60 research outputs found

    Phase shift optimization algorithm for achievable rate maximization in reconfigurable intelligent surface-assisted THz communications

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    Terahertz (THz) band communications are considered a crucial technology to support future applications, such as ultra-high bit rate wireless local area networks, in the next generation of wireless communication systems. In this work, we consider an ultra-massive multiple-input multiple-output (UM-MIMO) THz communication system operating in a typical indoor scenario where the direct link between the transmitter and receiver is obstructed due to surrounding obstacles. To help establish communication, we assume the aid of a nearby reconfigurable intelligent surface (RIS) whose phase shifts can be adjusted. To configure the individual phase shifts of the RIS elements, we formulate the problem as a constrained achievable rate maximization. Due to the typical large dimensions of this optimization problem, we apply the accelerated proximal gradient (APG) method, which results in a low complexity algorithm that copes with the non-convex phase shift constraint through simple element-wise normalization. Our numerical results demonstrate the effectiveness of the proposed algorithm even when considering realistic discrete phase shifts’ quantization and imperfect channel knowledge. Furthermore, comparison against existing alternatives reveals improvements between 30% and 120% in terms of range, for a reference rate of 100 Gbps when using the proposed approach with only 81 RIS elements.info:eu-repo/semantics/publishedVersio

    Papel de la tecnología en la educación científica: una dimensión olvidada

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    El actual movimiento en pro de una 'alfabetización tecnológica' ha venido a cuestionar algunos supuestos implícitos en la orientación de la educación científica que se traducen, de facto, en el olvido de la dimensión tecnológica. En este trabajo se analizan dichos supuestos y se extraen algunas implicaciones que representan un enriquecimiento de la educación científica con la incorporación de aspectos esenciales hasta aquí ignorados. Se pretende, así mismo, mostrar la existencia de una convergencia básica en torno a unas propuestas de enseñanza-aprendizaje de las ciencias que superen las estrategias basadas en la simple transmisión-recepción de conocimientos, subrayando la contribución de la dimensión tecnológica al desarrollo de dichas propuestas

    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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