Voltage oscillations

Figure 14.8 (a) A voltage oscillation obtained for Zn electrodeposition from an ultra-thin electrolyte, (b) SEM images of the Zn deposit obtained under the voltage oscillation. (Reprinted from Ref [27] with permission from John Wiley, Sons Ltd.)... 

September 2000 Hi, I have been designing my power supply with the 2595, in continuous mode of operation for 1A of load current. I am expecting that my load can drop to 5mA at some points during the operation. It may stay at 5mA for a while. What effect will the low load have on my output voltage ripple, and can the output voltage oscillate ... 

The frequency analyser then alters the frequency at which the voltage oscillates and Z is determined once more, with this procedure being performed for as many as 50 different frequencies. (It is the usual practice to start at the upper frequencies and progress down to the lower frequencies.)... 

The circuit was constructed in the laboratory. The values of Rl, R2, Cl, and C2 are the actual measured values of the components used in the circuit. A Tektronix TDS 340A digital real-time oscilloscope was used to record the output data, as shown in Fig. 8.2. The duty cycle was calculated to be 66.7%, and the output voltages oscillated from 5 V to 10 V. The simulated data, from IsSpice, Micro-Cap V, and PSpice, are shown in Figs. 8.3, 8.4, and 8.5, respectively. Table 8.1 illustrates the variances in the simulated output data. 

C. Morris and H. Lecar Voltage oscillations in the barnacle giant muscle fiber. Biophys.J. 1981, 35 193-213. 

Frequency — In general, frequency is the rate at which a happening or phenomenon recurs, measured as the number of cycles or completed alternations per unit time. In electrochemistry, it usually refers to the number of complete cycles per second in some periodic current or voltage oscillation. Such oscillations are often sinusoidal in shape, but may have other wave shapes such as square wave, triangle wave, etc. The frequency / (in cycles per second or hertz, Hz) is equal to the reciprocal of the period of the waveform ]> (in s). The period ( ]>) is the time required to complete one complete cycle of the oscillation, as illustrated for a sine wave in the figure below (where Tp = 0.100 s). 

Related phenomena are voltage oscillations at Ag/AgI contact observed in Ref.275 periodic bands in precipitation reactions (Liesegang phenomenon)177 or oscillations involving proton conductors.276... 

An electric noise can induce switching of a ring segment into the normal state when its current amplitude /q exceeds the critical current 7 (7) = /c(0)(l -777 c). Since the 7 (7) decreases down to zero at 7 7 a weak noise can induce the dc voltage oscillations near Tc- The amplitude of the Fdt(< <2b)... 

J. Carstensen, R. Prange, and H. Foil, A model for current voltage oscillations at the silicon electrode and comparison with experimental results, J. Electrochem. Soc. 146, 1134, 1999. 

However, in all other respects, flows on the circle are similar to flows on the line, so this will be a short chapter. We will discuss the dynamics of some simple oscillators, and then show that these equations arise in a wide variety of applications. For example, the flashing of fireflies and the voltage oscillations of superconducting Josephson junctions have been modeled by the same equation, even though their oscillation frequencies differ by about ten orders of magnitude ... 

Josephson junctions are superconducting devices that are capable of generating voltage oscillations of extraordinarily high frequency, typically 1O —10" cycles... 

Current and voltage oscillations) Consider a Josephson junction in the overdamped limit j3 = Q. 

Fig. 5.15, Chaotic bifurcation diagram of the resonasit tunneling diotie. The maxima and minima of tlie voltage oscillations are plotted versus the time-scale parameter e, [47]...

A. A. Kulikovsky, H. Scharmann, and K. Wippermann. On the origin of voltage oscillations of a pol mer electrolyte fuel cell in galvanostatic regime. Electrochem. Comm., 6 729-736, 2004. 

The numeric data can be found in Table 3.3. The third term in Eq. (3.18) is empirical and reflects the interesting behavior of the oscillations frequency for different formic acid concentrations. Other terms are similar to the ones described in Strasser et al. (1997). However, some values were adjusted to get realistic simulation results. Measured voltage oscillations compared to the simulation data are shown in Fig. 3.25. The simulation does not require any change in boundary or initial conditions for the basic model, which is described in the previous subsection. However, equations (3.12), (3.13), (3.14), and (3.18) were simulated using the weak-form differential equation on the anode boundary. 

The oscillations resulting from coupled competing processes need not just involve a temporal change of concentration. Diffusion, temperature, and voltage also couple with chemical reaction resulting in concentration waves, temperature oscillations, or voltage oscillations. Under special conditions a system may even be stable in more than one stationary state and, as a system evolves, a chemical hysteresis can be observed. 

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