Undershooting

Impact of a thin plate on a sample of interest which is, in turn, backed by a lower impedance window material leads to an interaction of waves which will carry an interior planar region into tension. Spall will ensue if tension exceeds the transient strength of the test sample. A velocity or stress history monitored at the interface indicated in Fig. 8.4 may look as indicated in Fig. 8.5. The velocity (stress) pull-back or undershoot carries information concerning the ability of the test material to support transient tensile stress and, with appropriate interpretation, can provide a reasonable measure of the spall strength of the material. 

Question 2 Is my equipment somehow responsible That is sadly often the case. For example, some electronic loads can show weird glitches in the load profile they present to the converter under dynamic conditions. For example, if we are doing step load testing from 10mA to 200mA, all may be fine. But if we go from 0mA to 200mA, and see an output overshoot/undershoot, it could also be because of the electronic load. We may need to do... 

Specifically, Figure 16 shows that the current density in a cell with dry cathode gas feed drops nearly instantaneously once the cell voltage is relaxed from 0.6 to 0.7 V due to the fact that the electrochemical double-layer effect has a negligibly small time constant. Further, there exists undershoot in the current density as the oxygen concentration inside the cathode catalyst layer still remains low due to the larger consumption rate under 0.6 V. As the... 

UNCOMPETITIVE INHIBITION UNCONSUMED SUBSTRATE OR COFACTOR UNDERSHOOT Unfacilitated transport rate,... 

Appreciable pressure overshoots and undershoots are noticeable. The pressure trace at the end of the runner system (P2) at lower levels follows the pattern of the nozzle pressure. 

Set the integral and derivative constants to a minimum so that the proportional band may be adjusted first. The proportional band should be set as tightly as possible so long as there is no indication of on-off oscillation. The derivative function should then be increased, which should act to minimize over-shoot/undershoot during a sharp change in thermal schedule or on initial startup. Increasing the derivative constant too much... 

Considerable difficulty was experienced throughout the entire period of plant-scale operation of the DBBP countercurrent extraction process in adjusting the CAW solution to the desired pH of 0.75. Several factors contributed to these difficulties. Lack of any buffering capacity in the CAW solution made it easy to overshoot or undershoot the desired pH. The two-step neutralization procedure and equipment aided considerably in achieving proper feed acidity. But, even with this approach, inadequate mixing coupled with unsophisticated and insensitive monitoring and control instrumentation made it impossible to routinely achieve reliable adjustment of feed acidity to its optimum range. 

The result for the thermal expansion coefficient, a, which is equal to (dV/dT)/V, is shown in Fig. 13.36 for the cooling and heating process. In the cooling process a decreases gradually from tq to ag. Hysteresis in the volume causes in the subsequent heating process an anomalous effect in the thermal expansion coefficient, depicted by undershoot and overshoot, as also shown in Fig. 13.36. A similar effect occurs in enthalpy H and accordingly in cp, the specific heat capacity, equal to dH/dT. This effect is frequently observed in DSC (Differential Scanning Calorimetry) experiments. 

The velocity aloi the symmetry axis is significantly different an overshoot at the contraction as well as an undershoot downstream of the die exit are observed with the generalized Oldroyd-B model, but only a smooth overshoot is indicated by the multimode Phan-Thien Tanner model. The final value of the velocity after swelling is more important for the PTT, which is consistent with the lower value of swelling observed in Fig 20. 

It is worth mentioning that the rate constant for the reaction of OH radical with H2, which is one of the most important reactions in water chemistry, has also been studied up to 350°C by competition kinetics using nitrobenzene as a competing OH scavengerd At higher temperatures, the rate constant undershoots an extrapolation of the Arrhenius plot and actually decreases in value above 275°C. At 350°C, the measured rate constant is more than a factor of five below the Arrhenius extrapolationd This implies that the amount of hydrogen injection calculated by the current model of water radiolysis in nuclear reactor should be reconsidered. 

Figure 10.2. Various phases of the action potential. Once a depolarization reaches a certain threshold, the membrane potential moves rapidly in a regenerative manner toward The opening of K channels coupled with the inactivation of Na channels causes the membrane potential to repolarize. The prolonged hypeipolaiization (undershoot) results from slow closing of open K channels following rapid repol aiization.

Tlie undershoot of an action potential occurs from... 

The scaling, Eq. (9-48), also implies that time-dependent stresses can be rescaled so that data taken at different shear rates collapse onto a single curve. Consider an example in which the sample is sheared at a rate yt until a steady state is reached, and then the shear rate is suddenly increased by a factor of four to y/ — 4yi. After this increase in shear rate, the shear stress undergoes an overshoot and an undershoot, while the first normal stress... 

Although this experimentally observed scaling behavior is correctly predicted by the Doi-Ohta theory, the shape of the transient response curve—in particular, the overshoot and undershoot in the shear stress—are not predicted. This implies that the relaxation expressions chosen by Doi and Ohta, Eqs. (9-46) and (9-47), are inaccurate. This is not very surprising, since Eqs. (9-46) and (9-47) were chosen rather arbitrarily from many possible forms that satisfy the scaling relationship. Optical microscopy suggests that the overshoot and undershoot are caused by elongation of droplets followed by their breakup (Takahashi and Noda 1995). Vinckier et al. (1997) have shown that the stress growth after start-up or... 

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