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- 3-D Characterisation of Nonwoven Fabrics by means of an optical systemPublication . Pereira, Mário José Teixeira; Salvado, Rita; Fiadeiro, Paulo; Silvy, JacquesThe characterisation of fabric structure by means of quantified parameters is essential for the control of the fabrication processes and the resulting properties of the nonwoven materials. Important parameters of the structure are the porosity, the mean pore size and the pore size distribution, the specific area of the texture, the fibres orientation the last one needing to be characterised in the three dimension of the fabric web. In this research work we intend to evaluate the porous fibres orientation in geotextiles nonwovens using a procedure based on the fibres light conducting and their associated scattering. The interpretation of the phenomena is made through a modelisation concept of the pore fibre interfaces
- 3-Form Cosmology: Phantom Behaviour, Singularities and InteractionsPublication . Morais, João; Bouhmadi Lopez, Mariam; Marto, JoãoThe latest cosmological observations by the Planck collaboration (and combined with others) are compatible with a phantom-like behaviour (w < − 1) for the dark energy equation of state that drives the current acceleration of the Universe. With this mindset, we look into models where dark energy is described by a 3-form field minimally coupled to gravity. When compared to a scalar field, these models have the advantage of more naturally accommodating a cosmological-constant and phantom-like behaviours. We show how the latter happens for a fairly general class of positive-valued potentials, and through a dynamical system approach, we find that in such cases the 3-form field leads the Universe into a Little Sibling of the Big Rip singular event into the future. In this work, we explore the possibility of avoiding such singularity via an interaction in the dark sector between cold dark matter and the 3-form field. For the kind of interactions considered, we deduce a condition for replacing the LSBR by a late time de Sitter phase. For specific examples of interactions that meet this condition, we look for distinctive imprints in the statefinder hierarchy { S 3 ( 1 ) ; S 4 ( 1 ) } , { S 3 ( 1 ) ; S 5 ( 1 ) } , and in the growth rate of matter, e ( z ) , through the composite null diagnostic (CND).
- Absorption Ångström exponents of aerosols and light absorbing carbon (LAC) obtained from in situ data in Covilhã, central PortugalPublication . Mogo, Sandra; Cachorro, Victoria; de Frutos, Ángel M; Rodrigues, A.A field campaign was conducted from October 2009 to July 2010 at Covilhã, a small town located in the region of Beira Interior (Portugal) in the interior of the Iberian Peninsula. The ambient light-absorption coefficient, σ(a) (522 nm), obtained from a Particle Soot Absorption Photometer (PSAP), presented a daily mean value of 12.1 Mm⁻¹ (StD = 7.3 Mm⁻¹). The wavelength dependence of aerosol light absorption is investigated through the Ångström parameter, α(a). The α(a) values for the pair of wavelengths 470-660 nm ranged from 0.86 to 1.47 during the period of measurements. The PSAP data were used to infer the mass of light absorbing carbon (LAC) and the daily mean varied from 0.1 to 6.8 μg m⁻³. A detailed study of special events with different aerosol characteristics is carried out and, to support data interpretation, air masses trajectory analysis is performed.
- Absorption coefficients of aerosols obtained from in situ data in Covilhã, central PortugalPublication . Mogo, Sandra; Cachorro, Victoria; De Frutos, Ángel MSince October 2009 an aerosol measurement data set was started at Covilhã, a small town located in the region of Beira Interior (Portugal) ain the interior a of the Iberian Peninsula. a Until July 2010, the ambient light-absorption coefficient, σ (470 nm), σ (522 nm) and σ (660 nm), presented a daily mean value of 14.2Mm-1 (StD=8.6Mm-1), 12.1Mm-1 (StD=7.3Mm-1) and 9.6Mm-1 (StD=5.7Mm-1), respectively. Monthly variations and daily cycle are presented in this work.
- Adaptação do Questionário Standardized Patient Evaluation of Eye Dryness para Português (SPEED-Vp) numa População Não ClínicaPublication . Sanches, Ana Lúcia; Leite, Sara Gisela; Nunes, António; Caixinha, Miguel; Monteiro, Pedro; Nunes, AméliaIntrodução: O objetivo deste estudo foi traduzir e adaptar o questionário Standardized Patient Evaluation of Eye Dryness para o português europeu, bem como avaliar o desempenho psicométrico da versão traduzida, incluindo repetibilidade e concordância. Material e métodos: O questionário original Standardized Patient Evaluation of Eye Dryness - SPEED foi traduzido e adaptado para o contexto cultural português seguindo uma metodologia cientificamente válida comumente usada no processo de adaptação de instrumentos para outras culturas e línguas. O questionário resultante da tradução para o novo idioma foi sujeito a um pré-teste onde os comentários dos participantes foram escritos e considerados para a versão final do questionário. Para a validação da escala da versão final do questionário traduzido, 89 indivíduos de uma população não clínica, com idades entre 18 e 84 anos, foram convidados a responder ao questionário (61% eram mulheres). Uma semana depois, o mesmo questionário foi repetido por 63 indivíduos. A confiabilidade interna do questionário foi analisada pelo alfa de Cronbach, a estabilidade temporal pelo teste-reteste e a análise de concordância entre medidas pelo método de Bland-Altman. Resultados: A consistência interna do questionário traduzido, SPEED-vP, foi alta (α = 0,871) e todos os itens do questionário contribuíram para o aumento desse índice. Essa consistência também foi confirmada como alta no reteste (α = 0,856) e quando a amostra foi estratificada por idade e sexo. O questionário SPEED-complete também apresentou alta consistência (α = 0,88). A repetibilidade do instrumento foi alta (ICC 0,933; IC 95%: 0,899 e 0,960) e o gráfico de Bland-Altman revelou boa concordância entre as medidas. Conclusão: O Standardized Patient Evaluation of Eye Dryness in Portuguese (SPEED-vP) apresentou boas propriedades psicométricas para a população portuguesa. Portanto, a versão traduzida do questionário SPEED-vP pode ser usada para mensurar quantitativamente a presença de sintomas de olho seco na população portuguesa.
- Aerosol absorption measurements at the ALOMAR subarctic stationPublication . Montilla, Elena; Rodríguez, Edith; Mogo, Sandra; Cachorro, Victoria; Rodrigo, Rúben; de Frutos, Ángel MThe global study of atmospheric aerosol is one of the key factors in regards to climate change and those effects. Over the last 4 years a strong research work on aerosols properties characterization have been carried out into the Atmospheric Optics Group of the University of Valladolid (GOA-UVa) in Spain. We present the results about aerosol absorption coefficient measurements with two different techniques: the “integrating sphere photometer” and the particle soot absorption photometer (PSAP, Radiance Research). This data was acquired into the summer campaign 2008, made at north of Norway, like a result of the participation in-situ of GOA in the POLARCAT project, lead by the Norwegian Institute for Air Research, and included in the Fourth International Polar Year. Both methods are filter based and provide measurements that could be combined with optical column measurements for a better characterization of local aerosol. It contributes especially to the investigation of pollution events and to establishment the effects of the population over any local aerosol climatology. Based on this research background and the affordable and reliable instrumentation described in this work, the research can continue in Colombia in close collaborations with Spanish research groups.
- An integrating sphere spectral system to measure continuous spectra of aerosol absorption coefficientPublication . Montilla, E.; Mogo, Sandra; Cachorro, Victoria; De Frutos, Ángel MAn integrating sphere spectral system has been developed that allows the measurement of continuous spectra of light absorption coefficients, saðlÞ of atmospheric aerosols. This system is based on the filter attenuation method covering the spectral wavelength range 320–800 nm with a variable spectral resolution. The sample filters had to be diluted in chloroform previous to the light attenuation measurements and hence the system cannot measure continuously but only on the basis of daily sampling. The system was calibrated using known amounts of absorbing and non-absorbing industrial substances at relevant atmospheric absorption levels. The resulting values of sa ðlÞ were compared with those delivered by a commercial photometer (particle soot absorption photometer) in the laboratory and also with field measurements, with a maximum discrepancy of 12.5% for atmospherically relevant values. The measurement uncertainty of the integrating sphere system is about 10% maximum. The importance of obtaining continuous spectral data is the possibility to determine the Ångström absorption exponent, aa , in different spectral ranges, including the UV. This exponent can then be used to help in obtaining the aerosol composition information.
- Análise de Superfícies com Feixes de Iões de MEVPublication . Carvalho, José Pacheco De; Pacheco, Cláudia Ribeiro; Reis, AntónioExistem várias técnicas complementares de análise de superficies de materiais. As técnicas nucleares, com feixes de iões de baixa energia de MeV, dão valores absolutos de concentrações de isótopos e elementos para vários microns junto da superfície. As principais aplicações têm sido em áreas tais como científicas, tecnológicas, industriais, artes, arqueologia e medicina. A detecção de isótopos com altas sensibilidades é possível através de recções nucleares. É usado o método de análise em energia para reacções ião-ião. Para uma energia de bombardeamento adequada, é gravado um espectro em energia de iões de eventos da reacção que ocorrem a várias profundidades na amostra. Tais espectros são simulados em computador e comparados com os dados, dando informação de composição e perfis de concentração da amostra. A difusão elástica é um caso particular e importante de reacções nucleares. Tem sido desenvolvido um programa computacional neste contexto, principalmente para amostras planas. O caso de amostras não planas aparece como uma extensão. O perfil de profundidade de núcleos leves, e.g. carbono-12 (12C), é feito com a reacção 12C(d,p0)13C numa amostra espessa e plana de pureza extremamente elevada de grafite pirolítica. Estão disponíveis detalhes experimentais. As simulações utilizam dados nucleares publicados, nomeadamente para seccão eficaz diferencial e stopping power. É obtido um muito bom ajuste computacional aos dados espectrais para uma elevada profundidade de X1=15 μm. A análise por reacções nucleares mostrou ser um instrumento altamente poderoso para análise não-destrutiva de superfícies de materiais.
- Applications of low energy mev ion beams and computer simulation to surface analysis of materialsPublication . Carvalho, José Pacheco de; Pacheco, Cláudia Ribeiro; Reis, AntónioThis work is about surface analysis by nuclear techniques, which are essentially non-destructive, and computer simulation. The energy analysis method for nuclear reaction analysis is used. Elastic scattering is a particular and important case. Energy spectra are computer simulated and compared to experimental data, giving target composition and concentration profile information. The simulations use, mainly, target parameterization and available nuclear data. The method is successfully applied to determination of a uniform concentration profile of 18O from the (p,α) reaction in a thick oxide target. Uniform concentration profiles of 12C are obtained from the (d,p) reaction for a thick target. Uniform concentration profiles of 16O are also obtained from (d,p) and (d,α) reactions along large depths. Elastic scattering is used for depth profiling of Al and O in a thick target.
- Asynchronous Sequential Symbol Synchronizers based on Pulse Comparison by Hybrid Transitions at Quarter Bit RatePublication . Reis, António; Rocha, José Ferreira da; Gameiro, Atilio; Carvalho, José Pacheco deThis work studies the asynchronous sequential symbol synchronizers based on pulse comparison by hybrid (both and positive) transitions at quarter bit rate. Their performance will be compared with the standard reference asynchronous symbol synchronizers based on pulse comparison by both transitions at bit rate. For the reference and proposed variants, we consider two versions which are the manual (m) and the automatic (a). The objective is to study the four synchronizers and evaluate their output jitter UIRMS (Unit Interval Root Mean Square) versus input SNR (Signal Noise Ratio).