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Author Bará, S. url  doi
openurl 
  Title Characterizing the zenithal night sky brightness in large territories: how many samples per square kilometre are needed? Type Journal Article
  Year 2017 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal  
  Volume 473 Issue 3 Pages 4164-4173  
  Keywords Instrumentation; atmospheric effects; light pollution; numerical methods; photometry  
  Abstract A recurring question arises when trying to characterize, by means of measurements or theoretical calculations, the zenithal night sky brightness throughout a large territory: how many samples per square kilometre are needed? The optimum sampling distance should allow reconstructing, with sufficient accuracy, the continuous zenithal brightness map across the whole region, whilst at the same time avoiding unnecessary and redundant oversampling. This paper attempts to provide some tentative answers to this issue, using two complementary tools: the luminance structure function and the Nyquist–Shannon spatial sampling theorem. The analysis of several regions of the world, based on the data from the New world atlas of artificial night sky brightness, suggests that, as a rule of thumb, about one measurement per square kilometre could be sufficient for determining the zenithal night sky brightness of artificial origin at any point in a region to within ±0.1 magV arcsec–2 (in the root-mean-square sense) of its true value in the Johnson–Cousins V band. The exact reconstruction of the zenithal night sky brightness maps from samples taken at the Nyquist rate seems to be considerably more demanding.  
  Address (up) 1Departamento de Física Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es  
  Corporate Author Thesis  
  Publisher Oxford Academic Place of Publication Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0035-8711 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number IDA @ john @ Serial 2164  
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Author Bará, S.; Escofet, J. url  doi
openurl 
  Title On lamps, walls, and eyes: The spectral radiance field and the evaluation of light pollution indoors Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal J of Quant Spect and Rad Trans  
  Volume 205 Issue Pages 267-277  
  Keywords Instrumentation; Light pollution; Artificial light at night; Light field; Radiance field; Radiometry; Photometry  
  Abstract Light plays a key role in the regulation of different physiological processes, through several visual and non-visual retinal phototransduction channels whose basic features are being unveiled by recent research. The growing body of evidence on the significance of these effects has sparked a renewed interest in the determination of the light field at the entrance pupil of the eye in indoor spaces. Since photic interactions are strongly wavelength-dependent, a significant effort is being devoted to assess the relative merits of the spectra of the different types of light sources available for use at home and in the workplace. The spectral content of the light reaching the observer eyes in indoor spaces, however, does not depend exclusively on the sources: it is partially modulated by the spectral reflectance of the walls and surrounding surfaces, through the multiple reflections of the light beams along all possible paths from the source to the observer. This modulation can modify significantly the non-visual photic inputs that would be produced by the lamps alone, and opens the way for controlling—to a certain extent—the subject's exposure to different regions of the optical spectrum. In this work we evaluate the expected magnitude of this effect and we show that, for factorizable sources, the spectral modulation can be conveniently described in terms of a set of effective filter-like functions that provide useful insights for lighting design and light pollution assessment. The radiance field also provides a suitable bridge between indoor and outdoor light pollution studies.  
  Address (up) Área de Óptica, Departamento de Física Aplicada, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-4073 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number IDA @ john @ Serial 2163  
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Author Bará, S. url  doi
openurl 
  Title Variations on a classical theme: On the formal relationship between magnitudes per square arcsecond and luminance Type Journal Article
  Year 2017 Publication International Journal of Sustainable Lighting Abbreviated Journal Intl J of Sustainable Lighting  
  Volume 19 Issue 2 Pages 77  
  Keywords Instrumentation; skyglow; luminance; magnitude; sky brigthness; photometry  
  Abstract The formal link between magnitudes per square arcsecond and luminance is discussed in this paper. Directly related to the human visual system, luminance is defined in terms of the spectral radiance of the source, weighted by the CIE V(l) luminous efficiency function, and scaled by the 683 lm/W luminous efficacy constant. In consequence, any exact and spectrum-independent relationship between luminance and magnitudes per square arcsecond requires that the last ones be measured precisely in the CIE V(l) band. The luminance value corresponding to mVC=0 (zero-point of the CIE V(l) magnitude scale) depends on the reference source chosen for the definition of the magnitude system. Using absolute AB magnitudes, the zero point luminance of the CIE V(l) photometric band is 10.96 x 104 cd·m-2.  
  Address (up) Departamento de Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2586-1247 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number IDA @ john @ Serial 2162  
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Author Fiorentin, P.; Boscaro, F. url  doi
openurl 
  Title A method for measuring the light output of video advertising reproduced by LED billboards Type Journal Article
  Year 2019 Publication Measurement Abbreviated Journal Measurement  
  Volume 138 Issue Pages 25-33  
  Keywords Lighting; Energy; Instrumentation; Planning; Light-emitting diode displays; Photometry; Video recording; Image analysis; CCD image sensors; Luminance; Glare  
  Abstract Improving knowledge of the light output of digital billboards is important to better assess their effect on driver distraction when they are installed along roads. In this work the emission of an LED based billboard is measured when playing advertising video-clips. In particular the average and the maximum values of the luminance are evaluated. The same video-clips are also analyzed when shown on an LCD monitor, aiming at separating the variability of the videos and of the playing device. The results allow to evaluate an utilization factor of the billboard: the videos have an average luminance around 11% and a peak luminance of 35% of the maximum luminance obtainable from the billboard. The power consumption of the billboard is measured, aside the photometric analysis. The luminance of the device are found linearly dependent on both the power and the effective current absorbed by the device from the grid, with a discrepancy within 6%. It could be a useful information for billboard manufacturers to qualify their product when they do not own photometric instruments.  
  Address (up) Department of Industrial Engineering, University of Padova, Padova, Italy; pietro.fiorentin(at)unipd.it  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0263-2241 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2214  
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Author Rybnikova, N.A.; Portnov, B.A. url  doi
openurl 
  Title Using light-at-night (LAN) satellite data for identifying clusters of economic activities in Europe Type Journal Article
  Year 2015 Publication Letters in Spatial and Resource Sciences Abbreviated Journal Lett. Spatial & Resource Sci.  
  Volume 8 Issue 3 Pages 307–334  
  Keywords Remote Sensing; Economic activities; Clusters; Satellite photometry; Light-at-night; Europe; Nomenclature of Territorial Units for Statistics; C13; C38; O52; Economics  
  Abstract Enterprises organized in clusters are often efficient in stimulating urban development, productivity and profit outflows. Identifying the clusters of economic activities thus becomes an important step in devising regional development policies, aimed at the formation of clusters of economic activities in geographic areas in which this objective is desirable. However, a major problem with the identification of such clusters stems from limited reporting by individual countries and administrative entities on the regional distribution of specific economic activities, especially for small regional subdivisions. In this study, we test a possibility that missing data on geographic concentrations of economic activities in the European NUTS3 regions can be reconstructed using light-at-night satellite measurements, and that such reconstructed data can then be used for cluster identification. The matter is that light-at-night, captured by satellite sensors, is characterized by different intensity, depending on its source—production facilities, services, etc. As a result, light-at-night can become a marker of different types of economic activities, a hypothesis that the present study confirms. In particular, as the present analysis indicates, average light-at-night intensities emitted from NUTS3 regions help to explain up to 94 % variance in the areal density of several types of economic activities, performing especially well for professional, scientific and technical services (R^2=0.742−0.939), public administration (R^2=0.642−0.934), as well as for arts, entertainment and recreation (R^2=0.718−0.934). As a result, clusters of these economic activities can be identified using light-at-night data, thus helping to supplement missing information and assist regional analysis.  
  Address (up) Department of Natural Resources and Environmental Management, Faculty of Management, University of Haifa, 31805, Mt. Carmel, Israel; Portnov@research.haifa.ac.il  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number IDA @ john @ Serial 1148  
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