2011
Autores
Gonçalves, V; Pollin, S;
Publicação
2011 IEEE International Symposium on Dynamic Spectrum Access Networks, DySPAN 2011
Abstract
The main challenge to allow for use of the so-called TV White Spaces is to achieve a reliable approach for detecting presence of licensed users ensuring that harmful interference to television signals and other incumbent services does not occur. In the current debate, there is a trend towards the use of a geo-location database only, driven by the fear that other techniques fail to achieve the required detection reliability. Therefore, in this paper we intend to assess if the technical and business value of sensing in the context of TVWS should be neglected. Taking in consideration the discussion on the adequate technical requirements currently taking place in Europe and the USA, the cost and performance of the proposed techniques for local sensing, distributed sensing and geo-location database are compared through a simple model. As a result, we conclude that using a distributed sensing solution based on low-cost low-power sensing engines, we could achieve a solution with hardware and energy costs a par with the geo-location database. However, by assessing the costs and business impacts for stakeholders such as manufacturers and White Spaces Service Providers we conclude that in the geo-location database solution, regulators, White Spaces Service Providers, White Spaces Database Providers and consumers may incur additional infrastructure, maintenance and administrative costs compared to a distributed sensing solution. Consequently, we are of the opinion that the distributed sensing solution in the context of TVWS does indeed present value and its business and technical impact should be considered in further research and regulatory activities. © 2011 IEEE.
2011
Autores
Carvalho, P; Oliveira, B; Barros, R; Padrao, P; Moreira, P; Teixeira, VH;
Publicação
INTERNATIONAL JOURNAL OF SPORT NUTRITION AND EXERCISE METABOLISM
Abstract
Twelve adolescent athletes underwent, in a crossover-design study, 3 separate 90-min training sessions in the following conditions: no fluid ingestion allowed (NF), ad libitum ingestion of water (W), and ad libitum ingestion of a commercial 8% carbohydrate-electrolyte sports beverage (CSB). After each session athletes performed a set of basketball drills (2-point, 3-point, and free-throw shootout, suicide sprints, and defensive zigzags). Body weight (before and after sessions), rating of perceived exertion (RPE), urine color, and beverage acceptability were determined in each session. Athletes also completed a survey about their knowledge and behaviors regarding hydration and fluid replacement. The percentage of weight loss was significantly higher in NF (2.46% +/- 0.87%) than in the other 2 conditions (W, 1.08% +/- 0.67%, p = .006; CSB, 0.65% +/- 0.62%, p = .001) but also higher in W than CSB (p = .012). RPE was higher in NF (16.8 +/- 1.96) than in the W (14.2 +/- 1.99, p = .004) and CSB (13.3 +/- 2.06, p = .002) trials. Athletes' fluid intake was positively correlated with proper self-reported behaviors (r = .75, p = .005) and knowledge (r = .76, p = .004) about fluid and hydration. In conclusion, fluid restriction during exercise was associated with a greater level of dehydration and increased perceived exertion but had no impact on basketball performance compared with ad libitum drinking of water or a CSB. Athletes with more knowledge about hydration and better self-reported hydration behaviors ingested more fluids during training sessions.
2011
Autores
Barbosa, LS; Barbosa, MAC; Rodrigues, CJ;
Publicação
12TH INTERNATIONAL SYMPOSIUM ON SYMBOLIC AND NUMERIC ALGORITHMS FOR SCIENTIFIC COMPUTING (SYNASC 2010)
Abstract
Software connectors are external coordination devices which ensure the flow of data and enforce synchronization constraints within a component's network. The specification of software connectors through which context dependent behaviour is correctly propagated remains an open, non trivial issue in their semantics. This paper, building on previous work by the authors, revisits this problem and introduces a model in which context awareness is suitably handled.
2011
Autores
Shapiro, M; Preguiça, NM; Baquero, C; Zawirski, M;
Publicação
Bulletin of the EATCS
Abstract
2011
Autores
Campos, MJ; Correia, ME; Antunes, L;
Publicação
2011 IEEE INTERNATIONAL CARNAHAN CONFERENCE ON SECURITY TECHNOLOGY (ICCST)
Abstract
Many heterogeneous and highly specialized software applications for eHealth were implemented and deployed by diverse health organizations, such as public and private hospitals and health care centers. The rational management of these eHealth assets together with their efficient and interoperable integration represents today a major hitherto unresolved challenge for the health sector at a global level. One of the present implications is the serious interoperability issues that arise by the lack of widely accepted standards for the homogeneous integration of the diverse identity and authentication mechanisms used by the eHealth applications ecosystem. Unfortunately this has not yet been a major infrastructure concern for the eHealth context and thus constitutes a major road block for the realization of these applications full integration potential. In this work a high level model and some critical infrastructure components are proposed. Together with the Portuguese eID smart-card, allowed to delineate a novel and more flexible infrastructure for secure identity management and authentication services for eHealth. The secure privacy oriented identity infrastructure proposed fits well the highly demanding and specific needs of a heterogeneous and integrated modern identity infrastructure for eHealth applications, precisely because it provides strong foundations, upon which more reliable, secure, trustworthy and inter-operable eHealth applications can be built.
2011
Autores
Melo, LB; Angelo, N; Alberto, N; Marques, C; Monteiro, J; Rego, G; Caldas, P; Nogueira, R;
Publicação
INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS
Abstract
This paper presents a comparative study of the behaviour of different kinds of optical fibre sensors in response to high temperatures. It compares the performance of regenerated fibre Bragg gratings (FBGs) written in hydrogen-loaded and non-loaded fibres with long period gratings (LPGs) written through the two different processes of ultraviolet (UV) irradiation and electrical arc discharges. This work shows the importance of the use of hydrogen-loaded fibres to achieve regenerated FBGs capable of withstanding high temperatures as high as 955 degrees C. In addition, the results demonstrated that LPGs recorded by electric arc discharges have higher thermal resistance than LPGs written by UV radiation.
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