Analyse af solafskærmninger mht. termiske og ... - Viden om vinduer

ange if min 1 if 2
max 0
max ( )
min ( )
The fraction not covered is given by fra( ). This is the part to be included in the
extrapolation (fra( ) svarer til de skraverede områder på figur d.1.e.).
fra 1 range
Next we need to define the function that extrapolates the measured data. Any type of
function can be used, the only restriction is that it must be a function of only. Here we
give two examples.
When fitting the data in the Excel sheet containing the output of AXUM_NEW.exe, it
should be remembered that the values of the optical property at given , are expressed in
terms of units per sr, where is the solid angle defined by the resolution of the
detector head (half angle 0.5°). The solid angle is given by
2
0.5 deg
sin
0 deg
d 2.3924 10 4
Example of a linear extrapolation
As an example, we choose a linear extrapolation, starting at 1, where the value of the
optical property is R per sr, to 0, beyond which the value of the optical property is 0.
In finding the optimal straight line, 1 must be chosen so that there are enough data points
for 1 to get a good estimate of the best fit. As the extrapolation only covers values of
greater than min , setting 1 = min to obtain the best fit straight line through the data
for > min is probably the optimal choice. However, this is not essential, a value of 0 <
min can be chosen, as the equations given below allow for this.
In this example, for a scan with
25° to fit the line.
= = 25° (i.e. min = 25°), we used the data for
Input the extrapolation function and its parameters: (De indsatte værdier findes i filen
blisax.exl på den vedlagte cd-rom)
0 47.984deg R
F if 1 0 R 0
0 1 0
4.009510 5
27
1d
sr
1 25 deg R 0.1676
The estimated contribution from parts of the hemisphere not covered in the scan is Z