2012
Authors
Ferreira, MS; Schuster, K; Kobelke, J; Santos, JL; Frazao, O;
Publication
OPTICS LETTERS
Abstract
A spatial optical filter based on a hollow-core silica tube is proposed. Because of the hollow-core dimensions, it is possible to obtain a periodical spatial filter ranging from 1200 to 1700 nm with a channel spacing of 2.64 THz. The bandwidth is approximately 5.32 nm, and the isolation loss is similar to 30 dB. The optical losses are approximately similar to 0.67 dB/mm for a wavelength of 1500 nm. The 40 mm long spatial optical filter is tested as a sensing element and subjected to different physical parameters. The spatial optical filter is wavelength sensitive to strain and temperature, while for refractive-index variations there is an optical power dependency. This fiber structure can be used as a sensing element for extreme conditions, such as in very high temperature environments, where it presents a sensitivity of 27.5 pm degrees C-1. (C) 2012 Optical Society of America
2012
Authors
Lucas, A; Costa Neto, RC; Silva, CA;
Publication
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
Abstract
Hydrogen and electric vehicle technologies are being considered as possible solutions to mitigate environmental burdens and fossil fuel dependency. Life cycle analysis (LCA) of energy use and emissions has been used with alternative vehicle technologies to assess the Well-to-Wheel (WTW) fuel cycle or the Cradle-to-Grave (CTG) cycle of a vehicle's materials. Fuel infrastructures, however, have thus far been neglected. This study presents an approach to evaluate energy use and CO2 emissions associated with the construction, maintenance and decommissioning of energy supply infrastructures using the Portuguese transportation system as a case study. Five light-duty vehicle technologies are considered: conventional gasoline and diesel (ICE), pure electric (EV), fuel cell hybrid (FCHEV) and fuel cell plug-in hybrid (FC-PHEV). With regard to hydrogen supply, two pathways are analysed: centralised steam methane reforming (SMR) and on-site electrolysis conversion. Fast, normal and home options are considered for electric chargers. We conclude that energy supply infrastructures for FC vehicles are the most intensive with 0.03-0.53 MJ(eq)/MJ emitting 0.7-27.3 g CO2eq/MJ of final fuel. While fossil fuel infrastructures may be considered negligible (presenting values below 2.5%), alternative technologies are not negligible when their overall LCA contribution is considered. EV and FCHEV using electrolysis report the highest infrastructure impact from emissions with approximately 8.4% and 8.3%, respectively. Overall contributions including uncertainty do not go beyond 12%. Copyright
2012
Authors
Pacheco, AP; Claro, J; Oliveira, T;
Publication
WIT Transactions on Ecology and the Environment
Abstract
Rekindles can represent a high burden on wildland fire suppression resources, but despite the relevance of this phenomenon in Portugal, related research is still scarce. Seeking to contribute to address this gap, the purpose of this study was to organize and provide an overview of the problem of rekindles in Portugal, and to verify whether evidence exists that the high proportion of rekindles in Portugal is related to the double duty of Portuguese firefighters to perform initial attack and mop-up operations. Our study included informal meetings, formal recorded interviews, dispatch centre visits, actual rekindle observation, and an analysis of the National Forest Authority database. From the study of genealogies of rekindles, we concluded that 17.2% additional forest fires (rekindles in successive generations) had their origin in only 7.4% of primary fires. Through linear regression analysis, we found that their proportions increase in days with more occurrences, preliminarily supporting the hypothesis of premature abandonment of mop-up operations, as a result from the pressure to immediately attack starting fires by the same crews. A more detailed analysis of two representative districts highlighted specific organizational and natural challenges to successful mop-up efforts and provided further evidence of the hazardousness of rekindles. © 2012 WIT Press.
2012
Authors
Masci, P; Furniss, D; Curzon, P; Harrison, MD; Blandford, A;
Publication
Software Engineering for Resilient Systems - 4th International Workshop, SERENE 2012, Pisa, Italy, September 27-28, 2012. Proceedings
Abstract
This paper reports the lessons learnt about the benefits of using a formal verification tool like PVS to support field studies. The presentation is based on a field study in the healthcare domain which was designed to investigate the resilience of human behaviour in an oncology ward of a hospital. The automated reasoning tool PVS was used systematically to compare actual practice observed during the field study with normative behaviour described for example by user manuals for the devices involved. The approach helped (i) identify latent situations that could lead to hazard, and (ii) suggest situations likely to warrant further investigation as part of the field study. The main contribution of this paper is a set of detailed examples that illustrate how we used PVS during the field study, and how the tool led to insights. © 2012 Springer-Verlag.
2012
Authors
Santos, V; Gonçalves, R;
Publication
7th Mediterranean Conference on Information Systems, MCIS 2012, Guimarães, Portugal, September 8-10, 2012, Short Papers Proceedings
Abstract
2012
Authors
Cunha, J; Fernandes, JP; Mendes, J; Saraiva, J;
Publication
2012 1st International Workshop on User Evaluation for Software Engineering Researchers, USER 2012 - Proceedings
Abstract
Spreadsheets are widely recognized as popular programming systems with a huge number of spreadsheets being created every day. Also, spreadsheets are often used in the decision processes of profit-oriented companies. While this illustrates their practical importance, studies have shown that up to 90% of real-world spreadsheets contain errors. © 2012 IEEE.
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