Bursts, intermittent

Chemical reaction network is a typical example of complexity, where the reactants can interact in a variety of ways depending on the nature of interaction (chemical as well as non-chemical). Oscillatory reactions involve a number of steps, including positive and negative feedbacks. The complexity leads to periodic as well as aperiodic oscillations (multi-periodic, bursting/intermittency sequential oscillations separated by a time pause, relaxation and chaotic oscillations). The mechanism is usually determined by non-linear kinetics and computer modelling. Once the reaction mechanism has been postulated, the non-linear time-dependent kinetic equation can be formulated in terms of concentrations of different reactants, which would yield a multi-variable equation. Delay differential equations are sometimes used to characterize oscillatory behaviour as in economics (Chapter 14). 

Mode of release (single burst, intermittent, continuous) ... 

The second method could be automatic intermittent blowdown. With this, a timer-controlled valve is installed at the bottom of the boiler prior to the main blowdown valve. A program is then designed to operate this valve in short bursts, which disperses any sludge and controls the levels of solids. This method is preferred for boilers having internal treatment. 

The final estimation of the value of ay may appear tedious and several assumptions are made in its derivation, but experimental evidence suggests that it may be used with reasonable accuracy to assess the levels of potentially damaging cavitation erosion. In small valves with nominal bores up to 65 mm cavitation inception occurs in intermittent bursts when the value oy is approximately unity. The cavitation becomes continuous and audible as Oy is reduced to about 0.6, but the risk of damage does not become significant until the value falls below 0.4. As a design criterion the condition of light, steady noise has been described by Tullis as the critical level and is sug-... 

It is worthwhile to note here that in Figs. 3 and 4 the current densities measured at a methanol and air flow rates of 2 ml/min and 2 L/min, respectively show the inconsistency even at the same operating conditions. The reason is expected to be due to the water produced at the cathode. Comparing Figs. 3 and 4, the measured current density response looks quite unstably scattered at low air flow rates in Fig. 3, while it seems to be stable even at the low methanol flow rates in Fig. 4. This instability of measured current density in Fig. 4 could have caused by the water formed at the cathode during the operation of the stack. In fact, it has been observed from the experiment that the water produced at the cathode looks accumulated in the cathode flow channels for a while and it bursts out intermittently to the cathode outlet. Based on the experimental observations, for the stable operation of the 5W... 

Most team games (e.g. soccer, rugby, hockey, football) and some individual sports (e.g. squash, tennis) involve intermittent high-intensity bursts of exercise interspersed with rest periods (i.e. mostly less intense periods), although the whole period of activity can be very long. These are known as multiple sprint sports. In experiments that involved a study of short bursts of activity followed by short rest periods, repeated for 30 minutes, the increase in blood... 

Fig. 9.6. Details of the solenoid stirrer. If the solenoid is wound with 2 lb of 22-gauge magnet wire, it will withstand 115 V in intermittent bursts. The current interrupter, shown above, involves a cam which opens and closes a microswitch.

As noted, a high degree of voidage fluctuation is associated with the bursting of wavy solids layer into clusters. The intermittency of the bursting and the cluster velocity are elaborated in the following. 

Complicated Reactions and Flow. The ideal turbulence model must deal with multiscale effects within the subgrid model. If there is a delay as velocity cascades to the short wavelength end of the spectrum due to chemical kinetics or buoyancy, for example, the model must be capable of representing this. Otherwise bursts and intermittency phenomena cannot be calculated. 

Wang, X.J. Multiple dynamical modes of thalamic relay neurons rhythmic bursting and intermittent phase-locking. Neuroscience 1994,59 21-31. 

In experimental systems, intermittency appears as nearly periodic motion interrupted by occasional irregular bursts. The time between bursts is statistically distributed, much like a random variable, even though the system is completely deterministic. As the control parameter is moved farther away from the periodic window, the bursts become more frequent until the system is fully chaotic. This progression is known as the intermittency route to chaos. 

The intensity of the emitted laser light is plotted as a function of time. In the lowest panel of Figure 10.4.5, the laser is pulsing periodically. A bifurcation to intermittency occurs as the system s control parameter (the tilt of the mirror in the laser cavity) is varied. Moving from bottom to top of Figure 10.4.5, we see that the chaotic bursts occur increasingly often. 

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