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Table 5: Table centre frequency / Octave filter
The centre frequency of the third-octave and the octave
is the square root resulting from the product of both limit
frequencies. The upper limit frequency of the octave is twice
the lower limit frequency, and the upper limit frequency of
the third-octave is 3 2 the lower limit frequency.
When there is talk of these filters, it is about filters of
constant, relative bandwidth. On a logarithmic frequency
Fig. 7:
Aerial photograph – Steel works Krupp Mannesmann HKM
Issue 04 | 2010
TRANSFER OF TECHNOLOGY
scale, there are the bandwidths always equidistant.
The bandwidths of the two filters, however, increase
logarithmically when getting plotted in linear frequency
scale. That is due to the descending energy content in
case of higher frequencies.
Description of a classic plant
The plant described here is part of a steeped in tradition,
very modern steel works with a stockyard for different
sorts of coal. The stockyard is served by a stacker and two
rail-bound scraper reclaimers. The coal mainly arrives on
barges at the port, situated at a distance of 1 km, where
unloading of the barges takes place by means of a grabtype
ship unloader. Through a pipe conveyor and other belt
conveyor systems, the coal is directly transported from the
port to the storage bins of the coking plant or the stockyard
for getting stored temporarily.
The steel works already exist since 100 years. In
the course of this century, the residential areas kept on
approaching the steel works. Structural alterations within
the steel works must always be aimed at reducing, as far
as possible, the annoyance of the residents caused by
immissions, but they must not bring about an increase of
the latter.
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