1,048 research outputs found

    Optimal Robust Nonlinear LQG/LTR Control with Application to Longitudinal Flight Control

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    As part of the development of a new 4D Autopilot System for Unmanned Aerial Aircrafts (UAVs), i.e. a time-dependent robust trajectory generation and control algorithm, this work addresses the problem of optimal path finding based on the aircraft’s own sensors data output, that may be unreliable due to noise on data acquisition and/or transmission under certain circumstances. Although several filtering methods, such as the Kalman-Bucy Filter or the LQG/LTR, are available, the utter complexity of the new control system, together with the robustness and reliability required of such a system on an UAV for airworthiness certifiable autonomous flight, required the development of a proper robust filter for a nonlinear system, as a way of further mitigate errors propagation to the control system and improve its performance. As such, a new nonlinear LQG/LTR algorithm, validated through computational simulation testing, is proposed on this paper. This research work was conducted in the Laboratory of Avionics and Control of the Department of Aerospace Sciences (DCA) at the Faculty of Engineering of the University of Beira Interior and supported by the Aeronautics and Astronautics Research Group (AeroG) of the Associated Laboratory for Energy, Transports and Aeronautics (LAETA).info:eu-repo/semantics/publishedVersio

    Parasympathetic dysfunction is associated with insulin resistance in fructose-fed female rats

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    The objective of the present study was to identify metabolic, cardiovascular and autonomic changes induced by fructose overload administered in the drinking water of rats for 8 weeks. Female Wistar rats (200-220 g) were divided into 2 groups: control (N = 8) and fructose-fed rats (N = 5; 100 mg/L fructose in drinking water for 8 weeks). The autonomic control of heart rate was evaluated by pharmacological blockade using atropine (3 mg/kg) and propranolol (4 mg/kg). The animals were submitted to an intravenous insulin tolerance test (ITT) and to blood glucose measurement. The fructose overload induced a significant increase in body weight (~10%) and in fasting glycemia (~28%). The rate constant of glucose disappearance (KITT) during ITT was lower in fructose-fed rats (3.25 ± 0.7%/min) compared with controls (4.95 ± 0.3%/min, P < 0.05) indicating insulin resistance. The fructose-fed group presented increased arterial pressure compared to controls (122 ± 3 vs 108 ± 1 mmHg, P < 0.05) and a reduction in vagal tonus (31 ± 9 vs 55 ± 5 bpm in controls, P < 0.05). No changes in sympathetic tonus were observed. A positive correlation, tested by the Pearson correlation, was demonstrable between cardiac vagal tonus and KITT (r = 0.8, P = 0.02). These data provided new information regarding the role of parasympathetic dysfunction associated with insulin resistance in the development of early metabolic and cardiovascular alterations induced by a high fructose diet.FAPESPCAPES-PROSU

    Etnocultivo do jambu para abastecimento da cidade de Belém, estado do Pará.

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    O jambu que faz parte da gastronomia cultural dos paraenses como componente do pato-notucupi e tacacá vem sofrendo grandes transformações com relação a sua utilização. É cultivado por produtores periurbanos em pequenas áreas, em conjunto com outras hortaliças, sobretudo para atender o consumo da cidade de Belém e dos principais núcleos urbanos da mesorregião do Nordeste Paraense. Foi efetuado um levantamento histórico da utilização do jambu, das mudanças com relação e seu emprego na culinária, para indústria de cosméticos e fármacos e nas práticas usadas pelos agricultores periurbanos dos municípios de Ananindeua, Benevides, Santa Izabel do Pará e Santo Antônio de Tauá. A urbanização e a especulação de terras nas áreas próximas de Belém, o surgimento de polos de produção em outros estados e países, o processo de patenteamento para novos produtos no exterior e uso na gastronomia nacional e internacional estão transformando o jambu em uma nova hortaliça dos trópicos

    Comercialização e uso de produtos inseticidas para controle da mosca-dos-chifres em Aquidauana, MS.

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    A mosca-dos-chifres é considerada um sério problema econômico à pecuária devido aos prejuízos causados à produção e gastos com controle. Este estudo objetivou conhecer o perfil da comercialização e uso dos produtos inseticidas para controle da mosca-dos-chifres no município de Aquidauana, MS. De nov/1999 a nov/2000, informações foram obtidas em estabelecimentos agropecuários na cidade de Aquidauana e em entrevistas com produtores rurais e gerentes de fazendas. Um total de 29 produtos indicados para o controle da mosca foram encontrados nos estabelecimentos, pertencentes aos grupos dos piretróides (58,6%), organofosforados (3,4%), fenil pirazoles (3,4%), lactonas macrocíclicas (3,4%) e associações entre inseticidas (31,0%). A cipermetrina foi o princípio ativo mais comum, presente em 69,0% dos produtos (incluindo associações). Informações obtidas em 212 propriedades evidenciaram uma ampla utilização de produtos piretróides, empregados rotineiramente em 89,6% das propriedades, a maioria dos quais à base de cipermetrina (69,8%) e deltametrina (48,1%). A utilização de produtos de outras classes inseticidas é mínima. O domínio dos produtos piretróides, em termos de comercialização e uso no município de Aquidauana, explica os crescentes problemas de controle da mosca-dos-chifres e o desenvolvimento de resistência a inseticidas desta classe.bitstream/item/37420/1/BP32.pd

    Modeling self-organization of thin strained metallic overlayers from atomic to micron scales

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    A computational study of the self-organization of heteroepitaxial ultrathin metal films is presented. By means of a continuum complex field model, the relationship of the equilibrium surface patterns of the film to the adsorbate-substrate adhesion energy, as well as to the mismatch between the adsorbate and the substrate bulk lattice parameters, are obtained in both the tensile and the compressive regimes. Our approach captures pattern periodicities over large length scales, up to several hundreds of nm, retaining atomistic resolution. Thus, the results can be directly compared with experimental data, in particular for systems such as Cu/Ru(0001) and Ag/Cu(111). Three nontrivial, stable superstructures for the overlayer, namely, stripe, honeycomb, and triangular, are identified that closely resemble those observed experimentally. Simulations in nonequilibrium conditions are performed as well to identify metastable structural configurations and the dynamics of ordering of the overlayer.Peer reviewe

    Patterning of Heteroepitaxial Overlayers from Nano to Micron Scales

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    Thin heteroepitaxial overlayers have been proposed as templates to generate stable, self-organized nanostructures at large length scales, with a variety of important technological applications. However, modeling strain-driven self-organization is a formidable challenge due to different length scales involved. In this Letter, we present a method for predicting the patterning of ultrathin films on micron length scales with atomic resolution. We make quantitative predictions for the type of superstructures (stripes, honeycomb, triangular) and length scale of pattern formation of two metal-metal systems, Cu on Ru(0001) and Cu on Pd(111). Our findings are in excellent agreement with previous experiments and call for future experimental investigations of such systems.Peer reviewe

    On the dissipative non-minimal braneworld inflation

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    We study the effects of the non-minimal coupling on the dissipative dynamics of the warm inflation in a braneworld setup, where the inflaton field is non-minimally coupled to induced gravity on the warped DGP brane. We study with details the effects of the non-minimal coupling and dissipation on the inflationary dynamics on the normal DGP branch of this scenario in the high-dissipation and high-energy regime. We show that incorporation of the non-minimal coupling in this setup decreases the number of e-folds relative to the minimal case. We also compare our model parameters with recent observational data.Comment: 32 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1001.044
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