1,628 research outputs found

    Electricity generation from biogas on swine farm considering the regulation of distributed energy generation in Brazil: a case study for Minas Gerais

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    The objective of this study was to analyze the feasibility of using agricultural waste from a swine farm to produce biogas, which can be used to generate electricity. For this purpose, the waste production potential was evaluated to determine the biogas production capacity of the farm. This measurement allowed scaling the size of the generator used to the electricity production to meet the needs of the farm as well as surplus electricity. The surplus electricity may be used on the farm when the generator is under maintenance or the electricity consumption is larger than the energy generated. This process is regulated by Normative Resolutions 482 and 687 in Brazil. The results of the analysis of the net present value, internal return rate, payback period and benefit cost ratio indicated that the project was feasible

    An assessment of evaluation methods applied in decision support systems for sustainable urban mobility planning

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    The objective of this paper is to discuss procedures for assessing the impacts of different evaluation methods used in systems designed to sustainable urban mobility planning and management. The case studied shows a comparison of the points of view assumed by a small group of experts when using two particular systems. The evaluation methods used in those systems are: Pair-wise Comparisons and Scale of Points. The evaluation was conducted for groups of indicators devised for urban mobility monitoring, which were called Themes. The twenty Themes were also grouped in the following five general Categories: Transport and Environment, Transport Management, Transport Infrastructure, Transport Planning, and Socioeconomic Aspects of Transport. The main conclusions drawn from the application of non-parametric statistical methods for comparing the results of the evaluations suggest that the method Scale of Points could be the most indicated for evaluations with community members in general (experts or non-experts).GRICES (Office for International Relations in Science and Higher Education of the Portuguese Ministry of Science).CNPq (Brazilian National Council for Scientific and Technological Development).FAPESP (Foundation for the Promotion of Science of the State of São Paulo).CAPES (Post-Graduate Federal Agency)

    Otimização da produção de biodiesel a partir de óleo de coco babaçu com aquecimento por microondas

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    As reações sob aquecimento por microondas geralmente apresentam significativa redução no tempo de reação e elevados rendimentos. Portanto, o objetivo desse trabalho foi adaptar um forno de microondas doméstico de forma adequada e segura para realização de reações de transesterificação, e otimizar o processo de produção de biodiesel por microondas usando óleo de coco babaçu como matéria prima. Para este fim, foi usado um planejamento composto central no qual se variou o tempo de irradiação, concentração de KOH e razão óleo:metanol. Análises estatísticas foram feitas para avaliarem a significância do modelo usado. As condições experimentais ótimas foram: razão óleo:metanol, 8,59, concentração de KOH, 2,19%, tempo de irradiação, 70 segundos, dando rendimento de aproximadamente 100%.Reactions under microwave heating present reduced reaction times and larger yields. Therefore, this work is aimed at adapting a domestic microwave oven and optimizing the transesterification reaction used in biodiesel production with microwave heating, using babaçu coconut oil as raw material. It was used a central composite design for varying irradiation time, KOH concentration, and oil:methanol ratio. Statistical analyses were performed in order to assess the significance of the model used. The optimized experimental conditions were: oil:methanol ratio, 8.59; KOH concentration, 2.19 %; and irradiation time, 70 seconds, giving an yield of approximately 100% regarding esters formation.FAPEM

    Bipolar current power supply for the steering beam of the main line of the CV-28 Cyclotron

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    The objective of the beam transport system is to make the accelerated particles reach the targets with specific characteristics and with the desired quality optics, so it is necessary to use remotely commanded devices, such as collimators, quadrupoles lenses and steering magnets

    The Use of MODIS Images to Quantify the Energy Balance in Different Agroecosystems in Brazil

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    Sugarcane (SC) is expanding over coffee (CO), while both crops have replaced the natural vegetation (NV) in the northeastern side of São Paulo (SP) state, Southeast Brazil. Under these dynamic land-use changes, geosciences are valuable tools for evaluating the large-scale energy and mass exchanges between the vegetation and the lower atmosphere. For quantification of the energy balance components in these mixed agroecosystems, MODIS images were used throughout the Simple Algorithm for Evapotranspiration Retrieving (SAFER) algorithm, during the year 2015 in the main sugarcane- and coffee-growing regions of the state. Regarding, respectively, sugarcane, coffee, and natural vegetation, the fractions of the net radiation (Rn) used as latent heat flux (λE) were 0.68, 0.87, and 0.77, while the corresponding ones for the sensible heat (H) fluxes were 0.27, 0.07, and 0.16. Negative H values were noticed from April to July, because of heat advection raising λE values above Rn, but they were more often in coffee than in sugarcane. It was concluded that sugarcane crop presented lower evapotranspiration rates, when compared with coffee, which could be an advantage under the actual water scarcity scenario. However, sugarcane replacing natural vegetation means environmental warming, while the land use changes promoted by coffee crop represented cooling conditions

    Stability of casein micelles cross-linked with genipin: a physicochemical study as a function of pH

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    Chemical or enzymatic cross-linking of casein micelles (CMs) increases their stability against dissociating agents. In this paper, a comparative study of stability between native CMs and CMs cross-linked with genipin (CMs-GP) as a function of pH is described. Stability to temperature and ethanol were investigated in the pH range 2.0-7.0. The size and the charge (ζ\zeta-potential) of the particles were determined by dynamic light scattering. Native CMs precipitated below pH 5.5, CMs-GP precipitated from pH 3.5 to 4.5, whereas no precipitation was observed at pH 2.0-3.0 or pH 4.5-7.0. The isoelectric point of CMs-GP was determined to be pH 3.7. Highest stability against heat and ethanol was observed for CMs-GP at pH 2, where visible coagulation was determined only after 800 s at 140 ^\circC or 87.5% (v/v) of ethanol. These results confirmed the hypothesis that cross-linking by GP increased the stability of CMs.Comment: 5 pages, 2 figures, International Dairy Journal, 201

    Low temperature photoluminescence in ultra-thin germanium quantum wells

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    We measured the photoluminescence (PL) spectra of a series of Gen quantum wells as a function of temperature, from 2K to 50K. The PL spectra at 2.1K are dominated by broad emission lines, which can be interpreted as recombination across the indirect gap of the Si/Ge microstructure and are strongly inuenced by the interface morphology of each sample. Beyond T & 15K, all samples show identical spectra in which the broad structures are replaced by thin, strong lines. We interpret these changes as a quenching of the recpmbination across the gap PL of the microstructure and the appearance of defect-related peaks from the Si substrate

    Effect of the sequential application of glyphosate in Commelina benghalensis and Commelina dif/usa control in coffee crop

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    A fim de estabelecer estratégias que reduzam a tolerância de Commelina benghalensis e C. diffusa ao glyphosate, foram realizados dois experimentos lavoura de café. Foi avaliado o efeito da aplicação seqüencial de doses crescentes de glyphosate, comparando com as formulações de glyphosate SA (sal isopropilamina) e WG (sal amônio) no controle destas espécies e a toxicidade causada à cultura. Não foi observada diferença significativa entre as formulações glyphosate SA (2160 g/ha e.a.) e WG (2160 g/ha e.a.), no controle de C. diffusa e C. benghalensis. A aplicação seqüencial de glyphosate WG, nas doses de 1440 e 1080 g/ha e.a., com a segunda aplicação 21 dias após a primeira, demonstrou controle eficiente de C. diffusa e C. benghalensis, até os 100 dias após a aplicação (DAA). A mistura no tanque glyphosate SA + 2,4-D na dose de 1080/1 005 g/ha e.a. e a mistura diuronlparaquat na dose de 300/600 g/ha, proporcionaram injúria acentuada ao cafeeiro até os 60 DAA. No entanto, glyphosate SA e glyphosate WG em aplicação seqüencial ou em única aplicação, nas doses estudadas, ocasionou injúria acentuada ao cafeeiro até os 30 DAA, passando para injúrias leves nas avaliações seguintes. Different strategies to reduce C. benghalens is and C. diffusa tolerance to glyphosate were studied in two field experiments in coffee. The effect of glyphosate sequential application at increasing doses and comparing the glyphosate formulations, glyphosate SA (isopropilamine salt) and glyphosate WG (ammonium salt) in the control ofthese species and the respective phytotoxicity was evaluated. No significant difference were foundamong formulations of glyphosate SA (2160 g/ha a.e.) and glyphosate WG (2160 g/ha a.e.), in C. diffusa and C. benghalensis controI. The sequential application of glyphosate WG at 1440 and 1080 g/ha a.e., with the second application 21 days after the first, was efficient for C. diffusa and C. benghalensis control, from 30 to 100 days after application (DAA). The tank mixture glyphosate SA+2,4-D, at 1080 + 1005 g/ha a.e., and the mixture diuron/paraquat at 300/600 g/ha resulted in accentuated phytotoxicity until 60 DAA. However, glyphosate SA and glyphosate WG in sequential application or in unique application, in the studied doses, caused accentuated phytotoxicity until 30 DAA, tuming to light phytotoxicity in the folIowing evaluations.

    Atividade antimicrobiana de subfrações padronizadas da planta Arrabidaea chica Verl.

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    Este estudo analisou o potencial terapêutico de extratos e subfrações padronizadas da planta amazônica Arrabidaea chica, visando seu uso tópico como medicamento e eficácia comprovada em doenças cutâneas
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