3,472 research outputs found

    The meaning of mainland Portugal beaches and dunes' psammophilic plant communities: a contribution to tourism management and nature conservation

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    Due to their position of interface between the sea and land, the flora and vegetation of coastal beaches and dunes, occupy ecologically extreme, sensitive, unique and valuable habitats. The occurrence of a large number of endemic taxa and specific plant associations endowed with key ecological services and adapted to a stressful and harsh environmental gradient, gives them a high interest for nature conservation and an important role in sustainable territorial planning. However, such ecosystems are vulnerable to the disruption caused by several anthropogenic sources. Among other global threat factors, the inevitable sea rise caused by climate change and, at a local scale, the non-negligible implications of trampling caused by disorderly coastal touristic exploitation, growing construction pressure in the littoral, and a seasonal population boom in late spring and in summer, plus all derivate forms of pollution, are threat factors to their integrity. Therefore, a correct planning of the touristic economic activities requires the understanding of the vegetation composition and spatial distribution patterns, intrinsically determined by their biogeographic context in the Euro-Siberian or Mediterranean Regions. This comprehensive work, based on a broad phytogeographic study, brings together disperse information on plant communities of the Portuguese sandy coasts (beaches and dunes), by analysing floristic compositions, chorology and ecological characteristics, and matching them with the “Nature 2000” network habitats. Resilience and vulnerability are also studied. In a nature conservation perspective, a positive balance (and a sustainable co-existence) between the preservation of natural values and human development in the Portuguese coast, will benefit with the integration of this knowledge in coastal planning and management activitie

    A microcontroller based voltage space vector modulator suitable for induction motor drives

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    Pulse width modulation techniques (PWM), introduced two decades ago, are the most used methods to control the voltage and frequency supplied to electrical AC machines. This paper describes a pulse width modulator based on the voltage space vectors technique that accepts voltage demands in dq coordinates and generates three phase PWM waveforms to drive a variable frequency voltage source inverter. A scheme based on a high performance 16 bit standard microcontroller with minimum of additional hardware is used, which allows a flexible and economical solution. The output frequency of the modulator can be varied in a large range and with a good resolution. Experimental data obtained from an induction motor drive will be presented.(undefined

    Built Heritage Research and History of Architecture: Light and Acoustic in the Cistercian Monastic Church of S. Bento de Cástris (Portugal)

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    The research on the Cistercian legacy in Portugal is an innovative multidisciplinary study. Consequently, the results achieved in this research have many different approaches: the former monasteries and their architecture are the main subjects concerning morphology, architectonic rehabilitation but also acoustics, thermal comfort, or natural light. This research, carried out at the Department of Civil Engineering and Architecture of the University of Beira Interior (DECA-UBI), was developed in connection with two other research centres - Lab2PT (Landscape, Heritage and Territory Laboratory) and CIDEHUS (Interdisciplinary Centre for History, Culture and Societies). In 2015, the curriculum of the Integrated Master Degree in Architecture of the University of Beira Interior underwent revision. Consequently, it was needed to allocate more time to the teaching of History of Architecture and the requirement to assign specific syllabus to the Portuguese History of Architecture, which is emphasized by the specific and multidisciplinary research performed linking with other sciences of engineering. The natural light in the Cistercian churches is closely linked not only with the liturgical requirements at the officium but also with the canonical hours based on the "ora et labora" dictated by the Rule of St. Benedict. The Cistercian Monastery of São Bento de Cástris (13th-19th centuries), in Évora, Portugal, includes a church, at the south-eastern corner. This church presents an unusual space setting with two choirs which seems to favour different positions for coral groups supporting liturgical and musical expression activities within the research scope of a Research Project. As the light in the Cistercian Monasteries, mainly, in their churches, is mostly related to the fulfilment of liturgical needs, this paper analyses the relationship between daylight conditions within the monastic choirs located within the monastic church. The chant was a very important way of oration and thus of the liturgy. This was the ORFEUS Project – “The Tridentine Reform and music in the cloistral silence: The Monastery of S. Bento de Cástris” which was based on a multidisciplinary approach around the Tridentine Reform with reflexes in the musical Cistercian feminine matrix between the 16th and 18th centuries on Cistercian Monasteries. This paper describes the objectives and methodology applied to the case study thus linking Built Heritage Research and History of Architecture, i.e., Research and Education.info:eu-repo/semantics/publishedVersio

    Essence of Daylight in the Cistercian Monastic Church of S. Bento de Cástris, Évora, Portugal

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    Natural light in the Cistercian churches is closely linked not only with the liturgical requirements at the “officium” but also with the canonical hours based on the "ora et labora" dictated by the Rule of St. Benedict. The Cistercian architecture, in its beginnings (12th century forward) is characterized by austerity, simplicity and the play of light and shadow that gives value to the monastic architectural space itself, making it perfect for a contemplative experience. In the Cistercian Monastery the church is the central piece of the monastic building. Nave, transept and apse are the main architectural components to which is added the choir. This paper contextualizes the importance and close connections of natural light, within the Cistercian Monasteries architecture. Thus the essence of daylight is analyzed within the Church of the Monastery of S. Bento de Cástris, in Évora, Portugal. This former Monastery (13th - 19th centuries) includes the church, at the southeastern corner which has not only a high choir, but also a low lateral choir (within the presbytery). Its unchanged exterior walls are made of solid masonry. Although the function of the walls is primarily structural, the windows allow the daylight to penetrate the space of the church. The church has two external façades facing northeast and southeast. The combined orientation effect of the church’s main axis and the sun trajectory determines how the sunlight reaches the interior of this architectural structure. This study presents the qualitative and quantitative analysis of the luminous environment in the church of S. Bento de Cástris, being the first based on the authors’ perception of the effect of the daylight within the different areas of the enclosed space. The appreciation of the spatial experiences was supported by quantitative daylight simulations that were conducted in selected areas within the space. With this paper is intended to contribute to the debate about the specificity of daylight, in the context of Cistercian architecture.info:eu-repo/semantics/publishedVersio

    Qualidade de energia eléctrica

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    O número de conversores electrónicos de potência utilizados, sobretudo na indústria, mas também pelos consumidores em geral, não pára de aumentar. Em resultado disso é possível observar uma crescente deterioração das formas de onda de corrente e tensão dos sistemas de potência. Os prejuízos económicos resultantes deste e de outros problemas associados aos sistemas eléctricos são muito elevados, e por isso a questão da qualidade da energia eléctrica entregue aos consumidores finais é hoje, mais do que nunca, objecto de grande preocupação. Neste artigo será abordado o tema da análise e solução dos problemas relacionados com a qualidade da energia eléctrica, na sua vertente mais clássica – perturbações causadas por sobretensões e subtensões, interrupções de serviço, etc. – e, principalmente, no que diz respeito aos problemas causados pelos harmónicos, decorrentes da utilização de cargas não lineares.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ESE/41170/2001

    Active filters with control based on the p-q theory

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    Due the intensive use of power converters and other non-linear loads in industry and by consumers in general, it can be observed an increasing deterioration of the power systems voltage and current waveforms. The presence of harmonics in the power lines results in greater power losses in distribution, interference problems in communication systems and, sometimes, in operation failures of electronic equipments, which are more and more sensitive since they include microelectronic control systems, which work with very low energy levels. Because of these problems, the issue of the power quality delivered to the end consumers is, more than ever, an object of great concern. International standards concerning electrical power quality (IEEE-519, IEC 61000, EN 50160, among others) impose that electrical equipments and facilities should not produce harmonic contents greater than specified values, and also specify distortion limits to the supply voltage. Meanwhile, it is mandatory to solve the harmonic problems caused by those equipments already installed. Passive filters have been used as a solution to solve harmonic current problems, but they present several disadvantages, namely: they only filter the frequencies they were previously tuned for; their operation cannot be limited to a certain load; resonances can occur because of the interaction between the passive filters and other loads, with unpredictable results. To cope with these disadvantages, recent efforts have been concentrated in the development of active filters. This paper focuses on active filters with control based on the p-q Theory

    A kalman filter for validate points and areas of constant depth in the acquisition of the profiles surfaces

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    This paper presents multisensor fusion techniques for the acquisition of the profile of surfaces with minimum error using low cost ultrasonic sensors. These surfaces are composed by areas with different depths, corners and specular surfaces. To minimize the constraints of sonar sensors, it was developed dedicated software and hardware, as well as an empirical model was obtained from real data. This model is based in two proposed concepts: Points of Constant Depth (PCD) and Areas of Constant Depth (ACD). Having this sonar model in mind, four sensor fusion techniques are used separately to validate the PCDs and decide the ACDs: average and variance, a simplified kalman filter and heuristic method based in rules. In this work a PUMA 560 manipulator was equipped with a CCD video camera and four ultrasonic sensors on the wrist, to acquire data for internally representation of the geometry of the part’s surface, exploiting the mobility of the robot. The CCD camera defines the working area while the ultrasonic sensors enable the acquisition of the surface profile

    Acquisition the profile of surfaces with complementary sensor fusion techniques

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    This paper presents complementary sensor fusion techniques for the acquisition of the profile of surfaces with minimum error using low cost sensors ultrasonic sensors. These surfaces are composed by areas with different depths, corners and specular surfaces. To minimize the constraints of sonar sensors, it was developed dedicated software and hardware, as well as an empirical model was obtained from real data. This model is based in two proposed concepts: Points of Constant Depth (PCD) and Areas of Constant Depth (ACD). Having this sonar model in mind, four sensor fusion techniques are used separately to validate the PCDs and decide the ACDs: average and variance, fuzzy controller and heuristic method based in rules. In this work a PUMA 560 manipulator was equipped with a CCD video camera on the shoulder and four ultrasonic sensors on the wrist, to acquire data to model the geometry of the part’s surface, exploiting the mobility of the robot. The CCD camera view defines the working area, while the ultrasonic sensors enable the acquisition of the surface profile. For the acquisition of the profile of surfaces with a minimum error different and complementary sensor fusion techniques are implemented and applied separately, namely the average and variance, kalman filter, fuzzy controller and heuristic method based in rules

    Machine learning-enhanced T cell neoepitope discovery for immunotherapy design

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    Immune responses mediated by T cells are aimed at specific peptides, designated T cell epitopes, that are recognized when bound to human leukocyte antigen (HLA) molecules. The HLA genes are remarkably polymorphic in the human population allowing a broad and fine-tuned capacity to bind a wide array of peptide sequences. Polymorphisms might generate neoepitopes by impacting the HLA-peptide interaction and potentially alter the level and type of generated T cell responses. Multiple algorithms and tools based on machine learning (ML) have been implemented and are able to predict HLA-peptide binding affinity with considerable accuracy. Challenges in this field include the availability of adequate epitope datasets for training and benchmarking and the development of fully integrated pipelines going from next-generation sequencing to neoepitope prediction and quality analysis metrics. Effectively predicting neoepitopes from in silico data is a demanding task that has been facilitated by ML and will be of great value for the future of personalized immunotherapies against cancer and other diseases.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research received funding from Fundação para a Ciência e a Tecnologia (FCT) contract IF/00474/2014; PhD scholarship SFRH/BD/132797/2017.info:eu-repo/semantics/publishedVersio
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