University of Beira Interior
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Metodologia de previsão da auto-compactabilidade de betões na fase argamassa
No full textO trabalho apresenta um estudo experimental conduzido como base metodológica para a previsão da composição de um betão auto-compactável a partir da manipulação racional de alguns parâmetros definidos na fase argamassa. Com esse objectivo uma série de argamassas foram produzidas em laboratório com propriedades reológicas semelhantes, e adequadas para a obtenção de betões auto-compactáveis, mensuradas através dos ensaios de espalhamento (slump flow) e de fluidez (v funnel).
Os teores de água e de superplastificante foram determinados experimentalmente para cada argamassa. Diferentes percentagens de materiais finos foram incorporadas como substituto parcial do cimento, constituindo misturas binárias. Cada mistura resulta da combinação de um dos dois tipos de cimento utilizados (CEM II/B-L32,5N e CEM I 42,5R) com uma das três adições minerais seleccionadas: fíler calcário, fíler granítico e cinza volante. Cada mistura binária de materiais finos foi combinada em cinco diferentes proporções em volume com o agregado fino (Vp/Vs). As argamassas foram ensaiadas à compressão na idade de 28 dias e os resultados obtidos foram relacionados com a razão água/cimento, a percentagem de materiais de substituição e o parâmetro Vp/Vs. As análises revelaram a pertinência dos parâmetros propostos para a previsão e obtenção simultânea, na fase argamassa, da auto-compactabilidade e da resistência à compressão requeridas ao betão auto-compactável.info:eu-repo/semantics/publishedVersio
Perspetivas sobre o género na história da antropologia cultural
No full textO presente texto aborda, numa ótica histórica, o estatuto das mulheres na antropologia, por um lado como objetos de estudo e, por outro, como profissionais nesse ramo científico.
Nas ciências sociais, durante muitas décadas, os estudos focaram-se na vida dos homens e na perspetiva masculina – interpretadas como representativas da sociedade no seu todo. As mulheres, quando recebiam atenção na antropologia, muitas vezes eram apresentadas como seres distintos da norma. Contudo, nem sempre foi assim: em vários estudos do período clássico da antropologia o mundo e as atividades das mulheres têm um lugar central. Na última parte do texto discute-se a vida e o trabalho de algumas antropólogas da primeira metade do século XX e os efeitos aparentes do ser mulher na sua carreira académica.
This text discusses, in a historical perspective, the status of women in anthropology, on the one hand as objects of study and, on the other hand, as professionals in this discipline.
In the social sciences, for many decades, attention was directed to the life of men and the male perspective – interpreted as being representative of the society at large. When women received attention in anthropology, they were often presented as being intrinsically different from the norm. However, in some studies of the classical period of anthropology, the world and the activities of women had a central place. In the last part of the text, life and work of some female anthropologists of the first half of the twentieth century are discussed, as well as the effect their female condition may have had on their academic career.info:eu-repo/semantics/publishedVersio
An Input in the Asian Wasp Nest (AWN) Study
No full textThe Asian Wasp Nest (AWN) is an impressive and robust natural construction built by an insect. The building process occurs during spring and summer. This type of nest is not reused. The scale size between the Asian wasp and the AWN is substantial. In Portugal, we can find AWN on trees, roofs, balconies, chimneys, and other possibilities. When the AWN is built on trees, the tree's branches work as support. The complexity of this natural construction in terms of shape motivated this research work. Therefore, an AWN sample was used in order to obtain some information concerning this technical aspect. In this context, X-ray tests were performed to give guidance about the internal structure of the AWN without damaging it. The obtained experimental results show the richness of this type of construction. Understating the AWN may guide new building processes, different structural shapes, alternative natural building materials, and passive building technics, among other constructive fields.This work was partially supported by the FCT (Portuguese Foundation for Science and Technology) through the projects UIDB/04082/2020 (CMADE),
UIDB/CVT/00772/2020 (CECAV) and LA/P/0059/2020 (AL4AnimalS). The collaboration of the
Veterinary Hospital of UTAD was also priceless.info:eu-repo/semantics/publishedVersio
Methodology for the mix design of self-compacting concrete using different mineral additions in binary blends of powders
No full textInteraction between the coarse aggregates and the mortar phase of self-compacting concrete (SCC) was evaluated in a two phase program. In the first phase, 74 mortars suitable for SCC were produced, combining different volumetric ratios between powders and fine aggregates and different binary blends of powders. In the second phase, 60 concretes were produced with different volumetric ratios between the mortar phase and the coarse aggregates, and their fresh and hardened properties were evaluated. Based on this study, correlations between mix design parameters, fresh and hardened properties were obtained and a methodology was proposed for the mix design of SCC.info:eu-repo/semantics/publishedVersio
Deteção molecular de clostridia, produtores de neurotoxinas botulínicas do tipo A, B, E e F por PCR
No full textO presente relatório de estágio está integrado no 2º ano do Mestrado em Biotecnologia,
da Universidade da Beira Interior. Este decorreu durante oito meses no departamento
de Biologia Molecular da empresa multinacional ALS Life Sciences Portugal, S.A.,
sediada em Tondela. O principal objetivo foi o desenvolvimento e validação de um
método de deteção molecular de clostridia, produtores de neurotoxinas botulínicas do
tipo A, B, E e F por PCR em tempo real.
Clostridium botulinum é uma bactéria anaeróbia que produz neurotoxinas altamente
potentes e endósporos resistentes, daí ser uma preocupação mundial a nível da
segurança alimentar. Após a sua ingestão, a toxina liga-se aos terminais nervosos
colinérgicos onde, devido à sua atividade como endopeptídase, cliva as proteínas
responsáveis pela libertação de acetilcolina para a fenda sináptica. Devido a esta ação, a
transmissão nervosa fica comprometida. Assim, é crucial haver um diagnóstico rápido
com base em metodologias sensíveis e específicas da análise de DNA, para detetar esta
bactéria em alimentos.
Neste trabalho pretendeu-se, através da aplicação da técnica de PCR em tempo real,
fazer a deteção molecular de clostridia produtores de neurotoxinas botulínicas tipo A,
B, E e F. Este método apresenta uma evolução comparativamente à técnica de PCR
convencional devido a ser mais rápido e sensível.
Foram realizados testes para a determinação do limite de deteção, análise de
especificidade e contaminação artificial de amostras reais. Para isso utilizaram-se 11
bactérias diferentes e 5 tipos de matrizes alimentares, sugeridas na norma ISO/TS
17919:2013. Os resultados demostraram especificidade de primers e sonda e um limite
de deteção de 10 cópias/µL para a toxina A, B e F e um limite de 100 cópias/µL para a
toxina E.his internship report is part of the 2nd year of the Master's degree in Biotechnology, of
the University of Beira Interior. It took place during eight months in the Molecular
Biology department of the multinational company ALS Life Sciences Portugal, S.A, in
Tondela. The main objective was the development and validation of a molecular
detection method of clostridia, producers of botulinum neurotoxins type A, B, E and F
by PCR.
Clostridium botulinum is an anaerobic bacterium that produces highly potent
neurotoxins and resistant endospores, making it a global food safety concern. After
ingestion, the toxin binds to the cholinergic nerve terminals where, due to its activity as
an endopeptidase, it cleaves the proteins responsible for the release of acetylcholine
into the synaptic cleft. Due to this action, nerve transmission is compromised. Thus, it
is crucial to have a rapid diagnosis based on sensitive and specific DNA analysis
methodologies to detect this bacterium in food.
This work aims, by applying the real-time PCR technique, to make the molecular
detection of clostridia that produce botulinum neurotoxins type A, B, E and F. This
method presents an evolution compared to the conventional PCR technique due to
being faster and more sensitive.
Specificity and artificial contamination tests of real samples were performed. For this,
11 different bacteria and 5 types of food matrices were used, as suggested in ISO/TS
17919:2013. The results showed primer and probe specificity and a detection limit of 10
copies/µL for toxin A, B and F and a limit of 100 copies/µL for toxin E
Un hormigón autocompactante eco-amigable con áridos gruesos reciclados
No full textThe potential uses of coarse recycled aggregates in the composition of SCC increases the ecological value and partly solve the issues of waste disposal sites generated by construction and demolition of structures. Thus, this paper present an experimental study of SCC properties where the normal coarse aggregates were replaced by different percentages of recycled aggregates, i.e., 0% (SCC), 10% (SCCR10), 20% (SCCR20), 30% (SCCR30) and 40% (SCCR40). The results from fresh concrete (rheological properties and self-compactability) as the hardened concrete properties (compressive strength, density and dynamic modulus of elasticity), show only minor discrepancies. From the standpoint of mechanical behaviour, the results confirm the viability to incorporate coarse recycled aggregates in the SCC demonstrating the conservative character of the currently recommended limits.Los usos potenciales de áridos gruesos reciclados en la composición del hormigón autocompactante (SCC) aumenta el valor ecológico y en parte resuelve los problemas de los sitios de disposición de residuos generados por la construcción y la demolición de las estructuras. Por lo tanto, este trabajo presenta un estudio experimental de las propiedades de SCC en el cual los áridos gruesos naturales fueron reemplazados por distintos porcentajes de áridos reciclados, es decir, 0% (SCC), el 10% (SCCR10), el 20% (SCCR20), el 30% (SCCR30) y el 40% (SCCR40). Los resultados del hormigón fresco (propiedades reológicas y la auto-compactación), como las propiedades de hormigón endurecido (resistencia a la compresión, densidad y módulo de elasticidad dinámico), muestran sólo pequeñas discrepancias. Desde el punto de vista del comportamiento mecánico, los resultados confi rman la viabilidad de incorporar áridos gruesos reciclados en los SCC demostrando el carácter conservador de los límites actualmente recomendados.info:eu-repo/semantics/publishedVersio
Identification of Gas Turbine Ground Vortex Formation Regimes
No full textIn the present paper the previous work of Barata et al.11 is extended to include eighteen engines that are being used in the present. The ground vortex flows produced by the different engines are compared and discussed for each operational condition. The results have shown that more than one mode can occur for a particular engine-velocity ratio-clearance distance combination with 1, 2 or 3 vortexes that may merge before entering the inlet engine.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Numerical simulation of an array of droplets through a crossflow
No full textThis paper describes the application of a three-dimensional computational method based on the solution of the Reynolds-averaged Navier-Stokes equations and a SSF (stochastic separated flow) model to the problem of an array of droplets through a crossflow. The calculation method is first evaluated against measurements for two-phase axisymmetric jets, and then extended to the three-dimensional case. The influence of the droplet sizes on the dispersion phenomena is analyzed. The exchange of momentum and turbulence energy was shown to play a decisive role in the change of the gaseous flow velocities. The analysis of the source terms due to the droplets revealed a strong influence of the boundary layer near the injection point in the dispersion process.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Advanced statistical analysis of the collision of wall jet with a boundary layer
No full textLaser-Doppler measurements of the velocity characteristics of a ground vortex flow resulting from the collision of a wall jet with a boundary layer are analyzed using advanced statistical tools. Namely, finite mixtures of probability density functions, which determine the best fitting using a Bayesian approach based on a Markov Chain Monte Carlo (MCMC) algorithm. This approach takes into account eventual multimodality and heterogeneities in velocity field distributions. Therefore, it provides more complete information about the probability density function of multimodal velocity distributions and allows the identification of characteristic velocities in the heterogeneous data. The experiments are performed for a wall jet-to-boundary layer velocity ratio of 2, and include mean and turbulent velocity characteristics along the two normal directions contained in planes parallel to the nozzle axis. The results, which have relevance to flows encountered by VSTOL aircraft, quantify the structure of the complex ground vortex flow. The results revealed that in the collision zone the rms velocity fluctuation appears to be overestimated for the horizontal component, probably due to the measured velocity range, oscillating between positive and negative values. The results revealed that finite mixture was able to accurately reconstruct a mathematical function describing the probability distribution obtained experimentally. The results shows that U and u'rms rms provide an idea of the flow dynamics, their use is limited and an important amount of information associated with the highly curved flow complexity is lost, preventing a more accurate description of turbulent structures emerging from the collision of wall jet with a boundary layer.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Numerical Analysis of a Single Droplet Combustion of Jet-A1 and Alkanes
No full textThe demand for aviation fuel is constantly increasing and has become apprehensive due to the depletion of fossil fuels. The use of petroleum sourced fuels as an energy source in the air transportation industry consists of an unsustainable alternative. Due to this, the introduction of alternative jet fuel is required to mitigate these issues. Thus, the present work simulates single droplet combustion numerically in a drop tube furnace. In this context, jet-A1 and n-Hexadecane were investigated. Additionally, it is studied the validation of approximating the combustion of alternative jet fuel to n-hexadecane. The employed model consists of a two-way coupling approach between the fuel droplets and the carrier fluid following an Eulerian-Lagragangian schematic. The continuous phase is primarily modeled and further coupled with the fuel droplets known as the discrete phase. A combustion model is employed in order to simulate the natural phenomenon of single droplet combustion to the intended utilized fuels. The results reveal that the droplet diameter reduces as the time evolves under the representation of the d2 law enabling the computation of different combustion characteristics being affected by the fuel composition.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio