Waves on the Internet

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GEOMETRICAL approaches


FAST MARCHING METHODS AND LEVEL SET METHODS
J.A. SETHIAN Dept. of Mathematics, Univ. of California, Berkeley, California 94720
http://www.math.berkeley.edu/~sethian/level_set.html

"Fast Marching Methods, introduced by Sethian (1996) and level set methods, introduced by Osher and Sethian (1988) are numerical techniques designed to track the evolution of interfaces.
Fast marching method: an interface separating regions moves with a speed given at the points of the interface. Calculation of the moving front. Arrival time surfaces: T(x,y)=const. Hamilton - Jacobi equation. Motion by/under curvature: velocity is proportional to the curvature. Numerical technique.

Level set equation: an additional dimension is involved, and the level sets of a partial differential equation /level set equation/ moves with the prescribed velocitty.

Books:
Level Set Methods - Evolving Interfaces in Geometry, Fluid Mechanics, Computer Vision, and Materials Science
J.A. Sethian, Cambridge University Press, 1996, 1999.
 

Huygens wavefront tracing:  A robust alternative to conventional ray tracing
Paul Sava and Sergey Fomel
http://sepwww.stanford.edu/oldsep/sergey/sepsergey/huygens/paper_html/
http://sepwww.stanford.edu/sep/paul/seg98/html/paper_html/node1.html
 

FERMAT

The Principle ofLeast Action

http://ourworld.compuserve.com/homepages/cuius/idle/evolution/ref/leastact.html
 
 
 

Stationary paths
http://www.mathpages.com/rr/s3-04/3-04.htm
 
 

Fermat's principle
http://www.treasure-troves.com/physics/FermatsPrinciple.html
/Minimum or stationarity. Saddle point./
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Fermat's principle, geometrical optics:
http://www.mobius.demon.co.uk/lasers/ferm.html

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Waves, elementary
http://id.mind.net/~zona/mstm/physics/waves/waves.html

Signals, wave, eikonal, not elementary
http://www22.pair.com/csdc/ed3/ed3fre24.htm

Solitons:
ANDREY MIROSHNICHENKO:
Sine-Gordon Solitons and Soliton Collisions
http://ece.wpi.edu/courses/ee535/hwk96/hwk5cd96/yinlu/sect3.html

Partial Differential Equations:
http://gamba.math.ubc.ca/coursedoc/math256/math/pde.html
Eric Brunet and Bernard Derridae: Shift in the velocity of a front due to a cut-off. Physical Review E 1997, 56 (3), 2597--2604
 

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