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A review on smart application of supplemental lighting in greenhouse fruiting vegetable production
摘要： Different spectra of light trigger different plant growth processes. Therefore, the optimum light spectrum for various plant physiological and growth processes may be different. For greenhouse fruiting vegetables, such as tomatoes, it is important to optimize light spectrum to promote canopy growth to increase light interception during the early stage of plant growth. Once the plants reach full canopy, the focus should be moved to optimizing vertical light distribution because most greenhouse fruiting vegetables are tall crops and the growth processes along the vertical profile are different; most of the canopy growth occurs in the top and middle canopy while fruit growth occurs in the middle and bottom canopy. Because the fruit, not the leaf, is the economic product, the optimized light spectral composition should enhance leaf carbon export and translocation to fruit to improve fruit yield and quality. Therefore, a research project was initiated in 2013 to identify proper light spectral composition and vertical distribution regimes for greenhouse fruiting vegetable production. Different overhead light sources (high-pressure sodium light with or without far-red light-emitting diode (LED) light, plasma light and different spectral compositions of LEDs) and several intra-canopy spectral compositions provided by LEDs were evaluated over four winters on tomatoes, mini-cucumbers and sweet peppers. The effects of light spectrum on whole-plant net carbon exchange and leaf carbon export using 14C-isotype tracing were also investigated. The vertical light regimes resulted in significant differences in leaf photosynthetic rate, leaf size, fruit yield and fruit quality in greenhouse tomatoes, mini-cucumbers and sweet peppers. Proper vertical light regimes were identified for hybrid light systems (overhead high intensity discharge light + intra-canopy LEDs) and for pure LED light systems (overhead + intra-canopy LEDs). This review clearly demonstrates that optimized vertical light regimes can be developed for improving both plant growth and fruit yield and quality in year-round greenhouse fruiting vegetable production.
关键词： far-red light,Solanum lycopersicum,Capsicum annuum,Cucumis sativus,light quality,vertical light spectral distribution,temperature,LED,lighting,spectral composition
更新于2025-09-23 15:22:29
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Influence of a Light Source Installed in a Luminaire of Opal Sphere Type on the Effect of Light Pollution
摘要： The article presents the results of the studies concerning the influence of a light source installed in luminaire of opal sphere type on the light pollution effect of the night sky. It is known from literature reports that the effect of light pollution is influenced by the spectral distribution of light. Although the influence of the spectral distribution has been widely studied from different perspectives, there is still a need to study this phenomenon—for example, from the point of view of the spectral reflection properties of the ground, on which the lanterns are installed. Hence, the above-mentioned aspect was considered in the authors’ investigations. The luminaire considered has been equipped with 20 different light sources, including the latest generation of lamps (light-emitting diodes, LEDs) as well as the conventional ones. With respect to these light sources, the measurements of light distribution and spectral distribution of emitted radiation of the luminaire were performed. Having these measurement data, the simulations were carried out using the DIALux software, and the calculations were made using the specially prepared calculation tool. On the basis of the results obtained in this way this was stated that the type of light source installed in the luminaire has a significant effect on the sky glow. An important factor affecting light pollution is not only the value of the luminous flux emitted upward but also the spectral characteristics of the emitted radiation, the impact of which is most noticeable. The conclusions from the studies indicate the next steps in the analysis of the light pollution effect. These steps will be focused on extended analysis of LEDs as modern and developed light sources.
关键词： light pollution,light color,lighting,light source,spectral distribution,sky glow
更新于2025-09-23 15:19:57
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || Solar Radiation
摘要： The sun’s structure and characteristics determine the nature of the energy it radiates into space. The first major topic in this chapter concerns the characteristics of this energy outside the earth’s atmosphere, its intensity, and its spectral distribution. We will be concerned primarily with radiation in a wavelength range of 0.25 to 3.0 μm, the portion of the electromagnetic radiation that includes most of the energy radiated by the sun. The second major topic in this chapter is solar geometry, that is, the position of the sun in the sky, the direction in which beam radiation is incident on surfaces of various orientations, and shading. The third topic is extraterrestrial radiation on a horizontal surface, which represents the theoretical upper limit of solar radiation available at the earth’s surface. An understanding of the nature of extraterrestrial radiation, the effects of orientation of a receiving surface, and the theoretically possible radiation at the earth’s surface is important in understanding and using solar radiation data, the subject of Chapter 2.
关键词： solar radiation,extraterrestrial radiation,diffuse radiation,solar geometry,spectral distribution,solar constant,beam radiation
更新于2025-09-16 10:30:52
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Optical Smoothing with Reduced FM-to-AM Conversion in High-Power Lasers Using Spectral Distribution
摘要： High-power energetic nanosecond lasers, such as the Laser Mégajoule, require optical smoothing techniques to make their focal spots as homogeneous as possible. This strongly reduces parametric instabilities that occur during laser-plasma interaction, such as stimulated Brillouin scattering. Smoothing by spectral dispersion is one of the most-used techniques. It requires spectral broadening through phase modulation. However, because of propagation impairments, part of the phase modulation is converted into unwanted intensity modulation that induces laser nonlinearities and optical damage. This is called “FM-to-AM conversion.” Taking advantage of the architecture of the Laser Mégajoule, for which each “beam” (quadruplet) is split into four sub-beams, we show that the spectral broadening can be distributed on the sub-beams, reducing FM-to-AM conversion from 30% to 10% while maintaining smoothing performance for mitigation of stimulated Brillouin scattering.
关键词： FM-to-AM conversion,stimulated Brillouin scattering,optical smoothing,spectral distribution,high-power lasers
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 4th International Symposium on Wireless Systems within the International Conferences on Intelligent Data Acquisition and Advanced Computing Systems (IDAACS-SWS) - Lviv, Ukraine (2018.9.20-2018.9.21)] 2018 IEEE 4th International Symposium on Wireless Systems within the International Conferences on Intelligent Data Acquisition and Advanced Computing Systems (IDAACS-SWS) - Adaptation Video Signal to Spectral Distribution of Light Source
摘要： The current advances in video technology require the improvement of the nodes of the cut-off path, which is why in this work attention is focused on the terminal devices. The results of modeling on separate variants are presented and the possibility of scaling them for universal use in systems of video transmission is considered. The algorithm of the choice reference spectral distribution of illumination sources by given color coordinates is presented. It is proposed to select the spectral distribution of the source of illumination from the overall image scene. It is suggested to use a metrological set for calculating the magnitude of the influence of the source of illumination on the quality of color reproduction. The algorithm was developed to exclude the influence of the source of light on the quality of the transmitted video.
关键词： quality estimation,rendering,spectral distribution,color estimation methods,technologies,adaptive metrological support
更新于2025-09-11 14:15:04