Journal articles on the topic 'LED lighting diodes'
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1
Koksal, Nezihe, Meral Incesu, and Ahmet Teke. "Supplemental LED lighting increases pansy growth." Horticultura Brasileira 33, no. 4 (September 18, 2015): 428–33. http://dx.doi.org/10.1590/s0102-053620150000400004.
Abstract:
ABSTRACT: Pansy (Viola cornuta) is a facultative long-day plant that flowers from October until March in Turkey. During the winter months, low light levels can limit plant growth and development. Light emitting diodes (LEDs) can provide supplemental lighting in greenhouses which produce same light intensity with less energy than conventional incandescent lighting. Light emitting diode technologies have enabled affordable and efficient light systems to be installed in greenhouses and plastic tunnels in the field. In this experiment we evaluated the effects of supplemental red-orange LED lightening on the growth and development of pansy cv. Blue Blotch grown in plastic tunnels. The energy, which LEDs are to consume, was provided through a solar panel system with the aim of drawing attention to the cleanliness of solar energy source. Five hours of supplement LED lighting was applied after dusk starting from November to February. Pansy growth and development parameters were compared with non-light supplied control plants. Supplemental LED lighting significantly increased plant biomass weight, flower number and leaves number at the rate of 52%, 72%, and 47%, respectively. Moreover, LED lighting increased plant growth rate (0.109 and 0.306 g of fresh weight), compared with the no light control. LED lighting, however, had no effect on length of stems, number of branches and the diameter of flowers. Thus, this study indicated that pansies are light limited during the winter months and supplemental LED lighting can significantly increase pansy growth and development.
2
Aladov, Andrey V., Alexander L. Zakgeim, Julia V. Semyashkina, and Anton E. Chernyakov. "Dynamically Controlled LED Luminaire for Contrast Visualisation of Biological Tissues During Surgical Procedures." Light & Engineering, no. 06-2021 (December 2021): 144–50. http://dx.doi.org/10.33383/2021-059.
Abstract:
The article reviews the main theoretical, engineering and technological, circuit-engineering and software aspects of development of a dynamically controlled luminaire based on light emitting diodes for contrast visualisation of biological tissues during surgical procedures. The design concept of such surgical luminaire is proposed, which combines high-quality white lighting and coloured accent lighting increasing the contrast of visualisation of particular tissues and borders between them. The calculation model of the luminaire optical system allows maximising the level of illumination and uniformity of illuminance and colour of the surgical area. The software of the luminaire allows to independently modifying intensity of radiation of six coloured light emitting diodes with blue (460 nm), turquoise (505 nm), green (530 nm), green-yellow (550 nm), orange (590 nm) and red (630 nm) light colours for synthesis of coloured lighting of virtually any chromaticity. The level of general lighting by means of phosphor light emitting diodes can also be varied within a wide range. Chromaticity and level of lighting are adjusted by means of pulse-duration modulation of light emitting diode current and the light parameters of the luminaire are controlled by a remote computer via a radio channel. This medical luminaire is primarily designed for lighting during surgical procedures and it can also be used for visual diagnostics based on the colour of analysed tissues.
3
Pakhomova, E. E., and V. P. Gorkin. "LED lighting of automobiles and tractors." Izvestiya MGTU MAMI 7, no. 1-1 (January 10, 2013): 153–58. http://dx.doi.org/10.17816/2074-0530-68275.
Abstract:
The article considers the possibilities of application of high-brightness semiconductor light-emitting diodes in lighting systems of automobiles and tractors. There are shown the main parameters of LEDs and circuit diagrams of their connection.
4
SHUR, MICHAEL, and ARTURAS ŽUKAUSKAS. "LIGHT EMITTING DIODES: TOWARD SMART LIGHTING." International Journal of High Speed Electronics and Systems 20, no. 02 (June 2011): 229–45. http://dx.doi.org/10.1142/s012915641100657x.
Abstract:
We review the history and state-of-the-art of light emitting diode (LED). Unique properties of LEDs– high efficiency, long life time, flexibility in obtaining customized spectral power distribution, fast modulation rate, compact form factor, ability to generate radiation with wavelengths outside the visible range (infrared and ultraviolet, including deep ultraviolet) enable multiple applications for signage, display, general lighting, biology, medicine, agriculture, communications, industrial controls, security, and transportation. Many of emerging LED applications will be in "smart lighting", which are applications that are not possible or difficult to achieve using more traditional lighting sources.
5
Sun, Ching-Cherng, Shih-Hsin Ma, and Quang-Khoi Nguyen. "Advanced LED Solid-State Lighting Optics." Crystals 10, no. 9 (August 27, 2020): 758. http://dx.doi.org/10.3390/cryst10090758.
Abstract:
Light-emitting diodes (LEDs) have been intensively studied for white-light lighting since their luminous efficacy exceeds 50 lm/W. Currently, the luminous efficacy of an LED light tube/bulb is almost above 100 lm/W. LED solid-state lighting (SSL) has unequivocally become the major light source in general lighting. The fact of high efficiency and other advantages of LED SSL is enough to penetrate all lighting scenarios. However, what people demand from new-generation lighting is not only in energy efficiency but also in lighting quality. Thus, how to make the lighting more user friendly is one of the important issues, and, here, optics is the key point. For making a collection with the discussions of the novel optical design in enhancing lighting efficiency in a more uniform illumination pattern, in higher sharpness for special lighting, in a higher signal-to-noise ratio for communication, in more functions for new applications, etc., this Special Issue of “Advanced LED Solid-State Lighting Optics” focuses on advanced applications in all aspects.
6
Kolesnyk, A. "Optical System for Led Luminaire." Metrology and instruments, no. 4 (September 7, 2019): 62–67. http://dx.doi.org/10.33955/2307-2180(4)2019.62-67.
Abstract:
Lighting devices are an important element of a large number of technical systems, including road, living, industrial lighting, lighting systems of vehicles. It is known that the light instrument must fulfill two basic lighting tasks: to redistribute the light source of light source in the right way and to limit its dazzling effect. The introduction of light-emitting diodes (LEDs) for lighting necessitated a completely new quality in the construction of luminaires. The different production technology required new methods and designing tools. It also challenged designers with new problems to solve. LEDs are light sources emitting in one hemisphere, which requires a special approach to designing an LED lighting unit. However, for the illumination of premises with high spans or streets, roads such a light distribution is not suitable. For luminaires with solid-state light sources, other materials and new technology must be used; moreover, light distribution needs to be formed using different methods.
This paper presents the design process of a LED luminaire from concept to implementation, exemplified by road lighting, and describes the methods and procedures used by the designer. Also, technological problems influencing the quality of the above lighting are addressed. Optical systems for LEDs are considered. The peculiarities of the use of secondary optical elements in the form of lenses for purpose of obtaining different diagrams of the spatial distribution of light intensity of light-emitting diodes are analyzed. Features and problems of calculation of secondary optical systems are considered. Massive collimators do not have to be elements that focus a narrow beam of light. They are able to form a beam in accordance with any accepted distribution that is appropriate for a given application. They are also able to form a beam in a specific way that is required for outdoor lighting luminaires. The stages of a project for designing a road luminaire require the application of the knowledge and experience gained in various research projects. The design methods described in this paper have been developed designing activity and are also to be used successfully in lighting production.
7
Morrow, Robert C. "LED Lighting in Horticulture." HortScience 43, no. 7 (December 2008): 1947–50. http://dx.doi.org/10.21273/hortsci.43.7.1947.
Abstract:
Solid-state lighting based on the use of light-emitting diodes (LEDs) is potentially one of the biggest advancements in horticultural lighting in decades. LEDs can play a variety of roles in horticultural lighting, including use in controlled environment research, lighting for tissue culture, and supplemental and photoperiod lighting for greenhouses. LED lighting systems have several unique advantages over existing horticultural lighting, including the ability to control spectral composition, the ability to produce very high light levels with low radiant heat output when cooled properly, and the ability to maintain useful light output for years without replacement. LEDs are the first light source to have the capability of true spectral composition control, allowing wavelengths to be matched to plant photoreceptors to provide more optimal production and to influence plant morphology and composition. Because they are solid-state devices, LEDs are easily integrated into digital control systems, facilitating special lighting programs such as “daily light integral” lighting and sunrise and sunset simulations. LEDs are safer to operate than current lamps because they do not have glass envelopes or high touch temperatures, and they do not contain mercury. The first sustained work with LEDs as a source of plant lighting occurred in the mid-1980s to support the development of new lighting systems to be used in plant growth systems designed for research on the space shuttle and space station. These systems progressed from simple red-only LED arrays using the limited components available at the time to high-density, multicolor LED chip-on-board devices. As light output increases while device costs decrease, LEDs continue to move toward becoming economically feasible for even large-scale horticultural lighting applications.
8
Hytönen, T., P. Pinho, M. Rantanen, S. Kariluoto, A. Lampi, M. Edelmann, K. Joensuu, et al. "Effects of LED light spectra on lettuce growth and nutritional composition." Lighting Research & Technology 50, no. 6 (March 28, 2017): 880–93. http://dx.doi.org/10.1177/1477153517701300.
Abstract:
Year-round greenhouse production in northern latitudes depends on the use of artificial lighting. Light emitting diodes provide a promising means to save energy during cultivation as well as to modify the light spectrum to regulate the growth and quality of the crop. We compared the effects of light emitting diode lighting with different spectral compositions on the growth, development and nutritional quality of lettuce ( Lactuca sativa L. ‘Frillice’). We show that warm-white and warm-white supplemented with blue spectra provide equal growth and product quality compared to conventional high-pressure sodium lighting in the absence and presence of daylight. Our data indicate that for biomass accumulation, the far-red component in the light spectrum is more critical than green light or the red/blue ratio. Furthermore, we demonstrate that a red + blue spectrum increases the concentration of several vitamins in lettuce. However, biomass accumulation using this spectrum was insufficient when daylight was excluded.
9
Chen, William, Ka Wai Eric Cheng, and Jianwei Shao. "Circuit Topology Analysis for LED Lighting and its Formulation Development." Energies 12, no. 21 (November 4, 2019): 4203. http://dx.doi.org/10.3390/en12214203.
Abstract:
Light emitted diode (LED) is becoming more popular in the illumination field, and the design of LED lighting is generally made to provide illumination at lower power usage, helping save energy. A power electronic converter is needed to provide the power conversion for these LEDs to meet high efficiency, reduce components, and have low voltage ripple magnitude. The power supply for LED is revisited in this paper. The LEDs connected in series with diode, transistor, or inductor paths are examined. The formulation for each of the cases is described, including the classical converters of buck, boost, buck–boost, and Ćuk. The circuit reductions of the classic circuit, circuit without the capacitor, and without a freewheeling diode are studied. Using LED to replace freewheeling diodes is proposed for circuit component reduction. General equations for different connection paths have been developed. The efficiency and output ripple amplitude of the proposed power converters are investigated. Analytical study shows that the efficiency of proposed circuits can be high and voltage ripple magnitude of proposed circuits can be low. The results show that the proposed circuit topologies can be easily adapted to design LED lighting, which can meet the criteria of high efficiency, minimum components, and low-voltage ripple magnitude at the same time.
10
Liu, Hailiang, Jiade Cheng, and Asnidar Hanim Yusuf. "Design of Light Emitting Diodes (LEDs) Lighting System and Its Application in Garden Landscape Decoration." Journal of Nanoelectronics and Optoelectronics 15, no. 6 (June 1, 2020): 734–42. http://dx.doi.org/10.1166/jno.2020.2793.
Abstract:
Light Emitting Diode (LED) is widely used in garden landscape decoration because of its small size, low power, concentrated light, and the capability of showing more vivid colors. While designing the LED lighting system, considering that a single Advanced RISC Machine (ARM)-based control system cannot achieve large-scale LED display, and a single Field Programmable Gate Array (FPGA)-based control system cannot control the lighting system well, an LED system with the combination of ARM processor-FPGA is proposed. In this system, the ARM processor is used as the major control component. The Linux system realizes remote monitoring and intelligent management of image data. In addition, FPGA is used for LED data output. The lighting system consists of a major control node and a lighting node. The nodes are connected in parallel through a chain network. The major control node uses an ARM Cortex processor and is equipped with a Linux operating system. The lighting node uses ARM + FPGA hardware architecture. During the experiments, the LED lighting system is tested first. The results show that the reading and writing speed is fast. The LED display screen meets the lighting requirements. This LED lighting system is used for night lighting of garden landscapes. During the brightness test, the brightness of lighting objects and the background is used as research objects. Experiments have proved that the ratio of the lighting object brightness to the background brightness between (Yu, M. and Li, X., 2012. A little current k-factor method for measuring junction temperature of aviation lighting power led. Guangxue Jishu/Optical Technique, 38(3), pp.371–375; Monas, A., Verma, A., Gawari, A. and Paswan, R. S., 2016. Portable network monitor using arm processor. Procedia Computer Science, 92, pp.493–497.) is suitable for night lighting of garden landscape decoration, which will not bring discomfort to people who enjoy night scenery.
11
Reese, SB, K. Horowitz, M. Mann, and T. Remo. "Research note: LED lighting – A global enterprise." Lighting Research & Technology 52, no. 7 (January 29, 2020): 849–55. http://dx.doi.org/10.1177/1477153520901757.
Abstract:
There is considerable focus on technology manufacturing locations and the value in funding innovation when upstream products are not manufactured within a domestic economy. Light-emitting diodes (LEDs) are such an upstream product. Here, we evaluate the value added along the supply chain of luminaires, a product that utilizes LEDs, using bottom-up cost modelling. Coupling the results with analysis of shipping cost and time, this analysis examines how advances in LEDs can incentivize LED luminaire adoption leading to the potential for significant domestic manufacturing effects even if the upstream products are produced in other economies.
12
Vairavan, Rajendaran, Zaliman Sauli, and Vithyacharan Retnasamy. "Operating Temperature Analysis of LED with Cylindrical Cu Slug." Applied Mechanics and Materials 487 (January 2014): 145–48. http://dx.doi.org/10.4028/www.scientific.net/amm.487.145.
Abstract:
High power light emitting diodes is the new era of lighting due to momentous supremacy in terms of lighting efficacy over traditional lighting systems. The reliability of LED is dependent on its junction temperature. This study confers on the thermal and stress characterization of LED chip with copper cylindrical heat slug through simulation method. The simulation characterization was carried out with Ansys version 11 at ambient temperature of 25°C under natural convection condition. The LED package was powered with input powers of 0.1 W, 0.5 W and 1W .Results indicated that input power influences the junction temperature and stress of LED chip.
13
Otasowie, P. O., and O. Siloko. "Design and Implementation of a Power Failure Home Lighting System Using LED Arrays." Advanced Materials Research 824 (September 2013): 108–13. http://dx.doi.org/10.4028/www.scientific.net/amr.824.108.
Abstract:
This paper is on the design and implementation of a power failure lighting system using light emitting diodes (LED) arrays. The aim of this work is to design and implement a lighting system that can provide low power at home when there is power failure. The lighting system was achieved by the design of the: Power Supply Unit, Charging Unit, Change Over Switch, Battery Level Indicator, LED arrays.The power failure home lighting system was designed and implemented in a three bedroom flat apartment in Benin City when there was power failure. The total lighting points in the house consume a total power of 160 watts which was very low compared to energy saving (i.e. CFL) lamp (312 watts) and incandescent bulbs (480 to 740 watts). The designed power failure home lighting system performed satisfactorily.
14
Legentil, Paul, Fabrice Leroux, Sandrine Therias, Damien Boyer, and Geneviève Chadeyron. "Sulforhodamine B-LDH composite as a rare-earth-free red-emitting phosphor for LED lighting." Journal of Materials Chemistry C 8, no. 34 (2020): 11906–15. http://dx.doi.org/10.1039/d0tc02802a.
15
Humphreys, Colin J. "Solid-State Lighting." MRS Bulletin 33, no. 4 (April 2008): 459–70. http://dx.doi.org/10.1557/mrs2008.91.
Abstract:
AbstractElectricity generation is the main source of energy-related greenhouse gas emissions and lighting uses one-fifth of its output. Solid-state lighting using light-emitting diodes (LEDs) is poised to reduce this value by at least 50%, so that lighting will then use less than one-tenth of all electricity generated. LED lighting will provide reductions of at least 10% in fuel consumption and carbon dioxide emissions from power stations within the next 5–10 years. Even greater reductions are likely on a 10–20-year timescale.
16
Wang, Li, Haoran Zhang, Xiaohua Zhou, Yingliang Liu, and Bingfu Lei. "A dual-emitting core–shell carbon dot–silica–phosphor composite for LED plant grow light." RSC Advances 7, no. 27 (2017): 16662–67. http://dx.doi.org/10.1039/c7ra00227k.
17
Luo, Li Jun, Fen Fen Hu, Zheng Liang Wang, and Ying Jie Zhang. "Spectroscopic Properties of New Yellow-Emitting Phosphor for LED Solid-State Lighting." Applied Mechanics and Materials 368-370 (August 2013): 799–804. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.799.
Abstract:
New yellow phosphors, Eu2+ and Zn2+ co-activated Sr3Al2O5Cl2, were prepared by solid state reaction technique, and their photoluminescent properties were investigated. Sr2.6Al2O5Cl2:0.20Eu2+, 0.20Zn2+ shows broadened the excitation band in near UV range and intense yellow emission under 400 nm light excitation by introducing into Zn2+. The single yellow light-emitting diodes were fabricated by combining InGaN-chips with Sr2.8Al2O5Cl2: 0.20Eu2+ and Sr2.6Al2O5Cl2:0.20Eu2+, 0.20Zn2+, intense yellow light can be observed by naked eyes from the yellow LEDs. Hence, the phosphor Sr2.6Al2O5Cl2:0.20Eu2+, 0.20Zn2+ may be applied in fabrication of phosphor-converted light-emitting diodes.
18
Žukauskas, Artūras, Michael S. Shur, and Remis Gaska. "Light-Emitting Diodes: Progress in Solid-State Lighting." MRS Bulletin 26, no. 10 (October 2001): 764–69. http://dx.doi.org/10.1557/mrs2001.203.
Abstract:
Until the beginning of the 19th century, flame produced by combustion was the only source of artificial light. Since then, physical phenomena other than pyroluminescence have been used to produce light. Limelight (incandescence of calcium oxide heated by the flame from an oxyhydrogen blowpipe), gas mantles (candoluminescence of gas-flame-heated rare-earth oxides), and the electrical Jablochkoff candle (an early type of carbon-arc lamp) were among the important milestones that led to modern lighting technology. In the 21st century, most of the residential lighting worldwide is provided by tungsten incandescent lamps. Compact fluorescent lamps are also actively promoted because of their higher performance—a broader spectrum for higher-quality white light and elimination of 100–120-Hz flickering, for example. Most work environments employ fluorescent tubes for general lighting, and street lighting is dominated by sodium lamps. Lighting consumes ∼2000 TWh of energy annually, about 21% of the global consumption of electricity. However, during the past 20 years, none of the conventional lighting technologies has exhibited a significant improvement in efficiency. The drive to save lighting energy and reduce its negative environmental impact (i.e., carbon emissions and the disposal of mercury contained in discharge lamps) stimulates the search for new, efficient sources of light.
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Gajc-Wolska, Janina, Katarzyna Kowalczyk, Arkadiusz Przybysz, Małgorzata Mirgos, and Paweł Orliński. "Photosynthetic Efficiency and Yield of Cucumber (Cucumis sativus L.) Grown under HPS and LED Lighting in Autumn–Winter Cultivation." Plants 10, no. 10 (September 28, 2021): 2042. http://dx.doi.org/10.3390/plants10102042.
Abstract:
The objective of this study was to evaluate the effect of the supplemental lighting of cucumber with sodium pressure lamps (HPSs) and light-emitting diodes (LEDs) on photosynthetic efficiency and yield in autumn–winter cultivation. Cucumber plants of the ‘Svyatogor’ F1 midi-cucumber parthenocarpic type cultivar were grown on mineral wool mats in three compartments, differing only in the type of light, i.e., (1) HPS top lighting (HPS) in the first compartment, (2) HPS top lighting and LED panel interlighting (HPS + LED) in the second compartment and (3) LED top lighting and inter-row LED panels (LED) in the third compartment. The photosynthetically active radiation was the same in each compartment. The study showed that the highest commercial yields of cucumber could be achieved under LED light (top and inter-row). The chlorophyll content in the leaf blade of younger leaves was higher in plants under LED lighting. This type of lighting also had a positive effect on the gas exchange of plants (net carbon assimilation, stomatal conductance, transpiration). LED and HPS + LED lighting increased the chlorophyll a fluorescence parameters, such as Fs, Fm’ and vitality index (PI), in both younger and older leaves, which also increased the fruit yield in the tested combinations.
20
Martín, Beatriz, Héctor Pérez, and Miguel Ferrer. "Light-Emitting Diodes (LED): A Promising Street Light System to Reduce the Attraction to Light of Insects." Diversity 13, no. 2 (February 19, 2021): 89. http://dx.doi.org/10.3390/d13020089.
Abstract:
Currently, there is a demand for more energy-efficient lighting sources, however, light emitted by different lighting systems differs in primary properties such as intensity, propagation direction, and wavelength spectrum, among others, and these properties may affect insect light attraction. Despite the energetic benefits of light-emitting diodes (LED) as street light systems, their ecological impacts on insects have not yet been tested on a wide range of taxa. Using an experimental approach, we showed that LED street lights lead to a reduction in the total number of insects captured with light traps in a wide range of families. Coleoptera and Lepidoptera orders were the most sensitive groups to ecological light pollution in the study area. We suggest that LED was the least attractive light system for most of the affected groups both because of its very little emitted short-wavelength light and because of its lower light intensity. We expect that the more and more widespread use of LED lights as a measure to reduce economic costs of outdoor lighting should lead to a lower attraction to street lights in most of the affected insect taxa and to diminish the negative impacts of artificial light attraction on the ecosystems.
21
Adam. "DALI LED Driver Control System for Lighting Operations Based on Raspberry Pi and Kernel Modules." Electronics 8, no. 9 (September 12, 2019): 1021. http://dx.doi.org/10.3390/electronics8091021.
Abstract:
Light emitting diodes (LEDs) as an efficient low-consumption lighting technology are being used increasingly in many applications. The move to LED lighting is also changing the way the lighting control systems are designed. Currently, most electronic ballasts and other digital lighting devices implement the Digital Addressable Lighting Interface (DALI) standard. This paper presents a low-cost, low-power effective DALI LED driver controller, based on open-source Raspberry Pi3 microcontroller prototyping platform. The control software is developed as a Linux kernel module under UBUNTU 18.04.2 LTS patched with PREEMPT_RT (Preemptive Real-time) for real-time processing. This dynamically loaded kernel module performs all the processing, communication and control operations of the Raspberry Pi3-based DALI controller with the DALI LED driver and LED luminaire. Software applications written in C and Python were developed for performance testing purposes. The experimental results showed that the proposed system could efficiently and effectively manage DALI LED drivers and perform lighting operations (e.g. dimming). The system can be used for a variety of purposes from personal lighting control needs and experimental research in control of electronic ballasts and other control gears, devices and sensors, to advanced requirements in professional buildings, including energy management, lighting maintenance and usage.
22
Schulte-Römer, Nona, Josiane Meier, Max Söding, and Etta Dannemann. "The LED Paradox: How Light Pollution Challenges Experts to Reconsider Sustainable Lighting." Sustainability 11, no. 21 (November 4, 2019): 6160. http://dx.doi.org/10.3390/su11216160.
Abstract:
In the 21st century, the notion of “sustainable lighting” is closely associated with LED technology. In the past ten years, municipalities and private light users worldwide have installed light-emitting diodes in urban spaces and public streets to save energy. Yet an increasing body of interdisciplinary research suggests that supposedly sustainable LED installations are in fact unsustainable, because they increase light pollution. Paradoxically, blue-rich cool-white LED lighting, which is the most energy-efficient, also appears to be the most ecologically unfriendly. Biologists, physicians and ecologists warn that blue-rich LED light disturbs the circadian day-and-night rhythm of living organisms, including humans, with potential negative health effects on individual species and whole ecosystems. Can the paradox be solved? This paper explores this question based on our transdisciplinary research project Light Pollution—A Global Discussion. It reveals how light pollution experts and lighting professionals see the challenges and potential of LED lighting from their different viewpoints. This expert feedback shows that “sustainable LED lighting” goes far beyond energy efficiency as it raises complex design issues that imply stakeholder negotiation. It also suggests that the LED paradox may be solved in context, but hardly in principle.
23
TAMULAITIS, GINTAUTAS. "LEDs IN DEVELOPING WORLD." International Journal of High Speed Electronics and Systems 20, no. 02 (June 2011): 343–58. http://dx.doi.org/10.1142/s0129156411006635.
Abstract:
Every fifth inhabitant of our planet has no access to electric lighting. Most of them are poor people living in remote areas of developing countries. Recent progress in solid-state lighting technologies offers good opportunities to develop, commercialize and introduce off-grid lighting systems based on application of white light emitting diodes (WLEDs) in combination with photovoltaic solar panels, wind generators or tiny hydro power plants. Though strongly dependent on the mainstream progress in implementation of LEDs for general lighting, application of this technology in developing world has specific challengers, difficulties and even advantages. Lighting technology the developing world is up to leapfrog from splinters and kerosene wick lamps directly to LED lamps leaving incandescent and fluorescence lamps behind. Achievements and problems, history and future of implementation of solid-state lighting in remote villages of developing counties are discussed in this chapter.
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Massa, Gioia D., Hyeon-Hye Kim, Raymond M. Wheeler, and Cary A. Mitchell. "Plant Productivity in Response to LED Lighting." HortScience 43, no. 7 (December 2008): 1951–56. http://dx.doi.org/10.21273/hortsci.43.7.1951.
Abstract:
Light-emitting diodes (LEDs) have tremendous potential as supplemental or sole-source lighting systems for crop production both on and off earth. Their small size, durability, long operating lifetime, wavelength specificity, relatively cool emitting surfaces, and linear photon output with electrical input current make these solid-state light sources ideal for use in plant lighting designs. Because the output waveband of LEDs (single color, nonphosphor-coated) is much narrower than that of traditional sources of electric lighting used for plant growth, one challenge in designing an optimum plant lighting system is to determine wavelengths essential for specific crops. Work at NASA's Kennedy Space Center has focused on the proportion of blue light required for normal plant growth as well as the optimum wavelength of red and the red/far-red ratio. The addition of green wavelengths for improved plant growth as well as for visual monitoring of plant status has been addressed. Like with other light sources, spectral quality of LEDs can have dramatic effects on crop anatomy and morphology as well as nutrient uptake and pathogen development. Work at Purdue University has focused on geometry of light delivery to improve energy use efficiency of a crop lighting system. Additionally, foliar intumescence developing in the absence of ultraviolet light or other less understood stimuli could become a serious limitation for some crops lighted solely by narrow-band LEDs. Ways to prevent this condition are being investigated. Potential LED benefits to the controlled environment agriculture industry are numerous and more work needs to be done to position horticulture at the forefront of this promising technology.
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Burynin, Dmitriy, and Aleksandr Smirnov. "Overview of the Grow Lights Used in Greenhouses and Plant Factories." Elektrotekhnologii i elektrooborudovanie v APK 1, no. 42 (January 2021): 105–13. http://dx.doi.org/10.22314/2658-4859-2020-67-2-105-113.
Abstract:
Phyto-emitters for plants are used to grow vegetables in cold climates all year round and to increase the yield in places with insufficient solar radiation. In recent years, the crop lighting industry has been undergoing innovative changes. Thanks to light-emitting diodes, the market for plant lighting is growing rapidly. (Research purpose) The research purpose is in studying the market of lighting for crop production, analyzing the advantages and disadvantages of various phyto-emitters for growing plants in closed agroecosystems. (Materials and methods) The article presents a review on the state of the vegetable growing sector in the closed ground in Russia, as well as works on phyto-emitters for growing plants. The collected materials on phyto-emitters were classified and analyzed, and the prospects for their implementation were proposed. Authors used the methods of a systematic approach. (Results and discussion) The possibilities of light-emitting diodes and arc sodium tube lamps were studied. The device of phyto-emitters on top of the canopy of high vegetable crops leads to an uneven distribution of light, LED irradiators in the aisle leads to an increase in the amount of harvest. It was found that LED lamps are more effective for shelving plant cultivation. In cold climates, plant factories can be more rational than greenhouses with additional illumination under LED lighting. LED irradiators for crop production were classified according to the type of lamp. The article lists the most popular types of phyto-emitters based on LEDs. LED lighting systems designed to provide a sufficient level of photosynthetically active radiation are ideal for growing plants. (Conclusions) The selection of the spectrum of photosynthetically active radiation for plants can accelerate their growth and development, improve the quality of plants and fruits. Despite the impressive characteristics of LED irradiators, arc sodium tube lamps continue to be competitive when used as the main lighting in greenhouses.
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Zhang, Yuan Yuan, Xiao Fei Lu, Rong Cai, Jie Gong, Shan Liu, and Jian Yu Bao. "Design of an Intelligent Solar-LED Streetlight." Applied Mechanics and Materials 548-549 (April 2014): 873–79. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.873.
Abstract:
Solar-led streetlight is a hotspot in photovoltaic lighting at present, it combines solar energy with HB LEDs (High Brightness Light Emitting Diodes) called the fourth generation of light source to improve the conventional streetlight in several aspects. Due to the clean nature of solar energy, and the highly efficient energy conversion of the PV module and very long operating life of the HB LED, the solar-LED streetlight, compared to traditional streetlight, can save electricity remarkably, thus abating greenhouse gas emission. During the photovoltaic lighting system, MPPT technology is generally used with the aim of maximizing the solar panel output power from beginning to the end. Therefore, if the controller combines MPPT technology with the traditionally constant-voltage charging technology, the charge efficiency will be greatly increased. While, for the discharge issue, people hope to modulate the brightness of streetlight so as to decrease the electricity consume.
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Kamarudin, S. N., M. T. Ali, S. Subahir, A. A. Azlan, S. Muhamud-Kayat, and Muhammad Ramlee Kamarudin. "Design and Investigation of H-Shaped Patch Antenna Integrated with Light Emitting Diodes." Applied Mechanics and Materials 781 (August 2015): 106–9. http://dx.doi.org/10.4028/www.scientific.net/amm.781.106.
Abstract:
The limitations in the applications of microstrip antenna lead to wastage in the form of space and functionality. In order to overcome the wastage of space and functionality of the microstrip antenna, the new idea is to make one single device of microstrip antenna which has two application at the same time where it can operates as antenna and the function as lighting source is proposed. Light Emitting Diode (LED) has been chosen as the light source since the characteristic and the structure of the LED are suitable for the integration process. Hence, this paper presents an investigation on the characteristic of an H-shaped patch antenna integrated with Light Emitting Diodes (LEDs).The proposed integrated antenna has been designed and simulated by using Computer Simulation Technology (CST) Microwave Studio Software. It has been fabricated and measured to investigate the performance of the antenna in terms of return loss. The results confirms that the antenna can operate at 2.4 GHz and it works well as an illumination.
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Bourget, C. Michael. "An Introduction to Light-emitting Diodes." HortScience 43, no. 7 (December 2008): 1944–46. http://dx.doi.org/10.21273/hortsci.43.7.1944.
Abstract:
Light-emitting diodes (LEDs) are semiconductor devices that produce noncoherent, narrow-spectrum light when forward voltage is applied. LEDs range in wavelength from the UVC band to infrared (IR) and are available in packages ranging from milliwatts to more than 10 W. The first LED was an IR-emitting device and was patented in 1961. In 1962, the first practical visible spectrum LED was developed. The first high-power (1-W) LEDs were developed in the late 1990s. LEDs create light through a semiconductor process rather than with a superheated element, ionized gas, or an arc discharge as in traditional light sources. The wavelength of the light emitted is determined by the materials used to form the semiconductor junction. LEDs produce more light per electrical watt than incandescent lamps with the latest devices rivaling fluorescent tubes in energy efficiency. They are solid-state devices, which are much more robust than any glass-envelope lamp and contain no hazardous materials like fluorescent lamps. LEDs also have a much longer lifetime than incandescent, fluorescent, and high-density discharge lamps (U.S. Dept. of Energy). Although LEDs possess many advantages over traditional light sources, a total system approach must be considered when designing an LED-based lighting system. LEDs do not radiate heat directly, but do produce heat that must be removed to ensure maximum performance and lifetime. LEDs require a constant-current DC power source rather than a standard AC line voltage. Finally, because LEDs are directional light sources, external optics may be necessary to produce the desired light distribution. A properly designed LED light system is capable of providing performance and a lifetime well beyond any traditional lighting source.
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Sobczynski, Dariusz. "The influence of power electronic converter passive filter parameters for flicker in LED lighting." ITM Web of Conferences 21 (2018): 00020. http://dx.doi.org/10.1051/itmconf/20182100020.
Abstract:
The light emitting diodes (LEDs) are ever more used, and their price is getting lower year on year. Although, exchanging traditional light sources for the LED lamps does not seem to be complicated, we need to remember to maintaining high–quality of light. One of the aspects we should be worry about is a light’s flickering. Due to the shape of the current–voltage characteristics of the LED diode and their dependence on temperature, the value of the luminous flux – but also the lifetime – depends to a large extent on the stability of the supply voltage. Therefore, correct power system should be a thermally stable current source. Unfortunately, the simple power systems, equipped with passive filters are often used as cheap commercial solutions. In those types of systems stability of the output voltage is heavily dependent on the load conditions. Passive filters – usually consisting of coils and capacitors – are placed in the output circuit. This paper presents research carried out to show of filter capacitance influence on flickering phenomenon, and practical light’s flickering measuring technique for the LED lamps.
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Behar-Cohen, F., C. Martinsons, F. Viénot, G. Zissis, A. Barlier-Salsi, J. P. Cesarini, O. Enouf, M. Garcia, S. Picaud, and D. Attia. "Light-emitting diodes (LED) for domestic lighting: Any risks for the eye?" Progress in Retinal and Eye Research 30, no. 4 (July 2011): 239–57. http://dx.doi.org/10.1016/j.preteyeres.2011.04.002.
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Bartz, Brooke, and Jesse L. Grimes. "The use of mixed light-emitting diodes and natural light in combination with daylength affects turkey hen performance, eye development, and feather coverage." Turkey Diseases, Production and Management 1, no. 3 (October 3, 2021): 67–77. http://dx.doi.org/10.51585/gjvr.2021.3.0023.
Abstract:
Lighting is a complex management tool in turkey production, controlled by three parameters; daylength, intensity, and chromaticity. As light-emitting diodes (LED) increase in popularity as alternatives to traditional light sources, research regarding LED impacts on commercial-type turkey production is lacking. Therefore, turkey hens of the same strain were reared under experimental brooding and grow-out conditions with six lighting treatments. An environmentally and light controlled facility (ECF) consisted of 5,000 Kelvin (K) LED or 5,000K + far-red LED (639nm) (RED) with either 12h short or 18h long daylength to test LED spectra. In the remaining treatments, hens were exposed to sunlight in a curtain-sided facility (CSF) as two treatments 1) natural decreasing daylength from September to November (NAT) or 2) natural daylight + 5,000 K LED lighting with an 18h long blocked daylength (BLK). The intensity was 9 footcandles in the ECF and naturally fluctuating in the CSF. Hen's performance was evaluated at 5, 9, and 14 weeks for eye development and feather coverage. Hens brooded and grown-out under NAT light had significantly increased body weight gain compared to BLK hens for the same period. Hens reared with RED LED spectrum had significantly increased eye anterior-posterior distance than birds raised in the NAT treatment. A significant reduction in red heat signature on the breast tissue in the NAT treatment compared to all other 18h treatments indicated improved feather coverage. However, these same results were not observed during serum thyroid hormone analysis. While turkey hens reared under different lighting programs had similar ending performance, lighting parameters significantly affected bird performance during the growing period, bird's eye development, and body feather coverage. Therefore, potential effects on growth patterns and physiology should be considered when choosing a LED lighting program for turkeys
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Ciugudeanu, Calin, Mircea Buzdugan, Dorin Beu, Angel Campianu, and Catalin Daniel Galatanu. "Sustainable Lighting-Retrofit Versus Dedicated Luminaires-Light Versus Power Quality." Sustainability 11, no. 24 (December 12, 2019): 7125. http://dx.doi.org/10.3390/su11247125.
Abstract:
For the next few years millions of fluorescent luminaires will become waste and will be replaced by light-emitting diodes—LED luminaires. According to the Cost European Cooperation in Science & Technology Program, the next step will be shifting from sustainability to regeneration (enabling social and ecological systems to maintain a healthy state and to evolve); to reach this point, a is circular economy becomes necessary. The Technical University of Cluj-Napoca’s Lighting Engineering Laboratory—LEL—is the main lighting independent consultant in Transylvania (the north-west region of Romania). For the Building Services Faculty, LEL adopted different energy efficient lighting solutions to replace existing fluorescent T8 luminaires. The best available techniques were evaluated over the last few years. Out of a range of different smart lighting control systems, LED were chosen and used for retrofitting the existing T8 luminaires or simply replacing them with new dedicated LED luminaires. The study analyzed five different lighting setups for upgrading the existing fluorescent T8 2*36W luminaires. One setup used T5 lamps and the others used retrofitted or dedicated LED lighting solutions. First the lighting quantities of each setup were evaluated under real and experimental conditions. Second, a programable power source was used for measuring power quality indicators corelated with the provided lighting outputs, under different voltage values and waveforms. For each lighting setup, an even and odd current harmonic limit check was performed in line with class C—lighting equipment, IEC 61000-3-2 requirements. A new energy efficiency and power quality indicator was proposed—the lighting apparent power density [VA/sq.m/100lx].
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Lisovenko, V., D. Lisovenko, and O. Bazyk. "LED MODULE WITH ELECTRONIC ILLUMINATION CONTROL." Collection of scientific works of Odesa Military Academy 1, no. 12 (December 27, 2019): 146–54. http://dx.doi.org/10.37129/2313-7509.2019.12.1.146-154.
Abstract:
Many energy saving tasks can be solved thanks to the current advances in LED technology in the production of semiconductor light sources. Modern production of solid-state LEDs guarantees high-precision compliance with the calculated design parameters of illumination devices. This opens up wide opportunities for high-precision control of the lighting parameters of a multicomponent module: light power, a directional pattern and a distribution of illumination. Today, the methodical issues of the preliminary modeling of LED illumination devices with the given parameters are fundamentally solved. There is a shift from manual calculations to computer design and need to develop and select the most effective mathematical modeling methods. The paper presents a consistent approach to the modeling of the distribution of illumination on a horizontal plane from the planar LED module, based on the Lambert type of radiation of a single point source. Simple mathematical expressions, programmed on a personal computer, are obtained. The example of a 25-LED floodlight has shown the ability of dynamic control the lighting characteristics of the module. Connecting patterns of separate LEDs or their groups allow to change the direction pattern of the lamp by the appropriate way of switching diodes with different aperture of radiation. The lighting power can be controlled within the linearity of the ampere-brightness characteristics by changing the current strength through the LED. The static selection of characteristics is controlled by the geometry of the location of discrete sources. The formation of uniform illumination of the plane is graphically illustrated. The electron-dynamic way of controlling the lighting parameters of the LED floodlight is confirmed by the inventor’s certificate.
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Jägerbrand, Annika. "New Framework of Sustainable Indicators for Outdoor LED (Light Emitting Diodes) Lighting and SSL (Solid State Lighting)." Sustainability 7, no. 1 (January 19, 2015): 1028–63. http://dx.doi.org/10.3390/su7011028.
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Sobczak, Anna, Marzena Sujkowska-Rybkowska, Janina Gajc-Wolska, Waldemar Kowalczyk, Wojciech Borucki, Hazem M. Kalaji, and Katarzyna Kowalczyk. "Photosynthetic Efficiency and Anatomical Structure of Pepper Leaf (Capsicum annuum L.) Transplants Grown under High-Pressure Sodium (HPS) and Light-Emitting Diode (LED) Supplementary Lighting Systems." Plants 10, no. 10 (September 22, 2021): 1975. http://dx.doi.org/10.3390/plants10101975.
Abstract:
The aim of this study was to evaluate the effects of various supplemental greenhouse lighting systems, i.e., high-pressure sodium lamps and mixtures of red and blue light-emitting diodes, on the photochemical efficiency, anatomical leaf structure, and growth of the two pepper cultivars. The intensity levels of the photosynthetically active radiation were the same for both light treatments. In this study, the relative chlorophyll content was measured. Additionally, certain parameters of chlorophyll a fluorescence were measured under ambient light or after dark adaptation. The obtained results showed that the application of light-emitting diodes (LEDs) as supplemental lighting positively affected the anatomical leaf characteristics and plant growth. The leaves of both pepper cultivars were thicker and had larger palisade parenchyma cells under LED supplemental lighting compared to leaves grown under high-pressure sodium (HPS) lamps. Moreover, the mesophyll cells of seedlings grown under LEDs contained more chloroplasts than those growing under HPS lighting. The chlorophyll a fluorescence measurements of pepper seedlings grown under LEDs showed significant increases in photosynthetic apparatus performance index (PI) values compared to plants grown under HPS lamps; however, the values for this index were higher in cv. ‘Aifos’ as compared to cv. ‘Palermo’. We recommend that supplemental lighting systems are applied with caution, as their performance appears to depend not only on the light spectrum but also on the cultivar.
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Paucek, Ivan, Elisa Appolloni, Giuseppina Pennisi, Stefania Quaini, Giorgio Gianquinto, and Francesco Orsini. "LED Lighting Systems for Horticulture: Business Growth and Global Distribution." Sustainability 12, no. 18 (September 11, 2020): 7516. http://dx.doi.org/10.3390/su12187516.
Abstract:
In recent years, research on light emitting diodes (LEDs) has highlighted their great potential as a lighting system for plant growth, development and metabolism control. The suitability of LED devices for plant cultivation has turned the technology into a main component in controlled or closed plant-growing environments, experiencing an extremely fast development of horticulture LED metrics. In this context, the present study aims to provide an insight into the current global horticulture LED industry and the present features and potentialities for LEDs’ applications. An updated review of this industry has been integrated through a database compilation of 301 manufacturers and 1473 LED lighting systems for plant growth. The research identifies Europe (40%) and North America (29%) as the main regions for production. Additionally, the current LED luminaires’ lifespans show 10 and 30% losses of light output after 45,000 and 60,000 working hours on average, respectively, while the vast majority of worldwide LED lighting systems present efficacy values ranging from 2 to 3 μmol J−1 (70%). Thus, an update on the status of the horticultural LED sector, LEDs’ applications and metrics, and the intense innovation are described and discussed.
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Taguchi, Tsunemasa. "The 21st Century Lighting Based on White Light-Emitting Diodes (LEDs)." JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN 85, no. 7 (2001): 496–501. http://dx.doi.org/10.2150/jieij1980.85.7_496.
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Bartseva, Aleksandra A., George V. Boos, Anatoly Sh Chernyak, Alyona B. Kuznetsova, and Eugene I. Rozovsky. "The State of Museum Lighting in Russia." Volume 28, Number 2, 2020, no. 02-2020 (April 2020): 38–46. http://dx.doi.org/10.33383/2019-054.
Abstract:
The article contains the results of analysis of answers of 90 museums of the Russian Federation to questions regarding lighting of these museums as well as the results of inspection and measurement of lighting parameters (average exhibit illuminance, correlated colour temperature, colour rendering index, and luminance distribution) conducted in 7 museums and 1 conservation centre. It is found that museum lighting in the Russian Federation generally complies with the applicable requirements and recommendations and requires fundamental changes only in few cases. Many museums already use light emitting diodes (LEDs) as light sources and are ready to cross over to LED lighting completely. In the meantime, museums (primarily small ones) consider lack of regulations in the sphere of museum lighting one of the major problems.
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Apostolidou, Nena, Fotis Valsamas, Dimitris Baros, Michael Loupis, Vasilios Dasteridis, and Charalampos Kokkinis. "Innovative Energy-Recovery Unit for the LED-Lighting System of Heavy-Duty Vehicles." Clean Technologies 3, no. 3 (August 4, 2021): 581–93. http://dx.doi.org/10.3390/cleantechnol3030035.
Abstract:
In this work, the development of an energy recovery control unit to be incorporated in the light-emitting diodes (LEDs) lighting systems of heavy-duty vehicles is presented. This innovative industrial product adopts modern power electronics technology to improve existing trucks’ LED lighting system by eliminating the so far inevitable power consumption by the conventional central control unit of the majority of these vehicles, which is obligatory for the uninterruptable operation of their lighting system. The main idea of this innovative product is its capability to virtually increase the lighting system power consumption without actually consuming this amount of energy, thus facilitating the central control unit requirements regarding these vehicles in an energy-conscious way. Under this light, a mature power converter’s topology is employed to draw the proper amounts of power from the vehicle’s batteries supply, to the level that the central control unit recognizes, and return this energy back to the batteries. The tests results of the developed industrial product highlight the energy saving potential of the proposed energy recovery scheme, while the Life Cycle Cost Analysis (LCCA) results confirm its techno-economical and environmental profit for the truck applications under study.
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Aldarkazali, Rihan, Carne, and Fuller. "The Growth and Development of Sweet Basil (Ocimum basilicum) and Bush Basil (Ocimum minimum) Grown under Three Light Regimes in a Controlled Environment." Agronomy 9, no. 11 (November 11, 2019): 743. http://dx.doi.org/10.3390/agronomy9110743.
Abstract:
Light is a crucial element for plant growth and production. In areas where natural light is not sufficient for optimal plant growth and production, high pressure sodium (HPS) light sources are widely used. However, HPS lamps are considered not very electrically efficient generating high radiant heat and as a consequence, there has been a lot of interest in replacing HPS lamps with new more efficient lighting sources in the form of light-emitting diodes (LEDs). The effects of three lighting sources (White LED, Blue/Red LED and HPS) on the growth, development and on the essential oil yield and quality of sweet basil and bush basil were investigated. There was a clear advantage to the Blue/Red (452 nm and 632 nm, respectively) LED on virtually all growth and physiological parameters measured for both basil species. The HPS lighting system always performed least effectively in all comparisons. Combining increases in plant yield and increases in oil yield the Blue/Red LED array outperformed the HPS lights by a factor of approximately double, with the white LED being intermediate between these two extremes.
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Reinhardt, Annemarie, Aleksander Zych, Ingo Köhler, and Barbara Albert. "Disordered langasites La3Ga5MO14 : Eu3+ (M = Si, Ge, Ti) as red-emitting LED phosphors." Dalton Transactions 47, no. 16 (2018): 5703–13. http://dx.doi.org/10.1039/c8dt00671g.
Abstract:
Polycrystalline powders of La3Ga5SiO14 (LGSi), La3Ga5GeO14 (LGGe), and La3Ga5TiO14 (LGTi) doped with Eu3+ were studied with respect to their use as luminescent materials in solid state lighting based on light-emitting diodes.
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Nguyen, Si Tien, and An Dinh Pham. "Estimate the Meaning-Time-To-Failure of LED driver using Numerical simulation." Journal of Mining and Earth Sciences 62, no. 6 (December 31, 2021): 64–71. http://dx.doi.org/10.46326/jmes.2021.62(6).09.
Abstract:
The Meaning-Time-To-Failure (MTTP), also known as Electromigration Analysis is an estimation of product life. Light-Emitting Diodes (LEDs) are usually driven by constant current switched-mode power supplies, which are invented early than LEDs for lighting applications. While LEDs themselves are extremely reliable and have a long lifetime, the electronic LED drivers in experiment usually fail due to overheating causing Printed Circuit Boards (PCBs) explosion, inability provide current/voltage input to the LEDs over their whole lifetime. This paper proposes a numerical simulation method to predict fault location on PCB of LED driver based on 2-way coupling electro-thermal multiphysic analysis, then applies the analytic models to calculate the time to failure of the points on PCB of LED drivers. The procedures can be applied to assist managers in assessing risk and making LED-based lighting system reliability decisions.
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Jeong, Junseok, Qingxiao Wang, Janghwan Cha, Dae Kwon Jin, Dong Hoon Shin, Sunah Kwon, Bong Kyun Kang, et al. "Remote heteroepitaxy of GaN microrod heterostructures for deformable light-emitting diodes and wafer recycle." Science Advances 6, no. 23 (June 2020): eaaz5180. http://dx.doi.org/10.1126/sciadv.aaz5180.
Abstract:
There have been rapidly increasing demands for flexible lighting apparatus, and micrometer-scale light-emitting diodes (LEDs) are regarded as one of the promising lighting sources for deformable device applications. Herein, we demonstrate a method of creating a deformable LED, based on remote heteroepitaxy of GaN microrod (MR) p-n junction arrays on c-Al2O3 wafer across graphene. The use of graphene allows the transfer of MR LED arrays onto a copper plate, and spatially separate MR arrays offer ideal device geometry suitable for deformable LED in various shapes without serious device performance degradation. Moreover, remote heteroepitaxy also allows the wafer to be reused, allowing reproducible production of MR LEDs using a single substrate without noticeable device degradation. The remote heteroepitaxial relation is determined by high-resolution scanning transmission electron microscopy, and the density functional theory simulations clarify how the remote heteroepitaxy is made possible through graphene.
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Agrawal, Deepak, Rajneesh Kumar Karn, Deepak Verma, and Rakeshwri Agrawal. "Modelling and Simulation of Integrated Topology of DC/DC converter for LED Driver Circuit." WSEAS TRANSACTIONS ON ELECTRONICS 11 (May 7, 2020): 18–21. http://dx.doi.org/10.37394/232017.2020.11.3.
Abstract:
With the increase in technological advancements and impetus to work for the reduction of electrical energy consumption among different types of consumers, there is a primary need to take into account all forms of energy efficiency improvement methods available for electric and electronic equipment been used. It has been noticed that in commercial lighting, in terms of efficiency light-lamps based on light-emitting diodes(LEDs) are far better as compared to those where traditional high pressure sodium (HPS) lamps which are still in use in major underdeveloped and developing areas worldwide in specifically street lighting. The LED have numerous advantages such as high luminous efficiency, life span and it has no mercury in its composition. Therefore, recently researchers of this area has been setting a goal to utilize LED as a good alternative to save electricity from major parts of this planet. In this paper simulation of LED driver circuit is presented to utilize the 12 V LED lighting strip which has been used in Indian hawkers/small shopkeepers since a long time.
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Jeong, Jin Wook, Young Wook Park, Tae Hyun Park, Jin Hwan Choi, Hyun Ju Choi, Eun Ho Song, Jeong Ik Lee, Hye Yong Chu, and Byeong Kwon Ju. "The Emission Properties of Integrated Organic Light Emitting Diodes With Organic Photo Sensor for Emotional Lighting Applications." IEEE Electron Device Letters 32, no. 3 (March 2011): 348–50. http://dx.doi.org/10.1109/led.2010.2099099.
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Erdem, Talha, Yusuf Kelestemur, Zeliha Soran-Erdem, Yun Ji, and Hilmi Volkan Demir. "Energy-saving quality road lighting with colloidal quantum dot nanophosphors." Nanophotonics 3, no. 6 (December 1, 2014): 373–81. http://dx.doi.org/10.1515/nanoph-2014-0016.
Abstract:
AbstractHere the first photometric study of road-lighting white light-emitting diodes (WLEDs) integrated with semiconductor colloidal quantum dots (QDs) is reported enabling higher luminance than conventional light sources, specifically in mesopic vision regimes essential to street lighting. Investigating over 100 million designs uncovers that quality road-lighting QD-WLEDs, with a color quality scale and color rendering index ≥85, enables 13–35% higher mesopic luminance than the sources commonly used in street lighting. Furthermore, these QD-WLEDs were shown to be electrically more efficient than conventional sources with power conversion efficiencies ≥16–29%. Considering this fact, an experimental proof-of-concept QD-WLED was demonstrated, which is the first account of QD based color conversion custom designed for street lighting applications. The obtained white LED achieved the targeted mesopic luminance levels in accordance with the road lighting standards of the USA and the UK. These results indicate that road-lighting QD-WLEDs are strongly promising for energy-saving quality road lighting.
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Hao, R., A. Ge, X. Tao, Y. Liu, B. Zhao, and E. Yang. "Optical design of a high-mast luminaire based on four COB LED light source modules." Lighting Research & Technology 51, no. 3 (May 14, 2018): 447–56. http://dx.doi.org/10.1177/1477153518764774.
Abstract:
Light-emitting diodes (LEDs) have been widely used in road lighting. This study investigates the optical design of a high-mast luminaire based on four chips-on-board LED light source modules and applies it to road lighting. The model of the high-mast luminaire is built with Solidworks, and then the optical simulations are analysed by Tracepro and Dialux. We also make a physical prototype of the high-mast luminaire to test its performance in practice. The illuminance distribution of the test area is nearly rectangular. The interior of the rectangle forms a smaller highlighted rectangular illumination area with uniform illumination. The outer edges of the rectangular illumination area will overlap the outer edges of the illumination area of other high-mast luminaires. The desired illuminance distribution and the uniform illumination can be obtained. Both the simulations and the experimental results meet the requirements of road lighting standards and the high-mast lamp can even achieve a better optical performance.
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Kowalczyk, Katarzyna, Dawid Olewnicki, Małgorzata Mirgos, and Janina Gajc-Wolska. "Comparison of Selected Costs in Greenhouse Cucumber Production with LED and HPS Supplemental Assimilation Lighting." Agronomy 10, no. 9 (September 7, 2020): 1342. http://dx.doi.org/10.3390/agronomy10091342.
Abstract:
The amount of energy used in agricultural production, processing and distribution is constantly increasing. During the winter months in the greenhouse production industry, the supplemental lighting required to keep up production levels results in high expenditure. Current technology uses broadband high-pressure sodium (HPS) lamps, which is not the most efficient light source for crop production. Recent breakthroughs in the development of light source technologies have led to new opportunities for the use of sustainable and highly efficient light sources in the form of LEDs (light-emitting diodes) for greenhouse lighting. The aim of the study was to evaluate the efficiency of using photosynthetically active radiation (PAR) light for cucumber yielding, production processes and its influence on the variable costs in the cultivation of cucumbers using three different types of lighting. The research was carried out using three individual greenhouse growing area compartments, whereby the plants contained within were lit using three combinations: 1. HPS standard illumination from top HPS sodium lamps—control, 2. HPS-LED—HPS toplighting and LED interlighting, and 3. LED-LED—100% LED lighting, both toplighting and interlighting with LED. The research was conducted in two independent winter crop cycles. The results of the research conducted indicate that the efficiency of light use was the highest in the LED-LED combination and the lowest in HPS, and the use of supplemental lamp lighting in the LED-LED combination (interlighting and toplighting) gives the most favorable surplus of all the variable costs over the value of production to be obtained. Despite the highest absolute level of variable costs in this type of supplemental lighting, the production value was higher by as much as 32.55% in relation to the HPS combination, which also translated into a gross margin that was higher by about ¾. However, it is worth pointing out that, in the HPS-LED combination, the share of lighting and heating costs in the total value of production was the lowest. It is also a combination currently recommended in the literature as being the most beneficial in greenhouse production.
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Li, Lizhu, Guo Tang, Zhao Shi, He Ding, Changbo Liu, Dali Cheng, Qianyi Zhang, et al. "Transfer-printed, tandem microscale light-emitting diodes for full-color displays." Proceedings of the National Academy of Sciences 118, no. 18 (April 26, 2021): e2023436118. http://dx.doi.org/10.1073/pnas.2023436118.
Abstract:
Inorganic semiconductor-based microscale light-emitting diodes (micro-LEDs) have been widely considered the key solution to next-generation, ubiquitous lighting and display systems, with their efficiency, brightness, contrast, stability, and dynamic response superior to liquid crystal or organic-based counterparts. However, the reduction of micro-LED sizes leads to the deteriorated device performance and increased difficulties in manufacturing. Here, we report a tandem device scheme based on stacked red, green, and blue (RGB) micro-LEDs, for the realization of full-color lighting and displays. Thin-film micro-LEDs (size ∼100 μm, thickness ∼5 μm) based on III–V compound semiconductors are vertically assembled via epitaxial liftoff and transfer printing. A thin-film dielectric-based optical filter serves as a wavelength-selective interface for performance enhancement. Furthermore, we prototype arrays of tandem RGB micro-LEDs and demonstrate display capabilities. These materials and device strategies provide a viable path to advanced lighting and display systems.
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Yang, Wonyoung, and Jin Yong Jeon. "Effects of Correlated Colour Temperature of LED Light on Visual Sensation, Perception, and Cognitive Performance in a Classroom Lighting Environment." Sustainability 12, no. 10 (May 15, 2020): 4051. http://dx.doi.org/10.3390/su12104051.
Abstract:
Illuminance levels have been standardized and regulated for many purposes. However, the effects of correlated colour temperature of lighting have received little attention in the field. This study investigated the effects of correlated colour temperature of lighting on the brightness sensation, lighting perception, and cognitive performance of 60 students under ambient light emitting diodes (LED) lighting conditions (CCT: 3000 K, 4000 K, and 5700 K; illuminance: 650 lx and 1050 lx) in an actual university classroom. An increase in correlated colour temperature (CCT) led to an increase in brightness sensation. However, increased CCT did not linearly increase lighting comfort. A CCT of 4000 K was considered as the optimum for lighting comfort in educational settings. But in comparison to comfort, higher levels of perceptual properties, satisfaction and acceptance were not affected by CCT from 3000 K to 5700 K. Scores on the working memory test were significantly affected by CCT and illuminance level in men only. The effects of gender appeared in glare sensation and the working memory test. Women were sensitive to glare sensation and had a lower mean score in the working memory test than men. Optimal CCT is more beneficial than increased illuminance in moderately ambient indoor lighting, as it provides better lighting comfort. Further research can look at the long-term effects of CCT on lighting perception depending on brain processing levels and more diverse and in-depth cognitive performance.