scholarly journals First “in situ” determination of gas transport coefficients ( DO2, DAr, and DN2) from bulk gas concentration measurements (O2, N2, Ar) in natural sea ice

2014 ◽  
Vol 119 (10) ◽  
pp. 6655-6668 ◽  
Author(s):  
Odile Crabeck ◽  
B. Delille ◽  
S. Rysgaard ◽  
D. N. Thomas ◽  
N.-X. Geilfus ◽  
...  
Keyword(s):  
Sea Ice ◽  
Gas Transport ◽  
Transport Coefficients ◽  
Gas Concentration ◽  
Concentration Measurements

Quantitative determination of tip undercooling of faceted sea ice with in situ experiments

2021 ◽  
Author(s):  
Tongxin Zhang ◽  
Zhijun Wang ◽  
Lilin Wang ◽  
Junjie Li ◽  
Jincheng Wang
Keyword(s):  
Sea Ice ◽  
Quantitative Determination ◽  
In Situ Experiments

Determination of gas transport coefficients in ceramic bodies during thermolysis of organic additives

1996 ◽  
Vol 41 (3) ◽  
pp. 116-128 ◽  
Author(s):  
J. H. Song ◽  
J. R. G. Evans ◽  
M. J. Edirisinghe ◽  
E. H. Twizell
Keyword(s):  
Gas Transport ◽  
Transport Coefficients ◽  
Organic Additives

scholarly journals Eddy-covariance flux errors due to biases in gas concentration measurements: origins, quantification and correction

2014 ◽  
Vol 11 (4) ◽  
pp. 1037-1051 ◽  
Author(s):  
G. Fratini ◽  
D. K. McDermitt ◽  
D. Papale
Keyword(s):  
Eddy Covariance ◽  
Calibration Data ◽  
Correction Procedure ◽  
Gas Concentration ◽  
Turbulent Fluctuations ◽  
Laboratory Calibration ◽  
Concentration Measurements ◽  
Main Determinants ◽  
Long Timescales

Abstract. Errors in gas concentration measurements by infrared gas analysers can occur during eddy-covariance campaigns, associated with actual or apparent instrumental drifts or biases due to thermal expansion, dirt contamination, aging of components or errors in field operations. If occurring on long timescales (hours to days), these errors are normally ignored during flux computation, under the assumption that errors in mean gas concentrations do not affect the estimation of turbulent fluctuations and, hence, of covariances. By analysing instrument theory of operation, and using numerical simulations and field data, we show that this is not the case for instruments with curvilinear calibrations; we further show that if not appropriately accounted for, concentration biases can lead to roughly proportional systematic flux errors, where the fractional errors in fluxes are about 30–40% the fractional errors in concentrations. We quantify these errors and characterize their dependency on main determinants. We then propose a correction procedure that largely – potentially completely – eliminates these errors. The correction, to be applied during flux computation, is based on knowledge of instrument calibration curves and on field or laboratory calibration data. Finally, we demonstrate the occurrence of such errors and validate the correction procedure by means of a field experiment, and accordingly provide recommendations for in situ operations.

Determination of Gas Transport Coefficients of Mixed Gases in 6FDA-TMPDA Polyimide by NMR Spectroscopy

2017 ◽  
Vol 50 (9) ◽  
pp. 3590-3597 ◽  
Author(s):  
Leoncio Garrido ◽  
Carolina García ◽  
Mar López-González ◽  
Bibiana Comesaña-Gándara ◽  
Ángel E. Lozano ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Gas Transport ◽  
Transport Coefficients ◽  
Mixed Gases

scholarly journals Eddy-covariance flux errors due to biases in gas concentration measurements: origins, quantification and correction

2013 ◽  
Vol 10 (8) ◽  
pp. 13679-13717 ◽  
Author(s):  
G. Fratini ◽  
D. K. McDermitt ◽  
D. Papale
Keyword(s):  
Eddy Covariance ◽  
Calibration Data ◽  
Correction Procedure ◽  
Gas Concentration ◽  
Turbulent Fluctuations ◽  
Laboratory Calibration ◽  
Long Time ◽  
Concentration Measurements ◽  
Main Determinants

Abstract. Errors in gas concentration measurements by infrared gas analysers can occur during eddy-covariance campaigns, associated with actual or apparent instrumental drifts or to biases due to thermal expansion, dirt contamination, aging of components or errors in field operations. If occurring on long time scales (hours to days), these errors are normally ignored during flux computation, under the assumption that errors in mean gas concentrations do not affect the estimation of turbulent fluctuations and, hence, of covariances. By analysing instrument theory of operation, and using numerical simulations and field data, we show that this is not the case for instruments with curvilinear calibrations; we further show that if not appropriately accounted for, concentration biases can lead to roughly proportional systematic flux errors, where the fractional errors in fluxes are about 30–40% the fractional errors in concentrations. We quantify these errors and characterize their dependency on main determinants. We then propose a correction procedure that largely – potentially completely – eliminates these errors. The correction, to be applied during flux computation, is based on knowledge of instrument calibration curves and on field or laboratory calibration data. Finally, we demonstrate the occurrence of such errors and validate the correction procedure by means of a field experiment, and accordingly provide recommendations for in situ operations. The correction described in this paper will soon be available in the EddyPro software (www.licor.com/eddypro).

In situ determination of creep properties of sea ice with the pressuremeter

1989 ◽  
Vol 26 (4) ◽  
pp. 575-594 ◽  
Author(s):  
J. R. Murat ◽  
B. Ladanyi ◽  
P. Huneault
Keyword(s):  
Sea Ice ◽  
Data Acquisition System ◽  
Data Interpretation ◽  
Stress Redistribution ◽  
In Situ Testing ◽  
Creep Properties ◽  
New Procedures ◽  
Proper Consideration

A series of pressuremeter creep and relaxation tests was carried out in the spring of 1987 in a sea-ice cover at Igloolik, Northwest Territories, for the purpose of testing some new procedures for in situ determination of creep properties of sea ice. Compared with a similar field study carried out 9 years earlier, the present investigation included some clear improvements, not only in the instrumentation and data acquisition system but also in the data interpretation and processing. In particular, it is shown that consistent values of creep parameters can be obtained only if proper consideration is made of the amount of stress redistribution taking place before and during each new load application. Key words: in situ testing, pressuremeter, sea ice, creep properties, stress redistribution.

INDIREKTE PAPIERCHROMATOGRAPHISCHE METHODE ZUR BESTIMMUNG DER HARNOESTROGENE

1961 ◽  
Vol 38 (4) ◽  
pp. 545-562 ◽  
Author(s):  
L. Kecskés ◽  
F. Mutschler ◽  
I. Glós ◽  
E. Thán ◽  
I. Farkas ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Granulosa Cell ◽  
Iron Content ◽  
List Type ◽  
Granulosa Cell Tumour ◽  
Hydrolysis Of ◽  
Phenol Fraction ◽  
Qualitative Determination

ABSTRACT 1. An indirect paperchromatographic method is described for separating urinary oestrogens; this consists of the following steps: acidic hydrolysis, extraction with ether, dissociation of phenol-fractions with partition between the solvents. Previous purification of phenol fraction with the aid of paperchromatography. The elution of oestrogen containing fractions is followed by acetylation. Oestrogen acetate is isolated by re-chromatography. The chromatogram was developed after hydrolysis of the oestrogens 'in situ' on the paper. The quantity of oestrogens was determined indirectly, by means of an iron-reaction, after the elution of the iron content of the oestrogen spot, which was developed by the Jellinek-reaction. 2. The method described above is satisfactory for determining urinary oestrogen, 17β-oestradiol and oestriol, but could include 16-epioestriol and other oestrogenic metabolites. 3. The sensitivity of the method is 1.3–1.6 μg/24 hours. 4. The quantitative and qualitative determination of urinary oestrogens with the above mentioned method was performed in 50 pregnant and 9 non pregnant women, and also in 2 patients with granulosa cell tumour.

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