toggle visibility Search & Display Options

Select All    Deselect All
 |   | 
Details
   print
  Records Links (up)
Author Galadí-Enríquez, D. url  doi
openurl 
  Title Beyond CCT: The spectral index system as a tool for the objective, quantitative characterization of lamps Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal JQSRT  
  Volume 206 Issue Pages 399-408  
  Keywords Lighting  
  Abstract Correlated color temperature (CCT) is a semi-quantitative system that roughly describes the spectra of lamps. This parameter gives the temperature (measured in kelvins) of the black body that would show the hue more similar to that of the light emitted by the lamp. Modern lamps for indoor and outdoor lighting display many spectral energy distributions, most of them extremely different to those of black bodies, what makes CCT to be far from a perfect descriptor from the physical point of view. The spectral index system presented in this work provides an accurate, objective, quantitative procedure to characterize the spectral properties of lamps, with just a few numbers. The system is an adaptation to lighting technology of the classical procedures of multi-band astronomical photometry with wide and intermediate-band filters. We describe the basic concepts and we apply the system to a representative set of lamps of many kinds. The results lead to interesting, sometimes surprising conclusions. The spectral index system is extremely easy to implement from the spectral data that are routinely measured at laboratories. Thus, including this kind of computations in the standard protocols for the certification of lamps will be really straightforward, and will enrich the technical description of lighting devices.  
  Address  
  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 GFZ @ kyba @ Serial 1835  
Permanent link to this record
 

 
Author Petržala, J. url  doi
openurl 
  Title Feasibility of inverse problem solution for determination of city emission function from night sky radiance measurements Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 213 Issue Pages 86-94  
  Keywords Skyglow  
  Abstract The knowledge of the emission function of a city is crucial for simulation of sky glow in its vicinity. The indirect methods to achieve this function from radiances measured over a part of the sky have been recently developed. In principle, such methods represent an ill-posed inverse problem. This paper deals with the theoretical feasibility study of various approaches to solving of given inverse problem. Particularly, it means testing of fitness of various stabilizing functionals within the Tikhonov’s regularization. Further, the L-curve and generalized cross validation methods were investigated as indicators of an optimal regularization parameter. At first, we created the theoretical model for calculation of a sky spectral radiance in the form of a functional of an emission spectral radiance. Consequently, all the mentioned approaches were examined in numerical experiments with synthetical data generated for the fictitious city and loaded by random errors. The results demonstrate that the second order Tikhonov’s regularization method together with regularization parameter choice by the L-curve maximum curvature criterion provide solutions which are in good agreement with the supposed model emission functions.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language 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 GFZ @ kyba @ Serial 1868  
Permanent link to this record
 

 
Author Aubé, M.; Simoneau, A. url  doi
openurl 
  Title New features to the night sky radiance model illumina: Hyperspectral support, improved obstacles and cloud reflection Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 211 Issue Pages 25-34  
  Keywords  
  Abstract Illumina is one of the most physically detailed artificial night sky brightness model to date. It has been in continuous development since 2005 [1]. In 2016–17, many improvements were made to the Illumina code including an overhead cloud scheme, an improved blocking scheme for subgrid obstacles (trees and buildings), and most importantly, a full hyperspectral modeling approach. Code optimization resulted in significant reduction in execution time enabling users to run the model on standard personal computers for some applications.

After describing the new schemes introduced in the model, we give some examples of applications for a peri-urban and a rural site both located inside the International Dark Sky reserve of Mont-Mégantic (QC, Canada).
 
  Address Cégep de Sherbrooke, 475, rue du Cégep, Sherbrooke, Québec J1E 4K1, Canada; martin.aube(at)cegepsherbrooke.qc.ca  
  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 1818  
Permanent link to this record
 

 
Author Baddiley, C. url  doi
openurl 
  Title Light pollution modelling, and measurements at Malvern Hills AONB, of county conversion to blue rich LEDs Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 219 Issue Pages 142-173  
  Keywords Skyglow  
  Abstract The introduction of blue rich colour, Correlated-Colour-Temperature (CCT) 6000K road lighting could increase skyglow significantly compared with CCT 3000K types, if the blue content reaches the sky.

Highways England have a policy for lighting specification on motorways advised by the author's work. This is a categorised environmental impact point system of summed brightness as a function of angle from vertically down to the cut off angle; but with no CCT limitation.

Modelling was done for Malvern-Hills Area-of-Outstanding-Natural-Beauty (MHAONB), for the nighttime environmental impact of the LED replacement of Low-Pressure-Sodium throughout Herefordshire. The study was extended to include High-Pressure-Sodium and to LEDs at several CCTs, for the same Photopic ground illuminance.

Dark-Sky-Survey geographic location results for the MHAONB (2012) are described. Near-Zenith sky brightness photometry became continuous from 2016 at 2 minute intervals in all weathers, not just clear nights, with a networked calibrated Unihedron Lensed Sky Quality Meter (LSQM). Samples were also taken of all-sky camera images, corrected for vignetting and near-Zenith calibrated with the LSQM, to study weather effects, Milky Way contribution, and Herefordshire lighting conversion to blue-rich LEDs (2013-15), compared with the less converted Severn valley direction.

Time-plots and histogram analysis showed a small reduction in brightness (2012-2018), 0.1 mag.arcsec−2. Most variation is from increased sampling of distant cloud cover effects. Mist or low cloud on the horizon obscures light sources beyond reducing local skyglow, while high cloud reflects, increasing clear sky brightness. The Milky Way is critically 20% above background. Darkest periods near Zenith reach 21.1 mag.arcsec−2, to 21.2 after rain or surrounding low-cloud or poor-visibility. Clear-sky brightness decreases into early hours (∼0.03 mag.arcsec−2/hr); dimming effects were not seen.

The Zenith brightness is still set by distant cities, while towards the horizon, commercial and private uncontrolled non-directional LED lighting is increasing, negating the improvements in road lighting.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language 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 GFZ @ kyba @ Serial 1914  
Permanent link to this record
 

 
Author Ges, X.; Bará, S.; García-Gil, M.; Zamorano, J.; Ribas, S.J.; Masana, E. url  doi
openurl 
  Title Light pollution offshore: Zenithal sky glow measurements in the mediterranean coastal waters Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 210 Issue Pages 91-100  
  Keywords  
  Abstract Light pollution is a worldwide phenomenon whose consequences for the natural environment and the human health are being intensively studied nowadays. Most published studies address issues related to light pollution inland. Coastal waters, however, are spaces of high environmental interest, due to their biodiversity richness and their economical significance. The elevated population density in coastal regions is accompanied by correspondingly large emissions of artificial light at night, whose role as an environmental stressor is increasingly being recognized. Characterizing the light pollution levels in coastal waters is a necessary step for protecting these areas. At the same time, the marine surface environment provides a stage free from obstacles for measuring the dependence of the skyglow on the distance to the light polluting sources, and validating (or rejecting) atmospheric light propagation models. In this work we present a proof-of-concept of a gimbal measurement system that can be used for zenithal skyglow measurements on board both small boats and large vessels under actual navigation conditions. We report the results obtained in the summer of 2016 along two measurement routes in the Mediterranean waters offshore Barcelona, travelling 9 and 31.7 km away from the coast. The atmospheric conditions in both routes were different from the ones assumed for the calculation of recently published models of the anthropogenic sky brightness. They were closer in the first route, whose results approach better the theoretical predictions. The results obtained in the second route, conducted under a clearer atmosphere, showed systematic differences that can be traced back to two expected phenomena, which are a consequence of the smaller aerosol content: the reduction of the anthropogenic sky glow at short distances from the sources, and the slower decay rate of brightness with distance, which gives rise to a relative excess of brightness at large distances from the coastline.  
  Address Departament de Projectes d'Enginyeria i la Construcció, Universitat Politècnica de Catalunya/BARCELONATECH, Barcelona, Spain; salva.bara(at)usc.es  
  Corporate Author Thesis  
  Publisher Elsevierier 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 1816  
Permanent link to this record
Select All    Deselect All
 |   | 
Details
   print

Save Citations:
Export Records: