Multiwave-pumped mirrorless parametric oscillation in BaTiO3
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Oscillation (cell signaling)
Optically recorded Fresnel zone plates have proper spatial frequency characteristics for use as a laser scanner. Such grating scanners can easily be made and can scan over large cone angles with, however, severe aberrations of the diffracted laser beam at large deflection angles. Optically recorded Fresnel zone plates for laser beam scanning are investigated, and their aberration properties are analyzed. A method for removing the wavefront error caused by this type of zone plate is discussed, and the feasibility of the method is demonstrated.
Zone plate
Fresnel zone
Laser Scanning
Fresnel number
Diffraction efficiency
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Oscillation marks formation for slab continuous casting with high casting speed was expatiated through stress analyses of initial solidifying meniscus shell during an oscillation cycle with stabilizing casting status at 2.0m/min casting speed,and the optimizing direction of oscillation parameters along with increasing of casting speed was proposed through the analyses of relationship between oscillation parameters and maximum liquid friction force and maximum flux channel dynamic pressure combined with the influence of oscillation parameters on process parameters and practical equipment condition,finally,the oscillation parameters values as casting speed was 2.2m/min were determined.The results show that under the action of ferrostatic pressure,friction force and flux channel pressure the oscillation marks are formed along with solidification progress.The amplitude and non-sinusoidal factor should be increased,and oscillation frequency should be decreased with increasing casting speed in order to improve the oscillation effect and the oscillation marks shape. Rational oscillation parameters values are 145 min~(-1)(frequency),±5.0mm(amplitude)and 0.25 (non-sinusoidal factor),respectively,when casting speed was changed from 2.0 to 2.2m/min.
Oscillation (cell signaling)
Slab
Meniscus
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We have previously reported that the hydrogen evolution reaction (HER) in acidic water electrolysis shows a potential oscillation with amplitude of about 1 V. The oscillation, named HER oscillation, is accompanied with a periodic change in the evolution rate of hydrogen bubbles, i.e., hydrogen bubbles evolve more vigorously at low potentials than at high potentials, which has led us to propose a mechanism for HER oscillation (J. Electroanal. Chem., 713, 39 (2014)). In order to obtain a deeper insight into the mechanism of HER oscillation, this present work studies the effect of high pressure (e.g. 0.7 MPa) on the oscillation and current-potential curves. It reveals that any N-shaped negative differential resistance characteristics are not involved in HER oscillation unlike the majority of electrochemical oscillations. It also shows that a solution-stirring effect due to the hydrogen bubble evolution, which causes an enhancement of convection near the electrode surface, plays an essential role in HER oscillation. We thus conclude that the appearance of HER oscillation can be explained by considering that the enhancement occurs only at low potentials at which hydrogen bubbles evolve vigorously.
Oscillation (cell signaling)
Electrolysis of water
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In order to investigate the dominant mode in the oscillistor oscillation, the density oscillations of m=0 and helical modes have been studied by observing simultaneously both the transmitted microwave signal through a sample whose diameter was smaller than the skin depth and the potential difference between two probes alloyed axial-symmetrically on the sample. Experiments showed the following results: (1) The m=0 mode oscillation of plasma density is predominant in oscillistor oscillation, and (2) the helical mode oscillation is excited at larger magnetic field or current than that of the m=0 mode oscillation. (3) The terminal voltage oscillation is equivalent to the m=0 mode oscillation. (4) The oscillation is excited only in a limited region 2–4 mm from the injecting junction, and this density oscillation travels along the drift direction of the minority carriers. (5) The drift velocity of the density wave increases with the distance from the exciting position.
Oscillation (cell signaling)
Upper hybrid oscillation
Mode (computer interface)
SIGNAL (programming language)
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Correct judgment of the oscillation mechanism has a great significance in rationally selecting the oscillation suppression measures and quickly suppressing the oscillation when a grid low-frequency oscillation occurs.Based on the actual measured data of wide area measurement system(WAMS),this paper analyzes the characteristics of the negative damping oscillation and the forced power oscillation in the pre-oscillation,the transient stage,the steady-state stage,and the decay stage,and studies the method of discriminating the negative damping oscillation from the forced power oscillation in different stages.Through the comparative analysis of two actual cases occurring in the grid,the conclusions of the theory analysis are verified.
Oscillation (cell signaling)
Low-frequency oscillation
Transient (computer programming)
Forced oscillation
Power grid
Upper hybrid oscillation
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The variation characteristics of electrical variables and the variation pattern of oscillation centre in multi-source oscillation scenes are revealed, and a desynchronising centre positioning method is proposed. First, based on the multi-source oscillation model, the expressions of voltage and current in multi-source oscillation scenes are derived. And then, according to the definition of oscillation centre, the oscillation centre position function is constructed, as a quantitative description of the position of oscillation centre. On this basis, the impacts of power angle variation trend (oscillation mode), system operation mode variation and unequal emf amplitudes on the oscillation centre are analysed. Simulation results demonstrate that, the oscillation mode is the main factor that affects the drifting pattern of oscillation centre, system operation mode is the main factor that determines the drifting boundary of oscillation centre, and unequal emf amplitudes cause the oscillation centre to deviate towards the side with lower amplitude. Finally, according to the relationship between system emfs when the desynchronising centre appears, the desynchronising centre position function is derived, so that the position of desynchronising centre can be identified. Simulation results on Real Time Digital Simulator of multi-machine system verify the correctness of the analysis results.
Oscillation (cell signaling)
Position (finance)
Low-frequency oscillation
Mode (computer interface)
Upper hybrid oscillation
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Based on the SS-model [Somogyi R and Stucki J W J. Biol. Chem. 266 (1991) 11 068] for the generation of intracellular Ca2+ concentration oscillations, we consider a time delay for the binding kinetics of the Ca2+ channel and find a significant phenomenon that the oscillation takes two quite different modes when a parameter of the system crosses a threshold. One is a quick oscillation mode and the other is a slow oscillation mode. The oscillation frequencies of these modes differ from each other by more than ten times. The change of oscillation form with parameters and its critical behaviour are illustrated by numerical simulation results.
Oscillation (cell signaling)
Mode (computer interface)
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A model on non-sinusoidal oscillation of continuous casting mould was established to study the pressure in flux channel. The effects of oscillation parameters on the pressure in flux channel were researched. The non-sinusoidal oscillation parameters were optimized. When the casting speed is 1.8 m·min -1 , the optimized oscillation parameters are: non-sinusoidal factor (α) is 0.198, oscillation amplitude ( s ) is ±4mm and oscillation frequency ( f ) is 165min -1 . When the casting speed is 2.0 m·min -1 , the optimized oscillation parameters are: α is 0.186, s is ±4.5mm and f is 155min -1 . These optimized oscillation parameters are proved applicable in practice.
Oscillation (cell signaling)
Non-sinusoidal waveform
Upper hybrid oscillation
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Current oscillation and potential oscillation in a semiconductor with a dumbbell-shaped structure are observed, and the mechanisms of the oscillations are investigated by varying the magnitude of the carrier densities. It is shown that a certain amount of the carrier densities are necessary to cause the current oscillation and that the potential oscillation is observed by pressing the probe on the surface of the narrow region even if the current oscillation of the narrow region is not observed.
Oscillation (cell signaling)
Upper hybrid oscillation
Dumbbell
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Oscillation (cell signaling)
Upper hybrid oscillation
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