摘要 :
Light is an essential element of life. The sources of light can be natural or artificial. Natural sources of light including the sun are free of charge. Artificial sources of light that are the sources made by humans cost money. T...
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Light is an essential element of life. The sources of light can be natural or artificial. Natural sources of light including the sun are free of charge. Artificial sources of light that are the sources made by humans cost money. They comprise candles, incandescent and fluorescent lamps, and light-emitting diodes (LEDs). Although the light can be provided by both types of light sources, only natural sources such as the sun ensure the perfect and healthy lighting since it has been an inherent part of the universe. This paper reviews the heterogeneous sun composition and microstructure that guarantees the perfect lighting. In addition, a light energy model is proposed. This model shows the effect of the size and therefore the number of the particles emitting the light on the corresponding spectrum and resulting light quality. This paper also investigates the light spectra for the sun, incandescent white and red lamps, fluorescent lamp, and red and yellow LEDs. This study indicates that the sun, a natural light source, produce a continuous spectrum and the best coverage of the visible colors. However, artificial light sources such as the candles, incandescent and fluorescent lamps and LEDs consisting of homogeneous materials are limited in size, light coverage, and service life. For example, their spectra show spikes and troughs and they do not cover all the visible lights properly. Finally, the effect of lamp coating and the use of eyeglasses and sunglasses were examined. The use of transparent medical eyeglasses keeps the form of the light spectrum. However, the sunglasses reduce the intensity and brightness of the visible colors and eliminate some visible colors, which is bad for clear eye vision but might be good for other applications in machines such as computers, photocopiers, televisions, and cell phones.
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The experiment was targeted to develop design strategies and methods by testing the complex interplay between the dynamics of daylight and electrical lighting in an office. The double dynamic lighting design concept is based on th...
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The experiment was targeted to develop design strategies and methods by testing the complex interplay between the dynamics of daylight and electrical lighting in an office. The double dynamic lighting design concept is based on the idea of adding task lighting, with a directionality referring to the daylight inflow and a variation on direct/diffuse lighting and respective changes in colour temperature respond to sky conditions and daylight levels. The experiment was conducted in an office space at Aalborg University in Copenhagen from September to December 2019. Four participants moved in and worked in the office with four-week periods of respective standard static lighting as a baseline, and dynamic lighting. In a parallel mixed method approach with interviews and questionnaires, the dynamic lighting was compared to the baseline and to a control group. The results indicate that the dynamic lighting periods had a positive effect on visual comfort, perceived atmosphere and work engagement. The studies helped to develop the definition of five dynamic light settings. Seasonal changes, time of day, dynamic sunscreens and individual needs for task lighting can be implemented in future field experiments as additional dynamic parameters to meet individual needs and circadian potentials for double dynamic light.
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Outdoor lighting fixtures are used to illuminate surrounding streets, parking lots, walkways, and the landscape surrounding many buildings. Examples of these light fixtures are cobra head streetlights, Acorns and Colonials. These ...
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Outdoor lighting fixtures are used to illuminate surrounding streets, parking lots, walkways, and the landscape surrounding many buildings. Examples of these light fixtures are cobra head streetlights, Acorns and Colonials. These streetlights are typically designed to achieve illumination levels required by published design standards such as minimum illuminance levels on parking as well as pedestrian walkways. The light from poles close to buildings often spills off onto building facades. This influences the illumination of the facade and impacts on light trespass ordinances of some municipalities. This paper develops a method for studying such an effect and outlines ways to minimize the effect of outdoor lighting on facade illumination without compromising parking lot and walkway illumination. A comparison is made between various types of area and road light fixtures.
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Basic information on the problems of converting the electrical energy into the light energy has been given in the paper. Parameters, which can influence the light parameters, have been pointed out. Measurement results of ripple fa...
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Basic information on the problems of converting the electrical energy into the light energy has been given in the paper. Parameters, which can influence the light parameters, have been pointed out. Measurement results of ripple factor versus colour temperature of fluorescent lamps supplied with AC voltage of various frequencies have been presented. On the base of the obtained results, conclusions concerning the ripple depth versus colour temperature and supplying voltage frequency have been formulated.
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The last century can be divided into three periodes: at the turn of the 20~(th) century the periode of _"industrialization", after the second world war the periode of _"reconstruction" and at the end of the century the periode con...
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The last century can be divided into three periodes: at the turn of the 20~(th) century the periode of _"industrialization", after the second world war the periode of _"reconstruction" and at the end of the century the periode connected with the _"environment". By studying the changes that have taken place in light source development, lighting research and lighting application during these three periodes, we can detect trends that may determine in which direction lighting will change in the future. These changes are discussed and illustrated and possible directions for the future are given.
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Although light trap can be used to control pest populations, they can also kill the natural enemies of pests. Scleroderma guani (Hymenoptera: Bethylidae) is a parasitoid of a bark-weevil Pissodes punctatus (Coleoptera: Curculionid...
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Although light trap can be used to control pest populations, they can also kill the natural enemies of pests. Scleroderma guani (Hymenoptera: Bethylidae) is a parasitoid of a bark-weevil Pissodes punctatus (Coleoptera: Curculionidae). To understand the phototactic behavior of S. guani, we investigated its diurnal and nocturnal behavior, then examined its phototactic response to nine monochromatic lights and to five intensities of the two most attractive lights. Our results showed that S. guani is most active during the day, while remain still in a dark room or at night. S. guani showed a positive response both to a broad spectrum of monochromatic light and total light (natural light), which implies a broad sensitivity to the light spectrum. S. guani was most sensitive to blue (450 nm) and green (549 nm) lights, suggesting its visual system composed of blue and green receptors. S. guani was least sensitive to ultraviolet (340 nm) light, which may be caused by long-term mass rearing and propagating under artificial conditions. Furthermore, low intensities elicited a positive phototactic response, while high intensities showed a decreased trend under both blue and green lights. Thus, S. guani is a phototactic insect which shows preferences for light in both color and intensity. This study suggests that light trap can only be utilized to control the adult P. punctatus during and after its peak emergence, due to the overlap in the spectral sensitivity of both pest and parasitoid adults.
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The paper presents the authors’concept of an adaptive road lighting that is concurrent with vehicles moving on roads.The lighting system is based on luminaires with light emitting diodes.The authors describe the operation of the ...
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The paper presents the authors’concept of an adaptive road lighting that is concurrent with vehicles moving on roads.The lighting system is based on luminaires with light emitting diodes.The authors describe the operation of the adaptive road lighting system and point out benefits and limitations of the solution.The theoretical considerations are supported by an analysis of the installed and working system that was implemented at Bozeny street in Poznan,Poland.The system was also evaluated by the residents living near the street.
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Abstract Human skin is not only affected by ultraviolet radiation but also by visible light wavelengths emitted by sunlight, electronic devices, and light emitting diodes. Similar to the ultraviolet radiation, visible light has be...
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Abstract Human skin is not only affected by ultraviolet radiation but also by visible light wavelengths emitted by sunlight, electronic devices, and light emitting diodes. Similar to the ultraviolet radiation, visible light has been implicated in photoaging. In this review, the effects of blue light, yellow light, red light, and broad visible light are discussed in relation with photoaging. Different visible light wavelengths likely contribute beneficial and deleterious effects on photoaging by way of interaction with specific photoreceptors, ROS production, and other photon‐mediated reactions. Further in vivo studies are needed to determine the mechanism and action spectrum of photoaging in humans, as well as optimal photoprotection with coverage against visible light wavelengths.
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We previously reported that a near-null magnetic field suppressed Arabidopsis flowering in white light, which might be related to the function modification of cryptochrome (CRY). To further demonstrate that the effect of near-null...
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We previously reported that a near-null magnetic field suppressed Arabidopsis flowering in white light, which might be related to the function modification of cryptochrome (CRY). To further demonstrate that the effect of near-null magnetic field on Arabidopsis flowering is associated with CRY, Arabidopsis wild type and CRY mutant plants were grown in the near-null magnetic field under blue or red light with different light cycle and photosynthetic photon flux density. We found that Arabidopsis flowering was significantly suppressed by near-null magnetic field in blue light with lower intensity (10 mu mol/m(2)/s) and shorter cycle (12h period: 6h light/6h dark). However, flowering time of CRY1/CRY2 mutants did not show any difference between plants grown in near-null magnetic field and in local geomagnetic field under detected light conditions. In red light, no significant difference was shown in Arabidopsis flowering between plants in near-null magnetic field and local geomagnetic field under detected light cycles and intensities. These results suggest that changes of blue light cycle and intensity alter the effect of near-null magnetic field on Arabidopsis flowering, which is mediated by CRY. Bioelectromagnetics. 36:476-479, 2015. (c) 2015 Wiley Periodicals, Inc.
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ABSTRACT Human perception and vision have evolved in response to dynamic daylight, a combination of radiation from direct sunlight and diffuse skylight, which has created a flow of variations in light, in terms of direct:diffuse d...
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ABSTRACT Human perception and vision have evolved in response to dynamic daylight, a combination of radiation from direct sunlight and diffuse skylight, which has created a flow of variations in light, in terms of direct:diffuse distribution, intensities and spectrum. This study investigates the qualities of the flow of light in an office after adding ceiling-mounted spotlights (32° tilt angle) to traditional diffuse ceiling panels. The intention is to create a flow of task light – a light-zone at each work-plane – complementing the directionality of the natural daylight inflow from the windows. An experiment was carried out in an office, in two parts. Four ratios of direct:diffuse light were tested by 30 people. Then one ratio was tested in five combinations of high, neutral and low color temperatures by 15 people in two daylight situations: overcast and clear sky. The visual light quality and perceived atmosphere of the office environment was tested through questionnaires, reaction cards and semi-structured interviews. The direct flow of light is recommended to be more than 15% of the total illuminance at the work-plane to provide the distinct visual appearance of modeling and a cozier atmosphere, which is preferable for socializing, and less than 45% to avoid glare and high contrast for visual tasks. Direct warm and diffuse cool lighting were perceived as the most natural but were not always preferred. There is an indication of slight preference for cooler ambient lighting in clear sky situations and warmer ambient lighting in overcast situations. Especially the preference in relation to sky conditions needs to be further investigated. A field study will implement these findings in a double dynamic lighting concept responding to daylight level and sky character. Strong individual preferences for combinations of color temperatures was identified, this open up new research areas for personalized flows of light in future dynamic lighting designs.
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