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Soner Bekleric Title of Thesis: Nonlinear Prediction via Volterra Ser

Soner Bekleric Title of Thesis: Nonlinear Prediction via Volterra Ser

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4.5. SYNTHETIC AND REAL DATA EXAMPLES 64<br />

prediction <strong>of</strong> data using a third-order <strong>Volterra</strong> series with parameters p = 3, q = 3,<br />

and r = 3. Figure 4.12(c) shows the error between the observed data and predicted<br />

data <strong>via</strong> a third-order <strong>Volterra</strong> series. Figures 4.12(d) and 4.13(b) depict predictions<br />

<strong>of</strong> the data using linear prediction theory with parameter p = 3. In Figures 4.12(e)<br />

and 4.13(c) I portray the difference between original data and predicted data using<br />

the linear prediction method. Figure 4.13(d) illustrates the prediction <strong>of</strong> data using<br />

the cubic part <strong>of</strong> a <strong>Volterra</strong> series with parameter r = 3. Figure 4.13(e) shows<br />

the error between original data and predicted data using only the cubic part <strong>of</strong> a<br />

<strong>Volterra</strong> series. The cubic part <strong>of</strong> a <strong>Volterra</strong> series yields a prediction similar to the<br />

linear prediction theory. In Figure 4.14 I portray the individual contributions <strong>of</strong> a<br />

<strong>Volterra</strong> series to the prediction <strong>of</strong> data. The contribution due to the linear terms <strong>of</strong><br />

the <strong>Volterra</strong> series to the predicted data in Figure 4.14(b) is shown in Figure 4.14(c).<br />

It can be seen that the data are predicted mostly with linear terms. Figures 4.14(d)<br />

and 4.14(e) show the parts <strong>of</strong> the prediction associated with the quadratic (q = 3)<br />

and cubic (r = 3) terms in a third-order <strong>Volterra</strong> series. The contribution <strong>of</strong> the<br />

quadratic part is negligible to the prediction <strong>of</strong> the data; the contribution <strong>of</strong> the<br />

cubic part is relatively better than the quadratic part. Figure 4.14(f) shows the<br />

contribution <strong>of</strong> nonlinear terms associated with quadratic and cubic terms (q = 3<br />

and r = 3). These examples confirm that waveforms with linear moveouts can be<br />

predicted using linear prediction theory and cubic <strong>Volterra</strong> prediction.<br />

Figures 4.15(a) and 4.16(a) show a 2-D synthetic data example with hyperbolic<br />

events. These events have been synthesized using a forward apex-shifted hyperbolic<br />

Radon transform (Hargreaves et al., 2003; Trad, 2003). In Figure 4.15 a comparison<br />

between linear prediction theory and the third-order <strong>Volterra</strong> series is illustrated.

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