TOP / Publications / Journal of Light & Visual Environment (JLVE) / Volume 33 Number 2,August 2009
The Periodic Table with Regard to Atomic
Emissions
S. Kitsinelis, G. Zissis and E. Fokitis
67
Measurement of Spectral Emissivity near
Room Temperature with a Vacuum Blackbody Using a Cryogenic Refrigerator
H. Minato and Y. Ishido
70
Improvement in Durability of Red Phosphor
Encapsulated by Sol-Gel Glass for Use in White Light-Emitting Diodes
E. Kin, T. Fukuda, N. Kamata, H. Ohara, T. Yokoo and N. Kijima
82
Effects of Three Color Factors on Recognizable
Threshold of Form Perception Taking into Account Individual Differences
of Visual Abilities
Y. Akizuki and Y. Inoue
88
Study of the Potential of Natural Light
in Low and High Density Urban Environments in the Oasis City of Mendoza,
in Summer
L. Córica and A. Pattini
101
Perceived Brightness and Saturation of
Color LED Light in Dense Fog at Night Time
M. F. bin Zaini, B. A. Kurniawan, Y. Nakashima and M. Takamatsu
107
A Long-Term Energy Saving Analysis on LEDs
General Lighting in China
L. Hong
110
Trends were observed in the periodic table with regard to the emissions of the elements during the identification of promising active media for the development of low pressure discharge light sources. The strongest and most persisting emissions lines of the neutral elements, according to the existing bibliography, follow trends across a period or down a column and correlations exist between spectral ranges and the main blocks of elements.
KEYWORDS : periodic table, elements, trends, atomic emissions, neutral atoms, emission lines, visible, infrared, ultraviolet, light sources, active media, low pressure discharges, resonant transitions, atomic properties, spectroscopic data
A new type of vacuum blackbody containing both a blackbody cavity and a solid material sample was fabricated using a cryogenic refrigerator. It was to construct a highly sensitive infrared spectral-radiation measurement system using a programmable temperature control device, a Fourier transform infrared spectrophotometer, and two mercury-cadmium-telluride (MCT) detectors. Evaluation showed that the temperature of the blackbody cavity wall was accurately set within }0.2 K for 173 to 373 K and that the nonlinearity of the system response output at 173 to 373 K was within 0.8% with the proper use of the two MCT detectors. An emissivity comparison experiment using black paint (No. 1) showed that the proposed blackbody cavity method had a coincidence within 0.015 of a diffuse reflectance measuring method at 5 to 11.6 Êm. For ceramics, the emissivity temperature dependence for alumina and zirconia at 273 to 373 K was within }0.06 and }0.04, respectively.
KEYWORDS : blackbody cavity, cryogenic refrigerator, emissivity, FT-IR spectrophotometer, black paint, ceramics
Transparent glass films with homogeneously doped light emissive molecules can be prepared by using the sol-gel process. As part of our work on improving the durability of water-soluble polysilanes against UV light irradiation, we fabricated Eu(TTA)3Phen-doped sol-gel glasses and studied their optical characteristics. Using a three dimensionally dense glass network protects the Eu complex from free oxygen and water in an ambient and also improves the durability without any loss of light output. By adding the Eu(TTA)3Phen beyond the limit of solubility in a starting solution, we demonstrated that the glass encapsulation prevents oxidation of the Eu-complex and also preserves its excitation intensity at a wavelength of 400 nm.
KEYWORDS : sol-gel glass, phosphor, rare-earth complex, hybrid material
Since there is much achromatic information in actual visual environments, the effect of color on visibility must be considered when estimating the visibility of signs, objects, and lighting. The authors examined the relationship between the recognizable threshold of form perception and the three color factors (lightness, hue, and chroma) by conducting experiments using Landolt ring visual acuity test charts of 14 color conditions under three levels of background luminance. In the experiments, the visual acuity of six subjects in two age groups (young and elderly) was measured. When the test chart luminance contrast is 0.5 or above, only the lightness affects the recognizable threshold of form perception, and the chroma and hue have no effect regardless of the background luminance or individual visual acuity. Therefore, two concepts defined in our earlier studies, the gvisual acuity ratioh (to the maximum level of individual visual acuity) and grelative acuityh (incorporating individual visual acuity into the target size), hold if the luminance contrast of chromatic visual targets is 0.5 or higher. However, the concepts do not hold if the contrast is less than 0.5 due to the individual differences in color discrimination abilities.
KEYWORDS : three color factors, recognizable threshold of form perception, visual ability, color discrimination ability, individual difference
In urban geometries, the heights of building facades and the components of public spaces may constitute surfaces that modify the natural light proper to the sunny climate of the region. This study assesses the lighting potential of two urban canyons located in high and low building density areas of the oasis city of Mendoza, taking into consideration the same street orientation axis and tree species in summer. The study is conducted according to a Protocol for Natural Lighting Measurement in urban environments. As the results show, the contribution of the reflected component is reduced in the case of 30-meter wide urban canyons as the facades in the high building density area are influenced by the significant width of the streets. Furthermore, the view of the sky vault is obstructed by the trees, experiencing their maximum foliar growth in that season. On the contrary, the influence of the diffused component is, in both cases, increased.
KEYWORDS : natural light, urban environments, urban forest
Nowadays, light-emitting diodes (LED) have been widely used in real-time traffic information boards, traffic lights and vehicle lights effectively. Even though these devices are successfully used in each of their designated fields, these devices are greatly affected under bad weather conditions such as heavy rain and fog. This study determined which LED colors were affected under fog condition using LED display and artificial fog with 100µm droplet size and various densities. By using fog droplet size of 100µm and different fog densities, it is revealed that reddish yellow (RY) color was the least affected under fog influences base by saturation and brightness evaluation given by the subjects.
KEYWORDS : LED light, fog, visibility hazard, fog droplet size
Based on survey of Chinafs lighting products market and estimation of trends of LEDs technical innovation of general lighting, the paper has established a model to analyze the impacts on Chinafs future lighting market and energy efficiency potential as LEDs appear to be a next generation of general lighting source. By doing scenarios analysis, the results of this study indicated that only 1% of LEDs contribution rate to the lighting market will be realized by 2018, while up to nearly 2.5% by 2020 under the baseline scenarios; for technology-breakthrough scenarios, 1% of LEDs contribution rate will be realized by 2015, increase to 14% by 2020; while under the price-breakthrough scenarios, LEDs will constitute 1% contribution rate to the general lighting market by 2013, two years earlier in comparison, due to the decreased price, the market penetration process will speed up and by 2015 and 2020 the contribution rate of LEDs to general lighting market will increase to 9% and 69% respectively. Meanwhile, the electricity saving effects of LEDs with regard to general lighting field will show up approximately by 2013, with electricity consumption increase from over 278.4 Twh for general lighting of 2005 to 398.2 Twh in 2020 under baseline scenario; while under the technology-breakthrough scenario, the consumption for lighting of 2020 will be 344.9 Twh, under price-breakthrough scenario, the figure will drop to 313.4 Twh instead. Therefore, in 2020 there will be an energy saving possibility of 53.4 Twh with regard to the technology-breakthrough scenario; meanwhile the price-breakthrough solution in comparison with the baseline has a considerable energy saving potential over 84.8 Twh.
KEYWORDS : energy saving analysis, LEDs general lighting