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1
Nik, Sahidah Nik Ahmad, Hanis Mohammad Radzi Nur, and Noor Abdullah Mohd. "Illuminance levels based on different sky conditions by considering daylight harvesting." Indonesian Journal of Electrical Engineering and Computer Science (IJEECS) 19, no. 3 (2020): 1219–25. https://doi.org/10.11591/ijeecs.v19.i3.pp1219-1225.
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Daylight Harvesting Systems (DHS) offer the most effective and significant to reduce energy consumption. In the lighting system, there are various problems which include waste of energy consumption, inappropriate lighting and increasing greenhouse effect. Therefore, the waste of energy consumption should be reduced by controlling the dimming levels of artificial lighting according to the standard thus reducing the greenhouse effect. Hence, this paper considered the daylight adaptive for the lighting system to determine the dimming level and illuminance level for the office room. The simulation has been carried out using DIALux simulation lighting software to simulate the average daylight and average illuminance level with different conditions sky, which is clear, average, and overcast sky. Based on the result, the illuminance level has complied with the European Standard EN12464-1. Furthermore, the presence of daylight and weather conditions plays an essential role in the lighting system. The illuminance and dimming levels are different depending on the time and type of sky condition at that time. Therefore, the daylight adaptive in the lighting system can reduce the use of artificial light in the room.
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Han, Doohee, and Kyujin Lee. "Dimming Level Improvement Method Through Simple Mapping Error Correction Code in Visible Light Communication." Journal of Computational and Theoretical Nanoscience 18, no. 5 (2021): 1453–57. http://dx.doi.org/10.1166/jctn.2021.9610.
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Since the visible light communication (VLC) has to perform the functions of communication and illumination at the same time, a method for communication as well as lighting is needed. In this paper, when text data is transmitted through visible light communication, the level of illumination dimming according to the frequency of occurrence of alphabets in sentences is analyzed, and a method of improving the dimming level and Bit Error Rate (BER) performance through error correction codes generated during data transmission is studied. Visible light communication systems must perform both communication and lighting functions, so not only communication but also a method for the lighting role is needed. When transferring data (transfer text), the frequency of occurrence of alphabets in sentences is different. Depending on the frequency of occurrence of these alphabetic characters, if there are many ‘0’s in the code to be transmitted, the dimming level will be lowered and flicker will occur. Also, when a 1-bit error occurs, the alphabet code itself is changed. To solve this problem, an error correction code using parity bits has been added. Through this, it was confirmed that the overall dimming level and Bit Error Rate (BER) performance were improved. Also, in visible light communication, the function of lighting is closely related to the performance of the overall system. As we have seen above, when there is a continuous zero period, the function of the lighting is severely degraded. This reduces the performance of the entire system, not just the lighting. Therefore, the dimming level and BER performance were improved by improving the performance through the algorithm and error correction code to improve the overall dimming level.
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Han, Doohee, and Kyujin Lee. "Dimming Level Improvement Method Through Simple Mapping Error Correction Code in Visible Light Communication." Journal of Computational and Theoretical Nanoscience 18, no. 5 (2021): 1453–57. http://dx.doi.org/10.1166/jctn.2021.9610.
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Since the visible light communication (VLC) has to perform the functions of communication and illumination at the same time, a method for communication as well as lighting is needed. In this paper, when text data is transmitted through visible light communication, the level of illumination dimming according to the frequency of occurrence of alphabets in sentences is analyzed, and a method of improving the dimming level and Bit Error Rate (BER) performance through error correction codes generated during data transmission is studied. Visible light communication systems must perform both communication and lighting functions, so not only communication but also a method for the lighting role is needed. When transferring data (transfer text), the frequency of occurrence of alphabets in sentences is different. Depending on the frequency of occurrence of these alphabetic characters, if there are many ‘0’s in the code to be transmitted, the dimming level will be lowered and flicker will occur. Also, when a 1-bit error occurs, the alphabet code itself is changed. To solve this problem, an error correction code using parity bits has been added. Through this, it was confirmed that the overall dimming level and Bit Error Rate (BER) performance were improved. Also, in visible light communication, the function of lighting is closely related to the performance of the overall system. As we have seen above, when there is a continuous zero period, the function of the lighting is severely degraded. This reduces the performance of the entire system, not just the lighting. Therefore, the dimming level and BER performance were improved by improving the performance through the algorithm and error correction code to improve the overall dimming level.
4
Kim, Byung Wook. "Secrecy Dimming Capacity in Multi-LED PAM-Based Visible Light Communications." Wireless Communications and Mobile Computing 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/4094096.
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Recently, mobile cloud computing (MCC) has gained a lot of interest for researchers building the next-generation mobile applications. Because unauthorized access may cause serious problems, security and privacy with MCC have become significant issues. This paper addresses the secrecy dimming capacity of secure transmission in MCC over visible light communication (VLC) channels. By obtaining the entropy-maximizing symbol probability of multiple light emitting diode- (LED-) based pulse amplitude modulation (PAM), mathematical analysis of the secrecy dimming capacity of VLC was derived. Simulation results show that the secure transmission ability of multi-LED-based VLC is determined according to the number of activated LEDs and target dimming level. This can be a guideline for practical VLC-based mobile network designers intending to secure wireless transmission and to decide on the number of activated LEDs at target dimming level to operate.
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Chraibi, S., P. Creemers, C. Rosenkötter, EJ van Loenen, MBC Aries, and ALP Rosemann. "Dimming strategies for open office lighting: User experience and acceptance." Lighting Research & Technology 51, no. 4 (2018): 513–29. http://dx.doi.org/10.1177/1477153518772154.
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Sensor-triggered control strategies can limit the energy consumption of lighting by considering the presence of users in the office and dimming lighting down when it is not needed. In multi-user offices, the application of occupancy-based dimming at room level limits the energy saving potential. However, zone- or desk-based dimming may affect the comfort of co-workers due to its dynamics. This paper reports the assessment by 17 participants (30–50 years of age) of occupancy-based dimming in a mock-up office, using different dimming speeds. Participants consisted of co-workers experiencing changes triggered by others, and actors triggering these light changes. While the participants performed an office-based task, the luminaire above the actors’ desk was dimmed from approximately 550 lx to 350 lx (average horizontal illuminance), and vice versa. The participants evaluated the dimming conditions regarding their noticeability and acceptability. The study showed that the noticeability of light changes due to dimming, increases when fading times become shorter. Dimming with a fading time of at least two seconds was experienced as acceptable by more than 70% of the participants. The results of this experiment provide insights to system behaviour that does not compromise user experience while addressing energy efficient use of electric lighting.
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Nowrin, Itisha, M. Rubaiyat Hossain Mondal, Rashed Islam, and Joarder Kamruzzaman. "A Novel OFDM Format and a Machine Learning Based Dimming Control for LiFi." Electronics 10, no. 17 (2021): 2103. http://dx.doi.org/10.3390/electronics10172103.
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This paper proposes a new hybrid orthogonal frequency division multiplexing (OFDM) form termed as DC-biased pulse amplitude modulated optical OFDM (DPO-OFDM) by combining the ideas of the existing DC-biased optical OFDM (DCO-OFDM) and pulse amplitude modulated discrete multitone (PAM-DMT). The analysis indicates that the required DC-bias for DPO-OFDM-based light fidelity (LiFi) depends on the dimming level and the components of the DPO-OFDM. The bit error rate (BER) performance and dimming flexibility of the DPO-OFDM and existing OFDM schemes are evaluated using MATLAB tools. The results show that the proposed DPO-OFDM is power efficient and has a wide dimming range. Furthermore, a switching algorithm is introduced for LiFi, where the individual components of the hybrid OFDM are switched according to a target dimming level. Next, machine learning algorithms are used for the first time to find the appropriate proportions of the hybrid OFDM components. It is shown that polynomial regression of degree 4 can reliably predict the constellation size of the DCO-OFDM component of DPO-OFDM for a given constellation size of PAM-DMT. With the component switching and the machine learning algorithms, DPO-OFDM-based LiFi is power efficient at a wide dimming range.
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Feng, Qi Bin, Hao Tong, and Guo Qiang Lv. "An Adaptive Global LED Backlight Dimming for Contrast Enhancement and Power Reduction." Solid State Phenomena 181-182 (November 2011): 241–44. http://dx.doi.org/10.4028/www.scientific.net/ssp.181-182.241.
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The paper proposes a global backlight dimming algorithm for CR enhancement and power reduction. S-shaped function is involved to help improve CR. Both the backlight dimming level and the turning point grayscale of the s-shaped curve are determined by the histogram of the input image. The pixels with the grayscales more than the turning point are compensated to become brighter and the pixels less than turning point become darker. The simulation results show that the proposed dimming algorithm can improve CR by average 34.95% and reduce power consumption by 11.30%.
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Ahmad, Nik Sahidah Nik, N. H. Radzi, and Mohd Noor Abdullah. "Illuminance levels based on different sky conditions by considering daylight harvesting." Indonesian Journal of Electrical Engineering and Computer Science 19, no. 3 (2020): 1219. http://dx.doi.org/10.11591/ijeecs.v19.i3.pp1219-1225.
Full textAbstract:
Daylight Harvesting Systems (DHS) offer the most effective and significant to reduce energy consumption. In the lighting system, there are various problems which include waste of energy consumption, inappropriate lighting and increasing greenhouse effect. Therefore, the waste of energy consumption should be reduced by controlling the dimming levels of artificial lighting according to the standard thus reducing the greenhouse effect. Hence, this paper considered the daylight adaptive for the lighting system to determine the dimming level and illuminance level for the office room. The simulation has been carried out using DIALux simulation lighting software to simulate the average daylight and average illuminance level with different conditions sky, which is clear, average, and overcast sky. Based on the result, the illuminance level has complied with the European Standard EN12464-1. Furthermore, the presence of daylight and weather conditions plays an essential role in the lighting system. The illuminance and dimming levels are different depending on the time and type of sky condition at that time. Therefore, the daylight adaptive in the lighting system can reduce the use of artificial light in the room.
9
Muruga, A. P. Jaya. "Neural Network Based Dimming Level Control of LED Network." International Journal on Recent and Innovation Trends in Computing and Communication 3, no. 2 (2015): 438–43. http://dx.doi.org/10.17762/ijritcc2321-8169.150203.
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Liu, Rui, and Wensi Wang. "Nonparametric Statistics on Magnetic Properties at the Footpoints of Erupting Magnetic Flux Ropes." Astrophysical Journal 973, no. 1 (2024): 50. http://dx.doi.org/10.3847/1538-4357/ad66bd.
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Abstract It is under debate whether the magnetic field in the solar atmosphere carries neutralized electric currents, in particular, whether a magnetic flux rope (MFR), which is considered the core structure of coronal mass ejections, carries neutralized electric currents. Recently Wang et al. (2023) studied magnetic flux and electric current measured at the footpoints of 28 eruptive MFRs from 2010 to 2015. Because of the small sample size, no rigorous statistical analysis has been done. Here, we include nine more events from 2016 to 2023 and perform a series of nonparametric statistical tests at a significance level of 5%. The tests confirm that there exist no significant differences in magnetic properties between conjugated footpoints of the same MFR, which justifies the method of identifying the MFR footpoints through coronal dimming. The tests demonstrate that there exist no significant differences between MFRs with preeruption dimming and those with only posteruption dimming. However, there is a medium level of association between MFRs carrying substantial net current and those producing preeruption dimming, which can be understood by the Lorentz self-force of the current channel. The tests also suggest that in estimating the magnetic twist of MFRs, it is necessary to take into account the spatially inhomogeneous distribution of electric current density and magnetic field.
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Stamatis, Michael, Nikolaos Hatzianastassiou, Marios-Bruno Korras-Carraca, Christos Matsoukas, Martin Wild, and Ilias Vardavas. "An Assessment of Global Dimming and Brightening during 1984–2018 Using the FORTH Radiative Transfer Model and ISCCP Satellite and MERRA-2 Reanalysis Data." Atmosphere 14, no. 8 (2023): 1258. http://dx.doi.org/10.3390/atmos14081258.
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In this study, an assessment of the FORTH radiative transfer model (RTM) surface solar radiation (SSR) as well as its interdecadal changes (Δ(SSR)), namely global dimming and brightening (GDB), is performed during the 35-year period of 1984–2018. Furthermore, a thorough evaluation of SSR and (Δ(SSR)) is conducted against high-quality reference surface measurements from 1193 Global Energy Balance Archive (GEBA) and 66 Baseline Surface Radiation Network (BSRN) stations. For the first time, the FORTH-RTM Δ(SSR) was evaluated over an extended period of 35 years and with a spatial resolution of 0.5° × 0.625°. The RTM uses state-of-the-art input products such as MERRA-2 and ISCCP-H and computes 35-year-long monthly SSR and GDB, which are compared to a comprehensive dataset of reference measurements from GEBA and BSRN. Overall, the FORTH-RTM deseasonalized SSR anomalies correlate satisfactorily with either GEBA (R equal to 0.72) or BSRN (R equal to 0.80). The percentage of agreement between the sign of computed GEBA and FORTH-RTM Δ(SSR) is equal to 63.5% and the corresponding percentage for FORTH-RTM and BSRN is 54.5%. The obtained results indicate that a considerable and statistically significant increase in SSR (Brightening) took place over Europe, Mexico, Brazil, Argentina, Central and NW African areas, and some parts of the tropical oceans from the early 1980s to the late 2010s. On the other hand, during the same 35-year period, a strong and statistically significant decrease in SSR (Dimming) occurred over the western Tropical Pacific, India, Australia, Southern East China, Northern South America, and some parts of oceans. A statistically significant dimming at the 95% confidence level, equal to −0.063 Wm−2 year−1 (or −2.22 Wm−2) from 1984 to 2018 is found over the entire globe, which was more prevalent over oceanic than over continental regions (−0.07 Wm−2 year−1 and −0.03 Wm−2 year−1, statistically significant dimming at the 95% confidence level, respectively) in both hemispheres. Yet, this overall 35-year dimming arose from alternating decadal-scale changes, consisting of dimming during 1984–1989, brightening in the 1990s, turning into dimming over 2000–2009, and brightening during 2010–2018.
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Zhang, Xi Tiao, Fen Liu, and Guo Qiang Lv. "Research and Evaluation of Local Dimming Algorithm for LED Backlight LCD Display." Applied Mechanics and Materials 321-324 (June 2013): 486–90. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.486.
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Based on the further study on the dynamic dimming algorithms, the Inverse of Mapping Function (IMF) method, the error correction method and the cumulative distribution function (CDF) method are analyzed and applied to get the dimming level in the bottom-lit backlight. 50 typical images are simulated. The power reduction, contrast ratio enhancement, and MSSIM are explored to evaluate the 3 above dimming algorithms, the simulation results show that: IMF method does not apply to the low average luminance images; error correction method is suitable for a wide range of images, but the energy-saving rate is not high; though the energy-saving rate of the CDF method is higher than the other two kinds of algorithms, the image quality has a some kind of distortion.
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Jan, Sana Ullah, Young-Doo Lee, and Insoo Koo. "Modeling and Analysis of DIPPM: A New Modulation Scheme for Visible Light Communications." Journal of Sensors 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/963296.
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Visible Light Communication (VLC) uses an Intensity-Modulation and Direct-Detection (IM/DD) scheme to transmit data. However, the light source used in VLC systems is continuously switched on and off quickly, resulting in flickering. In addition, recent illumination systems include dimming support to allow users to dim the light sources to the desired level. Therefore, the modulation scheme for data transmission in VLC system must include flicker mitigation and dimming control capabilities. In this paper, the authors propose a Double Inverse Pulse Position Modulation (DIPPM) scheme that minimizes flickering and supports a high level of dimming for the illumination sources in VLC systems. To form DIPPM, some changes are made in the symbol structure of the IPPM scheme, and a detailed explanation and mathematical model of DIPPM are given in this paper. Furthermore, both analytical and simulation results for the error performance of 2-DIPPM are compared with the performance of VPPM. Also, the communication performance of DIPPM is analyzed in terms of the normalized required power.
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ZHANG Lei, 张磊, 李亚妮 LI Ya-ni, 陆吕晨 LU Lv-chen, and 吕国强 LV Guo-qiang. "Backlight dimming algorithm based on histogram and dominant gray level." Chinese Journal of Liquid Crystals and Displays 29, no. 6 (2014): 1090–95. http://dx.doi.org/10.3788/yjyxs20142906.1090.
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Yang, Yong, Yunni Chen, Haijun Xiong, et al. "87‐5: AM Mini‐LED Based on LTPS TFT Backplane with over 5000 Dimming Zones and High Driving Bits." SID Symposium Digest of Technical Papers 54, no. 1 (2023): 1238–41. http://dx.doi.org/10.1002/sdtp.16802.
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LCD with Mini‐LED backlight performs high brightness and high contrast ratio. In this paper novel Mini‐LED based on LTPS TFT backplane is proposed for LCD backlight with over 5000 dimming zones and excellent image quality. Moreover, based on special driving circuit, 12‐14 driving bits, that is 4096‐16384 gray level, is achieved, which can improve local contrast ratio of the image. Compared to PM Mini‐LED, AM Mini‐LED shows superior performance on high dimming zone design, fewer LED drivers and improvement of image quality.
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Sikora, Roman, Przemysław Markiewicz, and Andrzej Pawlak. "Prediction of LED luminaire spectral power distribution using a mathematical model developed based on interpolation method." Photonics Letters of Poland 14, no. 4 (2022): 77–79. http://dx.doi.org/10.4302/plp.v14i4.1177.
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LED luminaires with controllable luminous flux are increasingly used, mainly due to the need to reduce electricity consumption, which is the equivalent of improving the energy efficiency of a lighting installation. Changing the dimming level changes the spectral power distribution of the luminaire or light source. Knowledge of dimming characteristics including spectral power distribution relationships provides the opportunity to optimize control algorithms and predict the impact of lighting parameters on the work surface. The paper presents a mathematical model to calculate the spectral power distribution of an LED luminaire for any level of dimming. Two interpolation methods were used to develop the model, fitted by polynomial functions and spline functions. Validation of the model was performed for two values of control voltage-dimming levels. Full Text: PDF ReferencesJ. Silva, J.F.G. Mendes, L.T. Silva, "Assessment Of Energy Efficiency In Street Lighting Design", WIT Transaction on Ecology and the Environment 129, 705 (2010). CrossRef A. Nardelli, E. Deuschle, L.Dalpaz de Azevedo, J. Lorenço Novaes Pessoa, E. Ghisi, "Assessment of Light Emitting Diodes technology for general lighting: A critical review", Renewable and Sustainable Energy Rev. 75, 368 (2017). CrossRef O. Rabaza, D. Gómez-Lorente, F. Pérez-Ocón, A. Peña-García, "A simple and accurate model for the design of public lighting with energy efficiency functions based on regression analysis", Energy 107, 831 (2016). CrossRef S. Raggiunto, A. Belli, L. Palma, P. Ceregioli, M. Gattari, P. Pierleoni, "An Efficient Method for LED Light Sources Characterization", Electronics 8(10), 1089 (2019). CrossRef I. Rachev, T. Djamiykov, M. Marinov, N. Hinov, "Improvement of the Approximation Accuracy of LED Radiation Patterns", Electronics 8, 337 (2019). CrossRef
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Chen, Haiwei, Ruidong Zhu, Ming-Chun Li, Seok-Lyul Lee, and Shin-Tson Wu. "60-1: High Dynamic Range LCD with Pixel-level Local Dimming." SID Symposium Digest of Technical Papers 48, no. 1 (2017): 890–93. http://dx.doi.org/10.1002/sdtp.11771.
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Wang, Yawen, Martin Wild, Arturo Sanchez-Lorenzo, and Veronica Manara. "Urbanization effect on trends in sunshine duration in China." Annales Geophysicae 35, no. 4 (2017): 839–51. http://dx.doi.org/10.5194/angeo-35-839-2017.
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Abstract. There is an ongoing debate on whether the observed decadal variations in surface solar radiation, known as dimming and brightening periods, are a large-scale or solely local phenomenon. We investigated this issue using long-term sunshine duration records from China, which experienced a rapid increase in urbanization during the past decades. Over the period 1960–2013, 172 pairs of urban and nearby rural stations were analyzed. Urban and rural sunshine duration trends show similar spatial patterns during a dimming phase (1960–1989) and a subsequent period during which trends were leveling off (1990–2013). This indicates that rather than local effects, the trends in sunshine duration are on more of a national or regional scale in China. Nevertheless, in the dimming phase, the declining rate of sunshine duration in rural areas is around two-thirds of that in urban areas. The ratio of rural to urban dimming generally increases from a minimum of 0.39 to a maximum of 0.87 with increasing indices of urbanization calculated based on the year 2013. It reaches a maximum when the urbanization level exceeds 50 %, the urban population exceeds 20 million, or the population density becomes higher than 250 person km−2. After the transition into the leveling-off period, sunshine duration trends are no longer significantly affected by urbanization. Meanwhile, the number of laws and regulations related to air pollution and investment in pollution treatment have been increasing in China.
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Ren, Hui, Yan Zhe Li, and Hua Bing Zhang. "Study and Realization of Stage Lighting Console." Applied Mechanics and Materials 336-338 (July 2013): 1582–86. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.1582.
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At present, most of the stage lighting console designs are based on MCU(Micro Control Unit), but its technique advances, information storage and real-time performances are deficient. This paper proposed that using the technique of ARM-Linux can realize the function of lighting console. This technique adopted S3C2440 processor as the main control chip of the hardware. The transmission of dimming data followed the DMX512 agreements. The low-level driver programs were developed under linux2.6.12, it provided interfaces for upper layer application. Testing results show that this system has perfect dimming performance and scalability, which is easy to upgrade. Our design has important theoretical significance and practical value for stage lighting control.
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Venny, Venny, and Endah Setyaningsih. "Perancangan dan Realisasi Automatic Dimming Light." TESLA: Jurnal Teknik Elektro 24, no. 1 (2022): 82. http://dx.doi.org/10.24912/tesla.v24i1.18444.
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Lighting is one of the main aspects that has an important role in production activities, especially in the medium-scale industrial production process. To get optimal lighting performance, a light source is needed that can meet the needs of lighting levels in accordance with the Indonesian National Standard (SNI) regarding lighting for medium-scale industrial workplaces or laboratory rooms of educational institutions. Based on the need for a good lighting system, a system in the form of Automatic dimming light was designed that can be programmed to meet the lighting standards according to SNI. The lamp has a controller design concept that automatically uses a 60 Watt bulb which is able to provide 500 lux lighting at a distance of 40 cm from the table surface. Using the light intensity sensor module to read the light intensity value so that the lighting can be processed by Arduino Uno and then forwarded to the bulb. It aims to provide adequate lighting in accordance with the desired standard. Based on the results of testing the level of light intensity, if the condition of the room is dark, the resulting value will be small, but if the condition of the room is bright, the resulting value will be large.
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Hu, Qi, Xueqing Ma, Huayun He, et al. "Warming and Dimming: Interactive Impacts on Potential Summer Maize Yield in North China Plain." Sustainability 11, no. 9 (2019): 2588. http://dx.doi.org/10.3390/su11092588.
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Global warming and dimming/brightening have significant implications for crop systems and exhibit regional variations. It is important to clarify the changes in regional thermal and solar radiation resources and estimate the impacts on potential crop production spatially and temporally. Based on daily observation data during 1961–2015 in the North China Plain (NCP), the impacts of climate change associated with climate warming and global dimming/brightening on potential light–temperature productivity (PTP) of summer maize were assessed in this study. Results show that the NCP experienced a continuous warming and dimming trend in maize growing season during the past 55 years, and both ATT10 and solar radiation had an abrupt change in the mid-1990s. The period of 2000–2015 was warmer and dimmer than any other previous decade. Assuming the maize growing season remains unchanged, climate warming would increase PTP of summer maize by 4.6% over the period of 1961–2015, which mainly occurred in the start grain filling–maturity stage. On the other hand, as negative contribution value of solar radiation to the PTP was found in each stage, dimming would offset the increase of PTP due to warming climate, and lead to a 15.6% reduction in PTP in the past 55 years. This study reveals that the changes in thermal and solar radiation have reduced the PTP of summer maize in the NCP. However, the actual maize yield could benefit more from climate warming because solar radiation is not a limiting factor for the current low production level.
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Duan, Kai, Jiali Guo, Tiesong Hu, Xianxun Wang, and Yadong Mei. "Assessing the Roles of Terrestrial Stilling and Solar Dimming in Land Surface Drying/Wetting across China." Water 12, no. 7 (2020): 1996. http://dx.doi.org/10.3390/w12071996.
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Decreases in wind speed (i.e., terrestrial stilling) and radiation (i.e., solar dimming) have been identified as important causes of aridity change both globally and regionally. To understand how their roles have varied across different natural and socioeconomic circumstances in China, this study presents a nationwide attribution analysis of land surface drying/wetting across the ten first-level river basins. The results suggest that consistent warming and reductions in relative humidity have significantly enhanced atmospheric evaporative demand and driven the land surface to become drier over the past six decades. However, the widespread terrestrial stilling and solar dimming have largely offset such trends by suppressing evaporation. While spatially varying changes in precipitation were the most influential driver of aridity change over half of the 713 used climate sites, decreasing wind speed and radiation were identified as the dominant cause of wetting at 15% and 13% of the sites, respectively. The impacts of terrestrial stilling and solar dimming were generally more prominent in the north (e.g., the Liao River, Songhuajiang, Hai River, and Huai River basins) and south (e.g., the Southeast, Pearl River, and Yangtze River basins) respectively, which could be associated with the weakening monsoon and intensified anthropogenic disturbances such as ecological restoration, urbanization, and air pollution. We conclude that more attention needs to be paid to the independent and combined climatological impacts of global- and regional-level human activities to develop proactive adaptation strategies of water and land management.
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Riggs, Laramie Nicole. "Adolescent Mothers’ Life Trajectory: What is Dimming Their Futures?" Iris Journal of Scholarship 2 (July 12, 2020): 122–33. http://dx.doi.org/10.15695/iris.v2i0.4829.
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For years, researchers contended that early pregnancy was the primary determinant for poor life outcomes for adolescent mothers (Hayes, 1987, as cited in SmithBattle 2007, p 410). More recently, the flaws in these assumptions have surfaced as theories such as the general systems theory on human behavior are gaining traction. This states that from the individual level (social interactions, cultural beliefs and values, degree of self-efficacy) to the environmental level (family, peer groups, societal norms, social class, economic status, racism), the widening disparity along one’s developmental life course reveals outcomes unique to a person and their experiences (Coie et al., 1993, pp 1014, 1016). The intertwined nature of these systems, each of which will be discussed in further sections, have altered the direction of research concerning sources of poor life outcomes commonly attributed to adolescent motherhood.
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Pinto, German Alfonso Osma, Gabriel Ordóñez Plata, Laura Yazmin Amado Duarte, and Rodolfo Villamizar Mejía. "Control of a Hybrid Illumination System in a Tropical Zone." Applied Mechanics and Materials 704 (December 2014): 368–72. http://dx.doi.org/10.4028/www.scientific.net/amm.704.368.
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This paper presents a control system approach for hybrid illumination of administrative offices (225m2) at an university building located at a tropical zone. The main goal was to minimize the energy consumption of artificial lightings (fluorescent), by taking advantage of the high natural lighting level during a workday (8 a.m. and 6 p.m.). The control system devices used for each office are: presence sensor, dimming photocell and dimming ballasts, all them connected to the Andover Infinet Controller. By means of data analysis and daylight curves, energy consumption and financial savings are determined. Subsequently, the average energy consumption per square meter due to the hybrid lighting in the offices (8.5 kWh/m2/year) and typical illumination of the central campus (27 kWh/m2/year) were compared. It was demonstrated that a reduction of energy consumption of about 70%, 50% by daylighting and 20% by automation was obtained.
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Gao, Zhiwen, Honglong Ning, Rihui Yao, et al. "Mini-LED Backlight Technology Progress for Liquid Crystal Display." Crystals 12, no. 3 (2022): 313. http://dx.doi.org/10.3390/cryst12030313.
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As consumers pursue higher display quality, Mini-LED backlight technology has become the focus of research in the current display field. With its size advantage (100–200 μm), it can achieve one-thousand-level divisional dimming, and it can also be combined with quantum dot technology to greatly improve the contrast, color gamut, dark state and other element of the display performance of LCD displays. Mini-LED backlight technology is undoubtedly the most ideal solution to realize a highly dynamic range display of LCD displays, and has been widely commercialized in many fields such as TVs, tablet computers, notebook computers, and car monitors. This review mainly introduces the efforts made by researchers to eliminate the halo effect, thinning of the backlight module and reducing the backlight power consumption. The application of quantum dot technology in backlight is also presented. We predict that the number of Mini-LED backlight partitions is expected to reach a level of more than 3000 in the future, further utilizing the advantages of the small size in local dimming, but it will also inevitably be challenged by some issues such as power consumption and heat dissipation.
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Kim, Dae Ho, Seung Hyun Jeon, and Jung-Sik Sung. "Direct Illuminance-Contribution-Based Lighting Control for IoT-Based Lighting Systems in Smart Buildings." Sustainability 16, no. 12 (2024): 5054. http://dx.doi.org/10.3390/su16125054.
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With the advent of low-voltage light-emitting diodes (LEDs) and advances in Internet of Things (IoT) technologies, smart buildings have recently become more energy efficient. Nevertheless, the lighting-control system is one of the major sources of electrical energy consumption in commercial buildings. This study proposes a direct illuminance-contribution-based lighting-control framework to reduce the energy of LED luminaires and ensure illuminance for user requirements in smart buildings. Specifically, we designed a direct illuminance-contribution-based lighting-control algorithm (DIC-LCA) using luminaires that are ideally axisymmetric with all light emitted below the horizontal plane and developed a WiFi lighting controller for the IoT-based lighting-control systems in smart buildings. The DIC-LCA can adjust the dimming level by calculating the illuminance based on the line of sight (LOS) distance for energy saving and user satisfaction. After simulation analysis, we prove that energy savings can be achieved by controlling the dimming levels of LED luminaires with high light contribution.
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JOYDEEP MUKHERJEE, BRIJESH YADAV, V.K. SEHGAL, PRAMEELA KRISHNAN, and RAJ KUMAR DHAKAR. "Radiation dimming induced modifications in radiation utilization of wheat (Triticumaestivum) crop." Journal of Agrometeorology 22, no. 3 (2021): 332–38. http://dx.doi.org/10.54386/jam.v22i3.294.
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 Global dimming has many environmental and climatic implications. India has also experienced a steady and continuous radiation dimming since 1960s due to increasing load of dust and aerosol in the atmosphere. Radiation interception, temperature, humidity and wind profile are altered under reduced light condition which are determining factor for crop phenology, leaf area index, biomass production, grain yield and radiation use efficiency of crops.In this experiment, three wheat cultivars (HD 2967, WR 544 and PBW 502) were grown under five solar radiation treatments i.e. R1 (no shading), R2 (20% shading), R3 (35% shading), R4 (50% shading) and R5 (75% shading) during rabi season of 2014-15 and 2015-16 at research farm of ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi to study the effect of radiation dimming on performance of selected wheat cultivars.In both the years the canopy temperature of wheat from crop vegetative stage to maturity was decreased with increase of shading level. The effect of reduced solar radiation significantly decreased the biomass production and yield.The radiation use efficiency (RUE) for biomass was increased due to shading treatments whereas the RUE for yield decreased with radiation reduction.The RUE for yield was the highest for no shading treatment (0.85 and 0.75 g MJ-1 in 2014-15 and 2015-16, respectively). Among the cultivars, the radiation use efficiency for biomass as well as yield was the highest in HD 2967 followed by WR 544 and PBW 502,respectively.
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Li, Xuan, Weifeng Zhao, and Wanli Liu. "Adjustable High-Power Light Emitting Diode Driving Circuit and Its Lighting Application in Sports Venues." Journal of Nanoelectronics and Optoelectronics 18, no. 12 (2023): 1484–92. http://dx.doi.org/10.1166/jno.2023.3539.
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High-power LED not only has the characteristics of energy saving, environmental protection, long service life, and high reliability, but also has the advantages of high light efficiency and large conduction current. According to the characteristics of high-power LED, an adjustable high-power LED driving circuit is designed in this study. The chip adopts the Boost circuit structure driven by constant current, and the output current on a single channel is converted into voltage by using the sampling resistor on the LED path and fed back to the circuit. After passing a mirror current independent of temperature through a resistor, the reference voltage source is obtained by voltage division. When designing the LDO circuit of voltage regulator, modules such as front-end voltage conversion circuit and input under voltage protection circuit are added. When designing the soft start circuit, the output voltage of the soft start replaces the output of the error amplifier and is connected to one end of the PWM comparator. In the design of dimming circuit, PWM dimming technology is adopted, and the DIM pin is connected to low level when there is no PWM signal. In the experiment, the lowest level of soft start is 0.78 V, the highest bit is 1.35 V, and the period is 374.6 us. When VIN = 8 V, the output voltage can be adjusted to 40 V in one period based on soft start, which meets the starting requirements of the driving circuit. When the DIM pin is connected with a PWM dimming signal with a duty ratio of 90% and a frequency of 10 kHz, the output current of the LED light is in a relatively stable state. Applying the designed LED driving circuit to the lighting of sports venues can meet the requirements of daily events and training, and has advantages in energy saving and environmental protection.
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Kim, Jeong-Sik, Won-Been Jeong, Byeong Hun An, and Seung-Woo Lee. "Study on the Effect of Gaze Position and Image Brightness on Peripheral Dimming Technique." Electronics 10, no. 16 (2021): 1896. http://dx.doi.org/10.3390/electronics10161896.
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Here, we study a low-power technique for displays based on gaze tracking, called peripheral dimming. In this work, the threshold levels of the lightness reduction ratio (LRR), where people notice differences in brightness, depending on gaze positions and image brightness, are investigated. A psychophysical experiment with five gaze positions and three image brightness conditions is performed, and the estimated threshold levels are obtained. To investigate the significance of the differences between the threshold levels, the overlap method and the Bayesian estimation (BEST) analysis are performed. The analysis results show that the difference of the threshold levels depending on the conditions is insignificant. Thus, the proposed technique can operate with a constant LRR level, regardless of the gaze position or image brightness, while maintaining the perceptual image quality. In addition, the proposed technique reduces the power consumption of virtual reality (VR) displays by 12–14% on average. We believe that the peripheral dimming technique would contribute to reducing the power of the self-luminous displays used for VR headsets with an integrated eye tracker.
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Li, Baolong, Xiaomei Xue, Qiong Wu, Yang Liu, Guilu Wu, and Zhengquan Li. "Multiuser Transmit Precoding Design for Dimming Compatible Visible Light Communications." Applied Sciences 9, no. 6 (2019): 1147. http://dx.doi.org/10.3390/app9061147.
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In multiuser visible light communication (VLC) systems, many transmit precoding (TPC) techniques have been investigated to suppress multiuser interference. However, these conventional works restrict their modulation to the special case of zero mean, which inherently limits their application to some popular modulations associated with the non-zero mean in VLC, such as pulse position modulation (PPM). Since the modulation with non-zero mean leads to more intricate optical power constraints and design objective functions than the case of zero mean, the TPC design that can support a general modulation is still an open problem. In the paper, we conceive of a general solution of the TPC scheme combined with dimming control for multiuser VLC systems, which is capable of mitigating multiuser interference, while at the same time, achieving the desired dimming level. The proposed scheme is applicable to a wide range of modulations in VLC, such as pulse amplitude modulation (PAM), PPM, and so on. Simulation results demonstrate that the proposed scheme outperforms the traditional pseudo-inverse-based zero-forcing TPC in terms of bit error rate (BER).
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Liu, Hezhen, B. Luo, W. N. Brandt, et al. "A Rapid and Large-amplitude X-Ray Dimming Event in a z ≈ 2.6 Radio-quiet Quasar." Astrophysical Journal 930, no. 1 (2022): 53. http://dx.doi.org/10.3847/1538-4357/ac6265.
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Abstract We report a dramatic, fast X-ray dimming event in a z = 2.627 radio-quiet type 1 quasar, which has an estimated supermassive black hole (SMBH) mass of 6.3 × 109 M ⊙. In the high X-ray state, it showed a typical level of X-ray emission relative to its UV/optical emission. Then its 0.5–2 keV (rest-frame 1.8–7.3 keV) flux dropped by a factor of ≈7.6 within two rest-frame days. The dimming is associated with spectral hardening, as the 2–7 keV (rest-frame 7.3–25.4 keV) flux dropped by only 17%, and the effective power-law photon index of the X-ray spectrum changed from ≈2.3 to ≈0.9. The quasar has an infrared (IR)-to-UV spectral energy distribution and a rest-frame UV spectrum similar to those of typical quasars, and it does not show any significant long-term variability in the IR and UV/optical bands. Such an extremely fast and large-amplitude X-ray variability event has not been reported before in luminous quasars with such massive SMBHs. The X-ray dimming is best explained by a fast-moving absorber crossing the line of sight and fully covering the X-ray emitting corona. Adopting a conservatively small size of 5 GM BH/c 2 for the X-ray corona, the transverse velocity of the absorber is estimated to be ≈0.9c. The quasar is likely accreting with a high or even super-Eddington accretion rate, and the high-velocity X-ray absorber is probably related to a powerful accretion-disk wind. Such an energetic wind may eventually evolve into a massive galactic-scale outflow, providing efficient feedback to the host galaxy.
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Zheng, Ying, Li Wei Huang, Mi Mi Wang, Hui Qin Chen, and Li Zhen Zhang. "The Application of LED Lighting in Museum Exhibition Hall." Applied Mechanics and Materials 644-650 (September 2014): 3449–52. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.3449.
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This paper analyzed the important of lighting in museum from three main aspects, environmental lighting. LED lighting can not only meet requirements of museum lighting, and also has advantage of protecting historical relics and intelligent energy saving. The dimming control of accent lighting is achieved by infrared detection, distance detection of visitor and exhibits. Intelligent lighting and bionic controlling improve the intelligent level of exhibition, protect historical relics effectively, reflect the topic of energy saving and environmental protection.
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Imamovic, A., K. Tanaka, D. Folini, and M. Wild. "Global dimming and urbanization: did stronger negative SSR trends collocate with regions of population growth?" Atmospheric Chemistry and Physics Discussions 15, no. 21 (2015): 31133–51. http://dx.doi.org/10.5194/acpd-15-31133-2015.
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Abstract. Global dimming refers to the decrease in surface solar radiation (SSR) observed from the 1960s to the 1980s at different measurement sites all around the world. It is under debate whether anthropogenic aerosols emitted from urban areas close to the measurement sites are mainly responsible for the dimming. In order to assess this urbanization impact on SSR, we use spatially explicit population density data of 0.08° resolution to construct population indices (PI) at 157 high data quality sites. Our study extends previous population-based studies by incorporating distance-weighting as a simple aerosol diffusion model. We measured urbanization in the surrounding of a site as the PI change form 1960 to 1990 and found no negative correlation with the corresponding SSR trends from 1964 to 1989 for the 92 sites in Europe and Japan. For the 39 sites in China the correlation coefficients are significant at the 5 % level and reach around −0.35, while for the 26 remaining Asian, mostly Russian sites the correlation coefficients reach around −0.55 at the 1 % significance level. Results are similar, when the absolute levels of PIs are taken as an indicator for urbanization. Our findings call into question the existence of an urbanization effect for the sites in Europe and Japan, while such an effect cannot be ruled out for the sites in Asia, especially in Russia.
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Imamovic, Adel, Katsumasa Tanaka, Doris Folini, and Martin Wild. "Global dimming and urbanization: did stronger negative SSR trends collocate with regions of population growth?" Atmospheric Chemistry and Physics 16, no. 5 (2016): 2719–25. http://dx.doi.org/10.5194/acp-16-2719-2016.
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Abstract. Global dimming refers to the decrease in surface solar radiation (SSR) observed from the 1960s to the 1980s at different measurement sites all around the world. It is under debate whether anthropogenic aerosols emitted from urban areas close to the measurement sites are mainly responsible for the dimming. In order to assess this urbanization impact on SSR, we use spatially explicit population density data of 0.08° resolution to construct population indices (PI) at 157 high data quality sites. Our study extends previous population-based studies by incorporating distance-weighting as a simple aerosol diffusion model. We measured urbanization in the surrounding of a site as the PI change from 1960 to 1990 and found no negative correlation with the corresponding SSR trends from 1964 to 1989 for the 92 sites in Europe and Japan. For the 39 sites in China the correlation coefficients are significant at the 5 % level and reach around −0.35, while for the 26 remaining Asian, mostly Russian sites the correlation coefficients reach around −0.55 at the 1 % significance level. Results are similar, when the absolute levels of PIs are taken as an indicator for urbanization. Our findings call into question the existence of an urbanization effect for the sites in Europe and Japan, while such an effect cannot be ruled out for the sites in Asia, especially in Russia.
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Perko, Jurica, Denis Pelin, and Danijel Topic. "ANALYSIS OF OUTDOOR LED LIGHTING’S DIMMING INFLUENCE ON THE PERFORMANCE OF LED DRIVERS." Journal of Energy Technology 10, no. 3 (2024): 33–45. https://doi.org/10.18690/jet.10.3.33-45.2017.
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With the development of new technologies, LEDs (light-emitting diodes) take a significant position in lighting due to their long-life spans and high luminous efficacy, which result in energy and maintenance cost savings. These efficient and innovative light sources require adequate ballast or electronic control gear, also known as LED drivers, for their operation. An LED driver provides appropriate voltage level and current for the operation of LEDs. It converts and rectifies higher voltages of alternating current to lower voltages of direct current and regulates the current flowing through LEDs at a nominal level. There are many advantages and disadvantages to using LEDs, primarily caused by LED circuits and LED drivers. The dimming influence of outdoor LED lighting on the LED driver performance is analysed in this paper, specifically the testing of an LED lighting driver by changing the load level. Results of LED driver efficiency calculated from measured input and output power, output voltage ripple measurements, and total harmonic distortion analysis are shown. Based on the measurement results, significant recommendations and concluding remarks are given.
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Shetty, Divya, Smit Dave, and Siddhant Shah. "Design of Power Supply for RGB LED Based Lamp Source." International Journal of Engineering & Technology 7, no. 4.41 (2018): 55–59. http://dx.doi.org/10.14419/ijet.v7i4.41.24300.
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LED lighting is replacing the conventional lighting system at a very fast pace. RGB LED lighting fixtures offer convenient options of color changes to enhance our environment. The forward characteristics of Red, Green and Blue LED’s indicate the region of control to produce acceptable level of light intensities. As the intensity of light produced by an LED is proportional to its forward current, a suitable region is identified to obtain distinctive colors and to explore the energy saving options. The objective of the paper was to provide a suitable control for dimming in the linear region as well as in the nonlinear region of the diode graph. The RGB LEDs have been powered from three push pull converters. Different control methods have been explored and simulated in PSPICE to switch the LEDs as to produce distinctive colors. Every method seems to have its pros and cons. Eventually Voltage mode control is adopted to provide control over the entire region of the diode graph which includes both linear and nonlinear regions which will serve the purpose of dimming. Accordingly, a multi-colored lamp source using RGB LEDs has been designed and the hardware has been developed.  Â
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Viriezky, Viata, Ova Candra Dewi, and Amardeep M. Dugar. "Lighting Energy Reduction by Optimizing Daylight while Maintaining Cooling Load in Tropical Educational Building, Depok, Indonesia." Journal of Sustainable Architecture and Civil Engineering 32, no. 1 (2023): 145–61. http://dx.doi.org/10.5755/j01.sace.32.1.32267.
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This study aims to reduce the lighting energy consumption in educational buildings while avoiding an increase in cooling load. The Faculty of Engineering building in Universitas Indonesia, Depok, West Java, Indonesia is used as a case study. Daylight optimization can have an impact on lighting energy, which is the largest energy consumer in educational buildings. However, given Indonesia’s tropical climate, daylight leading to heat gain is a concern. Current passive design interventions for controlling daylight and heat gain include light shelves, clerestories, and glazing materials. Daylighting performance is simulated using DIALux software. Results of each intervention are analyzed quantitatively and qualitatively by theories and parameters, namely illuminance level, light uniformity, and overall thermal transfer value (OTTV). Light shelves result in increased uniformity and lower OTTV. Clerestories result in increased average illuminance but higher OTTV. Active intervention with a dimming and grouping system is applied after daylight increases. The combination of passive design interventions and active dimming of electric lights reduces lighting energy with the same OTTV as existing. This study recommends the use of passive and active daylighting strategies considering their effect on the cooling load of buildings.
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Hvass, M. "Darker Cities due to the Energy Crisis and the need for context-specific urban lighting." IOP Conference Series: Earth and Environmental Science 1320, no. 1 (2024): 012015. http://dx.doi.org/10.1088/1755-1315/1320/1/012015.
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Abstract Outdoor lighting has been dimmed or turned off in European municipalities due to the energy crisis. Dimming of outdoor lighting levels led to energy savings, advantages for biodiversity and less light pollution. But the dimming also triggers the basic human assumption that bright light is connected to safety and darkness is connected to fear. To discuss this basic assumption, human experience of dimmed lighting and perceived safety is explored through three case studies. One study explores human experiences of dimmed street lighting during energy crises, the second study investigates dimmed lighting levels around public transportation, and the third study is an example of a context-specific adaptation of street lighting in a residential area. The case studies reveal that dimmed lighting levels, minimized contrasts, and context-specific lighting can lead to an increased connectedness to the spatial and social urban context and an increased feeling of perceived safety. Thus, more light doesn’t always lead to more perceived safety. With a dimmed general lighting level, it is possible to introduce additional subtle lighting layers, structured in a lighting hierarchy to further enhance spatial and social qualities in outdoor contexts in the dark hours. in constructing both.
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Akbar, Fajril, Muhammad Ihsan Ridho, and Dendi Adi Saputra. "The Potential Energy Saving in Lighting Systems on Campuses in Tropical Areas: A Combination of Natural and Artificial Light." Global Journal of Emerging Science, Engineering & Technology 1, no. 1 (2023): 48–57. http://dx.doi.org/10.56225/gjeset.v1i1.20.
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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.
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Kim, HyungTae, EungJoo Ha, KyungChan Jin, and ByungWook Kim. "Optimal Color Lighting for Scanning Images of Flat Panel Display using Simplex Search." Journal of Imaging 4, no. 11 (2018): 133. http://dx.doi.org/10.3390/jimaging4110133.
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A system for inspecting flat panel displays (FPDs) acquires scanning images using multiline charge-coupled device (CCD) cameras and industrial machine vision. Optical filters are currently installed in front of these inspection systems to obtain high-quality images. However, the combination of optical filters required is determined manually and by using empirical methods; this is referred to as passive color control. In this study, active color control is proposed for inspecting FPDs. This inspection scheme requires the scanning of images, which is achieved using a mixed color light source and a mixing algorithm. The light source utilizes high-power light emitting diodes (LEDs) of multiple colors and a communication port to dim their level. Mixed light illuminates an active-matrix organic light-emitting diode (AMOLED) panel after passing through a beam expander and after being shaped into a line beam. The image quality is then evaluated using the Tenenbaum gradient after intensity calibration of the scanning images. The dimming levels are determined using the simplex search method which maximizes the image quality. The color of the light was varied after every scan of an AMOLED panel, and the variation was iterated until the image quality approached a local maximization. The number of scans performed was less than 225, while the number of dimming level combinations was 20484. The proposed method can reduce manual tasks in setting-up inspection machines, and hence is useful for the inspection machines in FPD processes.
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Muhammad, Wasif Umar, B. Yahaya Norzaihar, and B. Baharuddin Zuhairi. "PWM Dimming Control for High Brightness LED Based Automotive Lighting Applications." International Journal of Electrical and Computer Engineering (IJECE) 7, no. 5 (2017): 2434–40. https://doi.org/10.11591/ijece.v7i5.pp2434-2440.
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In recent years, the use of high brightness LEDs has become increasingly accepted as light sources in mainstream vehicles. However, LEDs are semiconductor devices having electrical characteristics completely different to the traditional lamps. The output luminous flux of an LED is determined by the forward current running through it. Therefore they cannot be powered directly from the automotive battery using the conventional driving techniques. They require specialized driving systems which can ensure the optimal flow of current through LEDs, while maintaining the required level of output luminous. This paper discusses the importance of luminous control for LED based lamps. A design example of boost type DC-DC switching converter with pulse width modulated (PWM) dimming control is presented. In the end, simulation has been presented using MATLAB/Simulink simulation package to ensure the system’s performance within the desired parameters
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Jadhav, Ashwin Vijay, P. R. C. Rahul, Vinay Kumar, Umesh Chandra Dumka, and Rohini L. Bhawar. "Spatiotemporal Assessment of Surface Solar Dimming in India: Impacts of Multi-Level Clouds and Atmospheric Aerosols." Climate 12, no. 4 (2024): 48. http://dx.doi.org/10.3390/cli12040048.
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Surface solar radiation (SSR) is a fundamental energy source for an equitable and sustainable future. Meteorology-induced variability increases uncertainty in SSR, thereby limiting its reliability due to its intermittent nature. This variability depends on several meteorological factors, including clouds, atmospheric gases, and aerosol concentrations. This research investigates the detailed impact of different levels of clouds and aerosols on SSR across India. Utilizing satellite data with reanalysis retrievals, the research covers a span of three decades (30 years), from 1993 to 2022. Aerosols contributed to an average attenuation of ~13.33% on SSR, while high, mid, and low cloud conditions showed much stronger impacts, with an attenuation of ~30.80%, ~40.10%, and ~44.30%, respectively. This study reveals an alarming pattern of increasing cloud impact (Cimpact) on SSR in the recent decade, with a significant increasing rate of ~0.22% year−1 for high cloud (HCimpact) and ~0.13% year−1 for mid cloud (MCimpact) impact, while low cloud impact (LCimpact) showed minimal change. The trend of aerosol impact (Aimpact) also showed an average increase of ~0.14% year−1 across all regions. The findings underscore the imperative of considering climatic variables while studying the growing solar dimming. Our findings also will assist policymakers and planners in better evaluating the solar energy resources across India.
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Chung, Jai-Won, Sangsu Park, Seok-Oh Bang, Seong-Sik Yoo, Hyun-Seok Choi, and Jin-Sung Rho. "A Study on Prediction Method for Preferred Dimming Level of Lighting User Using Usage Environment Data." Journal of the Korean Institute of Illuminating and Electrical Installation Engineers 38, no. 1 (2024): 1–7. http://dx.doi.org/10.5207/jieie.2024.38.1.1.
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Sikora, Roman, Przemysław Markiewicz, and Wiesława Pabjańczyk. "Multivariable polynomial fitting of controlled single-phase nonlinear load of input current total harmonic distortion." Open Physics 16, no. 1 (2018): 137–42. http://dx.doi.org/10.1515/phys-2018-0021.
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Abstract The power systems usually include a number of nonlinear receivers. Nonlinear receivers are the source of disturbances generated to the power system in the form of higher harmonics. The level of these disturbances describes the total harmonic distortion coefficient THD. Its value depends on many factors. One of them are the deformation and change in RMS value of supply voltage. A modern LED luminaire is a nonlinear receiver as well. The paper presents the results of the analysis of the influence of change in RMS value of supply voltage and the level of dimming of the tested luminaire on the value of the current THD. The analysis was made using a mathematical model based on multivariable polynomial fitting.
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Waluyo, F. Hadiatna, A. Widura, and P. Setiana. "Development and testing of a light dimming control using arduino uno." IOP Conference Series: Materials Science and Engineering 1212, no. 1 (2022): 012043. http://dx.doi.org/10.1088/1757-899x/1212/1/012043.
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Abstract Increasing population and human needs have an impact on increasing the need for electrical energy. One of them is for lighting needs. Therefore, it is necessary to save the lighting system so that energy consumption is minimum and the need for lighting is optimal, by controlling light dimming. This paper presents an implementation and testing of a dimming light control using an Arduino Uno microcontroller. The circuit used a 12-volt power supply, as a voltage source, to increase to 42 volts, to meet a lamp voltage, through a dc-dc converter. After obtaining the maximum voltage, a MOSFET cut off the voltage according to the desired light or performance level. The duty cycle was directly proportional to the output voltage, using a PWM coding to get the necessary light intensity. Some testing was conducted, including the measurement point shifting to the side. The testing results show that PMW and LDR decreased as the duty cycle increased. Nevertheless, both decreasing are different, the PWM decreased linearly with a gradient of -2.55 and the LDR decreased hyperbolically. While, the illuminance, current, and power rose as the duty cycle increased. The illuminance increased, tent to be saturated, as the power increased. However, the illuminance was reduced as the PWM and LDR increased. The illuminance decreased slightly as the measurement points shifted to the side.
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Akanpinar, Oktay. "Dimming the Lights to Support the Overall Human Wellbeing In An Urban Context." IOP Conference Series: Earth and Environmental Science 1099, no. 1 (2022): 012050. http://dx.doi.org/10.1088/1755-1315/1099/1/012050.
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Abstract In modern times we are exposing ourselves to artificial light sources more than our ancestors were and it is conflicting with learned behaviours developed during the evolutionary process over thousands of years. In this review paper, the effect of this rapid change and possible effects on human wellbeing is questioned. Publications detailing, the health consequences of circadian disruptions and the current stage of global artificial light at night publications have been reviewed to see the level of intrusive lighting at night and to understand the possible connection. The current level of light pollution is mainly questioned as it is reported that the human circadian system and melatonin suppression is more sensitive to a lower level of light than has been previously reported [1]. During the time of review “Light at Night and Circadian” terms used in at Google Chrome search engine and, 24,557 publications were found on Science Direct [2], 17,500 publications were found on Google Scholar [3], and 1,240 free publications were found on PubMed [4] sites that are directly related to the circadian rhythm and light at night topics. Among those publications, recently published research papers (2010-2020) have been selected for review to narrow down the reviewed light sources to light emitting diodes (LEDs) as it is noted that the circadian system is susceptible to the blue wavelengths and LEDs are showing a peak in their spectrum at the same sensitivity area. At the end of the review, possible direct connections between the use of artificial light and adverse physiological and psychological effects with more severe health problems have been found. In addition, the current light pollution studies showed that vast majority of the global population is living under light polluted skies and possibly experiencing the negative effects of disrupted circadian system daily and therefore experiencing deteriorating effects of circadian disruptions and personal wellbeing. As the use of artificial light rapidly increases with global population, exposure to artificial light will increase exponentially in the near future and not only human beings but also the rest of the ecosystem will suffer from its negative effects. Because of this rapid change we should start implementing more stringent guidelines written with consideration for the health implications of artificial light while controlling the excessive use of it. Also, as the LED based lighting systems increase their popularity worldwide, we should start researching a possible modification to reduce the impact of the LED lighting on circadian system and its negative effects on human wellbeing.
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Guan, Enhui, Xinyi Cheng, Xiao Zhang, et al. "17‐3: A Novel Pixel‐level Local Dimming Backlight System for HDR Display Based on mini‐LED." SID Symposium Digest of Technical Papers 51, no. 1 (2020): 231–34. http://dx.doi.org/10.1002/sdtp.13846.
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Padiyar U., Suprabha, Vedavyasa Kamath, and Shruthi Ramachandra. "Close Loop Control of Daylight - Artificial Light Integrated System." International Journal of Engineering & Technology 7, no. 4.41 (2018): 75–78. http://dx.doi.org/10.14419/ijet.v7i4.41.24304.
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The paper proposes a system to achieve optimal lighting level in a given workspace where the user can define the amount of lux level required on the workplane. A hardware-software interface model is developed with close loop control mechanism to maintain the user-defined lux level, this is achieved by continuous monitoring of the light level and dynamic control of window blinds and dimming of artificial light system. Since illuminance level in the space is influenced by daylight and artificial light, a lighting fixture with CFL connected to 1-10V dimmable HF electronic ballast and window blinds controlled by servo motor are incorporated in the workspace. Based on the feedback obtained by the LDR sensor module placed on the floor of the workspace, PID control algorithm programmed in LabVIEW actuates the servo motor and the ballast. NI-LabVIEW along with NI-USB6008DAQ card is used to monitor and control lighting. Â
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Erkan, Anil, David Hoffmann, Timo Singer, et al. "Influence of Headlight Level on Object Detection in Urban Traffic at Night." Applied Sciences 13, no. 4 (2023): 2668. http://dx.doi.org/10.3390/app13042668.
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The purpose of this work is to determine the influence of the low beam intensity of motor vehicle headlights on detection conditions in urban traffic. For this purpose, studies with fourteen subjects are conducted on three differently illuminated test roads, in which the low beam intensity is dimmed from off to fully on. At each dimming level, the subjects indicate whether or not they have detected the object, which is realized by a flat target and occurs at sixteen different positions in front of the vehicle. In addition, considerations of the contrast curve and the visibility level are made in order to determine the influence of switched off and fully switched on headlights. The results show that the negative contrast created by the existing street lighting creates detection conditions at least as good as full low beam intensity in almost all cases. The results further indicate that the influence of the low beam intensity increases with decreasing distance to the object and decreasing illumination levels. The results of this work show that an increase in low beam intensity initially leads to poorer detection conditions; thus, the option of reducing low beam intensity should be considered in urban traffic space.
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Cui, Meng, and Yu Lin Qi. "Research and Design of Urban LED Street Lamp Wireless Management System." Applied Mechanics and Materials 602-605 (August 2014): 2893–96. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.2893.
Full textAbstract:
This article will Wave Mesh wireless ad-hoc network technology is applied to urban LED street lamp management system,with the single chip microcomputer 80C51F310 as the core,using real-time sensor testing environment brightness, and according to the brightness level of brightness, the LED street light illumination automatic adjustment;Aiming at the condition of the midnight staff less activity,using pyroelectric infrared human detection to control the brightness of the street lamp, the experimental data proved that energy saving effect is remarkable.The system safe and reliable, low cost,It has the advantages of single lamp remote monitoring,automatic dimming,electric energy measurement,alarm,fault diagnosis and fault location,etc.