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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.
71

Efeito do preparo sobre a emissão de CO2 do solo em áreas agrícolas descrita por modelo exponencial decrescente no tempo

Teixeira, Luís Gustavo [UNESP] 21 June 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-06-21Bitstream added on 2014-06-13T20:37:33Z : No. of bitstreams: 1 teixeira_lg_me_jabo.pdf: 3324980 bytes, checksum: c588c0fe971e863b13d299ae775c6afb (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Usina São Martinho / O preparo do solo tem sido apontado como uma das práticas que causam perda adicional de carbono do solo para a atmosfera na forma de CO2, o principal gás do efeito estufa ampliado. Neste trabalho são estudados alguns aspectos da emissão de CO2 do solo de áreas agrícolas na região de Jaboticabal, SP, Brasil. Os experimentos foram realizados em duas áreas onde estudou-se o efeito do preparo do solo com arado de disco seguido de grade niveladora (convencional), escarificador de arrasto conjugado com rolo destorroador (reduzido) e enxada rotativa sobre as emissões de CO2 do solo. No experimento conduzido com a enxada rotativa, foi considerada sua aplicação sobre parcela com e sem palha de cana-de-açúcar, sendo o efeito da presença ou não de palha na superfície do solo sobre as emissões de CO2 também investigada. Já no experimento que contemplou o preparo convencional e reduzido as emissões totais indicaram que o sistema de preparo arado de disco seguido de grande niveladora foi o mais impactante, resultando em uma perda de carbono do solo próxima a 71 g m-2 (260 g CO2 m-2) em 2 semanas. Com relação à influência da palha sobre as emissões após preparo, essas foram significativas aumentando a emissão em 36% acima daquela da parcela após preparo sem palha. Os resultados apresentaram, invariavelmente, uma queda da emissão de CO2 do solo ao longo do tempo após preparo, que foi melhor modelada em um dos experimentos a partir de uma função exponencial decrescente no tempo somente, enquanto no outro experimento por uma função combinada, exponencial decrescente no tempo e dependência linear com temperatura e umidade do solo, foi a que melhor ajustou-se as variações temporais da emissão após preparo / Soil tillage has been presented as one of the practices responsible for the additional release of carbon from soil to atmosphere as CO2, the major gas of the enhanced greenhouse effect. This work investigates several aspects of soil CO2 emission in agricultural areas in Jaboticabal region, São Paulo State, Brazil. The experiments were conducted in two fields, where the effect on soil CO2 emissions was studied for tillage employing disk plow followed by offset disk harrow, chisel plow followed by clod break roller and rotary tillage. In the rotary tillage experiment, plots with and without sugarcane trash on the surface were considered, being the effect of the presence of crop residues on soil CO2 emission also evaluated. In the experiment comparing conventional and reduced tillage, total emissions indicated that the conventional tillage (disk plow followed by offset disk harrow) was the most impacting tillage system, resulting in a total carbon emission of 71 grams m-2 (260 g CO2 m-2) in 2 weeks after tillage. Concerning the influence of sugarcane trash on emissions after tillage, emissions were significant, increasing 36% over the plot without residues of the crop. In all cases, results consistently showed a decrease in soil CO2 emission in time after tillage, which was best modeled by an exponential decay in time after tillage only, for one of the experiments, while a combined function of exponential decay in time and linear dependence on temperature and soil moisture, in the other experiment, was the best for fitting the temporal variation of emission after tillage
72

Sustentabilidade e a gestão compartilhada dos resíduos sólidos no município de Ribeirão Preto/SP : conflitos e desafios

Pirani, Nikolas de Camargo 15 March 2010 (has links)
Made available in DSpace on 2016-06-02T19:25:28Z (GMT). No. of bitstreams: 1 2965.pdf: 1354444 bytes, checksum: e4f7e2ff30769f2e32f952db86d22fa7 (MD5) Previous issue date: 2010-03-15 / In urban Brazil, environmental problems have multiplied and have impacts in the worse conditions of living. The social sciences fall into this debate with the understanding that environmental problems arise as a result of economic and social organization. Are the differences in social form of production that determine what materials to use, the rate that will be used and the interaction with the environment. Currently, the production of solid waste is increasing and its inappropriate disposal in most municipalities. Since the late 1980s, have multiplied the experiences of municipal waste collection programs in partnership with recyclable material, organized in associations and cooperatives. These partnerships are called shared management of municipal solid waste and represent a model that seeks to promote economic, environmental and social. However, in practice, these partnerships face serious challenges to the efficiency of the municipal waste collection. The research aims to examine the guidelines of the joint management of solid waste in the municipality of Ribeirão Preto in order to raise the proposals put into practice and the noticeable results of these policies on an assessment that takes into account the three pillars of sustainability. / No contexto urbano brasileiro, os problemas ambientais têm se multiplicado e os impactos ocasionados têm agravado as condições de vida da população. As Ciências Sociais se inserem neste debate com o entendimento de que os problemas ambientais surgem como resultado da organização econômica e social. São as diferenças na forma social de produção que determinam que materiais são usados, seu ritmo de utilização e a interação geral com o meio ambiente. Atualmente, a produção de resíduos sólidos urbanos é crescente e sua destinação inadequada na maioria dos municípios brasileiros. Desde o final da década de 1980, multiplicaram-se as experiências municipais de programas de coleta seletiva em parceria com catadores de materiais recicláveis, organizados em associações e cooperativas. Estas parcerias são denominadas gestão compartilhada dos resíduos sólidos urbanos e representam um modelo que visa promover benefícios econômicos, ambientais e sociais. Porém, na prática, essas parcerias enfrentam sérios desafios para a eficiência dos programas municipais de coleta seletiva. A pesquisa se propõe a analisar as diretrizes da gestão compartilhada dos resíduos sólidos no município de Ribeirão Preto/SP a fim de levantar as propostas colocadas em prática e os resultados perceptíveis dessas políticas numa avaliação que leva em conta os três pilares da sustentabilidade (ecológico, econômico e social).
73

Uso de biocombustivel da pirolise rapida da palha de cana em um motor de ciclo Otto / Use of a biofuel obtained from the fast pyrolysis of sugarcane trash in an Otto engine

Pelaez Samaniego, Manuel Raul 20 June 2007 (has links)
Orientador: Luis Augusto Barbosa Cortez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-09T13:04:50Z (GMT). No. of bitstreams: 1 PelaezSamaniego_ManuelRaul_M.pdf: 2941644 bytes, checksum: 7339da84b3d945856dfe27ff9c0c79c4 (MD5) Previous issue date: 2007 / Resumo: Em setembro de 2002 foi promulgada no Estado de São Paulo a Lei Nº 11.241, que dispõe sobre a abolição gradativa do uso das queimadas como método para eliminar a palha de cana-de-açúcar (folhas e pontas) no processo de colheita. Um dos impactos diretos da execução dessa lei será a disponibilidade no curto prazo de grandes quantidades de palha de cana, cujo potencial energético é muito importante, mas precisa do desenvolvimento e/ou adaptação de tecnologias adequadas para seu uso que incluem operações de colheita e processamento termoquímico. Entre as tecnologias aplicáveis ao aproveitamento energético da palha de cana (e da biomassa em geral), a pirólise rápida oferece a vantagem de produzir altas quantidades de derivados líquidos, e outros produtos como carvão vegetal e gases. O uso destes produtos da pirólise é diverso: produção de energia, ou na industria química, dentro do conceito de bio-refinaria. No contexto apresentado, o presente trabalho realiza a avaliação técnica do uso dos ésteres dos ácidos carboxílicos derivados do bio-óleo de pirólise da palha de cana misturados com gasolina em um motor Otto. Para isto, a palha de cana foi acondicionada e depois pirolisada na planta de pirólise rápida PPR-200, de propriedade da Unicamp. Os produtos foram o bio-óleo, finos de carvão vegetal, gases de pirólise e ácido pirolenhoso. Do bio-óleo obtido foram extraídos os ácidos carboxílicos, mediante esterificação de Fisher em meio ácido, usando etanol, dando como resultado um composto denominado de bioflex. A palha de cana-de-açúcar, o bio-óleo de pirólise e o bioflex foram caracterizados para determinar suas propriedades físicas e químicas. O Poder Calorífico Inferior (PCI) do bio-óleo resultou em 21,46 MJ/kg. No caso do bioflex, o PCI foi 31 MJ/kg. Foram desenvolvidos testes preliminares para determinar as possibilidades de misturar o bioflex com combustíveis derivados do petróleo. Observou-se impossibilidade de misturar bioflex com diesel, e as porcentagens de mistura com gasolina tipo A foram baixas (até 3%). Quando se usou gasolina tipo C se conseguiu maior adição de bioflex na gasolina. Das misturas bioflex-gasolina C, a de maior interesse resultou a denominada G90-B10 (90% de gasolina tipo C com 10% de bioflex), a qual foi utilizada nos ensaios em um motor-gerador elétrico de gasolina de 2 KVA. Nesse motor foram avaliados e comparados: variação de potência com a carga aplicada, consumo de combustível, etc., quando usadas a mistura G90-B10, gasolina tipo A e gasolina tipo C. A carga aplicada durante os ensaios consistiu de um banco de resistências elétricas variáveis desde 200 W até 2000 W. A medição da potência elétrica gerada foi efetuada sob distintas condições de carga e diferentes regimes de rotação do eixo do motor. Os resultados mostraram que a potência gerada pelo gerador e o consumo de combustível do motor são similares quando usados os três combustíveis, fato que permite concluir que é tecnicamente viável o uso do bioflex misturado com gasolina C em proporções 10/90 em motores de ciclo Otto / Abstract: In September 2002 the state of São Paulo promulgated the Law Nº 11241 by which was codified the gradual elimination of fire as a method to remove trash from the sugar-cane fields before harvestig. Large amounts of sugar-cane trash with an important energy potential will be available as a result of this law. New technologies to harvest and process this biomass need to be developed and/or adapted. Amongst the potential concepts to use the energy contained in sugar-cane trash, fast pyrolysis offers important advantages since high liquid yield, char and syngas can be obtained with this technology. These materials can be used to produce energy or chemicals in power plants or in new bio-refineries. A technical evaluation of using carboxylic acids ethyl esters derived from sugar-cane trash bio-oil, mixed with gasoline in an Otto engine is presented. The sugar-cane trash was ground, dried and further pyrolyzed in the PPR-200 fast pyrolysis plant, owned by Unicamp. The products were: a decanted bio-oil, an aqueous phase, charcoal fines and pyrolitic gases. The carboxylic acids were extracted from the decanted oil and esterified by the Fisher acid catalyzed method, using ethanol. The resulting product was called bioflex. The sugar-cane trash, the bio-oil and the bioflex were characterized to determine their physico-chemical properties. The Lower Heating Value (LHV) of the bio-oil resulted 21,46 MJ/kg. In the case of bioflex, its LHV was 31 MJ/kg. Preliminary tests were performed to evaluate the fuel performance of bioflex /conventional petroleum derived fuel blends. The bioflex was not miscible in diesel and only very low amount (3 vol %) was soluble in gasoline type A. Larger solubility was observed with Brazilian gasoline type C. The blend containing 90% of gasoline type C and 10% of bioflex, herein called G90-B10, presented the biggest interest so was used as fuel in a 2 KVA electric Otto engine-generator. The engine power versus applied load, fuel consumption, etc., when used G90-B10 mixture, gasoline type A and gasoline type C were evaluated and compared. The load applied during the tests consisted of a variable electric resistance with capacity from 200 W to 2000 W. The measurement of the generated electricity was made under different load conditions and under different shaft-engine rotation speed. Results showed that the power generated and the fuel consumed by the engine was similar when using the three fuels. These results confirm the technically viability of 10/90 (bioflex-gasoline C) blends as fuels in Otto engines / Mestrado / Mestre em Planejamento de Sistemas Energéticos
74

Concerns and perceptions of taxi drivers and hawkers regarding littering at Mabopane station

Mmatau, Nchancha Dorothy 09 February 2015 (has links)
M.Ed. (Environmental Education) / Please refer to full text to view abstract
75

Pirólise rápida de cana-de-açúcar integral em reator piloto de leito fluidizado / Fast pyrolysis of whole sugarcane in pilot-scale fluidized bed reactor

Baldassin Junior, Ricardo, 1979 03 May 2015 (has links)
Orientador: Luís Augusto Barbosa Cortez / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-28T23:42:55Z (GMT). No. of bitstreams: 1 BaldassinJunior_Ricardo_D.pdf: 7640744 bytes, checksum: d5dd82917b9ece7e8fac5e0eaf729326 (MD5) Previous issue date: 2015 / Resumo: A transformação eficiente e sustentável de materiais lignocelulósicos em bioenergéticos e bioquímicos modernos é um dos grandes anseios da sociedade moderna, haja vista as vantagens competitivas, os potenciais de redução da expansão da fronteira agrícola e a redução da dependência do petróleo que somente as culturas bioenergéticas podem proporcionar. Neste contexto, o Brasil apresenta um cenário propício para o desenvolvimento de uma indústria inovadora e moderna de produção de biocombustíveis e bioquímicos verdes, por ser um dos maiores produtores mundiais de alimentos, florestas plantadas e biocombustíveis. Visando promover a conversão eficiente de materiais lignocelulósicos, resíduos estes abundantes no Brazil, este trabalho apresenta os primeiros resultados da experimentação de pirólise rápida de cana-de-açúcar (cana integral, palha e bagaço) em uma unidade experimental da Feagri/Unicamp. Este estudo teve por objetivo avaliar as características químicas das biomassas empregadas e quantificar e qualificar os produtos da pirólise obtidos (bio-óleo e carvão). As análises químicas das biomassas (imediata, elementar e fibras/lignina) apontaram que não há diferenças significativas entre as diferentes biomassas analisadas. Os processos de pré-tratamento (picagem e trituração) foram conduzidos de forma satisfatória usando tecnologias comerciais e processo de secagem ao sol mostrou ser eficiente na redução da umidade das biomassas. Após a realização de ajustes e adequações em alguns componentes da planta, os experimentos de pirólise foram conduzidos satisfatoriamente e os rendimentos mássicos de produção de bio-óleo e carvão observados estiveram entre 12% e 17% e entre 25% e 27%, respectivamente, que em termos energéticos, representaram conversões variando entre 42% e 67%. As análises químicas dos bio-óleos e dos carvões mostraram não haver diferenças significativas entre os produtos obtidos. Entretanto, as análises cromatográficas dos bio-óleo sinalizaram haver diferenças nas composições orgânicas do bio-óleo, mas com as predominâncias de ácidos carboxílicos e fenóis. Em vista da baixa recuperação de bio-óleo, elevada produção de carvão e a elevada presença de voláteis no carvão (entre 20% e 25%) verificaram-se necessidades de melhorias e as realizações de novos estudos na unidade experimental desenvolvida / Abstract: The efficient and sustainable conversion of lignocellulosic feedstocks in modern biofuels and biochemicals is one of the great desires of the whole world, in view of the competitive advantages, potential of reduction of frontier agriculture expansion and reduction of oil dependence that only the bioenergy cultures may provide. In this context, Brazil shows an attractive scenery to develop an innovative and modern industry for biofuels and biochemical production, since it is one of the most important food, planted forest and biofuels world producer. Aiming to provide a better use and conversion of lignocellulosic feedstocks (largely available in Brazil), this work shows the first experimental results of the fast pyrolysis of sugarcane (whole sugarcane, trash and bagasse) conducted in a small scale fast pyrolysis plant from Feagri/Unicamp. The main objectives of this work were to evaluate the chemicals compositions of the biomasses and to quantify and to qualify the main fast pyrolysis products (charcoals and bio-oils). The biomasses analysis (proximate, ultimate and fiber/lignin analysis) showed there were no significant differences between the biomasses. The pretreatment process (chopping and grinding process) were conducted well using conventional technologies, and the sun drying process was able reducing the biomasses water contents to the level needed. After some adjustments and improvements, the fast pyrolysis were conducted well, with bio-oil yield productions between 12% and 17%, charcoal yield productions between 25% and 27%, and energy conversions between 42% and 67%. The bio-oils and charcoals proximate and ultimate analysis showed that there were no relevant differences among the products. However, the chromatography analysis demonstrated there were differences in the bio-oils organic compositions (distribution percentages of chemical groups), but with prevalence of carboxilic acids and phenols. In view of low bio-oils production, high charcoals productions and the high volatiles presences in the charcoals (between 20% e 25% in %wt), it was demonstrated that improvements and new studies are needed / Doutorado / Construções Rurais e Ambiencia / Doutor em Engenharia Agrícola
76

The Eco-Smart Can V2.0

Nanto, Darack B 01 May 2019 (has links) (PDF)
On a scorching summer day in 2015, a campus maintenance worker was observed emptying a trash bin. Upon closer observation, it was noted that the bin was not full; in fact, it was less than one third full. There were other bins that were full and needed to be emptied urgently. It was confusing and problematic to see that bins that needed more attention were not prioritized. After extended research, it was found that maintenance operates on daily routes to pick up trash at designated times, regardless of the level of trash in the bins. Therefore, to tackle this issue, the author decided to use the Internet of Things (IoT) to develop a prototype that will optimize trash collection and reduce costs of waste management and pollution; this device is named the Eco-Smart Can.
77

Ogräsrensning i insjöträdgården : Fiskutrotning under det svenska ”rotenonprojektet”, ca. 1950–1970 / Weed Control in the Lake Garden : Fish Eradication During the Swedish "Rotenone Project", ca. 1950-1970

Sigvardson, Inez January 2024 (has links)
This thesis explores the historical practice of managing lakes and other bodies of water with the idea to create good fishing waters for fishers and anglers. The starting point for the thesis is the use of rotenone as a piscicide to exterminate the fish populations in Swedish lakes between 1950-1970. Rotenone was used to create empty waters for the purpose of fish stocking with species of fish that were seen as more valuable for recreational fishermen. The study analyzes the use of rotenone as a method for controlling parts of nature for human profit and use. From a perspective of conservation, fishers advocated for the use of rotenone as a way to ensure the success of the fish stocking practices. I show that how metaphors connected to gardening and farming was used during the legitimization of the rotenone method to describe the species of fish which were the targets for eradication. The fish deemed unvaluable were described as weeds or trash which connected to the idea of extermination of those species. Furthermore, the treatment with rotenone was part of a bigger project in Sweden, for the establishment of public areas in nature in which citizens could practice outdoor recreation. With a framework of more- than-human entanglements I analyze the rotenone project as acts of domestication of water and fish, which additionally connected to the idea that humans should be in control of nature. The question of animal agency entered the discourse surrounding rotenone, because of the weed- fish’s tendency to return to the treated waters. The fish’s agency and intentionality were most often referred to through an anthropomorphic lens, and they were thus attributed with a human understanding of intent. I argue that the inability to see the fish’s own agency and the desire to control nature through separation were contributing factors in the failure of the rotenone project.
78

Alternativní řešení a pevnostní kontrola mechanických česlí / Alternative solution and strength check of mechanical screens

Sommer, Matěj January 2020 (has links)
This master’s thesis deals with a new design of bar screens. The goal was to come up with an alternative design to already existing device by INKOS a. s. In the first part, there is a summary of various machines working in similiar conditions. The insights gained by this research influenced the design of the new device. It utilizes well proven solutions from previous projects, but some of these were reworked and a few new functions were added. Second part of the thesis describes the analytical solutions, which were used to determine the forces in the assembly during the operation of the device. Based on the results of these calculations, a strength analysis of important components was performed using the finite element method. The result of this thesis is the design and optimization of new bar screens, including engineering drawings and tools for its further development.
79

Op weg na 'n kontemporere eko-estetiek

Harley, Magdalena Johanna Gertruida 12 1900 (has links)
Thesis (MA)-- Stellenbosch University, 2003. / ENGLISH ABSTRACT: On the way to a contemporary eco-aesthetic. My thesis consists of three chapters; the first chapter contains a basic background study and philosophic research of concepts which are relevant to my work; the second chapter is a discussion of ecofeminism as political and spiritual phenomena (my work resorts in the genre of ecofeminism); and the third chapter is an analytic consideration and discussion where my works are presented as a visual explanation of my own interpretation of the dialogue between art and science with underlying geographical and ecological concepts. Some of these concepts purport the ritual of cycles and the aesthetic experience thereof. They deal with the earth as maternal patron where the layers of society (evidence of existence) becomes evident in the layering of the earth. This evidence of existence can be found in the waste generated from the cyclic existence of living beings and organisms. In addition, the traditional scrub or healing activities which are ascribed to women, are used as an argument to effectuate a consciousness of symbioses. / AFRIKAANSE OPSOMMING: My tesis bestaan uit drie hoofstukke; die eerste hoofstuk behels 'n basiese agtergrondstudie en filosofiese ondersoek na konsepte wat na my mening betrekking het op my werk; die tweede hoofstuk is 'n bespreking oor ekofeminisme as politieke en spirituele verskynsel (my werk ressorteer onder ekofeminisme as genre); en die derde hoofstuk 'n analitiese beskouing en bespreking waar my werk aangebied word as visuele verduideliking van my persoonlike interpretasie van die dialoog tussen kuns en wetenskap met onderliggende geografiese en ekologiese konsepte. Van hierdie konsepte gaan oor die ritueel van siklusse en die estetiese belewenis daarvan. Dit handeloor die aarde as die moederskoot waar die lae van samelewings (bewyse van bestaan) gelees kan word in die gelaagdheid van die aarde. Hierdie bewyse van bestaan kan gevind word in die afval wat gegenereer word uit die sikliese bestaanswyse van lewende wesens en organismes. Hiermee saam word die tradisionele skrop- of helende aktiwiteite wat aan vroue toegeken word, as argument gebruik om 'n bewussyn van simbiose te bewerkstellig.
80

Identifying Cultural and Non-cultural Factors Affecting Litter Patterns in Hickory Creek, Texas

Carpenter, Evan S. 08 1900 (has links)
Plastic deposition in hydrological systems is a pervasive problem at all geographic scales from loci of pollution to global ocean circulation. Much attention has been devoted to plastic deposition in marine contexts, but little is known about inputs of plastics into local hydrological systems, such as streams. Any attempt to prevent plastic litter must confront people’s behaviors, so archaeological concepts are used to distinguish between various cultural inputs (e.g., littering) and non-cultural forces (e.g., stream transport) that affect litter patterns on the landscape. Litter surveys along Hickory Creek in Denton, TX, are used to assess these factors.

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