Some Typical Transients

LOCAs may be further subdivided into large, intermediate, small, and very small depending on the injection systems required to successfully respond to the LOCA. Transients initiators are usually events related to the balance of plant (BOP). Some typical transient initiators are listed for BWRs and PWRs in Tables 2.2-1 and 2.2-2. These transients are explicitly considered in probabilistic risk assessments, as discussed in Section 2.6. Note that these initiators are somewhat more specific than the design-basis initiators presented in Table 2.1-2 and include more events, although there is some overlap in the respective lists. 

Figure 8.40 shows some typical galvanostatic transients, one for I>0 and another for I<0. In the former case (Fig. 8.40a) both rates of C2H40 and C02 formation increase but both exhibit an initial "overshooting". 

Figure 2 plots the evolution of the incoming fluxes Jm and with time for some typical values from the literature [24,25] and references therein. As expected, the diffusive flux Jm decreases with time and tends towards a steady-state value when converging with Ju. It is noticeable that, in the initial transient, the internalisation flux Ju is much closer to its eventual steady-state... 

With typical values for R and D as above, the Smoluchowski rate coefficient (19) is shown in Fig. 3 for a range of times. The time dependence of the rate coefficient is due to the transient concentration of B in excess of the steady-state concentration. As the density distribution of eqn. (16) relaxes to the steady-state distribution (17), so the rate coefficient decreases, because at longer times, B has to diffuse further to A on average. The magnitude of the rate coefficient ( 1010 dm3 mol-1 s-1) is large. In some reactions, the mutual diffusion coefficient of reactants may be nearer 5 x 1CT9 m2 s 1, and the rate coefficient is 3 x 1010 dm3 mol-1 s-1. Under such circumstances, diffusion-limited reactions proceed very rapidly. It is likely that the rates of most chemical reactions are slower than the diffusion-limited rate. Only the most rapid molecular chemical reactions are faster than diffusion-limited rates. Some typical reactions are discussed in Sect. 2 and will be reconsidered in Sect. 5 and later in the volume. 

Figure 24.24 illustrates some typical experiments of transients for the I2 Ne(v ) l2(v — 1) -f Ne photodissociation. Three cases are shown, namely for v[ = 13,18and23, whose lifetimesare216ps, 107ps, and 53 ps respectively. 

In some cases, magnetically induced transient twist distortions have been observed in both thermotropic (MBBA [89]) and lyotropic (PBG [90]) systems. In this case, backflow effects are allowed only in a nonlinear regime, for strong distortions. The physical origin of this phenomenon could be the faster response times of modulated structures, as compared with uniform ones. When the equilibrium director distribution is approached, i.e. a relaxation process is over, the transient structures disappear. The emergence and subsequent evolution of the spatial periodicity of the transient structures have been considered theoretically [89,90]. In addition, the pattern kinetics have been studied in detail experimentally [91] on a mixture of a polymer compound with a low-molecular-mass matrix. The polymer considerably increases the rotational viscosity of the substance and reduces the threshold for pattern formation. This indicates the possibility of recording the pattern using a video camera. A typical transient pattern is shown in Fig. 14 [91]. 

Figure 56 shows some typical galvanostatic transients, one for / > 0 and another for / < 0. In the former case (Fig. 56a), both rates of C2H4O and CO2 formation increase, but both exhibit an initial overshooting. The latter case (Fig. 56b) is more interesting. Initially, both rates decrease, but at steady state the rate of epoxidation has decreased while the rate of CO2 formation has increased. Thus, epoxidation exhibits electrophobic behavior but oxidation to CO2 exhibits electrophilic behavior." ... 

Noise may be generated by processes within the seismometer or by external processes acting on the seismometer. Some noise is expected or unavoidable, such as the manufacturer s characterized self-noise, or may be indicative of instrument defects such as persistent spurious transient noise event ( pops ) or installation deficiencies such as thermally driven noise or the seismometer shifting or tilting. It is first useful to review some typical sources of internal and external noise. 

In these plots the thermodynamic quantities go through some initial transient behavior, and then eventually settle down into small-amplitude oscillations. At this very low temperature both U and Cy settle down rapidly and they do so on similar timescales. Typically, the running averages of U and Cy will not converge simultaneously. In fact Cy will usually be the slower of the two to converge, since its fluctuations arise from fluctuations of the... 

Electron injection dynamics in the conduction band of metal oxide materials from dye molecules or metal nanoparticles, which is important when applied to sensitized solar cells, can be monitored in the infrared by 100 fs time resolution. In this chapter, technical details of femtosecond visible-pump/IR-probe transient absorption spectroscopy and some typical spectroscopic data revealing the mechanism of electron injection process were described. A great advantage of this technique is that one can observe transient absorption of injected electrons easily because of the intense intraband transition of an electron at the bottom of or at the trap level just below the conduction band of the metal oxide that forms an electrode. In the case of dye-sensitized solar cells, the effects of metal oxide, dye, solvent and additive ions on the rate and efficiency of electron injection were discussed in detail. One recent discovery, plasmon-induced electron injection from a gold nanoparticle to a Ti02 nanoparticle, was presented to show how femtosecond visible-pump/IR-probe transient absorption spectroscopy is useful in studying this kind of new charge transfer dynamics in a nano-structured system. 

Under some conditions, it is observed that complex oscillatory sequences develop even in batch systems, typically towards the end of the oscillatory phase of the reaction. Transient chaos —see section A3.14.3.3— appears to be established [18]. 

Electrothermal vaporization can be used for 5-100 )iL sample solution volumes or for small amounts of some solids. A graphite furnace similar to those used for graphite-furnace atomic absorption spectrometry can be used to vaporize the sample. Other devices including boats, ribbons, rods, and filaments, also can be used. The chosen device is heated in a series of steps to temperatures as high as 3000 K to produce a dry vapor and an aerosol, which are transported into the center of the plasma. A transient signal is produced due to matrix and element-dependent volatilization, so the detection system must be capable of time resolution better than 0.25 s. Concentration detection limits are typically 1-2 orders of magnitude better than those obtained via nebulization. Mass detection limits are typically in the range of tens of pg to ng, with a precision of 10% to 15%. 

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