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[Feature Request] Using nomograms (graphical function definition)

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[Feature Request] Using nomograms (graphical function definition)

Sometimes I need to run a string of calculations on components that include factors that vary according to a manufacturer-supplied nomogram. For instance, acceptable shaft sideload on a gearbox may depend on where (exactly) the load is applied, or on how fast the gearbox is running. This information is often (almost always) supplied as a nomogram in the catalog.

For example: (From an Apex Dynamics catalog)

GearboxNomogram.png

It would be nice to be able to somehow recreate the nomogram in MathCAD and treat it as a function definition.

The family-of-curves aspect would be great, but just getting a single trace into the worksheet would be really good.

I envision it working like this:

Start by defining a function as a nomogram f(x):=<nomogram>

Optionally import a bitmap file (bmp, gif, png, jpg, etc) as an underlay

Register the coordinate axes to the underlaid image by dragging the axis origins and end points. (Note: the origin is NOT always zero!)

Scale the axes and define the type of gradations (linear, log). Match the axis scale to the image scale by dragging tickmarks and endpoints and entering values for what those tickmarks and endpoints represent.

Define one or more curves as a combination of straight-line and curve segments. Quadratic, cubic, and exponential curves would probably cover most of the required curves. Adding an arbitrary weighted spline would pretty much take care of everything else.

Use your new function as required!

I know that the accuracy of the function would be rough, but it would be better than hand-entering a point and forgetting to update as things change.

Or maybe this has already been done?

4 Comments
Opal

There are various options already out there to turn your graphs into data. Some are free ("Tracer" is one, but I'm not sure if you can still get it), some are not. If you have a frequent need for this, want a lot of flexibility (which it sounds like to do), and are willing to pay for that, try this: http://www.silkscientific.com/. I have an old version, and it works great. I assume the current version is even better.

Emerald III

I have created a lot of nomograns on Mathcad Server and can help you/

See one of them:

http://twt.mpei.ac.ru/MCS/Worksheets/RH/Eng-AMBERLITE-IRA402-Cl-co-courent-2.xmcd

You can find a lot of my Mathcad nomograms on the Knovel site - www.knovel.com

KnovelOchkov.png

Visitor

Those are impressive. It looks like you had to do some hand-digitizing to pull that off. That's the part I'd like to see some graphical tools help out with.

The other thing that I'd like is to be able to graphically reverse engineer function plots that are obviously built of several distinct segments. e.g.: y(x):=10 if x<5, 2x if 5 <= x < 10, etc.

I know these can be built up with programming, or with delta functions, but it hurts. Oh, it hurts.

Emerald III

See

William Wicker wrote:

The other thing that I'd like is to be able to graphically reverse engineer function plots that are obviously built of several distinct segments. e.g.: y(x):=10 if x<5, 2x if 5 <= x < 10, etc.

See one Mathcad Server calculation - the duration of periods with specific temperatures outside air during the heating period in some cities in Russia:

http://twt.mpei.ac.ru/MCS/Worksheets/Thermal/T-T-4-Tab-6-15.xmcd