António Araújo

Erratum to: Suspended solids in freshwater systems: characterisation model describing potential impacts on aquatic biota

Purpose High concentration of suspended solids (SS)—fine fraction of eroded soil particles—reaching lotic environments and remaining in suspension by turbulence can be a significant stressor affecting the biodiversity of these aquatic systems. However, a method to assess the potential effects caused by SS on freshwater species in the life cycle impact assessment (LCIA) phase still remains a gap. This study develops a method to derive endpoint characterisation factors, based on a fate and effect model, addressing the direct potential effects of SS in the potential loss of aquatic invertebrate or algae and macrophyte species.

Monte Carlo simulations of ambient temperature uncertainty determined by dual-band pyrometry

The Monte Carlo technique for uncertainty propagation was used to estimate the uncertainty of ambient temperature measurements, obtained by dual-band pyrometry, of assumed grey surfaces. A large number of simulations were performed for a wide range of values from the following parameters: uncertainty of the detectors, emissivity of the target surface, background temperature of the surrounding surfaces, and spectral characteristics of the detectors (bandwidth, location of the bands, and distance between bands). Temperature measurement uncertainties from single-band pyrometry were also simulated for evaluation against dual-band uncertainties. It is concluded that the following parameters minimize dual-band temperature uncertainty: narrow wavelength bands, far apart from each other, positioned towards low wavelengths; low surface emissivity; high or low background temperature with respect to the target surface temperature (uncertainty grows very fast as the background and target temperatures converge, and tends to a constant minimum value as the background and target temperatures diverge).

The Carbon Footprint of Ceramic Products

Nowadays it is generally recognized that human activities increase anthropogenic greenhouse gas (GHG) emissions to dangerous thresholds, leading to climate change due to an increase in global temperatures. In an industrial context, the product carbon footprint concept has been emerging as a relevant tool to support the development and implementation of GHG management strategies throughout product life cycles, in order to reduce GHG emissions along the supply chain, improve energy efficiency, and improve product competitiveness in different markets. This chapter focuses on the carbon footprint of ceramic products and has the following purposes: (1) to present general information on ceramic manufacturing, in particular a characterization of the European ceramic industry with regard to energy sources and production value, and a description of the general ceramic manufacturing process; (2) to carry out case studies in which the carbon footprint of different ceramic products (ornamental earthenware piece, brick, roof tile, wall and floor tile, sanitary ware) is quantified; (3) to identify improvement measures and best available techniques (BAT) to reduce the total carbon footprint of some products; (4) to analyze the specific GHG emission of each of the ceramic products studied, considering a cradle-to-gate approach; and (5) to present some methodological challenges related to carbon footprint quantification.

Investigation of the role of dislocation motion in the generation of acoustic emission from metal cutting

Abstract Due to the very high strain rates and temperatures encountered in metal cutting, opposing viscous damping forces are the dominant mechanism governing dislocation movement, which is the main mechanism for plastic deformation in metals. However, although viscous damping governs the physics of metal deformation, it is concluded that the detected high frequency acoustic emission (AE) signals arising from metal cutting can only be generated owing to the interaction between moving dislocations and obstacles. This would appear to be the reason why the amplitude of the AE signal cannot be directly related to the cutting power, since it arises from a different generation mechanism. As a result, a qualitative model relating the AE to basic deformation parameters was derived, in which the power of the AE is expected to increase with strain and strain rate, but to decrease with temperature. In addition, the frequency content of the AE is expected to increase with strain rate, to decrease with temperature, and to remain unchanged with strain. These results were validated against data from experimental cutting tests and seem to suggest that the generation of the AE during metal cutting is very heavily dependent on dislocation motion.