| Records |
| Author |
Kocifaj, M. |
| Title |
Towards a Comprehensive City Emission Function (CCEF) |
Type |
Journal Article |
| Year |
2018 |
Publication |
Journal of Quantitative Spectroscopy and Radiative Transfer |
Abbreviated Journal |
JQSRT |
| Volume |
205 |
Issue |
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Pages |
253-266 |
| Keywords |
Lighting; Skyglow |
| Abstract |
The comprehensive city emission function (CCEF) is developed for a heterogeneous light-emitting or blocking urban environments, embracing any combination of input parameters that characterize linear dimensions in the system (size and distances between buildings or luminaires), properties of light-emitting elements (such as luminous building façades and street lighting), ground reflectance and total uplight-fraction, all of these defined for an arbitrarily sized 2D area. The analytical formula obtained is not restricted to a single model class as it can capture any specific light-emission feature for wide range of cities. The CCEF method is numerically fast in contrast to what can be expected of other probabilistic approaches that rely on repeated random sampling. Hence the present solution has great potential in light-pollution modeling and can be included in larger numerical models. Our theoretical findings promise great progress in light-pollution modeling as this is the first time an analytical solution to city emission function (CEF) has been developed that depends on statistical mean size and height of city buildings, inter-building separation, prevailing heights of light fixtures, lighting density, and other factors such as e.g. luminaire light output and light distribution, including the amount of uplight, and representative city size. The model is validated for sensitivity and specificity pertinent to combinations of input parameters in order to test its behavior under various conditions, including those that can occur in complex urban environments. It is demonstrated that the solution model succeeds in reproducing a light emission peak at some elevated zenith angles and is consistent with reduced rather than enhanced emission in directions nearly parallel to the ground. |
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ScienceDirect |
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| Language |
English |
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English |
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| Call Number |
LoNNe @ kyba @ |
Serial |
1757 |
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| Author |
Clanton, N.; Gibbons, R.; Garcia, J.; Barber, M. |
| Title |
Seattle LED Adaptive Lighting Study |
Type |
Report |
| Year |
2014 |
Publication |
Northwest Energy Efficiency Alliance |
Abbreviated Journal |
NEEA |
| Volume |
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Issue |
E14-286 |
Pages |
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| Keywords |
Public Safety; Lighting; Planning; Vision |
| Abstract |
The Northwest Energy Efficiency Alliance (NEEA) and the City of Seattle partnered to evaluate the future of solid state street lighting in the Pacific Northwest with a two-night demonstration in Seattle's Ballard neighborhood in March 2012. The study evaluates the effectiveness of LED streetlights on nighttime driver object detection visibility as function of light source spectral distribution (color temperature in degrees K) and light distribution. Clanton & Associates and VTTI also evaluated adaptive lighting (tuning of streetlights during periods of reduced vehicular and pedestrian activity) at three levels: one hundred percent of full light output, fifty percent of full light output, and twenty-five percent of full light output. The study, led by Clanton & Associates, Continuum Industries, and the VTTI, built upon previous visual performance studies conducted in Anchorage, Alaska; San Diego, California; and San Jose, California. The use of LED technology for city street lighting is becoming more widespread. While these lights are primarily touted for their energy efficiency, the combination of LEDs with advanced control technology, changes to lighting criteria, and a better understanding of human mesopic (low light level) visibility creates an enormous potential for energy savings and improved motorist and pedestrian visibility and safety. Data from these tests support the following statements: LED luminaires with a correlated color temperature of 4100K provide the highest detection distance, including statistically significantly better detection distance when compared to HPS luminaires of higher wattage. The non-uniformity of the lighting on the roadway surface provides a visibility enhancement and greater contrast for visibility. Contrast of objects, both positive and negative, is a better indicator of visibility than is average luminance level. Dimming the LED luminaires to fifty percent of IES RP-8 levels did not significantly reduce object detection distance in dry pavement conditions. Participants perceived dimming of sidewalks as less acceptable than dimming to the same level on the roadway. Asymmetric lighting did reduce glare and performed similarly to the symmetric lighting at the same color temperature (4100K). |
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English |
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LoNNe @ kyba @ |
Serial |
1763 |
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| Author |
Tosini, G.; Ferguson, I.; Tubota, K. |
| Title |
Effects of blue light on the circadian system and eye physiology |
Type |
Journal Article |
| Year |
2016 |
Publication |
Molecular Vision |
Abbreviated Journal |
Mol Vis |
| Volume |
22 |
Issue |
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Pages |
61-72 |
| Keywords |
Vision; blue light; Circadian Rhythm; eye; physiology |
| Abstract |
Light-emitting diodes (LEDs) have been used to provide illumination in industrial and commercial environments. LEDs are also used in TVs, computers, smart phones, and tablets. Although the light emitted by most LEDs appears white, LEDs have peak emission in the blue light range (400–490 nm). The accumulating experimental evidence has indicated that exposure to blue light can affect many physiologic functions, and it can be used to treat circadian and sleep dysfunctions. However, blue light can also induce photoreceptor damage. Thus, it is important to consider the spectral output of LED-based light sources to minimize the danger that may be associated with blue light exposure. In this review, we summarize the current knowledge of the effects of blue light on the regulation of physiologic functions and the possible effects of blue light exposure on ocular health. |
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Department of Pharmacology and Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA |
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NCBI |
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English |
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English |
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1090-0535 |
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no |
| Call Number |
IDA @ john @ |
Serial |
2216 |
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| Author |
S Fotios, J Uttley |
| Title |
Illuminance required to detect a pavement obstacle of critical size |
Type |
Journal Article |
| Year |
2018 |
Publication |
Lighting Research & Technology |
Abbreviated Journal |
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| Volume |
50 |
Issue |
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Pages |
390-404 |
| Keywords |
Vision; Lighting |
| Abstract |
This paper investigates the illuminance needed to detect trip hazards for pedestrians walking after dark. In previous work, it was assumed that the critical obstacle height is 25 mm: further review of accident data and foot clearance data suggests instead that 10 mm is the critical height. Eye tracking records suggest a tendency for obstacles to be detected approximately 3.4 m ahead. Interpretation of obstacle detection data suggests horizontal photopic illuminances of up to 0.9 lux are required for peripheral detection of a 10 mm obstacle 3.4 m ahead, according to the scotopic/photopic ratio of the lighting and the age of the observer. |
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no |
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LoNNe @ kyba @ |
Serial |
1765 |
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| Author |
Fotios, S., Price, T |
| Title |
Road lighting and accidents: Why lighting is not the only answer |
Type |
Journal Article |
| Year |
2017 |
Publication |
Lighting Journal |
Abbreviated Journal |
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| Volume |
82 |
Issue |
5 |
Pages |
22-26 |
| Keywords |
Lighting; Public Safety |
| Abstract |
Tony Price and Steve Fotios point out that while road lighting can be a significant counter measure to accidents, and that higher levels might help, the presence of road lighting does not guarantee all accidents will be avoided. |
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no |
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LoNNe @ kyba @ |
Serial |
1767 |
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