2,475 research outputs found

    Valor nutritivo de silagens de bagaço de sorgo sacarino produzido na Beira Interior Sul

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    Pelas utilizações diversificadas que lhe estão associadas, o sorgo sacarino (Sorghum bicolor (L.) Moench) é uma cultura que tem vindo a receber assinalável atenção nos meios académicos. Apesar de em regra ser encarada como uma matéria-prima para a produção de biocombustíveis, nomeadamente bioetanol, a verdade é que a cultura e os seus subprodutos, designadamente a fração fibrosa da planta, apresentam a capacidade de ser utilizados com outros fins, nomeadamente na alimentação de ruminantes. O objetivo deste estudo foi comparar o valor nutritivo da silagem de bagaço de três cultivares de sorgo sacarino (Sugargraze, Sugar-T e 23402), com o valor nutritivo da silagem das mesmas cultivares processadas sem e com pré-fenação. Os resultados obtidos (% na MS) para as silagens de sorgo sacarino sem pré-fenação vs silagens de sorgo sacarino com pré-fenação vs silagens de bagaço de sorgo sacarino foram, respetivamente, os seguintes: MS 23,23% (±2,045) vs 26,52% (±1,233) vs 28,56% (±4,115) (P<0,05); PB 6,47% (±0,589) vs 5,96% (±0,164) vs 4,81% (±0,392) (P<0,05); GB 1,11% (±0,084) vs 1,01% (±0,096) vs 0,86% (±0,041) (P<0,05); NDF 55,05% (±2,613) vs 54,39% (±0,638) vs 74,53% (±1,283) (P<0,05); ADF 31,16% (±1,530) vs 31,76% (±0,725) vs 45,46% (±1,073) (P<0,05); ADL 3,22% (±0,497) vs 3,39% (±0,708) vs 4,87% (±0,474) (P<0,05); Cinzas 4,41% (±0,437) vs 4,33% (±0,489) vs 3,17% (±0,263) (P<0,05); Digestibilidade da MO 59,25% (±1,584) vs 59,40% (±1,708) vs 48,32% (±0,988) (P<0,05). Estes resultados levam-nos a concluir que as silagens de bagaço de sorgo sacarino apresentam valores de PB, GB e Digestibilidade da MO mais baixos (P<0,05) e valores de NDF, ADF e ADL mais elevados (P<0,05). No entanto, parecem apresentar valor nutritivo adequado para serem utilizadas na alimentação de ruminantes. Serão necessários estudos futuros para avaliar o efeito da utilização deste subproduto na produção de leite e carne

    Static Hopfions in the extended Skyrme-Faddeev model

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    We construct static soliton solutions with non-zero Hopf topological charges to a theory which is an extension of the Skyrme-Faddeev model by the addition of a further quartic term in derivatives. We use an axially symmetric ansatz based on toroidal coordinates, and solve the resulting two coupled non-linear partial differential equations in two variables by a successive over-relaxation (SOR) method. We construct numerical solutions with Hopf charge up to four, and calculate their analytical behavior in some limiting cases. The solutions present an interesting behavior under the changes of a special combination of the coupling constants of the quartic terms. Their energies and sizes tend to zero as that combination approaches a particular special value. We calculate the equivalent of the Vakulenko and Kapitanskii energy bound for the theory and find that it vanishes at that same special value of the coupling constants. In addition, the model presents an integrable sector with an infinite number of local conserved currents which apparently are not related to symmetries of the action. In the intersection of those two special sectors the theory possesses exact vortex solutions (static and time dependent) which were constructed in a previous paper by one of the authors. It is believed that such model describes some aspects of the low energy limit of the pure SU(2) Yang-Mills theory, and our results may be important in identifying important structures in that strong coupling regime.Comment: 22 pages, 42 figures, minor correction

    Retrofitting strategies for improving the energy and environmental efficiency in industrial furnaces: A case study in the aluminium sector

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    This study aims to analyse some of the most relevant issues that the energy intensive industry needs to face in order to improve its energy and environmental performance based on innovative retrofitting strategies. To this end, a case study based on the aluminium industry, as one of the most relevant within the European energy intensive industry has been thoroughly discussed. In particular, great efforts must be addressed to reduce its environmental impact; specifically focusing on the main stages concerning the manufacturing of an aluminium billet, namely alloy production, heating, extrusion and finishing. Hence, an innovative DC (direct current) induction technology with an expected 50% energy efficiency increase is used for retrofitting conventional techniques traditionally based on natural gas and AC (alternating current) induction. A life cycle assessment was applied to analyse three different scenarios within four representative European electricity mixes. The results reported reductions up to 8% of Green House Gases emissions in every country. France presented the best-case scenario applying only DC induction; unlike Greece, which showed around 150% increment. However, the suitability of the new DC induction technology depends on the electricity mix, the technological scenario and the environmental impact indicators. Finally, environmental external costs were assessed with comparison purposes to evaluate the increase of energy and environmental efficiency in existing preheating and melting industrial furnaces currently fed with natural gas

    Battery Manufacturing Resource Assessment to Minimise Component Production Environmental Impacts

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    A promising route to attain a reliable impact reduction of supply chain materials is based on considering circular economy approaches, such as material recycling strategies. This work aimed to evaluate potential benefits of recycling scenarios for steel, copper, aluminium and plastic materials to the battery manufacturing stage. Focused on this aim, the life cycle assessment (LCA) and the environmental externalities methodologies were applied to two battery study cases: lithium manganese oxide and vanadium redox flow (VRFB) batteries, based on a cradle-to-gate LCA approach. In general, the results provided an insight into the raw material handling route. Environmental impacts were diminished by more than 20% in almost all the indicators, due to the lower consumption of virgin materials related to the implemented recyclability route. Particularly, VRFB exhibited better recyclability ratio than the Li-ion battery. For the former, the key components were the periphery ones attaining around 70% of impact reduction by recycling steel. Components of the power subsystem were also relevant, reaching around 40% of environmental impact reduction by recycling plastic. The results also foresaw opportunities for membranes, key components of VRFB materials. Based on findings, recycling strategies may improve the total circularity performance and economic viability of the studied systems

    High-temperature PCM-based thermal energy storage for industrial furnaces installed in energy-intensive industries

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    The energy considered as waste heat in industrial furnaces owing to inefficiencies represents a substantial opportunity for recovery by means of thermal energy storage (TES) implementation. Although conventional systems based on sensible heat are used extensively, these systems involve technical limitations. Latent heat storage based on phase change materials (PCMs) results in a promising alternative for storing and recovering waste heat. Within this scope, the proposed PCM-TES allows for demonstrating its implementation feasibility in energy-intensive industries at high temperature range. The stored energy is meant to preheat the air temperature entering the furnace by using a PCM whose melting point is 885 °C. In this sense, a heat transfer model simulation is established to determine an appropriate design based on mass and energy conservation equations. The thermal performance is analysed for the melting and solidification processes, the phase transition and its influence on heat transference. Moreover, the temperature profile is illustrated for the PCM and combustion air stream. The obtained results prove the achievability of very high temperature levels (from 700 to 865 °C) in the combustion air preheating in a ceramic furnace; so corroborating an energy and environmental efficiency enhancement, compared to the initial condition presenting an air outlet at 650 °C

    Associative study between handgrip strength, body composition and functional fitness in healthy elderlies

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    Poor handgrip strength is associated with [1,2]. As far as our understanding goes, [1] elderly’s disability independent elderlies trend to have high levels of quality of life . Even more, body composition and functional fitness presents [2] association with quality of life . OBJECTIVE: Thus, the aim of this study was to assess the associations between body composition, functional fitness and handgrip strength. METHODS: It was hypothesized that handgrip strength is associated with elderly’s body composition and functional fitness. Forty-eight elderly subjects (10 males and 38 females) with 69.61 (± 4.21) years old volunteered for this study. All the procedures were in accord to the Helsinki’s declaration regarding human research. The handgrip strength was measured with a digital mechanical dynamometer (CAMRY, New York, USA). The functional fitness was assessed by the functional fitness [3] test . The body composition was evaluated by a bioimpedance balance (Tanita, BC-601, Illinois, USA). The spearmen’s test allowed to assess the significant associations between the handgrip strength, functional fitness and body composition.info:eu-repo/semantics/publishedVersio

    Implementation of PEF treatment at real-scale tomatoes processing considering LCA methodology as an innovation strategy in the agri-food sector

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    In Europe, science and innovation are boosting the agri-food sector and, in parallel, are helping to decrease greenhouse gas emissions (GHG) and European dependency on non-renewable resources. Currently, it is well-known that this sector contributes to the consumption of energy and material resources, causing significant environmental impacts that require a complex and comprehensive environmental evaluation in order to manage them effectively. This becomes even more complicated when new technologies are reaching the level of technological maturity needed to be installed in the production lines. To address this scientific challenge, the life cycle assessment (LCA) has been used in this paper to evaluate the potential of pulsed electric fields (PEF) technology at an industrial scale to facilitate the steam peeling of tomato fruits. Considering the thermo-physical peeling stage, the LCA has shown that PEF technology is environmentally friendly, because when PEF technology is applied, all the considered environmental indicators improve between 17% and 20%
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