scholarly journals Dependence of mean spectral extinction coefficient of phytoplankton on depth, water color, and species

1980 ◽  
Vol 25 (1) ◽  
pp. 157-159 ◽  
Author(s):  
David Atlas ◽  
T. T. Bannister
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xinxin Zhang ◽  
Xiaoze Du

This paper engages in experimental measurements on thermal radiative transfer in silica aerogel and its composite insulation materials (xonotlite-aerogel composite and ceramic fibre-aerogel composite). The samples of silica aerogel, xonotlite-type calcium silicate, and ceramic fibre insulation materials are all considered as a semi-transparent medium capable of absorbing, emitting and scattering thermal radiation. The spectral transmittances are then measured at different infrared wavelengths ranging from 2.5 to 25μm with a Fourier transform infrared spectrometer (FTIR), and subsequently used to determine the specific spectral extinction coefficient and the specific Rossland mean extinction coefficient of the sample. The radiative conductivities deduced from the overall thermal conductivities measured with the transient hot-strip (THS) method are compared with the predictions from the diffusion approximation by using the measured spectral extinction coefficient. The results show that the spectral extinction coefficients of the samples are strongly dependent on the wavelength, particularly in the short wavelength regime (<10μm). The total Rossland mean extinction coefficients of the samples are all decreasing with the temperature increasing. The radiative conductivities are found almost proportional to the cubic temperature, and decreases as the sample density increases.


2016 ◽  
Vol 43 (2) ◽  
pp. 239-250
Author(s):  
Md Ashrafur Rahman ◽  
Sabira Sultana ◽  
Md Abdus Salam

Study was conducted to determine the physico-chemical parameters of water of three different lakes in Jahangirnagar University campus from March to November, 2013. The selected parameters were water depth, water temperature, conductivity, transparency, pH, dissolve O2, free CO2, total alkalinity, hardness, sulfate and water color. Water depth fluctuated from 140 cm to 385 cm, temperature ranged from 250C to 310C, conductivities ranged from 627 ?S/cm to 1544 ?S/cm, transparency from 22 cm to 87 cm, considerable variation of water colors were found and pH ranged from 6.4 to 7.5 without having any significant fluctuation. Dissolve oxygen (DO) ranged from 2.7 mg/l to 7.6 mg/l, carbon dioxide level ranged from 16 mg/l to 62 mg/l, total alkalinity and hardness were ranged from 43 mg/l to 92 mg/l and 63 mg/l to 134 mg/l, respectively with slight variations in different lakes in different months. During the study period, all the spots showed minimum fluctuation of physico-chemical parameters from the normal range without having some exceptions.Bangladesh J. Zool. 43(2): 239-250, 2015


1997 ◽  
Vol 15 (3) ◽  
pp. 180-202 ◽  
Author(s):  
Paolo Coppa ◽  
Antonio La Malfa

Visibility of escape routes is most important to guarantee the safety of people indoors during fires. In the case of a fire, visibility is strongly in fluenced by the smoke present in the room. In the present work, the extinction co efficient of the visible light has been experimentally measured in the presence of the smoke produced by four different test fires, named TF2, TF3, TF4, and TF5. Tests have been carried out in a specially suited test room in the Italian Fire De partment Research Center, provided with instruments to measure the optical density of smoke and the spectral extinction coefficient.


1982 ◽  
Vol 60 (11) ◽  
pp. 1641-1647
Author(s):  
A. W. Harrison ◽  
J. Lant

The horizon line softening method of determining the atmospheric spectral extinction coefficient σ(λ) is analyzed in detail indicating an inherent lower limit σ0(λ) on the range of σ(λ) which can be measured by this technique. As the observation height h above the earth surface increases, σ0(λ) decreases. A comparative experimental study of horizon line scanning telephotometry and contrast telephotometry is described, the results of which show the former technique to be useful under certain observing conditions.


Kerntechnik ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. 194-199
Author(s):  
H. Çam ◽  
A. Küçükönder ◽  
B. G. Durdu ◽  
M. Doğru ◽  
S. Karatepe

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