Cycling frequency

The fatigue strength of most TPs is about 20 to 30% of the ultimate tensile strength determined in the short-term test but higher for RPs. It decreases with increases in temperature and stress-cycle frequency and with the presence of stress concentration peaks, as in notched components. 

When Reuben et al., measured the hourly secretion rates of phospholipids, bile acids and cholesterol in obese and nonobese individuals with and without cholesterol gallstone disease, they found that the pattern of results was quite different in the obese and the nonobese gallstone carriers. The obese had hypersecretion of cholesterol but normal bile-acid output, while the nonobese had normal cholesterol secretion but a reduced bile-acid output. The authors speculated that the most likely explanation for the high biliary cholesterol secretion rates in the obese was their increased total body cholesterol synthesis. Conversely, nonobese gallstone carriers often have a reduced total bile-acid pool size, and if the enterohepatic cycling frequency of this small bile-acid pool remains unchanged (controversial), it could explain the reduced bile-acid secretion rate seen in the normal weight (nonobese) individuals. 

Moreover, for patients who show a wide range of cycle frequencies (as is typical for bipolar illness), this strategy is likely to avoid many of the pitfalls associated with a high rate of placebo response, actually attributable to the natural course of illness and highly predictable on the basis of systematic retrospective and prospective life charting (Post et al. 1988 Squillace et al. 1984). 

Simulator SPICE file Duty cycle (%) Frequency (kHz) Run time (s)... 

Most elastic elements will have a service life of close to a million cycles, if the cycle time is not less than 5 seconds. If longer service life or higher-cycle frequencies are required, metal fatigue tends to limit the usefulness of elastic elements, and special designs, such as sealed piston elements, should be considered. 

Figure 3 was calculated from steady-state measurements. Curvature of the rate vs composition relation causes the quasi steady-state rate to be well below the steady-state reactor performance. This emphasizes the very large effect of cycling frequency on the time average synthesis rate. 

The model predicts rate oscillations over a rather wide range of parameters A. It was verified that for given feed composition, space velocity and reactor temperature the predicted limit cycle frequency and amplitude do not depend on the initial conditions of the numerical integration. 

The rate oscillations produced by the model are always simple relaxation type oscillations (Fig. 5). The model cannot reproduce the rather complex oscillation waveform which was observed experimentally under many operating conditions (Fig. 1). However the model predicts the correct order of magnitude of the limit cycle frequency and also reproduces most of the experimentally observed features of the oscillations figure 2 compares the experimental results of the limit cycle frequency and amplitude (defined as maximum % deviation from the average rate) with the model predictions. The model correctly predicts a decrease in period and amplitude with increasing space velocity at constant T and gas composition. It also describes semiquantitatively the decrease in period and amplitude with increasing temperature at constant space velocity and composition (Fig. 3). 

The importance of potential sweep limits on the processes involved in thick oxide growth at Ir was demonstrated by Burke and co-workers [121, 136]. The optimum range at moderate cycling frequencies (1-10Hz) in acid involves a lower limit of about 0.025 V and an upper limit of 1.55 V (RHE). According to these authors, exceeding this upper limit results in dissolution of the oxide film, while exceeding the lower limit of 0.025 V reduces the rate of oxide formation. 

FIGURE 7.10 Effect of load cycle frequency on fatigue crack growth rate (daldN) vs. stress intensity factor range (AK) relationships for a carbon steel. ... 

Recurring cycles may be missed if sampling intervals happen to coincide with the cycle frequency, in which case only the low or high range of the cycle may be... 

D. Bocker, R.D. Gonzalez, In Closed-Cycle, Frequency-Stable CO2 Easer Technology, NASA Conf. Publication 2456, C.E. Batten, I.M. Miller, G.M. Wood, Jr., D.V. Willetts, eds., 1987, pp. 85-102. 

Fig. 2.1.5. The relative cycling frequency of an average carbon atom within the atmosphere, biosphere and hydrosphere (exogenic cycles) relative to the cycling in the litho-spere (endogenic cycles).

The conventional use of meteorology will be most important during the construction period at a site. On some projects it may be necessary to furnish climatological data for prospective bidders, seasonal work scheduling, and on information not commonly available, such as freeze-thaw cycle frequency, and annual wet-bulb temperature frequencies and ranges. 

The ability of the catalysts to supply oxygen for the oxidation of CO and HCs when the exhaust is fuel-rich, and to remove excess oxygen when it is lean is evidenced in the light-ofF tests under cycling conditions. We chose a low cycling frequency (0.1 Hz) between two... 

The interesting point is the comparison of the light-off activity under stationary or oscillating compositions (table 4). It is clearly seen that, despite the low cycling frequency chosen (the rich and lean feedstreams are switched for each other every 5 seconds), the catalysts show no loss of activity when compared with the light-off tests under stationary composition. 

Here / is the cycle frequency, Nf the number of cycles to failure, and AT the temperature difference. The Coffin-Manson model is widely accepted for describing material degradation (e.g., solder materials), fatigue fracture, and crack propagation. 

Cambier In your simulations, you vary cycle frequency however, cycle frequency is not a free parameter in practice. 

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