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NMPB-Industry 2008

Lateral Diffraction

Three options for lateral diffraction are available for selection:

  • none: No lateral diffraction considered.
  • Point Sources: Lateral diffraction is considered at point sources, but not at line and area sources.

if Distance smaller (m)

This setting defines the distance between source and receiver for which lateral diffraction is taken into account. The default value is 1000 m.

Obstacles within Area Sources do not shield

When this option is active, any obstacle (e.g. buildings, foliage, barriers etc.) located within area sources (including parking lots and optimizable sources) provide no screening for any sub-source of that area source.

Example

see Concawe

Sources in Building/Cylinder do not shield

By default, a screening effect results for sources inside buildings and cylinders as the outer walls act as barriers.

For further details and an example see Concawe.

Temperature / rel. Humidity

The air attenuation is calculated based on the temperature and relative humidity. Intermediate frequency values result from linear interpolation. The temperature specified serves also as the ambient temperature when calculating the exhaust stack’s directivity.

Meteorology

Via the button „Meteorology“ the percentage of „favorable conditions“ in wind sectors stepped by 20° can be specified for the time periods D/E/N separately (for the time being, for Finland or France). The percentage refers to the assessment interval, usually an entire year.

List Box / Locations

For calculations using NMPB 2008 the following items from the list box apply:

  • (default): favorable conditions D/E/N = 50/75/100%
  • (favorable): favorable conditions D/E/N = 100/100/100%
  • (homogène): favorable conditions D/E/N = 0/0/0%
  • XXX (2) and XXX (3) with „XXX“ representing a French town and region: data of the percentage of favorable conditions for two (2: D, N) or three time periods (3: D, E, N) according to NMPB 2008.

For further details see NMPB-Routes 2008.

Use reference DLL

This option is deactivated by default. In this case, CadnaA code is used for the calculation implemented based on the printed documentation of NMPB 2008.

By activating this option the later released, but officially provided reference DLL (developed by the French consortium) is used for the calculation.

This option requires to copy the reference DLL (PropagationNMPB.dll) into the respective CadnaA installation directory. The DLL is not part of the CadnaA installation procedure and is, therefore, distributed separately.