Dispersão de Orthezia praelonga Douglas, 1891 (Hemiptera: Ortheziidae) causada por equipamentos de pulverização em pomar de citros

A cochonilha O. praelonga é considerada uma importante praga dos citros no Brasil, e informações sobre a sua dispersão estão baseadas apenas em observações empíricas. Objetivou-se avaliar o efeito de equipamentos de pulverização comumente utilizados pelos citricultores na dispersão da praga. Armadilhas adesivas foram instaladas no solo e em vergalhões dispostos verticalmente às plantas de três linhas adjacentes em um talhão de citros contendo plantas infestadas pela praga. Foram adotados equipamentos utilizados para controle de pragas dos citros. A avaliação da dispersão foi realizada por meio da contagem de fêmeas, ninfas ou partes dos insetos aderidas às armadilhas adesivas. Os equipamentos Martignani e Bié foram capazes de lançar a praga a até 15 m, enquanto, para o equipamento Turbo Valência, detectaram-se fragmentos cerosos a até 22 m da máquina. Os equipamentos dotados de pistola não causaram qualquer dispersão da praga. Portanto, evidenciou-se que mesmo a utilização de equipamentos para controle de outras pragas pode favorecer a dispersão da cochonilha O. praelonga em pomares de citros, e isso deve ser considerado no aprimoramento do programa de manejo integrado de pragas dos citros.

Caracterização física do solo e desempenho operacional de máquinas agrícolas na implantação da cultura do sorgo forrageiro

Forage sorghum can be grown in areas presenting dry and hot environmental situations where the yield of other grasses can often be uneconomical. The objective of this study was to analyze the operating performance of agricultural machines in the deployment of sorghum forage in four tillage systems, as follows: no-tillage system, disk harrow + seeding, disk harrow + two light disking + seeding, minimum tillage + seeding and four seeding different speeds, as follows: 3, 5, 6 and 9 km h(-1). The study was performed under field conditions in FCA/UNESP, Botucatu County, SP, Brazil. The data were subjected to variance analysis in a simple factorial 4 x 4, and a random block design with split plots. Operational performance of the agricultural machinery, physical characteristics the soil, its water content and the yield of dry matter and green sorghum were determined. The operational performance of agricultural machines in the deployment of sorghum forage is influenced by the sowing speed and the soil tillage system used. Chisel plow was the equipment that required the highest mean traction force, mean traction and slip, as well as the lowest mean speed for the studied tillage system. Forage sorghum showed higher yields in no-tillage systems at a seeding speed of 5 km h(-1).

Consumo de combustível na operação de subsolagem realizada antes e depois de diferentes sistemas de preparo periódico do solo

A subsolagem tem aumentado nos últimos anos de forma indiscriminada, faltando estudos que norteiem os melhores procedimentos para que novos problemas não sejam acrescentados devido a subsolagens inadequadas ou mesmo em solos onde a operação é desnecessária, e principalmente buscar redução no consumo de combustível. Dessa forma, este trabalho teve o objetivo de avaliar o consumo de combustível na operação de subsolagem efetuada antes e depois de diferentes sistemas de preparo periódico do solo, classificado como Nitossolo Vermelho distroférrico. Os preparos foram realizados com arado de discos, arado de discos mais uma gradagem de nivelamento, grade pesada, grade pesada mais gradagem de nivelamento e escarificador. A realização da subsolagem depois dos sistemas de preparo periódico requereu 15% menos de potência na barra de tração. A subsolagem depois dos diferentes sistemas de preparo economizou 16,5% de combustível por área. O deslizamento das rodas motrizes e a velocidade média operacional obtiveram melhor desempenho quando se realizou a subsolagem depois do preparo do solo.

Semeadura direta de milho com dois tipos de sulcadores de adubo, em nível e no sentido do declive do terreno

O presente estudo teve como objetivo avaliar parâmetros operacionais de um conjunto mecanizado envolvendo trator e semeadora, assim como o rendimento da cultura do milho semeada nas diferentes configurações das máquinas e combinações com o ambiente de produção. Os tratamentos consistiram de tipos de sulcadores (discos duplos e hastes), os quais foram avaliados em experimentos em que a operação de semeadura direta do milho foi efetuada transversalmente ao declive (em nível) e em aclive e declive. A semeadura contra o declive e o uso de haste sulcadora implicaram maior demanda de esforço de tração, patinagem do trator e consumo de combustível por área trabalhada e não influenciaram o volume de solo mobilizado, a população de plantas e a produtividade de grãos do milho, em relação à operação realizada em declive e uso de sulcador de discos duplos, respectivamente. A utilização de sulcador do tipo haste resultou em menor número de plantas acamadas e quebradas, em relação ao uso de discos duplos, independentemente do sentido da operação. A principal diferença entre semear em nível ou em declive é a formação de sulcos orientados no sentido do terreno, pela ação de sulcadores do tipo haste e elevada patinagem dos rodados do trator, já que o consumo de combustível por área trabalhada e capacidade operacional não foram afetados por aquelas variáveis.

Influência da altura das garras dos pneus de um trator em área de plantio direto

This work was carried out to evaluate the performance of a farm tractor fitted with two sets of tires with high lugs and another set of tires with tallow lugs in straw without tillage (corn straw). The travel speeds used were approximately 4, 5, 6 and 7 km h(-1) and a constant pulling force of 25 kN was fixed. Tractor traction, forward speed, slip and consumption of fuel were measured and drawbar power, the ratio between the consumption and power and traction coefficient were calculated. It was observed that the tractor performance was similar to high and low lug tire conditions, in an area covered with corn straw.

Desempenho de trator agrícola em três superfícies de solo e quatro velocidades de deslocamento

The aim of this work was to evaluate tractor performance in soil with three different surfaces: firm soil without covering, mobilized soil, and firm soil with vegetal residue of corn and braquiaria, for four forward speeds. The experiment was accomplished in three plots determined by the soil conditions. In each plot four treatments were composed by the forward speed obtained by the changes of the tractor gear. Six repetitions were used in each plot, totaling 72 experimental units, combination of the traction, slip of the rear and front wheels, forward speed and fuel consumption. The values of the tractor performance obtained led to the conclusion that in the firm soil without vegetable covering the tractor performance was better, followed by the soil with the firm surface and covered with corn straw and braquiaria and finally the mobilized soil. The best tractor performance was obtained in the C1 gear that supplied the forward speed of 6 km h(-1).

Estudo da introdução de resíduo de britagem de rocha calcária e cinza de biomassa de cana-de-açúcar em formulações de argamassas colantes

The adhesive mortars are a mixture of cement, sand, and additives to polymers that retain the mixing water and promotes adherence, being used in setting on various ceramic substrates. The sand used in the production of these mortars is from the riverbeds, and with the increasing restriction of these sands extraction by environmental agencies, and often having to be transported over long distances to the consumer center. This work aims to design and physical and mechanical characterization of ecological adhesive mortar with total replacement of natural sand by sand from the crushing of limestone, and the addition of mineral ash biomass of cane sugar in partial replacement cement used in the production of adhesive mortar , aiming compositions that meet the regulatory specifications for use adhesive mortar. Standardized tests to determine the tensile bond strength (NBR 14081-4), determination of open time (NBR 14081-3) and determination of slip (NBR 14081-5) were performed. Were also conducted trials squeeze flow in different formulation, the mortar with addition of 15 % gray biomass of cane sugar for cement mortars as well as the total replacement of natural sand by sand limestone crushing, got the best performance among the mortars studied, it was found that the addition of biomass to replace cement is perfectly feasible due to its pozzolanic activity, which contributed to this reduction in the cement matrix formation of adhesive mortar

Simulação computacional da interação fluido-estrutura em bombas de cavidades progressivas

The pumping through progressing cavities system has been more and more employed in the petroleum industry. This occurs because of its capacity of elevation of highly viscous oils or fluids with great concentration of sand or other solid particles. A Progressing Cavity Pump (PCP) consists, basically, of a rotor - a metallic device similar to an eccentric screw, and a stator - a steel tube internally covered by a double helix, which may be rigid or deformable/elastomeric. In general, it is submitted to a combination of well pressure with the pressure generated by the pumping process itself. In elastomeric PCPs, this combined effort compresses the stator and generates, or enlarges, the clearance existing between the rotor and the stator, thus reducing the closing effect between their cavities. Such opening of the sealing region produces what is known as fluid slip or slippage, reducing the efficiency of the PCP pumping system. Therefore, this research aims to develop a transient three-dimensional computational model that, based on single-lobe PCP kinematics, is able to simulate the fluid-structure interaction that occurs in the interior of metallic and elastomeric PCPs. The main goal is to evaluate the dynamic characteristics of PCP s efficiency based on detailed and instantaneous information of velocity, pressure and deformation fields in their interior. To reach these goals (development and use of the model), it was also necessary the development of a methodology for generation of dynamic, mobile and deformable, computational meshes representing fluid and structural regions of a PCP. This additional intermediary step has been characterized as the biggest challenge for the elaboration and running of the computational model due to the complex kinematic and critical geometry of this type of pump (different helix angles between rotor and stator as well as large length scale aspect ratios). The processes of dynamic generation of meshes and of simultaneous evaluation of the deformations suffered by the elastomer are fulfilled through subroutines written in Fortan 90 language that dynamically interact with the CFX/ANSYS fluid dynamic software. Since a structural elastic linear model is employed to evaluate elastomer deformations, it is not necessary to use any CAE package for structural analysis. However, an initial proposal for dynamic simulation using hyperelastic models through ANSYS software is also presented in this research. Validation of the results produced with the present methodology (mesh generation, flow simulation in metallic PCPs and simulation of fluid-structure interaction in elastomeric PCPs) is obtained through comparison with experimental results reported by the literature. It is expected that the development and application of such a computational model may provide better details of the dynamics of the flow within metallic and elastomeric PCPs, so that better control systems may be implemented in the artificial elevation area by PCP

Análise tribológica de um sistema de acionamento alternativo de pigs para a indústria do petróleo

It is analyzed through the concepts of tribology and mechanical contact and damage the suggestion of implementing a backup system for traction and passage of Pipeline Inspection Gauge (Pig) from the inside of pipelines. In order to verify the integrity of the pipelines, it is suggested the possibility of displacement of such equipment by pulling wires with steel wires. The physical and mechanical characteristics of this method were verified by accelerated tests in the laboratory in a tribological pair, wire versus a curve 90. It also considered the main mechanisms of wear of a sliding system with and without lubricant, in the absence and presence of contaminants. To try this, It was constructed a test bench able to reproduce a slip system, work on mode back-and-forth ("reciprocation"). It was used two kinds of wires, a galvanized steel and other stainless steel and the results achieved using the two kinds of steel cables were compared. For result comparative means, it was used steel cables with and without coating of Poly Vinyl Chloride (PVC). The wires and the curves of the products were characterized using metallographic analysis, microhardness Vickers tests, X-ray diffraction (XRD), X-Ray Refraction (XRF) and tensile tests. After the experiments were analyzed some parameters that have been measurable, it demonstrates to the impracticality of this proposed method, since the friction force and the concept of alternating request at the contact between the strands of wire and the inner curves that are part ducts caused severe wear. These types of wear are likely to cause possible failures in future products and cause fluid leaks

Avaliação de estratégias de detecção e correção de perdas de ciclos na portadora GPS L1

To prevent large errors in the GPS positioning, cycle slips should be detected and corrected. Such procedure is not trivial, mainly for single frequency receivers, but normally it is not noticed by the users. Thus, it will be discussed some practical and more used methods for cycle slips detection and correction using just GPS single-frequency observations. In the detection, the triple (TD) and tetra differences were used. In relation to the correction, in general, each slip is corrected in the preprocessing. Otherwise, other strategies should be adopted during the processing. In this paper, the option was to the second option, and two strategies were tested. In one of them, the elements of the covariance matrix of the involved ambiguities are modified and new ambiguity estimation starts. In the one, a new ambiguity is introduced as additional unknown when a cycle slip is detected. These possibilities are discussed and compared in this paper, as well as the aspects related to the practicity, implementation and viability of each one. Some experiments were carried out using simulated data with cycle slips in different satellites and epochs of the data. This allowed assessing and comparing the results of different occurrence of cycle slip and correction in several conditions.

Fases magnéticas de sistemas nanoestruturados de terras-raras

There is presently a worldwide interest in artificial magnetic systems which guide research activities in universities and companies. Thin films and multilayers have a central role, revealing new magnetic phases which often lead to breakthroughs and new technology standards, never thought otherwise. Surface and confinement effects cause large impact in the magnetic phases of magnetic materials with bulk spatially periodic patterns. New magnetic phases are expected to form in thin film thicknesses comparable to the length of the intrinsic bulk magnetic unit cell. Helimagnetic materials are prototypes in this respect, since the bulk magnetic phases consist in periodic patterns with the length of the helical pitch. In this thesis we study the magnetic phases of thin rare-earth films, with surfaces oriented along the (002) direction. The thesis includes the investigation of the magnetic phases of thin Dy and Ho films, as well as the thermal hysteresis cycles of Dy thin films. The investigation of the thermal hysteresis cycles of thin Dy films has been done in collaboration with the Laboratory of Magnetic Materials of the University of Texas, at Arlington. The theoretical modeling is based on a self-consistent theory developed by the Group of Magnetism of UFRN. Contributions from the first and second neighbors exchange energy, from the anisotropy energy and the Zeeman energy are calculated in a set of nonequivalent magnetic ions, and the equilibrium magnetic phases, from the Curie temperature up to the Nèel temperature, are determined in a self-consistent manner, resulting in a vanishing torque in the magnetic ions at all planes across the thin film. Our results reproduce the known isothermal and iso-field curves of bulk Dy and Ho, and the known spin-slip phases of Ho, and indicate that: (i) the confinement in thin films leads to a new magnetic phase, with alternate helicity, which leads to the measured thermal hysteresis of Dy ultrathin films, with thicknesses ranging from 4 nm to 16 nm; (ii) thin Dy films have anisotropy dominated surface lock-in phases, with alignment of surface spins along the anisotropy easy axis directions, similar to the known spin-slip phases of Ho ( which form in the bulk and are commensurate to the crystal lattice); and (iii) the confinement in thin films change considerably the spin-slip patterns of Ho.

Modeling of interfaces in two-dimensional problems using solid finite elements with high aspect ratio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A mixture theory based method for three-dimensional modeling of reinforce concrete members with embedded crack finite elements

The paper presents a methodology to model three-dimensional reinforced concrete members by means of embedded discontinuity elements based on the Continuum Strong Discontinuous Approach (CSDA). Mixture theory concepts are used to model reinforced concrete as a 31) composite material constituted of concrete with long fibers (rebars) bundles oriented in different directions embedded in it. The effects of the rebars are modeled by phenomenological constitutive models devised to reproduce the axial non-linear behavior, as well as the bond-slip and dowel action. The paper presents the constitutive models assumed for the components and the compatibility conditions chosen to constitute the composite. Numerical analyses of existing experimental reinforced concrete members are presented, illustrating the applicability of the proposed methodology.

Comportamento plástico do aço inoxidável austenítico em baixa temperatura

Ensaios de tração uniaxiais foram empregados para deformar aços inoxidáveis austeníticos do tipo 304, em diferentes temperaturas abaixo da ambiente (de 77 K a 300 K). A relação entre a estabilidade da austenita e o encruamento, em função da temperatura de teste, é discutida quanto à transformação martensítica induzida por deformação e ao deslizamento de discordâncias na austenita. em curvas tensão-deformação que assumem a equação de Ludwik sigma = sigmao + képsilonn, na qual sigma é a tensão verdadeira e e a elongação plástica verdadeira, um modo conveniente para analisar o encruamento é por meio do diagrama log dsigma / dépsilon versus log épsilon. O aspecto significativo é a variação da taxa de encruamento dsigma / dépsilon com a elongação plástica verdadeira nas diferentes temperaturas. As mudanças no comportamento do encruamento motivando até três estágios de deformação são associadas a diferentes processos microestruturais. A transformação martensítica pode ser considerada como um processo de deformação que compete com o processo usual de deslizamento. A investigação desses estágios, na região plástica, produz uma referência qualitativa de como diferentes fatores, tais como o grau de deformação, temperatura e composição química da austenita, afetam a transformação austenita-martensita.

Stabilizing controller design for uncertain nonlinear systems using fuzzy models

A Lyapunov-based stabilizing control design method for uncertain nonlinear dynamical systems using fuzzy models is proposed. The controller is constructed using a design model of the dynamical process to be controlled. The design model is obtained from the truth model using a fuzzy modeling approach. The truth model represents a detailed description of the process dynamics. The truth model is used in a simulation experiment to evaluate the performance of the controller design. A method for generating local models that constitute the design model is proposed. Sufficient conditions for stability and stabilizability of fuzzy models using fuzzy state-feedback controllers are given. The results obtained are illustrated with a numerical example involving a four-dimensional nonlinear model of a stick balancer.