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Author Li, Fusheng; Chen, Yuming; Liu, Yang; Chen, Dahua
Title Comparative in Situ Study of LEDs and HPS in Road Lighting Type Journal Article
Year 2012 Publication LEUKOS: The Journal of the Illuminating Engineering Society of North America Abbreviated Journal Leukos
Volume 8 Issue 3 Pages 205-214
Keywords Roadway lighting, visibility, LED, high-pressure sodium; LED lighting; HPS, STV, achromatic target, colored target
Abstract The effect of spectrum on the visibility of roadway lighting targets was investigated. The experiment focused on the relation between average visibility ratings and small target visibility (STV) under installations that employed LED and HPS light sources. Achromatic targets were more visible under LEDs illumination conditions than under HPS illumination conditions. The results also suggest that the visibility of colored objects on the road was better under LEDs illumination conditions in comparison to HPS. The results cannot be generalized to all LED light sources, but are likely indicative of LEDs with similar spectral power distributions (SPDs). Relative visibility under source types with different SPDs, and which provide different luminance distributions, should merit consideration when selecting a light source for roadway lighting.
Address Department of Illuminating Engineering & Light Sources, School of Information Science and Engineering, Fudan University, China
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Notes Approved no
Call Number IDA @ john @ Serial 337
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Author Sweater-Hickcox, K.; Narendran, N.; Bullough, J.; Freyssinier, J.
Title Effect of different coloured luminous surrounds on LED discomfort glare perception Type Journal Article
Year 2013 Publication Lighting Research and Technology Abbreviated Journal Lighting Research and Technology
Volume 45 Issue 4 Pages 464-475
Keywords perception; subjective; LED; LED lighting; spectral power distribution; SPD
Abstract Recently, there has been increased interest in energy-efficient lighting as energy resources become higher in demand. Anecdotal evidence suggests that certain populations believe light-emitting diodes (LED) produce more glare than traditional technologies. This may be due to a number of factors such as spectral power distribution (SPD), source luminance, or beam intensity distribution. A study was conducted to assess the effect of different SPDs on the perception of discomfort glare from an LED source. For the range of conditions evaluated, the presence of any luminous surround significantly reduced the perception of discomfort glare from the LED array. The blue luminous surround reduced discomfort glare perception significantly less than the white or the yellow luminous surrounds. The implications for solid-state lighting systems are discussed.
Address Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA
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ISSN 1477-1535 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial 338
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Author Kostic, A.; Kremic, M.; Djokic, L.; Kostic, M.
Title Light-emitting diodes in street and roadway lighting – a case study involving mesopic effects Type Journal Article
Year 2013 Publication Lighting Research and Technology Abbreviated Journal Lighting Research and Technology
Volume 45 Issue 2 Pages 217-229
Keywords LED; LED lighting; mesopic; street lighting; outdoor lighting; roadway lighting
Abstract The paper considers the justification for the application of light-emitting diode (LED) technology to urban lighting. The results suggest that LEDs are convenient for architectural lighting and deserve to be considered for use in ambient lighting. The recently developed Commission Internationale de l’Eclairage (CIE) mesopic system enabled the inclusion of mesopic effects into a comprehensive techno-economic analysis, which dealt with efficiency, maintenance and financial aspects of the use of LEDs in street and roadway lighting. It is concluded that the average energy savings when using LED instead of high-pressure sodium (HPS) luminaires amount to 19–26% for single-sided, staggered and opposite layouts, although they are frequently negligible if mesopic effects are not included. The total costs of the LED lighting solutions, even including mesopic effects, are 1.36 to 6.44 times higher than those of the comparable HPS lighting solutions. Therefore, LEDs are questionable for street and roadway lighting.
Address Faculty of Architecture, University of Belgrade, Belgrade, Serbia
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ISSN 1477-1535 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial 339
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Author Vetter, C.; Juda, M.; Lang, D.; Wojtysiak, A.; Roenneberg, T.
Title Blue-enriched office light competes with natural light as a zeitgeber Type Journal Article
Year 2011 Publication Scandinavian Journal of Work, Environment & Health Abbreviated Journal Scand J Work Environ Health
Volume 37 Issue 5 Pages 437-445
Keywords *Circadian Rhythm; *Color; Humans; *Lighting; *Occupational Health; Sleep; Wakefulness; blue light; circadian disruption; Circadian rhythm; sleep
Abstract OBJECTIVES: Circadian regulation of human physiology and behavior (eg, body temperature or sleep-timing), depends on the “zeitgeber” light that synchronizes them to the 24-hour day. This study investigated the effect of changing light temperature at the workplace from 4000 Kelvin (K) to 8000 K on sleep-wake and activity-rest behavior. METHODS: An experimental group (N=27) that experienced the light change was compared with a non-intervention group (N=27) that remained in the 4000 K environment throughout the 5-week study period (14 January to 17 February). Sleep logs and actimetry continuously assessed sleep-wake behavior and activity patterns. RESULTS: Over the study period, the timing of sleep and activity on free days steadily advanced parallel to the seasonal progression of sunrise in the non-intervention group. In contrast, the temporal pattern of sleep and activity in the experimental group remained associated with the constant onset of work. CONCLUSION: The results suggest that artificial blue-enriched light competes with natural light as a zeitgeber. While subjects working under the warmer light (4000 K) appear to entrain (or synchronize) to natural dawn, the subjects who were exposed to blue-enriched (8000 K) light appear to entrain to office hours. The results confirm that light is the dominant zeitgeber for the human clock and that its efficacy depends on spectral composition. The results also indicate that blue-enriched artificial light is a potent zeitgeber that has to be used with diligence.
Address Institute for Medical Psychology, Centre of Chronobiology, Ludwig-Maximilians-Universitat, Munich, Germany
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ISSN 0355-3140 ISBN Medium
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Notes PMID:21246176 Approved no
Call Number IDA @ john @ Serial 350
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Author Lin, Y.; Liu, Y.; Sun, Y.; Zhu, X.; Lai, J.; Heynderickx, I.
Title Model predicting discomfort glare caused by LED road lights Type Journal Article
Year 2014 Publication Optics Express Abbreviated Journal Opt. Express
Volume 22 Issue 15 Pages 18056
Keywords LED; LED lighting; glare; road safety; traffic
Abstract To model discomfort glare from LED road lighting, the effect of four key variables on perceived glare was explored. These variables were: the average glare source luminance (Lg), the background luminance (Lb), the solid angle of the glare source from the perspective of the viewer; and the angle between the glare source and the line of sight. Based on these four variables 72 different light conditions were simulated in a scaled experimental set-up. Participants were requested to judge the perceived discomfort glare of these light conditions using the deBoer rating scale. All four variables and some of their interactions had indeed a significant effect on the deBoer rating. Based on these findings, we developed a model, and tested its general applicability in various verification experiments, including laboratory conditions as well as real road conditions. This verification proved the validity of the model with a correlation between measured and predicted values as high as 0.87 and a residual deviation of about 1 unit on the deBoer rating scale. These results filled the gap in estimating discomfort glare of LED road lighting and clarified similarities of and differences in discomfort glare between LED and traditional light sources.
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ISSN 1094-4087 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 351
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