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Wind Speed

MikeArmstrong
12-Amethyst

Wind Speed

Hi

I have attached a calc for the design of wind speed in accordance with BS 6933.

I have having trouble writing a program which will automatically select the corresponding letter from data3.

The letter choice is dependent of distance from the sea and effective height. I have written a program which selects the correct column depending on the distance from the sea but cannot seem to incorporate the effective height to yield the correct letter.

Any suggestions welcome.


Regards

Mike
12 REPLIES 12

You had some Given block dozen pages down the work sheet ??? I have tried to make the jjj(INPUT,DATA) work, but it won't for "input:=2", disabling the scripted component. Can't understand the error message.

jmG

You need a bit more clarity and consistency with your input tables.
__________________
� � � � Tom Gutman

Thanks for the comments guys.

Sorry about the confusion with the tables, I have now changes them to excel components which are easier to understand.

The data has been duplicated due to the two cases (town/country) as you stated Tom. The data is correct which has been taken straight from the standard.

You are correct when you have taken the upper values as the reference values are ranges.

Regards

Mike

Tom

Would you be able to suggest a program similar to the one which you suggested for the category letter program?

Again interpolation is required for the effective height and distance from sea.

The program which I have written selects the correct date for the values in the table but doesn�t interpolate between them.


Regards

Mike

YOu can do a 2D interpolation as was done for the augmentation data. But I would suggest extremem circumspection in using this. You just don't have a lot of data points. It's hard to know what is a reasonable interpolation when you have values at just 0, 2 and 100. That's a big between.

Also, the range and spread of the C values is such that I would usually try to do a log transformation. But that is not possible here, as you start with a zero value. There may be other transformations that make for a more reasonable function. But even with such, your data is very sparse.
__________________
� � � � Tom Gutman

The beauty of cubic splines is that the time consuming operation of finding the coefficients can be done once for the data set, and evaluating the spline for any particular value is then a fairly fast operation. A scheme that redoes the coefficient calculations for each value desired tends to be a bit slow for any significant use.

m/hr is a rather unusual velocity unit. What are you measuring -- snails?
__________________
� � � � Tom Gutman

I am using the units of m/sec

Regards

Mike

Yes, that is a normal unit. But the pcture from VFO is showing a unit of m/hr. Unusual. That entire post was directed at VFO and the picture he posted, nothing to do with any of your sheets.
__________________
� � � � Tom Gutman

Ok cheers for the help Tom.

The interpolation seems to be working exactly as i wanted.

Regards

Mike

On 7/20/2009 6:18:57 AM, Tom_Gutman wrote:
>That entire post was
>directed at VFO and the
>picture he posted, nothing to
>do with any of your sheets.
>__________________
>� � � � Tom Gutman
Why? You can study it!
And see the 3D-interpolation on MAS:
http://twtmas.mpei.ac.ru/mas/Worksheets/Interp_f_x_y.mcd


Val
http://twt.mpei.ac.ru/ochkov/v_ochkov.htm

>m/hr is a rather unusual velocity unit.
>What are you measuring -- snails?
It is a water velocity in the filter!
In my picture we have
Pressure drop:=f(velocity, temperature)

Try for example one WebSheet:
http://twt.mpei.ac.ru/MCS/Worksheets/Dow/DOWEX-MARATHON-A2/Fig-2.xmcd

Val
http://twt.mpei.ac.ru/ochkov/v_ochkov.htm
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