J nieveen (6 risultati)

Condizione: New. ARRITMIAS CARDIACAS.

Paperback. Condizione: Good. 122 pages. ThesisThe contribution of refraction and absorption fluctuations to the measured scint illation were observed for a near-infrared absorption region using a NOAA design ed large aperture scintillometer. The logarithm amplitude spectra were shown to decay with a frequency as f sup-8/3/SUPfor both the absorption and scattering me chanism. For the absorption mechanism this is in line with similar observations made at microwave and infrared frequencies. However, for finite transmitting and receiving apertures, theory predicts a stronger decay of the scattering mechani sm due to aperture averaging. The spectral shape is characterised by a region of low frequency absorption, higher frequency refraction separated by a flattish t ransition zone. The upper observed corner frequency ( f C2 ), compared well with the calculated values using the measured transverse wind speed ( v ) for a know n aperture radius. The lower corner frequency ( f C1 ) position was shown to be sensitive to the ratio of the real and imaginary part of the refractive index st ructure parameter, ( C nRsup2/SUP/C nIsup2 /SUP) sup3/8/SUPand v . The part of t he spectrum associated with the absorption scintillations was observed to be muc h less than that due to refraction until the evening when decreasing C nRsup2 /S UPcaused C nRsup2/SUP/C nIsup2 /SUPto decrease and absorption to become signific ant. If absorption is ignored, this may have consequences for calculating noctur nal surface heat flux densities. During unstable, daytime conditions the large a perture scintillometer is most sensitive to refractive scintillations despite ha ving an infrared source transmitting in a lossy atmosphere. But also under these conditions, the low frequency absorption part of the spectrum is observable.…

Condizione: New.

Condizione: New.

Condizione: As New. Unread book in perfect condition.

Condizione: As New. Unread book in perfect condition.