Adoption and consequences of new light-fishing technology (LEDs) on Lake Tanganyika, East Africa

AbstractMaintaining sustainable fisheries requires understanding the influence of technological advances on catch efficiency. Fisheries using light sources for attraction could be widely impacted by the shift to light emitting diode (LED) light systems. We studied the transition from kerosene lanterns to LED lamps in Lake Tanganyika, East Africa, examining factors that led to adoption as well as the impact of the new light sources on fish catch and composition. We used a combination of field experiments with catch assessments, fisher surveys, underwater light spectra measurements, and cost assessments to evaluate the impact of switching from kerosene to LED lamps. Overall, we found a very rapid rate of adoption of homemade outdoor LED light systems in Lake Tanganyika. Most of the batteries used to power these lamps were charged from the city power grid, rather than photovoltaic cells. The LED light spectra was distinct from the kerosene light and penetrated much deeper into the water column. Regardless of light type, most of the fish caught within the two dominant species were below maturity, indicating that current fishery is not sustainable. Although the LED lamps were associated with a slight increase in catch, environmental factors, particularly distance offshore, were generally more important in determining fish catch size and composition. The main advantages of the LED lamps were the lower operating costs and their robustness in bad weather. Overall, the use of battery-powered LED lighting systems to attract fish in Lake Tanganyika appears to reduce economic costs but not contribute new impacts on the fishery.

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Analysis on High-Power Seaport LED Luminaire with Uniform Light Distribution Based on Optimized Lens and Heatsink

Applied Sciences ◽

10.3390/app11094035 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4035

Author(s):

Jinsheon Kim ◽

Jeungmo Kang ◽

Woojin Jang

Keyword(s):

Light Source ◽

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Light Distribution ◽

Light Sources ◽

Led Light ◽

High Power Led ◽

Distribution Requirement ◽

Lighting Application

In the case of light-emitting diode (LED) seaport luminaires, they should be designed in consideration of glare, average illuminance, and overall uniformity. Although it is possible to implement light distribution through auxiliary devices such as reflectors, it means increasing the weight and size of the luminaire, which reduces the feasibility. Considering the special environment of seaport luminaires, which are installed at a height of 30 m or more, it is necessary to reduce the weight of the device, facilitate replacement, and secure a light source with a long life. In this paper, an optimized lens design was investigated to provide uniform light distribution to meet the requirement in the seaport lighting application. Four types of lens were designed and fabricated to verify the uniform light distribution requirement for the seaport lighting application. Using numerical analysis, we optimized the lens that provides the required minimum overall uniformity for the seaport lighting application. A theoretical analysis for the heatsink structure and shape were conducted to reduce the heat from the high-power LED light sources up to 250 W. As a result of these analyses on the heat dissipation characteristics of the high-power LED light source used in the LED seaport luminaire, the heatsink with hexagonal-shape fins shows the best heat dissipation effect. Finally, a prototype LED seaport luminaire with an optimized lens and heat sink was fabricated and tested in a real seaport environment. The light distribution characteristics of this prototype LED seaport luminaire were compared with a commercial high-pressure sodium luminaire and metal halide luminaire.

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The Impact of Inhomogeneities in the Phosphor Distribution on the Device Performance of Phosphor-Converted High-Power White LED Light Sources

Journal of Lightwave Technology ◽

10.1109/jlt.2010.2079316 ◽

2010 ◽

Cited By ~ 31

Author(s):

C Sommer ◽

F Reil ◽

J R Krenn ◽

P Hartmann ◽

P Pachler ◽

...

Keyword(s):

High Power ◽

Device Performance ◽

Light Sources ◽

White Led ◽

Led Light ◽

The Impact

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Impact of Slope of Growing Trays on Productivity of Wheat Green Fodder by a Nutrient Film Technique System

Water ◽

10.3390/w12113009 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3009

Author(s):

Andrius Grigas ◽

Aurelija Kemzūraitė ◽

Dainius Steponavičius ◽

Aušra Steponavičienė ◽

Rolandas Domeika

Keyword(s):

Light Emitting Diode ◽

Tap Water ◽

Slope Angle ◽

Experimental Studies ◽

Matter Content ◽

Light Sources ◽

Dry Matter Content ◽

Nutrient Film Technique ◽

Indoor Lighting ◽

The Impact

Application of hydroponic systems in feed production has not been extensively studied. Therefore, there is insufficient data on the effect of the slope of hydroponic growing trays used in the nutrient film technique on wheat fodder yield and its qualitative parameters. The slope of the trays has only been studied for food crops. This study conducted experimental research using a nutrient film technique hydroponic fodder growing device to evaluate the impact of growing tray slope angle on hydroponic wheat fodder production. The slope angle of the growing trays was changed from 2.0% (1.15°) to 8.0% (4.57°) with increments of 1.5% (0.86°). This research used two different light sources for wheat sprout illumination: indoor lighting (fluorescent lamps) and light-emitting diode illumination. In addition, two nutrient solutions were used for sprout irrigation: tap water and a solution enriched with macro- and microelements. Experimental studies confirmed the hypothesis that the slope angle of growing trays significantly affects the yield of wheat fodder grown for seven days. Analyzing the results, we found that the highest yield of wheat fodder after seven days of cultivation was achieved with growing trays sloped by 6.5% and using indoor lighting. In addition, we achieved the highest wheat fodder dry matter content using a 6.5% slope angle. Experimental studies also confirmed the hypothesis that using macro- and micronutrients in the nutrient solution does not significantly affect the yield of wheat fodder grown hydroponically for seven days.

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Circadian Potency Spectrum with Extended Exposure to Polychromatic White LED Light under Workplace Conditions

Journal of Biological Rhythms ◽

10.1177/0748730420923164 ◽

2020 ◽

Vol 35 (4) ◽

pp. 405-415 ◽

Cited By ~ 1

Author(s):

Martin Moore-Ede ◽

Anneke Heitmann ◽

Rainer Guttkuhn

Keyword(s):

Spectral Sensitivity ◽

White Light ◽

Light Exposure ◽

Human Subjects ◽

Light Sources ◽

Led Light ◽

Light Spectra ◽

Timing System ◽

Circadian Timing System ◽

Spectral Sensitivity Curve

Electric light has enabled humans to conquer the night, but light exposure at night can disrupt the circadian timing system and is associated with a diverse range of health disorders. To provide adequate lighting for visual tasks without disrupting the human circadian timing system, a precise definition of circadian spectral sensitivity is required. Prior attempts to define the circadian spectral sensitivity curve have used short (≤90-min) monochromatic light exposures in dark-adapted human subjects or in vitro dark-adapted isolated retina or melanopsin. Several lines of evidence suggest that these dark-adapted circadian spectral sensitivity curves, in addition to 430- to 499-nm (blue) wavelength sensitivity, may include transient 400- to 429-nm (violet) and 500- to 560-nm (green) components mediated by cone- and rod-originated extrinsic inputs to intrinsically photosensitive retinal ganglion cells (ipRGCs), which decay over the first 2 h of extended light exposure. To test the hypothesis that the human circadian spectral sensitivity in light-adapted conditions may have a narrower, predominantly blue, sensitivity, we used 12-h continuous exposures of light-adapted healthy human subjects to 6 polychromatic white light-emitting diode (LED) light sources with diverse spectral power distributions at recommended workplace levels of illumination (540 lux) to determine their effect on the area under curve of the overnight (2000–0800 h) salivary melatonin. We derived a narrow steady-state human Circadian Potency spectral sensitivity curve with a peak at 477 nm and a full-width half-maximum of 438 to 493 nm. This light-adapted Circadian Potency spectral sensitivity permits the development of spectrally engineered LED light sources to minimize circadian disruption and address the health risks of light exposure at night in our 24/7 society, by alternating between daytime circadian stimulatory white light spectra and nocturnal circadian protective white light spectra.

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Blue light attracts nocturnally migrating birds

The Condor ◽

10.1093/condor/duaa002 ◽

2020 ◽

Vol 122 (2) ◽

Author(s):

Xuebing Zhao ◽

Min Zhang ◽

Xianli Che ◽

Fasheng Zou

Keyword(s):

Blue Light ◽

Field Experiments ◽

Red Light ◽

Light Pollution ◽

Artificial Light ◽

Light Sources ◽

Rapid Urbanization ◽

Phototactic Response ◽

Migrating Birds ◽

The Impact

Abstract Light pollution is increasing and artificial light sources have great impacts on animals. For migrating birds, collisions caused by artificial light pollution are a significant source of mortality. Laboratory studies have demonstrated that birds have different visual sensitivities to different colors of light, but few field experiments have compared birds’ responses to light of different wavelengths. We used 3 monochromatic lights (red, green, and blue) and polychromatic yellow light to study the impact of wavelength on phototaxis at 2 gathering sites of nocturnally migrating birds in Southwest China. For both sites, short-wavelength blue light caused the strongest phototactic response. In contrast, birds were rarely attracted to long-wavelength red light. The attractive effect of blue light was greatest during nights with fog and headwinds. As rapid urbanization and industrialization cause an increase in artificial light, we suggest that switching to longer wavelength lights is a convenient and economically effective way to reduce bird collisions.

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Investigation on optical integration between LED Mid-IR light sources and Si-based waveguides for sensing applications

Journal of Physics Conference Series ◽

10.1088/1742-6596/2145/1/012056 ◽

2021 ◽

Vol 2145 (1) ◽

pp. 012056

Author(s):

Pawaphat Jaturaphagorn ◽

Papichaya Chaisakul ◽

Nattaporn Chattham ◽

Pichet Limsuwan

Keyword(s):

Integrated Circuits ◽

Light Source ◽

Light Emitting Diode ◽

Coupling Scheme ◽

Light Sources ◽

Optical Coupling ◽

Led Light ◽

Carbon Dioxide Gas ◽

Sensing Applications ◽

Ir Light

Abstract Research on mid-IR silicon-based waveguides has recently received strong interest. Particularly, this paper focuses on one of the critical issues in micron-scale photonic integrated circuits, which is to efficiently couple a mid-IR LED (light emitting diode) light source to an external micron-scale waveguide. The optical coupling scheme is crucial for the exploitation of LED light sources in waveguide-based spectroscopic sensing applications. This paper reports optical coupling scheme between an LED mid-IR light source and a silicon rich silicon nitride (SiN) waveguide that could enable the use of LED-based light sources. Finally, the detection limit of the investigated device for carbon dioxide gas detection is calculated.

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Effects of Different LED Light Recipes and NPK Fertilizers on Basil Cultivation for Automated and Integrated Horticulture Methods

Applied Sciences ◽

10.3390/app11062497 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2497

Author(s):

Silvia Barbi ◽

Francesco Barbieri ◽

Alessandro Bertacchini ◽

Luisa Barbieri ◽

Monia Montorsi

Keyword(s):

Controlled Release ◽

Growth Parameters ◽

Light Emitting Diode ◽

Substantial Improvement ◽

Fresh Mass ◽

Light Sources ◽

Npk Fertilizers ◽

Led Light ◽

Deep Blue ◽

Led Lights

This study aims to optimize the conditions for “Genovese” basil (Ocimum Basilicum) germination and growth in an indoor environment suitable for horticulture through a synergic effect of light and fertilizers addition. In fact, several studies determined that specific light conditions are capable of enhancing basil growth, but this effect is highly dependent on the environmental conditions. In this study, the effect of different light sources was determined employing a soil with a negligible amount of fertilizer, demonstrating substantial improvement when light-emitting diode (LED) lights (hyper red and deep blue in different combinations) were applied with respect to daylight (Plants height: +30%, Total fresh mass: +50%). Thereafter, a design of experiment approach has been implemented to calculate the specific combination of LED lights and fertilizer useful to optimize the basil growth. A controlled-release fertilizer based on nitrogen, phosphorus, and potassium (NPK) derived from agro-residues was compared with a soil enriched in macronutrients. The results demonstrate significant improvements for the growth parameters with the employment of the controlled-release NPK with respect to enriched soil combined with a ratio of hyper red and deep blue LED light equal to 1:3 (Total fresh mass: +100%, Leaves number: +20%).

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A Practical Method to Design Reflector-Based Light-Emitting Diode Luminaire for General Lighting

Advances in OptoElectronics ◽

10.1155/2018/7138592 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10

Author(s):

Jinren Yan

Keyword(s):

Light Emitting Diode ◽

Spherical Surface ◽

Target Surface ◽

Practical Method ◽

Optical Simulation ◽

Light Sources ◽

Aspheric Surface ◽

Light Emitting ◽

Led Light ◽

Spherical Reflector

A reflector-based light-emitting diode (LED) luminaire structure that can achieve a large cut-off angle for general lighting is presented in this work. The proposed lighting unit mainly consists of a spherical reflector and a primary packaging lens that contains an aspheric surface and a spherical surface. The light rays emitted from the LED light source are well controlled by the spherical reflector and the aspheric surface of the lens for the purpose of obtaining a uniform illumination on the target surface. Both the ideal Lambertian LED and non-Lambertian LED light sources were employed to validate the proposed structure and the performance of the designed lighting units was analyzed by optical simulation. The results show that the light utilization efficiencies and the estimated uniformities are 92.96% and 91.11% for ideal Lambertian LED-based lighting unit and 93.31% and 91.64% for non-Lambertian LED-based lighting unit, respectively. Further analysis shows that the tolerances of horizontal, vertical, and rotational deviation of the both lighting units were about 2.0 mm, 1.0 mm, and 1.0°, respectively.

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Comparison between the UV and X-ray Photosensitivities of Hybrid TiO2-SiO2 Thin Layers

Materials ◽

10.3390/ma13173730 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3730

Author(s):

Maxime Royon ◽

Francis Vocanson ◽

Damien Jamon ◽

Emmanuel Marin ◽

Adriana Morana ◽

...

Keyword(s):

Refractive Index ◽

Optical Sensors ◽

Light Emitting Diode ◽

Sol Gel ◽

Dip Coating ◽

Thin Layers ◽

Light Sources ◽

X Rays ◽

X Ray ◽

The Impact

The photo-induced effects on sol–gel-based organo TiO2-SiO2 thin layers deposited by the dip-coating technique have been investigated using two very different light sources: A light-emitting diode (LED) emitting in the UV (at 365 nm, 3.4 eV) and an X-ray tube producing 40 keV mean-energy photons. The impact of adding a photo-initiator (2,2-dimethoxy-2-phenylacetophenone-DMPA) on the sol–gel photosensitivity is characterized namely in terms of the photo-induced refractive index measured through M-line spectroscopy. Results show that both silica-titania sol–gel films with or without the photo-initiator are photosensitive to both photon sources. The induced refractive index values reveal several features where slightly higher refractive indexes are obtained for the sol–gel containing the photo-initiator. UV and X-ray-induced polymerization degrees are discussed using Fourier-transform infrared (FTIR) spectroscopy where the densification of hybrid TiO2-SiO2 layers is related to the consumption of the CH=C groups and to the decomposition of Si-OH and Si-O-CH3 bonds. X-rays are more efficient at densifying the TiO2-SiO2 inorganic and organic network with respect to the UV photons. Hard X-ray photolithography, where no cracks or damages are observed after intense exposition, can be a promising technique to design submicronic-structure patterns on TiO2-SiO2 thin layers for the building of optical sensors.

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