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Sirvi Autor "Barros, M.M." järgi

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  • Pisipilt
    Kirje
    Economic viability of different skeleton pruning-based management approaches in coffee (Coffea arabica L)
    (Estonian University of Life Sciences, 2026) Silva, F.C.; Paula, V.R.; Sabino, G.B.; Belem, A.L.; Cunha, J.P.B.; Barros, M.M.
    Coffee is one of the most valuable commodities on the international market, and its cultivation is among the most important agricultural activities in Brazil. Skeleton pruning is used in coffee crops to maintain production capacity by promoting the recovery of weakened plants and correcting problems related to plant architecture. This study evaluated the effects of different coffee skeleton-pruning management approaches on operating cost, productivity, and profitability. The experiment was conducted in a 22-year-old field of the cultivar Catuaí Vermelho IAC 144, spaced at 2.8×1.0 m. The treatments were obtained by combining two types of skeletonization and four types of regrowth management, totaling eight treatments plus a control without skeletonization. The experiment was arranged in a randomized block design with six replications, totaling 54 experimental plots. Operational cost was estimated from the time required for each management practice and the corresponding fuel consumption. The results showed that skeletonization restricted to branches between rows stimulated the growth of plagiotropic branches between plants, whereas total skeletonization promoted the greatest vegetative recovery and the highest productivity. Although total skeletonization resulted in higher crop cost, the treatment combining total skeletonization with sprout control showed the best economic performance, with an increase in profitability of up to USD 6,300.00 ha⁻¹ compared with the control.
  • Pisipilt
    Kirje
    Productive efficiency and density and viscosity studies of biodiesels from vegetable oil mixtures
    (2021) Correia, R.C.B.; Silva, F.C.; Barros, M.M.; Maria, A.C.L.; Cecchin, D.; Souza, L.A.; Carmo, D.F.
    Currently in Brazil the minimum content of biodiesel in mixtures is 11% and, according to Brazilian laws, the goal is to reach 15% in volume in diesel fuel available for final consumers by 2023. Therefore, studies about different matrices of biodiesel and distinct mixtures are essential. The present work had two goals, the first one was to analyse physico-chemical properties of 16 biofuels produced from soybean and cotton oils, using S10 diesel, in mixtures B8, B10, B20 and B30. The second goal was to verify the vantages and disadvantages of biodiesel production through prior mixing of the oils, before and after the transesterification process. All biofuels produced presented results of specific mass values at 20 °C and kinematic viscosity at 40 °C within the limits established by ANP Resolution no 30/2016 and International Resolutions. The soybean B20 biofuel showed the best overall results, with the second highest production yield of 65.36%, the fifth lowest kinematic viscosity with 3.48 mm s -1 . The mixture of soybean and cotton oils before the transesterification process presented the highest production yield when compared with the production from a single oil or biodiesel mixtures. The results found proved to be satisfactory and corroborate to continue with the increase of biodiesel in the mixture with diesel to B15 until 2023 and support the possibility of planning for a gradual increase of this mixture in the following years.
  • Pisipilt
    Kirje
    Response surface for biodiesel production from soybean oil by ethylic route
    (2020) Souza, L.A.; Silva, F.C.; Maria, A.C.L.; Belem, A.L.; Cecchin, D.; Barros, M.M.
    Petroleum has been the most consumed energy source in the world, but it tends to run out due its non-renewable character. Among biofuels, biodiesel has emerged as the main candidate to substitute petroleum diesel. The present study aimed to identify the maximum yield point of biodiesel production by generating a response surface using molar ratio, temperature and agitation time as independent variables, and yield as a dependent variable. From the response surface, it is observed that the increase in temperature and reaction time leads to reduced yield. The configuration that resulted in maximum yield of 93.30% was 12:1 molar ratio, 30 °C temperature and 30-minute reaction time. From the chromatographic analysis it was possible to identify five different fatty acids in the composition of the biodiesels. Total saturated fatty acids (palmitic and stearic acids) ranged from 41.53% to 42.09% and total unsaturated fatty acids including monounsaturated and polyunsaturated fatty acids (oleic, linoleic and linolenic acids) ranged from 57.92% to 58.48%. According to the results of the physicochemical analyses, the specific mass at 68°F is in agreement with Brazilian, American and European specifications, ranging from 877.46 kg m-3 to 879.64 kg m-3 . The kinematic viscosity at 104 °F ranged from 4.49 mm² s -1 to 4.82 mm² s -1 . The acid value obtained did not vary within the limits established by the norms, and values between 0.54 and 2.74 mg KOH g -1 were observed.