37 resultados para source encoder identification

em Repositório Científico do Instituto Politécnico de Lisboa - Portugal


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No início da década de 90, as empresas começaram a sentir a necessidade de melhorar o acesso à informação das suas actividades para auxiliar na tomada de decisões. Desta forma, no mundo da informática, emergiu o sector Business Intelligence (BI) composto inicialmente por data warehousing e ferramentas de geração de relatórios. Ao longo dos anos o conceito de BI evoluiu de acordo com as necessidades empresariais, tornando a análise das actividades e do desempenho das organizações em aspectos críticos na gestão das mesmas. A área de BI abrange diversos sectores, sendo o de geração de relatórios e o de análise de dados aqueles que melhor preenchem os requisitos pretendidos no controlo de acesso à informação do negócio e respectivos processos. Actualmente o tempo e a informação são vantagens competitivas e por esse mesmo motivo as empresas estão cada vez mais preocupadas com o facto de o aumento do volume de informação estar a tornar-se insustentável na medida que o tempo necessário para processar a informação é cada vez maior. Por esta razão muitas empresas de software, tais como Microsoft, IBM e Oracle estão numa luta por um lugar neste mercado de BI em expansão. Para que as empresas possam ser competitivas, a sua capacidade de previsão e resposta às necessidades de mercado em tempo real é requisito principal, em detrimento da existência apenas de uma reacção a uma necessidade que peca por tardia. Os produtos de BI têm fama de trabalharem apenas com dados históricos armazenados, o que faz com que as empresas não se possam basear nessas soluções quando o requisito de alguns negócios é de tempo quase real. A latência introduzida por um data warehouse é demasiada para que o desempenho seja aceitável. Desta forma, surge a tecnologia Business Activity Monitoring (BAM) que fornece análise de dados e alertas em tempo quase real sobre os processos do negócio, utilizando fontes de dados como Web Services, filas de mensagens, etc. O conceito de BAM surgiu em Julho de 2001 pela organização Gartner, sendo uma extensão orientada a eventos da área de BI. O BAM define-se pelo acesso em tempo real aos indicadores de desempenho de negócios com o intuito de aumentar a velocidade e eficácia dos processos de negócio. As soluções BAM estão a tornar-se cada vez mais comuns e sofisticadas.

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Storm- and tsunami-deposits are generated by similar depositional mechanisms making their discrimination hard to establish using classic sedimentologic methods. Here we propose an original approach to identify tsunami-induced deposits by combining numerical simulation and rock magnetism. To test our method, we investigate the tsunami deposit of the Boca do Rio estuary generated by the 1755 earthquake in Lisbon which is well described in the literature. We first test the 1755 tsunami scenario using a numerical inundation model to provide physical parameters for the tsunami wave. Then we use concentration (MS. SIRM) and grain size (chi(ARM), ARM, B1/2, ARM/SIRM) sensitive magnetic proxies coupled with SEM microscopy to unravel the magnetic mineralogy of the tsunami-induced deposit and its associated depositional mechanisms. In order to study the connection between the tsunami deposit and the different sedimentologic units present in the estuary, magnetic data were processed by multivariate statistical analyses. Our numerical simulation show a large inundation of the estuary with flow depths varying from 0.5 to 6 m and run up of similar to 7 m. Magnetic data show a dominance of paramagnetic minerals (quartz) mixed with lesser amount of ferromagnetic minerals, namely titanomagnetite and titanohematite both of a detrital origin and reworked from the underlying units. Multivariate statistical analyses indicate a better connection between the tsunami-induced deposit and a mixture of Units C and D. All these results point to a scenario where the energy released by the tsunami wave was strong enough to overtop and erode important amount of sand from the littoral dune and mixed it with reworked materials from underlying layers at least 1 m in depth. The method tested here represents an original and promising tool to identify tsunami-induced deposits in similar embayed beach environments.

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One of the most efficient approaches to generate the side information (SI) in distributed video codecs is through motion compensated frame interpolation where the current frame is estimated based on past and future reference frames. However, this approach leads to significant spatial and temporal variations in the correlation noise between the source at the encoder and the SI at the decoder. In such scenario, it would be useful to design an architecture where the SI can be more robustly generated at the block level, avoiding the creation of SI frame regions with lower correlation, largely responsible for some coding efficiency losses. In this paper, a flexible framework to generate SI at the block level in two modes is presented: while the first mode corresponds to a motion compensated interpolation (MCI) technique, the second mode corresponds to a motion compensated quality enhancement (MCQE) technique where a low quality Intra block sent by the encoder is used to generate the SI by doing motion estimation with the help of the reference frames. The novel MCQE mode can be overall advantageous from the rate-distortion point of view, even if some rate has to be invested in the low quality Intra coding blocks, for blocks where the MCI produces SI with lower correlation. The overall solution is evaluated in terms of RD performance with improvements up to 2 dB, especially for high motion video sequences and long Group of Pictures (GOP) sizes.

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Wyner-Ziv (WZ) video coding is a particular case of distributed video coding, the recent video coding paradigm based on the Slepian-Wolf and Wyner-Ziv theorems that exploits the source correlation at the decoder and not at the encoder as in predictive video coding. Although many improvements have been done over the last years, the performance of the state-of-the-art WZ video codecs still did not reach the performance of state-of-the-art predictive video codecs, especially for high and complex motion video content. This is also true in terms of subjective image quality mainly because of a considerable amount of blocking artefacts present in the decoded WZ video frames. This paper proposes an adaptive deblocking filter to improve both the subjective and objective qualities of the WZ frames in a transform domain WZ video codec. The proposed filter is an adaptation of the advanced deblocking filter defined in the H.264/AVC (advanced video coding) standard to a WZ video codec. The results obtained confirm the subjective quality improvement and objective quality gains that can go up to 0.63 dB in the overall for sequences with high motion content when large group of pictures are used.

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Wyner - Ziv (WZ) video coding is a particular case of distributed video coding (DVC), the recent video coding paradigm based on the Slepian - Wolf and Wyner - Ziv theorems which exploits the source temporal correlation at the decoder and not at the encoder as in predictive video coding. Although some progress has been made in the last years, WZ video coding is still far from the compression performance of predictive video coding, especially for high and complex motion contents. The WZ video codec adopted in this study is based on a transform domain WZ video coding architecture with feedback channel-driven rate control, whose modules have been improved with some recent coding tools. This study proposes a novel motion learning approach to successively improve the rate-distortion (RD) performance of the WZ video codec as the decoding proceeds, making use of the already decoded transform bands to improve the decoding process for the remaining transform bands. The results obtained reveal gains up to 2.3 dB in the RD curves against the performance for the same codec without the proposed motion learning approach for high motion sequences and long group of pictures (GOP) sizes.

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O objectivo deste trabalho consiste em avaliar os benefícios das Self Organizing Networks (SON), no que concerne ao planeamento e optimização de redes Long Term Evolution (LTE), não só através do seu estudo, como também através do desenvolvimento e teste de algoritmos, que permitem avaliar o funcionamento de algumas das suas principais funções. O estudo efectuado sobre as SON permitiu identificar um conjunto de funções, tais como a atribuição automática de Physical Cell Id (PCI), o Automatic Neighbour Relation (ANR) e a optimização automática de parâmetros de handover, que permitem facilitar ou mesmo substituir algumas das tarefas mais comuns em planeamento e optimização de redes móveis celulares, em particular, redes LTE. Recorrendo a um simulador LTE destinado à investigação académica, em código aberto e desenvolvido em Matlab®, foi desenvolvido um conjunto de algoritmos que permitiram a implementação das funções em questão. Para além das funções implementadas, foram também introduzidas alterações que conferem a este simulador a capacidade de representar e simular redes reais, permitindo uma análise mais coerente dos algoritmos desenvolvidos. Os resultados obtidos, para além de evidenciarem claramente o benefício dos algoritmos desenvolvidos, foram ainda comparados com os obtidos pela ferramenta profissional de planeamento e optimização Atoll®, tendo-se verificado a franca proximidade de desempenho em algumas das funções. Finalmente, foi desenvolvida uma interface gráfica que permite o desenho, configuração e simulação de cenários, bem como a análise de resultados.

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Nowadays, the cooperative intelligent transport systems are part of a largest system. Transportations are modal operations integrated in logistics and, logistics is the main process of the supply chain management. The supply chain strategic management as a simultaneous local and global value chain is a collaborative/cooperative organization of stakeholders, many times in co-opetition, to perform a service to the customers respecting the time, place, price and quality levels. The transportation, like other logistics operations must add value, which is achieved in this case through compression lead times and order fulfillments. The complex supplier's network and the distribution channels must be efficient and the integral visibility (monitoring and tracing) of supply chain is a significant source of competitive advantage. Nowadays, the competition is not discussed between companies but among supply chains. This paper aims to evidence the current and emerging manufacturing and logistics system challenges as a new field of opportunities for the automation and control systems research community. Furthermore, the paper forecasts the use of radio frequency identification (RFID) technologies integrated into an information and communication technologies (ICT) framework based on distributed artificial intelligence (DAI) supported by a multi-agent system (MAS), as the most value advantage of supply chain management (SCM) in a cooperative intelligent logistics systems. Logistical platforms (production or distribution) as nodes of added value of supplying and distribution networks are proposed as critical points of the visibility of the inventory, where these technological needs are more evident.

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Storm- and tsunami-deposits are generated by similar depositional mechanisms making their discrimination hard to establish using classic sedimentologic methods. Here we propose an original approach to identify tsunami-induced deposits by combining numerical simulation and rock magnetism. To test our method, we investigate the tsunami deposit of the Boca do Rio estuary generated by the 1755 earthquake in Lisbon which is well described in the literature. We first test the 1755 tsunami scenario using a numerical inundation model to provide physical parameters for the tsunami wave. Then we use concentration (MS. SIRM) and grain size (chi(ARM), ARM, B1/2, ARM/SIRM) sensitive magnetic proxies coupled with SEM microscopy to unravel the magnetic mineralogy of the tsunami-induced deposit and its associated depositional mechanisms. In order to study the connection between the tsunami deposit and the different sedimentologic units present in the estuary, magnetic data were processed by multivariate statistical analyses. Our numerical simulation show a large inundation of the estuary with flow depths varying from 0.5 to 6 m and run up of similar to 7 m. Magnetic data show a dominance of paramagnetic minerals (quartz) mixed with lesser amount of ferromagnetic minerals, namely titanomagnetite and titanohematite both of a detrital origin and reworked from the underlying units. Multivariate statistical analyses indicate a better connection between the tsunami-induced deposit and a mixture of Units C and D. All these results point to a scenario where the energy released by the tsunami wave was strong enough to overtop and erode important amount of sand from the littoral dune and mixed it with reworked materials from underlying layers at least 1 m in depth. The method tested here represents an original and promising tool to identify tsunami-induced deposits in similar embayed beach environments.

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The 27 December 1722 Algarve earthquake destroyed a large area in southern Portugal generating a local tsunami that inundated the shallow areas of Tavira. It is unclear whether its source was located onshore or offshore and, in any case, what was the tectonic source responsible for the event. We analyze available historical information concerning macroseismicity and the tsunami to discuss the most probable location of the source. We also review available seismotectonic knowledge of the offshore region close to the probable epicenter, selecting a set of four candidate sources. We simulate tsunamis produced by these candidate sources assuming that the sea bottom displacement is caused by a compressive dislocation over a rectangular fault, as given by the half-space homogeneous elastic approach, and we use numerical modeling to study wave propagation and run-up. We conclude that the 27 December 1722 Tavira earthquake and tsunami was probably generated offshore, close to 37 degrees 01'N, 7 degrees 49'W.

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Recently, several distributed video coding (DVC) solutions based on the distributed source coding (DSC) paradigm have appeared in the literature. Wyner-Ziv (WZ) video coding, a particular case of DVC where side information is made available at the decoder, enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill novel requirements from applications such as video surveillance, sensor networks and mobile camera phones. The quality of the side information at the decoder has a critical role in determining the WZ video coding rate-distortion (RD) performance, notably to raise it to a level as close as possible to the RD performance of standard predictive video coding schemes. Towards this target, efficient motion search algorithms for powerful frame interpolation are much needed at the decoder. In this paper, the RD performance of a Wyner-Ziv video codec is improved by using novel, advanced motion compensated frame interpolation techniques to generate the side information. The development of these type of side information estimators is a difficult problem in WZ video coding, especially because the decoder only has available some reference, decoded frames. Based on the regularization of the motion field, novel side information creation techniques are proposed in this paper along with a new frame interpolation framework able to generate higher quality side information at the decoder. To illustrate the RD performance improvements, this novel side information creation framework has been integrated in a transform domain turbo coding based Wyner-Ziv video codec. Experimental results show that the novel side information creation solution leads to better RD performance than available state-of-the-art side information estimators, with improvements up to 2 dB: moreover, it allows outperforming H.264/AVC Intra by up to 3 dB with a lower encoding complexity.

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Introdução: A produção e o uso da literatura científica são analisados, quantificados e interpretados pela bibliometria, ciência utilizada para estudos métricos da informação publicada e que estuda as questões relacionadas com a comunicação científica e a atividade científica. Objetivo: O estudo apresentado é uma análise bibliométrica da produção científica portuguesa da área da saúde indexada na Web of Science. Métodos: Analisa-se a produção referente ao período entre 1992 e final de 2011. A análise da produção científica centrou-se nas seguintes variáveis: categorias de classificação da Web of Science, tipologia de documentos indexados, títulos de revistas, distribuição por anos de publicação, afiliação institucional, idiomas, países de origem dos autores com quem foram estabelecidas relações de parceria científica e quem facultou os financiamentos à investigação científica. Resultados: Foram contabilizados 34.208 trabalhos. Destes, o artigo é a forma mais utilizada pelos autores portugueses para a divulgação dos resultados de investigação (58,5%). A década mais recente é contemplada com 75,4% dos registos. A maioria da produção com visibilidade internacional é oriunda de universidades e de centros de investigação hospitalar; institutos, laboratórios da indústria farmacêutica e universidades estrangeiras têm valores residuais. A colaboração com outros investigadores internacionais destaca-se no caso da Europa (73,2%). O financiamento da investigação científica é suportado basicamente pela Fundação para a Ciência e Tecnologia (59,5%), seguida da Comissão Europeia (17,8%). O inglês é o idioma mais usado para a divulgação dos resultados de investigação nacional na área da saúde (97,8%). Conclusões: O uso de bases de dados ou de plataformas científicas para estudos bibliométricos é um processo moroso e difícil. O total de trabalhos em análise foi sempre o mesmo mas, em algumas variáveis, os valores não coincidem, quer porque alguns dos registos foram classificados em mais do que uma categoria temática, quer pelos trabalhos multidisciplinares oriundos das mesmas instituições, quer pelos trabalhos de colaboração internacional. Também no presente estudo os artigos são o veículo privilegiado para a divulgação dos resultados científicos. Apontamento final: deve encorajar-se a utilização de outras plataformas científicas e de outras bases de dados para uma mais completa recuperação da produção científica nacional na área da saúde. Introduction: The production and the use of the scientific literature are analyzed, quantified and interpreted by bibliometry. Bibliometry is the science used in published information metric studies and studies the questions of scientific communication and the scientific production. Aim of the study: This study presents a bibliometric analysis of the indexed Web of Science Portuguese scientific production in the health field. Methods: We analyzed the production from 1992 to the end of 2011. This analysis focused in several variables: general categories areas of Web of Science, indexed document types, source titles, publication years, group/corporate authors, languages, identification of the countries with scientific partnerships and identification of the funding agencies for scientific research. Results: We found 34.208 works. From this, the article is the most common channel for disseminating the research results (58.5%). The most recent decade has 75.4% of the total of records. Most of the production with international visibility becomes from universities and hospital research centers; institutes, pharmaceutical labs or foreign universities have residual values. Collaborating with other international researchers is very common, particularly with Europe (73.2%). In general, the Fundação para a Ciência e Tecnologia supports the scientific research (59.5%), followed by the European Commission (17.8%). The language commonly used for disseminating the research results in health is the English (97.8%). Conclusions: Using databases or scientific platforms for bibliometric studies is a hard and difficult process. The total of works analyzed was always the same but, with some variables, the numbers does not coincide: a) some of the registries were classified in several categories; b) some of the multidisciplinary works were from the same institution; c) the large number of international partnership. In this study, articles are the privileged way for disseminating the scientific results. A last thought: the use of other scientific platforms and databases should be encouraged for a more complete retrieval of the national research production in health.

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Preliminary version

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Introdução: A produção e o uso da literatura científica são analisados, quantificados e interpretados pela bibliometria, ciência utilizada para estudos métricos da informação publicada e que estuda as questões relacionadas com a comunicação científica e a atividade científica. Objetivo: O estudo apresentado é uma análise bibliométrica da produção científica portuguesa da área da saúde indexada na Web of Science. Métodos: Analisa-se a produção referente ao período entre 1992 e final de 2011. A análise da produção científica centrou-se nas seguintes variáveis: categorias de classificação da Web of Science, tipologia de documentos indexados, títulos de revistas, distribuição por anos de publicação, afiliação institucional, idiomas, países de origem dos autores com quem foram estabelecidas relações de parceria científica e quem facultou os financiamentos à investigação científica. Resultados: Foram contabilizados 34.208 trabalhos. Destes, o artigo é a forma mais utilizada pelos autores portugueses para a divulgação dos resultados de investigação (58,5%). A década mais recente é contemplada com 75,4% dos registos. A maioria da produção com visibilidade internacional é oriunda de universidades e de centros de investigação hospitalar; institutos, laboratórios da indústria farmacêutica e universidades estrangeiras têm valores residuais. A colaboração com outros investigadores internacionais destaca-se no caso da Europa (73,2%). O financiamento da investigação científica é suportado basicamente pela Fundação para a Ciência e Tecnologia (59,5%), seguida da Comissão Europeia (17,8%). O inglês é o idioma mais usado para a divulgação dos resultados de investigação nacional na área da saúde (97,8%). Conclusões: O uso de bases de dados ou de plataformas científicas para estudos bibliométricos é um processo moroso e difícil. O total de trabalhos em análise foi sempre o mesmo mas, em algumas variáveis, os valores não coincidem, quer porque alguns dos registos foram classificados em mais do que uma categoria temática, quer pelos trabalhos multidisciplinares oriundos das mesmas instituições, quer pelos trabalhos de colaboração internacional. Também no presente estudo os artigos são o veículo privilegiado para a divulgação dos resultados científicos. Apontamento final: deve encorajar-se a utilização de outras plataformas científicas e de outras bases de dados para uma mais completa recuperação da produção científica nacional na área da saúde. Introduction: The production and the use of the scientific literature are analyzed, quantified and interpreted by bibliometry. Bibliometry is the science used in published information metric studies and studies the questions of scientific communication and the scientific production. Aim of the study: This study presents a bibliometric analysis of the indexed Web of Science Portuguese scientific production in the health field. Methods: We analyzed the production from 1992 to the end of 2011. This analysis focused in several variables: general categories areas of Web of Science, indexed document types, source titles, publication years, group/corporate authors, languages, identification of the countries with scientific partnerships and identification of the funding agencies for scientific research. Results: We found 34.208 works. From this, the article is the most common channel for disseminating the research results (58.5%). The most recent decade has 75.4% of the total of records. Most of the production with international visibility becomes from universities and hospital research centers; institutes, pharmaceutical labs or foreign universities have residual values. Collaborating with other international researchers is very common, particularly with Europe (73.2%). In general, the Fundação para a Ciência e Tecnologia supports the scientific research (59.5%), followed by the European Commission (17.8%). The language commonly used for disseminating the research results in health is the English (97.8%). Conclusions: Using databases or scientific platforms for bibliometric studies is a hard and difficult process. The total of works analyzed was always the same but, with some variables, the numbers does not coincide: a) some of the registries were classified in several categories; b) some of the multidisciplinary works were from the same institution; c) the large number of international partnership. In this study, articles are the privileged way for disseminating the scientific results. A last thought: the use of other scientific platforms and databases should be encouraged for a more complete retrieval of the national research production in health.

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Storm- and tsunami-deposits are generated by similar depositional mechanisms making their discrimination hard to establish using classic sedimentologic methods. Here we propose an original approach to identify tsunami-induced deposits by combining numerical simulation and rock magnetism. To test our method, we investigate the tsunami deposit of the Boca do Rio estuary generated by the 1755 earthquake in Lisbon which is well described in the literature. We first test the 1755 tsunami scenario using a numerical inundation model to provide physical parameters for the tsunami wave. Then we use concentration (MS. SIRM) and grain size (chi(ARM), ARM, B1/2, ARM/SIRM) sensitive magnetic proxies coupled with SEM microscopy to unravel the magnetic mineralogy of the tsunami-induced deposit and its associated depositional mechanisms. In order to study the connection between the tsunami deposit and the different sedimentologic units present in the estuary, magnetic data were processed by multivariate statistical analyses. Our numerical simulation show a large inundation of the estuary with flow depths varying from 0.5 to 6 m and run up of similar to 7 m. Magnetic data show a dominance of paramagnetic minerals (quartz) mixed with lesser amount of ferromagnetic minerals, namely titanomagnetite and titanohematite both of a detrital origin and reworked from the underlying units. Multivariate statistical analyses indicate a better connection between the tsunami-induced deposit and a mixture of Units C and D. All these results point to a scenario where the energy released by the tsunami wave was strong enough to overtop and erode important amount of sand from the littoral dune and mixed it with reworked materials from underlying layers at least 1 m in depth. The method tested here represents an original and promising tool to identify tsunami-induced deposits in similar embayed beach environments.