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Sökning: WFRF:(Alves Martins Wallace)

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  • 2021
  • swepub:Mat__t
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5.
  • Abazov, V. M., et al. (författare)
  • The upgraded DO detector
  • 2006
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
  • Tidskriftsartikel (refereegranskat)abstract
    • The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
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  • Abdullah, Zaid, et al. (författare)
  • Cooperative Hybrid Networks with Active Relays and RISs for B5G : Applications, Challenges, and Research Directions
  • 2022
  • Ingår i: IEEE Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1284. ; , s. 1-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Among the recent advances and innovations in wireless technologies, reconfigurable intelligent surfaces (RISs) have received much attention and are envisioned to be one of the enabling technologies for beyond 5G (B5G) networks. On the other hand, active (or classical) cooperative relays have played a key role in providing reliable and power-efficient communications in previous wireless generations. In this article, we focus on hybrid network architectures that amalgamate both active relays and RISs. The operation concept and protocols of each technology are first discussed. Subsequently, we present multiple use cases of cooperative hybrid networks where both active relays and RISs can coexist harmoniously for enhanced rate performance. Furthermore, a case study is provided which demonstrates the achievable rate performance of a communication network assisted by either an active relay, an RIS, or both, and with different relaying protocols. Finally, we provide the reader with the challenges and key research directions in this area.
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7.
  • Fonseca, JA, et al. (författare)
  • [ARIA 2019: An Integrated Care Pathway for Allergic Rhinitis in Portugal]
  • 2021
  • Ingår i: Acta medica portuguesa. - : Ordem dos Medicos. - 1646-0758 .- 0870-399X. ; 34:2, s. 145-158
  • Tidskriftsartikel (refereegranskat)abstract
    • A iniciativa Allergic Rhinitis and Its Impact on Asthma (ARIA) teve início há mais de 20 anos e tem elaborado e disseminado orientações baseadas em evidência, e desenvolvido projetos na área da rinite alérgica. Esta iniciativa está atualmente focada em proporcionar orientações centradas no doente que contribuam para um percurso integrado entre os vários níveis de cuidados e que tirem partido de soluções digitais, tendo sido recomendada a introdução na prática clínica de percursos assistenciais integrados. Neste artigo descrevemos a adaptação para Portugal do documento ARIA Integrated Care Pathways. Após breve revisão sobre a epidemiologia e o impacto da rinite alérgica em Portugal e das atividades realizadas em Portugal no âmbito da iniciativa ARIA, é descrito o conjunto alargado de conhecimento utilizado para o desenvolvimento das recomendações para o tratamento farmacológico da rinite alérgica, recomendações essas baseadas na metodologia GRADE, evidência do mundo real adquirida por tecnologia móvel (mHealth) e resultante de estudos de câmara de exposição alergénica. Em seguida, são resumidos os percursos assistenciais integrados para imunoterapia com alergénios produzidas em 2019. Considera-se a imunoterapia com alergénios um exemplo de medicina de precisão e em que a utilização de tecnologias mHealth permitirá melhorar a estratificação para seleção dos doentes e monitorização da resposta. Estas recomendações foram consideradas como ‘boas práticas’ dos cuidados integrados centrados no doente apoiados por sistemas digitais da DG Santé (Direção Geral de Saúde e de Segurança Alimentar da União Europeia) e representam a estratégia de gestão da mudança da fase 4 do ARIA.
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  • Martins, Wallace Alves, et al. (författare)
  • Frequency-packed Faster-than-Nyquist Signaling via Symbol-level Precoding for Multi-user MISO Redundant Transmissions
  • 2022
  • Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1276 .- 1558-2248. ; , s. 1-1
  • Tidskriftsartikel (refereegranskat)abstract
    • This work addresses the issue of interference generated by co-channel users in downlink multi-antenna multicarrier systems with frequency-packed faster-than-Nyquist (FTN) signaling. The resulting interference stems from an aggressive strategy for enhancing the throughput via frequency reuse across different users and the squeezing of signals in the time-frequency plane beyond the Nyquist limit. The spectral efficiency is proved to be increasing with the frequency packing and FTN acceleration factors. The lower bound for the FTN sampling period that guarantees information losslesness is derived as a function of the transmitting-filter roll-off factor, the frequency-packing factor, and the number of subcarriers. Space-time-frequency symbol-level precoders (SLPs) that trade off constructive and destructive interblock interference (IBI) at the single-antenna user terminals are proposed. Redundant elements are added as guard interval to cope with vestigial destructive IBI effects. The proposals can handle channels with delay spread longer than the multicarrier-symbol duration. The receiver architecture is simple, for it does not require digital multicarrier demodulation. Simulations indicate that the proposed SLP outperforms zero-forcing precoding and achieves a target balance between spectral and energy efficiencies by controlling the amount of added redundancy from zero (full IBI) to half (destructive IBI-free) the group delay of the equivalent channel. 
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9.
  • Ntontin, Konstantinos, et al. (författare)
  • Autonomous Reconfigurable Intelligent Surfaces Through Wireless Energy Harvesting
  • 2022
  • Ingår i: 95th IEEE Vehicular Technology Conference - Spring, VTC 2022-Spring. - : Institute of Electrical and Electronics Engineers (IEEE).
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we examine the potential for a reconfigurable intelligent surface (RIS) to be powered by energy harvested from information signals. This feature might be key to reap the benefits of RIS technology's lower power consumption compared to active relays. We first identify the main RIS power-consuming components and then propose an energy harvesting and power consumption model. Furthermore, we formulate and solve the problem of the optimal RIS placement together with the amplitude and phase response adjustment of its elements in order to maximize the signal-to-noise ratio (SNR) while harvesting sufficient energy for its operation. Finally, numerical results validate the autonomous operation potential and reveal the range of power consumption values that enables it.
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10.
  • Ntontin, Konstantinos, et al. (författare)
  • Wireless Energy Harvesting for Autonomous Reconfigurable Intelligent Surfaces
  • 2023
  • Ingår i: IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING. - : Institute of Electrical and Electronics Engineers (IEEE). - 2473-2400. ; 7:1, s. 114-129
  • Tidskriftsartikel (refereegranskat)abstract
    • In the current contribution, we examine the feasibility of fully-energy-autonomous operation of reconfigurable intelligent surfaces (RIS) through wireless energy harvesting (EH) from incident information signals. Towards this, we first identify the main RIS energy-consuming components and present a suitable and accurate energy-consumption model that is based on the recently proposed integrated controller architecture and includes the energy consumption needed for channel estimation. Building on this model, we introduce a novel RIS architecture that enables EH through RIS unit-cell (UC) splitting. Subsequently, we introduce an EH policy, where a subset of the UCs is used for beamsteering, while the remaining UCs absorb energy. In particular, we formulate a subset al.ocation optimization problem that aims at maximizing the signal-to-noise ratio (SNR) at the receiver without violating the RIS's energy consumption demands. As a problem solution, we present low-complexity heuristic algorithms. The presented numerical results reveal the feasibility of the proposed architecture and the efficiency of the presented algorithms with respect to both the optimal and very high-complexity brute-force approach and the one corresponding to random subset selection. Furthermore, the results reveal how important the placement of the RIS as close to the transmitter as possible is, for increasing the harvesting effectiveness.
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