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A Hybrid Approach to Cross-Linguistic Tokenization: Morphology with StatisticsKearsley, Logan R. 01 June 2016 (has links)
Tokenization, or word boundary detection, is a critical first step for most NLP applications. This is often given little attention in English and other languages which use explicit spaces between written words, but standard orthographies for many languages lack explicit markers. Tokenization systems for such languages are usually engineered on an individual basis, with little re-use. The human ability to decode any written language, however, suggests that a general algorithm exists.This thesis presents simple morphologically-based and statistical methods for identifying word boundaries in multiple languages. Statistical methods tend to over-predict, while lexical and morphological methods fail when encountering unknown words. I demonstrate that a generic hybrid approach to tokenization using both morphological and statistical information generalizes well across multiple languages and improves performance over morphological or statistical methods alone, and show that it can be used for efficient tokenization of English, Korean, and Arabic.
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Zpracování tureckých jazyků / Processing of Turkic LanguagesCiddi, Sibel January 2013 (has links)
This thesis aims to present several combined methods for the morphological processing of Turkic languages, such as Turkish, which pose a specific set of challenges for computational processing, and also aims to make larger data sets publicly available. Because of the highly productive, agglutinative morphology in Turkish, data sparsity---besides the lack of the publicly available large data sets---impose difficulties in natural language processing, especially with regards to relying on purely statistical methods. Therefore, we evaluate a publicly available rule-based morphological analyzer, TRmorph, based on finite state transducers. In order to enhance the efficiency of this analyzer, and to expand its lexicon; we combine statistical and heuristics-based methods for the named entity processing (and construction of gazetteers), morphological disambiguation task and the multiword expression processing. Experiment results obtained so far point out that the use of heuristic-methods provides promising coverage increase for the text being processed by TRmorph, while the statistical approach is used as a back-up for more fine-grained tasks that may not be captured by pattern-based heuristics approach. This way, our proposed combined approach enhances the efficiency of a morphological analyzer based purely on FST...
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Morfometrická analýza Novohradských hor / Morphometric analysis of the Novohradské MountainsČÍŽEK, Ondřej January 2008 (has links)
This thesis deals with morphological analysis of the Novohradské Mountains. A part of the data necessary for this task was found out by means of field exploration. Results of measuring of joint system were compiled and rose-diagrams were created.
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Analyse de la morphologie axonale : du traitement des images à la modélisation / Axonal morphology analysis : from image processing to modellingMottini d'Oliveira, Alejandro Ricardo 30 September 2014 (has links)
L'analyse de la morphologie axonale est un problème important en neuroscience. Diverses études ont montré que les caractéristiques morphologiques de ces structures donnent des informations sur son fonctionnement et permettent la caractérisation d'états pathologiques. En conséquence, il est important de développer des méthodes pour étudier leurs formes et quantifier leurs différences structurelles.Dans cette thèse on propose une méthode pour la comparaison des arbres axonaux qui inclue des informations topologiques et géométriques. La méthode est fondée sur la théorie des formes élastiques. Avec cette approche, nous pouvons exhiber le chemin géodésique entre deux formes et la forme moyenne d'un ensemble d'échantillons. En outre, nous proposons un schéma de classification à partir de cette métrique que nous comparons à l'état de l'art. Finalement, nous proposons un modèle stochastique pour la simulation de la croissance axonale défini par une chaîne de Markov. Il considère 2 processus principaux qui modélisent l'élongation et forme de l'axone et la génération des branches. Le processus de croissance dépend de différentes variables, dont un champ externe d'attraction généré par certaines molécules dans l'environnement. Les deux techniques proposées ont été validées sur une base d'images de microscopie confocale de neurones chez la Drosophile. Des neurones normaux et modifiés génétiquement ont été considérés. Les résultats montrent que la méthode de comparaison proposée fournit de meilleurs résultats que les méthodes décrites dans la littérature. De plus, les paramètres du modèle donnent des informations sur le processus de croissance de chaque population d'axones. / The morphological analysis of axonal trees is an important problem in neuroscience. It has been shown that the morphological characteristics of thesestructures provide information on their functioning and allows the characterization of pathological states. Therefore, it is of great importance to develop methods to analyze their shape and to quantify differences between structures. In this thesis we propose a method for the comparison of axonal trees that takes into account both topological and geometrical information. Using this method, which is based on the Elastic Shape Analysis Framework, we can compute the geodesic path between two axons and the mean shape of a population of trees. In addition, we derive a classfication scheme based on this metric and compare it with state of the art approaches. Finally, we propose a 2D discrete stochastic model for the simulation of axonal biogenesis. The model is defined by a third order Markov Chain and considers two main processes: the growth process that models the elongation and shape of the neurites and the bifurcation process that models the generation of branches. The growth process depends, among other variables, on an external attraction field. Both techniques were validated on a database of real fluorescent confocal microscopy images of neurons within Drosophila fly brains. Both normal neurons and neurons in which certain genes were inactivated have been considered. Results show that the proposed comparison method obtains better results that other methods found in the literature, and that the model parameter values provide information about the growth properties of the populations.
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Electrophysiological and Morphological Analyses of Mouse Spinal Cord Mini-Cultures Grown on Multimicroelectrode PlatesHightower, Mary H. (Mary Helen) 12 1900 (has links)
The electrophysiological and morphological properties of small networks of mammalian neurons were investigated with mouse spinal cord monolayer cultures of 2 mm diameter grown on multimicroelectrode plates (MMEPs). Such cultures were viewed microscopically and their activity simultaneously recorded from 2 of any 36 fixed recording sites. The specific aims achieved were: development of techniques for production of functional MMEPs and maintenance of mini-cultures, characterization of the spontaneous activity of mini-cultures, application of inhibitory and disinhibitory agents, development of staining methods for cultured neurons and initial light microscopic analysis with correlation of electrophysiological and morphological characteristics.
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Phylogenetic and morphological analysis of the Afroedura nivaria (Reptilia: Gekkonidae) species complex in South AfricaMakhubo, Buyisile Getrude 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The Afroedura nivaria complex is one of the six recognized species complexes within a southern African endemic genus, Afroedura. The A. nivaria complex is a morphologically conservative group of medium-sized geckos endemic to South Africa though they are unevenly distributed in the Eastern Cape, Free State and KwaZulu-Natal provinces. The complex comprises the following five species: A. nivaria (Boulenger 1894), A. amatolica (Hewitt 1925), A. karroica (Hewitt 1925), A. tembulica (Hewitt 1926) and A. halli (Hewitt 1935). These nocturnal and rupicolous geckos shelter in narrow rock crevices on outcrops. It is currently unknown whether a) the described species are valid and b) if additional lineages are present on isolated outcrops. I investigated the hypothesis that endemics with a narrow distribution, that is, A. amatolica and A. tembulica are valid species but that isolated populations in the widespread species (A. nivaria, A. karroica and A. halli) demonstrate genetic variation at the species level. Fragments of two mitochondrial genes (16S rRNA and ND4) and a single nuclear marker (KIAA) were sequenced and analysed using Bayesian inference, maximum parsimony and maximum likelihood. All analyses strongly supported the genetic distinctiveness of the described species. The A. nivaria complex is not monophyletic, A. karroica appeared to be outside the species complex and A. pondolia (thought to be outside the A. nivaria complex) consistently nested within A. nivaria complex. Additional clades recovered in the phylogeny within A. halli and A. nivaria had large genetic divergences and no spatial overlap. Narrowly distributed A. amatolica showed to have two highly diverged clades. Clades recovered in the phylogeny highlight geographical structuring. These findings suggest the existence of up to four additional cryptic lineages within the complex. I used morphometric data (ecologically relevant morphological traits) to investigate whether the genetic lineages would present morphological conservatism. Multivariate analyses of 19 variables showed variation within the A. nivaria species complex was accounted for mostly by differences in locomotor apparatus (limbs and feet) and head dimensions. These traits are mostly related to microhabitat usage and/or dietary specialization in lizards. There were no significant differences for body dimensions between species within the complex, indicative of morphological conservatism. It appears genetic divergence has been achieved among the different clades within A. nivaria complex, but with much similarity in phenotype being retained because of fragmented but similar habitats occupied. / AFRIKAANSE OPSOMMING: Die Afroedura nivaria kompleks is een van ses herkende spesies komplekse binne die endemiese suidelike Afrika genus, Afroedura. Die A. nivaria kompleks is ‘n morfologiese konserwatiewe groep bestaande uit medium grootte geitjies endemies tot Suid Afrika, alhoewel hulle oneweredig verspreid is in die Oos Kaap, Vrystaat en Kwazulu-Natal provinsies. Die kompleks bestaan uit die volgende vyf spesies: A. nivaria (Boulenger 1894), A. amatolica (Hewitt 1925), A. karroica (Hewitt 1925), A. tembulica (Hewitt 1926) and A. halli (Hewitt 1935). Hierdie geitjies kom snags voor en skuil tussen nou skeure op klip koppies. Dit is tans onbekend of a) die beskryfde spesies geldig is en b) of die addisionele afstammelinge voorkom op geisoleerde koppies. Met die studie het ek die hipotese ondersoek dat endemiese spesies met ‘n noue verspreiding (A. amatolica en A. tembulica) geldige spesies is, maar dat spesies met ‘n wye verspreiding (A. nivaria, A. karroica and A. halli) genetiese variasie op spesie vlak wys. Fragmente van twee mitochondriale gene (16S rRNA and ND4) en ‘n enkele nuklêre merker (KIAA) se basispaaropeenvolgingsdata was verkry en geanaliseer deur Bayesian inferensie, maksimum parsimonie en maksimum waarskynlikheid. Alle analise het die genetiese kenmerkendheid van die beskryfde spesies sterk ondersteun. Die A. nivaria kompleks is monofileties, A. karroica het geblyk om buite die spesies kompleks voor te kom en A. pondolia (voorheen beskryf as buite die A. nivaria kompleks) het voortdurend binne die A. nivaria kompleks voorgekom. Addisionele klades afkomstig vanaf die filogenië van A. halli en A. nivaria het vir beide spesies groot genetiese divergensie met geen ruimtelike oorvleuling gewys. Afroedura amatolica, met sy noue verspreiding, het twee hoogs divergente klades getoon. Die klades onthul deur die filogenie beklemtoon ‘n geografiese struktuur. Hierdie bevindings blyk die bestaan van tot vier ekstra kriptiese afstammelinge binne die kompleks. Ek het morfometriese data (ekologiese relevante morfologiese eienskappe) gebruik om vas te stel of die genetiese afstammelinge morphologies konserwatief sal wees. Meerveranderlike analises op 19 veranderlikes het variasie binne die A. nivaria spesies kompleks getoon. Hierdie veranderinge was meestal gevind in die beweeglikheidsapparatuur (ledemate en voete) en kop dimensies. Die verskeie eienskappe hou meestal verband met die mikrohabitatte wat gebruik word en/of dieët spesialisering in akkedisse. Daar was geen noemenswaardige verskille in liggaamsdimensies tussen spesies in die kompleks nie, beduidend op ‘n konserwatiewe morfologie. Dit wil blyk of genetiese divergensie tussen die verskeie klades van die A. nivaria kompleks bewerkstellig is met ooreenstemming in die fenotipes as gevolg van gefragmenteerde maar soortgelyke habitat verbruik.
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Diversidade de cianobactérias em crostas biológicas e avaliação de perfil celulolítico e hemicelulolítico / Diversity of cyanobacteria in biological soil crusts and evaluation of cellulolytic and hemicellulolytic profileLima, Nathali Maria Machado de 31 October 2016 (has links)
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Previous issue date: 2016-10-31 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Crostas biológicas consistem de uma comunidade composta por cianobactérias, algas verdes, microfungos, bactérias, líquens e musgos. Estas ocorrem em uma variedade de solos e regiões climáticas ao redor do globo, exercendo funções importantes como a de conferir estabilidade e proteger o solo contra forças erosivas, acumular e aumentar o tempo de residência da água no solo, além de, favorecer a germinação e permitir a fixação de nitrogênio e carbono. Em crostas biológicas de regiões quentes e temperadas há o predomínio de líquens e cianobactérias, sendo que as cianobactérias são consideradas os primeiros organismos a estruturarem a crosta, sendo seguidas por outros grupos de organismos. A partir da investigação de cianobactérias em crostas biológicas, muitos novos gêneros e espécies têm sido descritos, o que também enfatiza a grande necessidade da investigação sobre tais comunidades. Devido às condições propícias do ambiente, em termos de exposição do solo e fitofisionomia, o bioma Cerrado (Savana) foi escolhido para ser o local de estudo de assembleias de cianobactérias de crostas. Além disso, devido a estudos prévios que relatam o potencial de produção de enzimas celulolíticas e hemicelulolíticas por cianobactérias heterocitadas e a presença comum deste tipo de organismos em crostas biológicas, também foram feitas análises para avaliar a produção de tais substâncias. Desse modo, os estudos objetivaram contribuir com conhecimento da biodiversidade de cianobactérias de crostas biológicas de solo e avaliar a capacidade de produção enzimática das cianobactérias encontradas em crostas biológicas de solo. Para isto, amostras de crostas foram coletadas nos Parques Nacionais da Serra da Canastra (MG) e da Serra do Cipó (MG), no Parque Estadual Furnas do Bom Jesus (SP) e na região de Caldas Novas (GO). As cianobactérias encontradas nas amostras foram estudadas morfologicamente a partir do material da natureza e também isoladas em cultivos artificiais, visando além do estudo morfológico, as análises moleculares e enzimáticas. No total, foram estudados 28 morfotipos, provenientes de 31 populações, dos quais 12 foram identificados em nível específico (destes, três ainda exigem confirmação de identidade = cf) e 16 foram identificados apenas em nível genérico. Dezenove populações foram analisadas também em nível molecular por meio do sequenciamento parcial do gene 16S rRNA, e completo da Região Espaçadora Interna Transcrita 16S-23S (ITS). Seis populações foram também investigadas quanto a produção de enzimas. Entre os gêneros encontrados, muitos são comuns em assembleias de cianobactérias de crostas biológicas em outras regiões do mundo, entretanto, algumas identificações em nível de espécie não foram possíveis por diferenças importantes com os táxons já descritos em literatura. As análises moleculares enfatizaram e contribuíram com a problemática polifilia de gêneros como Leptolyngbya, Nostoc e Calothrix, reafirmaram a existência de um novo gênero próximo a Wilmottia e Microcoleus e apresentaram um novo grupo composto até o momento por uma espécie representada por duas populações. Este grupo revelou sequências moleculares que se aproximam de Brasilonema, entretanto os indivíduos apresentam ramificações verdadeiras e, portanto, investigações mais aprofundadas são necessárias para definição da identidade das populações. Dessa forma, as análises morfológicas e moleculares demonstraram a grande diversidade não acessada em localidades e habitats pobremente investigados e enfatizaram a contribuição deste trabalho ao enfocar pela primeira vez a flora de cianobactérias de solo de Cerrado. As análises de atividade enzimática revelaram que não houve produção de tais proteínas, tendo como possíveis explicações a ausência de habilidade para produção deste tipo de enzimas por parte das cepas, ou a ineficiência do método utilizado. De qualquer forma os resultados enfatizaram a necessidade de estudo nesta área, principalmente pela dificuldade no encontro de cepas produtoras e o desconhecimento sobre quais poderiam ser os fatores a estarem influenciando certas cepas a ativarem ou selecionarem diferentemente seus metabolismos. Em linhas gerais, os resultados do presente estudo apresentam, pela primeira vez, a composição das cianobactérias de crostas biológicas do território brasileiro e indicam uma flora diversificada e, em grande parte, desconhecida. Esses resultados fornecem subsídios e abrem caminho para outras pesquisas dentro do campo do conhecimento da biodiversidade presente em crostas biológicas. Complementarmente, estes trabalhos compõem a base para estudos sobre a ecologia de ambientes mais restritivos (como a caatinga ou o próprio Cerrado), permitindo abordagens como sucessão ecológica, produtividade primária, fluxos de nutrientes e dinâmicas de solo. / Biological soil crusts (BSCs) are communities potentially composed of cyanobacteria, green algae, micro fungi, bacteria, lichens and mosses. They occur in a variety of soils and climatic regions around the world, playing important roles as giving soil stability protecting against erosive forces, accumulating and increasing residence time for water in soil, besides promoting germination and performing nitrogen and carbon fixation. Biological soil crusts from hot deserts are frequently composed of cyanobacteria and lichens, and the cyanobacteria are considered the first colonizers in structuring the crust, being followed by other groups of organisms. A lot of new genera and species have been described based on crusts investigations and this fact also emphasizes the necessity of works on those communities. Due to environmental conditions, as soil exposition and phytophysiognomy, the biome Cerrado (Savannah) was chosen to be the place for studies on cyanobacterial assemblages of biological soil crusts. Besides, due to previous studies that indicate the production capability of celulolitic and hemicelulolitic enzymes by heterocytous cyanobacteria and the common presence of this kind of cyanobacteria in biological soil crusts, analyses of such production were also conducted. In this way, the studies aimed to contribute with knowledge about cyanobacterial biodiversity in biocrusts and evaluate the bioprospection capability of cyanobacterial from these biocrusts. Therefore, BSCs were sampled at the National Parks of Serra da Canastra (Minas Gerais State) and Serra do Cipó (Minas Gerais State), at the State Park of Furnas do Bom Jesus (São Paulo State) and in the region of the municipality of Caldas Novas (Goiás State). The cyanobacteria found in the samples had their morphology analyzed from the natural and cultivated conditions. Besides, molecular and enzymatic analysis were carried out. The results summarized 28 morphotypes from 31 populations, which 12 were identified at specie level (three of them need identity confirmation = cf) and 16 were identified only at genus level. Nineteen populations also were studied with molecular methods, through partial sequencing of 16S rRNA gene and complete sequencing of the Internal Transcribed Space Region (16S-23S ITS). In addition, six populations also were explored as possible enzymatic producers. Among the found genera, many are cyanobacteria frequently found in BSCs distributed around the world, however, some identifications at specific level were not possible due to considerable divergences in comparison with described taxa. The molecular analysis reaffirmed and emphasized the polyphyletic nature of Leptolyngbya, Nostoc and Calothrix, reinforced the existence of a new genus close related with Wilmottia and Microcoleus and presented a new group composed, until now, of one species represented by two populations. This group showed molecular sequences related with Brasilonema, however, the specimens are true branched, what requires more detailed studies to confirm the identification of the populations. In this way, the morphological and molecular analyses showed the wide diversity whose has not been accessed in poorly investigated places and habitats and reinforced the contribution of this work in focusing the cyanobacterial flora of crusts of Brazilian savannah area for the first time. The enzymatic activity analysis revealed that the strains studied did not produce celulolitic or hemicelulolitic compounds, having as possible explanations the absence of the production ability or the inefficiency of the utilized method. Either way, the results emphasized the necessity of studies in this area, mainly because of the difficulty in find producer strains and the lack of knowledge about which could be the factors influencing the strains in activate or select differently their metabolism. In general, our results presented for the first time the cyanobacterial composition for BSCs from Brazil and indicated a diverse, and sometimes, unknown flora. These results provided foundation and opened doors to investigations inside the biodiversity knowledge with biological soil crusts. Complementary, these works compound the basis for investigations in the ecology of extreme environments (as Caatinga and Cerrado), permiting studies about successional ecology, primary productivity, flow of nutrients and soil dynamics. / 2014/06245-8
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Sistemática do gênero Gymnanthes Sw. (Hippomaneae, Euphorbiaceae)OLIVEIRA, Luciana dos Santos Dias de 26 February 2014 (has links)
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Previous issue date: 2014-02-26 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Hippomaneae is one of the most diverse and complex tribes of Euphorbioideae subfamily (Euphorbiaceae). Of its 33 genera, about 10 have not yet been reviewed and with problematic boundaries. Among these, stood out Gymnanthes to be considered one of the most difficult taxonomy of genera of the tribe, as a result of intra- and intergeneric limits poorly understood and present several nomenclatural and classification problems. In this sense, this thesis aimed to review the neotropical species of Gymnanthes from the morphological analysis. We examined about 5,000 specimens from 93 herbaria, of which 36 were visited, and specimens collected in the field. The results are presented in the form of four papers. (1) In the study of taxonomic revision, a new constituency for Gymnanthes is hereby established which shall comprise 16 species versus the 45 estimated in previous treatments. Of these, 12 species are found in the Neotropics, two in Africa and two in Asia, with the greatest diversity in Central America (8 spp). 26 are proposed sinonimizações five new combinations lectotipificações and 27, and a neotype. Eight names were excluded from the concept of Gymnanthes and transferred to Actinostemon. (2) In the second manuscript, was performed to lectotipificação of Gymnanthes klotzschiana and the transfer of Actinostemon unciformis for your concept. (3) Based on the analysis of species Actinostemon, gender near Gymnanthes, was described in the third article, the species A. roselii. This is easily recognized by the size of staminate címulas bracts, the globoid leaf buds and in the presence of sepals staminate flowers and pistillate. Finally, (4) the last item brought the mapping of the geographical distribution of Gymnanthes boticario, a well-collected species, but just described. It was observed that Gymnanthes boticario shows a distribution pattern associated with semi-arid environments, more precisely the dry forests. A correlation of their distribution with the theory of Pleistocenic Arc was still drawn. It was found that G. boticario supports the Pleistocene theory by presenting a pattern of disjunct distribution within the field of dry forests. Were also cited the first G. boticario records in Bolivia, Paraguay and the Pantanal hillside forests (Mato Grosso do South). The work also addressed the fact that the new species to be described are not necessarily rare or endemic taxa strictly, as reported in the literature. Although Gymnanthes boticario have been described recently (2010), were found by the year of its publication, 81 fish over 18 herbal over 50 duplicates found in 21 institutions, resulting in a total of 131 herbarium specimens distributed in 25 herbaria six different countries (Germany, Bolivia, Brazil, USA, UK and Switzerland). Soon, G. boticario is a common kind of example and well collected that took a long time to be recognized as a new taxon, showing that the new species remain to be described are not necessarily endemic or remote areas with difficult access. / Hippomaneae é uma das tribos mais diversas e complexas da subfamília Euphorbioideae (Euphorbiaceae). Dos seus 33 gêneros, cerca de 10 ainda não foram revisados e apresentam delimitações problemáticas. Dentre estes, destacava-se Gymnanthes por ser considerado um dos gêneros de taxonomia mais difícil da tribo, em decorrência de limites intra e intergenéricos pouco compreendidos e por apresentar diversos problemas nomenclaturais e de tipificação. Neste sentido, a presente tese teve como objetivo revisar as espécies neotropicais de Gymnanthes a partir da análise morfológica. Foram examinados cerca de 5.000 exemplares provenientes de 93 herbários, dos quais 36 foram visitados, além de espécimes coletados em campo. Os resultados são apresentados na forma de quatro artigos científicos. (1) No estudo de revisão taxonômica, uma nova circunscrição para Gymnanthes é aqui estabelecida que passa a compreender 16 espécies em contraposição as 45 estimadas em tratamentos anteriores. Dessas, 12 espécies são encontradas nos Neotrópicos, duas na África e duas na Ásia, com maior diversidade na América Central (8 spp). São propostas 26 sinonimizações, cinco novas combinações e 27 lectotipificações, além de um neótipo. Oito nomes foram excluídos do conceito de Gymnanthes e transferidos para Actinostemon. (2) No segundo manuscrito, foi procedida a lectotipificação de Gymnanthes klotzschiana e a transferência de Actinostemon unciformis para o seu conceito. (3) A partir da análise de espécies de Actinostemon, gênero próximo de Gymnanthes, foi descrito, no terceiro artigo, a espécie A. roselii. Esta é facilmente reconhecida pelo tamanho das brácteas das címulas estaminadas, pelas gemas foliares globoides e pela presença de sépalas nas flores estaminadas e pistiladas. Por fim, (4) o último artigo trouxe o mapeamento da distribuição geográfica de Gymnanthes boticario, uma espécie bem coletada, mas recém-descrita. Foi observado que Gymnanthes boticario apresenta um padrão de distribuição associado a ambientes semiáridos, mais precisamente as Florestas Secas. Uma correlação da sua distribuição com a teoria do Arco Pleistocênico foi ainda traçada. Verificou-se que G. boticario corrobora a teoria pleistocênica por apresentar um padrão de distribuição disjunto dentro do domínio das Florestas Secas. Foram ainda citados os primeiros registros de G. boticario na Bolívia, Paraguai e para as florestas de encosta do Pantanal (Mato Grosso do Sul). O trabalho também abordou o fato de que as novas espécies a serem descritas não são necessariamente táxons raros ou estritamente endêmicos, como relatado na literatura. Apesar de Gymnanthes boticario ter sido descrita recentemente (2010), foram encontrados, até o ano da sua publicação, 81 espécimes distribuídos em 18 herbários com mais de 50 duplicatas encontradas em 21 instituições, resultando num total de 131 exsicatas distribuídas em 25 herbários de seis países diferentes (Alemanha, Bolívia, Brasil, Estados Unidos, Inglaterra e Suíça). Logo, G. boticario é um exemplo de espécie comum e bem coletada que levou muito tempo para ser reconhecida como um novo táxon, demostrando que as espécies novas que ainda restam para serem descritas não são necessariamente endêmicas ou de áreas distantes e de difícil acesso.
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Morphology-based Fault Feature Extraction and Resampling-free Fault Identification Techniques for Rolling Element Bearing Condition MonitoringSHI, Juanjuan January 2015 (has links)
As the failure of a bearing could cause cascading breakdowns of the mechanical system and then lead to costly repairs and production delays, bearing condition monitoring has received much attention for decades. One of the primary methods for this purpose is based on the analysis of vibration signal measured by accelerometers because such data are information-rich.
The vibration signal collected from a defective bearing is, however, a mixture of several signal components including the fault-generated impulses, interferences from other machine components, and background noise, where fault-induced impulses are further modulated by various low frequency signal contents. The compounded effects of interferences, background noise and the combined modulation effects make it difficult to detect bearing faults. This is further complicated by the nonstationary nature of vibration signals due to speed variations in some cases, such as the bearings in a wind turbine. As such, the main challenges in the vibration-based bearing monitoring are how to address the modulation, noise, interference, and nonstationarity matters. Over the past few decades, considerable research activities have been carried out to deal with the first three issues. Recently, the nonstationarity matter has also attracted strong interests from both industry and academic community. Nevertheless, the existing techniques still have problems (deficiencies) as listed below:
(1) The existing enveloping methods for bearing fault feature extraction are often adversely affected by multiple interferences. To eliminate the effect of interferences, the prefiltering is required, which is often parameter-dependent and knowledge-demanding. The selection of proper filter parameters is challenging and even more so in a time-varying environment.
(2) Even though filters are properly designed, they are of little use in handling in-band noise and interferences which are also barriers for bearing fault detection, particularly for incipient bearing faults with weak signatures.
(3) Conventional approaches for bearing fault detection under constant speed are no longer applicable to the variable speed case because such speed fluctuations may cause “smearing” of the discrete frequencies in the frequency representation. Most current methods for rotating machinery condition monitoring under time-varying speed require signal resampling based on the shaft rotating frequency. For the bearing case, the shaft rotating frequency is, however, often unavailable as it is coupled with the instantaneous fault characteristic frequency (IFCF) by a fault characteristic coefficient (FCC) which cannot be determined without knowing the fault type. Additionally, the effectiveness of resampling-based methods is largely dependent on the accuracy of resampling procedure which, even if reliable, can complicate the entire fault detection process substantially.
(4) Time-frequency analysis (TFA) has proved to be a powerful tool in analyzing nonstationary signal and moreover does not require resampling for bearing fault identification. However, the diffusion of time-frequency representation (TFR) along time and frequency axes caused by lack of energy concentration would handicap the application of the TFA. In fact, the reported TFA applications in bearing fault diagnosis are still very limited.
To address the first two aforementioned problems, i.e., (1) and (2), for constant speed cases, two morphology-based methods are proposed to extract bearing fault feature without prefiltering. Another two methods are developed to specifically handle the remaining problems for the bearing fault detection under time-varying speed conditions. These methods are itemized as follows:
(1) An efficient enveloping method based on signal Fractal Dimension (FD) for bearing fault feature extraction without prefiltering,
(2) A signal decomposition technique based on oscillatory behaviors for noise reduction and interferences removal (including in-band ones),
(3) A prefiltering-free and resampling-free approach for bearing fault diagnosis under variable speed condition via the joint application of FD-based envelope demodulation and generalized demodulation (GD), and
(4) A combined dual-demodulation transform (DDT) and synchrosqueezing approach for TFR energy concentration level enhancement and bearing fault identification.
With respect to constant speed cases, the FD-based enveloping method, where a short time Fractal dimension (STFD) transform is proposed, can suppress interferences and highlight the fault-induced impulsive signature by transforming the vibration signal into a STFD representation. Its effectiveness, however, deteriorates with the increased complexity of the interference frequencies, particularly for multiple interferences with high frequencies. As such, the second method, which isolates fault-induced transients from interferences and noise via oscillatory behavior analysis, is then developed to complement the FD-based enveloping approach. Both methods are independent of frequency information and free from prefiltering, hence eliminating the tedious process for filter parameter specification. The in-band vibration interferences can also be suppressed mainly by the second approach. For the nonstationary cases, a prefiltering-free and resampling-free strategy is developed via the joint application of STFD and GD, from which a resampling-free order spectrum can be derived. This order spectrum can effectively reveal not only the existence of a fault but also its location. However, the success of this method relies largely on an effective enveloping technique. To address this matter and at the same time to exploit the advantages of TFA in nonstationary signal analysis, a TFA technique, involving dual demodulations and an iterative process, is developed and innovatively applied to bearing fault identification.
The proposed methods have been validated using both simulation and experimental data collected in our lab. The test results have shown that the first two methods can effectively extract fault signatures, remove the interferences (including in-band ones) without prefiltering, and detect fault types from vibration signals for constant speed cases. The last two have shown to be effective in detecting faults and discern fault types from vibration data collected under variable speed conditions without resampling and prefiltering.
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Zelená perspektiva. Variace zeleného politického myšlení v Česku / Green Perspective. Variations of Green Political Thinking in the Czech RepublicKřížkovský, Matyáš January 2016 (has links)
The presented work is devoted to the development of Czech environmental movement in 1990's which is accompanied by academic debate about de-radicalisation. The aim of the thesis is to explore what sort of particular changes in the field of political ideas could be identified behind notional de-radicalisation. For this purpose is first laid out the historical context within which the movements were created onto their political ideals. It is followed by an introduction of the theoretical approaches to analyse these ideologies, outlining the basic methodological assumptions for a morphological analysis of the journals of Hnuti Duha. This analysis shows that between the periods 1991-1994 and 1998-2000 can be seen significant ideological transformations that are linked both with the inclination to certain elements of conservative thought and partly an inclination to a non-political politics. Key words green political thinking, ideology, morphological analysis, environmental movement
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