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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.
291

Obtenção e caracterização de compósito verde de casca de pinhão e poliuretana derivada do óleo de mamona / Preparation and characterization of pinhão husk and polyurethane derived from castor oil green composite

Protzek, Giuliana Ribeiro 13 December 2017 (has links)
Compósitos verdes são caracterizados por possuir matriz polimérica e reforço derivado de fontes naturais. Polímeros derivados do petróleo não são biodegradáveis e possuem solventes orgânicos na sua composição. Solventes orgânicos são tóxicos e poluentes. A poliuretana derivada do óleo de mamona é derivada de fonte renovável, biodegradável e não possui solventes orgânicos em sua composição. A casca de pinhão é um resíduo do pinhão, semente do pinheiro de Paraná. O objetivo desse trabalho é desenvolver e caracterizar o compósito de casca de pinhão com PU derivada do óleo de mamona. A fibra foi caracterizada quimicamente, por FTIR, TGA e MEV. A PU foi caracterizada por ensaio de resistência à flexão, FTIR e TGA e os compósitos, por testes de densidade, absorção de água, inchamento em espessura, resistência à flexão de três pontos, FTIR e TGA. A superfície da fratura foi avaliada por MEV e a homogeneidade dos compósitos por perfil de densidade e raios-X. O compósito de 35%PU apresentou resistência à flexão de 51,55 MPa, densidade de 1018 kg/m³, absorção de água em 24 horas de 7,95% e inchamento em espessura em 24 horas de 5,36%. O material apresenta propriedades mecânicas apropriadas para uso em mobiliário e artesanato. / Polymeric composites reinforced with natural fibers are denominated green composites. Polymers comes from petroleum source, a non-biodegradable material and has volatile organic compounds, VOC, in its composition. Organic solvent are toxics and pollute the environment. The Polyurethane derived from castor oil is polymer produced from renewable sources, biodegradable material and there are no VOC in its composition. Araucária pine nut shell is a residue from its Araucaria pine seed. The aim of this work is to develop and characterize composites of pine nut shell with polyurethane derived from castor oil. The fiber was chemically characterized, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). PU was characterized by flexural strength, FTIR and TGA and composites was characterizes by density test, water absorption and swelling in thickness, flexural strength, FTIR, TGA. SEM evaluated the fracture surface and X-ray and vertical density profile verified the composites homogeneity. 35%PU composites presented flexural strength of 51,55 MPa, density of 1018 kg/m³, 7,95% of 24h water absorption and 5,36% of 24h swelling in thickness of. The material exhibits properties suitable for use in furniture and handicrafts.
292

Irrigação com efluentes secundários no crescimento, produtividade e concentração de nutrientes no solo e na mamoneira. / Secondary effluent irrigation in the growth, yeld and nutrient concentrations in the soil and in the Ricinus communis L.

SILVA, Manassés Mesquita da. 15 July 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-07-15T21:52:49Z No. of bitstreams: 1 MANASSÉS MESQUITA DA SILVA - TESE PPGEA 2010..pdf: 9882799 bytes, checksum: 238c0fd99ae692419b807452671a0831 (MD5) / Made available in DSpace on 2018-07-15T21:52:49Z (GMT). No. of bitstreams: 1 MANASSÉS MESQUITA DA SILVA - TESE PPGEA 2010..pdf: 9882799 bytes, checksum: 238c0fd99ae692419b807452671a0831 (MD5) Previous issue date: 2010-12 / CNPq / A cultura da mamona, devido à elevada necessidade de água e de nutrientes, possui características ideais para o recebimento, via irrigação, de águas residuárias de esgoto doméstico tratado. A principal vantagem desta prática é a reciclagem de água e nutrientes. Neste contexto, o objetivo deste trabalho foi estudar, por meio de experimento em condições de campo, o efeito de três configurações de tratamento de esgoto doméstico, água de abastecimento e lâminas de irrigação sobre o crescimento, produtividade, estado nutricional da planta e fertilidade do solo ao final do experimento. O delineamento estatístico utilizado foi blocos ao acaso em esquema fatorial 4x2 com quatro repetições. Os fatores de estudo foram quatro tipos de água (Al - Efluente do reator UASB + Lagoa de polimento; A2 - Efluente do Decanto-Digestor + Filtro anaeróbio + Lagoa de estabilização; A3 - Efluente do Filtro anaeróbio + Lagoa de estabilização e A4 - Água de abastecimento) e duas lâminas de irrigação (Ll=100 e L2=120% da Evapotranspiração de cultivo). A água foi aplicada utilizando um sistema de irrigação localizada por gotejamento com irrigações a cada três dias. Avaliaram-se altura de planta, diâmetro caulinar e número de folhas aos 29, 43, 57, 71 e 86 dias após a germinação. Ao final do experimento foram obtidos a produtividade de sementes, fitomassa aérea, estado nutricional das plantas e a fertilidade do solo. Com base nos resultados concluiu-se que as plantas irrigadas com o efluente tratado apresentaram crescimento e produtividade de sementes significativamente iguais, porém superiores às plantas irrigadas com água de abastecimento. O teor de óleo das sementes foi maior para as plantas irrigadas com 120% da ETc. Em relação ao solo, constatou-se que os teores de P, K e Na no solo não diferiram estatisticamente, para as três configurações de tratamento de água residuária. Por meio da análise foliar da mamoneira, constatou-se que, de maneira geral, a planta não sofreu restrições quanto aos teores de P, Ca e Mg. As concentrações de N, K e Na nos tecidos foliares foram significativamente iguais, para as plantas irrigadas com efluente tratado. Os resultados obtidos permitem considerar que é promissor o aproveitamento de efluentes de esgoto doméstico tratado em cultivos agrícolas. / Castor bean cultivation, due to the high water and nutrients consumption, presents the ideal characteristics for receiving wastewater from treated sewage. Economics of fertilizer, recycling of water and nutrients and increased productivity are the main advantages of this practice. The objective of this study was to investigate, under field conditions, the effect of three configurations of domestic wastewater treatment, water supply and water depth on growth, yield, plant nutritional status and fertility of the soil at the end of the experiment. A randomized block design was used, with 4x2 scheme of factorial analysis with four replications, testing four types of water (Al - effluent from the UASB reactor + Polishing Pond; A2 - effluent from the Digester Decant + Anaerobic Filter + Stabilization Pond; A3 - effluent form the Anaerobic Filter + Stabilization Pond; and A4 - Urban water supply) and two water depths (100% and 120% Crops évapotranspiration). Water was applied using a drip irrigation system every three days. Plant height, stem diameter and number of leaves were evaluated at 29, 43, 57, 71 and 86 days after germination. Productivity of seeds, plant nutritional status and soil fertility were evaluated at the end of the experiment. Based on the results no significant difference in growth and seed production when using treated wastewater. Contribution of nutrients through wastewater favored the growth of plants, but was not enough to increase the production in appropriate levels of mineral fertilization and irrigation. For soil fertility, there was no significant difference in levels of P, K and Na for the three configurations of wastewater treatment. In general, there were no restrictions regarding the contents of P, Ca and Mg in the leaf of castor bean. The concentrations of N, K and Na in the leaf tissues were significantly equal for plants irrigated with treated effluent.
293

Hybridní směsi na bázi recyklovaných plastů / Hybrid Blends of Recycled Plastics

Černý, Miroslav January 2017 (has links)
Work describes the relationship between structure and mechanical properties in case of hybrid mixtures. They are composed from polyurethane matrices (eventually polyurethane-urea or polyurethane-inorganic filler mixtures), different rubber fractions as filler and eventually reinforcement made from PET monofilaments. Mechanical behaviour was studied by tensile testing. Studied mechanical properties include tensile modulus, ultimate strength and strain and also specific energy need neccessary for ultimate strength achievement. Prepared materials are naturally porous. Therefore their mechanical behaviour has to be described generally for porous composites. The porosity occurence means, that it is difficult to describe them by models valid for mechanical behaviour (mainly elastic modulus) of nonporous composites. Models are also based on idealized structures on microscopic level. In case of porous composites, it is very difficult to create any idealized structure. The structure is changed with modifications of composition (change of components or their rates). These conditions have lead to utilizing of different approach how to describe the relationship between structure and mentioned mechanical properties. The chosen approach comes from knewledge about structural parametres coming from porosity. Structural parameters describe the structure on macroscopic level. They include interspace volume (volume lying between filler particles), interspace filling (how the matrix fills the interspace volume) and matrix volume fraction. Proposed parameters are used in relations, where they are fitted by exponents to interlay values of chosen mechanical properties for composites containing discrete matrix and filler. Found exponents are then described by properties of matrices to obtain relations describing properties of filled porous materials. Very similar approach was chosen for description in the case of reinforced composites. Proposed relation are potentially valid for materials containing binding matrix, infinity count of fillers and one kind of reinforcement.
294

L’exploitation de la faune par les Iroquoiens : l’alimentation carnée des habitants du site McDonald (BgFo-18)

Chapdelaine, Maude 12 1900 (has links)
This thesis explores patterns of faunal exploitation habits at the McDonald site, in the Saint-Anicet area during the Late Woodland period. The main goal is to determine the importance of wild game in the Iroquoian economical system which is based on the balance of fishing, hunting and horticulture. The result of the faunal analysis shows that White-Tailed Deer, North American Black Bear and North American Beaver are the most important taxa contributing to the subsistence economy of the inhabitants of the site. This was determined by standard zooarchaeological methods, including calculation of the number of identified specimens (NISP), the minimum number of individuals (MNI), meat weight (MW) and ethnohistorical data. This thesis also discusses the spatial distribution of animal skeletal remains, comparing meat consumption patterns within each family unity inside the longhouses and within and between each longhouse. This comparison shows that faunal remains are mostly located in the central alignment of longhouses and are homogeneously distributed. The taxa distributed within the longhouses suggest relatively equalitarian access to animal resources. Analysis of the bone concentrations shows a collaborative tendency between family units within the community. Furthermore, the faunal assemblage tends to show an annual occupation of the site. Sedentary occupation of the site is also supported by ceramic analysis and cultigen analysis. Finally, we compare the mammal NISP and MNI of the McDonald's site with seven other contemporaneous archaeological sites from the region. This comparison shows that mammalian resources declined in importance in the Iroquoian diet between the beginning of the 14th century and the first part of the 16th century, probably due to the adoption of horticulture. / Ce mémoire porte sur l'exploitation de la faune par les habitants du site McDonald de la région de Saint-Anicet. L'objectif principal est de caractériser la place des mammifères dans l’économie mixte des Iroquoiens du Saint-Laurent à un moment où l’horticulture gagne en popularité. L’étude de l’assemblage faunique a permis de déterminer que le cerf de Virginie, l’ours noir et le castor du Canada sont les principaux taxons mammaliens qui contribuent de façon économique, technologique et symbolique à l’économie de subsistance des habitants du site McDonald. Cette étude a été menée en intégrant des statistiques descriptives propres à la zooarchéologie telles que le nombre de restes déterminés (NRD), le nombre minimal d’individus (NMI) et le poids de viande (PV) avec des sources d’informations connexes telles que des documents ethnohistoriques, des guides fauniques et des statistiques gouvernementales. Ce travail utilise également l’analyse de la distribution spatiale des restes squelettiques qui montre une répartition des matières dures animales majoritairement alignée dans l’axe central des maisons-longues. La distribution spatiale des taxons montre quant à elle une homogénéité dans la dispersion des animaux entre les maisons-longues, ainsi qu’une répartition relativement égalitaire des ressources carnées entre les unités familiales. L’analyse des concentrations révèle même un esprit de collaboration entre les unités familiales contiguës. De plus, le spectre de faune tend à démontrer une occupation annuelle du site, ce qui corrobore l’analyse céramique et l’analyse des cultigènes. Finalement, en comparant le NRD et le NMI mammalien du site McDonald avec sept autres sites contemporains, l’analyse faunique démontre que les ressources mammaliennes sont en décroissance dans l’alimentation des Iroquoiens entre le début du 14e siècle et la première moitié du 16e siècle, période qui correspond justement à l’essor de l’horticulture (maïs, haricot, courge) au sein de la diète iroquoienne, ce qui caractérise l’économie mixte de la période du Sylvicole supérieur.
295

Dielektrické vlastnosti rostlinných olejů pro elektrotechniku / Dielectric Properties of Vegetable Oils for Electrical Engineering

Spohner, Milan January 2021 (has links)
The dissertation thesis deals with the analysis of prospective environmentally compatible electrical insulating fluids for electrical engineering in relation to their chemical structure. The thesis starts with the overview of the current state of the art and of the latest trends in the use of synthetic and biodegradable natural oils. In the experimental part were studied these oils: mineral oils, rapeseed oil, sunflower oils, soybean oil, methyl oleate, peanut oil, MCT oil, castor oil and other. Dielectric properties were measured using LRC meter Agilent 4980A including dielectric liquid test fixture Agilent 16452A and also by the Novocontrol Alpha-A analyzer. Electrical properties are presented in the frequency range 10 mHz – 1 MHz range in the temperature interval 253 K to 363 K. The work goes on with the study of the suitability of individual oils for lower temperature, including the impact of the chemical structure and formulation on electrical properties.
296

Soundscape dynamics in the social-ecological systems of Tierra del Fuego

Dante P Francomano (9738650) 14 December 2020 (has links)
<p>Human society is presently beset by an array of anthropogenic social-ecological crises that threaten the sustainability of the social-ecological systems that sustain our livelihoods. While research alone will not rectify these issues, it can help to answer key questions that must be addressed to develop effective solutions. To address such questions in a cohesive, compelling manner, social-ecological research can be bounded, structured, and distilled through innumerable organizing principles or theoretical frameworks. For this dissertation, I focused on the geographic region of Tierra del Fuego and sought to draw from the array of disciplines and methods that use sound as a lens for biological, ecological, and/or social inquiry. I also endeavored to consider various temporal, spatial, and organizational scales while investigating a selection of topics with a) specific importance in the social-ecological systems of Tierra del Fuego and b) general relevance to global social-ecological challenges. Chapter 1 provides an introduction to the dissertation, and Chapter 6 serves as a conclusion.</p><p><br></p><p> </p><p>The objective of Chapter 2, “Biogeographical and analytical implications of temporal variability in geographically diverse soundscapes”, was to provide some guidance to passive acoustic monitoring (PAM) practitioners on how to design appropriate temporal sampling schemes based on the temporal variability of the sounds one wishes to measure and the power and storage limitations of acoustic recorders. We first quantified the temporal variability of several soundscape measurements and compared that variability across sites and times of day. We also simulated a wide range of temporal sampling schemes in order to model their representativeness relative to continuous sampling.</p><p><br></p><p> </p><p>For Chapter 3, “Sentinels for sentinels: passive acoustic and camera trap monitoring of sensitive penguin populations”, we tested the utility of PAM to monitor behavior and abundance of Magellanic (<i>Spheniscus magellanicus</i>) and southern rockhopper penguins (<i>Eudyptes chrysocome</i>) at different spatial and temporal scales. We conducted <i>in situ</i> observations of the acoustic behavior of each species, and we compared acoustic metrics with penguin counts from narrowly focused camera traps and larger-extent observations of colony density. </p><p><br></p><p> </p><p>Chapter 4, “Acoustic monitoring shows invasive beavers (<i>Castor canadensis</i>) increase avian diversity in Tierra del Fuego”, is focused on impacts of the invasive North American beaver (<i>Castor canadensis</i>) on Fuegian bird communities. We sought to determine how bird communities might differ between intact riparian forests, beaver ponds, and beaver meadows created by pond drainage. We conducted PAM and classic avian point counts under each of these conditions across seasons to test for differences between impact conditions and to compare the two methodologies.</p><p><br></p><p> </p>For Chapter 5, “Human-nature connection and soundscape perception: insights from Tierra del Fuego, Argentina”, we evaluated the relationship between soundscape perception and nature relatedness by conducting surveys and soliciting responses to soundscape audio prompts. We also examined the potential for any demographic influences on nature relatedness or soundscape perception in the context of local social tensions.

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