741 resultados para Areia


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RESUMO: Os solos da região Noroeste do Paraná apresentam cerca de 85 a 90% de areia e níveis críticos de nutrientes, conferindo alta suscetibilidade à erosão e baixa capacidade de armazenamento de água. Além disso, a região apresenta clima quente, tornando-a bastante vulnerável a estresses abióticos. Uma das estratégias para aumentar a produtividade e, ao mesmo tempo, incrementar serviços ambientais é aumentar a diversidade de atividades, por meio do sistema de integração lavoura-pecuária-floresta (iLPF). O sistema iLPF pode conferir maior taxa de sequestro de carbono, conservação da biodiversidade e melhoria da qualidade do solo, água e ar, em comparação a sistemas não integrados. No município de Santo Inácio, PR, foram conduzidas por cinco anos duas áreas com sistema iLPF. Nos três primeiros anos de condução, foi possível conciliar a produção de grãos (soja), forragem (Brachiaria ruziziensis e B brizantha ) e madeira (eucalipto), sem que um componente prejudicasse o outro. A partir do terceiro ano, as árvores interferiram expressivamente na produtividade de grãos e forragem, indicando a necessidade de redução do número de árvores por área. O iLPF é um sistema de produção relevante para aumentar a provisão de bens e serviços ecossistêmicos na região Noroeste do Paraná, mas que ainda precisa de ajustes tecnológicos para incrementar os ganhos econômicos e ambientais. ABSTRACT: Most soils in Northwest of Paraná state, Brazil, are sandy (85 to 90% sand), with critical nutrient levels, high susceptibility to erosion and low water storage capacity Moreover, the region?s warm weather confers to these soils high vulnerability to abiotic stresses The diversification of production via adoption of integrated cropping-livestock-forestry (ICLF) systems is an important strategy to increase productivity and, simultaneously enhance ecosystem services. ICLF systems can increase carbon sequestration, conserve biodiversity and improve soil, water and air quality, compared with specialized production systems. Two trials were carried out for five years using ICLF in Santo Inácio county in Paraná state, Brazil. In the first three years, it was possible to harmonize production of grains (soybean), fodder (Brachiaria ruziziensis and brizantha) and wood (Eucalyptus) without negative effects of three components on each other. After the third year, the trees significantly reduced grain yield and fodder production, indicating the need for thinning to reduce tree interference. The ICLF system is relevant to increase the delivery of ecosystem goods and services in Northwestern Paraná, though technological adjustments are needed to increase its economic and environmental gains.

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This dissertation is an attempt to understand how families with an income of up to three minimum wages and living in different Areas of Demographic Expansion (AEDs) of Natal municipality specifically in the districts of Igapó and Salinas (North Administrative Zone of the city), Ponta Negra (South Administrative Zone), Santos Reis, Praia do Meio, Areia Preta and Mãe Luíza (East Administrative Zone) and Felipe Camarão (West Administrative Zone) solve their problems of urban mobility. It is, therefore, a reflection upon the mobility needs of poor urban households as expressed in terms of origin-destiny displacements for specific movements (house-work, house-school, house-shopping, house-healthcare and house-leisure), all of which being analyzed within the relationship between public transportation and poverty spaces of the city. In order to develop the study, theoretical aspects and themes related to the production of the urban space, to social and spatial segregation, to urban mobility and to transportation were confronted with the collected data referring to the urban population previously selected. One of the research main findings is the crucial role mobility plays in the social differentiation of such people living in Natal and that any policy for the improvement of their living conditions must take mobility issues into account

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Dissertação de mest. em Estudos Marinhos e Costeiros Ramo Gestão Costeira, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2002

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The sharp consumption of natural resources by the construction industry has motivated numerous studies concerning the application of waste to replace partially or fully, some materials, such as aggregates, thereby reducing the environmental impact caused by the extraction of sand and crushing process. The application of stone dust from crushing process arising as an aggregate for the production of Portland cement concrete is a viable alternative in view of the high cost of natural sands, in addition to the environmental damage which causes its operation to the environment. The stone dust has reduced cost compared to natural sand because it is produced in the beds of their own quarries, which are usually located close to major urban centers. This study examined the feasibility of using stone dust from the crushing of rock gneisses in the state of Bahia, replacing natural quartz sand. In the development of scientific study was conducted to characterize physical and chemical raw materials applied and molded cylindrical specimens , using as reference values Fck 20, Fck 25 and Fck 30 MPa ( resistance characteristic of the concrete after 28 days) in following compositions stone powder: 10%, 30%, 50 %, 100% and 100% with additive. The specimens were cured and subjected to the tests of compressive strength and water absorption, then the samples were subjected to the tests of X-ray diffraction and scanning electron microscopy. The results obtained showed that the composition with 10% stone powder showed the best results regarding the physical and mechanical tests performed, confirming the reduction in compressive strength and increased water uptake increased as the content of the powder stone in the concrete composition

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The coatings mortars are essential elements of building structures because they execute an important role in protecting walls and are particularly exposed to aggressive action responsible for its degradation over time. The importance of wall coverings has been the subject of discussion and analysis in the conservation and rehabilitation of old buildings. Are sometimes removed and replaced with inappropriate solutions of constructive point of view or architecture. The most commonly used coatings on walls of old buildings is based on traditional hydraulic lime mortars. The present study aims at the formulation of new lime- based mortars and aerial fine aggregate, in order to contribute to a better field of conservation and restoration mortar coating of old buildings. Residue was used for polishing porcelain as fine aggregate, replacing the aggregate (sand), in percentages 05-30% by mass. We conducted a thorough evaluation of the mortar properties in fresh and hardened state by comparing the performance of the same with a reference mortar. The residue used was characterized as the density, bulk density, and particle size laser, scanning electron microscopy, X-ray diffraction and X-ray fluorescence. Formulations were produced 7, 6 with residue and one commonly used formulation, which served as a reference. In the formulations of lime mortars air (hydrated lime powder CH-I) has been adopted a stroke volume (1:3) with constant binder, was varied and the water / binder and aggregate and waste. For evaluation of mortars fresh, proceeded to consistency analysis, specific gravity, water retention and air content embedded. In the hardened state assays were performed in specific gravity, water retention, modulus of elasticity, tensile strength in bending, compressive strength, water absorption by capillary action, adhesion, tensile strength, resistance to shrinkage and salts by of crystallization trials with resources chloride solution, nitrate and sulfate all sodium in prismatic at 90 days of age, in addition to the micro structural analysis of mortars. Based on the results we can see that the mortar formulated with 10% content of waste and the reference free retraction feature more stable closer to neutrality. The composition of 10% was obtained better performance against the action of the salt crystallization. The mortar with 15% residue obtained better density, lower air content embedded and high capacity for water retention developing good workability. The replacement of 20% of waste generates a satisfactory utilization of resistance to compression, flexion and traction grip the base. And, finally, it can be seen that the mortar with 10, 15 and 20% residual show, in principle, good suitability as coatings, thus enabling a final result consistent with durability, workability and aesthetics developing therefore a material with better performance to repair or replace existing mortars in old buildings

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A condutividade hidráulica do solo saturado (Ksat) constitui parâmetro de grande relevância nos estudos de vulnerabilidade natural e, por consequência, na avaliação de riscos ambientais. Quando se trata de áreas frágeis, como são as áreas de recarga de aquíferos sedimentares, a avaliação da condutividade hidráulica torna-se ainda mais importante. Para esse estudo, selecionou-se uma área de recarga direta do Aquífero Guarani, caracterizada pela microbacia do córrego Espraiado, localizada na região de Ribeirão Preto (SP). Os principais solos dessa microbacia são Latossolo Vermelho Distrófico psamítico (LVdq) e Neossolo Quartzarênico Órtico (RQo). Para a avaliação da condutividade hidráulica (Ksat) desses solos utilizou- se o método da coluna saturada, cujos valores foram correlacionados com os de textura e estrutura do solo, considerados os parâmetros diretamente relacionados à Ksat. As correlações foram diretas entre os valores de Ksat e os de textura arenosa (areia). Já para a estrutura do solo, essa correlação ocorreu de forma indireta, indicando menor influência desse parâmetro sobre a condutividade hidráulica do solo saturado.

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Sabe-se que ao longo do ciclo da mamoneira são produzidos racemos de várias ordens que se desenvolvem sob diferentes condições ambientais, as quais podem provocar variações na qualidade das sementes no campo e durante o armazenamento. Assim, objetivou-se avaliar o efeito de diferentes tratamentos de colheita (ordens de racemos e épocas) e da armazenagem na qualidade fisiológica de sementes de mamona, cultivar IAC-2028. Foram instalados testes de germinação, emergência de plântulas em areia, velocidade de emergência e crescimento de plântulas, logo após a colheita e aos 3, 6, 9 e 12 meses de armazenamento em ambiente de laboratório, sem controle de temperatura e umidade relativa do ar. O delineamento experimental adotado foi em blocos ao acaso, com cinco repetições, em esquema de parcela subdividida, onde as parcelas foram constituídas por cinco períodos trimestrais de avaliação e as sub-parcelas de 11 tratamentos de colheita. Com base nos resultados obtidos, conclui-se que a colheita dos racemos de mamona da cultivar IAC-2028, nas condições deste experimento, pode ser realizada em uma única etapa sem que ocorram perdas de qualidade fisiológica das sementes e o armazenamento manteve satisfatoriamente a qualidade das mesmas

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A sustentabilidade dos recursos marinhos da costa portuguesa tem sido de forma crescente posta em causa devido a variados factores, nomeadamente pelo aumento do esforço da pesca, com consequência na redução de alguns mananciais (e.g. pescada, lagostim), conduzindo a uma grande apreensão no que concerne à sua gestão. Por outro lado, novos desafios têm surgido na última década, sobretudo no contexto da gestão espacial (Planeamento Espacial Marítimo / Marine Spatial Planning), com particular evidência na costa algarvia. Devido ao aumento das actividades no mar, aquaculturas em mar aberto, armações de atum, áreas de reserva de areia (manchas de empréstimo) e zonas de fundeio, mas também devido às disputas entre as diferentes frotas pesqueiras, a gestão espacial tem estado cada vez mais na ordem do dia. Estes factos foram em grande medida os principais motivadores e impulsionadores para a execução do presente projecto. O presente estudo encontra-se integrado no projecto “Mapeamento de bancos de pesca algarvios PescaMap) do Programa Operacional Pesca 2007-2013 (Promar), co-financiado pelo Fundo Europeu das Pescas (FEP). O projecto contou com os apoios institucionais da Cooperativa dos Armadores de Pesca do Barlavento CRL (BarlaPescas), da Docapesca, Marina de Lagos, da Associação dos Pescadores do Portinho da Arrifana e Costa Vicentina (APPACV) e da Câmara Municipal de Aljezur.

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A sustentabilidade dos recursos marinhos da costa portuguesa tem sido de forma crescente posta em causa devido a variados factores, nomeadamente pelo aumento do esforço da pesca, com consequência na redução de alguns mananciais (e.g. sardinha, pescada, lagostim), conduzindo à grande apreensão no que concerne à sua gestão. Por outro lado, novos desafios têm surgido na última década, sobretudo no contexto da gestão espacial (Planeamento Espacial Marítimo / Marine Spatial Planning), com particular evidência na costa algarvia. Devido ao aumento das actividades no mar, aquaculturas em mar aberto, armações de atum, áreas de reserva de areia e zonas de fundeio, mas também devido às disputas entre as diferentes frotas, a gestão espacial tem estado cada vez mais na ordem do dia. Estes factos foram em grande medida os principais motivadores e impulsionadores para a execução do presente projecto. O presente estudo encontra-se integrado no projecto “Mapeamento de bancos de pesca algarvios (PescaMap) do Programa Operacional Pesca 2007-2013 (Promar), co-financiado pelo Fundo Europeu das Pescas (FEP). O projecto contou com os apoios institucionais da Cooperativa dos Armadores de Pesca do Barlavento CRL (BarlaPescas) e da Câmara Municipal de Aljezur.

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This research was motivated by the requirement of asbestos s replacement in building systems and the need to generate jobs and income in the country side of the state of Bahia, Brazil. The project aimed at using fibers from licuri leaves (syagrus coronata), an abundant palm in the region, to produce composites appropriate for the sustainable production of cement fibre reinforced products in small plants. The composites were produced in laboratory using Portland cement CP-II-F32, sand, water, licuri palm fiber contents of 1.0, 1.5 and 2.0% by weight of binder (two different fiber length) and metakaolin. The latter was chosen as an additional binder for its efficiency to reduce the alkalinity of cementitious matrixes therefore preventing the degradation of vegetable fibers. The characterization of the composite components was carried out by sieving and laser particle size analyses, thermal analysis, fluorescence and X-ray diffraction. The composites performance was evaluated by 3- point-bending tests, compressive strength, ultrasound module of elasticity, free and restrained shrinkage, water capillarity absorption and apparent specific gravity. It has been found that the addition of fibers increased the time to onset of cracking over 200.00% and a 25% reduction in cracks opening in the restrained shrinkage test. The capillary absorption reduced about 25% when compared to fiber-free composites. It was also observed with regard to flexural strength, compressive strength and specific gravity, that the addiction of fibers did not affect the composite performance presenting similar results for compounds with and without fibers. In general it can be stated that the reinforced composite fibers of palm licuri presents physical and mechanical characteristics which enable them to be used in the intended proposals of this research

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Researches have shown that the introduction of rubber in concrete improves the features of its deformability, as well as contributes to environmental disposal of waste generated in the tire retreading process. Furthermore, there is a high availability of limestone within RN and CE country. Ignorance about this stone, does not allow its wide use as aggregate, leaving, this abundant supply idle. A composite of limestone gravel, with proportions of tire rubber waste which could be used as concrete would be an alternative to concrete for low applications. Therefore, this research aims to evaluate the characteristics of concrete containing limestone gravel and proportions of little aggregate replacement (sand) by tire rubber waste. To this goal, the material components of the concrete were characterized, concrete specimens with limestone gravel were made, from the dash 1.0: 2.5: 3.5, varying the water/cement ratio, and inserting a commercial plasticizer, without a proportion of residue, known as reference. From this, concrete with and without the presence of the additive in the same proportions were chosen, as well as these with the use of granite gravel, for being the most used. Selected the references, to these, replacements of little aggregate (sand) were added replaced by rubber waste from the tire retreading process, treated with 1M NaOH in proportions from 5.0 to 20.0 % by mass, cured and exposed to the semiarid environment. The results indicate the possibility of using limestone gravel in the concrete composition with workability correction using plasticizer. There was a decrease in the mechanical properties of the concrete with increments of waste rubber, but there is an improvement in toughness and deformability of the composite, which makes it interesting for the construction of non-structural concrete floors, as well as, the rubber waste delayed the hardening process, continuing to gain resistance after 28 days

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This thesis has as objective presents a methodology to evaluate the behavior of the corrosion inhibitors sodium nitrite, sodium dichromate and sodium molybdate, as well as your mixture, the corrosion process for the built-in steel in the reinforced concrete, through different techniques electrochemical, as well as the mechanical properties of that concrete non conventional. The addition of the inhibitors was studied in the concrete in the proportions from 0.5 to 3.5 % regarding the cement mass, isolated or in the mixture, with concrete mixture proportions of 1.0:1.5:2.5 (cement, fine aggregate and coarse aggregate), superplasticizers 2.0 % and 0.40 water/cement ratio. In the modified concrete resistance rehearsals they were accomplished to the compression, consistence and the absorption of water, while to analyze the built-in steel in the concrete the rehearsals of polarization curves they were made. They were also execute, rehearsals of corrosion potential and polarization resistance with intention of diagnose the beginning of the corrosion of the armors inserted in body-of-proof submitted to an accelerated exhibition in immersion cycle and drying to the air. It was concluded, that among the studied inhibitors sodium nitrite , in the proportion of 2.0 % in relation to the mass of the cement, presented the best capacity of protection of the steel through all the studied techniques and that the methodology and the monitoring techniques used in this work, they were shown appropriate to evaluate the behavior and the efficiency of the inhibitors

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Deep bed filtration occurs in several industrial and environmental processes like water filtration and soil contamination. In petroleum industry, deep bed filtration occurs near to injection wells during water injection, causing injectivity reduction. It also takes place during well drilling, sand production control, produced water disposal in aquifers, etc. The particle capture in porous media can be caused by different physical mechanisms (size exclusion, electrical forces, bridging, gravity, etc). A statistical model for filtration in porous media is proposed and analytical solutions for suspended and retained particles are derived. The model, which incorporates particle retention probability, is compared with the classical deep bed filtration model allowing a physical interpretation of the filtration coefficients. Comparison of the obtained analytical solutions for the proposed model with the classical model solutions allows concluding that the larger the particle capture probability, the larger the discrepancy between the proposed and the classical models

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This study intends to establish a relation between environmental degradation, particularly the devastation of the green canopy, and public health. Utilizing a mapping of the trees included in the researched area, each individual tree was analyzed according to its age, taxonomic listing, architecture, shape and size (determined by aesthetic/convenience reasons or deformed by pruning). Initially investigated were the covert reasons lying underneath the constant aggression against trees (which many times seem to contain elements of hatred and contempt) within the urban environment. In addition to that, the aspects concerning environmental modifications and the consequent impact on public health were also assessed. Two main problems promptly emerged as a result of the removal of trees: a) without a canopy to protect the areas, they became subject to winds directly blown from SW Africa and impregnated with aerosol partic les, which are common causes for respiratory disorders and, b) direct UV solar radiation, which causes some types of skin cancers and eye disorders. To reach such results, we studied the origins and formation of UV radiation induced cancers and searched for the UV radiation spectra of action, e.g., usual intensity and quantity reaching clear and shadowed spaces in a certain area and its consequences. In a second instance, we also searched for pertinent data resources in order to confirm the increase of skin cancer cases due to exposure to UV radiation and the relation between the destruction of the green canopy and the above mentioned problems. We believe that a few significant results have been achieved by this study, namely: the relation between a culture based on medieval beliefs and its consequences on the environment; how this culture exploits and deforms nature in pursuit of financial and psychological interests to a point of transforming the landscape into a copy of something devoid of any relation to latitude and altitude; and above all, the indifference concerning the alarming results carried by these modifications