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Lighting Quality and Well-Being
Published in Agnieszka Wolska, Dariusz Sawicki, Małgorzata Tafil-Klawe, Visual and Non-Visual Effects of Light, 2020
Agnieszka Wolska, Dariusz Sawicki, Małgorzata Tafil-Klawe
Both standards (EN 12464-1 European standard [2011] and WELL Building Standard [WELL 2019a]) treat the problems of flicker and the stroboscopic effect briefly. However, the considerations come down to recommendations for limiting flicker. The properties and parameters describing the phenomenon are not analyzed. This is because flicker is most often associated with efficiency and work performance, and above all with its hazardous effects and safety at work [van Bommel 2019]. The assessment of flicker (and the stroboscopic effect) is difficult. The basic parameter associated with flicker is the frequency of changes (flicker frequency – ff). However, analyzing the phenomenon requires additional parameters and is quite complicated. It also depends on the features typically associated with visual performance. The problems of flicker perception and the stroboscopic effect are discussed in the context of visual performance in Section 5.7. The parameters needed to measure and assess the phenomena are examined in Section 10.2.
IEEE 802.15.7: Visible Light Communication Standard
Published in Zabih Ghassemlooy, Luis Nero Alves, Stanislav Zvánovec, Mohammad-Ali Khalighi, Visible Light Communications, 2017
Murat Uysal, Çağatay Edemen, Tunçer Baykaş, Elham Sarbazi, Parvaneh Shams, H. Fatih Ugurdag, Hasari Celebi
The two main challenges for communication using visible light spectrum are flicker mitigation and dimming support. Flicker refers to the fluctuation of the brightness of light. Any potential flicker resulting from modulating the light sources for communication must be mitigated because flicker can cause noticeable, negative/harmful physiological changes in humans. To avoid flicker, the changes in brightness must fall within the maximum flickering time period (MFTP). The MFTP is defined as the maximum time period over which the light intensity can change without the human eye perceiving it. While there is no widely accepted optimal flicker frequency number, a frequency greater than 200 Hz (MFTP < 5 ms) is generally considered safe. Therefore, the modulation process in VLC must not introduce any noticeable flicker either during the data frame or between data frames.
Voltage Issues in Power Networks with Renewable Power Generation
Published in Neeraj Gupta, Anuradha Tomar, B Rajanarayan Prusty, Pankaj Gupta, Renewable Energy Integration to the Grid, 2022
Sushil Kumar Gupta, Kapil Gandhi
Flicker may limit the peak power generation through wind turbine which is integrated to the main grid. The main cause of flicker is voltage fluctuations, which are induced due to sudden change in the load power. Wind turbine characteristics and grid conditions also affect the flicker emission of grid-connected wind turbines. Flicker will generate more disturbance in fixed speed wind turbine while less disturbance in variable speed wind turbines. The power output of the wind turbine will reduce as the rotor blade passes near the tower. It will cause periodic variations in a frequency of approximately 1 Hz.
Effects of Temporal Light Modulation on Cognitive Performance,Eye Movements, and Brain Function
Published in LEUKOS, 2023
Jennifer A. Veitch, Patricia Van Roon, Amedeo D’Angiulli, Arnold Wilkins, Brad Lehman, Greg J. Burns, E. Erhan Dikel
TLM can affect visual perception, cognitive performance, and health (CIE 2017; IEEE Power Electronics Society 2015). Visual perception effects of TLM are called temporal light artifacts; these occur in at least three forms: flicker, the stroboscopic effect, and the phantom array effect. Flicker is “perception of visual unsteadiness induced by a light stimulus the luminance or spectral distribution of which fluctuates with time, for a static observer in a static environment” (CIE 2020), and occurs for light sources with TLM at frequencies lower than approximately 60–80 Hz. The Talbot-Plateau law suggests that the visual system will merge the flickering signals, which will then appear continuous when the frequency is greater than a critical value, known as the critical fusion frequency (CFF). When the eye is adapted to typical interior light levels (photopic adaptation), the CFF varies with viewing conditions between observers but is around 60 Hz for most people (Boyce 2003). Under everyday viewing conditions with photopic adaptation, TLM at frequencies higher than an individual’s CFF is not generally reported as visible (i.e., there is no flicker), although transient visual effects have been reported up to 200 Hz (Nakajima and Sakaguchi 2015) when there is a large enough change in the weighted moving average stimulus luminance, and there is electroretinogram evidence that the visual system responds to TLM at rates up to ~200 Hz (Berman et al. 1991).
Assessment of the effect on the human body of the flicker of OLED displays of smartphones
Published in Journal of Information Display, 2021
In Equation (1), and are the maximum and minimum values of the luminance measured from the light source. Note that (1) is not related to the change in frequency. The IEEE Standards PAR1789 group uses the results of several independent experiments to describe, as follows, the relationship between the frequency of the flicker and the percent flicker that affects the human body. First, the no-observable-effect limit is set by combining the data from [9] and [10]. Then the low-risk region is derived by comparing it with the data from [10,11] and the results of a case study by the U.S. Department of Energy/Pacific Northwest National Laboratory (DOE/PNNL) [12]. The criterion recommends that the percent flicker be 5% or below at 90 Hz or less, because this is the luminance range at which flicker can be detected, which can cause serious symptoms such as seizures. The 5% criterion alone does not cause intense symptoms and may still cause discomfort. The standards for the flicker frequency, , have been established for invisible flicker at frequencies higher than a visible flicker. Low-risk level: percent flicker No-observable-effect level: percent flicker
Integrated DWT-DHT Feature Set for ABC Optimized SVM-Based PQ Classifier
Published in Electric Power Components and Systems, 2023
Flicker is generated by creating severe voltage fluctuations by introducing fluctuating loads. The fluctuating load is introduced by varying load resistance using an Arduino-based control circuit. The circuit diagram for creating the flicker disturbance and the corresponding waveform obtained are shown in Figure 7. The noise present in the disturbance signals captured using practical hardware circuits is found to be around 28 db.