Present Value Time-Line Analysis

Off-line analysis of stored data review of the stored data, organize data in different presentation windows, plot AE and plant parameters data so as to enable comparison and coirelation with the possibility to present data (histogram of AE events vs position, plant parameters and/or AE parameters vs time) conditioned in terms of time interval (initial time, final time) and/or position interval (defined portion of the component = initial coordinate, final coordinate) and/or plant parameters intervals (one or more plant parameters = initial value, final value). 

Kivelson and Niemann [301] showed that both An and gn correlate well with the type of ligand atoms bound to Cu2+ and with the polyhedron structure [301-303]. Therefore, changes in the EPR spectrum shape and parameters have to reflect rearrangements in the coordination sphere. Fig. 8.22 presents typical EPR spectra of Cu(II) complexes adsorbed onto nanocrystalline Ti02 particles from solutions containing Cu(N03)2 and edta at the ratio [Cu] [edta] = 1 1 at different pH values. The line-shape analysis showed that at pH 2.9 and 8.0 the EPR spectra are a superposition of the spectra of at least two different species, while the spectrum, recorded for the sample prepared at pH 6.9 with a short (1 h) time of adsorption, indicates the formation of only one Cu2+ species at the surface (type A ). 

One way to get a representative product distribution for a specific period is to remove all FT products in the reactor system and replace them with a substance that will not influence selectivity determination. The FT reaction is then run for a specific period, after which a full analysis can be done that will represent only the products produced during that specific period. In Figure 13.8, data are presented for a run started with the catalyst suspended in a highly paraffinic wax (FT HI wax, C30-C90). After a certain time of synthesis, the FT run was stopped and the catalyst placed under inert conditions (argon). The reactor content was then displaced with degassed and dried polyalphaolefin oil (Durasyn). After restarting the FT synthesis, the total product spectrum was determined (HI run after displacement). It was found that the value of a2 was much lower than before the displacement of the HI wax. In fact, the a2 values were quite comparable to those measured when the FT synthesis was started up with Durasyn (compare with Durasyn runs 1, 2, and 3). This clearly illustrates the impact that the reactor medium used to start the FT reaction can have on the determination of the a-value. The results further show that there was no change in the value of a2 of the iron catalyst up to 500 h on-line. 

Clearly flow aligning behavior of the director is present and do increases linearly with the tilt angle, do. Above a threshold in the Spain rate, y 0.011, undulations in vorticity direction set in. In Fig. 14 the results of simulations for y 0.015 are shown. In Fig. 15 we have plotted the undulation amplitude obtained as a function of the shear rate. The dashed line indicates a square root behavior corresponding to a forward bifurcation near the onset of undulations. This is, indeed, what is expected, when a weakly nonlinear analysis based on the underlying macroscopic equations is performed [54], In Fig. 16 we have plotted an example for the dynamic behavior obtained from molecular dynamics simulations. It shows the time evolution after a step-type start for two shear rates below the onset of undulations. The two solid lines correspond to a fit to the data using the solutions of the averaged linearized form of (27). The shear approaches its stationary value for small tilt angle (implied by the use of the linearized equation) with a characteristic time scale t = fi/Bi. 

At constant AP a plot of 6bP/(V/A) vs. V/A should give a straight line with a slope equal to ff wg(AP)J/2 and an intercept at V/A = 0 of a w VFUiP)s. Figure 14-59 presents a plot of this type based on the experimental data for this problem. Any time the same variable appears in both the ordinate and abscissa of a straight-line plot, an analysis for possible misinterpretation should be made. In this case, the values of 9 and AP change sufficiently to make a plot of this type acceptable. 

The precision of the technique for seawater analysis as presented in the literature (i, 5) tends to be considerably better than we have observed here. The values obtained in other papers were for duplicate analysis of the same sample and were most likely extracted sequentially from the same bulk sample and analyzed one directly after the other. This was not the case here because the data analyzed in this paper were not generated specifically to analyze the ultimate precision of the technique. Line water samples run normally were as a rule interspersed throughout the test samples. A number of water samples would be drawn at the start of an experiment and stored unacidified in 4-1. polypropylene bottles. Over the course of up to 6 or 8 hr, extractions would be performed so that difiFerences in trace metal concentration might be expected between replicates run early and late in the experiments. This factor, which allows for significant adsorption and/or desorption of trace components, could readily explain our high standard deviations. We feel that this approach is valid to determine the precision of the technique in the field where non-optimum conditions often occur and where the factor of time between sampling and analysis is often an uncontrollable variable. It is likely that the actual precision of this technique in the field lies between those values calculated here and elsewhere (1,5). 

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