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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Elliptic theory on manifolds with nonisolated singularities : IV. Obstructions to elliptic problems on manifolds with edges

Nazaikinskii, Vladimir, Savin, Anton, Schulze, Bert-Wolfgang, Sternin, Boris January 2002 (has links)
The obstruction to the existence of Fredholm problems for elliptic differentail operators on manifolds with edges is a topological invariant of the operator. We give an explicit general formula for this invariant. As an application we compute this obstruction for geometric operators.
52

Dynamic control of aerodynamic forces on a moving platform using active flow control

Brzozowski, Daniel Paul 15 November 2011 (has links)
The unsteady interaction between trailing edge aerodynamic flow control and airfoil motion in pitch and plunge is investigated in wind tunnel experiments using a two degree-of-freedom traverse which enables application of time-dependent external torque and forces by servo motors. The global aerodynamic forces and moments are regulated by controlling vorticity generation and accumulation near the trailing edge of the airfoil using hybrid synthetic jet actuators. The dynamic coupling between the actuation and the time-dependent flow field is characterized using simultaneous force and particle image velocimetry (PIV) measurements that are taken phase-locked to the commanded actuation waveform. The effect of the unsteady motion on the model-embedded flow control is assessed in both trajectory tracking and disturbance rejection maneuvers. The time-varying aerodynamic lift and pitching moment are estimated from a PIV wake survey using a reduced order model based on classical unsteady aerodynamic theory. These measurements suggest that the entire flow over the airfoil readjusts within 2-3 convective time scales, which is about two orders of magnitude shorter than the characteristic time associated with the controlled maneuver of the wind tunnel model. This illustrates that flow-control actuation can be typically effected on time scales that are commensurate with the flow's convective time scale, and that the maneuver response is primarily limited by the inertia of the platform.
53

Analýza variačních metod pro segmentaci digitálního obrazu / Variational methods for segmentation of digital images

Kotera, Jan January 2011 (has links)
The text covers the theory of the Mumford and Shah model for digital image segmentation. The strong and weak formulation is presented and the questions of existence, uniqueness, and solution regularity is answered. Then, a particular variant of the model called `active contours without edges' is numerically implemented. This implementation is tested on several images, the results are presented in detail and theoretically explained.
54

Manejo de lianas em bordas de floresta estacional semidecidual e de cerradão, Santa Rita do Passa Quatro, SP / Management of lianas in semideciduous forest and cerradão edges, Santa Rita do Passa Quatro, SP

Sônia Maria Schaefer Jordão 03 February 2010 (has links)
No Estado de São Paulo, dentro de uma mesma zona climática, a floresta estacional semidecidual e o cerradão são comumente encontrados dividindo o espaço. Atualmente, essas duas formações encontram-se reduzidas a pequenos fragmentos florestais, em estágio avançado de perturbação. Com a fragmentação da floresta, há um aumento da luminosidade nas bordas dos remanescentes florestais e lianas heliófitas podem aumentar suas populações e competir vigorosamente com as espécies arbustivo-arbóreas. O objetivo desse estudo foi verificar o efeito do manejo das lianas sobre o processo de restauração florestal em bordas perturbadas de floresta estacional semidecidual e de cerradão. Também foi analisada a influência do tipo de vizinhança sobre a borda florestal e sobre os resultados do manejo. O experimento foi instalado na região de Santa Rita do Passa Quatro, SP, em bordas de floresta estacional semidecidual, com vizinhanças de cana-de-açúcar e rodovia e em bordas de cerradão, com vizinhanças de eucalipto, cana-deaçúcar e rodovia. O delineamento experimental foi de blocos casualizados, com parcelas de 100m2 e 3 repetições. Nas bordas de floresta estacional semidecidual foram testadas 3 técnicas de manejo: corte de lianas (C), corte de lianas + revolvimento do solo (CR) e corte de lianas + plantio de espécies arbóreas nativas (CP). Nas bordas de cerradão foram testadas 2 técnicas de manejo: corte de lianas (C) e corte de lianas + revolvimento do solo (CR). Para análise do processo de restauração florestal, foram avaliados o crescimento médio em altura e diâmetro das espécies arbustivoarbóreas, a mortalidade média e o número médio de indivíduos ingressantes no estrato arbustivoarbóreo, a chuva de sementes e a mortalidade média e o número médio de indivíduos ingressantes no estrato da regeneração. Nas duas formações florestais, verificou-se uma diminuição na riqueza de espécies arbustivo-arbóreas e no número de árvores de maior porte, no sentido das bordas com vizinhança de eucalipto, para as bordas com vizinhanças de cana-de-açúcar e rodovia, respectivamente. Tanto nas bordas de floresta estacional semidecidual, quanto de cerradão, os resultados do manejo das lianas foram influenciados pelo grau de infestação por lianas, pela estrutura da vegetação recém manejada, pelas espécies presentes e pela vizinhança do fragmento florestal. Embora na maioria dos casos as diferenças não tenham sido significativas, efeitos positivos do corte das lianas foram observados para o crescimento médio em altura ou diâmetro dos indivíduos, principalmente nas áreas mais infestadas. No entanto, nas bordas com vizinhança de rodovia, o corte das lianas pode intensificar os efeitos de borda, a ponto de prejudicar o ingresso das espécies arbustivo-arbóreas no estrato da regeneração. Nas bordas de floresta estacional semidecidual, o corte das lianas não será suficiente para promover a recuperação da fisionomia florestal, pois os indivíduos presentes sob as lianas correspondem a espécies de subbosque, sendo necessário o enriquecimento das bordas com espécies de dossel. Nas duas formações florestais, o revolvimento superficial do solo não favoreceu a regeneração das espécies arbustivo-arbóreas. / In São Paulo state, throughout the same climatic zone, semideciduous forests and cerradão patches commonly share the same geographic area. Currently, these two formations are reduced to small fragments, in advanced stage of disturbance. Along with the fragmentation of the forest, there is an increase in ligth incidence at the edges and lianas generally increase their populations, competing vigorously with trees and shrubs species. The objective of this study was to verify the effect of management of lianas on the processe of restoration of forest physionomy in disturbed edges of semideciduous forest and cerradão. It was also analyzed the influence of matrix on the edge of forests and the results of liana removal management. The experiment was installed in Santa Rita do Passa Quatro, SP, on the edges of semideciduous forest fragments surrounded by sugar cane and roads, and cerradão fragments bordered by eucalyptus plantations, sugar cane and roads. The experimental design was randomized with blocks of plots of 100m2 and 3 replications. At the edges of semideciduous forest three techniques of management were tested: cutting of lianas (C), cutting of lianas + revolving surface soil (CR) and cutting of lianas + planting of native tree species (CP). On the edges of cerradão two management alternatives were tested: cutting of lianas (C) and cutting of lianas + revolving surface soil (CR). To analyze the process of restoration of forest physionomy, we assessed the average growth in height and diameter of tree and shrub species, the average mortality and average number of individuals entering the tree stratum, the rain seed, the average mortality and the average number of individuals entering the stratum of regeneration. In both forests, there was a decrease in the richness of tree and shrub species and the number of larger trees from areas surrounded by eucalyptus to areas in a matrix of sugar cane and road. The results of lianas management, both on semideciduous forest and cerradão, were influenced by the degree of infestation, by the structure of vegetation recently managed, by the species composition and by the nature of surrounding matrix. Although in most cases the differences were not significant, positive effects of cutting lianas were observed on the average growth in height or diameter of the individual, mainly in the most infested areas. However, when the edges are contiguous to roads, lianas removal may intensify edge effects, as to disturb the number of individuals entering the stratum of regeneration. On semideciduous forests, cutting the lianas on the edges alone will not be enough to promote the recovery of the forest structure, because individuals providing support for lianas are understory species, being necessary the enrichment of the edges with the tree canopy species. In both forests, the revolving surface soil did not favor the regeneration of arbustive-arboreal species.
55

Urbanização de fronteira: práticas de apropriação do espaço nas regiões mais pobres da cidade de São Paulo. O caso dos assentamentos Jardim Pernambuco e Nova Vitória / Urbanization at the city edges: practices of appropriation of space in the poorest regions of the city of São Paulo. Case study of the settlements of Jardim Pernambuco and Nova Vitória.

Francisco Luiz Scagliusi 22 February 2013 (has links)
A tese desenvolvida neste trabalho trata de formas específicas de produção do espaço nas regiões de fronteira urbana. Investiga o caso de dois assentamentos clandestinos localizados no extremo da zona leste da cidade de São Paulo. Nossa hipótese identifica o início da década de 80 como um ponto de inflexão na dinâmica espacial da cidade, provocada por novos marcos regulatórios e pela ação de movimentos de luta por moradia. significa ainda uma tentativa de nomear processos e práticas relacionadas a formas específicas de apropriação do espaço, diferenciando do conceito de periferia, que não mais compreende a dinâmica espacial sócio-espacial da cidade nestas regiões. / This tesis deals with specific forms of the prodution of space at the edges of the city. It investigates the case of two illegal settlements located 22km from the city centre, at east zone. Our hypothesis sees the early 80\'s as a turning point in the spacial dynamics of the city, caused firstly by the introduction of new reglatory framework and secondly, by the rise of organized land occupation movements for housing. A central question is the attempt to nominate a set of processes and practices related to specific forms of space appropriation, that differentiate themselves from the ones practiced in the traditional concept of peripheral growth and that no longer follow the old socio-spacial city dinamic in these regions.
56

Effet du paysage sur la structure des communautés fongiques foliaires / Effect of the landscape on foliar fungal community structure

Fort, Thomas 22 November 2016 (has links)
Les feuilles hébergent une grande diversité de micro-organismes. Parmi les facteurs responsables de la structuration des communautés microbiennes foliaires, l’effet du processus de dispersion reste peu étudié. Les structures paysagères telles que les lisières ou l’hétérogénéité du paysage influencent la migration et la dispersion de nombreuses espèces de macro-organismes, mais l’effet de tels facteurs sur la composition des communautés microbiennes foliaires n’a jamais été testé.Nous faisons l’hypothèse que les parcelles forestières sont une source de champignons foliaires pour les vignes adjacentes. Nous avons comparé les communautés fongique foliaires et aériennes de la vigne et des forêts adjacentes au cours d’une saison de végétation, testé l’effet d’une lisière forestière sur ces communautés et évalué l’effet de la composition du paysage sur ces communautés. Les communautés fongiques ont été caractérisées par métabarcoding.Les communautés fongiques foliaires viticoles et forestières divergent au cours de la saison. Ni la distance à la lisière, ni la proportion de forêt dans le paysage n’affectent les communautés foliaires de la vigne, mais les communautés aériennes diffèrent en fonction de la distance à la lisière forestière. Ces résultats suggèrent que la dispersion ne joue qu’un rôle mineur dans la structure des communautés fongiques foliaires. De nombreuses pressions de sélection telles que les pratiques agricoles semblent en revanche avoir un effet fort sur ces communautés. Des études supplémentaires sont nécessaires pour vérifier la contribution relative de ces pressions de sélection, ainsi que le potentiel service de régulation fourni aux cultures par la forêt. / Plant leaves host a large diversity of microorganisms. Among the factors shaping foliar microbial community structure, the effect of the dispersal process remain understudied. Landscape elements, such as edges or landscape heterogenity, influence migration and dispersal of many macro-organism species. However, the effect of such factors on foliar microbial communities has never been studied. We hypothesized that forests are a source of foliar fungi for adjacent vineyards. We compared foliar and airborne fungal communities in vineyard and adjacent forests along a vegetative season, we examined the effect of a forest edge on these communities in a vineyard, and weassessed the effect of landscape composition on these communities. Fungal communities were characterized with a metabarcoding method. Foliar fungal communities in vineyards and forests diverge over the course of the vegetative season. Neither the distance to the edge nor the proportion of forest in the landscape affect foliar fungal communities in vineyards, while airborne communities change with the distance to the forest edge. These results suggest that dispersal is not dominant in shaping foliar fungal communities. Instead, many selective pressures such as agricultural practices seem to shape strongly these communities. Further investigations are required in order to estimate the relative contribution of those processes, and the potential ecosystem service provided by the forest to crops.
57

Moderní metody zvýrazňování statických MR obrazů / Modern Methods of MR Static Image Enhancement

Zbranek, Lukáš January 2009 (has links)
The aim of this masters thesis is design and implement an appropriate method for highlighting MR images and the identification of rough edges to provide for division of controlled areas. To this purpose is possible to use the Wavelet analysis. For the simulation environment I using MATLAB entviroment, where introduce the comparison for different types of de-noising and too for different mother wavelets. These methods will be implemented on various MR images of termoromandibular joint.
58

The Effects of Land Management Edges on the Diversity, Abundance, and Distribution of Small Mammals and Bats

Stoneberg, Kelsey N. 12 August 2020 (has links)
No description available.
59

Droplets, Films and Edges: Studies of the Physical Character of Diblock Copolymers

Croll, Andrew B. January 2008 (has links)
Block copolymers, long chain molecules of two distinct chemical species joined covalently to one another, have long been known to form organized structures on the nanoscopic level. For example, if the two chains are the same length a lamellar structure results . In this work we show how this internal structure causes distinct deviation from 'normal' fluid behavior. We begin with the observation of block copolymer droplets with atomic force microscopy. We note the droplets form nearly conical shapes in stark contrast to the usual spherical cap. These droplets are found t o spread at an incredibly slow speed, and to have interesting instabilities in their wetting layer. We move on to studies of completely wet substrates (i.e. thin films) near the order-disorder transition of the material. Here we directly observe, with optical microscopy, a change in the fundamental spacing of the diblock's internal structure. This represents a superior method of measurement of the Flory-Huggins interaction parameter, which we verify in several ways. We also use the change in lamellar thickness to drive diffusion from one layer to another, and by similar measurements we can determine the kinetics of diffusion between the lamellar layers. In the last study we measure the lamellar edges on a gradient thickness sample with optical microscopy. In so doing we can directly observe surface induced ordering, and for the first time, can precisely resolve the near surface ordering dynamics. / Thesis / Doctor of Philosophy (PhD)
60

Friisgatan - unikum eller ny stadsbyggnadsnorm. En fallstudie om fysiska egenskaper på en stadsgata i Malmö

Vojta, Benjamin, Lindblad, Mattias January 2017 (has links)
En trend inom svensk stadsbyggnad idag är att försöka återskapa stadsdelar med innerstadens karaktär i nybyggnadsområden. Dessa gator konstrueras i många fall inte i närheten av städernas traditionella stadskärnor där de från början uppkom. Det finns en del röster inom ämnet som pratar om hur en stadsgata som gynnar folkliv ska se ut. Friisgatan i Malmö har vid en opinionsundersökning blivit utsedd till stadens hetaste gata. Detta gav oss en bra anledning att använda den som en fallstudie för denna uppsats då den identifierats besitta fysiska egenskaper som lockar människor. Syftet med uppsatsen är att förstå vilka fysiska egenskaper Friisgatan besitter. Vidare är syftet också att skapa kunskap kring hur Friisgatans fysiska egenskaper påverkar användningen av gatan.Metoder som används i fallstudien genomförd i denna uppsats innefattar kartstudier, inventering, passiv observation samt kortare samtalsintervjuer som komplement. Litteratur som behandlar gators fysiska egenskaper har studerats för att kunna förstå de resultat empirin har genererat.Arbetets slutsats är att kontinuerligt folkliv skapas genom ett samspel mellan flera olika fysiska egenskaper. Var gatan är placerad i förhållande till närliggande noder skapar flöden. Dessa flöden stannas upp genom att byggnader och gränssnitt skapar förutsättning för att verksamheter ska finnas. Dessa verksamheter gör anspråk i det offentliga rummet som lockar människor att stanna upp. / A current trend within the Swedish city planning is to try to recreate inner city-like areas on the outskirts of Swedish cities where new neighbourhoods are being built. There are different opinions regarding what a lively city street should look like. Friisgatan in Malmö in south of Sweden is an inner city street that has been previously chosen as the “coolest” street in the city. This provided us with an excellent reason to use this street as a case study for this thesis as the street seems to possess the characteristics of a “people magnet”. The aim of this thesis is to understand what physical features are prevalent on Friisgatan. Further, the aim is to create understanding for how these features affect street life.The methods used in the case study part of this thesis include: map studies, inventory, unstructured observation as well as informal interviews conducted on Friisgatan. We researched literature about physical street features to help us better understand the results the empirical study generated.The conclusion of this thesis is that the continuous street life is created through a range of interconnecting features. The ability of buildings and urban interfaces to house different kinds of businesses is essential, along with the location of the street in relation to nodes, for creating a stable flow of people. Street businesses are able to claim the public space outside of their shops which ultimately results in passers-by becoming part of the continuous street life.

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