462 research outputs found

    Control Strategies for Hybrid Vehicles in Mountainous Areas

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    AbstractThis paper presents control strategies for a Hybrid Electric Vehicle (HEV) aiming at fuel and battery consumption reduction in real life conditions. For years, car manufacturers have modeled and simulated control strategies using standardized driving cycles based on theoretical speed values such as the NEDC in Europe, leaving important external parameters out of the equation. Establishing driving cycles made out of GPS acquisitions and segmenting them into road sections, classified in different categories depending on the input parameters, including slope, allows the creation of logic rules defining the driving mode to adopt in each situation. Using Fuzzy Logic, those rules can be interpreted and used to adapt the control strategy to road conditions, resulting in many strategies covering every kind of road segment and offering different opportunities of energy savings

    Robust and Biocompatible Functionalization of ZnS Nanoparticles by Catechol-Bearing Poly(2-Methyl-2-Oxazoline)s.

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    Zinc sulfide (ZnS) nanoparticles (NPs) are particularly interesting materials for their electronic and luminescent properties. Unfortunately, their robust and stable functionalization and stabilization, especially in aqueous media, has represented a challenging and not yet completely accomplished task. In this work, we report the synthesis of colloidally stable, photoluminescent and biocompatible core\u2013polymer shell ZnS and ZnS:Tb NPs by employing a water-in-oil miniemulsion (ME) process combined with surface functionalization via catechol-bearing poly-2-methyl-2-oxazoline (PMOXA) of various molar masses. The strong binding of catechol anchors to the metal cations of the ZnS surface, coupled with the high stability of PMOXA against chemical degradation, enable the formation of suspensions presenting excellent colloidal stability. This feature, combined with the assessed photoluminescence and biocompatibility, make these hybrid NPs suitable for optical bioimaging

    Functional bioglass/carbon nanocomposite scaffolds from vat photopolymerization of a novel preceramic polymer-based nanoemulsion

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    Silicone polymers are already known as feedstock for a variety of silicate bioceramics, in the form of scaffolds with complex shapes, obtained by Vat Photopolymerization. Printing is enabled by using silicone blended with photocurable acrylates. The development of a particular silicate composition that functions as a glass or glass-ceramic precursor is possible by the addition of suitable oxide fillers (especially carbonate powders), suspended in the polymer blend. Oxides, from the fillers, easily react with silica left by the thermal transformation of the silicone. The fillers, however, also determine complications in Vat Photopolymerization, due to light scattering; in addition, local oxide concentrations generally impede the obtainment of glassy products. The present paper illustrates a simple solution to these issues, based on the inclusion of a Ca salt in nano-emulsion within a silicone-containing blend. Homogeneous printed samples are later converted into crack-free, fully amorphous ceramic composites, by firing at only 700 °C. The glass matrix, resembling 70S30C (70 % SiO2 and 30 % CaO) bioglass, is achieved according to the quasi-molecular CaO distribution. The secondary phase, promoted by treatment in N2 atmosphere and consisting of pyrolytic carbon, provides a marked photothermal effect

    Logarithmic diffusion and porous media equations: a unified description

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    In this work we present the logarithmic diffusion equation as a limit case when the index that characterizes a nonlinear Fokker-Planck equation, in its diffusive term, goes to zero. A linear drift and a source term are considered in this equation. Its solution has a lorentzian form, consequently this equation characterizes a super diffusion like a L\'evy kind. In addition is obtained an equation that unifies the porous media and the logarithmic diffusion equations, including a generalized diffusion equation in fractal dimension. This unification is performed in the nonextensive thermostatistics context and increases the possibilities about the description of anomalous diffusive processes.Comment: 5 pages. To appear in Phys. Rev.

    Multiple logistic regressions: controlling factors in applications to soil class prediction.

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    Métodos mais eficazes para determinação do padrão de distribuição de classes de solo na paisagem precisam ser avaliados visando suprir a demanda por mapas de solo em escalas regional e global. Neste estudo, Regressões Logísticas Múltiplas foram utilizadas como modelos preditores em uma aplicação de Mapeamento Digital de Solos. Os modelos foram gerados utilizando um mapa de solos existente como variável dependente e atributos de terreno como variáveis independentes, o que possibilitou determinar a probabilidade de encontrar classes de solo na paisagem no primeiro e no segundo nível categórico do SiBCS. A qualidade dos mapas preditos foi verificada por meio da matriz de contingência. A classe dos Argissolos foi predita corretamente, em relação ao mapa original, em aproximadamente 85 %. As classes de solos hidromórficos (Planossolos e Gleissolos) foram preditas corretamente em 75 %. Houve confundimento dos modelos para as classes que ocupam posições muito semelhantes na paisagem. Foi verificado também que classes de solo pouco representativas na paisagem não são adequadamente espacializadas em razão da sensibilidade dos modelos logísticos à proporção relativa das amostras usadas para treinar os modelos

    Change in physical activity after diagnosis of diabetes or hypertension: results from an observational population-based cohort study

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    Background: Chronic diseases like diabetes mellitus or hypertension are a major public health challenge. Irregular physical activity (PA) is one of the most important modifiable risk factors for chronic conditions and their complications. However, engaging in regular PA is a challenge for many individuals. The literature suggests that a diagnosis of a disease might serve as a promising point in time to change health behavior. This study investigates whether a diagnosis of diabetes or hypertension is associated with changes in PA. Methods: Analyses are based on 4261 participants of the population-based KORA S4 study (1999-2001) and its subsequent 7-and 14-year follow-ups. Information on PA and incident diagnoses of diabetes or hypertension was assessed via standardized interviews. Change in PA was regressed upon diagnosis with diabetes or hypertension, using logistic regression models. Models were stratified into active and inactive individuals at baseline to avoid ceiling and floor effects or regression to the mean. Results: Active participants at baseline showed higher odds (OR = 2.16 [1.20;3.89]) for becoming inactive after a diabetes diagnosis than those without a diabetes diagnosis. No other significant association was observed. Discussion: As PA is important for the management of diabetes or hypertension, ways to increase or maintain PA levels in newly-diagnosed patients are important. Communication strategies might be crucial, and practitioners and health insurance companies could play a key role in raising awareness

    Theory of the optical conductivity of (TMTSF)2_2PF6_6 in the mid-infrared range

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    We propose an explanation of the mid-infrared peak observed in the optical conductivity of the Bechgaard salt (TMTSF)2_2PF6_6 in terms of electronic excitations. It is based on a numerical calculation of the conductivity of the quarter-filled, dimerized Hubbard model. The main result is that, even for intermediate values of U/tU/t for which the charge gap is known to be very small, the first peak, and at the same time the main structure, of the optical conductivity is at an energy of the order of the dimerization gap, like in the infinite UU case. This surprising effect is a consequence of the optical selection rules.Comment: 10 pages, 9 uuencoded figure

    Proposta de um modelo de maturidade para Gestão do Conhecimento: KM3

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    A implementação da Gestão do Conhecimento (GC) ocorre em estágios, ou seja, é um processo que demanda mudanças na organização. O objetivo principal desta pesquisa é desenvolver um modelo de maturidade de gestão do conhecimento. Esta pesquisa adotou os princípios da Teoria do Ciclo de Vida. A pesquisa é qualitativa de caráter exploratório. Inicialmente, a partir da análise dos modelos de GC existentes foi desenvolvida uma proposta de Modelo de Maturidade para Gestão do Conhecimento, denominado KM3. Na sequência, esta proposta foi analisada por profissionais. Estes confirmaram os estágios do modelo de maturidade de GC e contribuíram para o refinamento dos fatores alocados em cada estágio. O KM3 é formado por cinco estágios: Falta de Consciência (2 fatores), Planejamento (15 fatores), Iniciação (20 fatores), Desenvolvimento (24 fatores) e Integração (24 fatores)

    Correlation gap in the optical spectra of the two-dimensional organic metal (BEDT-TTF)_4[Ni(dto)_2]

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    Optical reflection measurements within the highly conducting (a,b)-plane of the organic metal (BEDT-TTF)_4[Ni(dto)_2] reveal the gradual development of a sharp feature at around 200 cm as the temperature is reduced below 150 K. Below this frequency a narrow Drude-like response is observed which accounts for the metallic behavior. Since de Haas-von Alphen oscillations at low temperatures confirm band structure calculations of bands crossing the Fermi energy, we assign the observed behavior to a two-dimensional metallic state in the proximity of a correlation induced metal-insulator transition.Comment: 4 pages, 2 figure
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