scholarly journals Calculation of Net Emission Coefficient for High Intensity Discharge Lamps

2020 ◽  
pp. 80-86
Author(s):  
Rawan Al Youssif ◽  
Antoine Sahab ◽  
Georges Zissis ◽  
Walid Malaeb ◽  
Mohamad Hamady
Keyword(s):  
High Intensity ◽  
Radiation Transport ◽  
Ultra Violet ◽  
Small Cells ◽  
Light Sources ◽  
Emission Coefficient ◽  
Uv Spectrum ◽  
Light Emitting ◽  
Net Emission Coefficient ◽  
Basic Equations

There is still great interest in studying high intensity discharge (HID) lamps despite the great development of other light sources like light emitting diodes (LEDs). Basic equations and numerical formulations allow calculating important terms such as the net emission coefficient (NEC) that plays an important role in understanding the radiation behaviour of these lamps. These lamps are considered to be at high pressure and the produced plasma was found to be at local thermodynamic equilibrium (LTE). The volume of the lamp is meshed into small cells and the total number of cells represents a compromise between correct results and calculation time. Each cell has its own local absorption and emission coefficient that applies to its position in the discharge. Line profile is calculated by two profiles convolution: one is Lorentz’s and the second one is a quasi-static profile. Ray tracing technique is used to resolve the radiation transport for the visible and ultra violet (UV) spectrum. The NEC is thus calculated and compared with other models for a pure mercury discharge. In addition, additional photometric properties of the lamp are obtained.

Centers for Disease Control-type light traps equipped with high-intensity light-emitting diodes as light sources for monitoring Anopheles mosquitoes

Acta Tropica ◽  
2018 ◽  
Vol 183 ◽  
pp. 61-63 ◽  
Author(s):  
Benedita Maria Costa-Neta ◽  
Abdias Ribeiro Lima-Neto ◽  
Apoliana Araújo da Silva ◽  
Jefferson Mesquita Brito ◽  
João Vitor Castro Aguiar ◽  
...  
Keyword(s):  
Disease Control ◽  
High Intensity ◽  
Light Emitting Diodes ◽  
Light Sources ◽  
Light Traps ◽  
Light Emitting ◽  
Anopheles Mosquitoes ◽  
Centers For Disease Control ◽  
High Intensity Light

scholarly journals Effects of High-Intensity Curing Lights on Microleakage under Bonded Lingual Retainers

2008 ◽  
Vol 78 (6) ◽  
pp. 1084-1088 ◽  
Author(s):  
Asli Baysal ◽  
Tancan Uysal ◽  
Mustafa Ulker ◽  
Serdar Usumez
Keyword(s):  
High Intensity ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Composite Wire ◽  
Mandibular Incisor ◽  
Light Emitting ◽  
Halogen Light ◽  
Significant Difference ◽  
Light Curing ◽  
High Intensity Light

Abstract Objective: To evaluate the effects of high-intensity light curing units (light-emitting diode [LED] and plasma arc curing [PAC]) on the microleakage of flexible spiral wire retainers (FSWRs) at the composite/enamel and composite/wire interfaces. Materials and Methods: Forty-five human mandibular incisor teeth were separated into three groups of 15 teeth. Multistranded PentaOne wire of .0215 inch diameter was bonded to enamel and was cured with three different light curing units: a quartz-tungsten-halogen (QTH) unit and two high-intensity units (ie, LED and PAC). A conventional halogen light served as the control. Samples were sealed with nail varnish, stained with 0.5% basic fuchsine, and sectioned. Transverse sections were evaluated under a stereomicroscope and were scored for microleakage for the composite/enamel and composite/wire interfaces. Statistical analysis was performed by Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction. Results: Little or no microleakage was detected at the composite/enamel interface of the FSWR cured with three different light sources. However, at the composite/wire interface, statistically significant differences were found between the QTH (mean, 1.10 ± 1.05 mm) and high-intensity curing units. The PAC resulted in the greatest amount of microleakage (mean, 2.63 ± 1.49 mm), whereas no statistically significant difference was noted between the PAC and the LED (mean, 2.35 ± 1.28 mm). Conclusion: High-intensity light curing units show statistically significant microleakage at the composite/wire interface and therefore may not be safe for use in bonding FSWRs.

Organic Light Emitting Diodes - Innovative Light Sources

2019 ◽  
pp. 101-107
Author(s):  
Sergei A. Stakharny
Keyword(s):  
Light Source ◽  
Organic Light Emitting Diodes ◽  
Organic Leds ◽  
Light Sources ◽  
High Quality ◽  
Light Emitting ◽  
Organic Light ◽  
Lighting Systems ◽  
Physical Principles ◽  
Prospects Of Application

This article is a review of the new light source – organic LEDs having prospects of application in general and special lighting systems. The article describes physical principles of operation of organic LEDs, their advantages and principal differences from conventional non-organic LEDs and other light sources. Also the article devoted to contemporary achievements and prospects of development of this field in the spheres of both general and museum lighting as well as other spheres where properties of organic LEDs as high-quality light sources may be extremely useful.

scholarly journals Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1477
Author(s):  
Woo-Suk Jung ◽  
Ill-Min Chung ◽  
Myeong Ha Hwang ◽  
Seung-Hyun Kim ◽  
Chang Yeon Yu ◽  
...  
Keyword(s):  
Plant Growth ◽  
In Vitro Culture ◽  
Light Emitting Diodes ◽  
Photosynthetic Pigment ◽  
Antioxidant Properties ◽  
Light Sources ◽  
Light Emitting ◽  
Cell Defense ◽  
Led Irradiation

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.

Electrically driven single microribbon based near-infrared exciton-polariton light-emitting diode

CrystEngComm ◽  
2021 ◽  
Author(s):  
Mingming Jiang ◽  
Fupeng Zhang ◽  
Kai Tang ◽  
Peng Wan ◽  
Caixia Kan
Keyword(s):  
High Performance ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Coherent Light ◽  
Light Emitting ◽  
Exciton Polaritons ◽  
Laser Devices

Achieving electrically-driven exciton-polaritons has drawn substantial attention toward developing ultralow-threshold coherent light sources, containing polariton laser devices and high-performance light-emitting diodes (LEDs). In this work, we demonstrate an electrically driven...

Four color stacked white organic light-emitting diodes utilizing the concept of triplet harvesting

2011 ◽  
Vol 1286 ◽  
Author(s):  
Th. C. Rosenow ◽  
S. Olthof ◽  
S. Reineke ◽  
B. Lüssem ◽  
K. Leo
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Organic Light Emitting Diodes ◽  
Light Sources ◽  
Emission Layer ◽  
Light Emitting ◽  
Organic Light ◽  
Blue Emitters ◽  
Color Rendering ◽  
Triplet Harvesting

ABSTRACTOrganic light-emitting diodes (OLEDs) are developing into a competitive alternative to conventional light sources. Nevertheless, OLEDs need further improvement in terms of efficiency and color rendering for lighting applications. Fluorescent blue emitters allow deep blue emission and high stability, while phosphorescent blue emitter still suffer from insufficient stability. The concept of triplet harvesting is the key for achieving internal quantum efficiencies up to 100 % and simultaneously benefiting from the advantages of fluorescent blue emitters. Here, we present a stacked OLED consisting of two units comprising four different emitters in total. The first unit takes advantage of the concept of triplet harvesting and combines the light emission of a fluorescent blue and a phosphorescent red emitter. The second unit emits light from a single emission layer consisting of a matrix doped with phosphorescent green and yellow emitters. With this approach, we reach white color coordinates close to the standard illuminant A and a color rendering index of above 75. The presented devices are characterized by high luminous efficacies of above 30 lm/W on standard glass substrates without outcoupling enhancement.

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