Qualidade física de um Latossolo Vermelho cultivado com soja submetido a níveis de compactação e de irrigação

Manter uma boa qualidade física do solo é importante para preservar o meio ambiente, além de maximizar a produtividade das plantas. Um solo compactado poderá interferir na densidade, na porosidade e na resistência do solo à penetração, influenciando no crescimento radicular. A presente pesquisa objetivou avaliar a qualidade física de um Latossolo Vermelho eutroférrico, textura argilosa, com a cultivar de soja CAC-1, submetido a quatro níveis de compactação e três níveis de irrigação, utilizando os atributos físicos do solo, assim como a correlação do sistema radicular com a produtividade da cultura. O delineamento experimental foi em blocos ao acaso, com parcelas subdivididas, com quatro repetições. Os níveis de compactação foram: C0 = 0, C2 = 2, C4 = 4 e C6 = 6 passadas, no mesmo local, de um trator de 11 t. Foram coletadas amostras indeformadas de solo nas entrelinhas da cultura da soja, para determinação dos atributos físicos, nas camadas de 0-0,10 e 0,10-0,20 m. A produtividade máxima da soja foi obtida com a resistência do solo à penetração de 0,71 MPa. O sistema radicular correlacionou-se inversamente com a produtividade da soja.

Comparação de penetrômetros na avaliação da compactação de latossolos

Diversos penetrômetros são utilizados para avaliar a resistência do solo à penetração em sistemas de uso e manejo, no entanto os valores obtidos com os mesmos divergem. O objetivo deste estudo foi comparar os resultados obtidos com três penetrômetros, em três níveis de compactação. Utilizou-se de um Latossolo Vermelho distrófico (LVd), textura média, e um Latossolo Vermelho eutroférrico (LVef), textura argilosa, cujas amostras foram coletadas na camada de 0-20 cm e compactadas em camadas, em vasos de 25 cm de diâmetro e 20 cm de altura. Determinou-se a resistência do solo à penetração com os penetrômetros de impacto, estático de anel dinamométrico e eletrônico de laboratório. em solo compactado, o penetrômetro de impacto apresentou valores superiores de resistência à penetração, comparado aos penetrômetros de anel dinamométrico e eletrônico, porém todos foram eficientes para caracterizar a compactação. Os resultados obtidos com os penetrômetros de anel dinamométrico e eletrônico foram semelhantes.

Estabilidade de agregados e resistência à penetração em Latossolos adubados por cinco anos com biossólido

O biossólido tem sido utilizado para fins agrícolas como fonte de nutrientes e condicionante dos atributos físicos do solo. Objetivou-se avaliar o efeito do biossólido na estabilidade de agregados e resistência à penetração de um Latossolo Vermelho distrófico textura média (LVd) e um Latossolo Vermelho eutroférrico argiloso (LVef), em Jaboticabal (SP). Utilizaram-se as doses de 0,0, 25,0, 47,5 e 50,0 Mg ha-1 de massa seca de biossólido que foi incorporado com grade até 0,1 m, antes da semeadura do milho. As amostras foram coletadas no quinto ano, após a colheita do milho, nas camadas de 0,0-0,1; 0,1-0,2; 0,2-0,3 m para determinação da composição granulométrica, matéria orgânica e estabilidade de agregados. A resistência do solo à penetração e umidade do solo foram determinadas até à profundidade de 0,4 m. O delineamento experimental foi de blocos ao acaso com cinco repetições. O diâmetro médio geométrico dos agregados foi maior na camada de 0,0-0,1 m e a partir da aplicação de 47,5 Mg ha-1 de biossólido nos dois solos. A aplicação de biossólido não influiu na resistência do solo à penetração, tampouco na umidade nos dois solos.

Estabilidade e robustez de um controlador adaptativo indireto por um modelo de referência e estrutura variável

In this thesis, it is developed the robustness and stability analysis of a variable structure model reference adaptive controller considering the presence of disturbances and unmodeled dynamics. The controller is applied to uncertain, monovariable, linear time-invariant plants with relative degree one, and its development is based on the indirect adaptive control. In the direct approach, well known in the literature, the switching laws are designed for the controller parameters. In the indirect one, they are designed for the plant parameters and, thus, the selection of the relays upper bounds becomes more intuitive, whereas they are related to physical parameters, which present uncertainties that can be known easier, such as resistances, capacitances, inertia moments and friction coefficients. Two versions for the controller algorithm with the stability analysis are presented. The global asymptotic stability with respect to a compact set is guaranteed for both cases. Simulation results under adverse operation conditions in order to verify the theoretical results and to show the performance and robustness of the proposed controller are showed. Moreover, for practical purposes, some simplifications on the original algorithm are developed

Uma abordagem indireta para o Controlador em Modo Dual Adaptativo Robusto

In this work is proposed an indirect approach to the DualMode Adaptive Robust Controller (DMARC), combining the typicals transient and robustness properties of Variable Structure Systems, more specifically of Variable Structure Model Reference Adaptive Controller (VS-MRAC), with a smooth control signal in steady-state, typical of conventional Adaptive Controllers, as Model Reference Adaptive Controller (MRAC). The goal is to provide a more intuitive controller design, based on physical plant parameters, as resistances, inertia moments, capacitances, etc. Furthermore, with the objective to follow the evolutionary line of direct controllers, it will be proposed an indirect version for the Binary Model Reference Adaptive Controller (B-MRAC), that was the first controller attemptting to act as MRAC as well as VS-MRAC, depending on a pre-defined fixed parameter

Qualidade da silagem de grão úmido em função da temperatura ambiente e pressão interna de armazenagem

Visando estabelecer a contribuição dos parâmetros físicos na qualidade final da silagem de grãos úmidos de milho, foi conduzido experimento, no interior de câmara climatizada, simulando cinco condições de temperatura ambiente (5ºC 24h-1 por dia; 25ºC 24h-1 por dia; 40ºC 24h-1 por dia; 20ºC 16h-1 por dia + 5ºC 8h-1 por dia; 30ºC 16h-1 por dia + 20ºC 8h-1 por dia) e duas condições de pressão no interior dos tambores de armazenagem (com e sem pressão interna). Para se determinar os efeitos sobre o grau de disponibilidade do amido na silagem pronta, procedeu-se a análises para avaliar a qualidade final da silagem (teor de umidade, pH, ácidos orgânicos, amido total e granulometria). O delineamento estatístico utilizado foi o inteiramente ao acaso, num fatorial 5 x 2, com três repetições. Os resultados obtidos indicaram influência significativa tanto da temperatura quanto da pressão, sendo os efeitos mais benéficos verificados nos tratamentos '30ºC 16h-1 por dia + 20ºC 8h-1 por dia', '25ºC 24h-1 por dia' e 'ausência de pressão'.

Caracterização de água produzida na indústria de petróleo para fins de descarte e otimização do processo de separação óleo/água

The oil industry has several segments that can impact the environment. Among these, produced water which has been highlight in the environmental problem because of the great volume generated and its toxic composition. Those waters are the major source of waste in the oil industry. The composition of the produced water is strongly dependent on the production field. A good example is the wastewater produced on a Petrobras operating unit of Rio Grande do Norte and Ceará (UO-RNCE). A single effluent treatment station (ETS) of this unit receives effluent from 48 wells (onshore and offshore), which leads a large fluctuations in the water quality that can become a complicating factor for future treatment processes. The present work aims to realize a diagnosis of a sample of produced water from the OU - RNCE in compliance to certain physical and physico-chemical parameters (chloride concentration, conductivity, dissolved oxygen, pH, TOG (oil & grease), nitrate concentration, turbidity, salinity and temperature). The analysis of the effluent is accomplished by means of a MP TROLL 9500 Multiparameter probe, a TOG/TPH Infracal from Wilks Enterprise Corp. - Model HATR - T (TOG) and a MD-31 condutivimeter of Digimed. Results were analyzed by univariated and multivariated analysis (principal component analysis) associated statistical control charts. The multivariate analysis showed a negative correlation between dissolved oxygen and turbidity (-0.55) and positive correlations between salinity and chloride (1), conductivity, chloride and salinity (0.70). Multivariated analysis showed there are seven principal components which can explain the variability of the parameters. The variables, salinity, conductivity and chloride were the most important variables, with, higher sampling variance. Statistical control charts have helped to establish a general trend between the physical and chemical evaluated parameters

Estudo de sistemas microemulsionados utilizando água do mar na recuperação avançada de petróleo

Petroleum exists in the nature in certain underground formations where it is adsorbed into the rocks pores. For the conventional recovery methods usually only 30% of the oil is extracted and this can be credited, basically, to three aspects: high viscosity of the oil, geology of the formation and high interfacial tensions between the reservoir s fluids. The enhanced recovery methods use the injection of a fluid or fluids mixture in a reservoir to act in points where the conventional process didn't reach the recovery rates. Microemulsion flooding, considered an enhanced method, has the purpose to desorb the oil from the rock formation and to attain an efficient displacement of the oil emulsion. With this in mind, this work was accomplished with two main objectives: the study of the parameters effect that influence a microemulsified system (surfactant and cosurfactant types, C/S rate and salinity) and the evaluation of displacement efficiency with the microemulsions that showed stability in the rich aqueous area. For the analyzed parameters it was chose the microemulsions composition used in the recovery stage: 25% water, 5% kerosene, 46.7% of butanol as cosurfactant and 23.3% of BC or SCO cosurfactant. The core plugs of Assu and Botucatu sandstones were appraised in porosity and permeability tests and then submitted to the steps of saturation with seawater and oil, conventional recovery with water and enhanced recovery with the selected microemulsions. The Botucatu sandstone presented better recovery parameters, and the microemulsion composed with BS surfactant had larger recovery efficiency (26.88%)

Avaliação e modelagem da absorção de H2S do gás natural em coluna de leito estagnado

Natural gas, although basically composed by light hydrocarbons, also presents contaminant gases in its composition, such as CO2 (carbon dioxide) and H2S (hydrogen sulfide). The H2S, which commonly occurs in oil and gas exploration and production activities, causes damages in oil and natural gas pipelines. Consequently, the removal of hydrogen sulfide gas will result in an important reduction in operating costs. Also, it is essential to consider the better quality of the oil to be processed in the refinery, thus resulting in benefits in economic, environmental and social areas. All this facts demonstrate the need for the development and improvement in hydrogen sulfide scavengers. Currently, the oil industry uses several processes for hydrogen sulfide removal from natural gas. However, these processes produce amine derivatives which can cause damage in distillation towers, can cause clogging of pipelines by formation of insoluble precipitates, and also produce residues with great environmental impact. Therefore, it is of great importance the obtaining of a stable system, in inorganic or organic reaction media, able to remove hydrogen sulfide without formation of by-products that can affect the quality and cost of natural gas processing, transport, and distribution steps. Seeking the study, evaluation and modeling of mass transfer and kinetics of hydrogen removal, in this study it was used an absorption column packed with Raschig rings, where the natural gas, with H2S as contaminant, passed through an aqueous solution of inorganic compounds as stagnant liquid, being this contaminant gas absorbed by the liquid phase. This absorption column was coupled with a H2S detection system, with interface with a computer. The data and the model equations were solved by the least squares method, modified by Levemberg-Marquardt. In this study, in addition to the water, it were used the following solutions: sodium hydroxide, potassium permanganate, ferric chloride, copper sulfate, zinc chloride, potassium chromate, and manganese sulfate, all at low concentrations (»10 ppm). These solutions were used looking for the evaluation of the interference between absorption physical and chemical parameters, or even to get a better mass transfer coefficient, as in mixing reactors and absorption columns operating in counterflow. In this context, the evaluation of H2S removal arises as a valuable procedure for the treatment of natural gas and destination of process by-products. The study of the obtained absorption curves makes possible to determine the mass transfer predominant stage in the involved processes, the mass transfer volumetric coefficients, and the equilibrium concentrations. It was also performed a kinetic study. The obtained results showed that the H2S removal kinetics is greater for NaOH. Considering that the study was performed at low concentrations of chemical reagents, it was possible to check the effect of secondary reactions in the other chemicals, especially in the case of KMnO4, which shows that your by-product, MnO2, acts in H2S absorption process. In addition, CuSO4 and FeCl3 also demonstrated to have good efficiency in H2S removal

Efeito da concentração do amido de milho na liberação de paracetamol de comprimidos

Este trabalho avaliou a influência da concentração de amido de milho nas características físicas e na liberação in vitro de paracetamol a partir de comprimidos. Os granulados foram analisados quanto à granulometria e densidades aparentes bruta e compactada e os comprimidos quanto ao peso médio, espessura, dureza, friabilidade, tempo de desintegração. Os comprimidos foram preparados a partir de granulados obtidos por granulação a úmido, utilizando cozimento de amido a 10% como agente granulante, segundo três formulações. Embora os comprimidos obtidos tenham apresentado características dentro dos limites farmacopéicos, os resultados indicam que variações da concentração de amido provocam diferenças nos diversos parâmetros físicos estudados. Concentração mais alta de amido em pó dá origem, provavelmente, à interação entre os componentes da fórmula, interferindo na liberação in vitro do fármaco. Isto demonstra a importância de se otimizar a concentração dos adjuvantes numa formulação de comprimidos, pois, embora uma pequena variação nesta concentração não exerça efeito significativo no tempo de desintegração, a quantidade de fármaco liberado pode ser substancialmente alterada.

Testes cinemáticos em cosmologia com decaimento do vácuo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Espectro das ondas de spin lineares e não-lineares em multicamadas magnéticas anisotrópicas

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Ondas de spin em nanofilmes nagnéticos acoplados quasiperiodicamente

We studied the spin waves modes that can propagate in magnetic multilayers composed of ferromagnetic metallic films in the nanometer scale. The ferromagnetic films (iron) are separated and coupled through the nonmagnetic spacer films (chromium). The films that make up the multilayer are stacked in a quasiperiodic pattern, following the Fibonacci and double period sequences. We used a phenomenological theory taking into account: the Zeeman energy (between the ferromagnetic films and the external magnetic field), the energy of the magneto-crystalline anisotropy (present in the ferromagnetic films), the energy of the bilinear and biquadratic couplings (between the ferromagnetic films) and the energy of the dipole-dipole interaction (between the ferromagnetic films), to describe the system. The total magnetic energy of the system is numerically minimized and the equilibrium angles of the magnetization of each ferromagnetic film are determined. We solved the equation of motion of the multilayer to find the dispersion relation for the system and, as a consequence, the spin waves modes frequencies. Our theoretical results show that, in the case of trilayers (Fe/Cr/Fe), our model reproduces with excellent agreement experimental results of Brillouin light scattering, known from the literature, by adjusting the physical parameters of the nanofilms. Furthermore, we generalize the model to N ferromagnetic layers which allowed us to determine how complex these systems become when we increase the number of components. It is worth noting that our theoretical calculations generalize all the results known from the literature

Um estudo da abundância de lítio, rotação, atividade cromosférica e magnetismo das estrelas análogas e gêmeas solares

The study physical process that control the stellar evolution is strength influenced by several stellar parameters, like as rotational velocity, convective envelope mass deepening, and magnetic field intensity. In this study we analyzed the interconnection of some stellar parameters, as Lithium abundance A(Li), chromospheric activity and magnetic field intensity as well as the variation of these parameters as a function of age, rotational velocity, and the convective envelope mass deepening for a selected sample of solar analogs and twins stars. In particular, we analyzed the convective envelope mass deepening and the dispersion of lithium abundance for these stars. We also studied the evolution of rotation in subgiants stars, because its belong to the following evolutionary stage of solar analogs, and twins stars. For this analyze, we compute evolutionary models with the TGEC code to derive the evolutionary stage, as well as the convective envelope mass deepening, and derive more precisely the stellar mass, and age for this 118 stars. Our Investigation shows a considerable dispersion of lithium abundance for the solar analogs stars. We also realize that this dispersion is not by the convective zone deep, in this way we observed which the scattering of A(Li) can not be explained by classical theories of mixing in the convective zone. In conclusion we have that are necessary extra-mixing process to explain this decrease of Lithium abundance in solar analogs and twins stars. We analyzed the subgiant stars because this are the subsequent evolutionary stage after the solar analogs and twins stars. For this analysis, we compute the rotational period for 30 subgiants stars observed by Co- RoT satellite. For this task we apply two different methods: Lomb-Scargle algorithm, and the Plavchan Periodogram. We apply the TGEC code we compute models with internal distribution of angular momentum to confront the predict results with the models, and the observational results. With this analyze, we showed which solid body rotation models are incompatible with the physical interpretation of observational results. As a result of our study we still concluded that the magnetic field, convective envelope mass deepening, and internal redistribution of angular momentum are essential to explain the evolution of low-mass stars, and its observational characteristics. Based on population synthesis simulation, we concluded that the solar neighborhood presents a considerable quantity of solar twins when compared with the discovered set nowadays. Altogether we foresee the existence around 400 solar analogs in the solar neighborhood (distance of 100 pc). We also study the angular momentum of solar analogs and twins, in this study we concluded that added angular momentum from a Jupiter type planet, putted in the Jupiter position, is not enough to explain the angular momentum predicted by Kraft law (Kraft 1970)

Inter-relation between soybean yield and soil compaction under degraded pasture in Brazilian Savannah

As pastagens cultivadas do Cerrado brasileiro são responsáveis pela metade da produtividade da carne bovina destinada à alimentação da população, enquanto as culturas agrícolas o são pela terça parte de sua produtividade de grãos, desempenhando importante papel econômico-financeiro para o país. Dessa forma, no ano agrícola 2005/2006, na Fazenda de Ensino e Pesquisa da Faculdade de Engenharia de Ilha Solteira - FEIS/UNESP, foram estudadas a variabilidade e a dependência espacial entre atributos físicos do solo e a produtividade da soja, quando rotacionados após a pastagem degradada com Brachiaria, sobre um Latossolo Vermelho distroférrico. Também foram estudadas correlações lineares e espaciais entre esses atributos, apurando condições que proporcionassem aumento da produtividade agrícola. Para isso, na área com a referida pastagem instalou-se uma malha contendo 124 pontos amostrais, com espaçamentos de 10,0 x 10,0 e de 5,0 x 5,0 m entre eles, numa área total de 7.500 m². Dos pontos de vista linear e espacial, a elevada produtividade de grãos de soja pode ser explicada em razão do número de grãos por planta e da macroporosidade do solo. A alta variabilidade obtida na maioria dos atributos do solo denotou que a integração lavoura-pecuária é um sistema que proporciona heterogeneidade do ambiente físico do solo.