7,497 research outputs found

    Emission Profiles of Carbonyl Compounds at a Brazilian Charcoal Plant

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    A indústria siderúrgica brasileira consome grandes quantidades de carvão vegetal. As carvoarias são responsáveis por emissões atmosféricas de compostos orgânicos voláteis tais como compostos carbonílicos (CC). Neste trabalho, foram determinados o perfil e as concentrações de CC em fase vapor durante a produção de carvão vegetal a partir de eucalipto. As amostras foram coletadas próximas aos fornos, em cartuchos de sílica revestidos com 2,4-dinitrofenilidrazina e, em seguida, extraídas e analisadas por HPLC-DAD-MS (cromatografia líquida de alta eficiência acoplada a detector de arranjo de diodo e espectrômetro de massas). Doze CC foram identificados e quantificados, entre eles acetaldeído e os pares coeluídos furfural/propanal, acroleína/propanona e 2-pentenal/pentanal. Estes três pares tiveram seus picos resolvidos por meio de espectrometria de massas para doze amostras e individualmente quantificados. Os perfis obtidos indicaram uma maior abundância do par furfural/propanal nas três fases de carbonização, seguido do acetaldeído na primeira fase e do 2-oxobutanal nas segunda e terceira fases. Furfural/propanal e acetaldeído se destacaram dentre os CC determinados nas proximidades dos fornos, com concentrações médias de 4948 e 2558 µg m -3 e concentrações máximas de 11655 e 4805 µg m -3 , respectivamente. Brazilian steel industry consumes huge amounts of charcoal. The charcoal plants are responsible for atmospheric emissions of volatile organic compounds such as carbonyl compounds (CC). In this work, the profile and the concentrations of CC in the vapor phase were determined during the charcoal production from eucalyptus. Samples were collected near kilns on silica cartridges coated with 2,4-dinitrophenylhydrazine, and then extracted and analyzed by HPLC-DAD-MS (high performance liquid chromatography coupled with diode array detector and mass spectrometry). Twelve CC were identified and quantified, amongst them acetaldehyde and the co-eluting acrolein/ propanone, furfural/propanal and 2-pentenal/pentanal pairs. These three pairs were peak resolved by mass spectra for twelve samples and thus individually quantified. The profiles obtained indicated the furfural/propanal pair as the most abundant in all three carbonization stages, followed by acetaldehyde in the first stage and 2-oxobutanal in the second and third stages. Furfural/propanal and acetaldehyde stood out among CC determined near the kilns, with average concentrations of 4948 and 2558 µg m -3 and maximum concentrations of 11655 and 4805 µg m -3 , respectively

    Optimal Rendezvous Trajectory for Unmanned Aerial-Ground Vehicles

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    (c) 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Fixed-wing unmanned aerial vehicles (UAVs) can be an essential tool for low cost aerial surveillance and mapping applications in remote regions. There is however a key limitation, which is the fact that low cost UAVs have limited fuel capacity and hence require periodic refueling to accomplish a mission. Moreover, the usual mechanism of commanding the UAV to return to a stationary base station for refueling can result in fuel wastage and inefficient mission operation time. Alternatively, one strategy could be the use of an unmanned ground vehicle (UGV) as a mobile refueling unit, where the UAV will rendezvous with the UGV for refueling. In order to accurately perform this task in the presence of wind disturbances, we need to determine an optimal trajectory in 3D taking UAV and UGV dynamics and kinematics into account. In this paper, we propose an optimal control formulation to generate a tunable UAV trajectory for rendezvous on a moving UGV that also addresses the possibility of the presence of wind disturbances. By a suitable choice of the value of an aggressiveness index that we introduce in our problem setting, we are able to control the UAV rendezvous behavior. Several numerical results are presented to illustrate the reliability and effectiveness of our approach

    The long-term evolution of the Douro River as evidenced by strath terrace staircases located at NE Portugal (western Iberia)

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    In western Iberia, mechanisms that explain the transition from endorheic to exorheic continental-scale drainage reorganisation are foreland basin overspill, headwards erosion and capture by an Atlantic river, or a combination of both. To explore these controls we have investigated the Portuguese sector of the Douro River, the site of drainage re-organsation. The Douro River routes downstream through weak sedimentary infill of the Douro Cenozoic Basin (Spain), after which the river cuts down through granitic and metamorphic rocks cut by active fault zones (NE Portugal), before reaching the Atlantic coast. We investigated the drainage reorganisation using an integrated remote sensing, field survey and geochronological approach applied to Pliocene-Quaternary fluvial sediments and landforms. The older drainage record is documented by a series of high and intermediate landform levels comprising 1) a high level (1000-600 m) faulted regional fluvial erosion surface, the North Iberian Meseta Planation Surface (NIMPS); 2) an inset level (650-600 m altitude) comprising a broad fluvial surface formed onto a large ENE-WSW depression that overlies resistant ProterozoicandPaleozoic bedrock and 3) an inset (500450m) fluvial surface. The younger drainage record comprises an entrenched fluvial strath terrace sequence of up to 9 levels (T9 = oldest positioned at 246-242 m above the modern river base (a.r.b); T1 = youngest positioned at 17-13 m a.r.b.). Levels T1 and T3 display fault offsets where the cross active NNE-SSW fault zones. The three lowest terrace levels (T1-T3) were dated using optically stimulated luminescence (OSL) techniques using Quartz-OSL and post infra-red stimulated luminescence (pIRIR). Results ranged from 39-12ka (T1), 57ka (T2) and >360ka (minimum) (T3). Fluvial incision rates of the younger (terrace) drainage record were quantified and temporally exptrapolated to model the ages of the high to intermediate elevation levels of the early drainage record. Integration of incision data with fault zone derived crustal uplift values informs on the timing of the endorheic to exhoreic drainage reorganization. We interpret the NIMPS to be part of the endorehic Douro Cenozoic Basin drainage divide erosion. The inset wide fluvial surface at 650-600 m altitude represents the overspill level in the area of the Mesão Frio ridges (drainage divide with the Atlantic drainage). Development of the exhoreic ancestral Douro valley is documented in the 500-450 m fluvial surface with our age and uplift modelling suggesting this became established during the upper Pleistocene (3.6 Ma) through to the Early Pleistocene (1.8 Ma). The entrenched river terrace sequence spans the Pleistocene, developing via spatial and temporal variations in rock strength, uplift and cyclic cool climate variability as the river adjusts to the Atlantic base level

    Prevalence and predictors of coronary artery disease in patients with a calcium score of zero

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    The absence of coronary calcification is associated with an excellent prognosis. However, a calcium score of zero does not exclude the presence of coronary artery disease (CAD) or the possibility of future cardiovascular events. Our aim was to study the prevalence and predictors of coronary artery disease in patients with a calcium score of zero. Prospective registry consisted of 3,012 consecutive patients that underwent cardiac CT (dual source CT). Stable patients referred for evaluation of possible CAD that had a calcium score of zero (n = 864) were selected for this analysis. The variables that were statistically significant were included in a multivariable logistic regression model. From 864 patients with a calcium score of zero, 107 (12.4 %) had coronary plaques on the contrast CT (10.8 %, n = 93 with nonobstructive CAD and 1.6 %, n = 14 with obstructive CAD). By logistic regression analysis, the independent predictors of CAD in this population were age >55 years [odds ratio (OR) 1.63 (1.05-2.52)], hypertension [OR 1.64 (1.05-2.56)] and dyslipidemia [OR 1.54 (1.00-2.36)]. In the presence of these 3 variables, the probability of having coronary plaques was 21 %. The absence of coronary artery calcification does not exclude the presence of coron

    Mineralization of Sialoliths Investigated by Ex Vivo and In Vivo X-ray Computed Tomography

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    The fraction of organic matter present affects the fragmentation behavior of sialoliths; thus, pretherapeutic information on the degree of mineralization is relevant for a correct selection of lithotripsy procedures. This work proposes a methodology for in vivo characterization of salivary calculi in the pretherapeutic context. Sialoliths were characterized in detail by X-ray computed microtomography (μCT) in combination with atomic emission spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Correlative analysis of the same specimens was performed by in vivo and ex vivo helical computed tomography (HCT) and ex vivo μCT. The mineral matter in the sialoliths consisted essentially of apatite (89 vol%) and whitlockite (11 vol%) with average density of 1.8 g/cm3. In hydrated conditions, the mineral mass prevailed with 53 ± 13 wt%, whereas the organic matter, with a density of 1.2 g/cm3, occupied 65 ± 10% of the sialoliths' volume. A quantitative relation between sialoliths mineral density and X-ray attenuation is proposed for both HCT and μCT.info:eu-repo/semantics/publishedVersio

    Coronary computed tomography angiography-adapted Leaman score as a tool to noninvasively quantify total coronary atherosclerotic burden

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    To describe a coronary computed tomography angiography (CCTA)-adapted Leaman score (CT-LeSc) as a tool to quantify total coronary atherosclerotic burden with information regarding localization, type of plaque and degree of stenosis and to identify clinical predictors of a high coronary atherosclerotic burden as assessed by the CT-LeSc. Single center prospective registry including a total of 772 consecutive patients undergoing CCTA (Dual-source CT) from April 2011 to March 2012. For the purpose of this study, 581 stable patients referred for suspected coronary artery disease (CAD) without previous myocardial infarction or revascularization procedures were included. Pre-test CAD probability was determined using both the Diamond-Forrester extended CAD consortium method (DF-CAD consortium model) and the Morise score. Cardiovascular risk was assessed with the HeartScore. The cut-off for the 3rd tercile (CT-LeSc ≥8.3) was used to define a population with a high coronary atherosclerotic burden. The median CT-LeSc in this population (n = 581, 8,136 coronary segments evaluated; mean age 57.6 ± 11.1; 55.8 % males; 14.6 % with diabetes) was 2.2 (IQR 0-6.8). In patients with CAD (n = 341), the median CT-LeSc was 5.8 (IQR 3.2-9.6). Among patients with nonobstructive CAD, most were classified in the lowest terciles (T1, 43.0 %; T2, 36.1 %), but 20.9 % were in the highest tercile (T3). The majority of the patients with obstructive CAD were classified in T3 (78.2 %), but 21.8 % had a CT-LeSc in lower terciles (T1 or T2). The independent predictors of a high CT-LeSc were: Male sex (OR 1.73; 95 % CI 1.04-2.90) diabetes (OR 2.91; 95 % CI 1.61-5.23), hypertension (OR 2.54; 95 % CI 1.40-4.63), Morise score ≥16 (OR 1.97; 95 % CI 1.06-3.67) and HeartScore ≥5 (OR 2.42; 95 % CI 1.41-4.14). We described a cardiac CT adapted Leaman score as a tool to quantify total (obstructive and nonobstructive) coronary atherosclerotic burden, reflecting the comprehensive information about localization, degree of stenosis and type of plaque provided by CCTA. Male sex, hypertension, diabetes, a HeartScore ≥5 % and a Morise score ≥16 were associated with a high coronary atherosclerotic burden, as assessed by the CT-LeSc. About one fifth of the patients with nonobstructive CAD had a CT-LeSc in the highest tercile, and this could potentially lead to a reclass

    Projetos de inovação e cocriação como fatores de valor económico e social em meio rural

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    A aposta na inovação nas organizações é cada vez mais, um fator chave para a sua sustentabilidade e competitividade As Instituições de Ensino Superior (têm vindo a explorar a metodologia de cocriação para a inovação entre empresas e equipas multidisciplinares de estudantes, potenciando um ambiente de inovação no território Este estudo de caso, baseia-se, fundamentalmente, na análise de conteúdo dos documentos finais de 28 projetos/desafios de cocriação o da inovação, desenvolvidos no âmbito do Programa Demola IPB, relacionados com a produção animal, produção agrícola, uso dos recursos florestais, agroindústrias e sector alimentar, e desenvolvimento rural.info:eu-repo/semantics/publishedVersio

    Diabetes as an independent predictor of high atherosclerotic burden assessed by coronary computed tomography angiography: The coronary artery disease equivalent revisited

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    (1) To study the prevalence and severity of coronary artery disease (CAD) in diabetic patients. (2) To provide a detailed characterization of the coronary atherosclerotic burden, including the localization, degree of stenosis and plaque composition by coronary computed tomography angiography (CCTA). Single center prospective registry including a total of 581 consecutive stable patients (April 2011-March 2012) undergoing CCTA (Dual-source CT) for the evaluation of suspected CAD without previous myocardial infarction or revascularization procedures. Different coronary plaque burden indexes and plaque type and distribution patterns were compared between patients with (n = 85) and without diabetes (n = 496). The prevalence of CAD (any plaque; 74.1 vs. 56 %; p = 0.002) and obstructive CAD (≥50 % stenosis; 31.8 vs. 10.3 %; p<0.001) were significantly higher in diabetic patients. The remaining coronary atherosclerotic burden indexes evaluated (plaque in LM-3v-2v with prox. LAD; SIS; SSS; CT-LeSc) were also significantly higher in diabetic patients. In the per segment analysis, diabetics had a higher percentage of segments with plaque in every vessel (2.6/13.1/7.5/10.5 % for diabetics vs. 1.4/7.1/3.3/4.4 % for nondiabetics for LM, LAD, LCx, RCA respectively; p<0.001 for all) and of both calcified (19.3 vs. 9.2 %, p<0.001) and noncalcified or mixed types (14.4 vs. 7.0 %; p<0.001); the ratio of proximal-to-distal relative plaque distribution (calculated as LM/proximal vs. mid/distal/branches) was lower for diabetics (0.75 vs. 1.04; p = 0.009). Diabetes was an independent predictor of CAD and was also associated with more advanced CAD, evaluated by indexes of coronary atherosclerotic burden. Diabetics had a significantly higher prevalence of plaques in every anatomical subset and for the different plaque composition. In this report, the relative geographic distribution of the plaques within each subgroup, favored a more mid-to-distal localization in the diabetic patients

    A proposal for the evaluation of the bioeconomic efficiency of beef cattle production systems

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    ABSTRACT The objective of this study was to identify types of production system and their main indicators on bioeconomic efficiency, using qualitative and quantitative methods to evaluate beef cattle farms in the western region of the state of Rio Grande do Sul. A survey was carried out with 43 farmers operating in the western region of that state. All farms operated with complete cycle production systems in areas larger or equal to 900 ha. A qualitative questionnaire with binary answers and a quantitative questionnaire with numerical answers were applied. Technology and Management drivers were used for the calculation of the efficiency index of farmers obtained by both questionnaires. Farmers were divided into three clusters: low-efficiency level (LEL), intermediate-efficiency level (IEM), or high-efficiency level (HEL), as a result of the comparison of the scores obtained for the analyzed parameters. Subfactors resulting from each comparison (LEL × IEL; LEL × HEL, and IEL × HEL) were different as a function of the comparison and of the methods applied. Low-efficiency level farmers need to improve essential production processes, such as technology and management, as well as health management practices together with the financial management of the production system. Intermediate-efficiency level farmers need to improve their routine animal management, pasture management, and calculation of financial indicators to become highly efficient. The quantitative method allowed to identify underestimation (39.3%) or overestimation (24.2%) when farmers were are classified in clusters. Different methods may be used, but those based on quantitative information have stronger discrimination power to identify different types of farmers
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