Dissertationen zum Thema „Structure zonales“
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Sama, Juvert Njeck. „The effect of beta on the nonlinear generation of zonal structures in experimentally relevant tokamak plasmas“. Electronic Thesis or Diss., Université de Lorraine, 2024. https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2024_0111_SAMA.pdf.
Der volle Inhalt der QuelleSpatial gradients in temperature and density in tokamak plasmas excite micro-instabilities, which interact non-linearly to form turbulence. Turbulence increases heat and particle transport, reducing the energy confinement time. Understanding turbulence dynamics is important to achieving the conditions for self-sustained combustion in a fusion reactor. Zonal structures (ZS), i.e., the axisymmetric perturbations of a tokamak plasma, are generated by turbulence and play an important role in its self-consistent saturation. Two types of ZS exist: zero-frequency zonal flows (ZFZF) and geodesic acoustic modes (GAM). Recent electrostatic nonlinear studies of turbulence-excited GAMs in Asdex upgrade (AUG) have shown that radially extended GAM structures can be excited by turbulence. The dynamics of GAMs have recently been shown to change when going from low confinement mode (L-mode) to intermediate confinement mode (I-mode) and from I-mode to high confinement mode (H mode). In particular, GAMs are observed experimentally in L-mode and I-mode and are more rarely observed in H-mode. A first linear model explaining this behavior was constructed using the combination of their Landau and continuum damping, which affects GAMs more strongly in H mode. Zonal structures generated by the GAM modes can interact and couple with the zonal structures generated by the turbulence induced by the instabilities, such as the so-called ITG (Ion Temperature Gradient) type modes. Kinetic and particle trapping effects can oppose Landau damping and dominate the zonal flow dynamics generated by ITGs. It is particularly important to understand the dynamics of zonal flows, their excitation mechanism, and their interaction with different plasma instabilities and turbulence. In this thesis, the dynamics of GAMs and ZFZF are studied in different configurations. In Chapter Two, we study the linear dynamics of geodesic acoustic modes in anisotropic plasma. We studied the effects of ion temperature anisotropy that can be introduced by various plasma heating mechanisms, such as neutral beam injection (NBI), ion cyclotron resonance heating (ICRH), and electron cyclotron resonance heating (ECRH). We show that ion temperature anisotropy can significantly modify the damping rate of the geodesic acoustic mode. In the third chapter of this thesis, we developed a global linear theory to study the linear dynamics of plasma waves in tokamak geometry for arbitrary particle distribution functions. We report a generalized expression of the GAM frequency in terms of the distribution function of the ion species and the mode. The generalized mode structure equation of the Alfven/ITG mode structure equation is in the large poloidal mode number unit. In chapter four, the numerical simulation code ORB5 is discussed in detail, pointing out all assumptions and domains of applicability. In chapter five. Our main focus was investigating the impact of zonal flows forced-driven by Alfven modes on linear ITG instabilities. We isolated this effect from self-consistent nonlinear electromagnetic simulations and tested it independently using a set of numerical tools that will be discussed later. We show that zonal flows forced-driven by Alfven modes can significantly mitigate ITG instabilities in an experimentally relevant scenario magnetic geometry. In chapter six, we review the "particle mode" model. We show that the synchronization of particle modes leads to the amplification of the zonal flows, which occurs even when the ions and electrons admit to the same temperature
Uzawa, Ken. „Study of modulational instability and structure of zonal flows in fusion plasmas“. Kyoto University, 2008. http://hdl.handle.net/2433/135587.
Der volle Inhalt der Quelle0048
新制・課程博士
博士(エネルギー科学)
甲第13952号
エネ博第173号
新制||エネ||40(附属図書館)
UT51-2008-C868
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 岸本 泰明, 教授 近藤 克己, 教授 福山 淳
学位規則第4条第1項該当
Laage, de Meux Benoît de. „Modélisation des écoulements turbulents en rotation et en présence de transferts thermiques par approche hybride RANS/LES zonale“. Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2012. https://theses.hal.science/docs/00/74/35/42/PDF/these_de_Laage.pdf.
Der volle Inhalt der QuelleThe numerical simulation of turbulent flows in cooling system of hydrau- lic pumps sealing requires considering large computational domains and long integration times. The zonal hybrid RANS/LES modelling of turbulence could deal with such appli- cations, in order to reproduce the whole thermal and dynamical phenomena of the flow, with a computational cost compatible with industrial studies. This approach aims at pro- perly interfacing a Large Eddy Simulation (LES), which provides an accurate unsteady description of turbulence in some critical regions of the flow, with the statistical RANS approach, less demanding in computational resources, applied in the whole remaining fluid domain in order to take into account the imposed global variations of the flow (cool water injection in hot water, shaft and rotor rotation,. . . ). To this end, a detailed study of tur- bulence models appropriate for rotating flows is presented, following both the RANS and the LES approaches. Numerous turbulence models are compared in the rotating channel flow test case. The zonal coupling at boundary faces using the Synthetic Eddy Method (SEM) is studied and an innovative volumic coupling using a source term on overlapping RANS/LES area, the Anisotropic Linear Forcing, is proposed. For the first time, these two coupling methods are extended to heat transfer. The present zonal hybrid RANS/LES computations of static or rotating channel flows in isothermal or forced convection regimes, show the applicability of such modelling for industrial studies
FERREIRA, Débora Maria Cavalcanti. „Delimitação de espécie e filogeografia do complexo Cryptanthus zonatus (Vis.) Vis. (BROMELIACEAE)“. Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18517.
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CAPES
Cryptanthus Otto & A.Dietr. (Bromeliaceae, Bromelioideae) é um gênero endêmico do Brasil. Cryptanthus burle-marxii Leme e C. zonatus (Vis.) Vis. são restritas ao norte da Floresta Atlântica nordestina e não apresentam delimitação taxonômica bem definida, pois muitos de seus caracteres morfológicos se sobrepõem. Ambas as espécies compõem o complexo C. zonatus (Vis.) Vis.. O objetivo do presente estudo foi realizar a delimitação de espécies e descrever os padrões filogeográficos do complexo C. zonatus, utilizando dados morfológicos, moleculares e de modelagem de nicho ecológico. Para o estudo foram feitos testes de amplificação heteróloga em C. burle-marxii e C. zonatus, utilizando 38 locos de microssatélites nucleares de cinco espécies de Bromeliaceae. Dos 38 locos testados, 24 apresentaram amplificação positiva e 13 foram polimórficos. Dez locos polimórficos foram selecionados para serem amplificados e genotipados em 147 indivíduos de oito populações do complexo C. zonatus. O resultado da análise morfológica e de estrutura genética mostrou que C. burle-marxii e C. zonatus são dois nomes dados à mesma espécie. A análise filogeográfica mostrou que a distribuição geográfica e estrutura genética do complexo C. zonatus pode ter sofrido modificações no quaternário. No último máximo glacial a distribuição geográfica potencial do complexo era contínua e maior em algumas áreas que atualmente é mar, o que deve ter ocorrido provavelmente devido à regressão marinha neste local. No Holoceno médio houve a potencial separação da distribuição possivelmente devido a uma barreira ecológica que perdurou até o presente formando dois grupos geneticamente estruturados, um ao norte e outro ao sul. Para a conservação da espécie foram indicadas populações prioritárias para o estabelecimento de unidades de conservação.
Cryptanthus Otto & A.Dietr. (Bromeliaceae, Bromelioideae) is an endemic genus from Brazil. Cryptanthus burle-marxii Leme and C. zonatus (Vis.) Vis. are species restricted to the north of the northeastern Atlantic Forest and have no well-defined taxonomic delimitation due to overlaping of some morphological characters. Both species are included in the Cryptanthus zonatus complex. The main goal of this study was to delimit species boudaries and to describe the phylogeographic patterns of the complex C. zonatus using morphological, molecular and ecological niche modeling data. For this study were carried out cross-amplification tests in C. burle-marxii and C. zonatus using 38 loci of nuclear microsatellite of five species of Bromeliaceae. Of the 38 loci tested, 24 showed positive amplification and 13 were polymorphic. Ten polymorphic loci were selected to be amplified and genotypes in 147 individuals from eight populations of the complex C. zonatus. The results of the morphological and genetic structure analyses showed that C. burle-marxii and C. zonatus are two names given to the same species. The phylogeographic analysis showed that the geographic distribution and genetic structure of the complex C. zonatus may have been modified in the Quaternary. The potential geographic distribution of the complex in the last glacial maximum was continuous and larger in some areas which are sea in present, what have probably occurred due to marine regression at this location. In the middle Holocene, there was the potential separation of distribution, possibly due to an ecological barrier that lasted until the present, forming two genetically structured groups, one in the north and other in the south. For conservation of the species priority populations were indicated for the establishment of protected areas
Galán, Fiestas Mary Isabel, und Jaimes Marco Antonio Nieto. „Concreto de baja permeabilidad para pilotes prefabricados de muelles construidos en zonas de salpicaduras y mareas utilizando nanotubos de carbono de pared múltiple“. Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/651959.
Der volle Inhalt der QuelleDue to the importance of the maritime structures, it is required that the concrete with which they are manufactured guarantees their impermeability against the waters of the sea, being the piles of the docks those that suffer different anomalies when being in direct contact with the sulfates and chlorides, that progressively degrade it mainly causing its cracking. Carbon Nanotubes (NTC) have a large specific surface that affects the cement matrix by modifying hydrated calcium silicates, producing greater cohesion and consequently increasing the compactness of concrete. The present work seeks to reduce the permeability of the concrete of the prefabricated piles of the springs located in areas of splashes and tides, studying for it different physical and mechanical properties of the concrete with NTC; The results indicate that settlement decreases, compressive, tensile and flexural strengths increase and water penetration depth decreases.
Trabajo de investigación
Risbey, James S. (James Sydney). „An analysis of zonal mean atmospheric angular momentum and high cloud cover : periodicities, time-latitude structure, and cross correlations“. Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/57727.
Der volle Inhalt der QuelleFigueiredo, Gabriela Guerra Araújo Abrantes de. „Variação na estrutura trófica e no uso dos recursos alimentares da ictiofauna de zonas rasas ao longo de um gradiente estuarino-límnico“. reponame:Repositório Institucional da FURG, 2014. http://repositorio.furg.br/handle/1/6114.
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O estudo da estrutura trófica de comunidades biológicas nos fornece uma descrição da organização e funcionamento do ecossistema e das interações entre as comunidades. Comparar a estrutura trófica das comunidades ao longo de gradientes ambientais pode fornecer novas interpretações em relação a sua organização trófica e serve de base para avaliar impactos antrópicos presentes e futuros. Um dos métodos mais comuns atualmente para se avaliar relações tróficas é a análise dos isótopos estáveis (AIE), o qual vem sendo utilizado para estimar os fluxos de matéria orgânica entre consumidores bem como sua posição trófica na cadeia alimentar. O objetivo principal dessa dissertação foi investigar a estrutura trófica da assembleia de peixes de zonas rasas ao longo de um gradiente estuarino–límnico, a partir da AIE de carbono (13C/12C) e nitrogênio (15N/14N) de fontes alimentares basais (i.e., plantas com fotossíntese C3 e C4 e matéria orgânica particulada em suspensão, POM) e peixes dominantes em cada sistema. Amostras de fontes alimentares basais, peixes e invertebrados foram coletados na primavera e verão entre 2009 e 2010 no estuário da Lagoa dos Patos, Canal São Gonçalo e Lagoa Mirim no extremo sul do Rio Grande do Sul. Biplots e métricas isotópicas (Convex hull e nicho isotópico) foram utilizadas para descrever e comparar a estrutura trófica da ictiofauna entre os ambientes. Análises de correlação foram realizadas para analisar a relação entre o comprimento total (CT) da ictiofauna e a posição trófica (PT). Modelos bayesianos de mistura isotópica foram empregados para avaliar a variabilidade no uso de recursos alimentares ao longo do gradiente ambiental para o barrigudinho Jenynsia multidentata, uma das únicas espécies frequentes ao longo de todo gradiente. A área total (Convex hull) e o nicho isotópico ocupado pela assembleia de peixes variaram marcadamente entre os ambientes, com o estuário apresentando uma área total duas vezes maior (CH: 50,28) do que o Canal e a Lagoa (17,51 e 20,29, respectivamente). Já o nicho isotópico, que é robusto aos efeitos de possíveis diferenças no número amostral, apresentou diferenças estatísticas entre estuário e os dois ambientes de água doce (p<0,00), porém esses dois últimos não apresentaram diferenças entre si (p>0,30). A AIE dos peixes no Canal sugere que a fragmentação de habitat ocasionada pela presença de uma barragem-eclusa afetou também a conectividade trófica entre o estuário da Lagoa dos Patos e Lagoa Mirim. Variações na razão isotópica do nitrogênio da comunidade também sugerem que impactos antrópicos como a eutrofização são mais acentuados no estuário da Lagoa dos Patos e Canal. As análises de correlações não mostraram correlação positiva entre o CT e PT. O modelo de mistura mostrou que as principais fontes alimentares basais para J. multidentata no canal foi POM, enquanto na lagoa foram principalmente plantas C4 e POM e no estuário houve uma maior sobreposição nos intervalos de credibilidade, não sendo possível distinguir diferenças significativas na contribuição relativa das fontes basais para a espécie. Nossos resultados mostraram que há diferenças na estrutura trófica e no uso de recursos alimentares ao longo do gradiente ambiental e que impactos antrópicos, como construção de barragem e eutrofização, afetam a ictiofauna nesses ambientes.
Trophic structure analyses of biological communities provide insights on ecosystem organization and functioning and also on communities’ interactions. Comparing the trophic structure of communities considering environmental gradients allows new interpretations of their trophic organization and evaluation of current and future anthropic impacts. One of the most common methods to evaluate trophic relationships is the stable isotope analysis (SIA), which has been used to estimate the flow of organic matter among consumers as well as its trophic position in the food chain. The main objective of this Master Thesis was to investigate the trophic structure of shallow areas fish assemblage along a freshwater-estuarine gradient, using the analysis of carbon (13C/12C) and nitrogen (15N/14N) isotope ratios of basal food sources (i.e., plants with C3 and C4 photosynthesis and particulate organic matter POM) and dominant fishes in each system. Basal food sources, fishes and invertebrates were collected at Lagoa dos Patos estuary, São Gonçalo Channel and Lagoa Mirim, located in the southern most in Brazil, during spring and summer seasons of 2009 and 2010. Biplots and isotopic metrics (Convex hull and isotopic niche) were used to describe and compare the trophic structure obtained in the three environments. Correlation analyzes were conducted to examine the relationship between total length (TL) of the ichthyofauna and trophic position (TP). Bayesian models of isotopic mixing were used to evaluate the variability in food resource use by the one-sided livebearer Jenynsia multidentata along the environmental gradient, which was one of the only species found along the entire gradient. The total area (Convex hull) and the isotopic niche occupied by the fish assemblage showed an marked variation among environments. The Convex hull total area of the estuary (CH: 50.28) was two-fold higher than the Channel and Lagoa Mirim areas (17,51 and 20.29, respectively). The isotopic niche, which is not affected by differences in sample sizes, showed statistical differences between the estuary and the two freshwater systems ( (p<0.00), but there were no statistical differences when the freshwater systems were compared with each other (p>0.30). The SIA analysis of fishes in the Channel suggests that the habitat fragmentation caused by a dam also affected the trophic connectivity between the Lagoa dos Patos estuary and the Lagoa Mirim. Comparison of the nitrogen isotope ratio values among communities also suggested that anthropogenic impacts (e.g., eutrophication) were more evident in the Lagoa dos Patos estuary and Channel. The analysis of correlations didn't show any positive correlation between TL and TP. The mixing model showed that the main basal food sources sustaining J. multidentata in the Channel was POM, whereas in the Lagoa Mirim was mainly C4 plants and POM. Moreover, in the estuary, it was found a greater overlap on the credibility intervals of basal food sources and it was not possible to distinguish statistical differences between their relative contributions to the specie. Our results showed that there are differences on the trophic structure and on the use of food resources along the environmental gradient. Also, anthropogenic impacts, such as dam constructions and eutrophication, have an affect on the ichthyofauna of these environments.
Fujisaki, Érica Tieko. „Produção primária e estrutura da comunidade fitoplanctônica nas zonas limnética e litorânea da represa Álvaro de Souza Lima (Bariri, SP) em quatro épocas do ano“. Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-25012017-160020/.
Der volle Inhalt der QuelleTemporal and spacial variations of phytoplankton primary production in Bariri Reservoir (22º06\'S and 48º45\'W, São Paulo State, Brazil) were evaluated by in situ observations in two different areas: one in the limnetic zone (M1) and other in the littoral zone (M2) in February, April, July and September 1998. The phytoplankton primary productivity was determined by the dissolved oxigen method. The values of net primary productivity of the phytoplankton community in M1 varied from 122 mgO2.m-2.h-1 (April) to 2093 mgO2.m-2.h-1 (July), and M2, varied from 157 (April) to 861 mgO2.m-2.h-1 (February). The community respiration M1, varied from 18 (April) to 376 mgO2.m-2.h-1 (February) and M2, varied from zero (April) to 211 mgO2.m-2.h-1 (February).The lowest primary productivity, obtained in April, coincided with the lowest biomass. Probably, phosphorus was the main limitation of the primary productivity on the others study months. The bloom of Microcystis spp (S strategist) in February M1 and M2 and July M1 was related to water column more stable in these periods. In July M1, April M1 and M2 and September M1 and M2, the R and C strategists predominated, such as Rhodomonas lacustri, Aulacoseira granulata granulata, Chlamydomonas spp, Cryptomonas brasiliensis, Cryptomonas tetrapyrenoidosa, Anabaena spiroides and Anabaena circinalis.
Miranda, Alan Wanderley Albuquerque. „Evolução estrutural das zonas de cisalhamento dúcteis na porção centro-leste do domínio da Zona Transversal na Província Borborema“. Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2912.
Der volle Inhalt der QuelleThe studied area is inserted in the Transversal Domain of Borborema Province. The Paleoproterozoic (Riacian) basement encompasses mainly by metaplutonic rocks from Salgadinho and Cabaceiras Complex. These complexes were individualized according to their compositional, textural and/or geochronological datas. The Paleoproterozoic (Orosirian) metasedimentary rocks were interpreted as components of Sertânia Complex. The Estatherian magmatic event is characterized by syenogranitic orthogneisses of the Carnoió-Caturité Suite and metaplutonic rocks of Metanorthositic Boqueirão Complex. The Neoproterozoic lithostratigraphic units are represented by Cryogenian metasedimentary successions of Complex Surubim and by Early-Ediacaran granodioritic and syenogranitic orthogneisses and of the Sumé Complex and Riacho de Santo Antonio orthogneisses, respectively. The Ediacaran granitic magmatism was characterized by the emplacement of Inácio Pereira and Marinho Plutons. The geochronological data (LA-ICPMS) indicate at least of three tectono-magmatic events. The 2042 + 13Ma and 1996 + 11Ma ages from amphibolites of Cabaceiras Complex were interpreted as the crystallization age of the protolith and metamorphism, respectively. The age of 1638 + 13Ma from the syenogranitic hornblende orthogneiss of Carnoió-Caturité Suite was interpreted as the crystallization age of the protolith, marking an Estatherian anorogenic magmatic event. The age of 550 + 3.1Ma acquired in a porphyritic monzogranite of Marinho Pluton is a record of the last magmatic event in the Late-Ediacaran, associated with the final stage of development of the Coxixola Shear Zone. The structural data allowed the individualization of three deformation phases, individualized as D1, D2 and D3. D1 was responsible for generating a S1 foliation, observed only at the hinge of F2 folds. The D2 event is marked by a thrust regime with transport to NNW, observed from asymmetrical shear bands and drag folds in sections parallel to stretching lineation (L2x). Ductile shear zones of different geometry and kinematics had been developed during the D3 phase. The NE-SW Boa Vista, Carnoió and Congo Shear zones exhibit sinistral kinematic in sections parallel to stretching lineation (L3x). The southern limits of these shear zones are connected with Coxixola Shear Zone. This WSW-ENE shear zone with dextral kinematics crosscut the entire studied area, with an average of 300m thickness of mylonitic rocks. The WNW-ESE Inácio Pereira Shear Zone is situated in the eastern portion of the studied area, shows geometric and kinematic characteristics in agreement with an evolution through an oblique-sinistral transpressive regime. The structural evolution of a system of conjugate ductile shear zones is responsible by anastomosed framework exposed in a map view.
Neves, Leonardo Mitrano. „Fatores estruturadores das assembl?ias de peixes em tr?s distintas zonas (rio, mistura e costeira) do estu?rio do rio Mambucaba, Angra dos Reis- RJ“. Universidade Federal Rural do Rio de Janeiro, 2009. https://tede.ufrrj.br/jspui/handle/jspui/1207.
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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPQ
The estuarine systems influence fish assemblages, throughout their longitudinal gradients and remarkable salinity changes. Such assemblages adapt to different habitat constraints and change in spatial and temporal scales. The aim of this study was to assess the ichthyofauna composition and structure in three zones of the Mambucaba estuary (CZ ? coastal zone; MZ ? mixture zone and RZ ? river zone) and their relationship with environmental variables and habitat characteristics. Systematic fish collections (2 months in each seasons) were performed between October 2007 and August 2008, by using otter trawl at two sites in CZ (C1 e C2), beach seine at three sites in MZ (M1, M2, M3) and mesh trays at two sites in RZ (R1 e R2). At each fish sampling occasion, both surface and depth environmental variables of temperature, salinity, conductivity, turbidity and dissolved oxygen were taken and depth was measured. A total of 14,320 individuals, in 111 species (RZ ? 18; MZ ? 50, and CZ - 66) were collected. Distinct fish assemblages were found for each zone, as indicated by low number of common species (14 - MZ and CZ; 8 - MZ and RZ; and 2 - CZ and RZ), and only one abundant species (> 1% of the total number of fish within the zone) being common in more than one zone (Eucinostomus argenteus in CZ and MZ). Such pattern can be related to high salinity variation in MZ and narrow (20 m) channel width connecting the estuary with the sea, which can limit fish movement (into/out of the estuary). In CZ, the three more abundant species were Paralonchurus brasiliensis, Ctenosciaena gracillicirrhus, Anchoa lyolepis, Larimus breviceps and Stellifer brasiliensis, with large contribution of fish from the Scieanidae family in this zone (18 species). Spatial changes inf fish species were not consistent in CZ, probably due to lack of spatio-temporal estuarine plume influence on depth environmental variables (ANOVA, p>0.05). Depth was the main factor to influence spatial changes for Diapterus rhombeus (negative association) more abundant in C1 (average depth = 10 m; ANOVA, p<0.05) and Micropogonias furnieri, P. brasiliensis and Pellona harroweri (positive association) more abundant in C2 (average depth = 17 m; ANOVA, p<0.00). Diapterus rhombeus and Etropus crossotus occured mainly in Spring and Summer, and Eucinosomus gula in Spring. The most abundant species in CZ, typical of high salinty influence, is a indication that this zone have characteristics to inner continental shelf. In MZ, most abundant species (Eugerres brasilianus, Eucinostomus melanopterus, Trinectes paulistanus, Gobionellus shufeldti, G. oceanicus, Geophagus brasiliensis, Centropomus parallelus and Citharichthys arenaceus) have higher number and weight of individuals in M1 (ANOVA, p<0.01), an adjacent lagoon connected to the main channel. In spite of the significant negative correlation between this species and salinity (r-Spearman>0.32, p<0.01), the more sheltered areas in M1 seem to be more important to determine this pattern than salinity itself. The site M1 also have more number of individuals and species (ANOVA, p<0.01), and larger number of fish of smaller size (CT median = 58mm) compared to M2 and M3, located in the main channel (median = 106mm) according to Median and Kruskall-Wallis tests (p<0.01; 2 = 1167.5), indicating the importance of this area for species recruitment. Low average similarity (SIMPER) for sites M2 (38.7%) and M3 (17.8%) indicate larger variability of assemblage in these sites, probably due to lesser habitat structure e higher dynamism. In RZ, the fish assemblage have few species (5) with abundance higher than 1% of the total number of fishes, being dominated by Dormitator maculatus, Astyanax sp and ix Microphis brachyurus lineatus, species typical of upper estuaries and lower river reaches. Spatial variation was detected for D. maculatus only, more abundant at R2, a site with abundant riparian vegetation, mainly grass. Dormitator maculatus was more abundant in Summer and Autumn, M. brachyurus lineatus, in Spring, Autumn and Winter and Astyanax sp was absent in Spring only. Patterns in fish assemblage structure were at large scale, primarily species-specific responses to dominant environmental gradient, while at small scale, results of association with the habitat.
Os sistemas estuarinos influenciam as assembl?ias de peixes, ao longo de seus gradientes longitudinais e das marcadas varia??es da salinidade. Estas assembl?ias se adaptam ?s diferentes condicionantes do habitat e variam em escalas espaciais e temporais. O objetivo do presente estudo foi avaliar a composi??o e estrutura da ictiofauna em tr?s zonas do estu?rio do rio Mambucaba (ZC ? zona costeira; ZM ? zona de mistura e ZR ? zona de rio) e suas rela??es com as vari?veis ambientais e caracter?sticas do habitat destas zonas. Coletas sistem?ticas de peixes (2 meses por esta??o do ano) foram realizadas entre outubro de 2007 e agosto de 2008, com arrastos de fundo em dois locais da ZC (C1 e C2), arrasto de praia em 3 locais da ZM (M1, M2, M3) e peneira em 2 locais da ZR (R1 e R2). Em cada amostragem de peixes, foram tomadas, para a superf?cie e fundo, as vari?veis ambientais de temperatura, salinidade, condutividade, turbidez e oxig?nio dissolvido, bem como medida a profundidade. Um total de 14320 indiv?duos, constitu?dos por 111 esp?cies (ZR ? 18; ZM ? 50 e ZC - 66) foram coletados. Assembl?ias de peixes distintas foram identificadas para cada zona, indicadas pelo baixo n?mero de esp?cies comuns (14 - ZM e ZC; 8 - ZM e ZR; e 2 - ZC e ZR), e com apenas uma esp?cie abundante (> 1% do numero total de peixes na zona) comum em mais de uma zona (Eucinostomus argenteus na ZC e ZM). Tal padr?o pode estar relacionado ? maior variabilidade da salinidade existente na ZM e a estreita (20 m) largura do canal de conex?o com o mar, fatores que podem ser limitantes aos movimentos (entrada/sa?da) de peixes. Na ZC, as tr?s esp?cies mais abundantes foram Paralonchurus brasiliensis, Ctenosciaena gracillicirrhus, Anchoa lyolepis, Larimus breviceps e Stellifer brasiliensis, com a maior participa??o de peixes da fam?lia Sciaenidae nesta zona (18 esp?cies). As varia??es espaciais das esp?cies foram pouco consistentes na ZC, provavelmente relacionado a influencia da pluma estuarina n?o ter provocado mudan?as espa?o-temporais nas vari?veis ambientais de fundo (ANOVA, p>0,05). A profundidade foi o principal fator respons?vel pela separa??o espacial encontrada para Diapterus rhombeus (associa??es negativas) mais abundante em C1 (profundidade m?dia = 10 m; ANOVA, p<0,05) e Micropogonias furnieri, P. brasiliensis e Pellona harroweri (associa??es positivas) mais abundantes em C2 (profundidade m?dia = 17 m; ANOVA, p<0,00). Diapterus rhombeus e Etropus crossotus ocorreram principalmente na primavera e ver?o, e Eucinosomus gula na primavera. As esp?cies mais abundantes da ZC, t?picas de ?guas com maior influencia salina, ? um indicativo de que esta zona tem caracter?sticas mais associadas ? plataforma continental interna. Na ZM, a maioria das esp?cies mais abundantes (Eugerres brasilianus, Eucinostomus melanopterus, Trinectes paulistanus, Gobionellus shufeldti, G. oceanicus, Geophagus brasiliensis, Centropomus parallelus e Citharichthys arenaceus) apresentou maior n?mero e peso de indiv?duos em M1 (ANOVA, p<0,01), uma lagoa adjacente conectada ao canal principal. Apesar das correla??es negativas significativas observadas entre estas esp?cies e a salinidade (r-Spearman>0.32, p<0,01), as ?reas mais abrigadas em M1 parecem ser mais determinantes neste padr?o do que a salinidade em si. O local M1 tamb?m apresentou o maior n?mero de indiv?duos e de esp?cies (ANOVA, p<0,01), com maior n?mero de peixes de menor tamanho (CT mediana = 58mm) do que dos locais M2 e M3, situados no canal principal (mediana = 106mm) de acordo com o Teste das Medianas e Teste de Kruskallvii Wallis (p<0,01; 2 = 1167,5), indicando a import?ncia desta ?rea para o recrutamento das esp?cies. A baixa similaridade m?dia (SIMPER) para os locais M2 (38,7%) e M3 (17,8%) indicam uma maior variabilidade na assembl?ia destes locais, possivelmente devido a menor estrutura??o do habitat e maior dinamismo. Na ZR, a assembl?ia de peixes apresentou poucas esp?cies (5) com abund?ncia maior que 1% do n?mero total de peixes, sendo dominada por Dormitator maculatus, Astyanax sp e Microphis brachyurus lineatus, esp?cies t?picas de ?reas lim?trofes entre a zona superior do estu?rio e a zona baixa de rio. Varia??es espaciais foram detectadas apenas para D. maculatus, mais abundantes em R2, um local com abundante vegeta??o marginal composta principalmente por gram?neas. D. maculatus foi mais abundante no ver?o e outono, M. brachyurus lineatus, na primavera, outono e inverno e Astyanax sp foi ausente somente na primavera. Os padr?es na estrutura da assembl?ia de peixes s?o, em maior escala, primariamente resultado das respostas individuais das esp?cies ao gradiente ambiental dominante, enquanto em menor escala, resultado das associa??es com o habitat.
Barros, Tomás. „Previsão do tempo de vida de fadiga da aeronave Epsilon TB-30 baseada em ensaios experimentais representativos da operação da aeronave em provetes que simulam as zonas críticas“. Master's thesis, Academia da Força Aérea, 2019. http://hdl.handle.net/10400.26/39701.
Der volle Inhalt der QuelleThe objectives of this work are the characterization of the Portuguese Air Force Epsilon TB-30 fleet operation and the fatigue lifetime predicition with the implementation of a Structural Health Monitoring system in this aircraft. The implementation of this system comprised the installation of one accelerometer near the aircraft center of gravity, five strain sensors in five critical locations and a data acquisition unit. Flight data was recorded with this system, allowing the definition of transfer functions that correlate the aircraft acceleration with the strain in the critical locations. The analysis of acceleration flight data from a previous instrumentation, using signal filters and the level cross counting method, allowed the definition of the 1000 flight hours accumulated load spectrum. The objective of characterizing the fleet operation led to the need of establishing a severity comparison with the reference operation considered by the aircraft manufacturer. The methodology used in this work consisted of the accumulated damage calculation and a crack propagation study, for which random load sequences were generated based on the 1000 flight hours accumulated load spectra. The crack propagation study included a numerical approach with the Walker and NASGRO crack propagation models in the AFGROW© software and a finite element model developed in the ABAQUS© software. Additionally, it included an experimental approach with variable amplitude fatigue tests performed in Instituto Superior Técnico. In the scope of the crack propagation study, a 2024-T351 aluminium alloy representative specimen of one of the aircraft critical locations was designed, in which a corner notch was inserted by electrical discharge machining. The results of the present study may contribute to a possible change of the aircraft maintenance program and provide quantitative information about the stresses in the aircraft critical locations to the manufacturer.
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Louati, Sihem. „Acquisition, traitement, analyse, modélisation et inversion des enregistrements de bruit de fond sismique : application : les berges du lac sud de Tunis“. Paris 6, 2013. http://www.theses.fr/2013PA066475.
Der volle Inhalt der QuelleThe analysis and characterization of the sub-soil can be performed using several geophysical methods and surveys. These methods include traditional seismic methods (active or passive) that require the use of natural or artificial seismic sources and whose application is limited by the characteristics of the sources. After the finding of Nakamura theory (1989), a recent passive seismic technique consist to record the ambient seismic noise is established. To analyze the seismic risk of south lake banks of Tunis City, we have used this method. Campaigns measures in the field of study leads to the determination of seismic micro-zoning maps and identification of origin of these signals. Using several numerical simulations, the development of the relationship between a soil column and the results of these ambient seismic noise recordings is achieved. The estimation of the propagation of a seismic source through a column of tabular soil is performed. Then, a distribution of noise sources in both surface and subsurface is made and an estimation of the seismic signal generated by this two-dimensional distribution is performed. Geophysical and geotechnical site characterization study allows the comparison between these results and the results from an inversion of the curves H/V. This comparison reassures outcomes deriving records seismic noise
Sainz-Maza, Aparicio Sergio. „Caracterización gravimétrica de zonas de rift en islas volcánicas oceánicas : aplicación a las islas de Tenerife y el Hierro“. Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/461592.
Der volle Inhalt der QuelleRift systems in oceanic volcanic areas are related to the growth of large volcanic buildings and are defined as areas of the crust subjected to extensive stresses that generate fractures in the form of fissures through which lava is emitted. The groups of cracks delineate rift systems. Traditionally, they have been considered deep structures acting as conduits that connect the areas of magma generation in the mantle with the earth's surface, controlling the magma rise in a way direct. Some recent studies based on geological, geophysical and paleomagnetic data question this deep rooting, considering instead a shallower origin. This origin would be associated with both regional tectonics and local processes related to variations in the gravitational load during the development process of volcanic buildings. In order to increase the knowledge of these systems we have studied the rift systems of Tenerife and El Hierro, both located in the Canarian Archipelago. Both, offer the opportunity to carry out a study of this type in view of its surface characteristics. Morphologically, these islands present three potential zones of rift, also denominated "dorsales". In surface, both islands show a similar arrangement of their basaltic volcanism along these “dorsales”, having traditionally been proposed a triple rift configuration in each island. We built an internal image of the Tenerife and El Hierro rift systems based in 3D models of subsoil density contrasts. These models were obtained by the application of an inversion genetic algorithm based on gravity data which uses as input parameters gravimetric anomalies. These models are the basis on which we will develop the subsequent discussions. The model obtained for the El Hierro Island, the rift systems are poorly rooted structures. They would have a shallower origin. Moreover, the three-dimensional model obtained for the north- western ridge of the island of Tenerife suggests a structure similar to the previous one, a superficial origin of these rift systems. In contrast, the comparison between the models corresponding to the structure under the “dorsal” and the subsurface structure corresponding to the southern part of the island, shows clear differences between the two. This indicates that the origin of both is different and, therefore, the volcanic model of the southern part of the island would be more in correspondence with a monogenetic volcanic field than with a typical configuration of rift, as already had been suggested in previous works.
Cunha, F?bio Souza e. Silva da. „Condicionamento estrutural das zonas de cisalhamento da regi?o de Forquilha, dom?nio Cear? Central: uma abordagem integrada de sensoriamento remoto e geologia estrutural“. Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18341.
Der volle Inhalt der QuelleConselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The studied region, named Forquilha and localized in northwestern Central Cear? domain (northern portion of Borborema Province), presents a lithostratigraphic framework constituted by paleoproterozoic metaplutonics, metasedimentary sequences and neoproterozoic granitoids. The metasedimentary rocks of Cear? group occupy most part of the area. This group is subdivided in two distinct units: Canind? and Independ?ncia. Canind? unit is represented basically by biotite paragneisses and muscovite paragneisses, with minor metabasic rocks (amphibolite lens). Independ?ncia sequence is composed by garnetiferous paragneisses, sillimanite-garnet-quartz-muscovite schists and quartz-muscovite schists, pure or muscovite quartzites and rare marbles. At least three ductile deformation events were recognized in both units of Cear? group, named D1, D2 and D3. The former one is interpreted as related to a low angle tangential tectonics which mass transport is southward. D2 event is marked by the development of close/isoclinal folds with a N-S oriented axis. Refolding patterns generated by F1 and F2 superposition are found in several places. The latest event (D3) corresponds to a transcurrent tectonics, which led to development of mega-folds and several shear zones, under a transpressional regime. The mapped shear zones are Humberto Monte (ZCHM), Po?o Cercado (ZCPC) and Forquilha (ZCF). Digital image processing of enhanced Landsat 7-ETM+ satellite images, combined with field data, demonstrate that these penetrative structures are associated with positive and negative geomorphologic patterns, distributed in linear and curvilinear arrangements with tonal banding, corresponding to the ductile fabric and to crests. Diverse color composites were tested and RGB-531 and RGB-752 provided the best results for lineament analysis of the most prominent shear zones. Spatial filtering techniques (3x3 and 5x5 filters) were also used and the application of Prewitt filters generated the best products. The integrated analysis of morphological and textural aspects from filtered images, variation of tonalities related to the distribution of geologic units in color composites and the superposition over a digital elevation model, contributed to a characterization of the structural framework of the study area. Kinematic compatibility of ZCHM, ZCPC, ZCF shear zones, as well as Sobral-Pedro II (ZCSPII) shear zone, situated to the west of the study area, was one of the goal of this work. Two of these shear zones (ZCHM, ZCPC) display sinistral movements, while the others (ZCSPII, ZCF) exhibit dextral kinematics. 40Ar/39Ar ages obtained in this thesis for ZCSPII and ZCPC, associated with other 40Ar/39Ar data of adjacent areas, indicate that all these shear zones are related to Brasiliano orogeny. The trend of the structures, the opposite shear senses and the similar metamorphic conditions are fitted in a model based on the development of conjugate shear zones in an unconfined transpression area. A WNW-ESE bulk shortening direction is infered. The geometry and kinematic of the studied structures suggest that shortening was largely accommodated by lateral extrusion, with only minor amounts of vertical stretch
A regi?o de Forquilha localiza-se no extremo noroeste do Dom?nio Cear? Central (por??o setentrional da Prov?ncia Borborema) e apresenta um arcabou?o litoestratigr?fico formado por rochas metaplut?nicas paleoproteroz?icas, seq??ncias metasupracrustais e granit?ides neoproteroz?icos. As rochas metassedimentares do Grupo Cear? ocupam a maior parte da ?rea e s?o subdivididas em duas unidades distintas: Canind? e Independ?ncia. A unidade Canind? ? formada basicamente por biotita paragnaisses e muscovita paragnaisses, envolvendo rochas metab?sicas (lentes de anfibolitos). A seq??ncia Independ?ncia abrange paragnaisses granad?feros, intercalados com silimanita-granada-quartzo-muscovita xistos e quartzo-muscovita xistos, quartzitos puros ou com muscovita e, mais raramente, m?rmores. Foram identificados e caracterizados pelo menos tr?s eventos de deforma??o d?ctil, denominados de D1, D2 e D3. O evento D1 pode ser interpretado como correspondente ? uma tect?nica tangencial de baixo ?ngulo com transporte tect?nico para sul. O evento D2 ? caracterizado pelo desenvolvimento de dobras fechadas a isoclinais com eixos aproximadamente N-S. Padr?es de superposi??o de dobras F1 e F2 foram verificadas em diversos locais. O terceiro evento (D3), desenvolvido em um regime transpressional, gerou dobras megasc?picas com eixos NNE a NE e zonas de cisalhamento transcorrentes. Essas zonas transcorrentes D3 s?o denominadas de Zona de Cisalhamento Humberto Monte (ZCHM), Zona de Cisalhamento Po?o Cercado (ZCPC) e Zona de Cisalhamento Forquilha (ZCF). O processamento digital de imagens de sat?lite Landsat 7-ETM+, combinado com dados de campo, demonstrou que essas estruturas penetrativas desenvolveram padr?es geomorfol?gicos positivos e negativos, distribu?dos em arranjos lineares e curvilineares com bandamento tonal, associados ao fabric d?ctil das rochas e a cristas. Diversas composi??es coloridas foram testadas, sendo que RGB-531 e RGB-752 proporcionaram os melhores resultados para an?lise de lineamentos correspondentes ?s principais zonas de cisalhamento. T?cnicas de filtragem espacial (filtros 3x3 e 5x5) tamb?m foram utilizadas, sobressaindo-se os produtos resultantes da aplica??o de filtros Prewitt na banda PC1. A an?lise integrada dos aspectos morfol?gicos e texturais presentes nas imagens filtradas, somados ?s varia??es de cores assumidas pelas unidades geol?gicas nas composi??es coloridas e ? sobreposi??o sobre um modelo digital de eleva??o, permitiram uma caracteriza??o em mega-escala da conforma??o estrutural da ?rea de estudo. Um dos objetivos desse trabalho foi compatibilizar a cinem?tica das zonas de cisalhamento ZCHM, ZCPC, ZCF, juntamente com a zona de cisalhamento (lineamento) Sobral-Pedro II (ZCSPII), situada na adjac?ncia, a oeste da ?rea estudada. As idades 40Ar/39Ar obtidas nesta tese para a ZCSPII e a ZCPC, associadas com outros dados 40Ar/39Ar de zonas de cisalhamento do Estado do Cear?, s?o indicativas de que todas essas zonas estejam relacionadas ? orog?nese Brasiliana. Al?m disso, a orienta??o geral das estruturas, os sentidos de cisalhamento opostos (sinistral na ZCHM e na ZCPC; dextral na ZCSPII e na ZCF) e as condi??es metam?rficas semelhantes conduziram ? proposta de um modelo evolutivo das zonas de cisalhamento da regi?o de Forquilha a partir do desenvolvimento de zonas de cisalhamento d?cteis conjugadas em uma ?rea de transpress?o n?o-confinada, com uma dire??o geral de encurtamento WNW-ESE. A geometria e a cinem?tica do conjunto de estruturas analisadas sugerem que o encurtamento tenha sido amplamente acomodado por extrus?o lateral, com menores quantidades de estiramento vertical
Rafaranalisoa, Esther. „Donnees nouvelles sur la hibonite (ca a112 o19) de madagascar“. Paris 6, 1988. http://www.theses.fr/1988PA066502.
Der volle Inhalt der QuelleNguyen, Quang Nguyen. „Articulation temporelle des mobilités individuelles et impact CO2 dans les différents espaces résidentiels en France (des citadins vertueux, mais uniquement en semaine?)“. Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST0072/document.
Der volle Inhalt der QuelleMy thesis concern is about knowledge and in depth-understanding of the annual distribution of individual mobility in France (distinguishing daily, weekend and long distance trips) according to the residential locations (by category of urban areas) via the development of an annual CO2 emissions assessment, to address the issue of climate change. After a brief methodological description of the tool, using the dataset of the most recent French National Transport Survey (2007-2008), the paper presents some typical results, declining the distribution of CO2 emissions due to this mobility according to the zone of residence: beyond the initial descriptive analyses, a cluster analysis of mobility behavior results in four profiles of mobility according to the CO2-emissions budgets on these three time segments of mobility. It shows that each type of mobility behavior is not available (nor uniform) in only one type of space. A "cocooning effect" can be detected but it is probably not strong enough to confirm that the citizens of (large) city centers during the weekend necessarily ruin their rather virtuous behavior on week days through the use of less polluting modes. Case studies by gender, frequent travelers (pendulous or transcontinental), and some travel purposes (e.g. shopping, leisure) provide additional results. Finally, the analysis of occupancy rates of the car for local travel shows, that more passengers in a vehicle is an important factor for its energy efficiency (and therefore CO2) due to mobility
Nguyen, Quang Nguyen. „Articulation temporelle des mobilités individuelles et impact CO2 dans les différents espaces résidentiels en France (des citadins vertueux, mais uniquement en semaine?)“. Electronic Thesis or Diss., Paris Est, 2014. http://www.theses.fr/2014PEST0072.
Der volle Inhalt der QuelleMy thesis concern is about knowledge and in depth-understanding of the annual distribution of individual mobility in France (distinguishing daily, weekend and long distance trips) according to the residential locations (by category of urban areas) via the development of an annual CO2 emissions assessment, to address the issue of climate change. After a brief methodological description of the tool, using the dataset of the most recent French National Transport Survey (2007-2008), the paper presents some typical results, declining the distribution of CO2 emissions due to this mobility according to the zone of residence: beyond the initial descriptive analyses, a cluster analysis of mobility behavior results in four profiles of mobility according to the CO2-emissions budgets on these three time segments of mobility. It shows that each type of mobility behavior is not available (nor uniform) in only one type of space. A "cocooning effect" can be detected but it is probably not strong enough to confirm that the citizens of (large) city centers during the weekend necessarily ruin their rather virtuous behavior on week days through the use of less polluting modes. Case studies by gender, frequent travelers (pendulous or transcontinental), and some travel purposes (e.g. shopping, leisure) provide additional results. Finally, the analysis of occupancy rates of the car for local travel shows, that more passengers in a vehicle is an important factor for its energy efficiency (and therefore CO2) due to mobility
Senterre, Bruno. „Recherches méthodologiques pour la typologie de la végétation et la phytogéographie des forêts denses d'Afrique tropicale“. Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210954.
Der volle Inhalt der QuelleII. Field data consisted in phytosociological homogeneous sample plots localized within different recognized phytogeographical entities, in a region of tropical Africa where these entities are known to be well conserved. A total of 37 such plots were inventoried in the region extending from the littoral forests of Ndoté, Equatorial Guinea, which are wet evergreen forests, to the continental forests of the Dja, Cameroon, known as evergreen seasonal forests. The studied region also included the oriental Atlantic forests of Equatorial Guinea, known as moist evergreen forests or caesalp forests. In various parts of this continentality gradient, some plots were localized within climax non-zonal formations, namely the submontane rain forests. The emphasis was put on the vegetation of the Monte Alén National Park.
The sampling methodology was willing to be as "complete ", including all strata, "quantitative ", enumerating all individuals, and "representative ", within each stratum, as possible. These multi-layers plots were realised using nested sub-plots, with a sampling size of 100 individuals for every ligneous stratum recognized (dominant trees, dominated trees and shrubs) and a sampling size of 200m² for the herbaceous and suffrutex stratum.
Forest types were defined independently for each stratum and the differences were analysed. A method was proposed for the simultaneous analysis of all floristic data, converting and standardizing the values from ligneous strata, on the one hand, and from understorey strata, on the other hand.
III. Ten forest types were described using IndVal and discussed in the general context of the guineo-congolian region, from a syntaxonomic view point (agglomerative classification) and from a phytogeographical view point (divisive classification). Homologies between these two approaches are described. The proposed phytogeographical system is based on an "open " conception of hierarchical classifications, combining advantages of agglomerative and divisive classifications. In concrete terms, the non-zonal criteria, for example the submontane variants, are categorised separately and in analogy with the zonal criteria, related to the usual phytochoria.
Analysis of ecological relationships for the 10 communities showed that the main variables related to the floristic variability in our mainland rain forests are elevation, rainfall, hygrometry (estimated using bryophytes cover levels) and distance to the ocean. The two extremes on the vertical microclimatic gradient, dominant trees stratum and herbaceous stratum, give similar typologies, however canonical analysis showed that for the herbaceous layer, non-zonal variables (hygrometry and elevation) were gaining more importance when the influence of the two zonal variables was attenuated. In every case, spatial autocorrelation was less important than the environment in explaining floristic variability but its role increased in the spatial arrangement of understorey species, whose dispersal capacity is generally lower than canopy trees. The phytosociological, phytogeographical and ecological description of forest types is accompanied by a physiognomical description using biological types spectrum, as well as architectural models, leaf sizes, etc.
With regard to diversity, we have demonstrated that species richness was higher from upper to lower strata because of the accumulation in lower strata of species from various strata. On the other hand, the proper stratum diversity, i.e. the structural set, decreased from dominant trees to shrubs. The proper diversity of the herb layer showed relatively high figures mainly due to the higher individual density in relation to the existence of microstrata. Within the 37 sample plots, 1,050 taxa have been identified to species or morpho-species levels, for a total of 25,750 individuals. These taxa represent 442 genus among 104 families. The richest forest type is found on the foothills of the Niefang range, on the windward side. This forest type is also characterised by a high number of oligotypic genus and by species belonging to functional types indicators of glacial refuges. These functional types are defined on the basis of the dispersal capacity and on kind of stand needed for effective germination. We formulated the hypothesis that this kind of "foothills refuge ", characterised by his zonal nature, could have been one of the rare refuges for species from mainland rain forests, while montane and fluvial refuges would mainly have preserved species from non-zonal forest types: (sub)montane and riverine.
Based on indicator species of submontane forests, a potential distribution map of this forest type has been realised at the Atlantic central African scale. More than 400 submontane forest localities have been mapped. These forests begin at 400m of altitude near the ocean, and progressively at higher altitude for increasing distance to the ocean. Many lowland localities also comprised submontane species, which could indicate the existence of ecological transgressions. These transgressions would allow migratory tracks for submontane species between isolated mountain ranges, not only during glacial periods, through heights at the northern and southern borders of the congo basin, but also contemporarily through the lowland riverine forest network, in the centre of this basin. Finally, a special attention has been attributed to littoral forests and to some cases of choroecological transgressions, coupled to the ecological equalization phenomenon.
Doctorat en sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
Cheng, Wu-Shiung, und 鄭武雄. „Optical Design and Development for the Ringed Zonal V-cut Structure of the Light Guide Plate“. Thesis, 2008. http://ndltd.ncl.edu.tw/handle/33138343474901883517.
Der volle Inhalt der Quelle國立中興大學
精密工程學系所
96
Most of the small and middle sizes of BLM (backlight module) are using edge-emitting way and it consists of a guide light plate and several pieces of optical films. Other films are utilized to make the luminance and uniformity of the front view angle higher and better. By analyzing the simulation results, we find this new type of light guide plate structure can use less optical films and still has good performance. We also show that this structure can be fabricated and it is believed this technology should be important to the development of thin light guide plate.
Pinto, Daniel Frias de Barros Lopes 1986. „Relationships between the structure of sublitoral assemblages and habitat complexity in a rocky shore in the Portugal coast“. Master's thesis, 2011. http://hdl.handle.net/10451/6584.
Der volle Inhalt der QuelleAs zonas marinhas costeiras são áreas com um elevado interesse ecológico e biológico, desempenhando diversas funções, algumas das quais de extrema importância para a população Humana, como económicas ou de lazer. Ao longo da história da humanidade que se têm presenciado inúmeras migrações para estas zonas, bem como a criação de grandes aglomerados populacionais. Nas últimas décadas têm-se vindo a verificar um aumento das pressões antropogénicas nestas zonas, as quais têm contribuindo para a sua degradação ambiental e por sua vez, comprometendo as suas funções ecológicas e de funcionamento. Entre as comunidades biológicas presentes nas zonas costeiras, destacam-se as dos invertebrados bentónicos. Estes organismos encontram-se na base das cadeias tróficas das comunidades, revelando-se assim de elevada importância ecológica. Estas espécies são também utilizadas como indicadores da qualidade ecológica da água devido algumas características particulares como sua baixa mobilidade, o seu curto ciclo de vida e a sua elevada sensibilidade a perturbações, fazendo desta forma que seja uma possibilidade viável para a monitorização da qualidade da água, e levando inclusive que estes organismos sejam inseridos em diversas metodologias científicas. As comunidades de invertebrados bentónicos são influenciadas por diversos factores, tais como a temperatura, exposição ao hidrodinâmismo e a complexidade topográfica do habitat. A maior complexidade do habitat parece estar relacionada com uma maior abundância e diversidade de taxa. Segundo alguns autores, algumas das razões que podem levar a uma maior abundância, podem estar relacionados com a maior disponibilidade de substrato, a protecção do hidrodinâmismo ou de potenciais predadores. A sazonalidade também é um factor modelador das comunidades bentónicas, no sentido em quanto mais severas as condições, neste caso fruto das estações do ano e suas características climatéricas (menor luminosidade e temperatura e um aumento da turbidez e turbulência), menor vai ser o sucesso das comunidades bentónicas teoricamente. O conhecimento científico existente para a costa portuguesa sobre as comunidades bentónicas de habitat rochoso é escasso, em particular no que se refere à relação a diversidade de taxa e a complexidade do habitat. O presente trabalho teve como principal objectivo comparar as comunidades bentónicas de habitats rochosos com dois níveis de complexidade topográficas diferentes, em duas épocas do ano (Verão e Outono), com o propósito de verificar se a diferentes abundâncias e diversidade nos dois tipos de habitat se verificam independentemente ou não da sazonalidade e tentar compreender melhor estes factores modeladores das comunidades bentónicas. O estudo decorreu na costa marinha do Concelho de Cascais, em dois locais: Avencas, onde o substrato apresenta uma baixa complexidade estrutural, e na Guia, correspondendo a um substrato de elevada complexidade estrutural. As comunidades bentónicas foram amostradas através de duas abordagens distintas: com recurso a raspagens e a censos visuais, ambas realizadas em mergulho com escafandro autónomo. As raspagens foram efectuadas em unidades de substrato com 20 cm x 30 cm, tendo-se conservado o material recolhido em formol a 4% e crivado a 500μ, sendo posteriormente identificados em laboratório através de guias de identificação apropriados. Os censos visuais foram realizados com recurso a um quadrado de 50 cm x 50 cm, com 49 intersecções, equitativamente espaçadas, tendo-se registado cada espécie que coincidisse com os pontos de intersecção. A amostragem ocorreu em duas estações do ano, com a recolha de 24 replicados no mês de Agosto e 24 replicados no mês de Novembro, sendo 12 de uma zona topograficamente simples e 12 de uma topograficamente complexa. No total foram amostrados 27562 indivíduos e 188 espécies através da metodologia das raspagens, e um total de 3025 indivíduos e 30 espécies através da metodologia dos censos visuais. Os resultados obtidos indicaram que as duas metodologias providenciam informação relativa a diferentes escalas espaciais, que afectam os padrões de distribuição e abundância das comunidades bentónicas. As diferentes escalas verificadas ficaram a dever-se principalmente a características de mobilidade e tamanho dos indivíduos. A PERMANOVA evidenciou a sazonalidade como factor estruturante. O efeito da complexidade do habitat só se revelou significativo quando em interacção com a sazonalidade. Foi igualmente possível identificar padrões de variação sazonal da abundância das espécies mais representativas em função da complexidade do habitat na análise SIMPER e na ordenação por escalamento multidimensional (MDS). No geral, verificou-se uma maior abundância no Verão e nos habitats de maior complexidade. No Outono, verificou-se que as associações de habitats de maior complexidade apresentaram maior homogeneidade. As diferenças de homogeneidade do verão para o inverno, possivelmente ficaram a dever-se ao facto de o verão coincidir tipicamente com a altura recrutamento. Uma vez que a maioria os organismos bentónicos apresentam normalmente uma estratégia de vida tipo r, ou seja apresentam um elevado número de indivíduos durante o recrutamento, mas também sofrem uma elevada mortalidade, possivelmente esta estratégia foi umas das causas que levou a verificar-se uma maior abundância e diversidade no verão e um visível decréscimo desta no inverno. No inverno o decréscimo da abundância e da biodiversidade foi mais visível nas zonas de habitat simples do que nas zonas de habitat complexo, possivelmente devido à protecção que estes oferecem dos factores bióticos e abióticos ao contrário das zonas de habitat simples. Também foi possível verificar que as comunidades formadas por organismos bentónicos livres (recolhidos através de raspagens) apresentam uma variabilidade em relação ao habitat e à sazonalidade muito mais evidente que os organismos bentónicos fixos ao substrato (recolhido através do método dos censos visuais) onde os padrões não são tão evidentes, e quer o número de espécies, quer de abundância se mantêm mais uniformes ao longo da amostragem. Verificou-se igualmente a existência de padrões entre os taxas amostrados, onde algumas espécies foram mais abundantes dependendo de características da complexidade do habitat ou da sazonalidade. Os taxas Hiatella artica (Linnaeus, 1767), Alvania sp. (Risso, 1826), Tapes rhomboids (Pennant, 1777) e Ulva lactuca (Linnaeus, 1753) apresentaram maior abundância no Verão, enquanto que Spirobranchus lamarckii (Quatrefages, 1866), Musculus sp. (Röding, 1798), Ciocalypta penicillus (Bowerbank, 1862), Litophylum incrustans (Philippi, 1837) e Coralina enlogata (J. Ellis & Solander, 1786) registaram maior abundância no Outono. Relativamente à complexidade do habitat, os taxa Hiatella artica, Alvania sp., Coralina enlogata, Spirobranchus lamarcky, Litophylum incrustans, e Nereididae apresentaram valores de abundância mais elevados nas zonas de habitat com maior complexidade, enquanto que nas zonas de habitat simples, as espécies melhor representadas foram Ulva lactuca, Musculus sp. e Ciocalypta penicillus. Através deste trabalho, foi possível ver que nestas condições a sazonalidade pareceu ter uma maior preponderância em relação às abundâncias relativas à complexidade do habitat. Uma das razões que pode ter contribuído para este padrão foi o facto de as áreas amostragens não terem dimensão suficiente para que não sejam influenciadas pela migração de outras áreas com características diferentes. Verificou-se igualmente que certas espécies são mais características quer do habitat complexo, quer do habitat simples. Como indicações para o futuro, seria importante a continuidade deste estudo, de forma a englobar as restantes épocas do ano e a verificar se a variabilidade interanual é muito marcada. A incorporação das associações de invertebrados bentónicos em planos de monitorização é particularmente útil, inclusive num contexto de avaliação da qualidade ecológica das águas costeiras. Quanto maior o conhecimento das comunidades bentónicas e seus padrões, melhor e mais adequada resposta pode vir a ser dada para a preservação destas comunidades e consequentemente dos ecossistemas que delas dependem.
The benthic communities are influenced by different natural factors, such as habitat complexity and seasonality. Some authors describe that, the more complex the habitat, the higher the abundance and biodiversity by the taxa, and for the seasonal influence, generally the colder seasons are associated to a lower abundance and biodiversity by the taxa. The main objective of this present work was to evaluate the relation between the diversity and abundance of the benthic community in two different types of rocky habitat (of high and low topographic complexity) in the coastal zone of Cascais, and if the patterns were consistent independently from the season (summer and autumn). The sampling as conducted in Avencas (low complex habitats) and in Guia (high complex habitats), using SCUBA diving procedures and the methodologies of: biomass collection (21cmx30cm) and intersection points in a quadrate of 50x50cm, with equal grid space (49 intersections). The results showed that the seasonality, when compared with the habitat complexity appeared to have a higher influence in the benthic communities. The habitat complexity only was significant when associated with the seasonality. The majority of the taxonomical groups showed higher abundances in summer and in the high complex habitats. The results also showed that the two methods revealed information concerning two different spatial scales. We saw that in the biomass collection method, the main taxa sampled were the Bivalvia, Gastropoda, Malacostraca and Polychaeta. As for the main taxa sampled by the intersection point method, were Demospongiae, Florideophyceae and Ulvophyceae. In general the majority of the species were more abundant in the complex habitats, but in most of the cases the differences weren’t as large as expected. As for the seasonality factor, it didn’t seem to have global tendency.
Côté, Pascal. „Évaluation à long terme de l'impact de différents scénarios de l'approche triade sur la structure des classes d'âge, les patrons de paysage et la récolte de la matière ligneuse en forêt boréale mixte“. Mémoire, 2007. http://www.archipel.uqam.ca/739/1/M10007.pdf.
Der volle Inhalt der QuellePereira, Pedro Daniel Pinto Taveira. „Dimensionamento ao fogo de pavilhões industriais e comerciais em estruturas metálicas com o cenário de incêndio natural“. Master's thesis, 2021. http://hdl.handle.net/10316/98071.
Der volle Inhalt der QuelleUma das grandes limitações na utilização de estrutura metálica em pavilhões de grandes dimensões é o cumprimento dos tempos de resistência ao fogo regulamentares. O método convencional de proteção ao fogo nestas estruturas metálicas é a aplicação de tintas intumescentes, uma vez que é o mais prático de aplicar e o que oferece uma solução esteticamente agradável. Essa solução implica um investimento avultado, podendo em alguns casos anular a competitividade que as estruturas metálicas oferecem. Para o dimensionamento de uma estrutura em situação de incêndio, os programas de cálculo existentes recorrem essencialmente à curva de incêndio padrão ISO 834, que não é adequada a grandes compartimentos, como espaços comerciais e industriais. Estas simplificações de cálculo conduzem a cenários de incêndio potencialmente irrealistas, não garantindo uma segurança proporcional ao capital investido. O presente trabalho apresenta uma avaliação das metodologias de dimensionamento de estruturas metálicas em situação de incêndio de forma a permitir uma redução de custos. Pretende-se obter através de estudos numéricos, curvas mais próximas do desenvolvimento real da evolução da temperatura ao longo do tempo de incêndio, otimizando-se assim a proteção ao fogo a aplicar na estrutura.Realizaram-se dois tipos de avaliações: numa primeira fase recorreu-se a modelos de duas zonas, simulando vários cenários de densidade de carga de incêndio e condições de ventilação. Numa 2ª fase, os cenários mais gravosos foram igualmente simulados através de modelos de dinâmica de fluidos e foram comparados e discutidos os resultados de ambos.No final do documento, são apresentadas as conclusões mais relevantes, entre elas a não necessidade de proteção adicional contra o fogo dos elementos analisados. São ainda indicadas algumas linhas de desenvolvimento futuro no aprofundamento do tema.
One of the major limitations associated with steel structures in large compartments is compliance with the regulatory time of fire resistance. The conventional method of fire protection is the application of intumescent paint since it is the most practical method and the one that offers an aesthetically pleasing solution. This solution implies a large investment, and in some cases, it can reduce the competitiveness of steel structures.The existing calculation software for the design of a structure in a fire situation essentially uses the standard ISO 834 curve, which is not suitable for large rooms, such as commercial and industrial buildings. These calculation simplifications lead to potentially unrealistic fire scenarios, not guaranteeing safety proportional to the invested capital.The present work focuses on the evaluation of the design methodologies of steel structures in a fire situation, in order to allow a cost reduction. It is intended to obtain, through numerical studies, curves closer to the real development of temperature, thus optimizing the fire protection to be applied to the structure.Two types of evaluations were made in a first phase, two zone models were used, simulating various fire load density scenarios and ventilation conditions. In a second phase, the most serious scenarios were also simulated using fluid dynamics models and the results of both were compared and discussed.Finally, the most relevant conclusions are drawn and some lines of future development are indicated.
Pereira, Pedro Daniel Pinto Taveira. „Dimensionamento ao fogo de pavilhões industriais e comerciais em estruturas metálicas com o cenário de incêndio natural"“. Master's thesis, 2021. http://hdl.handle.net/10316/96097.
Der volle Inhalt der QuelleUma das grandes limitações na utilização de estrutura metálica em pavilhões de grandes dimensões é o cumprimento dos tempos de resistência ao fogo regulamentares. O método convencional de proteção ao fogo nestas estruturas metálicas é a aplicação de tintas intumescentes, uma vez que é o mais prático de aplicar e o que oferece uma solução esteticamente agradável. Essa solução implica um investimento avultado, podendo em alguns casos anular a competitividade que as estruturas metálicas oferecem. Para o dimensionamento de uma estrutura em situação de incêndio, os programas de cálculo existentes recorrem essencialmente à curva de incêndio padrão ISO 834, que não é adequada a grandes compartimentos, como espaços comerciais e industriais. Estas simplificações de cálculo conduzem a cenários de incêndio potencialmente irrealistas, não garantindo uma segurança proporcional ao capital investido. O presente trabalho apresenta uma avaliação das metodologias de dimensionamento de estruturas metálicas em situação de incêndio de forma a permitir uma redução de custos. Pretende-se obter através de estudos numéricos, curvas mais próximas do desenvolvimento real da evolução da temperatura ao longo do tempo de incêndio, otimizando-se assim a proteção ao fogo a aplicar na estrutura.Realizaram-se dois tipos de avaliações: numa primeira fase recorreu-se a modelos de duas zonas, simulando vários cenários de densidade de carga de incêndio e condições de ventilação. Numa 2ª fase, os cenários mais gravosos foram igualmente simulados através de modelos de dinâmica de fluidos e foram comparados e discutidos os resultados de ambos.No final do documento, são apresentadas as conclusões mais relevantes, entre elas a não necessidade de proteção adicional contra o fogo dos elementos analisados. São ainda indicadas algumas linhas de desenvolvimento futuro no aprofundamento do tema.
One of the major limitations associated with steel structures in large compartments is compliance with the regulatory time of fire resistance. The conventional method of fire protection is the application of intumescent paint since it is the most practical method and the one that offers an aesthetically pleasing solution. This solution implies a large investment, and in some cases, it can reduce the competitiveness of steel structures.The existing calculation software for the design of a structure in a fire situation essentially uses the standard ISO 834 curve, which is not suitable for large rooms, such as commercial and industrial buildings. These calculation simplifications lead to potentially unrealistic fire scenarios, not guaranteeing safety proportional to the invested capital.The present work focuses on the evaluation of the design methodologies of steel structures in a fire situation, in order to allow a cost reduction. It is intended to obtain, through numerical studies, curves closer to the real development of temperature, thus optimizing the fire protection to be applied to the structure.Two types of evaluations were made in a first phase, two zone models were used, simulating various fire load density scenarios and ventilation conditions. In a second phase, the most serious scenarios were also simulated using fluid dynamics models and the results of both were compared and discussed.Finally, the most relevant conclusions are drawn and some lines of future development are indicated.
Lee, JaeYoung. „Development of Traffic Safety Zones and Integrating Macroscopic and Microscopic Safety Data Analytics for Novel Hot Zone Identification“. Doctoral diss., 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6127.
Der volle Inhalt der QuellePh.D.
Doctorate
Civil, Environmental and Construction Engineering
Engineering and Computer Science
Civil Engineering