Flicker Characteristics Research Articles

Flicker Noise Behavior in Resistive Memory Devices With Double-Layered Transition Metal Oxide

Characteristics of flicker (or <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{1}/f$</tex></formula> ) noise have been investigated in resistive-switching random access memory (RRAM) devices with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX"> $\hbox{TiN/Ti/TiO}_{x}/\hbox{HfO}_{x}/\hbox{TiN}$</tex></formula> double-layered (DL) metal oxide structure. In DL-RRAMs, no significant difference is found in the normalized current noise power spectral densities of the high- and low-resistance states, unlike RRAMs with the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{TiN/Ti/TiO}_{x}/ \hbox{TiN}$</tex></formula> SL structure. Based on comparative analysis, we demonstrate that the dominant <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{1}/f$</tex></formula> noise source of DL-RRAM is located near the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{TiO}_{x}/\hbox{HfO}_{x}$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\hbox{HfO}_{x}/\hbox{TiN}$</tex></formula> interfaces, and the origin of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \hbox{1}/f$</tex></formula> noise is modeled to be the mobility fluctuation. A unique measurement method, which completely breaks down the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{HfO}_{x}$</tex></formula> layer only, was employed for a systematic analysis of RRAMs with three different structures.

Effective Voltage Flicker Calculation Based on Multiresolution S-Transform

This paper introduces a new method for calculating the voltage flicker characteristics. A voltage waveform envelope, which captures the main flicker characteristics, is obtained by calculating rms values instantaneously using a moving window approach. The S-transform (ST) is then used to extract the voltage flicker components for each frequency. The multiresolution characteristic of the ST provides timing data which presents a “Magnitude-Time” and “Frequency-Time” contour for tracking flicker. The effects of signal sampling rate, voltage harmonics, and frequency variation on the calculation results are considered. The results show that the proposed method can identify the frequency and magnitude of flicker components in a short time and with very good precision. This method is independent of calculating the fundamental frequency of the system, which has been used for flicker index calculation. Finally, the method is tested on a real voltage flicker signal sampled from the voltage signal of an electric arc furnace. The results are quite promising.

Effects of flicker characteristics from solid-state lighting on detection, acceptability and comfort

A study to assess the detection and acceptability of flicker and stroboscopic effects under different lighting conditions was conducted. Frequencies from 50 Hz to 300 Hz were assessed, as well as different modulation amounts, duty cycles, waveform shapes and correlated colour temperatures. For the range of conditions evaluated, direct perception of flicker was negligible at 100 Hz or higher, but stroboscopic effects could be perceived at 300 Hz. Reducing flicker modulation from 100% to 33% decreased perception of stroboscopic effects. A higher duty cycle was associated with slightly lower discomfort. The implications for solid-state lighting systems producing high-modulation flicker are discussed.

Investigation of Retinal Spatial Interaction Using mfERG Stimulation

Introduction:Adaptation is one of the key characteristic of our vision which can maximize the visual function. It applies to both spatial and temporal characteristics. The fast flickering stimulation characteristics of the multifocal electroretinogram (mfERG) can be applied to analyze retinal interactions between flashes and to investigate retinal temporal processing mechanism. Besides, its localized stimulus pattern can also be used as a tool for investigation of retinal spatial interaction.Methods:The mfERG recordings were obtained from 13 eyes of 9, normal, six-week-old Yorkshire pigs. The control mfERG was measured using the pattern consisting of 103 nonscaled hexagons, where each hexagon will follow a pre-set m-sequence. Nine isolated hexagons from the 103 nonscaled pattern were chosen in the masking mfERG stimulation, where the remaining hexagons were kept at constant luminance. First-order and the second-order kernel responses were analyzed, which represent the outer and inner retinal responses, respectively.Results:The second-order kernel response amplitude from the visual streak region showed a significant enhancement under the masking stimulation.Conclusions:The enhancement found under the masking condition indicates that the retinal signal will be suppressed under surrounding flicker stimulation, and this spatial inhibitory mechanism may originate from the inner retina.

Voltage Fluctuation and Flicker Monitoring System Using LabVIEW and Wavelet Transform

The paper puts forward a method which uses wavelet multi-resolution analysis to extract characteristics of voltage flicker, establishes the arithmetic model of voltage fluctuation and flicker, and it can detect the amplitude modulation waveform of the voltage flicker, and examine abrupt-change time, frequency, and amplitude of the amplitude modulation waveform. A voltage fluctuation and flicker monitoring system based on virtual instrument was developed, where the wavelet transform was applied to virtual instrument by using the MATLAB script node in LabVIEW. The evaluation indices of short-term flicker severity were obtained by using statistic sorting algorithms. Sensation level weighted filter, Square multiplier and first order low pass filter were designed.

Low-Frequency Oscillation of a Non-Premixed Flame on a Bluff-Body Burner

The flickering characteristics of a non-premixed flame interacting with von Kármán vortex street on a bluff-body burner were investigated experimentally with varied velocities of the central fuel jet and annular air stream. Flow visualization in terms of a shadowgraph, planar laser-induced fluorescence of hydroxyl, and Mie scattering, which was obtained via PIV used to analyze the flow field, indicated that the flame flickering was caused by periodically growing, toroidal vortices outside the flame surface that were much larger than those observed in buoyant jet flames. In contrast to a weak dependence of the latter on the co-flowing air velocity and the central fuel velocity, the present case was strongly correlated with the von Kármán vortex street shed from the rim of the air stream that produced vortex pairing downstream, and was coupled with buoyancy effects rendered by the pilot flame in the recirculation zone as well as the central jet flame. The flame surface was consequently wrinkled substantially by the strong flame-vortex interaction, leading to frequent local extinction. Furthermore, due to a significant extension of the residence period, the frequency of oscillation was greatly decreased when the velocity of air flow was large enough to introduce a recirculating flame behind the bluff body. It was then increased when the air velocity increased. In contrast, a maximal frequency of oscillation was generated when the fuel velocity was increased, which occurred as the flame mode altered from a recirculation zone flame to a jet-dominated flame, for which the central jet flame was about to penetrate the recirculation zone. This frequency was caused by the intense interactions among the recirculated air, the central jet flame, and small eddies convened around the dome of the recirculation zone. The global behaviors of flame flickers could be further summarized using the Strouhal number and the Reynolds number of fuel jet in a relation of (St)(Re c ) = C, whereas the constant C was modified by the Reynolds number of air flow.

Study on dynamical behavior of turbulent premixed V-flames

Differential interference contrast method was applied to investigate the flickering characteristics of V-flame in terms of both temporal and spatial scales. The flow characteristics of incident premixed combustibles were measured by means of laser Doppler anemometry (LDA). The characteristics of wake flow behind the stabilizing rod were obtained with numerical simulation. While the integral temporal scale of incident turbulence is about 1ms, the integral spatial scale about 2 mm, the characteristic flickering time scale is about 83 ms and spatial scale about 10 mm. The flame flickering frequency is more than 12 Hz, does not comply with the wake vortex shedding frequency, which is about 110 Hz. It is well-known that the flickering of V-flame is affected by both the incident turbulence and the wake flow after the stabilizing rod, but the result of the paper shows that the relationship between flickering characteristics and flow characteristics is much more complicated by the chemical reaction.

Characterizing the Flashing Television Images that Precipitate Seizures

Television is by nature a flickering medium. It is also designed to convey images that flash or flicker. This paper seeks to characterize the stimulus parameters of broadcast materials that have been responsible for triggering epileptic seizures. Three sources of evidence are considered: the characteristics of flicker and pattern predicted to induce seizures on the basis of clinical studies; the statistics of broadcast images; and the characteristics of video sequences that have been associated with anecdotal reports of seizures. The results of these studies have contributed to a revision, in mid-2001, of a Guidance Note issued by the Independent Television Commission (ITC) in the U.K. seeking to protect, so far as is reasonably practicable, the section of the population that is liable to photosensitive epilepsy.

Flicker characteristic estimation of an AC electric arc furnace

Abstract This paper describes the estimation of the stochastic flicker characteristics for an electric arc furnace (EAF) over a complete heat. These characteristics include stationarity, normality and correlation. Besides, the basic statistical probability were assessed by varying sampling period, too. The estimation and the assessment were implemented by a microcomputer-based instrumentation system. The test results for a typical AC arc furnace show that: (1) most flicker characteristics are stationary or weakly stationary during different periods of a heat cycle, but most of their probability density functions are not normally distributed; (2) the voltage and current fluctuations in the same phase are highly correlated; (3) the flicker converges at a value with a ±5% deviations from the value based on a basic sampling period, if the sampling period is decreased below 12 s.

On-line flicker measurement of gaseous flames by image processing and spectral analysis

The flicker of a flame is an important physical parameter associated with the characteristics of a combustion process. This paper presents a novel instrumentation system developed for on-line continuous flicker measurements of combustion flames. The system comprises a high-speed CCD camera, a frame grabber and associated image processing software. The flicker signal was obtained by processing the radiation intensity of individual pixels within the luminous region of a flame image. Power spectral density analysis was performed to obtain the frequency components of the flicker signal. The quantitative flicker of a flame is defined in terms of weighted spectral components in the frequency domain and this definition has been proven to be well suited to quantification of the flickering characteristics of a flame. A tungsten lamp driven by a frequency-varying power supply was employed to calibrate the measurement system. The calibration results show that the system is capable of measung the flicker of an unknown light source with a relative error no greater than 3% . The system developed has been utilized to investigate the relationship between the flicker of a diffusion flame and the burner diameter, and to study the effect of the equivalence ratio on the flicker of a premixed flame under a range of combustion conditions. The experimental results obtained by both motion image analysis and spectral analysis have demonstrated that the flicker of a diffusion flame depends predominantly on the burner diameter. It has also been found that the flicker of a premixed flame varies with the equivalence ratio and a peak flicker exists for a given air flow rate.

人間の視覚・聴覚情報 臨界融合周波数以上で点滅する視野内を運動する光刺激によるフリッカ知覚

The frame frequency used in TV and movies, as well as that used in VDT's, is higher than the critical fusion frequency (CFF). But, because the CFF is determined for a static scene, flicker is perceived when there is a moving object in the dynamic scene. In this research we investigated the fundamental characteristics of flicker perceived in the dynamic scene. The stimulus was a moving edge in the flickering visual field by Maxwlian view, and the flicker frequency exceeded the CFF. The threshold frequency of flicker perception at the moving edge, which rose with the edge velocity from about 6 deg/s, then saturated at about 90 Hz when the edge velocity was about 20 deg/s and then rose again. The result suggests that the mechanisms of flicker perception depends on the velocity of the moving stimulus.

A method of evaluating flicker and flicker-reduction strategies in power systems

The UIE/IEC flicker characteristics of a three-phase power system which includes resistance welders are evaluated in this paper. Welder operation produces cyclic flicker which leads to customer complaints. An adaptive VAr compensator (AVC) has been installed to reduce flicker. In order to investigate the effectiveness of the AVC and to set the stage for the analysis of alternative control strategies, a detailed computer model of the given power system, including the AVC, has been developed. The model also includes a simulation of the UIE/IEC flickermeter to determine the effectiveness of the AVC in an objective manner. The simulated system response is compared with actual system measurements revealing excellent agreement. The modeling methodology set forth provides an efficient and convenient means of evaluating complex flicker resulting in a simple measure of human irritability.

Vibrational Analysis of the Structure of Crystalline Gramicidin A

increased Gss from 20to 50-fold. In cases where a large Gss was already present in symmetric pH solutions, the rate of approach to Gss increased fivefold. In two experiments, returning the trans pH to 4.7 reduced the rate of approach to Gss but not its ultimate value. Single-channel burst duration and flicker characteristics within a burst were unchanged, suggesting that by the scheme presented above the only rate affected would be the unmeasured k2 (see Fig. 1).

Effects of Patterning on Flicker Frequency

Flicker was studied as perceived on a raster-scan CRT-based computer terminal in a typical use environment. The subject of the research was the relationship between the perception of flicker and the kind of spatial image presented. Both traditional images (filled white disks or squares) and images consisting of text and line drawings, similar in content to typical graphic computer terminal displays, were used in the study. This study measured the flicker perception of eight people. The most significant finding from this study was that CFF thresholds for some images presented on CRT displays in a typical use setting, differed significantly from more traditional images used in most CFF studies reported in the literature. For the eight images tested, the two which exhibited significantly higher CFF thresholds were lines or text on a black background (patterns 3 and 4). Therefore, an important factor to be considered in the prediction of the flicker characteristics of a 60 Hertz, noninterlaced CRT display in conditions similar to those of this study is the choice of normal video (black background) or reverse video format. The white background video format is likely to flicker when the display luminance is above 20 ft-L while the black background video format threshold was about 80 ft-L for both patterns 3 and 4. Alternatively, this luminance difference corresponds to about a 10 Hertz shift in CFF. In this study, the choice of video format alone, resulted in a luminance difference of 60 ft-L at CFF, or alternatively, resulted in a 10 Hertz shift in CFF at a particular luminance, for images normally found on actual CRT displays.

A spectral compensation method for determining the flicker characteristics of the human colour mechanisms

The modulation depth of a light of intensity I 1 , at wavelength λ 1, and that of a light of intensity I 2 at wavelength λ 2 can be so chosen that a patch of light containing these two modulated monochromatic beams is “seen” as a steady field by one class of cones. This condition is reached if for one class of cones the increase in effective quantum catch due to an increase in I 1 , is compensated by an identical decrease in I 2 , and vice versa. Implicitly this stimulus is perceived as a modulated beam by another class of cones. The silencing of either of the two classes of cones in the red-green spectral range by this spectral compensation method resulted in similar flicker fusion curves for both the “red” and “green” cones, granted identity in respective states of adaptation. Our results show that the isolated human medium and long wavelength cone systems do not exhibit low frequency attenuation even at retinal illuminations as high as 1250 td.

Sinusoidal flicker characteristics of the color-sensitive mechanisms of the eye

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A Study of Television Image Characteristics: Part Two: Determination of Frame Frequency for Television in Terms of Flicker Characteristics

During 1931 and 1932 an investigation was carried out to obtain quantitative information on the several characteristics of television images. Part One of this paper covered those characteristics relating to image detail. This paper, Part Two, covers a determination of frame frequency in terms of flicker characteristics. The analysis is based on a number of simple tests largely in terms of equivalents so that a wide range of conditions might be studied. Conclusions are reached regarding several means for minimizing flicker.