Re: [femm] Re: various

["Bruce McGee" <mcgee@xxxxxxxxxxxxxxxxxx>]

Recommend that you stay with peak quantities since it follows naturally from
the quasi-steady state formulation of Maxwell's equations.


----- Original Message -----
From: <dcm3c@xxxxxxx>
To: <femm@xxxxxxxxxxx>
Sent: Monday, May 22, 2000 8:01 AM
Subject: [femm] Re: various


> In a message dated 5/18/00 5:34:54 AM Eastern Daylight Time,
> rlbrambilla@xxxxxxx writes:
>
> > These are my suggestions that, I hope, require simple modifications.
> >
> > GLOBAL : a command for a custom dafault settings (units, materials
etc.).
> > Actually I use a template file.
>
> Including some sort of standard (but user-modifiable) template would be a
> good idea.
>
> > GEOMETRY : commands for inserting points and lines by keyboard. In
large
> > packages there are tens of this commands, most of them never used. Only
two
> > commands are strictly enough (but unavoidable) for the model precision
:
> > Point(x,y), and Line(x1,y1,x2,y2).
>
> You can do this already. In pretty much any situation where a specific
point
> needs to be specified, you can hit the <tab> key. A dialog will pop up,
> allowing you to enter the coordinates of a point by keyboard, rather than
> having to use the mouse.
>
> > RESULTS : similar Point and Line keyboard commands to read results and
to
> > paste values to the clip-board for exporting. Actually it is possible
to
> > paste only the field picture, but I need to export values to other
programs
> > for successive elaborations.
> > Fine will be to have command to select the quantity I want the contour
> > lines (as in actual xy-plot).
>
> You can get the data from an xy plot to disk by checking the "write data
to
> text file" check box in the dialog where you select what sort of xy plot
is
> to be created. Having an option to send it to the clipboard might be a
good
> idea as well.
>
> > And now a little remark.
> > In frequency dependent problems, inserting point currents,
> > I insert peak value, i.e. Io for a varying current Io exp(jwt).
> > Reading the results for a selected point I find Bx, By, |B|.
> > I suppose again Bx exp(jwt), By exp(jwt).
> > Now your |B|=sqrt(|Bx|^2+|By|^2) and the time factor is cancelled
> > by conjugation. So it may be considered an "istantaneous constant
modulus".
> > Usually we need the time averaged over a period so this value
> > has to be divided by sqrt(2). To avoid this external operation
> > I insert Ieff=Io/sqrt(2) as a point current. But in this case
> > I cannot suppose Ieff exp(jwt)! So it seems to me that the output
> > <|B|> = |B|/sqrt(2) and peak value insertion would be more clear.
>
> In an attempt to be consistent and make things flow sort of "naturally"
from
> the magnetostatic to harmonic cases, I have kept all results in terms of
> amplitudes, rather than RMS quantities. I might see about putting in a
> choice of "modes" for the output results, either the complex amplitudes
(as
> it does now), amplitude and phase angle, or RMS quantities.
>
> > Hoping for future improvements,
> > sincerly yours Roberto
>
> Thanks for your comments.
>
> -----------------------------------------
>
> In a message dated 5/18/00 8:16:04 AM Eastern Daylight Time,
> eckart.nipp@xxxxxxxx writes:
>
> > A difficulty is the rectangular selection tool. With that it is
comparably
> > troublesome to select e.g. a rotor of an asynchronous motor with all
its
> > slots but not any part of the stator. This is particularly hard if the
> > airgap is short. Maybe an optional circular selection tool can be
> > developed. Also a deselection possibility, e.g. by holding shift, would
be
> > useful. When playing around with a not predefined geometry also the
> > possibility of moving parts per mouse may be useful.
>
> Different selection tools might be useful. With the way that the
selection
> tool currently works, you can use it multiple times to select all the
parts
> of a geometry that has a more complicated shape--the previously selected
> stuff doesn't automatically get deselected.
>
> Anyhow, a good way to analyze a rotor at different positions in the 3.0
> version is to assign all of the parts of the rotor to one "Group" as you
> build it. Then, you can select the entire rotor with just one right-click
of
> the mouse when the editor is in "group" mode.
>
> > Can the circuit property also be used to define the voltage of an
exciter
> > coil which is aymmetrically placed so that it is unknown in the
beginning
> > how the total voltage distributes on forward and backward pathes?
>
> There's a feature that's sort of "hidden" having to do with circuit
results.
> In the postprocessor, choose the View | Circuit Props selection off of the
> main menu. This allows you to see what voltage was required to impose a
> prescribed current, or how much current was obtained from an applied
voltage
> for a particular circuit (as appropriate). This might allow you to get
the
> information that you are after.
>
> > Now I think I also found a bug in the group copy tool. When I chose a
> > circle consiting of two 180deg arcs and copy it as a row, i.e. several
> > copies at once, I get the desired circles but in addition a row of
anchor
> > points.
>
> I've been able to duplicate this bug--many thanks for catching it. This
was
> the sort of thing that I was hoping to have people find with this beta
> version....
>
> > Greetings
> > Eckart
>
> Dave.
> --
> http://members.aol.com/dcm3c
>
>
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