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  • Light field HEVC-based image coding using locally linear embedding and self-similarity compensated prediction
    Publication . Monteiro, Ricardo; Lucas, Luis; Conti, Caroline; Nunes, Paulo; M. M. Rodrigues, Nuno; Faria, Sergio; Pagliari, Carla; Silva, Eduardo da; Soares, Luis
    Light field imaging is a promising new technology that allows the user not only to change the focus and perspective after taking a picture, as well as to generate 3D content, among other applications. However, light field images are characterized by large amounts of data and there is a lack of coding tools to efficiently encode this type of content. Therefore, this paper proposes the addition of two new prediction tools to the HEVC framework, to improve its coding efficiency. The first tool is based on the local linear embedding-based prediction and the second one is based on the self-similarity compensated prediction. Experimental results show improvements over JPEG and HEVC in terms of average bitrate savings of 71.44% and 31.87%, and average PSNR gains of 4.73dB and 0.89dB, respectively.
    2016-07Conference paper Restricted access Show more
  • DLL architecture for OFDM based VLC transceivers in FPGA
    Publication . Duarte, Luis; Rodrigues, Luis; Alves, Luis N.; Ribeiro, Carlos; Figueiredo, Mónica
    This paper addresses the problem of achieving high bandwidth in a DLL design for OFDM based VLC broadcast systems. It describes the implementation of efficient Data Link Layer (DLL) and Forward Error Correction (FEC) modules in a Xilinx FPGA. The proposed DLL aims at furnishing the adequate means to fragment and route both high data-rate (HDR) and moderate data-rate (MDR) service requests while maintaining a continuous transmission flow. The FEC modules aims at providing sufficient error correction capabilities with reasonable computation overheads. Another goal was to develop these modules under a globally asynchronous locally synchronous paradigm, ensuring high modularity and performance.
    2016-07Conference paper Restricted access Show more
  • Obstacle detection and avoidance module for the blind
    Publication . Costa, Paulo; Fernandes, Hugo; Barroso, João; Paredes, Hugo; Hadjileontiadis, Leontios J.; Costa
    Assistive technology enables people to achieve independence when performing daily tasks and it enhances their overall quality of life. Visual information is the basis for most navigational tasks, so visually impaired individuals are at disadvantage due to the lack of sufficient information about their surrounding environment. With recent advances in inclusive technology it is possible to extend the support given to people with visual disabilities in terms of their mobility. In this context we present and describe a wearable system (Blavigator project), whose global objective is to assist visually impaired people in their navigation on indoor and outdoor environments. This paper is focused mainly on the Computer Vision module of the Blavigator prototype. We propose an object collision detection algorithm based on stereo vision. The proposed algorithm uses Peano-Hilbert Ensemble Empirical Mode Decomposition (PH-EEMD) for disparity image processing and a two layer disparity image segmentation to detect nearby objects. Using the adaptive ensemble empirical mode decomposition (EEMD) image analysis real time is not achieved, with PH-EEMD results on a fast implementation suitable for real time applications.
    2016-07Conference paper Restricted access Show more
  • Single carrier optical FDM in visible light communication
    Publication . Saied, Osama; Ghassemlooy, Zabih; Kizilirmak, Refik Caglar; Dai, Xuewu; Ribeiro, Carlos; Zhang, Min.; Rajbhandari, Sujan
    Light emitting diodes (LEDs) used in visible light communications (VLC) have a limited optical power-current linear range, which could be a problem in multi-level and multicarrier frequency modulation schemes. Orthogonal frequency division multiplexing (OFDM) as a popular scheme in VLC suffers from nonlinear distortion due to the high peak to average power ratio (PAPR). In this paper, we present a novel single carrier optical frequency division multiplexing signaling scheme for VLC, where the symmetrical characteristics of single carrier frequency division multiple access is investigated in order to reduce PAPR. Simulation results show that PAPR reduced by 10 dB compared to the traditional asymmetrically clipped optical OFDM. We show that the bit-error-rate performance of the proposed scheme is enhanced compared to ACO-OFDM when the limited dynamic range of digital to analog converter and LED is considered.
    2016-07Conference paper Restricted access Show more
  • A jurisprudência portuguesa dos tribunais superiores sobre exoneração do passivo restante (Breves notas sobre a admissão da exoneração e a cessão de rendimentos em particular)
    Publication . Conceição, Ana Filipa
    Desde 2004 que o Código da Insolvência e Recuperação de Empresas apresenta dois modelos insolvenciais para o tratamento da insolvência de pessoas singulares: por um lado, o modelo reeducativo, encarnado no plano de pagamentos; por outro o fresh start, consagrado com a exoneração do passivo restante. Esta última solução tem sido a opção da esmagadora maioria das pessoas singulares insolventes que, desde 2011, superam o número de processos de pessoas coletivas. Todavia, o sistema português tem sido criticado, não só pelo Memorando da Troika assinado entre o Estado Português, o BCE, a Comissão Europeia e o FMI, como pela própria doutrina e jurisprudência, pondo em evidência a necessidade de alteração do regime relativo às pessoas singulares. Aliás, tal exigência constava do referido Memorando, sem que o Governo português tenha adotado quaisquer medidas. Por outro lado, a recomendação da UE de março de 2014, relativa à recuperação e à insolvência, refere também a necessidade de redução do limite temporal de insolvências de pessoas singulares, nomeadamente no que concerne aos períodos de cessão dos rendimentos aos credores. Nesta sede, verificamos que o regime português da insolvência, que conta já com mais de uma década de vigência, continua a apresentar fragilidades a nível da aplicação das normas, especialmente em dois pontos particulares – por um lado, a interpretação dos requisitos de acesso, que foi inicialmente feita de forma muito rígida pelos tribunais de 1.ª instância, impedindo o acesso à exoneração e, por outro, a concessão dos rendimentos necessários durante o período de cessão aos credores que, normalmente, desvaloriza as verdadeiras necessidades dos insolventes, dando um caráter punitivo, que o legislador não pretendeu atribuir, à insolvência. Este texto visa, pois, analisar brevemente a evolução jurisprudencial dos tribunais superiores na última década.
    2016-07Journal article Open access Show more
  • Core Sets da Classificação Internacional de Funcionalidade, Incapacidade e Saúde (CIF) para a Artrite Reumatoide segundo a perspetiva dos indivíduos
    Publication . Pereira, Andreia; Coelho, Jéssica; Silva, Margarida; Pedra, Mariana
    Introdução: A complexidade da utilização da CIF devido ao elevado número de categorias levou à necessidade de desenvolver Core Sets de forma a identificar e agrupar os principais problemas dos indivíduos para as diferentes condições de saúde. Contudo, mostra-se necessário comparar estes Core Sets iniciais com a perspetiva dos indivíduos em diferentes países, para uma melhor utilização deste instrumento na prática clínica. Objetivo: Identificar os principais problemas percecionados pelos indivíduos com AR em Portugal e verificar se estes se encontram contemplados nos comprehensive e brief Core Sets da CIF para a mesma condição. Metodologia: Esta investigação consiste num estudo qualitativo com uma amostra de conveniência com indivíduos com AR. Para a recolha de dados foram utilizadas entrevistas individuais gravadas sobre a forma de áudio, sendo o procedimento do estudo baseado no protocolo de Coenen M., (2008). Resultados: O estudo inclui 20 indivíduos com uma média de idade de 61,35 (±10,5) anos, sendo que 95% pertenciam ao género feminino e 5% ao género masculino. Das 99 categorias identificadas, 41 (42,71%) encontram-se presentes nas 96 categorias do comprehensive Core Sets da CIF e 31 (79,49%) nas 39 categorias dos brief Core Sets da CIF. Conclusões: O presente estudo conclui que embora os Core Sets da CIF para a AR sejam específicos para os indivíduos com esta condição, quando comparados com a população portuguesa, estes não apresentam vários problemas identificados por estes indivíduos. Para além disso, estes Core Sets da CIF contêm problemas que não foram relatados por esta população.
    2016-07Bachelor thesis Open access Show more
  • Insulin resistance is associated with tissue-specific regulation of HIF-1α and HIF-2α during mild chronic intermittent hypoxia
    Publication . Sacramento, J.F.; Ribeiro, M.J.; Rodrigues, T.; Guarino, Maria Pedro; Diogo, L.N.; Seiça, R.; Monteiro, E.C.; Matafome, P.; Conde, S.V.
    Chronic intermittent hypoxia (CIH) is a feature of obstructive sleep apnea (OSA). Whereas clinical stud-ies have demonstrated the association between OSA and insulin resistance, the molecular mechanismsbehind it are still unknown. Herein we investigated the effect of mild CIH on insulin sensitivity and weevaluated the changes in insulin and HIF signaling pathways that occur in CIH-induced insulin resistance.We showed that mild CIH obtained by 5/6 hypoxic (5%O2) cycles/h, 10.5 h/day during 28 and 35 daysincreased arterial blood pressure. Insulin resistance and insulinemia increased with CIH duration, beingsignificantly different after 35 days of CIH. Thirty-five days of CIH decreased insulin receptor expressionand phosphorylation in skeletal muscle and adipose tissue, but not in the liver. Conversely, Glut2 expres-sion increased in the liver of CIH-animals. Thirty-five days of CIH up-regulated HIF-1 in the liver anddown-regulated HIF-1 and HIF-2 in skeletal muscle.We concluded that the effect of CIH on insulin sensitivity and signaling is time-dependent and isassociated with changes in HIF signaling in insulin-sensitive tissues.
    2016-07Journal article Restricted access Show more
  • SSN: Senior Social Network for Improving Quality of Life
    Publication . Marcelino, Isabel; Laza, Rosalía; Pereira, António; Pereira, António
    The world population is aging and loneliness has become one of the major issues affecting the quality of life of our senior citizens. Additionally, we have observed that social computing increases social contexts through the use of Information Communication Technology (ICT). Smartphone and tablet proliferation also empower people to interact and create and share contents, strengthening new forms of communication independent of time and space. Therefore, the senior population would have a lot to gain by using social networks to overcome their solitude. Nevertheless, the elderly are still digitally excluded due to their lack of technological skills, as well as age-related impairments. This work presents a social network tailored for the senior population where the feelings of belonging, companionship and connectivity, well-being and interaction, meaningfulness, and emotional comfort are empowered. Our contribution aims to digitally include all seniors—independent of their educational level, literacy, or technological skills—by promoting a social network that allows them to share their life experiences, strengthen communication, improve their awareness of still playing an active and useful role in society, encourage emotional comfort, improve their health condition, and provide new forms of joyful entertainment in their lives. The final evaluation indicates that all seniors were very enthusiastic about the experience.
    2016-07-01Journal article Open access Show more
  • Os deveres gerais dos gestores e a regra de decisão empresarial
    Publication . Pereira, Ana Sofia Neto; Dinis, Marisa Catarina da conceição
    Os deveres gerais dos gestores, a responsabilidade civil e a regra de decisão empresarial são o objeto principal do presente estudo. Será incontornável que a atual conjuntura económica, marcada pela recessão generalizada e pela instabilidade dos mercados, contribuiu e contribui para a perda da confiança dos agentes económicos, o que, por corolário, acaba por afetar as sociedades comerciais. Os gestores, neste “ambiente hostil”, ao assumirem o controlo, poderão na sede das suas funções revelar alguma precipitação na tomada das suas decisões, e mesmo deliberações que acabem por não cumprir os interesses da sociedade, dado os constrangimentos estruturais evidenciados. Assim, pretendemos analisar a problemática inerente às questões ligadas à responsabilidade civil dos gestores bem como à determinação e à violação dos respetivos deveres gerais. Pretendemos ainda analisar os pressupostos necessários à exclusão da responsabilidade dos gestores no âmbito da aplicação do nº2, do artigo 72º do CSC. Para concretizarmos o nosso objetivo, traçámos o seguinte plano de estudos: primeiramente será apresentada a delimitação do objeto de estudo, com a exposição de um quadro de conceitos e de dogmáticas considerados primordiais para a compreensão das temáticas sob estudo. Depois de delimitados os problemas jurídicos decorrentes da aplicação do regime legal, avançaremos para a análise das questões controversas que, podemos avançar, são em elevado número. Trataremos, posteriormente, de refletir sobre as soluções avançadas pela doutrina e pela jurisprudência para dar a resolver as preditas questões. Será, neste momento, que apresentaremos a nossa reflexão crítica sobre estas temáticas. O presente estudo será concluído com a apresentação das conclusões principais.
    2016-07-04Master thesis Restricted access Show more
  • Impact of financial crisis on earnings management in listed companies of Portugal and UK
    Publication . Kacharava, Aleksandre; Lisboa, Inês Margarida Cadima
    Firm’s financial information is essential to stakeholders’ decision making. Although not always financial statements show the firm’s real image. This study examines listed firms from Portugal and UK. Firms have different purposes to manipulate earnings: some strive for influencing investors’ perception about a particular company, some try to provide better position for gaining finance from credit institutions or paying less tax to tax authorities. Usually, this behaviour is induced when firms have financial problems. Consequently, the study also aims to see the impact of financial crisis on earnings management. We try to answer question how does extent of firms’ involvement in earnings management change when the world undergoes financial crisis. Furthermore, we also compare two countries with different legal forces in terms of quality of accounting to see the main differences. We used a panel data methodology to analyse financial data from 2004 till 2014 of listed firms from Portugal and UK. Beneish (1999) model was applied to categorize manipulator and non-manipulator firms. Analysing accounting information according to Beneish’s ratios, findings suggest that financial crisis had certain impact on firms’ tendency to manipulate financial results in UK although it is not statistically significant. Moreover, besides the differences between Portugal and UK, results contradict the common view of legal systems’ quality, as UK firms tend to apply more accounting techniques for manipulation than the Portuguese ones. Our main results also confirm that some UK firms manipulate ratios of receivables’ days, asset quality index, depreciation index, leverage, sales and general administrative expenses whereas Portuguese firms manipulate only receivables’ days. Finally, we also find that the main reason to manipulate results is not to influence the cost of obtained funds neither to minimize tax burden since net profit does not explain the ratios used in the Beneish model. Results suggest that the main concern to listed firms manipulate results is to influence financial investors perception.
    2016-07-04Master thesis Open access Show more