Artificial Light Sources Research Articles

Evaluation of activated persulfate under real solar light for degradation of organic pollutants: Kinetics, mechanism, and ecotoxicity

Activation of persulfate (PS) under artificial light sources has been extensively studied as PS based advanced oxidation process (AOP) for degradation of organic pollutants. Here, we demonstrate the enhanced photodegradation of organic pollutants under real sunlight (Sun) in presence of persulfate (PS), (Sun/PS system). Sun/PS caused complete degradation of acid orange (AO7, a colored-dye pollutant), with pseudo-first-order rate constant value (kobs (AO7)) of 0.052 min−1 (sunlight dosage, Qlight 3.9–5.6 kJ/L and 58.3–64.8 kJ/L in the UV range 300–400 nm and visible range 400–800 nm respectively, AO7 = 2 mg/L (5.7 µM), PS = 0.6 mM). In contrast, AO7 degradation was incomplete under Sun alone (0.2 %), and PS alone (1.6 %). Moreover, Sun/PS caused 91 % reduction of total organic carbon (mineralization) within 240 min. Radical scavenging and ESR results confirmed the formation of SO4.− and HO. in Sun/PS system, revealing PS activation by Sun enhances degradation, and mineralization of AO7. Other pollutants such as, acetaminophen (AAP, a colorless pharmaceutical contaminant), and, Malachite Green (MG, a carcinogenic pollutant), were effectively degraded, and mineralized by Sun/PS system in comparison to Sun and PS alone. Moreover, Aliivibrio fischeri (A. fischeri) bioluminescent assay reveals AO7 and AAP pollutants were moderately toxic while, MG was highly toxic. Importantly, the toxicity of these pollutants was removed after Sun/PS treatment. The present findings on evaluation of Sun/PS system highlight, Sun/PS may be applied as an activated PS based AOP for water treatment to remove organic pollutants, and it would be useful as a clean, low-cost approach for resource poor environment but having abundant Sun.

Briefly Analyze the Impact of Artificial Light Sources on Human Health—Take Zhuqiang Artificial Sunlight Lamp as an Example

Briefly Analyze the Impact of Artificial Light Sources on Human Health—Take Zhuqiang Artificial Sunlight Lamp as an Example

Study of the differences among hyperspectral estimation models under different measurement light source conditions

ABSTRACT In hyperspectral remote sensing measurements, the spectral effective information extracted under different measurement light source conditions will produce differences, which in turn affects the robustness of the constructed models. Therefore, it is important to study the differences between hyperspectral estimation models under different measurement light source conditions to construct a general hyperspectral model of vegetation parameters under different light source conditions. In this paper, hyperspectral models are constructed from artificial and natural light sources, and the hyperspectral reflectance and the corresponding SPAD values of artificial and natural light sources under winter wheat, corn and tea tree were measured under the same time period and the same light measurement angle and height. The collected data were used to construct models for the four vegetation indices with better results after screening and to explore how to reduce model variability under different measured light source conditions. The results show that the difference between the artificial light source and natural light source models is significant (the coefficient of determination R2 is significantly different between the artificial light source and natural light source models), and the influence of different light sources on the construction of hyperspectral estimation models can be reduced by selecting vegetation indices. The linear regression equation model constructed by NDVI can effectively reduce the influence of different light sources on the construction of SPAD hyperspectral models and make the model more general. This study can provide new ideas and methods to investigate the differences in spectral models under different measurement light sources.

Hybrid solar lightning system for home lightning

The use of renewable energy is becoming more prevalent in today’s world. The study investigates a hybrid system for interior illumination at a workplace that blends natural light (daylight) with artificial light sources (a conventional system). A sun-tracking Parabolic Concentrator and Fiber Optic Cables device collects Solar Irradiance in the form of light. This technique is beneficial in terms of energy savings, economic efficiency, human health, and reduces environmental emissions. The solar hybrid day lighting using fiber optics can meet the required load demand in a cost-effective way, potentially lowering traditional energy costs for electricity. Thus, the fiber optic cable is the best for the transmission of natural light.

The Potential Energy Saving in Lighting Systems on Campuses in Tropical Areas: A Combination of Natural and Artificial Light

Energy consumption continues to increase and is predicted to increase by up to 30 percent by 2040. Therefore, systematic efforts are needed to reduce energy use, including using natural lighting in lighting systems inside buildings. The object of this study is the library room in the Electrical Engineering Department building, Universitas Andalas, Indonesia, to calculate the potential for energy savings with a lighting automation strategy with dimming control. Measurement of natural light level at three work nodes has been determined for one week as reference data. The shortage of artificial light required, and the electrical energy consumed is calculated by referring to the minimum standards for room lighting intensity. On the basis of each lamp's working hours and power, the potential for energy savings in the lighting system of the object can be determined. This study found that the potential for saving energy consumption for one week at three different nodes was 32.3, 64.2, and 82.8 percent. This study concludes that the maximum value reached 893 lux on Tuesday at 13:00 at node C, and the lowest was 3 lux on Saturday at 15:00 WIB at node A. Node C had an average light intensity of 402.298 lux, and node B had an average of 206.765 lux during the week. In contrast, node A has the lowest lux average, with 87,711 lux in one measurement week. Also, with the combination of natural and artificial light sources with dimming control strategies, the voltage values given to each lamp range from 0 to 180 VAC. Potential savings in energy consumption by combining natural and artificial light with dimming control strategies in the library room with three different nodes (A, B, C) are 32.3, 64.2, and 82.8 percent.

From shallow sea to deep sea: research progress in underwater image restoration

Underwater images play a crucial role in various fields, including oceanographic engineering, marine exploitation, and marine environmental protection. However, the quality of underwater images is often severely degraded due to the complexities of the underwater environment and equipment limitations. This degradation hinders advancements in relevant research. Consequently, underwater image restoration has gained significant attention as a research area. With the growing interest in deep-sea exploration, deep-sea image restoration has emerged as a new focus, presenting unique challenges. This paper aims to conduct a systematic review of underwater image restoration technology, bridging the gap between shallow-sea and deep-sea image restoration fields through experimental analysis. This paper first categorizes shallow-sea image restoration methods into three types: physical model-based methods, prior-based methods, and deep learning-based methods that integrate physical models. The core concepts and characteristics of representative methods are analyzed. The research status and primary challenges in deep-sea image restoration are then summarized, including color cast and blur caused by underwater environmental characteristics, as well as insufficient and uneven lighting caused by artificial light sources. Potential solutions are explored, such as applying general shallow-sea restoration methods to address color cast and blur, and leveraging techniques from related fields like exposure image correction and low-light image enhancement to tackle lighting issues. Comprehensive experiments are conducted to examine the feasibility of shallow-sea image restoration methods and related image enhancement techniques for deep-sea image restoration. The experimental results provide valuable insights into existing methods for addressing the challenges of deep-sea image restoration. An in-depth discussion is presented, suggesting several future development directions in deep-sea image restoration. Three main points emerged from the research findings: i) Existing shallow-sea image restoration methods are insufficient to address the degradation issues in deep-sea environments, such as low-light and uneven illumination. ii) Combining imaging physical models with deep learning to restore deep-sea image quality may potentially yield desirable results. iii) The application potential of unsupervised and zero-shot learning methods in deep-sea image restoration warrants further investigation, given their ability to work with limited training data.

Sensitivity studies of nighttime top-of-atmosphere radiances from artificial light sources using a 3-D radiative transfer model for nighttime aerosol retrievals

Abstract. By accounting for surface-based light source emissions and top-of-atmosphere (TOA) downward lunar fluxes, we adapted the spherical harmonics discrete ordinate method (SHDOM) 3-dimensional (3-D) radiative transfer model (RTM) to simulate nighttime 3-D TOA radiances as observed from the Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) on board the Suomi-NPP satellite platform. Used previously for daytime 3-D applications, these new SHDOM enhancements allow for the study of the impacts of various observing conditions and aerosol properties on simulated VIIRS-DNB TOA radiances. Observations over Dakar, Senegal, selected for its bright city lights and a large range of aerosol optical depth (AOD), were investigated for potential applications and opportunities for using observed radiances containing VIIRS-DNB “bright pixels” from artificial light sources to conduct aerosol retrievals. We found that using the standard deviation (SD) of such bright pixels provided a more stable quantity for nighttime AOD retrievals than direct retrievals from TOA radiances. Further, both the mean TOA radiance and SD of TOA radiances over artificial sources are significantly impacted by satellite viewing angles. Light domes, the enhanced radiances adjacent to artificial light sources, are strong functions of aerosol properties and especially aerosol vertical distribution, which may be further utilized for retrieving aerosol layer height in future studies. Through inter-comparison with both day- and nighttime Aerosol Robotic Network (AERONET) data, the feasibility of retrieving nighttime AODs using 3-D RTM SHDOM over artificial light sources was demonstrated. Our study shows strong potential for using artificial light sources for nighttime AOD retrievals, while also highlighting larger uncertainties in quantifying surface light source emissions. This study underscores the need for surface light emission source characterizations as a key boundary condition, which is a complex task that requires enhanced input data and further research. We demonstrate how quality-controlled nighttime light data from the NASA's Black Marble product suite could serve as a primary input into estimations of surface light source emissions for nighttime aerosol retrievals.

Effect Of Light Spectrum LED Lettuce on IOT-Based Indoor Farming

Lettuce (Lactuca sativa L.) is an economically important crop worldwide and one of the most popular species grown in indoor farming. Lettuce's fast growth and growing cycle make lettuce a model plant to study the interaction between plants and light. The influence of light is one of the fundamental environmental factors for plant growth and development. Light-emitting diodes (LEDs) have higher light efficiency and higher wear efficacy, leading to a reduction in associated heating compared to other artificial lighting sources, such as fluorescent lamps or sodium vapor lamps. This research aimed to determine different responses of the morphological response of lettuce by giving LED light spectrum with a single color spectrum difference and IOT-based temperature and humidity monitoring. This research used a t-student test with a level of 5% on the mean value of the white light spectrum with a yellow light on lettuce plants. The addition of the LED light spectrum produces a different response to the morphological parameters. The addition of the LED spectrum gave a response to the plant height variable, where the provision of a yellow LED light spectrum resulted in plant height which affected lettuce plants

Effect of Various LED Light Qualities, Including Wide Red Spectrum-LED, on the Growth and Quality of Mini Red Romaine Lettuce (cv. Breen).

Recently, LEDs with various light qualities have been used in closed plant factories, and they are known to have different effects on the growth and quality of crops. Therefore, this study was conducted to investigate the change in growth and quality in mini red romaine lettuce using LEDs with various light qualities. Wide red spectrum (WRS)-LEDs, blue (B)-LEDs, blue + red (BR)-LEDs, red (R)-LEDs, and white (W)-LEDs were used as the artificial light sources. Regarding growth, the R-LED treatment showed the most positive effect, but the leaf shape was not normal and the Hunter b* value was not suitable because it was higher than that of the other treatments. The Hunter a*, SPAD, and NDVI values of the B- and BR-LED treatments were effective, but this was not the case for those of the R- and W-LED treatments. The anthocyanin reflectance index 1 (ARI1) was 20 times higher in the B-LED treatment than in the R-LED treatment, and the ascorbic acid content was the highest in the WRS-LED treatment. In the sensory evaluation, bitterness and sweetness showed opposite tendencies. Regarding the overall preference, the BR-LED treatment received the highest score. Correlation analysis showed that the bitterness was closely correlated with the anthocyanin content and leaf color. Taken together, BR-LEDs provided a good top fresh weight, dark red leaves, and high anthocyanin and ascorbic acid contents, with the highest overall preference; therefore, BR-LEDs were the most suitable for the cultivation of mini red romaine lettuce.

Effect of LED Illumination Cycle and Carbon Sources on Biofilms of Haematococcus pluvialis in Pilot-Scale Angled Twin-Layer Porous Substrate Photobioreactors.

Light-emitting diodes are increasingly used as artificial light sources in Haematococcus pluvialis cultivation due to the fact of their energy advantages. The immobilized cultivation of H. pluvialis in pilot-scale angled twin-layer porous substrate photobioreactors (TL-PSBRs) was initially performed with a 14/10 h light/dark cycle and showed relatively low biomass growth and astaxanthin accumulation. In this study, the illumination time with red and blue LEDs at a light intensity of 120 µmol photons m-2 s-1 was increased to 16-24 h per day. With a light/dark cycle of 22/2 h, the biomass productivity of the algae was 7.5 g m-2 day-1, 2.4 times higher than in the 14/10 h cycle. The percentage of astaxanthin in the dry biomass was 2%, and the total amount of astaxanthin was 1.7 g m-2. Along with the increase in light duration, adding 10 or 20 mM NaHCO3 to the BG11-H culture medium over ten days of cultivation in angled TL-PSBRs did not increase the total amount of astaxanthin compared with only CO2 addition at a flow rate of 3.6 mg min-1 to the culture medium. Adding NaHCO3 with a 30-80 mM concentration inhibited algal growth and astaxanthin accumulation. However, adding 10-40 mM NaHCO3 caused algal cells to accumulate astaxanthin at a high percentage in dry weight after the first four days in TL-PSBRs.

ULL-SLAM: underwater low-light enhancement for the front-end of visual SLAM

Underwater visual simultaneous localization and mapping (VSLAM), which can provide robot navigation and localization for underwater vehicles, is crucial in underwater exploration. Underwater SLAM is a challenging research topic due to the limitations of underwater vision and error accumulation over long-term operations. When an underwater vehicle goes down, it may inevitably enter a low-light environment. Although artificial light sources could help to some extent, they might also cause non-uniform illumination, which may have an adverse effect on feature point matching. Consequently, the capability of feature point extraction-based visual SLAM systems could only sometimes work. This paper proposes an end-to-end network for SLAM preprocessing in an underwater low-light environment to address this issue. Our model includes a low-light enhancement branch specific with a non-reference loss function, which can achieve low-light image enhancement without requiring paired low-light data. In addition, we design a self-supervised feature point detector and descriptor extraction branch to take advantage of self-supervised learning for feature points and descriptors matching to reduce the re-projection error. Unlike other works, our model does not require pseudo-ground truth. Finally, we design a unique matrix transformation method to improve the feature similarity between two adjacent video frames. Comparative experiments and ablation experiments confirm that the proposed method in this paper could effectively enhance the performance of VSLAM based on feature point extraction in an underwater low-light environment.

TCAD Device Simulation of All-Polymer Solar Cells for Indoor Applications: Potential for Tandem vs. Single Junction Cells.

The utilization of indoor photovoltaics makes it feasible to harvest energy from artificial light sources. Although single-junction indoor photovoltaics have demonstrated exceptional efficacy when using LED lighting, there is still a need for more comprehensive testing of tandem structures. Herein, the first systematic TCAD simulation study on the potential for tandem all-polymer solar cells (all-PSCs) for indoor applications is provided. The presented all-PSCs are based on experimental work in which the top wide bandgap subcell comprises a polymer blend PM7:PIDT, while the bottom narrow bandgap subcell has a polymer blend PM6:PY-IT. Standalone and tandem cells are simulated under AM1.5G solar radiation, and the simulation results are compared with measurements to calibrate the physical models and material parameters revealing PCE values of 10.11%, 16.50%, and 17.58% for the front, rear, and tandem cells, respectively. Next, we assessed the performance characteristics of the three cells under a white LED environment for different color temperatures and light intensities. The results showed a superior performance of the front cell, while a deterioration in the performance was observed for the tandem cell, reflecting in a lower PCE of 16.22% at a color temperature of 2900 K. Thus, an optimized tandem for outdoor applications was not suitable for indoor conditions. In order to alleviate this issue, we propose designing the tandem for indoor lightening by an appropriate choice of thicknesses of the top and bottom absorber layers in order to achieve the current matching point. Reducing the top absorber thickness while slightly increasing the bottom thickness resulted in a higher PCE of 27.80% at 2900 K.

Effects of different artificial photosynthetically active radiation (PAR) sources and intensity on the growth and nutrient uptake in Ulva prolifera and Neopyropia yezoensis

Fluorescent lamps and semiconductor light-emitting diodes (LEDs) lamps are commonly used as artificial light sources in the indoor algae cultivation system. In this study, we tested the effect of two types of fluorescent lamps (T8 and T5) and white LED lamp on the growth, photosynthesis, and nutrient uptake rates of Neopyropia yezoensis and Ulva prolifera under three photosynthetically active radiation (PAR) conditions (80, 150 and 300 μmol photon m2 s−1). White LED and T8 fluorescent light induced the highest and the lowest growth rates, respectively, in both species under each PAR. The effect of T5 fluorescent light on growth rate depends on the species and PAR. Interestingly, the T8 fluorescent light significantly increased the uptake rate of phosphorus under all PARs and nitrogen uptake rate was enhanced under 150 μmol photon m2 s−1 in U. prolifera, which was not observed in N. yezoensis. Our results suggest that white LED lamp is a more economical and efficient artificial light source than fluorescent lamps because of their highest enhancement of growth. The optimal PAR of T5 fluorescent light for growth is lower than T8 fluorescent light in the cultivation of U. prolifera. T8 fluorescent increases phosphorous uptake rate in U. prolifera.

Performance Analysis of Silicon Technologies Photovoltaic Cells Using Artificial Light Source in Different Spectra

Photovoltaic devices have a spectral response that depends directly on the light spectrum wavelength, causing their performance to be significantly modified with the spectral distribution of the incident radiation. It is essential to consider that the spectrum of sunlight varies with the location, climate, season, time of day and even the angle of incident rays. Thus, it is essential to evaluate the behavior of photovoltaic technologies in different light spectrums to obtain the best conditions for the installation of photovoltaic systems and minimize performance losses. From this perspective, there is great difficulty in analyzing the efficiency of these devices in outdoor tests, taking into account specific light spectra since the solar spectrum is very broad. In order to contribute to this aspect, this work proposes the use of a device for conducting indoor experimental tests with artificial light based on power RGB LED to analyze the performance of photovoltaic cells using amorphous, polycrystalline and monocrystalline silicon technology in spectra of specific light. This analysis is performed by obtaining the characteristic curve of the current and voltage of the tested cells and their extracted electrical parameters.

Calculation of Irradiance from Illuminance for Artificial Light Photovoltaics Applications

Many indoor sensors are powered by artificial-light-harvesting photovoltaic (PV) cells. The performance evaluation and application of PV devices require irradiance measurement to determine input power. Standard solar irradiance meters provide measurements calibrated to sunlight spectra and do not have the low-light-level capability needed for indoor applications. Light meters, specifically designed for human visible artificial light applications, measure illuminance. This article describes a low-cost method to calculate irradiance from illuminance measurement of artificial light sources. An application example is provided.

G-C3N4 for Photocatalytic Degradation of Parabens: Precursors Influence, the Radiation Source and Simultaneous Ozonation Evaluation

Graphitic carbon nitride (g-C3N4) is a promising catalyst for contaminants of emerging concern removal applications, especially as a visible-light-driven material. In this study, g-C3N4 catalysts were effectively synthesized through a simple thermal polymerization method, using melamine, urea, and thiourea as precursors to elucidate the influence of these compounds on the final product’s photocatalytic performance. The degradation of a mixture of three parabens was investigated under different types of radiation: two artificial, ultraviolet-A (UVA) and visible LED, and natural sunlight. The urea-based catalyst (UCN) presented better results under all radiation sources, followed by thiourea, and finally, melamine. Among the artificial light sources, the degradation of parabens under UVA was considerably higher than visible—up to 51% and 21%, respectively—using UCN; however, the broader spectrum of natural sunlight was able to achieve the highest removals, up to 92%, using UCN. Comparing artificial radiation sources, UVA lamps presented 45% lower energy consumption and associated costs. Photocatalytic ozonation was tested using UCN and MCN, with UCN once more possessing superior performance and a synergetic effect between photocatalysis and ozonation, with complete removal under 12 min. The use of g-C3N4 was then successfully tested in initial screening and found to be an efficient alternative in more low-cost and feasible solar photocatalysis water treatment.

Insects within bushes assemble and forage closer to artificial light at night

AbstractArtificial light at night (ALAN) has been implicated in the global decline of insect populations. Causal mechanisms contributing to declines remain unclear, however. Here we examine causal factors which could link some declining terrestrial insect populations with ALAN. To do so, we defined the closest and furthest halves of individual bushes according to the nearest source of artificial light. We sampled leaves and invertebrates from both sides to determine herbivory and abundance. First, we observed that, within bushes, leaves were significantly more likely to display herbivory at closer distances to established streetlighting. This may be due to the phenomenon of positive phototaxis in insects (flight to light). Further, insects within bushes were significantly more abundant on the side closest to streetlighting at midnight, but not at midday, when lights are unilluminated. Consequently, we argue that ALAN creates bottom‐up trophic effects, driven by insect light attraction behaviours even at the scale of single plants.

Low-Intensity Visible and Near-Infrared Light-Induced Cell Signaling Pathways in the Skin: A Comprehensive Review

Objective: To describe current knowledge regarding established and putative cell signaling pathways involved in skin photobiomodulation. Background: The skin is the largest and most accessible organ of the body. It is the first line of defense against the external environment, including solar radiation. Among solar rays, visible and infrared non-ionizing photons may reach human skin and trigger a cascade of non-thermal cell signaling pathways called photobiomodulation (PBM). The use of PBM using artificial light sources has been known for more than 50 years, but it has not yet been widely accepted due to uncertainty about the cellular mechanisms of action. However, much knowledge has been gained in this field in recent years, which will be summarized in this review. Methods: An extensive literature review was performed using Medline, Embase, and Google Scholar as research databases to acquire relevant publications in this particular field. Results: A comprehensive description of chromophores, primary and secondary effectors is provided in addition to a visual representation of known and putative cell signaling mechanisms involved in such complex light-skin interactions. Also, a summary of clinical indications of skin PBM, key light parameters, and promising skin applications (local and systemic) are mentioned. Conclusions: In PBM, skin cells are the first to absorb photons, triggering specific cell-signaling pathways through primary and secondary effectors, leading to enhanced cell repair and survival, notably in hypoxic or stressed cells. A better understanding of the mechanisms of action will help us optimize known indications and discover new ones.

A Retrospective of Artificial Lighting from Ancient Times to the Present Day

A retrospective of the origin and development of light sources is given depending on the history of human development and the creation of fundamental sciences: mathematics, physics, and electrical engineering. Four stages of development and creation of artificial light sources in buildings and structures are proposed. A detailed description of the pre-electric period (regular use of fire by the man; the Bronze Age, the middle Ages and modernity) is presented. The second period begins with the opening of the voltaic arc, which can be called the beginning of the electric period. Illustrations of each discovery with lighting of rooms and buildings of the corresponding period are presented. The period of inventions, which led to the beginning of the third, gas lighting period, is described. This period includes, among other things, the combined use of gas lighting devices with electric lighting and combined gas-electric lighting. The fourth period begins at the beginning of the third millennium and continues to the present. During this period new alternative lighting sources appear along with incandescent lamps and gas-electric sources. Lighting engineering is becoming an independent branch of science and is being studied in all universities of our country, which increases the rate of appearance of new inventions and types of calculation. There are such lighting sources as fluorescent and LED lamps and fixtures. At the end of the article, the opinions of scientists on the prospects for the development of artificial lighting according to various criteria are presented. The article is provided with a large number of illustrations for all stages of development.

Effect of Post-harvesting with Different Photoperiods under Artificial Light Sources on Nitrate and Vitamin C Contents in Hydroponic Green Oak Lettuce

Green oak lettuce (Lactuca sativa L.) is a popular vegetable for consumers, but it is concerned about nitrate contamination that may harm human health. However, light can affect nitrate reduction and contribute to the accumulation of vitamin C in vegetables. Therefore, this study focused on the effects of post-harvesting with different photoperiods under artificial light sources on vitamin C and nitrate content in hydroponic green oak lettuce. Green oak lettuces were grown in the NFT system, harvested, and post-harvested under Bulb-LED (Experiment I), Bar-LED (Experiment II), and fluorescent lamp (FL) (Experiment III) for 6, 12, and 24 h photoperiods and replaced the nutrient solution with tap water. The nitrate content was significantly reduced after post-harvesting for 12 h photoperiods under FL (9,012 µg NO3- -N/g dry weight) followed by Bulb-LED (13,985 µg NO3- -N/g dry weight) and 24 h photoperiods for Bar-LED (10,727 µg NO3- -N/g dry weight). Vitamin C content was highest after post-harvesting for 24 h photoperiods under Bar-LED (45.47 µg/ml), followed by Bulb-LED (44.73 µg/ml) and FL (35.40 µg/ml). Post-harvesting with artificial light sources for 12 to 24 h photoperiods can improve hydroponic green oak lettuce quality.