Applied Geophysics : Seismics

Free Motion of a Seismometer

Applet ( in separate window, ca. 440 x 410 Pixel )

The applet displays
  the displacement ( DSP_OUT )
  and / or
  the velocity ( VEL_OUT )
of the free motion of the moving mass of a seismometer
  for different damping values of the system
  and
  for different initial condiditions
  ( displacement X(+0) and velocity V(+0) ).

The time axes is normalized to
  T_0, the natural period of the ( undamped ) seismometer,
the velocity to
  the circular natural frequency W_0 ( = 2 × π / T_0 ).

( Background : see Seismometer Documentation )

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- HowTo -

Dialogue Window :
( Screenshot )

The Parameters of the output signals to be displayed are selected in the parameter dialogue ( background light blue ) :

> The damping of the seismometer is
>   selected from ALP= 0.2 ... ALP= 2.0
> or
>   adjusted ( ADJUST ) between 0.001 and 99.999
>   ( DEC / INC, in steps of 10.0 ... 0.001 ).

> The output signal of the seismometer is selected from SEISMO OUT :
>   DSP_OUT = displacement transducer
> or
>   VEL_OUT = velocity transducer.

> The initial displacement and velocity of the moving mass are selected from INITIAL CONDITIONS :
>   X(+0) = 1 / V(+0) = 0,
>   X(+0) = 0 / V(+0) = 1,
>   X(+0) = 1 / V(+0) = 1,
> or
>   X(+0) = 1 / V(+0) = -1.

> Comparison of output signals :

> With DAMPING = 0.2 ... 2.0, the output signals
>   of one type of output ( SEISMO OUT ) and
>   for one initial state ( INITIAL CONDITIONS )
> are displayed simultaniously
>   for five different values of seismometer damping,

> with SEISMO OUT = DSP+VEL, the signals
>   for one damping value ( DAMPING ) and
>   for one initial state ( INITIAL CONDITIONS )
> are displayed
>   for both displacement and velocity output,

> and with INITIAL CONDITIONS = X/V: 1/0+..., the signals
>   for one damping value ( DAMPING ) and
>   for one type of output ( SEISMO OUT )
> are displayed siultaneously
>   for four sets of initial conditions.

CLEAR TEXT ...
  clears the text area of the applet,
  lists the actually selected output signals in the range 0.00 ... 4.00 of normalized time ( LIST OUTP. ),
  and
  displays the time and velocity normalization ( DISP NORM. ).

PLOT
  shows / hides the graphic display of output signals.

INFO and HELP refer to the graphic display windows, where
  informations to the actual cursor position ( INFO )
and / or
  hints to actually possible mouse actions ( HELP )
are displayed.

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Graphic Display :
( Screenshot SEISMO OUT = DSP+VEL )

The time scale is normalized to
  the natural period T_0 of the ( undamped ) seismometer,
the velocity to
  the circular natural frequency W_0 = 2 × π / T_0
( see screenshot text area, below ).

( Background : see Seismometer Documentation )

Text Area :
( Screenshot DISP NORM. )

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Class and html files for a local installation of the applet are available as a zip file and as a tar.gz file.

More applets at : Geophysics Department TU Clausthal

Rev. 12-aug-2012

Comments to Fritz Keller
( ned gschempfd isch globd gnueg )

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