2,656 research outputs found
Los procesos químicos como factores de alteración de materiales petreos empleados en construcción
Is Seasonal Households' Consumption Good for the Nexus Carbon/Water Footprint? the Spanish Fruits and Vegetables Case
Proximity and in-season consumption criteria have been suggested as solutions for fruits and vegetables consumers to drive the economy to a more sustainable development. Using a new concept, seasonal avoided footprint by imports, we disentangle the role of period and country of origin. Although, as a general rule, consumers could reduce the footprint by choosing domestic produce, this is not always the case. Due to the high efficiency of Spanish domestic production in terms of both CO2e and water use (except for scarce water), imports from some regions, like Africa (green beans, peppers, tomatoes, bananas, strawberries, oranges), contribute to significantly increasing both water and carbon impacts. However, a monthly basis analysis shows unsustainable hotspots for domestic production. Importing from France (apples, potatoes) or Portugal (tomatoes, strawberries) reduces both footprints, so Spanish local consumption would be bad for the environment. Hotspots are mainly concentrated in scarce water and, especially, for out-of-season vegetables during 11 months a year (savings up to 389%), nine months for out-of-season fruits, and five months for in-season fruits. The results suggest the difficulty to generalize an easy environmental recommendation based on buying local fruits and vegetables: consumption must be analyzed on monthly/seasonal, product, and country bases
El metamorfismo del sector El Vellon-Pedrezuela (Sistema Central Español)
El presente trabajo aborda el estudio metamorfico del sector «El Vellon - Pedrezuela». Mediante la determinación de los diferentes tipos de paragenesis minerales que contienen los materiales que afloran en este sector (metapelitas. metasamitas. anfibolitas y rocas calcosiiicatadas). de sus relaciones interminerales y de sus penodos de blastesis. se establece un metamorfismo regional progresivo de grado medio. Dicho metamorfismo se caracteriza por unas condiciones de 5.25 Kbar y 550 UC para un periodo de interfase yariando estas durante la segunda fase a 4 4 0.5 Kbar y 600 JC. Ei gradiente metamorfico aumenta di: 26 oC/Km. a 380 4 5 oC/Km desde el periodo de interfase a la segunda fase hercinica
A numerical method for nonlinear age-structured population models with finite maximum age
AbstractWe propose a new numerical method for the approximation of solutions to a non-autonomous form of the classical Gurtin–MacCamy population model with a mortality rate that is the sum of an intrinsic age-dependent rate that becomes unbounded as the age approaches its maximum value, plus a non-local, non-autonomous, bounded rate that depends on some weighted population size. We prove that our new quadrature based method converges to second-order and we show the results of several numerical simulations
Attenuation and diffusion produced by small-radius curvatures in POFs
Our aim is to characterize curvatures using a methodology previously applied to other localized disturbances in plastic optical fibers (POFs). The effects of several curvature radii and turn angles have been analyzed, so that for each condition, angular dependent attenuation and diffusion are obtained from experimental measurements to construct a matrix that accounts for the global effects of power loss and mode mixing introduced by the curvature over the angular power distribution. Power loss as a function of bend radius was calculated using the characteristic matrices and compared to experimental results to validate the model. This curvature model can be a useful tool to predict the impact of bends on transmission properties as is demonstrated in the example of a small network in a domestic environment
El control de los criterios de higiene de los procesos en mataderos de cerdo ibérico como medio para evaluar el funcionamiento aceptable de la producción
La normativa vigente obliga a los mataderos de cerdo ibérico a desarrollar e implantar un plan APPCC (Análisis de Peligros y Puntos de Control Crítico). De igual modo deben comprobar el correcto funcionamiento de su proceso de producción realizando controles microbiologícos de la superficie de las canales, siguiendo un plan de muestreo diseñado de acuerdo al Reglamento 2073/2005. En el presente trabajo se expone el diseño de un plan de muestreo de un matadero de cerdo ibérico, y se muestran los resultados obtenidos en los primeros controles realizados siguiendo dicho plan
Fracture test of a Gothic ribbed vault
A Gothic ribbed vault has been built at the School of Architecture of Madrid in order to investigate the construction complexities of this kind of vaults. The ribbed vault is described in the manuscript of Alonso de Vandelvira, and its shape was reconstructed making using the drawings this architect from the 16th century. The fracture test was carried on by loading the central keystone of the vault until its collapse took place. The experiment was filmed and by doing so, it was possible to observe the failure mechanism of the vault. At the same time, it was interesting to compare this collapse experience with the results obtained using two different me-thods. First, a stability calculation was carried out through graphic statics, and secondly a calcu-lation was performed using the rigid-block analysis method. The focus of this paper is to show and analyze the results of both studies
- …