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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.
91

Desempenho agroenergético, uso de água e de nutrientes por cana-de-açúcar cultivada na Chapada do Araripe / Agroenergetic performance, water use and nutrients by sugar cane cultivated in Chapada do Araripe.

ALBUQUERQUE, Henrique Soares de 28 February 2013 (has links)
Submitted by (lucia.rodrigues@ufrpe.br) on 2016-12-19T14:32:12Z No. of bitstreams: 1 Henrique Soares de Albuquerque.pdf: 584354 bytes, checksum: bc6deba33329982980e33255ca8a5a3f (MD5) / Made available in DSpace on 2016-12-19T14:32:12Z (GMT). No. of bitstreams: 1 Henrique Soares de Albuquerque.pdf: 584354 bytes, checksum: bc6deba33329982980e33255ca8a5a3f (MD5) Previous issue date: 2013-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Araripe Gypsum District is among the major consumers of firewood and coal of Pernambuco State Semiarid. This demand by energy has been partially contemplated to species extracted from the Caatinga biome. The use of biomass from sugarcane for energy purposes can be an alternative for sustainable development in the region. However, plant production in semi-arid depends on several factors, as the water supply, resistance of plants to water stress and the chemical management of soils, dystrophic often in the Chapada do Araripe soils. The gypsum produced in the region is a low-cost alternative to chemical soil management aiming to increase the access of water and nutrients to crops. Thus, objective of the research was to study the production of biomass for energy purposes by varieties of sugar cane grown in the Chapada do Araripe, and the impact of the application of gypsum in soils in the agronergetic potential of sugarcane in semi-arid environment. In this context, were tested three varieties of sugarcane: : RB867515, RB92579 e RB962962; cultivated in Chapada do Araripe distrophic soil, in the presence and absence of gypsum, in factorial arrangement (3x2) distributed in randomized blocks with four replications. The experiment was conducted during the period from 2010 to 2012, two consecutive cycles of of sugar cane growth, in Research Unit of Instituto Agronômico de Pernambuco, in Araripina city, Brazil. For this purpose, were made the determinations of the production of biomass and energy characteristics, such as fibre content, lignin and Higher heating value. Additionally, were determined the efficiency of water use by the varieties of sugarcane, and the extraction and nutrient use efficiency of varieties in the two growing cycles. The data were subjected to analysis of variance being the significant effects compared by Tukey mean test (p<0,05). The application of gypsum did not affect the agroenergetic performance of varieties cultivated in the semiarid. The varieties responded specifically and differently to water stress, declining, on average, the productivity by 38%, keeping the calorific value within the recommended range for bioenergetic material, around 17 MJ kg-1. The better relationship between productivity and calorific value was obtained by the variety RB962962. The application of gypsum provided, in the sugarcane, greater concentration and extraction of sulfur by varieties, as well as higher nitrogen extraction by the second cycle. / O pólo Gesseiro do Araripe está entre os grandes consumidores de lenha e carvão do semiárido de Pernambuco, demanda que tem sido atendida, em parte, por espécies vegetais extraídas da Caatinga. A utilização de biomassa da cana-de-açúcar para fins energéticos pode ser uma alternativa para desenvolvimento sustentável na região. Porém, a produção vegetal no semiárido depende de diversos fatores, como o suprimento de água, resistência das plantas ao estresse hídrico e o manejo químico dos solos, muitas vezes distróficos, como ocorre na Chapada do Araripe. O gesso produzido na região é uma alternativa de baixo custo para o manejo químico de solos visando aumentar o acesso das culturas a água e nutrientes. Assim, o objetivo da pesquisa foi estudar a produção de biomassa para fins energéticos por variedades de cana-de-açúcar cultivadas na Chapada do Araripe, e o impacto da gessagem de solos no potencial agroenergético de cana-de-açúcar em ambiente semiárido. Nesse contexto, foram testadas três variedades de cana-de-açúcar: RB867515, RB92579 e RB962962; em solo distrófico da chapada do Araripe na presença e ausência de gesso, em arranjo fatorial (3X2) distribuídos em blocos casualizados com quatro repetições. O experimento foi conduzido no período de 2010 a 2012, considerando dois ciclos de cultivo da cana-de-açúcar, no Instituto Agronômico de Pernambuco - IPA, em Araripina, Pernambuco. Para tanto, foram avaliadas a produção de biomassa e características energéticas, tais como teor de fibras, lignina e poder calorífico superior. Foram determinadas também a eficiência do uso da água pelas variedades de cana-deaçúcar, e a extração e a eficiência de uso de nutrientes das variedades nos dois ciclos de cultivo. Os dados foram submetidos à análise de variância sendo os efeitos significativos comparados estatisticamente por teste de médias (p<0,05). A aplicação de gesso não afetou o desempenho agroenergético das variedades cultivadas no semiárido, tampouco a eficiência de uso da água pelas mesmas. As variedades responderam de modo específico e diferenciado ao estresse hídrico, diminuindo, em média, a produtividade em 38% na canasoca, mantendo o poder calorífico dentro da faixa recomendada para material bioenergético, em torno de 17 MJ kg-1. De modo geral, a variedade que teve melhor relação entre produtividade e poder calorífico superior foi a RB962962. A aplicação de gesso proporcionou, na cana-soca, maior concentração e extração de enxofre pelas variedades, bem como maior extração de nitrogênio no segundo ciclo.
92

Caractéristiques et fonctionnement des sols dans la vallée de Oued Righ, Sahara Nord Oriental Algérie / Characteristics and functioning of soils in the Valley of Oued Righ, Sahara North Oreintal Algeria

Boumaraf, Belkacem 28 June 2013 (has links)
Au cours de cette étude, nous avons essayé de mettre en évidence les grandes lignes de l'évolution spatiale des caractères pédologiques, de certains sols sur une séquence établie à partir de la carte géomorphologiques, dans la vallée de l'oued Righ, région située dans le Sahara nord-oriental de l'Algérie. Nous avons grâce à une longue prospection choisi une région située sur la bordure nord du chott Mérouane. Là, nous avons pu identifier quatre niveaux géomorphologiques (numérotés de 1 à 4) à partir du niveau de base (la dépression fermée, le niveau 0).Nous avons réalisé pour cette étude neuf profils et procédé à 30 prélèvements d'échantillons de sols dont 22 ont subit un traitement diffractométrique au rayons X.Dans chaque climat constant, chaque paysage engendre ses accumulations minérales selon la roche mère qui le constitue, et sur le plan géochimique les éléments issus de la dégradation des minéraux en amont sont reconstitués en aval. Dans le paysage saharien, les résultats analytiques et diffractométriques des échantillons des sols nous ont révélé une certaine rupture de ce schéma dû essentiellement au facteur éolien très caractéristique dans ces régions et aussi à la proximité de la nappe phréatique de la surface (niveau 1 et 2). En effet les résultats obtenus montrent que la distribution spatiale des sols est relativement bien liée à la position des unités géomorphologiques. Cela est particulièrement remarquable sur le niveau de base où l''accumulation salines particulièrement celle du gypse .est liée à la présence d'une nappe chargée en ions basiques qui agit sur certains minéraux secondaires comme précurseurs d'aggradation .et éventuellement de la néoformation de l'attapulgite. Par contre pour les niveaux 3 et 4 les minéraux identifiés sont quasiment issus d'héritages et d'apports latéraux. / In the run of this study, we have tried to highlight the outline of the spatial evolution of the soil characters in some soils on an established sequence on a geomorphological map, in the Valley of Oued Righ, area located in the Northern Sahara East of Algeria. We have thanks to a long survey selected an area on the northern edge of chott Mason and or we could identify 04 géomorphological levels (from 1 to 4) from the basic level (depression level, the o-level).We have carried out for this study 09 profiles and conducted 30 sampling of soils which 22 have underwent diffractometric treatment to the x-ray.In each constant climate, each landscape creates its mineral accumulations in the bedrock which is, and on the geochemical map from elements of the degradation of minerals in height area reconstituted in downstream. In the Saharan landscape, diffractometric of soil samples and analytical results we are revealed a break of this schema due mainly to the very characteristic wind factor in these regions and to the proximity of the groundwater to the surface (level 1 and 2) also. Indeed the results obtained show that the spatial distribution of soil is relatively tied to position units geomorphological responsible for accumulation of basic deposit salt especially of gypsum .This charged basic ion water is on secondary as precursors of aggradations .and minerals possibly neoformation of attapulgite. For levels 3 and 4 minerals identified are almost from inheritance and side intake.
93

Atributos químicos de um latossolo vermelho eutroférrico submetido a gessagem e cultivado com trigo e soja em semeadura direta / Change chemical latossolo vermelho eutroférrico submitted gypsum with soy and wheat no-tillage

Rampim, Leandro 23 March 2008 (has links)
Made available in DSpace on 2017-07-10T17:37:24Z (GMT). No. of bitstreams: 1 Leandro-Rampim.pdf: 366762 bytes, checksum: 5aa4ca621ef50368e9c462be07112b71 (MD5) Previous issue date: 2008-03-23 / Fundação Araucária / The presence of aluminum in the soil is one among the several existent problems that harm the growth, development and productivity in commercial cultures as soy and wheat principally when water deficit, once there is minor surface of roots for the absorption of water. Like this the influence of the use of the plaster was analyzed in the chemical characteristics of a Latossolo vermelho eutroférrico of loamy texture for the wheat cultures and soy, under system of direct planting. It took place collections of soil samples to the six and 12 months after application 0, 1, 2, 3, 4 e 5 t ha-1 of the gypsum to evaluate the tenors of Ca, Mg, K, exchangeable Al, pH, SB, V%, m% and tenor of S in the soil. For the wheat cultures and soy they were appraised the tenors of Ca, Mg, K, S, and Al in the tissue, mass of 1000 grains and productivity. The use of gypsum increased the tenors of Ca and S and it reduced Al's tenors, besides leaching Mg and K in the soil, increasing SB and V% in the deepest layers. In the tissue increased Ca and Mg for the soy and it reduced in the wheat, it increased the tenor of S in both cultures and K increased in a quadratic way for the culture of the soy. The found results show that the use of the plaster provided mobility of K+ and Mg2+ up to 40 cm of depth. The use of up to 5 t ha-1 of gypsum they resulted in increase of the tenors of Ca2+ and SO42 - in depth until one year after the application and the dose of 3 t ha-1 it provided larger reduction of exchangeable Al and also of the saturation for Al for Latossolo vermelho eutroférrico of loamy texture. In exchangeable Al's presence the use of the gypsum implicated in increase of the wheat productivity but it didn't influence the productivity of the soy / A presença de alumínio no solo é um entre os diversos fatores existentes que prejudicam o crescimento, desenvolvimento e produtividade de culturas comerciais como soja e trigo principalmente quando ocorre déficit hídrico, uma vez que há menor superfície de raízes para a absorção de água e nutrientes. Este trabalho avaliou a influência do uso do gesso nas características químicas de um Latossolo Vermelho eutroférrico de textura argilosa para as culturas de trigo e soja, sob sistema de plantio direto. Realizou-se coletas de amostras de solo aos seis e 12 meses após aplicação superficial de 0, 1, 2, 3, 4 e t ha-1 de gesso para avaliar os teores de Ca, Mg, K, Al trocáveis, pH, SB, V%, m% e teor de S no solo. Para as culturas de trigo e soja foram avaliados os teores de Ca, Mg, K, S, e Al no tecido foliar, massa de 1000 grãos e produtividade. O uso de gesso aumentou os teores de Ca e S e reduziu os teores de Al, além de lixiviar Mg e K no solo, aumentando a SB e V% nas camadas mais profundas. No tecido foliar aumentou Ca e Mg para a soja e reduziu no trigo, aumentou o teor de S em ambas culturas e o K aumentou de forma quadrática para a cultura da soja. Os resultados encontrados mostram que o uso do gesso proporcionou mobilidade de K+ e Mg2+ até 40 cm de profundidade. O uso de até 5000 kg ha-1 de gesso resultaram em aumento dos teores de Ca2+ e SO42- em profundidade até um ano após a aplicação sendo que a dose de 3 t ha-1 proporcionou maior redução do Al trocável e também da saturação por Al para o Latossolo Vermelho eutroférrico de textura argilosa. Na presença de Al trocável o uso do gesso implicou em aumento da produtividade de trigo mas não influenciou a produtividade da soja
94

Influence of the SO<sub>3</sub> Content of Cement on the Durability and Strength of Concrete Exposed to Sodium Sulfate Environment

Hanhan, Amin A 05 November 2004 (has links)
The objective of this investigation was to assess the influence of the SO3 content on the durability and strength of portland cement. Four portland cements were used in this study. The cements had a variable tricalcium silicate, tricalcium aluminate, and alkali contents, as well as differences in the amount and form of calcium sulfates. The SO3 content of the cements was increased by replacing part of the cement by gypsum according to ASTM C 452-95. Mortar bars and cubes were prepared for the as-received as well as for the cements with an SO3 content of 3.0% and 3.6%. The durability of the as-received and doped cements was determined by measuring the length change of the mortar bars that were exposed to sodium sulfate environment. The compressive strength of the mortar cubes prepared for the same mixes was measured at different ages for sets of cubes cured both in sodium sulfate solution and in saturated lime solution. It was concluded at the end of this study that there is an optimum SO3 content for the lowest expansion that is different from that determined for the highest compressive strength. Optimum values also differed from one cement to another and from one age to another for the same cement. The results also indicate the dependence of SO3 content on tricalcium aluminate and alkali content of cements. In addition, for all cements examined in this study with alkali content of less than 0.60%, increasing the SO3 content above 3.0% had negative effects on durability assessed by strength or expansion measurements. For the cement with highest alkali and tricalcium aluminate content, increasing the SO3 content from 3.0% to 3.6% delayed the onset of strength drop; however, at 360 days the strength drop experienced by both doping levels was the same.
95

Removal of sulphates from South African mine water using coal fly ash

Godfrey Madzivire January 2009 (has links)
<p>This study evaluated SO4 2- removal from circumneutral mine water (CMW) collected from Middleburg coal mine using coal FA collected from Hendrina power station. The following parameters were investigated: the effect of the amount of FA, the effect of the final pH achieved during treatment, the effect of the initial pH of the mine water and the effect of Fe and Al on SO4 2- removal from mine water. The precipitation of ettringite at alkaline pH was evaluated to further reduce the SO4 2- concentration to below the DWAF limit for potable water. Removal of SO4 2- from mine water was found to be dependent on: the final pH achieved during treatment, the amount of FA used to treat the mine water and the presence of Fe and Al in the mine water. Treatment of CMW using different CMW:FA ratios / 5:1, 4:1, 3:1, and 2:1 resulted in 55, 60, 70 and 71 % SO4 2- removal respectively. Treatment of CMW to pH 8.98, 9.88, 10.21, 10.96, 11.77 and 12.35 resulted in 6, 19, 37, 45, 63 and 71 % SO4 2- removal respectively. When the CMW was modified by adding Fe and Al by mixing with Navigation coal mine AMD and treated to pH 10, 93 % SO4 2- removal was observed. Further studies were done to evaluate the effects of Fe and Al separately. Treatment of simulated Fe containing AMD (Fe-AMD) to pH 9.54, 10.2, 11.8, and 12.1 resulted in 47, 52, 65, and 68 % SO4 2- removal respectively. When Al containing AMD was treated to pH 9.46, 10.3, 11.5 and 12 percentage SO4 2- removal of 39, 51, 55 and 67 % was observed respectively.</p>
96

Gypsum Wallboard: A Study Examining Wallboard Waste Management Options for Southern Ontario

van de Merwe, Susan January 2009 (has links)
In 2005, the Recycling Council of Ontario published a report that identified the construction industry as one sector that did not manage its waste in an environmentally appropriate manner. In this report, Let’s Climb Another Molehill, 15 case studies were executed to understand why this industry was neither handling nor disposing its waste properly in Southern Ontario. A set of generic recommendations was generated to help improve the management of this industry’s waste. Unfortunately the scope of the report was too broad to support conclusions about the management of specific types of problematic construction waste. The aim of this thesis is to narrow what was done in Let’s Climb Another Molehill to focus only on gypsum wallboard. The purpose of this research is to determine what options are the most desirable and feasible to deal sustainably with gypsum wallboard waste in Southern Ontario, both now and in the future. All recommendations offered are case specific. A number of methods have been utilized to obtain the information needed to formulate appropriate recommendations to deal with wallboard. Information learned through the literature, witnessed through the observation sessions, and acquired through the interviews led to two unique option categories: 1) alternative materials and 2) change in practices. To evaluate these options, a set of criteria was created based on the concepts of sustainability and integrated waste management (IWM). This sustainable IWM criteria set allowed for consistent evaluation of the options. To improve the recommendations, the sustainable IWM criteria were refined to better deal with each of the two categories of options. When the sustainable IWM criteria for evaluating alternative materials were applied, gypsum wallboard was found still to be the best interior wall material to use today. However, applying the sustainable IWM criteria for evaluating change in practices showed that the problem with using this product lies with its management and, therefore, the remaining recommendations focus on improving the creation, use and disposal of wallboard. Many of these recommendations can easily be adopted to help eliminate inappropriate wallboard management practices. This research was able to identify areas where problems arose and to offer feasible options to improve environmentally inappropriate behaviors associated with wallboard management. Although numerous recommendations are offered, the three fundamental recommendations that will lead to the biggest change include: 1) greater number of educational programs devoted to the construction industry; 2) stricter regulations and better enforcement; and 3) a dramatic increase in landfill tipping fees. If these three recommendations were implemented, it is believed that they will play a positive role in managing gypsum wallboard waste in a more sustainable manner.
97

Gypsum Wallboard: A Study Examining Wallboard Waste Management Options for Southern Ontario

van de Merwe, Susan January 2009 (has links)
In 2005, the Recycling Council of Ontario published a report that identified the construction industry as one sector that did not manage its waste in an environmentally appropriate manner. In this report, Let’s Climb Another Molehill, 15 case studies were executed to understand why this industry was neither handling nor disposing its waste properly in Southern Ontario. A set of generic recommendations was generated to help improve the management of this industry’s waste. Unfortunately the scope of the report was too broad to support conclusions about the management of specific types of problematic construction waste. The aim of this thesis is to narrow what was done in Let’s Climb Another Molehill to focus only on gypsum wallboard. The purpose of this research is to determine what options are the most desirable and feasible to deal sustainably with gypsum wallboard waste in Southern Ontario, both now and in the future. All recommendations offered are case specific. A number of methods have been utilized to obtain the information needed to formulate appropriate recommendations to deal with wallboard. Information learned through the literature, witnessed through the observation sessions, and acquired through the interviews led to two unique option categories: 1) alternative materials and 2) change in practices. To evaluate these options, a set of criteria was created based on the concepts of sustainability and integrated waste management (IWM). This sustainable IWM criteria set allowed for consistent evaluation of the options. To improve the recommendations, the sustainable IWM criteria were refined to better deal with each of the two categories of options. When the sustainable IWM criteria for evaluating alternative materials were applied, gypsum wallboard was found still to be the best interior wall material to use today. However, applying the sustainable IWM criteria for evaluating change in practices showed that the problem with using this product lies with its management and, therefore, the remaining recommendations focus on improving the creation, use and disposal of wallboard. Many of these recommendations can easily be adopted to help eliminate inappropriate wallboard management practices. This research was able to identify areas where problems arose and to offer feasible options to improve environmentally inappropriate behaviors associated with wallboard management. Although numerous recommendations are offered, the three fundamental recommendations that will lead to the biggest change include: 1) greater number of educational programs devoted to the construction industry; 2) stricter regulations and better enforcement; and 3) a dramatic increase in landfill tipping fees. If these three recommendations were implemented, it is believed that they will play a positive role in managing gypsum wallboard waste in a more sustainable manner.
98

Mineralogical And Geochemical Properties Of Messinian Gypsum Occurence In Polatli Sazilar Region, Ankara

Cakmak, Hayriye 01 December 2008 (has links) (PDF)
The objective of this study is to understand the petrographical, mineralogical and geochemical characteristics of Messinian (Upper Miocene) gypsum occurence in Polatli Sazilar region, Ankara and to determine the impurities associated with gypsum. Moreover, it is aimed to interpret the usability of this raw material with impurities in plaster and plasterboard production based on industrial standards. Based on petrographical study, the first variety of gypsum which have different physical properties is white massive, micro crystalline, and translucent gypsum. Prismatic, transparent, idiomorphic and cleavage dominated selenite is the second variety. The gypsum rock is also identified that it is composed of sand sized selenite crystals and gypsum grains in a calcite and clay rich matrix. These impurity minerals also observed in thin beds alternating with gypsum. Scanning electron microscopic (SEM) studies are conducted to determine the relationship between the impurity mineral, gypsum and the selenite. X-ray diffractometry (XRD) studies were used to identify the type of clay minerals. In the samples, Ca-smectite is the essential impurity clay mineral. Rarely, mixed layer of illite-smectite is also identified. Geochemical studies also shows that as the amount of clay impurity increases, MgO, Al2O3, Fe2O3, Na2O, K2O (wt%) increases with decreasing SO3 (wt%). On the other hand, impurity of calcite controls the CaO (wt%) content in varying amounts. Five different groups of samples indicating different abundance of clay and calcite impurities are interpreted. The clay rich samples are enriched, in general, in vanadium, nickel, copper and chromium.
99

Effects Of Pozzolan Incorporation And Curing Conditions On Strength And Water Resistance Of Natural Gypsum Pastes

Cengiz, Okan 01 September 2009 (has links) (PDF)
ABSTRACT EFFECTS OF POZZOLAN INCORPORATION AND CURING CONDITIONS ON STRENGTH AND WATER RESISTANCE OF NATURAL GYPSUM PASTES Cengiz, Okan Ph.D., Department of Civil Engineering Supervisor : Prof. Dr. Turhan Y. Erdogan September 2009, 189 pages There are large reserves of gypsum rock (CaSO4&middot / 2H2O) in Turkey and in various regions of the world. Heating gypsum rock to 140 - 190 0C causes it to lose three-fourths of its water molecules and turn into gypsum, called plaster of Paris / heat application over 190 0C results in loss of all the water molecules and this form of the material is called gypsum anhydrite. When gypsum is mixed with water, it gains cementitious property and hardens in a short time. Therefore, natural gypsum anhydrite and especially plaster of Paris are widely used in the construction industry. On the other hand, its not being water resistant and having low strength restrict the use of gypsum products for outdoor applications. In this study, the effects of pozzolan incorporation to natural gypsum pastes and application of various curing regimes for improving their water resistance and strength were investigated. Compressive strength and absorption tests on one thousand one hundred twenty two 5-cm cube specimens produced from v 13 different mixture types were conducted. Also the microstructures of these products were investigated using the analytical technique X-Ray Diffraction. The test results showed that water resistance and strength properties of pozzolan-incorporated gypsum products were improved. Curing of the product at elevated temperature regimes was an additional factor that contributed to this improvement. It was concluded that the natural gypsum mixtures prepared and cured at the above-mentioned conditions could also be used for outdoor applications. Keywords: Pozzolan, Natural Gypsum, Elevated Temperature Curing
100

Study of CaSO₃·1/2H₂O nucleation and growth rates in simulated flue-gas desulfurization liquors

Kelly, Brian John, 1956-1983 January 1983 (has links)
No description available.

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