Browsing by Issue Date, starting with "2020-07"
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- Relatório Anual (2019.2020) - 2º ano da Licenciatura em Relações Comerciais China-Países LusófonosPublication . Mangas, Catarina; Milhano, Sandrina; Almeida, AuréliaRelatório que sintetiza a forma como decorreu o ano 2019/2020, perspetivando-se como um instrumento de reflexão e análise sobre as práticas, no sentido de apontar direções para a melhoria da qualidade do processo de ensino-aprendizagem e do consequente aumento de competências por parte dos estudantes.
- All-digital reconfigurable STDCC radar baseband implementation in FPGAPublication . Duarte, Luís; Ribeiro, Carlos; Alves, Luís N.; Caldeirinha, Rafael F. S.This paper reports the architecture of an all-digital Swept Time-Delay Cross-Correlator (STDCC) baseband. Until recently, the sliding correlator technique has been mainly em-ployed for sounding the radio propagation channel. However, recent benchmarks have shown promising results in target detection context when compared to commercially available solutions. STDCC takes advantage of the sliding correlation properties of Pseudo-Noise (PN) sequences. Therefore, this paper presents the baseband generation for this new radar technique with on-the-fly sequence tuning using a Field-Programmable Gate Array (FPGA). The reconfigurable STDCC radar baseband generates both PN sequences digitally and requires a low-cost ADC to acquire the time dilated result. At the end, the proposed architecture is evaluated regarding resource usage efficiency and then the radar performance will be discussed in terms of the all-digital PN sequence spectrum and the real-time slide correlation. Our analysis confirmed a strong correlation between both sequence length and sampling frequency with radar detectable distance.
- Forecasting Heating and Cooling Energy Demand in an Office Building using Machine Learning MethodsPublication . Godinho, Xavier; Bernardo, Hermano; Oliveira, Filipe Tadeu; Sousa, JoãoForecasting heating and cooling energy demand in buildings plays a critical role in supporting building management and operation. Thus, analysing the energy consumption pattern of a building could help in the design of potential energy savings and also in operation fault detection, while contributing to provide proper indoor environmental conditions to the building's occupants.This paper aims at presenting the main results of a study consisting in forecasting the hourly heating and cooling demand of an office building located in Lisbon, Portugal, using machine learning models and analysing the influence of exogenous variables on those predictions. In order to forecast the heating and cooling demand of the considered building, some traditional models, such as linear and polynomial regression, were considered, as well as artificial neural networks and support vector regression, oriented to machine learning. The input parameters considered in the development of those models were the hourly heating and cooling energy historical records, the occupancy, solar gains through glazing and the outside dry-bulb temperature.The models developed were validated using the mean absolute error (MAE) and the root mean squared error (RMSE), used to compare the values obtained from machine learning models with data obtained through a building energy simulation performed on an adequately calibrated model.The proposed exploratory analysis is integrated in a research project focused on applying machine learning methodologies to support energy forecasting in buildings. Hence, the research line proposed in this article corresponds to a preliminary project task associated with feature selection/extraction and evaluation of potential use of machine learning methods.
- Analog m-CAP demodulation for VLC-based IoT systemsPublication . Rodrigues, Luís; Figueiredo, Mónica; Alves, Luís NeroFuture IoT systems will require progressively smaller sizes, cost, complexity and power consumption. This paper proposes a new architecture using a hybrid m-CAP/QAM system with the goal to provide such features to future VLC based IoT devices. The proposed system architecture uses a ceiling LED light fixture implementing an m-CAP digital modulator, connected to several IoT devices, implemented by analog demodulators. The simulated performance presents an increase on BER when compared to a digital m-CAP receiver, between 1 and 2 dB. Nevertheless, considering IoT scenarios, having low cost/size/power devices can surpass the performance penalty.
- Deep Learning-Based Point Cloud Geometry Coding: RD Control Through Implicit and Explicit QuantizationPublication . Guarda, André F. R.; Rodrigues, Nuno M. M.; Pereira, FernandoDeep learning is becoming more and more relevant for multiple multimedia processing tasks, and lately it has raised much interest in the coding arena notably for images and point clouds. While offering near state-of-the-art compression performance, current deep learning-based point cloud coding solutions have a shortcoming since they require training and storing multiple models in order to obtain different rate-distortion trade-offs. This paper proposes a solution that effectively reduces the number of deep learning models that need to be trained and stored by applying explicit quantization to the latent representation, which can be controlled at coding time, to generate varying rate-distortion tradeoffs. The proposed implicit-explicit quantization combination achieves a compression performance that is equivalent or better than the alternative, while significantly reducing the model storage memory requirements.
- Metamaterial-inspired Flat-Antenna Design for 5G Small-cell Base-Stations Operating at 3.6 GHzPublication . Reis, João R.; Fernandes, Telmo R.; Patrício Carreira Vala, Mário António; Caldeirinha, Rafael F. S.In this paper, a flat-beamsteering antenna for 5G applications is being presented. The antenna, designed to operate at 3.6 GHz (5G new radio (NR) frequency range 1 (FR1) band n78), presents a unique flat form factor which allows easy deployment and low visual impact in 5G dense scenarios. The antenna presents a multi-layer structure where a metamaterial inspired transmitarray enables the two-dimensional (2D) beamsteering, and an array of microstrip patch antennas is utilised as RF source. The use of metamaterials for beamsteering control allows for the reduction of costly and complex phase-shifter networks by using discrete capacitor diodes to control the transmission phase-shifting and subsequently, the direction of the steering. According to simulations, the proposed antenna presents 13.9 dBi of gain, 100 MHz of bandwidth with a maximum steering range of ±20 degrees, achievable in both elevation and azimuth planes, independently.
- Geriatric Assessment of the Portuguese Population Aged 65 and Over Living in the Community: The PEN-3S StudyPublication . Madeira, Teresa; Peixoto-Plácido, Catarina; Sousa Santos, Nuno; Santos, Osvaldo; Alarcão, Violeta; Nicola, Paulo Jorge; Lopes, Carla; Clara, João GorjãoIntroduction: As populations live longer, they also aim to live better. A crucial step for this is to improve the understanding about older adults' physical and psychological health. Therefore, the aim of the present study was to characterise the Portuguese population over-65 regarding nutritional status, cognitive function, functional status, symptoms of depression, and loneliness, by sex and age groups. Material and Methods: Cross-sectional study including a nationally representative sample of community-dwelling adults aged 65 and over. Trained interviewers collected data face-to-face on demographic and socioeconomic characteristics, health status, nutritional status, cognitive function, functional status for activities of daily living, symptoms of depression, and loneliness feelings. Complex sample procedures were used in the statistical analysis. Results: Overall, 1120 community-dwellers (49.0% women, 21.3% aged ≥ 85) participated in the study. The estimated prevalence of risk of malnutrition was 16.4% (95% confidence interval: 13.3 - 19.9), while 17.7% (95% confidence interval: 12.8 - 23.9) were cognitively impaired, and 28.5% (95% confidence interval: 23.7 - 33.8) presented limitations to perform daily living activities. Moreover, 23.5% (95% confidence interval: 19.7 - 27.7) presented symptoms of depression and 13.6% (95% confidence interval: 10.6 - 17.1) reported loneliness feelings. These conditions were more prevalent among women, and generally more frequent in the oldest individuals (≥ 85). Discussion: Risk of malnutrition, cognitive impairment, functional limitations, depression and loneliness were moderately frequent, which may justify screening and preventive actions at a community level. Conclusion: This study contributed to a national characterisation of the health of older adults, that may inform policies and interventions targeted at the needs of the Portuguese aging population.
- 3D Indoor Radio Coverage for 5G Planning: a Framework of Combining BIM with Ray-tracingPublication . Louro, João; Fernandes, Telmo Rui; Rodrigues, Hugo; Caldeirinha, Rafael F. S.This paper presents a framework to predict indoor radio wave coverage in buildings. Such method includes the capability to import BIM (Building Information Modelling) files that contain structured physical geometry and dimension data, including the material types that are of uttermost importance in evaluating their dielectric properties. Appropriated extraction of physical and dielectric attributes of the building elements was used as input to a 3D radio wave propagation ray-tracing developed in MatLab that allows the prediction of the received radio signal level at any location within the computational volume. Results are presented for line-of-sight contributions and first and second order reflections. Despite the generic nature of the proposed framework, prediction results are presented at 3.6 GHz, envisaging emerging 5G indoor radio coverage.
- Low-Resolution Retinal Image Vessel SegmentationPublication . Zengin, Hasan; Camara, José; Coelho, Paulo; Rodrigues, João M. F.; Cunha, AntónioSegmentation process serves to aid the pathology diagnosing process since segmentation filters the interference from other anatomical structures and helps focus on the posterior segment structures of the eye, highlighting a set of signals that will serve for diagnosis of various retinal pathologies. Automatic retinal vessel segmentation can lead to a more accurate diagnosis. This paper presents a framework for automatic vessel segmentation of lower-resolution retinal images taken with a smartphone equipped with D-EYE lens. The framework is evaluated and the attained results were presented. A dataset was assembled and annotated of train models for automatic localisation retinal areas and for vessel segmentation. For the framework, two CNN based models were successfully trained, a Faster R-CNN that achieved a 96% correct detected of all regions with an MAE of 39 pixels, and a U-Net that achieved a DICE of 0.7547.
- Da Reflexão à InvestigaçãoPublication . Gomes, Ana Beatriz Bernardino Barbeiro; Oliveira, Luís Miguel Gonçalves deO presente relatório surgiu no âmbito do Mestrado em Educação Pré-Escolar, realizado na Escola Superior de Educação e Ciências Sociais do Politécnico de Leiria. Tem como intenção, essencialmente, tornar visíveis as aprendizagens mais significativas vivenciadas nos diversos contextos da Prática de Ensino Supervisionada. Numa primeira parte, designada de dimensão reflexiva, foi contemplada a partilha de experiências em contexto de creche e de jardim de infância I e II. Considerou-se indispensável iniciar com uma reflexão sobre a criança, o educador e o brincar na infância, o contributo dos tempos, espaços e materiais no desenvolvimento e aprendizagem da criança, o percurso realizado entre a observação e a avaliação e, por último, a relação creche-criança-família. Foram explorados tópicos sobre o brincar com a oralidade e com a escrita e, por fim, o percurso realizado entre a observação e a avaliação, nos dois contextos de jardim de infância. Para finalizar, revisitámos alguma literatura sobre a Abordagem de Projeto em contextos de Educação de Infância, como também apresentámos, em jeito de partilha e reflexão, os momentos vivenciados no decorrer do projeto. Procurámos ainda evidenciar as fases que o contemplaram e as aprendizagens que emergiram com a sua implementação. Com o início das práticas, percebemos que é fundamental que todos os educadores tenham conhecimentos práticos e teóricos sobre os fundamentos e os princípios que sustentam a pedagogia da primeira infância. A vivência diária com crianças no contexto de creche, possibilitou a (re)significação da conceção da criança. Hoje, olhamo-la como um ser competente. A criança em creche participa ativamente no seu processo de desenvolvimento e aprendizagem e, por isso, tem agência neste percurso. Aprende, descobre e desafia-se, diariamente, de forma autónoma, em interação e relação com o outro. Vivenciar dois contextos de jardim de infância, ajudou-nos a compreender que a Educação Pré-escolar não é uma preparação para a escolaridade obrigatória. Mais importante do que proporcionar o contacto com letras e números, os educadores devem privilegiar, acima de tudo, a vinculação com cada criança, a sua felicidade e o seu bem-estar. A segunda parte, designada dimensão investigativa, diz respeito a um estudo desenvolvido no contexto de jardim de infância II, no 3.º semestre do mestrado. Com este ensaio investigativo foi nossa intenção conhecer com maior profundidade a avaliação na Educação Pré- Escolar, nomeadamente a implementação de uma avaliação alternativa e autêntica, dando enfoque ao papel do educador, da criança e da família neste processo de partilha. Procurou-se desconstruir o conceito de avaliação, identificar e conhecer diferentes instrumentos de avaliação e perceber como se pode construir e implementar um portefólio, em contexto de jardim de infância. Ao analisar os dados, percebemos que a avaliação que se preconiza na teoria de referência, não corresponde à que se praticou nos contextos que conhecemos. Constatou-se ainda que, quando as crianças se envolvem, verdadeiramente, no seu processo de desenvolvimento e aprendizagem, nomeadamente na construção de um recurso de avaliação, são mais felizes, autoconfiantes, conscientes, interessadas, motivadas, questionadoras e reflexivas. Também se percebeu que um portefólio deve refletir a evolução da criança em todas as dimensões, de forma sistemática, partilhada e autêntica.