disso, mostra-se como a técnica proposta pode ser usada para correção das distorções através da mudança da massa de impacto. Considerando-se todos esses elementos, um procedimento abrangente e simples que gera um modelo com comportamento similar ao do protótipo é criado. Para corroborar as hipóteses levantadas durante a tese e estudar o método de correção, três problemas analíticos e dois problemas numéricos são explorados. Em todas as análises, os resultados mostram uma melhora significativa na semelhança entre modelo e protótipo após a aplicação do método de correção apresentado. Ao longo do trabalho, as vantagens e limitações das técnicas desenvolvidas e as principais diferenças em relação a trabalhos anteriores são detidamente discutidas. / Current scaling laws are not capable of predicting the structural impact response of prototypes from the behavior of the corresponding scaled models. Here, the nondirect similitude technique is employed by changing the initial impact velocity loading so that model and prototype behave the same. Three main factors that contribute to the non-similar response of a scaled structure are investigated: strain rate, model geometry and material parameters distorted in relation to the prototype. Moreover, it is shown how the proposed technique can be applied to alter the impact mass instead of its velocity. By considering all these aspects, it is then created a comprehensive and simple procedure that generates models similar to a given prototype. Three analytical and two numerical problems are used to present the main features of the technique. In all the cases analyzed, after the correction is applied, it was possible to accurately predict the behavior of the structure under analysis by the response of the model. Throughout this work, limitations and advantages of the method are emphasized bearing in mind other published works.
225

I'd Give My Right Kidney to Be Altruistic: The Social Biogeography of Altruism in the United States of America

Garcia, Rafael Antonio, Garcia, Rafael Antonio January 2017 (has links)
The purpose of this dissertation is to model biosocial determinants of group-directed altruistic behavior – exploring the nomological net around it. To do this a study will be presented to determine existing associations among various biological and social predictors and test a life-history-derived causal cascade using a partially exploratory and partially confirmatory statistical technique called Sequential Canonical Analysis to ultimately predict living-donor, non-directed kidney donations (NDKD). Toward that end, some important methodological considerations first need to be discussed. The first consideration revolves around the level of analysis and how this frames the cascade model and its interpretation. Following a general discussion, an exercise in some of the general principles is provided – investigating the higher-order factor structure of the Big-5 personality constructs across two levels of analysis. The second consideration is the use of unit-weighted factor scores and their appropriateness. Following the theoretical discussion, a demonstration is provided – deriving an estimate of genetic relatedness from a set of heterogeneous data sets. Once the methodological considerations have been discussed, the primary cascade model is presented in two parts: 1) the measurement model – operationalizing the measures incorporated into 2) the structural model – testing the proposed causal cascade using Sequential Canonical Analysis. A discussion follows in which the results are summarized, limitations are articulated, and further research directions are explored.
226

Religious and Ritualized Landscapes of Iron Age North Central Eurasia

MacFarland, Kathryn Anne, MacFarland, Kathryn Anne January 2017 (has links)
Animal Style Art (ASA), an iconographic style expressed on monuments and material culture, is a geographically widespread phenomenon in north central Eurasia during the Iron Age (ca. 1,000 BCE – 100 CE). Frequently depicted elements of this style include composite animals composed of animal elements fused together to create a new mythical animal; a stylized geometric design within the animal; and an interaction of some kind (e.g., one figure attacking another, figures standing nearby, single animal). The research presented in this dissertation focuses on the possibility that ASA constitutes evidence for a pan-regional religion in north central Eurasia during the Iron Age. Systematic study of ancient texts, ethnography, archaeological remains, and a detailed stylistic analysis of the complex elements of ASA, have all contributed to this research. This analysis is an artifact-focused macro-scale (continental) study of ASA, breaking down the cultural contexts as well as the geographical and chronological distribution in which it occurs, and the elements of the style itself, analyzing patterns of occurrence and similarity throughout north central Eurasia. This has been accomplished by the creation of a database, specifically designed as a museum curation tool and as a Geographic Information System (GIS) resulting in a dataset of 4,633 catalog lots (a single object or set). These data contribute to the identification of internal patterns in the expression of this iconographic style between regions of north central Eurasia and is inferred as evidence for symbolic expression of religious belief. This claim is evaluated in a variety of ways focusing on three themes: mobility, political structure and social complexity, and religious belief. This first attempt at continental scale expression of symbolic systems directly tied to conceptual metaphors and religious belief has resulted in the preliminary identification of a religious landscape among all the regions, to varying degrees throughout the Iron Age. These findings help explain the widespread distribution of ASA in north central Eurasia during the Iron Age.
227

A prototype system for ontology matching using polygons

Herrero, Ana January 2006 (has links)
When two distributed parties want to share information stored in ontologies, they have to make sure that they refer to the same concepts. This is done matching the ontologies. This thesis will show the implementation of a method for automatic ontology matching based on the representation of polygons. The method is used to compare two ontologies and determine the degree of similarity between them. The first of the ontologies will be taken as the standard, while the other will be compared to it by analyzing the elements in both. According to the degrees of similarity obtained from the comparison of elements, a set of polygons is represented for the standard ontology and another one for the second ontology. Comparing the polygons we obtain the final result of the similarity between the ontologies. With that result it is possible to determine if two ontologies handle information referred to the same concept.
228

Utilizing similarity information in industrial applications

Koskimäki, H. (Heli) 03 March 2009 (has links)
Abstract The amount of digital data surrounding us has exploded within the past years. In industry, data are gathered from different production phases with the intent to use the data to improve the overall manufacturing process. However, management and utilization of these huge data sets is not straightforward. Thus, a computer-driven approach called data mining has become an attractive research area. Using data mining methods, new and useful information can be extracted from enormous data sets. In this thesis, diverse industrial problems are approached using data mining methods based on similarity. Similarity information is shown to give an additional advantage in different phases of manufacturing. Similarity information is utilized with smaller-scale problems, but also in a broader perspective when aiming to improve the whole manufacturing process. Different ways of utilizing similarity are also introduced. Methods are chosen to emphasize the similarity aspect; some of the methods rely entirely on similarity information, while other methods just preserve similarity information as a result. The actual problems covered in this thesis are from quality control, process monitoring, improvement of manufacturing efficiency and model maintenance. They are real-world problems from two different application areas: spot welding and steel manufacturing. Thus, this thesis clearly shows how the industry can benefit from the presented data mining methods.
229

Time series data mining in systems biology

Tapinos, Avraam January 2013 (has links)
Analysis of time series data constitutes an important activity in many scientific disciplines. Over the last years there has been an increase in the collection of time series data in all scientific fields and disciplines, such as the industry and engineering. Due to the increasing size of the time series datasets, new automated time series data mining techniques have been devised for comparing time series data and present information in a logical and easily comprehensible structure.In systems biology in particular, time series are used to the study biological systems. The time series representations of a systems’ dynamics behaviour are multivariate time series. Time series are considered multivariate when they contain observations for more than one variable component. The biological systems’ dynamics time series contain observations for every feature component that is included in the system; they thus are multivariate time series. Recently, there has been an increasing interest in the collection of biological time series. It would therefore be beneficial for systems biologist to be able to compare these multivariate time series.Over the last decade, the field of time series analysis has attracted the attention of people from different scientific disciplines. A number of researchers from the data mining community focus their efforts on providing solutions on numerous problems regarding different time series data mining tasks. Different methods have been proposed for instance, for comparing, indexing and clustering, of univariate time series. Furthermore, different methods have been proposed for creating abstract representations of time series data and investigating the benefits of using these representations for data mining tasks.The introduction of more advanced computing resources facilitated the collection of multivariate time series, which has become common practise in various scientific fields. The increasing number of multivariate time series data triggered the demand for methods to compare them. A small number of well-suited methods have been proposed for comparing these multivariate time series data.All the currently available methods for multivariate time series comparison are more than adequate for comparing multivariate time series with the same dimensionality. However, they all suffer the same drawback. Current techniques cannot process multivariate time series with different dimensions. A proposed solution for comparing multivariate time series with arbitrary dimensions requires the creation of weighted averages. However, the accumulation of weights data is not always feasible.In this project, a new method is proposed which enables the comparison of multivariate time series with arbitrary dimensions. The particular method is evaluated on multivariate time series from different disciplines in order to test the methods’ applicability on data from different fields of science and industry. Lastly, the newly formed method is applied to perform different time series data mining analyses on a set of biological data.
230

Thermal Imaging As A Biometrics Approach To Facial Signature Authentication

Guzman Tamayo, Ana M 07 November 2011 (has links)
This dissertation develops an image processing framework with unique feature extraction and similarity measurements for human face recognition in the mid-wave infrared portion of the electromagnetic spectrum. The goal is to design specialized algorithms that would extract vasculature information, create a thermal facial signature and identify the individual. The objective is to use such findings in support of a biometrics system for human identification with a high degree of accuracy and a high degree of reliability. This last assertion is due to the minimal to no risk for potential alteration of the intrinsic physiological characteristics seen through thermal imaging. Thermal facial signature authentication is fully integrated and consolidates the main and critical steps of feature extraction, registration, matching through similarity measures, and validation through the principal component analysis. Feature extraction was accomplished by first registering the images to a reference image using the functional MRI of the Brain’s (FMRIB’s) Linear Image Registration Tool (FLIRT) modified to suit thermal images. This was followed by segmentation of the facial region using an advanced localized contouring algorithm applied on anisotropically diffused thermal images. Thermal feature extraction from facial images was attained by performing morphological operations such as opening and top-hat segmentation to yield thermal signatures for each subject. Four thermal images taken over a period of six months were used to generate a thermal signature template for each subject to contain only the most prevalent and consistent features. Finally a similarity measure technique was used to match images to the signature templates and the Principal Component Analysis (PCA) was used to validating the results of the matching process. Thirteen subjects were used for testing the developed technique on an in-house thermal imaging system. The matching using the similarity measures showed 88% accuracy in case of skeletonized feature signatures and 90% accuracy for anisotropically diffused feature signatures. The highly accurate results obtained in the matching process along with the generalized design process clearly demonstrate the ability of the developed thermal infrared system to be used on other thermal imaging based systems and related databases.

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