Estimation of true moments from truncated data

Abstract

Moment analysis is a powerful tool in reactor bed analysis. Weighted moments is a technique which has been introduced to increase the accuracy of moment estimation. The supposed advantage of weighted moments is reevaluated utilizing an optimum truncation point. The resulting coefficient of variation in the moment estimates is shown to be superior to an arbitrary truncation point for all weighting factors. When an optimum truncation pcint is used, little advantage is observed for weighted moments.

Vapor-phase transport of trichloroethene in an intermediate-scale vadose-zone system: Retention processes and tracer-based prediction

“…For some data sets, the elution curve was truncated. A log-linear tail extrapolation was conducted for these cases to enhance the accuracy of moment analysis (e.g., Skopp, 1984; Deeds et al, 1999b). The data were extrapolated to a common point of elution, C/C 0 = 10 −4 .…”

Estimation of the transfer function, time moments, and model parameters of a flow process

“…The result of this approach is inherently approximate, due to the necessary truncation of the infinite sum Eq. 2 (Skopp, 1984) and the accumulation of round-off errors in using Eq. 14.…”

“…A major problem in this approach is that a perfect impulse cannot be realized in practice. Further, the dynamics of the source that generates the impulse and of the sensor are included in the result, and the accuracy of the result is limited by disturbances such as sensor noise, especially in the tail end of the response (Skopp, 1984). To reduce the effects of disturbances, one would have to gather more data by repeating the experiment.…”

Quantifying uncertainty due to random errors for moment analyses of breakthrough curves

“…With this qualification, direct integration using the trapezoidal rule to estimate moments from BTCs is advantageous due to its simplicity. Skopp (1984) stated that the accurate estimation of moments is prevented for two reasons. 'First, the data obtained is (sic) invariably noisy; second, at some point the data must be truncated'.…”