Flicker Values Research Articles

Blue-Violet Light-Blocking Eye Protectors in Dental Practice: A Preliminary Study

Healthcare professionals are exposed to various intense light sources during dental practice. Of particular concern is blueviolet light (wavelength 380-500 nm), which can impact retinal health, necessitating effective mitigation strategies. In this study, we assessed the practical utility of lenses designed to reduce blue-violet light to wavelengths of approximately 420 nm or shorter within the dental practice setting. Two dentists and four dental hygienists participated in the study. The participants wore either blue-light-reducing lenses or lenses with no effect for one month. The degree of eye strain was evaluated using flicker values. The results revealed that four of the six participants experienced reduced eye strain while wearing blue-violet light-reducing lenses. In conclusion, this study addresses the acknowledged impact of blue-violet light on retinal health. However, the long-term prognosis remains uncertain. Therefore, considering the potential unknown effects, it is necessary to discuss the use of blue-violet light-cut lenses in everyday practice as a risk-management strategy.

36.3: A Low Flicker Micro‐LED Pixel Circuit Based on Amorphous InGaZnO Thin‐Film Transistors

We proposed a novel 6T1C pixel circuit as well as its driving scheme based on amorphous InGaZnO thin‐film transistors (a‐IGZO TFTs) for micro‐LED displays. Compared with the conventional 7T1C pixel circuit, the new design not only simplified the circuit structure but also exhibited apparently better threshold voltage compensation effect as well as much lower flicker value.

5.3: Brightness Decline Mechanism at Low Frequency Display on LTPS LCD

5.3: Brightness Decline Mechanism at Low Frequency Display on LTPS LCD

Flicker emission of electric vehicle charging in low voltage grids

With an ever-changing electrical grid structure and new loads like electric vehicles and heat pumps, a continuous look at power quality standards is necessary to ensure a functional and sufficient energy distribution. In this paper the impact of electric vehicles, heat pumps and photovoltaic systems on the flicker values in low voltage grids is investigated for different grid types. The results of these investigations show that especially suburban grids, but also rural grids with very high line impedances, experience increased flicker values in specific scenarios. However, the limits of flicker values, which are set in the EN 50160 are not exceeded in any of the scenarios that are investigated.

Voltage Fluctuations and Flicker in Prosumer PV Installation

In this paper, we present problems connected with voltage fluctuations in low-voltage networks caused by small PV sources installed in an LV network. For the purpose of analysis, high-resolution data gathered at the output of real PV sources for 4 months in 2 locations are used. Data are processed to analyze the impact of different network parameters on voltage fluctuations and voltage flicker. The resulting values of flicker and fluctuations are given so the assessment of the impact of PV sources can be made before the connection of new sources to the power grid. Moreover, the methodology of analysis is presented in detail so the impact of similar PV sources on voltage could be analyzed. Finally, general conclusions connected with measurement, analysis, and mitigation are given.

Identification of the flicker source in the power supply systems

THE PURPOSE. To consider issues related to the study of methods for determining the sources of violations of the quality of electrical energy in power supply systems, in particular consumers which create rapid voltage changes or voltage fluctuations that create rapid changes in the luminous flux in electric lighting installations. Show that electrical receivers with a sharply variable operating mode are sources of fluctuations in the consumed current and voltage in the electrical network of power supply systems, which in turn manifests itself in the form of unacceptable values of one of the indicators of the quality of electricity - flicker, defined as the subjective perception of fluctuations in the luminous flux of lighting devices. To study the possibilities of determining the places of occurrence of significant voltage fluctuations without the use of expensive and complex instruments for measuring flicker values in the electrical network. To develop a simplified method for determining the locations of electricity consumers that negatively affect the operation of electric lighting systems and, ultimately, the vision of personnel. Conduct a check on a computer model of a simplified method for determining the places of occurrence of voltage fluctuations that are inadmissible in their magnitude, which are expressed in the appearance of significant doses of flicker that exceed the standard values.METHODS. Solving the problem, a computer model was used, created in the Simulink extension package of the Matlab scientific and technical calculation system.RESULTS. The article describes the relevance of the problem, discusses the quality of electricity in power supply systems. It has been shown using experimental data that in electrical networks there is an excess of the standard values of flicker doses. The possibility of using interharmonic components of the mains voltage to determine the sources of unacceptable doses of flicker is considered. A simplified method for finding flicker sources based on obtaining the values of the derivatives of currents at various points of the electrical network is presented. Computer simulation of an electrical network diagram with electrical receivers, which have both calm and sharply variable nature of work, has been performed. It is shown that the use of the values of the derivatives of the current at various points of the electrical network makes it possible to identify the sources of the occurrence of unacceptable doses of flicker.CONCLUSION. The occurrence of significant rapid voltage changes in the electrical network negatively affects vision, which is inevitably accompanied by increased personnel fatigue and can lead to industrial injuries. The results obtained by the authors of the article show that it is possible to use it to determine the places of occurrence of large voltage fluctuations, which are manifested in unacceptable doses of flicker of the derivatives of currents. It should be taken into account when conducting surveys of power supply systems in order to use fairly simple hardware to identify sources of disturbance in the quality of electrical energy.

P‐3.3: Analysis and Improvement of Flicker NG on VR Display

With the continuous development of liquid crystal display, VR products are increasingly favored by the market. the main form of VR products is wearable, the pursuit of thin and light, high‐definition and other qualities. Therefore, VR screens need to have high PPI, fast response, high refresh rate and other technical effects. To achieve the above effects to the VR screen R & D introduced many technical bottlenecks, this article explores the VR product display problem flicker NG.The paper proposes two innovative solutions to improve the flicker NG of VR products: 1) asymmetric pixel shading layer design, targeted to suppress the generation of TFT source/drain photogenerated carriers and improve the increase of pixel TFT leakage current by high bright backlight without reducing the aperture rate. 2) Adding transparent electrodes with common electrode co‐potential, in parallel with pixel storage capacitor Cst, which forms storage capacitance compensation Cst0 (Cst0⩾Cst) and enhanced pixel TFT voltage holding capacity after improved pixel storage capacitance Cst+Cst0.The theoretical investigation and practical verification show that the above scheme is effective in reducing the flicker value of VR products.

Voltage Flicker Detection Based on Probability Resampling

Digital flicker detection devices need to store a large amount of evaluation data during measurement process, which leads to high requirements for hardware resources and algorithm execution efficiency. In this paper, a digital flicker detection method based on probability resampling is studied. In particular, before statistical evaluation, probability resampling is applied to screen the instantaneous flicker visual sensitivity data to compress redundant data. Additionally, the effectiveness of the method was numerically simulated and experimentally tested. The results show that the proposed method can accurately measure the voltage flicker value and can effectively compress the redundant evaluation data to be evaluated and has significant advantages in releasing hardware storage space, in improving algorithm execution efficiency and real-time performance, and in reducing processor workload. This method provides an engineering application reference for designing digital flicker detectors, especially for the software upgrade of traditional power quality testing equipment.

Simplified and fast method without considering filter for voltage flicker detection

Voltage fluctuations caused output variation in the distributed energy system (such as solar, photovoltaic, and wind) produce flickers. The extraction of voltage flicker envelope parameters and accurate calculation of voltage flicker values are important for voltage flicker detection. Traditional digital filters need to be calculated according to the sampling frequency before they can be designed so that the flicker meter can only sample at a fixed frequency. To overcome the shortcomings of digital filters, a new method for measuring flickers is presented in this study. The proposed method uses analytical mode decomposition (AMD) based on spectral correction and a novel constructed mutual convolution window. The voltage flicker envelope can be extracted using an AMD method, which can replace the filter used in traditional methods, it can be analysed to obtain the corrected spectrum, which is based on an improved fast Fourier transform. The proposed method simplifies the voltage flicker detection process and exhibits high detection accuracy, which with lower detection relative error and stronger anti-interference ability. The simulation analysis and experimental results show that this approach can effectively overcome problems associated with voltage flicker measurements, such as single modulation wave frequency change and multi-frequency modulation wave fluctuation.

Total output power variation of several small wind turbines

There is a concern that connection of several small wind turbines may cause severe voltage fluctuation and voltage flicker in low-voltage distribution lines due to their output power variations. In this study, output power variations of four 5-kW-class small wind turbine systems were measured with an interval of 0.1 s at a site in Wakkanai, Hokkaido, and their correlations and smoothing effect in the frequency range from [Formula: see text] to 5 Hz were analyzed and compared with those of five residential photovoltaic power systems. The results indicate that a smoothing effect occurs more in small wind turbines than in photovoltaic systems, because of lower correlation coefficients in lower frequency ([Formula: see text] Hz) components. Voltage flicker at the point of common coupling was also measured and it was confirmed that the impact of small wind turbines on voltage flicker is low enough at the site. In addition, the upper limits of the installation number and/or the system resistance are estimated theoretically using the measured flicker values.

Assessment of fatigue caused by VDT operation

In recent years, there has been a growing interest in smart glasses (SG) incorporating augmented reality (AR) technology. The most remarkable feature of SG is that users can execute tasks with both hands while getting necessary information while without taking their eyes off the task at hand. Such hands-free (HF) access to information can help prevent contamination. We are engaged in developing HF manuals for medical applications using SG. Use of SG could be expected to be associated with eye strain and headaches, but these could also occur when the users read manuals displayed on a LCD display (PC) or manuals printed on paper (Paper). In order to compare the effects of presentation of manuals in different modalities, 77 randomly selected students and faculty members were assigned to read HF (n=27), PC (n=40), and Paper (n=10) manual. The degree of eye strain induced by each presentation was compared by the flicker value, blinking frequency, high frequency component (HFC), pulse rate and “subjective symptoms”1), before and after loading for an hour. The results revealed less fatigue in the group assigned to HF as compared to the other groups. Therefore, there are no major obstacles to HF manual development.

Design and development of harmonics and flicker generator (HFG) for electromagnetic compatibility (EMC) application

It is observed that the standards IEC 61000-3-2 and IEC 61000-3-3 do not discuss the calibration methods required to evaluate the performance of a Harmonics and Flicker emission test setup, used for Electromagnetic Compatibility (EMC) measurements. When the instrument does not have a direct standard procedure, reference data for comparison analysis is required to calibrate/verify any equipment or system. In particular, emission measurement systems in EMC laboratories necessarily require a reference source value to check the performance of the test system periodically. This necessitates the design and development of a Harmonics and Flicker Generator to not only identify a known repeatable Harmonics and Flicker value but also to find out the deviation of the test setup. The proposed Harmonics and Flicker Generator is intended to be used for the calibration of Harmonics and Flicker emission test setup and for Inter Laboratory Comparison analysis (ILC) to evaluate the performance capabilities of the EMC test laboratories. This paper discusses the Harmonics and Flicker generator design techniques, schematic circuit, functional description, performance analysis and results.

Predicting Granulation “Flicker” and Radial Velocity “Jitter” from Spectroscopic Observables

Abstract Surface granulation can be predicted with the mass, metallicity, and frequency of maximum oscillation power of a star. Using the orders-of-magnitude larger Apache Point Observatory Galaxy Evolution Experiment-Kepler (APOGEE-Kepler) sample, we recalibrate the relationship fit by Corsaro et al. for “flicker,” an easier-to-compute diagnostic of this granulation. We find that the relationship between the stellar parameters and flicker is significantly different for dwarf and subgiant stars than it is for red giants. We also confirm a dependence of flicker amplitude on metallicity as seen originally by Corsaro et al., although the dependence found here is somewhat weaker. Using the same APOGEE-Kepler sample, we demonstrate that spectroscopic measurements alone provide sufficient information to estimate the flicker amplitude to 7% for giants, and 20% for dwarfs and subgiants. We provide a relationship that depends on effective temperature, surface gravity, and metallicity, and calculate predicted flicker values for 129,000 stars with APOGEE spectra. Finally, we use published relationships between flicker and radial velocity jitter to estimate minimum jitter values for these same 129,000 stars, and we identify stars whose total jitter is likely to be even larger than the granulation-driven jitter by virtue of large-amplitude photometric variability.

Research into the Effect of Photometric Flicker Event on the Perception of Office Workers

Today the number of office workers has reached to an enormous number due to the fast-growing technology. Most of these office workers spend long hours in enclosed spaces with little/no daylight penetration. The lack of daylight causes physiological and psychological problems with the workers. At this point lighting systems become prominent as the source and the solution of the problem. Photometric flicker event which arises in the lighting systems can sometimes become visible and brings a lot of issues with it. In this paper, an experimental work has been done to investigate the effect of flicker. For this purpose, the flicker values of 3 different experiment rooms for different lighting conditions and scenarios have been measured and a questionnaire study has been carried out in the experiment rooms with 30 participants. In conclusion, the effect of the flicker event on the volunteers have been classified and some methods have been proposed not to experience flicker effects.

New flickermeter sensitive to high‐frequency interharmonics and robust to fundamental frequency deviations of the power system

In this study, a new flickermeter sensitive to high-frequency interharmonics and robust to fundamental frequency variations is proposed, implemented and tested. The standard IEC flickermeter, proposed in the 61000-4-15 IEC Standard, considers only the interharmonics around the fundamental frequency and ignores the effect of high-frequency interharmonics on the voltage peak fluctuation. However, high-frequency interharmonics have been shown to have significant effect on the flicker in the literature. This work combines the effect of both low- and high-frequency interharmonics on flicker, based on a voltage-peak-detection flickermeter algorithm. Using a spectral correction procedure applied during the flicker computation, the proposed flickermeter becomes also robust to fundamental frequency variations existing in power systems. The accuracy of the proposed flickermeter has been tested and proved by synthetic voltage data including fundamental frequency variations, harmonics and interharmonics around the fundamental as well as those at higher frequencies. The results obtained with field data obtained from electricity transmission network changes as whether considering flicker effects of high-frequency interharmonics or not. In high-frequency mode, including the effect of high-frequency interharmonics, the proposed method yields higher flicker values compared to the IEC flickermeter. In low-frequency mode, excluding them, both IEC flickermeter and the proposed flickermeter yield close flicker.

Fundamental study on fatigue measurement in VDT work from speech analysis

AbstractWe aimed at developing a simple fatigue measurement system, so far the influence of the noise is small under laboratory environment and the experimenter side who uses a simulator. We have been studying fatigue measurement in a manageable environment. In order to show the effectiveness of our proposed method in a real environment, we collected fatigue measurement indexes before and after work for technical engineers of Software Development Company operating visual display terminals (VDT) work, changes before and after were compared and examined. As a result, in the conventional indexes, a significant difference was found in the pulse rate and the flicker value. We found that there are significant differences between before and after some speech of fundamental frequency, speech power, and period of speech indexes. In VDT work, there was a difference in flicker value as a fatigue measurement index, which was also supported by subjective symptoms and self‐evaluation results. In addition, since significant differences were also found in the speech index, in the work centering on the VDT work as well as the bicycle simulator so far, it was shown that speech indexes can be effective indicators.

Power Quality Performance Analysis of grid tied PV fed Parallel Pumping System under Normal and Vibrating Condition

The aim of this paper is to perform the relative study of power quality problems in a grid tied solar PV system, with and without vibration connected to a parallel pumping system at 1.0 bar set pressure by using two control techniques such as VVC+ & V/f. In case of vibrations, the effect of motor vibration problems on the dynamic performance and electrical power quality of water pumping system will be observed. Vibrations are introduced in the pumping system by loosening the base plate of the pumps. During motor vibrations, the instantaneous flicker values become high which leads to variation in the supply voltage and torque imbalance. The effect of power quality parameters in a solar feeder during normal conditions and vibrating conditions are analysed. In normal condition, the THD increases and the flicker is high only during transient period due to sudden voltage variations. A comparison has been made to observe the appropriate control method for pumping system with and without vibrations in a solar PV-grid connected system.

Study of Equilibrium Control System during a Lowering at Arousal Level

Contingent negative variation (CNV) is an event-related potential proportional to vigilance degree. A CNV graph shows an inverted U-shape, and this bioreaction disappears after falling below a threshold of vigilance degree. Previous studies have shown that the event-related potential gained with time decreases with sleep deprivation, and a decrease in the vigilance degree has been confirmed using Flicker values (FV) and the Stanford Sleepiness Scale (SSS) score. The minimum integrated value was recorded 24 h after the onset of sleep deprivation. In a present study, we used 36-h sleep deprivation. The FVs, SSS scores, and stabilograms were obtained every 90 min for 52 h, except for the 12 h of sleep. We herein examine whether the biocontrol system is changed by sleep deprivation. The time sequences in FV and SSS score showed that the degree of vigilance markedly decreased 22.5 h after the onset of this experiment, which supported CNV disappearance with sleep deprivation. The sway value with subjects' eyes closed was greatest 22.5 h after the onset of this experiment. Furthermore, there were no significant differences between the sway value during the above-mentioned sleep deprivation and that after 12 h of sleep. We considered that the equilibrium function and vigilance after 36-h sleep deprivation did not recover markedly well with sleep of sufficient duration. That is, the biocontrol process in the subconscious still proceeds after awakening. In this study, we focused on bioprocessing, especially the equilibrium function, during sleep deprivation and investigated the relationship between the equilibrium function and sleep deprivation. We obtained evidence supporting CNV disappearance after sleep deprivation for 36 h. The equilibrium control system without CNV was compared with that with CNV.

Retinal Vascular and Oxygen Temporal Dynamic Responses to Light Flicker in Humans.

PurposeTo mathematically model the temporal dynamic responses of retinal vessel diameter (D), oxygen saturation (SO2), and inner retinal oxygen extraction fraction (OEF) to light flicker and to describe their responses to its cessation in humans.MethodsIn 16 healthy subjects (age: 60 ± 12 years), retinal oximetry was performed before, during, and after light flicker stimulation. At each time point, five metrics were measured: retinal arterial and venous D (DA, DV) and SO2 (SO2A, SO2V), and OEF. Intra- and intersubject variability of metrics was assessed by coefficient of variation of measurements before flicker within and among subjects, respectively. Metrics during flicker were modeled by exponential functions to determine the flicker-induced steady state metric values and the time constants of changes. Metrics after the cessation of flicker were compared to those before flicker.ResultsIntra- and intersubject variability for all metrics were less than 6% and 16%, respectively. At the flicker-induced steady state, DA and DV increased by 5%, SO2V increased by 7%, and OEF decreased by 13%. The time constants of DA and DV (14, 15 seconds) were twofold smaller than those of SO2V and OEF (39, 34 seconds). Within 26 seconds after the cessation of flicker, all metrics were not significantly different from before flicker values (P ≥ 0.07).ConclusionsMathematical modeling revealed considerable differences in the time courses of changes among metrics during flicker, indicating flicker duration should be considered separately for each metric. Future application of this method may be useful to elucidate alterations in temporal dynamic responses to light flicker due to retinal diseases.

Research of flicker shift and stability on ADS mode LCD

ABSTRACTFlicker shift and flicker stability on advanced super dimension switch (ADS) mode liquid crystal display has been studied based on a 9-in. ADS mode screen which is oriented by rubbing. Firstly, the dependence of flicker shift on polyimide (PI) material was studied by testing four PI materials, including three PI materials of N company (N1, N2, N3) and one PI material of J company (J1). The results show that flicker value of N1 PI material changes most mildly with the continuous lighting time, that is, the N1 PI material performs best on flicker shift among the four PI materials. Secondly, the dependence of flicker stability on passivation layer (PVX) thickness, PI pre-cure temperature, PI main-cure temperature and post-anneal temperature were studied by conducting a four-factor and two-level 1/2 fractional factorial design of experiment (DOE) test. The results of the DOE test indicate that flicker stability could be improved by the increase of PI main cure temperature and the decrease of post-anneal temperature.