scholarly journals Analysis and Recommendations for LED Catastrophic Failure Due to Voltage Stress

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 540
Author(s):  
Shimi Sudha Letha ◽  
Math H. J. Bollen ◽  
Sarah K. Rönnberg
Keyword(s):  
Service Life ◽  
Lower Energy ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Led Lighting ◽  
Voltage Quality ◽  
University Of Technology ◽  
Voltage Stress ◽  
Different Types ◽  
The One

Light-emitting diode (LED) lighting has, compared to other types of lighting, a significantly lower energy consumption. However, the perceived service life is also important for customer satisfaction and here there is a discrepancy between customers’ experience and manufacturers’ statements. Many customers experience a significantly shorter service life than claimed by the manufacturers. An experiment was carried out in the Pehr Högström Laboratory at Luleå University of Technology in Skellefteå, Sweden to investigate whether voltage disturbances could explain this discrepancy. Over 1000 LED lamps were exposed to high levels of voltage disturbances for more than 6000 h; the failure rate from this experiment was similar to the one from previous experiments in which lamps were exposed to normal voltage. The discrepancy thus remains, even though some possible explanations have emerged from the project’s results. The lamps were exposed to five different types of voltage disturbances: short interruptions; transients; overvoltage; undervoltage; and harmonics. Only overvoltage resulted in failure of the lamps, and only for a single topology of lamp. A detailed analysis has been made of the topology of lamps that failed. This lamp type contains a different internal electronics circuit than the other lamp types. Failures of the lamps when exposed to overvoltage are due to the heat development in the control circuit increasing sharply when the lamps are exposed to a higher voltage. Hence, it is concluded that there are lamps that are significantly more sensitive to voltage disturbances than other lamp types. Manufactures need to consider the voltage quality that can be expected at the terminal of the lamp to prevent failure of lamps due to voltage disturbances. This paper therefore contains recommendations for manufacturers of lighting; the recommendations describe which voltage disturbances lamps should cope with.

Analysis of Modified Current Controller and its Implementation in Automotive LED

2017 ◽  
Vol 6 (04) ◽  
pp. 01-06
Author(s):  
Prof. Bhushan Thakre, Dr. R.M Thakre
Keyword(s):  
Supply Voltage ◽  
Light Emitting Diode ◽  
Control Voltage ◽  
Process Technology ◽  
Light Emitting ◽  
Led Lighting ◽  
Current Controller ◽  
Dimming Control ◽  
Simulation Purpose ◽  
The One

A novel highly dimmable current controller which is a linear one is employed in the application of low power automotive is discussed here. Light Emitting Diode is the one which drives current that is linearly controlled to decrease the intensity of LED to limit the destruction of the LED and improve its reliability. Although many dimming techniques for LED lighting are available, our proposed method outperforms the existing methods in terms of power consumption and the no. of transistors used in the proposed design. This emits 100mA and decrease the LED current which is going linearly based on the theory of dimming control voltage. Toggling of LED is avoided finally in comparison with the existing system. This circuit is developed in 0.18μm process technology and Cadence ADE with Spectre is employed for simulation purpose. The proposed method utilizes a maximum power of 392.85 mW when the supply voltage is 4V and the control voltage is 4V at the temperature of 27oC.

scholarly journals Continuous LED Lighting Enhances Yield and Nutritional Value of Four Genotypes of Brassicaceae Microgreens

Plants ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 176
Author(s):  
Tatjana G. Shibaeva ◽  
Elena G. Sherudilo ◽  
Alexandra A. Rubaeva ◽  
Alexander F. Titov
Keyword(s):  
Antioxidant Enzymes ◽  
Nutritional Value ◽  
Light Emitting Diode ◽  
Leaf Mass Per Area ◽  
Guaiacol Peroxidase ◽  
Enzymatic Antioxidants ◽  
Light Spectrum ◽  
Light Emitting ◽  
Led Lighting ◽  
Nutritional Benefits

The effect of continuous lighting (CL, 24 h) and light spectrum on growth and nutritional quality of arugula (Eruca sativa), broccoli (Brassica oleracea var. italic), mizuna (Brassica rapa. var. nipposinica), and radish (Raphanus sativus var. radicula) were investigated in growth chambers under light-emitting diode (LED) and fluorescent lighting. Microgreens were grown under four combinations of two photoperiods (16 h and 24 h) providing daily light integral (DLI) of 15.6 and 23.3 mol m−2 day−1, correspondingly) with two light spectra: LED lamps and fluorescent lamps (FLU). The results show that fresh and dry weights as well as leaf mass per area and robust index of harvested arugula, broccoli, mizuna, and radish seedlings were significantly higher under CL compared to 16 h photoperiod regardless of light quality. There were no visible signs of leaf photodamage. In all CL-treated plants higher chlorophyll a/b and carotenoid-to-chlorophyll ratios were observed in all plants except mizuna. CL treatment was beneficial for anthocyanin, flavonoid, and proline accumulation. Higher activities of antioxidant enzymes (catalase, superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase) were also observed in CL-treated plants. In most cases, the effects were more pronounced under LED lighting. These results indicate that plants under mild oxidative stress induced by CL accumulated more non-enzymatic antioxidants and increased the activities of antioxidant enzymes. This added nutritional value to microgreens that are used as functional foods providing health benefits. We suggest that for arugula, broccoli, mizuna, and radish, an LED CL production strategy is possible and can have economic and nutritional benefits.

scholarly journals New wavelength calibration of the HARPS spectrograph

2019 ◽  
Vol 629 ◽  
pp. A27 ◽  
Author(s):  
A. Coffinet ◽  
C. Lovis ◽  
X. Dumusque ◽  
F. Pepe
Keyword(s):  
Radial Velocity ◽  
Frequency Comb ◽  
Light Emitting Diode ◽  
Laser Frequency ◽  
Wavelength Calibration ◽  
Light Emitting ◽  
Before And After ◽  
Doppler Spectroscopy ◽  
One Year ◽  
The One

Context. Doppler spectroscopy has been used in astronomy for more than 150 yr. In particular, it has permitted us to detect hundreds of exoplanets over the past 20 yr, and the goal today of detecting Earth-like planets requires a precision around 0.1 m s−1 or better. Doppler spectroscopy has also been and will be of major importance for other studies such as the variability of fundamental constants and cosmological studies. For all these applications, it is crucial to have the best possible wavelength calibration. Despite the fact that the HARPS spectrograph has been operational at the 3.6-m ESO telescope for more than 15 yr, and that it provides among the most precise Doppler measurements, improvements are still possible. One known problem, for instance, is the non-fully regular block-stitching of the charge-coupled devices (CCDs), which in some cases introduces one-year period parasitic signals in the measured radial velocity. Aims. The aim of the presented work is to improve the wavelength calibration of the HARPS spectrograph to push further its planet-detection capabilities. Methods. The properties of the CCD stitching-induced pixel-size anomalies were determined with light-emitting-diode (LED) flat-field frames, and then a physical, gap-corrected map of the CCDs is used for the fitting model of the spectral orders. We also used a new thorium line list, based on much higher-accuracy measurements than the one used up to now. We derive new wavelength solutions for the 15 yr of HARPS data, both before and after the fibre upgrade that took place in 2015. Results. We demonstrate that we do indeed correct the gap anomalies by computing the wavelength solutions of laser frequency comb exposures, known to have a very low dispersion, both with and without taking the gap correction into account. By comparing the rms of the most stable stars of the HARPS sample, we show that we globally decrease the radial velocity (RV) dispersion of the data, especially for the data acquired after the change of fibres of 2015. Finally, the comparative analysis of several individual systems shows that we manage to attenuate the periodogram power at one year in most cases. The analysis of the RVs derived from individual stellar lines also shows that we indeed correct the stitching-induced RV variation. Conclusions. This improved calibration of the HARPS spectrograph allows to go deeper in the search for low-amplitude radial-velocity signals. This new calibration process will be further improved by combining the thorium calibration spectra with laser frequency comb and Fabry–Perot calibration spectra, and this will not only be used for HARPS but notably also for HARPS-N and the new ESPRESSO spectrograph.

scholarly journals Optimized LED-Integrated Agricultural Facilities for Adjusting the Growth of Water Bamboo (Zizania latifolia)

2020 ◽  
Vol 10 (4) ◽  
pp. 1330
Author(s):  
Vincent K. S. Hsiao ◽  
Teng-Yun Cheng ◽  
Chih-Feng Chen ◽  
Hao Shiu ◽  
Yong-Jin Yu ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Winter Season ◽  
Lighting System ◽  
Zizania Latifolia ◽  
Light Emitting ◽  
Led Lighting ◽  
Led Light ◽  
Bamboo Leaves

We investigated a light emitting diode (LED) lighting system applied to a water bamboo field during winter season at night, and the results indicated that this lighting system can prevent the stunting of water bamboo leaves and further assist its growth. Compared with previous LED systems, in which the LED bulbs were placed directly above water bamboo leaves, our LED lighting system presents the benefit of easy handling during harvest. To prevent the inhomogeneous coverage of LED light patterns, a new design of LED lenses was also incorporated.

Design of Light Emitting Diodes (LEDs) Lighting System and Its Application in Garden Landscape Decoration

2020 ◽  
Vol 15 (6) ◽  
pp. 734-742
Author(s):  
Hailiang Liu ◽  
Jiade Cheng ◽  
Asnidar Hanim Yusuf
Keyword(s):  
Control System ◽  
Large Scale ◽  
Light Emitting Diode ◽  
Image Data ◽  
Junction Temperature ◽  
Lighting System ◽  
Light Emitting ◽  
Led Lighting ◽  
Arm Processor ◽  
Control Node

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.

scholarly journals Data Communication Security Issues of Wi-Fi over Li-Fi

2019 ◽  
Vol 8 (3) ◽  
pp. 1977-1981
Keyword(s):  
Light Emitting Diode ◽  
Denial Of Service ◽  
Data Communication ◽  
Electrical Signal ◽  
Visible Light Communications ◽  
Light Emitting ◽  
Security Issues ◽  
The One ◽  
Audio Video ◽  
Led Lights

Visible Light Communications (VLC) system is called Light Fidelity One such example, analog data is passed to a LED (Light-Emitting Diode) bulb (using signal processing technology), after that it transmits data (which is implanted in its beam) to the detector or photodiode. The small commutes in the brisk feeble of LED bulbs is modulated by the receiver circuit into electrical signal. The signal is then reversed into a duplex data runnel that could be recognized in the same way that of audio, video and web programs that run on devices that has internet enabled. Wi-Fi is vulnerable to breaches involving various security issues such as Rouge Access Points, Denial of Service, Wireless Trespasser, Data Interruption, End point attacks etc. To overcome such restrictions, this paper proposes application level substructure for data communication using Li-Fi (Light Fidelity) Technology. By using LED lights as a transmission medium, the indoor wireless communication is achieved in much faster rate than the one WiFi (Wireless Fidelity) can provide.

scholarly journals Lifetime and optical analyses of LED lamps

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Emerson Roberto Santos ◽  
Hélio Akira Furuya ◽  
Elvo Calixto Burini Junior
Keyword(s):  
Light Emitting Diode ◽  
The Other ◽  
Optical Characteristics ◽  
Integrating Sphere ◽  
Initial Moment ◽  
Direct Relation ◽  
Light Emitting ◽  
Elapsed Time ◽  
The One

In this study, optical and lifetime analyses of commercial light-emitting diode (LED) lamps were carried out with the objective to better understand these characteristics. Lamps of different manufacturers and powers were used: Ourolux of 9 watts, Kian of 9 watts, Black+Decker of 9 watts, FLC of 8 watts, Galaxy of 7 watts and Brilia of 7 watts. These LED lamps remained on by 24 hours/day for 4,291.16 hours. Illuminance measurements were analyzed once a week by each lamp inside the integrating sphere with a sensor of lux meter coupled. Results showed decrease of illuminance by elapsed time, due to the degradation. Results of the illuminance obtained between the initial moment of the experiment and the final one were calculated, revealing degradation of 19% to Ourolux, 20% to FLC, 26% to Black+Decker, 28% to Kian, 29% to Galaxy and 33% to Brilia. This study suggests that the diffusers can have different transmittance values interfering on the illuminance, since the FLC LED lamp presented illuminance with highest values than the other LED lamps tested with similar electrical and optical characteristics. This experiment showed that the nominal power of the LED lamp has no direct relation to the illuminance and, comparing the lifetime, the LED lamp manufactured by Black+Decker was the only one to reach 5,521 hours, that is a lifetime much shorter than the one described at the packages (25,000 hours) for all LED lamps tested

scholarly journals Upward LED Lighting from the Base Suppresses Senescence of Lower Leaves and Promotes Flowering in Indoor Rose Management

HortScience ◽  
2021 ◽  
pp. 1-7
Author(s):  
Namiko Yamori ◽  
Yoriko Matsushima ◽  
Wataru Yamori
Keyword(s):  
Leaf Senescence ◽  
Light Emitting Diode ◽  
Plant Management ◽  
Indoor Environments ◽  
Flower Buds ◽  
Flower Bud ◽  
Light Emitting ◽  
Led Lighting ◽  
Dim Light ◽  
Supplemental Lighting

In indoor environments such as hotels, the light intensity is generally insufficient for managing plants, and flower buds often fail to open. Lamps placed above (downward lighting) take up space. We assessed the applicability of lighting from underneath (upward lighting) for the indoor management of roses. We grew plants indoors in dim light for 2 weeks under three conditions: 1) without supplemental lighting, 2) with downward light-emitting diode (LED) lighting, and 3) with LED lighting. We quantified photosynthetic components (chlorophyll and rubisco) and the maximum quantum yield of photosystem II (Fv/Fm, an indicator of plant health) to determine the effects of each treatment on the quality and photosynthetic abilities of the leaves. We determined the ratios of dead and opened flower buds to elucidate the effects of supplemental lighting on flower bud maturation. Management without supplemental lighting decreased the number of flowers and resulted in lower-leaf senescence. Downward LED lighting promoted blooming but also resulted in lower-leaf senescence. However, upward LED lighting promoted blooming and maintained the photosynthetic abilities of the leaves, including the lower leaves. This study shows a strong case for using upward LED lighting in appropriate settings for indoor plant management and LED-based horticulture.

Thermal Performance of Domestic Replacement A19 LED Lighting Products

2016 ◽  
Author(s):  
Thomas Storey ◽  
Robin Rackerby ◽  
Heather Dillon ◽  
Lydia Gingerich
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Heat Dissipation ◽  
Cooling System ◽  
Light Emitting Diode ◽  
Research Process ◽  
Light Emitting ◽  
Led Lighting ◽  
Proper Design ◽  
The Cost

In an effort to create a Light Emitting Diode (LED) lighting system that is as efficient as possible, the heat dissipation system must be accurately measured for proper design and operation. Because LED lighting technology is new, little optimization has been performed on typical cooling system required for most A19 replacement products. This paper describes the research process for evaluating the thermal performance of over 15 LED lighting products and compares their performance to traditional lighting sources, namely incandescent and compact fluorescent (CFL). This process uses radiation and convection to model typical cooling mechanisms for domestic A19 type replacement LED products. The A19 products selected for this investigation had input wattages ranging between 7 to 60 Watts, with outputs ranging from 450 to 1100 lumens. The average LED tested dissipated 43% (± 5%) of the total heat generated in the lighting product through the heat exchanger. The best thermal performance was observed in an LED product that dissipated approximately 58% of the total product heat through the heat exchanger. Results indicate that significant improvements to the current LED heat exchanger designs are possible, which will help lower the cost of future LED products, improve performance, and reduce the environmental footprint of the products.

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