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Annual Report 2000 - WIT

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È<br />

Û Ñ¿ = ¨ Í<br />

Ñ>*<br />

=<br />

¿ + ð<br />

ð<br />

ô<br />

¼<br />

¿<br />

»ÀB¦É¾ ¸ » ¸<br />

<br />

ô<br />

Ë<br />

ð<br />

Ó<br />

Ë ¼<br />

¹<br />

¾¿ + ©<br />

ð ò íî¨ï<br />

ì ê<br />

» <br />

§<br />

õ<br />

ð<br />

¼<br />

.<br />

ð<br />

ó<br />

ç<br />

ð<br />

ô<br />

ô<br />

§<br />

Ñ9<br />

óžô<br />

» ¸<br />

<br />

ô<br />

À<br />

» À/¦É¾ ¸<br />

ð<br />

*<br />

ó<br />

ð<br />

õ<br />

õ<br />

§<br />

»<br />

õ<br />

2<br />

ð<br />

ð<br />

ð<br />

À<br />

õ<br />

À<br />

À<br />

ó<br />

à<br />

ð<br />

ð +<br />

ð<br />

ô<br />

õ<br />

§<br />

Þ<br />

ð<br />

ó<br />

ð<br />

õ<br />

ô<br />

»ÀA¦É¾ ¸<br />

¨ ð<br />

Ñ>*<br />

»À/¦É¾ ¸ ¾ Þ ð<br />

ì<br />

<<br />

¼<br />

Þ<br />

¼<br />

<br />

73<br />

To make use of the simmetry of the 2.5D situation, we transform integral (A-6)<br />

into the frequency domain, where it reads<br />

¸ ¢ ¾ ¢<br />

Ä Å Â¨Ã<br />

à Å È<br />

Here, denotes the Fourier transform of .<br />

Ï <br />

The isochron ½ ¿]Ñ ¸ »¤¼<br />

Ë ¼<br />

¹<br />

ê ©<br />

Ë ¼<br />

¹<br />

¾) Þ Ç<br />

(A-7)<br />

·5¸ »¤¼¢ ¾œ¿<br />

¸ »¤¼<br />

¾"# Ö+×<br />

ú%$'&(‡À<br />

¢ Ñ ¸ »¤¼<br />

Ë ¾2Ì ¸ Ë ¾ ¹ á! ý ¹<br />

Ñ ¸ »¤¼ Û<br />

Ë ¼<br />

¹<br />

¾<br />

corresponding to a constant time, can be easily evalu-<br />

©<br />

ated as the half-ellipsoid of revolution with center at ¸ ¦ ¼¥¤ ¼¤Š¾<br />

and semi-axes<br />

(A-8)<br />

* ¿ ê<br />

In symbols, we have the isochron<br />

ç ð Þ<br />

¨ ¿ ©<br />

¨ ¼<br />

and + ¿-, *<br />

(A-9)<br />

Ñ ¸ »¤¼<br />

µ À<br />

The Beylkin determinant (A-4), in this case, reduces to (see Martins et al., 1997)<br />

¨ Ñ<br />

» <br />

» <br />

(A-10)<br />

43 µ<br />

§ µ<br />

10<br />

ç¥é<br />

with<br />

óžô<br />

óžõ65<br />

and<br />

(A-11)<br />

¿87 ¸ »<br />

§ Ñ<br />

¿87 ¸ »<br />

§ Ñ<br />

À »5¾<br />

À »5¾<br />

ó÷õ<br />

ó÷ô<br />

Note that we do not need to íNî³ïð ò compute , since it will be canceled in the computation<br />

of the kernel (A-3). The last quantity we need íNî³ïbðñ is , which is given by<br />

ð Þ<br />

¿ µ<br />

§ ¸<br />

(A-12)<br />

¸ Ë ¾¾<br />

Therefore, the expression for the kernel (A-3) is<br />

ê Ç <br />

ð Þ<br />

íNî³ï ð ñ<br />

¸ »¤¼ Ë ¼à’¾S¿ ¨ µ<br />

» <br />

» <br />

(A-13)<br />

§ ¸<br />

¸ Ë ¾¾<br />

;:<br />

ê Ç <br />

óžõ<br />

We also must compute the gradiente ý Û Ñ<br />

. After some algebraic manipulation, we<br />

find<br />

à<br />

Ñ<br />

*@ À<br />

(A-14)<br />

ͳÿºÑ¿À<br />

¼<br />

and<br />

Í? Ñ¿<br />

where,<br />

ç¡ð<br />

(A-15)<br />

¾ ¸ *<br />

¾ §

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