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[en] In this work, the photodegradation of a polymer optical fiber with Rhodamine doped cladding as a function of illumination time and excitation intensity is presented. To show the effect of photodegradation on different bulk geometries and environments, the photodegradation from a dye doped preform and a PMMA thick film is also evaluated. The reversible and the irreversible degradation of the florescent material were quantified under an established excitation scheme. To this purpose, a four-level system to model the photodegradation rates and its relation with the population of the states is presented and it is used to justify a possible underlying mechanism. The obtained results suggest an increase of one order of magnitude in the stability (lifetime) of the polymer optical fiber with respect to the preform or the thick film geometry stability.
Journal
[en] Measurements of natural global and diffuse illuminance on four vertical surfaces exposed to north, east, south and west have been carried out at Arcavacata di Rende (Italy). In the work the mean hourly values of the global and diffuse luminous efficacy measured in the period of a year are presented. The hourly data have been compared with the predictions of many calculation models. The comparisons show that, for global efficacy, the differences among the various models are not significant, and the use of a model with a constant value of efficacy gives good predictions of global illuminance. For the prediction of diffuse illuminance the different models behave in a similar way if their coefficients are recalculated and, again, the use of a constant diffuse efficacy provides a good estimate of diffuse illuminance on vertical surfaces
Journal
[en] Failures on provincial highways are usually thought to refer to large scale component failures such as bridge collapses. Small scale components also experience failure and can cause expensive repairs and threats to the motoring public. The following case histories illustrate some of these small scale failures that can carry large impacts. The first two case histories involve cable and bracket failures of high mast lighting systems. The third examines the rapid failure of bolts used for bridge deck expansion joints and the fourth is an exfoliation corrosion failure of an aluminum splice used on aluminum overhead sign structures. (author)
Source
Elboujdaini, M. (CANMET, Ottawa, Ontario (Canada)); Ghali, E. (Laval Univ., Quebec City, Quebec (Canada)); Zheng, W. (CANMET, Ottawa, Ontario (Canada)) (eds.); Metallurgical Society of CIM, Montreal, Quebec (Canada); 310 p; ISBN 1-894475-06-2; 
; 2000; p. 249-251; Proceedings of the international symposium on environmentally induced cracking of metals; Ottawa, Ontario (Canada); 20-23 Aug 2000
; 2000; p. 249-251; Proceedings of the international symposium on environmentally induced cracking of metals; Ottawa, Ontario (Canada); 20-23 Aug 2000
[en] Conditions for viewing radiological images should be adapted to the characteristics of the radiographic films as they can influence the diagnostic accuracy and detection of threshold contrasts of smaller diagnostically important structures. Since the optimal detection of small contrast details and small structures lies in the region of 1000 cd m-2, this value should be met by the viewing conditions. Data on test procedures, frequency of tests, optimum light intensities and tolerance criteria are given, based on existing recommendations. Procedures for testing the viewing conditions should be included in quality assurance programmes. (author)
Source
Moores, B.M. (Radiation Protection Service, Liverpool (UK)); Stieve, F.E. (Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen, Neuherberg (Germany, F.R.). Inst. fuer Strahlenschutz); Eriskat, H. (Commission of the European Communities, Luxembourg (Luxembourg). Directorate-General for Environment, Consumer Protection and Nuclear Safety (Radiation Protection)); Schibilla, H. (Commission of the European Communities, Brussels (Belgium). Directorate General for Science, Research and Development); British Inst. of Radiology, London (UK); Commission of the European Communities, Brussels (Belgium). Directorate General for Science, Research and Development; Commission of the European Communities, Brussels (Belgium). Directorate General for Employment, Social Affairs and Education; 165 p; ISBN 0-905749-18-9; ; 1989; p. 135-137; Workshop on technical and physical parameters for quality assurance in medical diagnostic radiology: tolerances, limiting values and appropriate measuring methods; Brussels (Belgium); 23-25 Feb 1988; Available from The British Library Document Supply Centre, Boston Spa, Wetherby, West Yorks. LS23 7BQ
; 1989; p. 135-137; Workshop on technical and physical parameters for quality assurance in medical diagnostic radiology: tolerances, limiting values and appropriate measuring methods; Brussels (Belgium); 23-25 Feb 1988; Available from The British Library Document Supply Centre, Boston Spa, Wetherby, West Yorks. LS23 7BQ
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