Global magnetic attitude control of spacecraft in the presence of gravity gradient

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Non-Asymptotic Kernel-based Parametric Estimation of Continuous-time Linear Systems

In this paper, a novel framework to address the problem of parametric estimation for continuous-time linear time-invariant dynamic systems is dealt with. The proposed methodology entails the design of suitable kernels of non-anticipative linear integral operators thus obtaining estimators showing, in the ideal case, \u201cnon-asymptotic\u201d (i.e., \u201cfinite-time\u201d) convergence. The analysis of the properties of the kernels guaranteeing such a convergence behaviour is addressed and a novel class of admissible kernel functions is introduced. The operators induced by the proposed kernels admit implementable (i.e., finite-dimensional and internally stable) state-space realizations. Extensive numerical results are reported to show the effectiveness of the proposed methodology. Comparisons with some existing continuous-time estimators are addressed as well and insights on the possible bias affecting the estimates are provided

Effect of cooking and fruit ripening of papaya (Carica papaya L.) on quality of papaya in syrup

El presente trabajo tiene como objetivo estudiar el efecto del grado de maduración de la fruta y la cocción sobre la retención de calcio y la firmeza del mamón en almíbar. Para los ensayos se emplearon frutas en dos grados de maduración distintos. La elaboración de frutas en almíbar se realizó con un tratamiento previo. El pre-tratamiento consistió en impregnar la fruta en soluciones isotónicas de lactato de calcio y la cocción se realizó en solución de sacarosa. Además se realizaron ensayos de elaboración del producto por cocción de frutas verdes frescas, sin pre-tratamiento, en almíbar con adición de 1,5% de lactato de calcio y en almíbar sin adición de calcio. Se midió el contenido de calcio y la firmeza en la fruta fresca, pre-tratada y pos-cocción. Los resultados experimentales indicaron que durante el pre-tratamiento las frutas verde y madura ganan 84,1 y 103,2 mg Ca/100g fruta fresca, respectivamente. Durante la cocción se retiene un 52,8% y 65,6% del calcio ganado, en fruta verde y madura respectivamente. El proceso de cocción de fruta verde en almíbar con lactato de calcio generó un producto con una ganancia de calcio de 78,6 mg Ca/100 g de fruta fresca y la cocción en almíbar (sin calcio) mantuvo los valores del contenido de calcio de la fruta fresca. El pre-tratamiento con calcio incrementa la firmeza de la fruta; la posterior cocción en almíbar favorece la firmeza en el caso de la fruta madura pero disminuye marcadamente la firmeza de la fruta verde.Fil: Lovera, Nancy Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones En Criotecnología de Alimentos (i); Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; ArgentinaFil: Ramallo, Laura A.. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; ArgentinaFil: Salvadori, Viviana Olga. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones En Criotecnología de Alimentos (i); Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentin

Life cycle assessment of a renewable energy system with hydrogen-battery storage for a remote off-grid community

Remote areas usually do not have access to electricity from the national grid. The energy demand is often covered by diesel generators, resulting in high operating costs and significant environmental impacts. With reference to the case study of Ginostra (a village on a small island in the south of Italy), this paper analyses the environmental sustainability of an innovative solution based on Renewable Energy Sources (RES) integrated with a hybrid hydrogen-battery energy storage system. A comparative Life Cycle Assessment (LCA) has been carried out to evaluate if and to what extent the RES-based system could bring environmental improvements compared to the current diesel-based configuration. The results show that the impact of the RES-based system is less than 10% of that of the current diesel-based solution for almost all impact categories (climate change, ozone depletion, photochemical ozone formation, acidification, marine and terrestrial eutrophication and fossil resource use). The renewable solution has slightly higher values only for the following indicators: use of mineral and metal resources, water use and freshwater eutrophication. The climate change category accounts for 0.197 kg CO2 eq./kWh in the renewable scenario and 1.73 kg CO2 eq./kWh in the diesel-based scenario, which corresponds to a reduction in GHG emissions of 89%. By shifting to the RES-based solution, about 6570 t of CO2 equivalent can be saved in 25 years (lifetime of the plant). In conclusion, the hydrogen-battery system could provide a sustainable and reliable alternative for power supply in remote areas

A Comparison of Methods for Excluding Light from Stems to Evaluate Stem Photosynthesis

Premise A comparison of methods using different materials to exclude light from stems to prevent stem CO2 exchange (i.e., photosynthesis), without affecting stem conductance to water vapor, surface temperature, and relative humidity, was conducted on stems of avocado trees in California. Methods and Results The experiment featured three materials: aluminum foil, paper-based wrap, and mineral-based paint. We examined stem CO2 exchange with and without the light exclusion treatments. We also examined stem surface temperature, relative humidity, and photosynthetic active radiation (PAR) under the cover materials. All materials reduced PAR and stem CO2 exchange. However, aluminum foil reduced stem surface temperature and increased relative humidity. Conclusions Methods used to study stem CO2 exchange through light exclusion have historically relied on methods that may induce experimental artifacts. Among the methods tested here, mineral-based paint effectively reduced PAR without affecting stem surface temperature and relative humidity around the stem