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FDTD 可以用来创建mpeg

This a program solves Maxwell Equations for arbitrary geometries
of objects with different conductivity and permitivity using the
 FDTD algorithm. Only first oder absorbing boundary conditions are
  applied. It is possible to create mpeg-movies.

Installation
============

The graphical output is done with matlab. Therefore you have to 
set some directories in the Makefile that matlab can find its 
libraries. This Makefile is set to work on the eecis.udel.edu
workstations.
Then add the matlab library path (on eecis.udel.edu:
/usr/local/matlab/extern/lib/sol2) to the LD_LIBRARY_PATH
enviroment variable. If the variable is not set at all just add

setenv LD_LIBRARY_PATH /usr/local/matlab/extern/lib/sol2

in your .cshrc file

After setting the directories call 'make'.

Run the program
===============

fdtd inputfile

Inputfile
=========

In this file you have to define the geometry, the voltage source
 and the different outputs. The file 'RLC' is an example of a 
 RLC-circuit. All values are in SI.

RLC:
------------------------------------------------------------------

// example of RLC circuit
// L and R comes from wires

dx 0.2e-6
time 1e-6
Nx 50
Ny 55
Nz 25

matlaboutput

//   x1 x2 y1 y2 z1 z2 sig r_eps
box  10 40 10 14 10 14 1e6  1
box  10 40 40 44 10 14 1e6  1

box  10 14 10 23 10 14 1e6  1
box  10 14 31 44 10 14 1e6  1

box  36 40 10 21 10 14 1e6  1
box  36 40 33 44 10 14 1e6  1

box  34 42 22 24 10 14 1e6  1
box  34 42 30 32 10 14 1e6  1


//      x1 x2 y1 y2 z1 z2 V D ramp   stay   Ri
voltage 12 12 24 30 12 12 1 y 1e-15 1e-11  1e-4

show_V  38 38 12 42 12 12  30
show_Component  Ey  z 12   30
show_J z 12 30

//movie 2 -2e5 15e5 1  Movie.mpg l
------------------------------------------------------------------

// denotes a comment line

The following items are necessary:
----------------------------------
	dx 0.2e-6

sets the space discretization to 0.2 micron.

	time 1e-6
	
sets the endtime of the calculation. You can also stop the program
 with ctrl-c.

	Nx 50
	Ny 55
	Nz 25

sets the number of gridpoints in each direction.

Other options
-------------

	matlaboutput

switches on the matlab output otherwice no output

	box  10 40 10 14 10 14 1e6  1
	
defines a rectangular box (x=10..40,y=10..14,z=10..14) of 
conductivity 1e6 and relativ permitivity 1.

	cone z 0 45    40 20  50 50  4e7   1

defines a cylinder or cone as follows:
z is the axis and the object goes from z=0 to z=45. The radiuses 
are 40 at z=0 and 20 at z=45. The axis lies at x=50 and y=50. 
Object has conductivity 4e7 and relativ permitivity of 1.
	
Boxes and Cones are read in the order of appearance. So its 
possible to overwrite data.

	voltage 12 12 24 30 12 12 1 y 1e-15 1e-11  1e-4

This describes a voltage source. The source is applied at x=12..12,
 y=24..30, z=12..12. Please make sure that the coordinates only 
 vary in one variable (same as direction). The value of the voltage
  is 1 and it works in y direction. 1e-15 is the time to get to 
  the full value (ramp). After 1e-15+1e-11 the source switches 
  back to 0. The inner resistivity is 1e-4.

	R 10 10 15 20 66 66  50 y
	
Lumped resistor: x=10..10,y=15..20,z=66..66, Resistivity=50, 
direction y.
Also make sure that the coordinates only vary in the 'direction'
 direction.

	C 10 10 15 20 66 66  50 y
	
Lumped capacitance: x=10..10,y=15..20,z=66..66, capacity=50, 
direction y.
Also make sure that the coordinates only vary in the 'direction'
 direction.


Output
------

	show_J z 30   10

Shows the current density J in the z=30 plane every 10 timesteps.

	show_D y 30   10

Shows the displacement current D in the y=30 plane every 10 
timesteps.

	show_Component Ey  x 10  30

Shows y-component of electrical field in the x=10 plane every 30
 timesteps.
Other possibilities: Ex Ey Ez Hx Hy Hz

	show_Emag z 30  10
	
Shows magnitude of electrical field (log10 plot).

	show_Hmag z 30  10
	
Shows magnitude of magnetic field (log10 plot).

	show_Vplane  z 12   y 7 42  0 49   50

Shows voltage in the z=12 plane, the voltage is calculated between
 y=7 and y=42 while x goes from 0 to 49. every 50 timesteps.

	show_V 10 13 19 30 10 40  30

Shows development of the voltage between the points (10,19,10) and
 (13,0,40) after every 30 timesteps.

Movies
------

you can create mpg-movies out of the different outputs. You have 
to fix the colormap for the movies. otherwice it would change 
automatically.
Therefore you have to run the program first without creating the
 movie and estimate the range of values.

Then you write for instance

	movie 2 -3e5 3e5 100 l
	
This creates a movie from the second output (order from inputfile).
 the colormap is fixed to values between -3e5 and 3e5 and the movie
  contains 100 pictures. l means that the quality is low but its 
  faster and the movie doesn't take to much space on disk. if you 
  choose h ist takes up to 20 or more minutes but the quality is 
  much higher.