Testing of Various Monochromatic LED Lights Used in Supplemental Irradiation of Lettuce in Modern Urban Rooftop Polytunnels

2019 ◽  
Vol 35 (3) ◽  
pp. 439-452
Author(s):  
Chung-Liang Chang ◽  
Kuang-Pi Chang ◽  
Wei-Lun Fu
Keyword(s):  
Light Emitting Diodes ◽  
Environmental Parameters ◽  
Quality Parameters ◽  
Urban Heat Islands ◽  
Direct Access ◽  
Urban Farming ◽  
Light Emitting ◽  
Fresh Vegetables ◽  
Lighting Systems ◽  
Led Lights

Abstract. Urban farming could provide both vegetable growers and urban dwellers with more direct access to various fresh vegetables. Nevertheless, certain challenging problems associated with urban farming, including a lack of cultivation space and the effects of urban heat islands, must still be solved. Relatedly, a grower must, in some cases, also know how to utilize various forms of technology, such as lighting systems, as well as factors such as water availability. In this study, an original rooftop polytunnel design for lettuce ( cv. Lollo Rosso) cultivation equipped with a hydroponic system and light emitting diodes (LEDs) is proposed. Various monochromatic lights were also tested for their effects on different quality parameters of lettuce. Specifically, supplemental red (655 nm), blue (445 nm), green (520 nm), and ultraviolet (380 nm) LED lights were used at night to apply photon fluxes of 150, 150, 150, and 20 µmol.m-2.s-1, respectively. The resulting effects of these different colored LEDs on the pigment concentration and growth response of the lettuce grown inside the roof polytunnel were then investigated. The experiment was then repeated several times with different environmental parameters in order to compare the effects of the different light wavelengths under higher temperatures and higher natural irradiation conditions.The results indicated that supplemental red or blue light at night could be strategically employed to maintain low nitrate levels and enhance the nutritional value and growth of lettuce grown in roof polytunnels. Keywords: Light emitting-diodes, LEDs, Hydroponic, Red lettuce, Rooftop polytunnel, Urban agriculture.

scholarly journals Effect of Light-Emitting Diodes (LEDs) on Some Physical and Bioactive Compounds of ‘Iceberg’ Lettuce (Lactuca Sativa L.)

2021 ◽  
Vol 4 (1) ◽  
pp. 21-30
Author(s):  
Asmaa Sayed Ahmed ◽  
Arshad Abdulkhalq Yaseen ◽  
Triska Dlshad Bakr
Keyword(s):  
Chlorophyll Content ◽  
Lactuca Sativa ◽  
Light Emitting Diodes ◽  
Quality Parameters ◽  
The Other ◽  
Carotenoid Content ◽  
Nitrate Content ◽  
Light Emitting ◽  
Iceberg Lettuce ◽  
Led Lights

Abstract The use of light-emitting diodes (LEDs) is a recent concerned application in the indoor crop system of the modern plant production. In our research, we evaluated the influence of four monochromic LED lights including 100% White (W), Yellow (Y), Red (R) and Blue (B) in comparison to solar lightening condition (GR) as a control. In this regard, some morphological characteristics and biochemical content of the common outdoor ‘Iceberg’ lettuce (Lactuca sativa L.) was measured. The results show that leaf length, leaf area and total head weight were significantly greater in the plants grown under B LED, while all the other physical parameters were significantly higher in the plants grown under GR environmental conditions. On the other hand, chlorophyll (Chl), carotenoids (Car), and nitrate content were also influenced by different light treatments. Plants grown under LED light treatment resulted in significantly higher chlorophyll content compared to the control. However, significantly greater carotenoid content was in the plants grown under GR condition. The highest total chlorophyll content was recorded under B and R LED, whereas the lowest was in the GR condition. The lowest nitrate content in the blade and petiole was recorded in the plants grown under Y LED, while the highest nitrate content was recorded in the GR. Based on our result, it is possible to grow and improve some quality parameters of common outdoor ‘iceberg’ lettuce under LED where the solar light is limited or unavailable. Thus, plants performed better under GR light conditions than monochromic LEDs; however, some LED lights could improve some quality parameters and biochemical contents in the ‘iceberg’ lettuce variety.

scholarly journals Light-Emitting Diodes (LED): A Promising Street Light System to Reduce the Attraction to Light of Insects

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 89
Author(s):  
Beatriz Martín ◽  
Héctor Pérez ◽  
Miguel Ferrer
Keyword(s):  
Light Emitting Diodes ◽  
Ecological Impacts ◽  
Light Emitting ◽  
Light System ◽  
Wide Range ◽  
Lower Light ◽  
Lighting Systems ◽  
Negative Impacts ◽  
Short Wavelength Light ◽  
Led Lights

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.

Assessing the impact of the transition to Light Emitting Diodes based solar lighting systems in India

2013 ◽  
Vol 17 (4) ◽  
pp. 363-370 ◽  
Author(s):  
Santosh M. Harish ◽  
Shuba V. Raghavan ◽  
Milind Kandlikar ◽  
Gireesh Shrimali
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
Solar Lighting ◽  
Lighting Systems ◽  
The Impact

Cost-Effective Light-Mixing Module for Solar-Lighting System Appended With Auxiliary RGBW Light-Emitting Diodes

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
An Chi Wei ◽  
Shih Chieh Lo ◽  
Ju-Yi Lee ◽  
Hong-Yih Yeh
Keyword(s):  
Light Source ◽  
Light Emitting Diodes ◽  
Cylindrical Tube ◽  
Cost Effective ◽  
Lighting System ◽  
Optical Efficiency ◽  
Light Emitting ◽  
Solar Lighting ◽  
Lighting Systems ◽  
Main Components

A light-mixing module consisting of a compound parabolic concentrator (CPC) and a light-mixing tube is proposed herein to realize a uniform and efficient solar-lighting system. In this lighting system, the sunlight collected into a fiber and then guided to an indoor destination is the principal light source, while an auxiliary light source including multiple red, green, blue, and white (RGBW) light-emitting diodes (LEDs) is controlled by an auto-compensating module. To mix the principal and the auxiliary sources and to realize the uniform illumination, the light-mixing tube was coated with BaSO4 and optimized as a cylindrical tube. The design of the light-mixing tube is described and discussed in this article. According to the simulated results, the uniformity and the optical efficiency of the designed light-mixing tube are 82.9% and 85.7%, respectively, while from the experimental results, the uniformity of 85.9% and the optical efficiency of 83.3% have been obtained. In terms of the common indoor-lighting standards and the specifications of commercial components used in lighting systems, the proposed light-mixing module has demonstrated the high uniformity and acceptable optical efficiency. Additionally, since the main components of the light-mixing module can be designed as plastic optics, a cost-effective light-mixing module and a profitable lighting system can be realized. Thus, the performance and the price of the proposed light-mixing module fit the demands of the illumination market, while the proposed system shows the potential for indoor solar-lighting applications.

scholarly journals Assessment of the optical and electrical properties of light-emitting diodes containing carbon-based nanostructures and plasmonic nanoparticles: a review

2021 ◽  
Vol 12 ◽  
pp. 1078-1092
Author(s):  
Keshav Nagpal ◽  
Erwan Rauwel ◽  
Frédérique Ducroquet ◽  
Protima Rauwel
Keyword(s):  
Thermal Management ◽  
Carbon Nanostructures ◽  
Light Emitting Diodes ◽  
Plasmonic Nanoparticles ◽  
Device Performance ◽  
Optical And Electrical Properties ◽  
Light Emitting ◽  
Flexible Devices ◽  
Turn On ◽  
Lighting Systems

Light-emitting diodes (LED) are widely employed in display applications and lighting systems. Further research on LED that incorporates carbon nanostructures and metal nanoparticles exhibiting surface plasmon resonance has demonstrated a significant improvement in device performance. These devices offer lower turn-on voltages, higher external quantum efficiencies, and luminance. De facto, plasmonic nanoparticles, such as Au and Ag have boosted the luminance of red, green, and blue emissions. When combined with carbon nanostructures they additionally offer new possibilities towards lightweight and flexible devices with better thermal management. This review surveys the diverse possibilities to combine various inorganic, organic, and carbon nanostructures along with plasmonic nanoparticles. Such combinations would allow an enhancement in the overall properties of LED.

Performance of chip-on-board and surface-mounted high-power LED luminaires at different relative humidities and temperatures

2018 ◽  
Vol 51 (8) ◽  
pp. 1249-1262
Author(s):  
D Raul ◽  
K Ghosh
Keyword(s):  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Light Sources ◽  
Ambient Conditions ◽  
Light Emitting ◽  
Tropical Conditions ◽  
Temperature Ageing ◽  
Lighting Systems ◽  
State Device ◽  
Solid State Device

In today's world, light-emitting diodes are quickly replacing conventional light sources, both indoors and outdoors. Being a solid-state device, adverse ambient conditions such as high temperature and humidity lead to its poor performances, light quality and longevity. In outdoor applications, exposure to high ambient temperature during daytime, even when the lamp power is off, causes the lamp performance to deteriorate. In tropical countries, the environmental temperature in most of the days is higher than 25℃ and sometimes reaches 50℃. Here, the humidity varies between 30% and 80% and frequently over 80%. Thus, the reliability of the light emitting diodes is a question that needs a thorough study. In line with this, in this study, an effort has been made through an experiment. Here, commercially available surface-mounted device and chip-on-board-based light-emitting diodes are tested through an environmental chamber, and their measured illuminance values were observed by varying the relative humidity. Then, the temperature ageing or stress was set at 60℃ on the above types of light-emitting diodes at power off condition for 6000 hours and after that its luminous flux and spectral distribution were observed. The degradation observed under these conditions may guide designers and manufacturers to upgrade their lighting systems to make them fit for tropical conditions.

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