Fractal analysis of weld defect patterns obtained by radiographic tests

This paper presents a fractal analysis of radiographic patterns obtained from specimens with three types of inserted welding defects: lack of fusion, lack of penetration, and porosity. The study focused on patterns of carbon steel beads from radiographs of the International Institute of Welding (IIW). The radiographs were scanned using a greyscale with 256 levels, and the fractal features of the surfaces constructed from the radiographic images were characterized by means of Hurst, detrended-fluctuation, and minimal-cover analyses. A Karhunen-Loeve transformation was then used to classify the curves obtained from the fractal analyses of the various images, and a study of the classification errors was performed. The obtained results indicate that fractal analyses can be an effective additional tool for pattern recognition of weld defects in radiographic tests.Comment: 7 pages, 2 figures. To appear AIP Conference Proceedings - QNDE 200

Chemical composition and activity of a biofilm during the start-up of an airlift reactor

For the successful operation of a biofilm reactor, it is important to characterise the fixed biomass, its activity and composition. The purpose of this research was to monitor the biofilm characteristics of an airlift reactor, namely its composition in terms of exopolymers (polysaccharides and proteins), attached biomass, thickness, total proteins, as well as its activity in terms of substrate consumption rates. During the early phases of biofilm development, a high exopolymer production was observed, which helped in promoting the initial cell adhesion. The high turbulence with strong abrasive conditions might also trigger the excretion of those polymers. Low levels of extracellular proteins were detected, showing that the proteins in the biofilm were mainly intracellular. The biofilm accumulation on the carrier was accompanied by an increased biological activity; however, at the end of the experiment, the specific substrate consumption rate decreased, probably because of a reduction of the cell density within the biofilm.Fundação para a Ciência e a Tecnologia (FCT) – PRAXIS XXI/BM/6699/95

Biological kinetics parameters in a pure culture biofilm developed in an airlift reactor

A diffusion-reaction model was fitted to data obtained with Pseudomonas fluorescens biofilms developed in an airlift reactor under different limiting substrate conditions, in order to determine the biofilm kinetic constants and the substrate concentration profiles within the biological films. Model predicted concentration profiles within the biofilms demonstrate that all films were completely penetrated by the substrate and that the reaction rate inside the biofilms was of zero order. The estimated kinetic constants (μmax = 0.24 h-1; Ks = 0.73x10-3 kg/m3) differ from those obtained in a suspended culture (μmax= 0.31 h-1; Ks = 6.21 kg/m3), as a result of the different metabolic state of microorganisms within biofilms

Avaliação do potencial mineiro das escombreiras da mina de São Domingos, Faixa Piritosa Ibérica, Portugal

ABSTRACT: The outcropping São Domingos Iberian Pyrite Belt deposit was mined since Roman time and between 1857 and 1966. The mine is formed by a 120 m depth flooded open pit and galleries until 420 m depth. Associated with felsic volcanic rocks and black shales of the Volcano-Sedimentary Complex, the deposit is formed by massive sulphide and stockwork ore (py, ccp, sp, ga, tt, apy) and related supergene enrichment ore (hematite gossan and covellite/chalcocite). Different mine wastes classes were mapped: gossan, felsic volcanic and shales, shales and landfill. Considering the CONASA mining waste characterization (162 shafts and 160 reverse circulation boreholes/LNEG database), new inferred resources are presented, using block modelling software: 2.38 Mt @ 0.77 g/t Au and 8.26 g/t Ag in non-conditioned volumes. Considering all evaluated wastes, including urban areas, an inferred resource of 4.0 Mt @ 0.64 g/t Au and 7.30 g/t Ag is presented, corresponding to a metal content of 82,878 oz t Au and 955,753 oz t Ag.RESUMO: Localizado na Faixa Piritosa Ibérica, o jazigo de São Domingos foi explorado na época Romana e no período entre 1857 e 1966, tendo sido escavada uma corta com 120 m de profundidade e abertas galerias mineiras até 420 m. O minério é formado por sulfuretos maciços e stockwork (py, ccp, sp, ga, tt, apy) e respetivo enriquecimento supergénico (chapéu de ferro hematítico e zona de covelite/calcocite), encontrando-se associado a rochas vulcânicas félsicas e xistos negros do Complexo Vulcano-Sedimentar. Cartografaram-se diferentes classes de escombreiras: chapéu de ferro, rochas vulcânicas e xistos, xistos e aterros. Considerando a sua caracterização efetuada pela empresa CONASA (162 poços e 160 sondagens de circulação inversa/base de dados LNEG), foram inferidos novos recursos usando software de modelação por blocos: 2,38 Mt @ 0,77 g/t Au e 8,26 g/t Ag (volumes não condicionados). Considerando todos os recursos avaliados (incluindo áreas urbanas) inferem-se valores de 4,0 Mt @ 0.64 g/t Au e 7,30 g/t Ag, correspondendo a um conteúdo em metal de 82 878 oz t Au e 955 753 oz t Ag.info:eu-repo/semantics/publishedVersio

A modular web-based software solution for mobile networks planning, operation and optimization

Mobile networks management is increasingly critical due to heavy communications usage by customers and complex due to the multiple technologies and systems deployed. Thus, Mobile Network Operators (MNOs) are constantly looking for better software solutions and tools to help them increase network performance and manage their networks more efficiently. In this paper, we present a modular web-based software solution to tackle problems related to mobile network planning, operation and optimization. The solution is focused on a set of functional requirements carefully chosen to support the network life cycle management, from planning to Operation and Maintenance (OAM) and optimisation stages. Based on a 3-tier modular architecture and implemented using only open-source software, the solution handles multiple data sources (e.g., Drive Test (DT) and Performance Management (PM)) and multiple Radio Access Network (RAN) technologies. MNOs can explore all available data through a flexible and user-friendly web interface, that also includes map-based visualization of the network. Moreover, the solution incorporates a set of recently developed and validated RAN algorithms, supporting tasks of network diagnosis, optimization, and planning. Also, with the purpose of optimizing the network, MNOs can investigate network simulations, using the RAN algorithms, of how the network will behave under certain conditions, and visualize the outcome of those simulations.info:eu-repo/semantics/publishedVersio

Monitoring cell detachment by surfactants in a parallel plate flow chamber

The efficacy of the surfactants SDS and CTAB in detaching P. fluorescens from glass surface was evaluated in a parallel plate flow chamber. This device enables “in situ” determinations of cells detachment following the application of surfactants under well controlled hydrodynamic conditions. The results showed that SDS was able to remove almost all adhering bacteria in a short period of time, whereas CTAB did not promote much cell desorption. On the contrary, this surfactant increased the adhesion strength between cells and glass. Both surfactants promoted different alterations of cell surface properties, which explains their dissimilar effectiveness as cleansing agents.programme SAPIEN

From Fundamental Strings to Small Black Holes

We give evidence in favour of a string/black hole transition in the case of BPS fundamental string states of the Heterotic string. Our analysis goes beyond the counting of degrees of freedom and considers the evolution of dynamical quantities in the process. As the coupling increases, the string states decrease their size up to the string scale when a small black hole is formed. We compute the absorption cross section for several fields in both the black hole and the perturbative string phases. At zero frequency, these cross sections can be seen as order parameters for the transition. In particular, for the scalars fixed at the horizon the cross section evolves to zero when the black hole is formed.Comment: 36 pages, 4 figures, argument about minimally coupled scalar absorption cross section clarifie