The use of cement in the building industry accounts for a large part of the world's CO2-emissions. In the developing part of the world where materials are costly and labour is cheap, cement is expensive. In Nepal, a country which is frequently hit by earthquakes, low-cement-content building blocks are already being made and research on how to reduce the cement content further is currently going on. The manufacturing process for these blocks varies significantly, so a method to predict block strength easily and implement cost-effective quality control could substantially enhance production quality. The purpose of this study is to investigate how to predict the strength of building blocks using the water content, cement content and bulk density. Additionally, it examines whether bulk density could serve as a reliable indicator of strength, which could simplify quality control by allowing blocks to be weighed. This, together with an evaluation of the production site performance, is used to calculate the theoretical improvement potential and a proposed cement reduction. Through experiments, the compressive strength was measured for blocks of mixes with different cement percentages under various water content conditions, resulting in blocks with differing bulk densities. This data was used to create a model that predicts the compressive strength. Field visits to five sites were conducted to evaluate the current performance and this data was used to calculate the improvement potential. The results show the importance of water for the workability of the mix and in turn the compressive strength of the blocks. More water and more material into the mold lead to an increase in the strength and the theoretical improvement potential for cement reduction is 50\% by only these measures. The bulk density is a promising indicator of the compaction and compressive strength and weighing the blocks at creation could potentially reduce the variability in the strength of the blocks.

Made available in DSpace on 2017-07-25T19:30:02Z (GMT). No. of bitstreams: 1 Andre Carlos Auler.pdf: 1218277 bytes, checksum: aedcd75095720ba4b41e7ad48e647731 (MD5) Previous issue date: 2014-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Liming is the practice used to correct soil acidity and its reaction is dependent on the mode of application of the lime. The addition of lime to the soil with the tilling is an alternative for increasing his reaction. However, tillage alters its structure and processes occurring in it. The aim of this study was to evaluate the influence of liming of liming in three modes of application of limestone (on the surface, incorporated with plowing and harrowing and subsoiling and disking) on the physico-hydrical attributes of a Dystrudept. For this, an experiment was installed in the field with banded design, with treatments in a factorial arrangement (3 × 2). Treatments formed from the combination of two rates of lime (0 and 15 Mg ha-1) and three modes of application of limestone (on the surface, incorporate with plowing and harrowing and subsoiling and harrowing). Undisturbed and disturbed soil samples were collected at 0-0.10 and 0.10-0.20 m layers between plant rows of corn 18 months after installation of the experiment. The water-dispersed clay (WDC), flocculation degree (FD), bulk density (BD), total porosity (TP), water retention curves, pore size distribution curve, particle size and soil chemical properties were determined order to diagnose the effects of liming the soil studied. Liming effects on the physico-hydrical attributes of the soil were restricted to 0-0.10 m layer. The WDC and the FD were influenced by tillage, but not by liming. When liming was performed on the surface, there was a reduction of the DB and increased TP. In all modes of application of limestone, liming increased water retention and altered the distribution of pores. To conclude, the changes in physico-hydrical attributes of the soil were mostly due to the increase of pH and replacement of aluminum by calcium and magnesium in the exchange complex. / A calagem é a prática empregada na correção da acidez do solo e sua reação depende do modo de aplicação do corretivo. A incorporação de calcário com o revolvimento do solo é uma alternativa para o aumento da reação. Porém, a mobilização do solo altera a sua estrutura e os processos que nela ocorrem. O objetivo deste trabalho foi avaliar a influência da calagem em três modos de aplicação do calcário (na superfície, incorporada com aração e gradagem e com subsolagem e gradagem) nos atributos físico-hídricos de um CAMBISSOLO HÁPLICO Alumínico. Para isso, instalou-se um experimento em campo com delineamento em faixas, com tratamentos em arranjo fatorial (3 × 2). Os tratamentos constituíam-se da combinação de duas doses de calcário (0 e 15 Mg ha-1) e três modos de aplicação do calcário (na superfície, incorporado com aração e gradagem e subsolagem e gradagem). Amostras indeformadas e deformadas de solo nas camadas 0-0,10 e 0,10-0,20 m foram coletadas nas entrelinhas da cultura do milho 18 meses após a instalação do experimento. Foram avaliados os teores de argila dispersa em água (ADA), grau de floculação (GF), densidade do solo (Ds), porosidade total (Pt), curvas de retenção de água, curva de distribuição de poros, granulometria e atributos químicos do solo. Os efeitos da calagem sobre os atributos físico-hídricos do solo foram restritos à camada 0-0,10 m. A ADA e o GF foram influenciados pelo modo de aplicação do calcário, mas não pela calagem. Quando a calagem foi realizada na superfície, ocorreu redução da DS e aumento da Pt. Em todos os modos de aplicação do calcário, a calagem aumentou a retenção de água e alterou a distribuição de poros. Concluiu-se que as alterações nos atributos físico-hídricos do solo foram em sua maioria decorrentes do aumento do pH e da substituição do alumínio por cálcio e magnésio no complexo de troca.

Submitted by Carla Ferreira (carlaferreira66@gmail.com) on 2014-07-30T15:25:52Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Efeitos_de_culturas_de_cobertura_na_qualidade_fisica_do_solo_sob_plantio_direto.PDF: 481433 bytes, checksum: 95bdb8ab9b60f7aec50abbdf26baae09 (MD5) / Made available in DSpace on 2014-07-30T15:25:52Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Efeitos_de_culturas_de_cobertura_na_qualidade_fisica_do_solo_sob_plantio_direto.PDF: 481433 bytes, checksum: 95bdb8ab9b60f7aec50abbdf26baae09 (MD5) Previous issue date: 2008-02-22 / The objective of this study was to verify the suitability of S index in the diagnostic of physical quality of Cerrado soils and, based upon it, to determine the effect of cover crop mulches on physical quality of a Dystrophic Red Latosol (Oxisol) under no-tillage. A total of 2364 samples were selected from the soil data base of Embrapa Rice & Beans and Embrapa Cerrados, covering Cerrado soils from Mid-West, North, and Northeast regions of Brazil. Values of S index, defined as the slope of the soil water retention curve at its inflection point, obtained from these samples were correlated to soil bulk density, macroporosity, and total porosity, considering the following textural classes: very clayey, clayey, sandy clay, sandy clay loam, loam/sandy loam e loamy sand/sand. Based on review of literature, critical values were established for the physical attributes that separated, according to the texture, soils with good and poor structural quality and, based upon they, critical values were established for the S index. In order to study the effect of cover crop mulches on soil physical quality, an experiment was carried out under center pivot at Embrapa Rice & Beans, in Santo Antônio de Goiás, GO, in a randomized block design, with eight replications. The treatments consisted of eight cover crops: Brachiaria brizantha; corn associated with B. brizantha; pigeon pea; millet; Panicum maximum; sorghum; Stylosanthes guianensis; and Crotalaria juncea. The first seven crops had been cultivated in summer season since December 2001 and C. juncea since November 2003. In the winter season, after cover crop desiccation, irrigated common bean crop was implemented under no-tillage. In February 2006, soil organic matter content, some soil physical attributes, and soil physical quality measured by S index were determined. This index was highly correlated to the physical attributes, showing to be an adequate indicator of physical quality of Cerrado soils. The limit value of S = 0.045 showed to be adequate to separate soils with good structure and soils with the tendency to be degraded, while values of S ≤ 0,025 indicate physically degraded soils. Cover crops, specially grasses, favored soil aggregation at surface layer. Soil cultivation modified its structure in comparison to native forest, increasing bulk density and reducing macroporosity and total porosity, and hence, reducing soil physical quality. Among the cover crops, pigeon pea, C. juncea, and corn associated with B. brizantha were those that maintained soil surface layer with good physical quality. / Os objetivos desse trabalho foram verificar a adequação do índice S no diagnóstico da qualidade física de solos de Cerrado e, com base nele, determinar o efeito de culturas de cobertura na qualidade física de um Latossolo Vermelho distrófico sob plantio direto. Foram selecionadas, nos bancos de dados dos Laboratórios de Solo das Embrapa Arroz e Feijão e Embrapa Cerrados, 2364 amostras abrangendo solos sob Cerrado das regiões CO, N e NE do Brasil. Valores de índice S, definido como sendo a declividade da curva característica de retenção da água do solo em seu ponto de inflexão, foram correlacionados com a densidade do solo, macroporosidade e porosidade total, considerando as classes texturais: muito argilosa, argilosa, argilo-arenosa, franco-argiloarenosa, franco/franco-arenosa e areia-franca/arenosa. Foram buscados na literatura valores limites de atributos físicos que separavam, de acordo com a textura, solos com boa e pobre qualidade estrutural e, com base neles, estabelecido valores limites para o índice S. Para o estudo do efeito de culturas de cobertura na qualidade física do solo, foi conduzido um experimento sob pivô central na Embrapa Arroz e Feijão, em Santo Antônio de Goiás, GO, no delineamento de blocos ao acaso, com oito repetições. Os tratamentos consistiram de oito culturas de cobertura: braquiária; milho consorciado com braquiária; guandu anão; milheto; mombaça; sorgo; estilosantes; e crotalária. As sete primeiras vêm sendo cultivadas no verão desde dezembro de 2001 e a crotalária a partir de novembro de 2003. No inverno de cada ano, após dessecação dessas culturas, foi implantado o feijoeiro irrigado. Em fevereiro de 2006 foram determinados o conteúdo de matéria orgânica do solo, alguns atributos físicos, e a sua qualidade física por meio do índice S. Esse índice correlacionou-se altamente com os atributos físicos, mostrando ser um adequado indicador da qualidade física de solos de Cerrado. O valor limite de S = 0,045 mostrou-se adequado à divisão entre solos de boa qualidade estrutural e solos com tendência a se tornar degradados, enquanto valores de S ? 0,025 indicam solos degradados fisicamente. As culturas de cobertura, especialmente as gramíneas, favoreceram a agregação do solo na camada superficial. O cultivo do solo modificou a sua estrutura comparativamente à mata nativa, aumentando sua densidade e reduzindo a macroporosidade, porosidade total e, consequentemente, a sua qualidade física. Entre as culturas de cobertura, guandu, crotalária e milho consorciado com braquiária foram as que mantiveram a camada superficial do solo com boa qualidade física.

Nous avons étudié la conductivité thermique de particules de silice mésoporeuse organisée de type SBA-15 de morphologie bâtonnet et présentant trois états d’agrégation : non agrégées (morphologie A), agrégées en macrostructures fibreuses homogènes en taille (morphologie B) et agrégées en macrostructures fibreuses hétérogènes en taille (morphologie C). Ces trois types de morphologie ont subi un traitement thermique post-synthèse à des températures variables allant de 150 °C jusqu’à 900 °C. Les mesures de conductivité thermique ont été effectuées sur ces trois morphologies. Il s’est avéré que la morphologie B est la plus isolante par rapport aux deux autres morphologies. De plus, le traitement thermique post-synthèse à 300 °C est optimal pour avoir des caractéristiques texturales très importantes, ainsi qu’une meilleure performance en isolation thermique (23 mW.m-1.K-1 pour la poudre, 30 mW.m-1.K-1 pour le monolithe). Dans le cas de la morphologie B, nous avons modifié l’interconnexion entre les mésopores cylindriques réguliers qui caractérisent la SBA-15; soit la présence ou non de microporosité, voire de mésoporosité, en variant la température de l’étape de synthèse dite de vieillissement de 36 à 130 °C. Il apparait que la température de vieillissement à 130 °C améliore la performance d’isolation thermique (22 mW.m-1.K-1). Des pastilles de la SBA-15 de morphologie B en été élaborées par ajout de liants de deux types : organique avec la carboxyméthylcellulose, et inorganique avec une silice colloïdale. En ajoutant ces deux types de liants, les propriétés mécaniques sont un peu améliorées, cependant la performance d’isolation thermique diminue notablement. / We have studied the thermal conductivity of rod-shaped particles of ordered mesoporous silica (OMS) SBA-15 type with three states of aggregation: non aggregated (morphology A), aggregated in fibrous macrostructures homogeneous in size (morphology B) and aggregated in fibrous macrostructures heterogeneous in size (morphology C). These three types of morphology were heat treated at temperatures from 150 °C to 900 °C. The thermal conductivity measurements were performed on these three morphologies in powder form or monoliths (assembly of particles or aggregates). It has been found that the morphology B is more insulating compared to the two other morphologies. In addition, the post-synthesis heat treatment at 300 °C is optimum for obtaining important textural characteristics (specific surface area and pore volume), and a better thermal insulation performance (23 mW.m-1 K-1. for the powder and 30 mW.m-1.K-1 for the monolith). For morphology B, we have changed the interconnection between regular cylindrical mesopores of SBA-15 by varying the synthesis temperature during the aging step from 36 to 130 °C. It appears that the aging temperature at 130 °C, where the connection between the cylindrical mesopores is realized by mesopores, improves the performance of thermal insulation (22 mW.m-1.K-1). Monoliths of OMS SBA-15 type with morphology B were prepared by adding two kinds of binders: organic with carboxymethylcellulose (CMC), and inorganic with a colloidal silica (Ludox AS40). By adding these two kinds of binders, the mechanical properties of the SBA-15 with morphology B are improved, but the thermal insulation performance decreases considerably.

This study reports forest structure, regeneration and the soil properties from unlogged and logged forest in the Bulungan Research Forest, Malinau District, East Kalimantan, Indonesia. Four sites were compared by using four 1-ha replicate plots in each of primary forest (PF), 5, 10 and 30-yr old logged forest (LF-5, LF-10, LF- 30). The tree species composition differ among forest types, as it was shown that the mean value of similarity indices for all pairs were 0.215 (for the Jaccard index) and 0.353 (for the Sorensen index). The low values for similarities among forest types were most probably caused by low numbers of species shared between each forest type. Both correlation values, r = 0.023 for Jaccard index and r = 0.031 for Sorensen index, showed no strong correlation between the similarity index (C) and the distance between forest types. This supports the use of a chronosequence approach. A total of 914 tree species with ³ 10 cm dbh were recorded from 223 genera and 65 families. There were no significant differences in mean species numbers (166 – 180/ha) among treatments. Mean density of species was lower in LF-5 and LF-10 (501/ha) than in PF or LF-30 (605/ha and 577/ha); similarly to mean basal area (LF-5, 28.5 m2/ha; LF-10, 32.6 m2/ha) vs. PF (45.8 m2/ha) and LF-30 (46.9 m2/ha). Dead wood on the forest floor was significantly higher in LF-10 (75 m3/ha) than in the other treatments. Seedlings (< 2 cm dbh) of 1,022 species were recorded from 408 genera and 111 families. The mean number of tree seedling species ranged between 170-206; the mean density of seedlings was about two-fold lower in LF-10 (2790/ha) than in the other treatments. Saplings (>2 – 9.9 cm dbh) of 802 species belonged to 241 genera and 65 families. There was a high variability in species richness across treatments (89 – 191/ha), but not in stem numbers. The Dipterocarpaceae family was dominant in all treatments, followed by the Euphorbiaceae. The soils were acidic, low in nutrients and had low to very low fertility. Both primary and logged forest areas are marginal or not suitable for sustained production of plantation crops. Logging caused soil compaction in LF-30. Although in terms of number of species and trees, amount of BA, number of saplings and seedlings LF-30 appeared to have satisfied prescriptions for a second harvest, ecologically the forest is far from mature. The Indonesian Selective Cutting and Replanting (TPTI) system may need to be revised to a 35 – 45 year cycle to ensure long-term forest productivity in terms of not only timber but other goods and ecosystem services, the value of which are never quantified in monetary terms, but can be higher than the timber revenue.

From the Proceedings of the 1973 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - May 4-5, 1973, Tucson, Arizona / An infiltration- wetting agent study, using the wetting agent "WATER-IN", was conducted in the ponderosa pine forest type of east central Arizona. An application rate of 10 gallons of wetting agent per acre was used on bare mineral soil and on ponderosa pine litter. The infiltration rate was measured by a modified North Fork infiltrometer. It was found that "WATER-IN" significantly increased water runoff when applied to litter, but, when applied to bare mineral soil, "WATER-IN" caused a significant increase in water infiltration. The wetting agent did not significantly affect antecedent moisture, soil particle distribution, litter water holding capacity, or litter bulk density. It is presently hypothesized that the increase in water infiltration on treated bare mineral soil is due to a decrease in the average bulk density of the surface inch of soil. The increase in runoff when litter is treated is probably due to an interaction, either physical, chemical, or both, between the humus layer and "WATER-IN ", creating a hydrophobic condition where one did not exist before.

Darbo objektas – Eglės žievė paimta iš lentpjūvių ir biokuro sandėliavimo vietų. Darbo tikslas – Nustatyti eglės žievės, skirtos kūrenti šildymo katilines, masės ir tūrio kitimo dėsningumus. Darbo metodai – Empirinio tyrimo metodas paremtas duomenų rinkimu – parenkant mėginius, sveriant medienos žievę ir ją džiovinant. Kiekybinis palyginimas - statistinis duomenų apdorojimas paremtas dispersine ir regresine analize. Visą tiriamąją medžiagą sudarė 68 mėginiai paimti iš lentpjūvių ir biokuro sandėliavimo vietų, o gautų rezultatų palyginimui buvo paimti duomenys iš UAB ,,Vilniaus energijos“ žaliavų apskaitos duomenų bazės (98 mėginiai). Vertinant susidariusios žievės kiekį ir jos energetinę vertę buvo pasinaudota Lietuvos nepriklausomų medienos matuotojų asociacijos duomenų baze. Darbo rezultatai – Iš surinktų duomenų buvo nustatyta, kad didžiausias santykinis medienos žievės drėgnis lentpjūvėse yra lapkričio – sausio mėnesiais (55,5 – 62,62 %), o pagal ,,Vilniaus energija“ pateiktus duomenis lapkričio – kovo mėnesiais (56,35 – 60,62 %). Pavasarį medienai pradėjus džiūti, drėgmė išgaruoja, vandens kiekis medienoje pradeda mažėti. Mažiausias žievės drėgnis lentpjūvėse vasaros laikotarpiu yra birželio – rugsėjo mėnesiais (45 – 46 %), o pagal ,,Vilniaus energija“ pateiktus duomenis mažiausias žievės drėgnis būna gegužės – rugsėjo mėnesiais (35,66 – 40,42 %). Standartinė lentpjūvėse svyruoja nuo 0,45 iki 1,53 %, o pagal ,,Vilniaus energija“ duomenis nuo 0,71 iki 5,4 %. Įdomu tai... [toliau žr. visą tekstą] / The Object of work – The Spruce bark taken from sawmills and biofuel storage places. The aim of the work – To determine the Spruce, used for burning boiler plants, bark wheight and dencity change regularities. The methods of work – The method is based on data collection – choosing the samples, drying and weighing a timber bark. Quantitative comparison – statistical data treatment in a variance and regression analysis. The investigated material were 68 samples, taken from sawmills and biofuel storage places. To compare the results data were taken from ,,Vilniaus energijos“ (limited liability company ) material accounting data base ( 98 samples). In assessing the amount of the bark and its energy value was used Independent Lithuanian Timber Measurers Association database. The results – The results shows that the biggest relative timber bark humidity in a sawmills is between November – January (55,5 – 62,62 %), according to the data from „Vilniaus energija“ November – March (56,35 – 60,62 %). In spring a timber starts to dry, the humidity level decreases, water amount in a timber starts to decrease. The lowest humidity in a sawmills is in summer between June – September (45 – 46 %), according to ,,Vilniaus energija“ data, the lowest bark humidity is between May - September (35,66 – 40,42 %). Standard humidity deflection in the sawmills varies from 0,45 to 1,53 %, according to ,,Vilniaus energija“ data, standard humidity deflection varies from 0,71 to 5,4 %... [to full text]

Nowadays trend in Europe is returning to harvesting of traditional feeding crops. One of these crops is oat which has been universally used since time immemorial. Even today oats are processing and using in food industry and as a feed for farm animals. Further using of oats is in cosmetics and pharmaceutical industry. Oats contain high amount of proteins and fats, beta-glukan and mineral elements. Oats include vitamins B and E, lecitin, niacin and antioxidants. Research was executing on fields of University of South Bohemia in České Budějovice during one year. An impact on crop yield and quality of oats was observed in dissertation. There were used three crops corn, rape and cereal (spring wheat) in research. After these crops were sown ten varieties of oats, four naked and six husked varieties. At these varieties were observed an impact on crop yield and quality of oats. Evaluated characters were monitored during the vegetation, pre-harvest and post-harvest. There were observed germination and methane, height of vegetation, the degree of lodging oats, the number of lat m2, weeds, diseases and pests, after harvest was determine harvested grain yield, moisture and density, number of grains per panicle, thousand grain weight and grain on a network share during the vegetation. From the measured values follows that the best crop in year 2012 was corn and the best results were achieved by variety Abel, Avenuda, Atego, Pogon, Salo.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Soil management systems with minimum tillage and mulch are predominant in agriculture of Southern of Brazil. No-tillage for tobacco crop is not common and restricted to isolated places and only for some farmers that, through empiric tests and adaptation of equipments, search for soil preservation and increased yield. The objective of this work was study the main soil management systems for tobacco crop and possibilities of changing the traditional system of tobacco cropping, with emphasis on practices of soil management and conservation to maintain the levels of yield and decrease the environmental impacts. Six treatments, in a completely randomized blocks design with three replicates, were installed: PC conventional till; CMP - minimum tillage rest; CMA - minimum tillage oat; PDcC no-tillage with camalhão; PDcCC no-tillage with consolidated camalhão; PDsC no-tillage without camalhão. The experiment was installed in a watershed, located in Agudo-RS city, in the agricultural year of 2004, in a Leptosol. The maim physical parameters were soil moisture, measured with a time domain reflectometer (TDR), in the depths of 0-0,06, 0,06-0,12 and 0,12-0,18 m, and soil temperature in the depth of 0,05 m, measured with datalogger and termopars, both during 87 days in the growth cycle; total porosity, macroporosity, microporosity, bulk density and soil water retention curve (CRA), determined in the depths of 0-0,06, 0,06-0,12, 0,12-0,18 and 0,18-0,24 m, 30 days after transplantion (DAT) and on 135 DAT, except for CRA, in the depths of 0-0,06 and 0,06-0,12 m; water and soil loss by runoff, determined for eight rain events, in two blocks, with on area of 1.2 m2 of collection; potassium and phosphorus, soluble and total were determined for seven rain events; the root system, the distribution in the cultural profile, nutrients availability in the exploration area, dry mass for soil volume and maximum depth of roots were determined; mechanical resistance of soil was determined with a manual penetrometer to verify the depth of the root impediment; measures of the plants included the leaf area, determination of plant height, number of leaves and yield for hectare. The conservation managements reduced soil and water losses, providing smaller amplitude in the daily temperature variation, larges soil moisture, but the yield was smaller than PDsC. This result for the PDsC was directly influenced by the shallower roots depth, which was a consequence of several factors, such as: presence of impediment layer; absence of ridge; nutrients in the surface and favorable initial conditions of soil temperature and moisture. However, there was great interaction among factors, turning complex the explanation of the results obtained; therefore, factors such as nutrients in the surface favored the losses of P and K soluble, decreasing their availability to plants; the impediment layer reduced the volume of soil explored by the roots and the ability for water storage, whereas the management systems PDcCC and PDsC were outside the upper or lower limit of water availability, in the layer of 0 to 0,06 m, for about 15 days. / Sistemas de manejos do solo com o mínimo de revolvimento e com palha em superfície predominam na maioria dos cultivos agrícolas, no Sul do Brasil. A utilização do plantio direto na cultura do fumo está sendo iniciada, mas restrita a locais isolados e a alguns agricultores, que, via testes empíricos e adaptação de equipamentos, buscam preservar o solo e aumentar a produtividade. O objetivo deste trabalho foi estudar os principais sistemas de manejo do solo para a cultura do fumo e as possibilidades de mudança no sistema tradicional de cultivo de fumo, com ênfase às práticas de manejo e conservação do solo, mantendo os níveis de produtividade e diminuindo os impactos ambientais. O delineamento experimental foi blocos ao acaso com três repetições e seis tratamentos, sendo eles: PC - preparo convencional; CMP - cultivo mínimo pousio; CMA - cultivo mínimo aveia; PDcC - plantio direto com camalhão; PDcCC - plantio direto com camalhão consolidado; PDsC - plantio direto sem camalhão. O experimento foi implantado em uma microbacia hidrográfica, localizada no município de Agudo-RS, no ano agrícola de 2004, sobre em um Neossolo litólico eutrófico típico. Os principais avaliadores físicos foram umidade volumétrica do solo, medida com reflectômetro de domínio de tempo (TDR), nas profundidades de 0-0,06, 0,06-0,12 e 0,12-0,18 m, e temperatura do solo na profundidade de 0,05 m medida com datalogger e termopares, ambas durante 87 dias no período de crescimento; porosidade total, macroporosidade, microporosidade, densidade do solo e curva de retenção de água (CRA), realizadas nas profundidades de 0-0,06, 0,06-0,12, 0,12-0,18 e 0,18-0,24 m aos 30 dias após transplante (DAT) e aos 135 DAT, exceto CRA, nas profundidades de 0-0,06 e 0,06-0,12 m; perda de água e solo pelo escoamento superficial, determinados em oito chuvas, em dois blocos, com uma área de coleta de 1,2 m2; fósforo e potássio solúvel e total, em sete chuvas; no sistema radicular foram determinados a distribuição no perfil cultural, disponibilidade de nutrientes na região de exploração, massa seca por volume de solo e profundidade máxima das raízes; a resistência mecânica do solo determinada com um penetrômetro manual para diagnosticar a profundidade de impedimento radicular; medidas avaliadoras das plantas foram área foliar, comprimento de caule, número de folhas e produtividade por hectare. Os preparos conservacionistas reduziram as perdas de solo e água e proporcionaram uma menor amplitude na temperatura diária, maior umidade do solo, mas a produtividade no PDsC ficou aquém dos preparos convencionais. Esse resultado no PDsC foi diretamente influenciado pelo menor aprofundamento das raízes, sendo esse conseqüência de vários fatores como presença de camada de impedimento, não possuir camalhão, posicionamento mais superficial da adubação de base e condições iniciais favoráveis de temperatura e umidade do solo. Contudo, houve grande interação de fatores, tornando complexa a explicação do resultado obtido, pois fatores como a adubação superficial favoreceu as perdas de P e K solúvel, diminuindo a disponibilidade; a camada de impedimento diminuiu o volume de solo explorado pelas raízes e a capacidade de armazenamento de água, sendo que os manejos PDcCC e PDsC ficaram em torno de 15 dias fora da faixa de disponibilidade de água, na camada de 0 a 0,06 m.

[EN] This Thesis is focused on the development and implementation of efficient numerical methods for the acoustic modelling and design of noise control devices in the exhaust system of combustion engines. Special attention is paid to automotive perforated dissipative silencers, in which significant differences are likely to appear in their acoustic behaviour, depending on the temperature variations within the absorbent material. Also, material heterogeneities can alter the silencer attenuation performance. Therefore, numerical techniques considering all these features are required to guarantee the accuracy of the results. A literature review is carried out, mainly related to one-dimensional models, as well as to acoustic models for absorbent materials and perforated surfaces. However, plane wave model limitations make indispensable using alternative multidimensional methods. In addition, the possibility of using new acoustic elements is explored. These elements have as an objective being a potential alternative to the fibrous absorbent materials, which can have a negative impact on health. The Thesis considers the use of microperforated and sintered surfaces. The latter have, in some cases, a nearly constant acoustic impedance, whose value depends, among others, on the thickness and porosity of the plates. To avoid the limitations of plane wave models, a finite element (FE) approach is proposed for the acoustic analysis of dissipative silencers including a perforated duct with uniform axial mean flow and an outer chamber with a heterogeneous distribution of the absorbent material. On the other hand, property variations can be also produced by temperature gradients. In this case, a hybrid FE model has been derived for perforated dissipative silencers including: (1) Thermal gradients in the central duct and the chamber; (2) A perforated passage carrying non-uniform axial mean flow. A FE approach has been implemented to solve the pressure-based wave equation for a non-moving heterogeneous medium, associated with the chamber. Also, the governing equation in the central duct has been written and solved in terms of an acoustic velocity potential to allow the presence of an axially inhomogeneous flow. The coupling between both regions has been carried out by means of a perforated duct and its acoustic impedance, adapted here to include absorbent material heterogeneities and mean flow effects. It has been found that the presence of non-homogeneities can have a significant influence on the acoustic attenuation of a silencer and should be included in the theoretical models. Optimization techniques for industrial noise control devices are relevant, since they lead to the production of elements with better characteristics. Evolutionary algorithms are emergent techniques able to obtain a solution, even in those problems in which the traditional optimization have difficulties. Optimization techniques are combined with the FE method to achieve the maximum attenuation in the frequency range of interest. A multichamber silencer optimization problem is defined and several analyses are carried out to obtain the most suitable configuration for each application. Under certain assumptions of axial uniformity, several techniques have been considered to reduce the computational effort of a full 3D FE analysis for dissipative silencers with temperature gradients and mean flow. These are based on a decomposition of the acoustic field into transversal and axial modes within each silencer subdomain, and a matching procedure of the modal expansions at the silencer area changes through the continuity conditions of the acoustic fields. The relative computational efficiency and accuracy of predictions for the matching techniques are studied, including point collocation at nodes and Gauss points and also mode-matching with weighted integration. All of them provide accurate predictions of the attenuation and improve the computational cost of a FE calculation / [ES] Esta Tesis se centra en el desarrollo e implementación de métodos numéricos eficientes para el diseño y modelado de componentes de la línea de escape en motores de combustión interna. Merecen especial atención los silenciadores disipativos perforados de automóviles, ya que su comportamiento acústico puede sufrir variaciones importantes debidas a las variaciones de temperatura en el material absorbente, así como a las heterogeneidades de la fibra. Por tanto, se requieren técnicas numéricas que consideren estos casos para garantizar la precisión de los resultados. Se lleva a cabo una revisión bibliográfica que recoge los modelos de onda unidimensionales, así como modelos acústicos de materiales absorbentes y superficies perforadas. Sin embargo, las limitaciones de los primeros hacen indispensable el uso de modelos multidimensionales. Además se explora la posibilidad de usar nuevos elementos acústicos, cuyo objetivo es ser una alternativa potencial a los materiales absorbentes, que pueden tener un efecto negativo sobre la salud. La Tesis considera el uso de superficies microperforadas y sinterizadas. Estas últimas en algunos casos presentan una impedancia casi constante, cuyo valor depende, entre otras cosas, del espesor y la porosidad de las placas. Para evitar las limitaciones de los modelos de onda plana, se propone un enfoque en elementos finitos (EF) para el análisis acústico de silenciadores disipativos que incluyen un conducto con flujo medio axial uniforme y una cámara externa con una distribución heterogénea de material absorbente. Por otro lado, la variación de las propiedades también puede producirse por gradientes térmicos. En este caso, se propone una formulación híbrida de EF para silenciadores disipativos perforados que incluye: (1) Gradientes térmicos en el conducto central y la cámara; (2) Un conducto perforado que canaliza flujo medio axial no uniforme. Se ha implementado una formulación de EF para resolver la ecuación de ondas en términos de presión para el medio estacionario heterogéneo asociado a la cámara. Además, la ecuación asociada al conducto central, expresada en términos de potencial de velocidad acústica, permite la presencia de flujo axial no uniforme. El acoplamiento entre ambas regiones se ha realizado mediante un conducto perforado y su impedancia acústica y se ha adaptado para incluir la citada falta de homogeneidad. Se ha visto que las heterogeneidades pueden influir notablemente en la atenuación acústica de un silenciador, debiéndose incluir en los modelos teóricos. Las técnicas de optimización para componentes industriales de control de ruido son importantes, ya que producen elementos con mejores características. Los algoritmos evolutivos son técnicas emergentes capaces de obtener una solución, incluso cuando la optimización tradicional tiene dificultades. Las técnicas de optimización se combinan con el MEF para conseguir la máxima atenuación posible en el rango de frecuencias de interés. Se ha definido un problema de optimización de un silenciador multicámara y se han llevado a cabo varios análisis para obtener la configuración más adecuada para cada caso. Bajo ciertas hipótesis de uniformidad axial, se han considerado varias técnicas para reducir el coste computacional de un análisis 3D completo para silenciadores disipativos con gradientes de temperatura y flujo medio. Éstas se basan en la descomposición del campo acústico en modos axiales y transversales dentro de cada subdominio, y un procedimiento de acoplamiento de las expansiones modales en los cambios de sección del silenciador mediante las condiciones de continuidad de los campos acústicos. Se estudia la eficiencia computacional y precisión de las predicciones de las técnicas de acoplamiento, incluyendo colocación puntual en nodos y puntos de Gauss, así como ajuste modal. Todos ellos proporcionan predicciones precisas de la atenuación mejorando el coste / [CAT] Aquesta Tesi es centra en el desenvolupament i implementació de mètodes numèrics eficients per al disseny i modelatge de components de la línia d'escapament en motors de combustió interna. Mereixen especial atenció els silenciadors dissipatius perforats d'automòbils, ja que el seu comportament acústic pot patir variacions importants degudes a les variacions de temperatura en el material absorbent, així com a les heterogeneïtats de la fibra. Per tant, es requereixen tècniques numèriques que considerin aquests casos per garantir la precisió dels resultats. Es porta a terme una revisió bibliogràfica que recull els models d'ona unidimensionals, així com models acústics de materials absorbents i superfícies perforades. No obstant això, les limitacions dels primers fan indispensable l'ús de models multidimensionals. A més s'explora la possibilitat d'usar nous elements acústics amb l'objectiu que siguen una alternativa potencial als materials absorbents, que poden tenir un efecte negatiu sobre la salut. La Tesi considera l'ús de superfícies microperforades i sinteritzades. Aquestes últimes en alguns casos presenten una impedància gairebé constant. El seu valor depèn, entre altres coses, del gruix i la porositat de les plaques. Per evitar les limitacions dels models d'ona plana, es proposa un enfocament amb elements finits (EF) per a l'anàlisi acústic de silenciadors dissipatius que inclouen un conducte amb flux mig axial uniforme i una càmera externa amb una distribució heterogènia de material absorbent. D'altra banda, la variació de les propietats també es pot produir per gradients tèrmics. En aquest cas, es proposa una formulació híbrida d'EF per silenciadors dissipatius perforats que inclou: (1) Gradients tèrmics en el conducte central i la càmera; (2) Un conducte perforat que canalitza flux mig axial no uniforme. S'ha implementat una formulació d'EF per resoldre l'equació d'ones en termes de pressió per al medi estacionari heterogeni associat a la càmera. A més, l'equació associada al conducte central, expressada en termes de potencial de velocitat acústica, permet la presència de flux axial no uniforme. L'acoblament entre les dues regions s'ha realitzat mitjançant un conducte perforat i la seva impedància acústica i s'ha adaptat per incloure la esmentada falta d'homogeneïtat. S'ha vist que les heterogeneïtats poden influir notablement en l'atenuació acústica d'un silenciador i s'han d'incloure en els models teòrics. Les tècniques d'optimització per a components industrials de control de soroll són importants, ja que produeixen elements amb millors característiques. Els algoritmes evolutius són tècniques emergents capaces d'obtenir una solució, fins i tot quan l'optimització tradicional té dificultats. Les tècniques d'optimització es combinen amb el mètode d'elements finits (MEF) per aconseguir la màxima atenuació possible en el rang de freqüències d'interès. S'ha definit un problema d'optimització d'un silenciador multicàmera i s'han dut a terme diverses anàlisis per obtenir la configuració més adequada per a cada cas. Sota certes hipòtesis d'uniformitat axial, s'han considerat diverses tècniques per reduir el cost computacional d'una anàlisi 3D complet per silenciadors dissipatius amb gradients de temperatura i flux mig. Aquestes es basen en la descomposició del camp acústic en modes axials i transversals dins de cada subdomini, i un procediment d'acoblament de les expansions modals en els canvis de secció del silenciador mitjançant les condicions de continuïtat dels camps acústics. S'estudia l'eficiència computacional i precisió de les prediccions de les tècniques d'acoblament, incloent col·locació puntual en nodes i punts de Gauss, així com ajust modal. Tots ells proporcionen prediccions precises de l'atenuació millorant el cost computacional d'EF. / Sánchez Orgaz, EM. (2016). Advanced numerical techniques for the acoustic modelling of materials and noise control devices in the exhaust system of internal combustion engines [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/64090 / TESIS