66 research outputs found

    A Network Algorithm for 3D/2D IPTV Distribution using WiMAX and WLAN Technologies

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    The final publication is available at link.springer.comThe appearance of new broadband wireless technologies jointly with the ability to offer enough quality of service to provide IPTV over them, have made possible the mobility and ubiquity of any type of device to access the IPTV network. The minimum bandwidth required in the access network to provide appropriate quality 3D/2D IPTV services jointly with the need to guarantee the Quality of Experience (QoE) to the end user, makes the need of algorithms that should be able to combine different wireless standards and technologies. In this paper, we propose a network algorithm that manages the IPTV access network and decides which type of wireless technology the customers should connect with when using multiband devices, depending on the requirements of the IPTV client device, the available networks, and some network parameters (such as the number of loss packets and packet delay), to provide the maximum QoE to the customer. The measurements taken in a real environment from several wireless networks allow us to know the performance of the proposed system when it selects each one of them. The measurements taken from a test bench demonstrate the success of our system.This work has been partially supported by the Polytechnic University of Valencia, though the PAID-15-10 multidisciplinary projects, by the Instituto de Telecomunicacoes, Next Generation Networks and Applications Group (NetGNA), Portugal, and by National Funding from the FCT - Fundacao para a Ciencia e a Tecnologia through the PEst-OE/EEI/LA0008/2011 Project.Lloret, J.; Cánovas Solbes, A.; Rodrigues, JJPC.; Lin, K. (2013). A Network Algorithm for 3D/2D IPTV Distribution using WiMAX and WLAN Technologies. Multimedia Tools and Applications. 67(1):7-30. https://doi.org/10.1007/s11042-011-0929-4S730671Abukharis S, MacKenzie R, Farrell TO (2009) Improving QoS of Video Transmitted Over 802.11 WLANs Using Frame Aggregation. 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Microw Opt Technol Lett 52(2):471–474IEEE 802.11 Working Group, At http://www.ieee802.org/11/index.shtml [last access: July 2011]IEEE Std 802.11™-2007 - IEEE Standard for Information Technology— Telecommunications and information exchange between systems— Local and metropolitan area networks—Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) SpecificationsIEEE Std 802.16™-2009, IEEE Standard for Local and metropolitan area networks, Part 16: Air Interface for Broadband Wireless Access Systems. At http://standards.ieee.org/getieee802/download/802.16-2009.pdf [last access: July 2011]inCode Telecom group Inc. (2006) The Quad-Play—the First Wave of the Converged Services Evolution. 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IEEE Commun Mag 43(10):49–56Lai C, Min Chen (2011) Playback-Rate Based Streaming Services for Maximum Network Capacity in IP Multimedia Subsystem, IEEE System Journal, doi: 10.1109/JSYST.2011.2165190Lee K-H, Trong ST, Lee B-G, Kim Y-T (2008) QoS-Guaranteed IPTV Service Provisioning in Home Network with IEEE 802.11e Wireless LAN,” IEEE Network Operations and Management Symposium. pp 71-76Marcelo Atenas, Sandra Sendra, Miguel Garcia, Jaime Lloret (2010) IPTV Performance in IEEE 802.11n WLANs, IEEE Global Communications Conference (IEEE Globecomm 2010), Miami (USA), December 6–10Miguel Garcia, Jaime Lloret, Miguel Edo, Raquel Lacuesta (2009) IPTV Distribution Network Access System Using WiMAX and WLAN Technologies, International Symposium on High Performance Distributed Computing (HPDC 2009), Munich (Germany), June 11–13Park AH, Choi JK (2007) “QoS guaranteed IPTV service over Wireless Broadband network”, The 9th Int. 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    The introduction of modern physics: overcoming a deformed vision of science

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    In this paper, we try to show initially that modern physics is usually introduced in high school curricula without reference to the difficulties of classical physics, simply juxtaposing the two paradigms or even mixing them up. As a result, serious misconceptions arise. We then present another way of introducing modern physics, based on a contructivist view of science learning, and give some results obtained with the new materials

    History and philosophy of science in Biology teaching

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    Neste trabalho, buscamos evidenciar a concepção de História da Biologia que é veiculada nos livros didáticos. Para tanto, analisamos três coleções de livros de Biologia destinados ao Ensino Médio, e alguns livros universitários usados em cursos de formação de professores. Ao analisar este material curricular foi possível observar que a história apresentada é desvinculada do contexto cultural de cada período histórico, o que pode levar o aluno a construir uma falsa representação da ciência e do fazer científico.In this work, we search forto evidences the conception of the History of Biology being is propagated in textbooks. We analyze three Biology book collections designed estined forto middle schooledium education, and some university books used in teacher education courses. When analyzing this curricular material it was possible to observe that the history of biology presented is disengaged from entailedofthe cultural context of each historical period, and this what can lead the student to construct a false representation of science and of scientific meaning making

    Experimental and theoretical studies of electrothermal waves.

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    Determining the efficiency of optical sources using a smartphone's ambient light sensor

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    This work reports the use of a smartphone’s ambient light sensor as a valuable tool to study and characterize the efficiency of an optical source. Here, we have measured both luminous efficacy and efficiency of several optical sources (incandescent bulb and halogen lamp) as a function of the electric power consumed and the distance to the optical detector. The illuminance of LEDs as a function of the distance to the optical detector is characterized for different wavelength emissions. Analysis of the results confirms an inverse-square law of the illuminance with the detector–source distance and shows good agreement with values obtained by classical experiments. This experience will trigger awareness in students in terms of sustainability, light propagation and efficiency of different optical sources.The authors would like to thank the Institute of Education Sciences, Universitat Politecnica de Valencia (Spain), for the support of the teaching innovation groups MOMA and e-MACAFI, and the financial support of Project PIME-2015-B18. The authors also acknowledge the financial support of project EDU2015-69701-P by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund. J A Sans acknowledges Ramon y Cajal fellowship program for financial support.Sans-Tresserras, JÁ.; Gea Pinal, J.; Giménez Valentín, MH.; Esteve, AR.; Solbes, J.; Monsoriu Serra, JA. (2017). Determining the efficiency of optical sources using a smartphone's ambient light sensor. European Journal of Physics. 38(2):1-9. https://doi.org/10.1088/1361-6404/aa51a9S1938

    A Decade of Lost Growth: Economic Policy in Spain through the Great Recession

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    This is an Accepted Manuscript of an article published by Taylor & Francis in South European Society and Politics, available online at: http://www.tandfonline.com/doi/full/10.1080/13608746.2017.1301065. Under embargo. Embargo end date: 27 June 2018. Keith Salmon, 'A decade of lost growth: economic policy in Spain through the Great Recession', South European Society and Politics, first published online 27 March 2017.In 2008 the Spanish economy sank into recession, returning to growth in 2014. This paper explores the policies that were pursued by two successive governments to escape the recession. It comments on one of the most contentious strategies, that of austerity, and underlines the constraints on policy imposed by membership of the European Monetary Union (EMU) and a decentralised state. The Great Recession and accompanying austerity policy were associated with huge social and economic costs. Policy targets on the debt and deficit were not met. This experience, together with the broader sluggish growth in Europe and the political consequences associated with austerity, pointed to the need for a new policy mix.Peer reviewedFinal Accepted Versio

    Technology as 'Applied Science': a Serious Misconception that Reinforces Distorted and Impoverished Views of Science

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    The current consideration of technology as 'applied science', this is to say, as something that comes 'after' science, justifies the lack of attention paid to technology in science education. In our paper we question this simplistic view of the science-technology relationship, historically rooted in the unequal appreciation of intellectual and manual work, and we try to show how the absence of the technological dimension in science education contributes to a na¿ ve and distorted view of science which deeply affects the necessary scientific and technological literacy of all citizens
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