Soil, water and nutrient losses by interrill erosion from green cane cultivation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Perdas de solo, matéria orgânica e nutrientes por erosão hídrica em uma vertente coberta com diferentes quantidades de palha de cana-de-açúcar em Guariba - SP

A erosão em entressulcos resulta da desagregação causada pelo impacto das gotas de chuva na superfície do solo e pelo transporte superficial das partículas do solo desagregadas, onde se encontram a matéria orgânica e os nutrientes fundamentais para a produção agrícola. O presente trabalho teve como objetivo avaliar as perdas de solo, matéria orgânica e nutrientes em uma vertente localizada em uma área de Latossolo Vermelho-Amarelo distrófico, cultivada com cana-de-açúcar, que é colhida mecanicamente. As parcelas experimentais foram submetidas à ação de uma chuva simulada com intensidade de 60 mm h-1, durante 65 minutos. Foram feitas análises do sedimento erodido para a determinação do volume de solução, das perdas de solo, matéria orgânica e nutrientes. Houve maiores perdas de solo, matéria orgânica e nutrientes nos sedimentos oriundos das parcelas com 0% e 25% de cobertura por palha de cana-de-açúcar. em média, essas perdas foram reduzidas nas parcelas com 75% e 100% de cobertura com palha de cana-de-açúcar. Os resultados permitiram concluir que uma cobertura com palha de cana-de-açúcar acima de 50%, da área colhida, reduz a perda de solo e de matéria orgânica, bem como diminui a concentração de nutrientes no sedimento erodido.

Comportamento de atributos físicos de um Latossolo Amarelo sob agroecossistemas do Amazonas

O desmatamento da floresta tropical da Amazônia e a utilização do solo para fins agrícolas potencializam sua degradação física, química e biológica, quando realizados de forma inadequada. Este estudo teve o objetivo de avaliar o efeito de sistemas de uso e manejo de um Latossolo Amarelo, muito argiloso, mediante avaliações de atributos físicos determinados nas profundidades de 0,0-0,2 e 0,2-0,4 m, em área da Universidade do Amazonas, Manaus (AM). Os sistemas de uso e manejo foram: milho, laranja, pupunha, guaraná, pastagem, capoeira e floresta. Nos sistemas com milho, laranja, pupunha e pastagem, foram realizados o desmatamento, a queima e as operações de preparo e cultivo mecanizados. Foram avaliados a composição granulométrica, o grau de floculação da argila, o teor de matéria orgânica, a densidade de partículas, a densidade do solo, a porosidade total, a macro e microporosidade, e a infiltrações inicial e básica. Utilizou-se o delineamento experimental inteiramente casualizado, com três repetições. Os agroecossistemas, em ordem crescente: capoeira, guaraná, milho, laranja, pupunha e pastagem induziram uma degradação dos atributos físicos do solo cultivado em relação ao de floresta, quantificada pelos maiores valores de densidade do solo e menores de macroporosidade, infiltração de água e matéria orgânica.

Análise multivariada e variabilidade espacial na estimativa da erodibilidade de um argissolo vermelho-amarelo

A erodibilidade é um fator de extrema importância na caracterização da perda de solo, representando os processos que regulam a infiltração de água e sua resistência à desagregação e o transporte de partículas. Assim, por meio da análise de dependência espacial dos componentes principais da erodibilidade (fator K), objetivou-se estimar a erodibilidade do solo em uma área de nascentes da microbacia do Córrego do Tijuco, Monte Alto-SP, e analisar a variabilidade espacial das variáveis granulométricas do solo ao longo do relevo. A erodibilidade média da área foi considerada alta, e a análise de agrupamento k-means apontou para uma formação de cinco grupos: no primeiro, os altos teores de areia grossa (AG) e média (AM) condicionaram sua distribuição nas áreas planas; o segundo, caracterizado pelo alto teor de areia fina (AF), distribui-se nos declives mais convexos; o terceiro, com altos teores de silte e areia muito fina (AMF), concentrou-se nos maiores declives e concavidades; o quarto, com maior teor de argila, seguiu as zonas de escoamento de água; e o quinto, com alto teor de matéria orgânica (MO) e areia grossa (AG), distribui-se nas proximidades da zona urbana. A análise de componentes principais (ACP) mostrou quatro componentes com 87,4 % das informações, sendo o primeiro componente principal (CP1) discriminado pelo transporte seletivo de partículas principalmente em zonas pontuais de maior declividade e acúmulo de sedimentos; o segundo (CP2), discriminado pela baixa coesão entre as partículas, mostra acúmulo da areia fina nas áreas de menor cota em toda a área de concentração de água; o terceiro (CP3), discriminado pela maior agregação do solo, concentra-se principalmente nas bases de grandes declives; e o quarto (CP4), discriminado pela areia muito fina, distribui-se ao longo das declividades nas maiores altitudes. Os resultados sugerem o comportamento granulométrico do solo, que se mostra suscetível ao processo erosivo devido às condições texturais superficiais e à movimentação do relevo.

Análise espacial de atributos físicos e carbono orgânico em argissolo vermelho-amarelo cultivado com cana-de-açúcar

A agricultura convencional utiliza o solo intensivamente, modificando os seus atributos. Neste estudo, objetivou-se avaliar a variabilidade espacial de alguns atributos físicos e carbono orgânico do solo em um Argissolo Vermelho-Amarelo cultivado com cana-de-açúcar, usando geoestatística. O trabalho foi realizado em Maracanaú - CE, em uma área de produção de cana-de-açúcar, manejado mediante preparo conservacionista sobre uma cobertura de palhada de cana-de-açúcar. As amostras de solo foram retiradas de uma profundidade de 0,00 - 0,20 m, em uma malha, com intervalo regular de 10 m, totalizando 100 pontos. em cada amostra, foi analisado densidade de partículas, densidade do solo, carbono orgânico, porosidade total, macroposidade e microposidade. O coeficiente de variação indicou variabilidade baixa para densidade de partículas, densidade do solo e porosidade total e média para as variáveis macroporosidade, microporosidade e carbono orgânico. As variáveis analisadas mostraram dependência espacial, a qual foi observada nos mapas de krigagem. A distribuição de poros por tamanho e a porosidade total indicam condições físicas razoavelmente boas, embora com valores de densidade do solo ligeiramente acima do nível considerado adequado para a classe textural do solo.

Caracterização física e química de áreas mineradas pela extração de cassiterita

O objetivo deste trabalho foi caracterizar as diferenças ocorridas, após a atividade da mineração de cassiterita, em uma área de floresta amazônica. As amostras foram coletadas, superficialmente, em área de mineração de cassiterita na Floresta Nacional do Jamari (RO), ao longo de uma linha compreendendo: floresta, capoeira, piso de lavra, área de deposição de rejeito seco e área de deposição de rejeito úmido. em cada situação descrita foram coletadas cinco amostras, que serviram como repetição, totalizando 25. Nas amostras coletadas foram realizadas análises físicas e químicas. O processo de extração de cassiterita promoveu alterações significativas nos atributos dos solos estudados. A matéria orgânica, o fósforo disponível, a densidade de partículas e a resistência à penetração foram os mais alterados pelo processo de supressão da vegetação original e extração do minério.

Taxa de passagem e parâmetros ruminais em bovinos suplementados com enzimas fibrolíticas

Avaliou-se o efeito da adição de enzimas fibrolíticas (celulase e xilanase) sobre as taxas de passagem de partículas e de diluição e os parâmetros ruminais (pH e nitrogênio amoniacal) em animais consumindo dietas contendo silagem de milho e feno de tifton 85 (Cynodon spp.) como volumoso. Oito bovinos com fístulas no rúmen e no duodeno foram distribuídos em dois quadrados latinos 4 x 4, com os tratamentos distribuídos em esquema fatorial 2 x 2 (duas fontes de volumoso e adição ou não de enzimas). O complexo enzimático foi proveniente de fonte comercial e extraído dos fungos Aspergillus niger e Trichoderma longibrachiatum, sendo fornecido na proporção de 12 g/animal/dia, misturado à ração total. Para as taxas de passagem, foram utilizados como marcadores das fases sólida e líquida o cromo-mordente e o cobalto-EDTA, respectivamente. Não houve efeito das enzimas sobre o pH e as concentrações de N-NH3, que apresentaram médias de 6,5 e 22,10 mg/100 mL, respectivamente. A taxa de passagem de partículas no rúmen não foi influenciada pela suplementação enzimática, com médias de 3,4 e 3,0%/h para as dietas contendo silagem de milho e feno de tifton, respectivamente. A taxa de diluição aumentou de 10,07 para 11,84%/h com a adição de enzimas. A suplementação com enzimas fibrolíticas em dietas formuladas com silagem de milho e feno de tifton como volumoso praticamente não alterou os parâmetros avaliados.

Análise e otimização de superfícies seletivas de Frequência utilizando redes neurais artificiais e algoritmos de otimização natural

The bidimensional periodic structures called frequency selective surfaces have been well investigated because of their filtering properties. Similar to the filters that work at the traditional radiofrequency band, such structures can behave as band-stop or pass-band filters, depending on the elements of the array (patch or aperture, respectively) and can be used for a variety of applications, such as: radomes, dichroic reflectors, waveguide filters, artificial magnetic conductors, microwave absorbers etc. To provide high-performance filtering properties at microwave bands, electromagnetic engineers have investigated various types of periodic structures: reconfigurable frequency selective screens, multilayered selective filters, as well as periodic arrays printed on anisotropic dielectric substrates and composed by fractal elements. In general, there is no closed form solution directly from a given desired frequency response to a corresponding device; thus, the analysis of its scattering characteristics requires the application of rigorous full-wave techniques. Besides that, due to the computational complexity of using a full-wave simulator to evaluate the frequency selective surface scattering variables, many electromagnetic engineers still use trial-and-error process until to achieve a given design criterion. As this procedure is very laborious and human dependent, optimization techniques are required to design practical periodic structures with desired filter specifications. Some authors have been employed neural networks and natural optimization algorithms, such as the genetic algorithms and the particle swarm optimization for the frequency selective surface design and optimization. This work has as objective the accomplishment of a rigorous study about the electromagnetic behavior of the periodic structures, enabling the design of efficient devices applied to microwave band. For this, artificial neural networks are used together with natural optimization techniques, allowing the accurate and efficient investigation of various types of frequency selective surfaces, in a simple and fast manner, becoming a powerful tool for the design and optimization of such structures

Análise e síntese de antenas e superfícies seletivas de frequência utilizando computação evolucionária e inteligência de enxames

The frequency selective surfaces, or FSS (Frequency Selective Surfaces), are structures consisting of periodic arrays of conductive elements, called patches, which are usually very thin and they are printed on dielectric layers, or by openings perforated on very thin metallic surfaces, for applications in bands of microwave and millimeter waves. These structures are often used in aircraft, missiles, satellites, radomes, antennae reflector, high gain antennas and microwave ovens, for example. The use of these structures has as main objective filter frequency bands that can be broadcast or rejection, depending on the specificity of the required application. In turn, the modern communication systems such as GSM (Global System for Mobile Communications), RFID (Radio Frequency Identification), Bluetooth, Wi-Fi and WiMAX, whose services are highly demanded by society, have required the development of antennas having, as its main features, and low cost profile, and reduced dimensions and weight. In this context, the microstrip antenna is presented as an excellent choice for communications systems today, because (in addition to meeting the requirements mentioned intrinsically) planar structures are easy to manufacture and integration with other components in microwave circuits. Consequently, the analysis and synthesis of these devices mainly, due to the high possibility of shapes, size and frequency of its elements has been carried out by full-wave models, such as the finite element method, the method of moments and finite difference time domain. However, these methods require an accurate despite great computational effort. In this context, computational intelligence (CI) has been used successfully in the design and optimization of microwave planar structures, as an auxiliary tool and very appropriate, given the complexity of the geometry of the antennas and the FSS considered. The computational intelligence is inspired by natural phenomena such as learning, perception and decision, using techniques such as artificial neural networks, fuzzy logic, fractal geometry and evolutionary computation. This work makes a study of application of computational intelligence using meta-heuristics such as genetic algorithms and swarm intelligence optimization of antennas and frequency selective surfaces. Genetic algorithms are computational search methods based on the theory of natural selection proposed by Darwin and genetics used to solve complex problems, eg, problems where the search space grows with the size of the problem. The particle swarm optimization characteristics including the use of intelligence collectively being applied to optimization problems in many areas of research. The main objective of this work is the use of computational intelligence, the analysis and synthesis of antennas and FSS. We considered the structures of a microstrip planar monopole, ring type, and a cross-dipole FSS. We developed algorithms and optimization results obtained for optimized geometries of antennas and FSS considered. To validate results were designed, constructed and measured several prototypes. The measured results showed excellent agreement with the simulated. Moreover, the results obtained in this study were compared to those simulated using a commercial software has been also observed an excellent agreement. Specifically, the efficiency of techniques used were CI evidenced by simulated and measured, aiming at optimizing the bandwidth of an antenna for wideband operation or UWB (Ultra Wideband), using a genetic algorithm and optimizing the bandwidth, by specifying the length of the air gap between two frequency selective surfaces, using an optimization algorithm particle swarm

Otimização de superfícies seletivas de frequência com elementos pré-fractais utilizando rede neural MLP e algoritmos de busca populacional

This thesis describes design methodologies for frequency selective surfaces (FSSs) composed of periodic arrays of pre-fractals metallic patches on single-layer dielectrics (FR4, RT/duroid). Shapes presented by Sierpinski island and T fractal geometries are exploited to the simple design of efficient band-stop spatial filters with applications in the range of microwaves. Initial results are discussed in terms of the electromagnetic effect resulting from the variation of parameters such as, fractal iteration number (or fractal level), fractal iteration factor, and periodicity of FSS, depending on the used pre-fractal element (Sierpinski island or T fractal). The transmission properties of these proposed periodic arrays are investigated through simulations performed by Ansoft DesignerTM and Ansoft HFSSTM commercial softwares that run full-wave methods. To validate the employed methodology, FSS prototypes are selected for fabrication and measurement. The obtained results point to interesting features for FSS spatial filters: compactness, with high values of frequency compression factor; as well as stable frequency responses at oblique incidence of plane waves. This thesis also approaches, as it main focus, the application of an alternative electromagnetic (EM) optimization technique for analysis and synthesis of FSSs with fractal motifs. In application examples of this technique, Vicsek and Sierpinski pre-fractal elements are used in the optimal design of FSS structures. Based on computational intelligence tools, the proposed technique overcomes the high computational cost associated to the full-wave parametric analyzes. To this end, fast and accurate multilayer perceptron (MLP) neural network models are developed using different parameters as design input variables. These neural network models aim to calculate the cost function in the iterations of population-based search algorithms. Continuous genetic algorithm (GA), particle swarm optimization (PSO), and bees algorithm (BA) are used for FSSs optimization with specific resonant frequency and bandwidth. The performance of these algorithms is compared in terms of computational cost and numerical convergence. Consistent results can be verified by the excellent agreement obtained between simulations and measurements related to FSS prototypes built with a given fractal iteration

Técnicas de computação natural para segmentação de imagens médicas

Image segmentation is one of the image processing problems that deserves special attention from the scientific community. This work studies unsupervised methods to clustering and pattern recognition applicable to medical image segmentation. Natural Computing based methods have shown very attractive in such tasks and are studied here as a way to verify it's applicability in medical image segmentation. This work treats to implement the following methods: GKA (Genetic K-means Algorithm), GFCMA (Genetic FCM Algorithm), PSOKA (PSO and K-means based Clustering Algorithm) and PSOFCM (PSO and FCM based Clustering Algorithm). Besides, as a way to evaluate the results given by the algorithms, clustering validity indexes are used as quantitative measure. Visual and qualitative evaluations are realized also, mainly using data given by the BrainWeb brain simulator as ground truth

Odometria visual baseada em técnicas de structure from motion

Visual Odometry is the process that estimates camera position and orientation based solely on images and in features (projections of visual landmarks present in the scene) extraced from them. With the increasing advance of Computer Vision algorithms and computer processing power, the subarea known as Structure from Motion (SFM) started to supply mathematical tools composing localization systems for robotics and Augmented Reality applications, in contrast with its initial purpose of being used in inherently offline solutions aiming 3D reconstruction and image based modelling. In that way, this work proposes a pipeline to obtain relative position featuring a previously calibrated camera as positional sensor and based entirely on models and algorithms from SFM. Techniques usually applied in camera localization systems such as Kalman filters and particle filters are not used, making unnecessary additional information like probabilistic models for camera state transition. Experiments assessing both 3D reconstruction quality and camera position estimated by the system were performed, in which image sequences captured in reallistic scenarios were processed and compared to localization data gathered from a mobile robotic platform

Análise do efeito do tempo da moagem de alta energia no tamanho de cristalito e microdeformação da rede cristalina do WC-Co

Hard metals are the composite developed in 1923 by Karl Schröter, with wide application because high hardness, wear resistance and toughness. It is compound by a brittle phase WC and a ductile phase Co. Mechanical properties of hardmetals are strongly dependent on the microstructure of the WC Co, and additionally affected by the microstructure of WC powders before sintering. An important feature is that the toughness and the hardness increase simultaneously with the refining of WC. Therefore, development of nanostructured WC Co hardmetal has been extensively studied. There are many methods to manufacture WC-Co hard metals, including spraying conversion process, co-precipitation, displacement reaction process, mechanochemical synthesis and high energy ball milling. High energy ball milling is a simple and efficient way of manufacturing the fine powder with nanostructure. In this process, the continuous impacts on the powders promote pronounced changes and the brittle phase is refined until nanometric scale, bring into ductile matrix, and this ductile phase is deformed, re-welded and hardened. The goal of this work was investigate the effects of highenergy milling time in the micro structural changes in the WC-Co particulate composite, particularly in the refinement of the crystallite size and lattice strain. The starting powders were WC (average particle size D50 0.87 μm) supplied by Wolfram, Berglau-u. Hutten - GMBH and Co (average particle size D50 0.93 μm) supplied by H.C.Starck. Mixing 90% WC and 10% Co in planetary ball milling at 2, 10, 20, 50, 70, 100 and 150 hours, BPR 15:1, 400 rpm. The starting powders and the milled particulate composite samples were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to identify phases and morphology. The crystallite size and lattice strain were measured by Rietveld s method. This procedure allowed obtaining more precise information about the influence of each one in the microstructure. The results show that high energy milling is efficient manufacturing process of WC-Co composite, and the milling time have great influence in the microstructure of the final particles, crushing and dispersing the finely WC nanometric order in the Co particles

Estudo da formulação de massas cerâmicas provenientes da região do Seridó-RN para fabricação de telhas

This work has for objective study compared the characteristics and technological properties of ceramic bodies from the region of Seridó-RN. The region under study has identified 23 cities where they were 80 ceramics industries. To define the universe of search, there was a survey of pottery that are part of APL Seridó next to the IEL. The characteristics and operating conditions of ceramics industries of the region were identified through a socio-economic questionnaire applied locally, which addressed issues such as: profiles of companies, production process etc. The analysis of information collected from 24 companies identified in seven cities shows that the vast majority of industries is small, with family structure, obsolete equipment and labo, little qualified. Most of the pottery works with low technical knowledge, poor control of the production process and product technology. The raw collected were submitted to analysis of X ray diffraction, chemical composition, termical analysis, particle size distribution and plasticity. Then were produced five formulations and made by uniaxial pressure at 25 MPa for firing in temperatures varying from 850 to 1050 °C. The firing technological properties evaluated were: mass loss to fire, lineal shrinkage, apparent density, apparent porosity, water absorption and flexural strength (3 points). The results indicated that the raw materials from the region have significant similarities in the composition chemical and mineralogical. Furthermore, it indicates the possibility of the use of cycles of firing faster and efficient than the current, limited to some clay mass burning of certain conditions

Obtenção de compósitos cerâmicos baseados em Al2O3/TiC através dos precursores poliméricos

The obtaining of ceramic materials from polymeric precursors is subject of numerous studies due to lower energy costs compared to conventional processing. The aim of this study is to investigate and improve the mechanism for obtaining ceramic matrix composite (CMC) based on SiOC/Al2O3/TiC by pyrolysis of polysiloxane in the presence of an active filler and inert filler in the pyrolysis temperature lower than the usually adopted for this technique, with greater strength. It also investigates the influence of pyrolysis temperature, the content of Alas active filler, the presence of infiltrating agents (Al, glass and polymer) after pyrolysis, temperature and infiltration time on some physical and mechanical properties. Alumina is used as inert filler and Al and Ti as active filler in the pyrolysis. Aluminum, glass and polysiloxane are used as agents infiltrating the post-pyrolysis. The results are analyzed with respect to porosity and bulk density by the Archimedes method, the presence of crystalline phases by X-ray diffraction (XRD) and microstructure by scanning electron microscopy (SEM). The ceramic pyrolyzed between 850 °C 1400 °C contain porosity 15% to 33%, density 2.34 g/cm3 and flexural strength at 4 points from 30 to 42 MPa. The microstructure features are porous, with an array of Al2O3 reinforced by TiC particles and AlTi3. The infiltration post-pyrolysis reveals decrease in porosity and increase density and strength. The composites have potential applications where thermal stability is the main requirement