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Author  |
Babadi, S.; Ramirez-Inguiez, R.; Boutaleb, T.; Mallick, T. | ||||
| Title | Producing uniform illumination within a rectangular area by using a nonimaging optic | Type | Journal Article | ||
| Year | 2018 | Publication | Applied Optics | Abbreviated Journal | Appl. Opt. |
| Volume | 57 | Issue | 31 | Pages | 9357 |
| Keywords | Lighting | ||||
| Abstract | This paper proposes a new design method to create a novel optical element to generate uniform illumination within a rectangular area. Based on this model, an illuminated area is irradiated by two sets of rays; the first one irradiates the target plane after refraction from the top section of the lens, and the second one irradiates from the reflection at the side profile of the lens and then from refraction at the top part of the lens. The results show that a uniformity of over 90% can be achieved. | ||||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1559-128X | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | GFZ @ kyba @ | Serial | 2046 | ||
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| Author |
Baddiley, C. | ||||
| 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. |
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| 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 |
Bagan, H.; Borjigin, H.; Yamagata, Y. | ||||
| Title | Assessing nighttime lights for mapping the urban areas of 50 cities across the globe | Type | Journal Article | ||
| Year | 2018 | Publication | Environment and Planning B: Urban Analytics and City Science | Abbreviated Journal | Environment and Planning B: Urban Analytics and City Science |
| Volume | Issue | Pages | 2399808317752926 | ||
| Keywords | Remote Sensing | ||||
| Abstract | Nighttime data from the Defense Meteorological Satellite Program Operational Linescan System have been widely used to map urban/built-up areas (hereafter referred to as “built-up area”), but to date there has not been a geographically comprehensive evaluation of the effectiveness of using nighttime lights data to map urban areas. We created accurate, convenient, and scalable grid cells based on Defense Meteorological Satellite Program/Operational Linescan System nighttime light pixels. We then calculated the density of Landsat-derived built-up areas within each grid cell. We explored the relationship between Defense Meteorological Satellite Program/Operational Linescan System nighttime lights data and the density of built-up areas to assess the utility of nighttime lights for mapping urban areas in 50 cities across the globe. We found that the brightness of nighttime lights was only in moderate agreement with the density of built-up areas; moreover, correlations between nighttime lights and Landsat-derived built-up areas were weak. Even in relatively sparsely populated urban regions (where the density of the built-up area is less than 20%), the highest correlation coefficient (R2) was only 0.4. Furthermore, nighttime lights showed lighted areas that extended beyond the area of large cities, and nighttime lights reduced the area of small cities. The results suggest that it is difficult to use the regression model to calibrate the Defense Meteorological Satellite Program/Operational Linescan System nighttime lights to fit urban built up areas. | ||||
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| ISSN | 2399-8083 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | LoNNe @ kyba @; GFZ @ kyba @ | Serial | 1795 | ||
| Permanent link to this record | |||||
| Author |
Bará, S.; Escofet, J. | ||||
| 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 | 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 | |
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0022-4073 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | IDA @ john @ | Serial | 2163 | ||
| Permanent link to this record | |||||
| Author |
Bará, S.; Lima, R.C. | ||||
| Title | Photons without borders: quantifying light pollution transfer between territories | Type | Journal Article | ||
| Year | 2018 | Publication | International Journal of Sustainable Lighting | Abbreviated Journal | |
| Volume | 20 | Issue | 2 | Pages | 51-61 |
| Keywords | Skyglow | ||||
| Abstract | The light pollution levels experienced at any given site generally depend on a wide number of artificial light sources distributed throughout the surrounding territory. Since photons can travel long distances before being scattered by the atmosphere, any effective proposal for reducing local light pollution levels needs an accurate assessment of the relative weight of all intervening light sources, including those located tens or even hundreds of km away. In this paper we describe several ways of quantifying and visualizing these relative weights. Particular emphasis is made on the aggregate contribution of the municipalities, which are -in many regions of the world- the administrative bodies primarily responsible for the planning and maintenance of public outdoor lighting systems. | ||||
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| Notes | Approved | no | |||
| Call Number | NC @ ehyde3 @ | Serial | 2066 | ||
| Permanent link to this record | |||||