scholarly journals Real-time analysis of <i>δ</i><sup>13</sup>C- and <i>δ</i>D-CH<sub>4</sub> in ambient air with laser spectroscopy: method development and first intercomparison results

2016 ◽  
Vol 9 (1) ◽  
pp. 263-280 ◽  
Author(s):  
S. Eyer ◽  
B. Tuzson ◽  
M. E. Popa ◽  
C. van der Veen ◽  
T. Röckmann ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Real Time ◽  
Method Development ◽  
Isotope Analysis ◽  
Isotope Ratio Mass Spectrometry ◽  
Ambient Air ◽  
Repeated Measurements ◽  
Laser Absorption ◽  
Real Time Analysis

Abstract. In situ and simultaneous measurement of the three most abundant isotopologues of methane using mid-infrared laser absorption spectroscopy is demonstrated. A field-deployable, autonomous platform is realized by coupling a compact quantum cascade laser absorption spectrometer (QCLAS) to a preconcentration unit, called trace gas extractor (TREX). This unit enhances CH4 mole fractions by a factor of up to 500 above ambient levels and quantitatively separates interfering trace gases such as N2O and CO2. The analytical precision of the QCLAS isotope measurement on the preconcentrated (750 ppm, parts-per-million, µmole mole−1) methane is 0.1 and 0.5 ‰ for δ13C- and δD-CH4 at 10 min averaging time. Based on repeated measurements of compressed air during a 2-week intercomparison campaign, the repeatability of the TREX–QCLAS was determined to be 0.19 and 1.9 ‰ for δ13C and δD-CH4, respectively. In this intercomparison campaign the new in situ technique is compared to isotope-ratio mass spectrometry (IRMS) based on glass flask and bag sampling and real time CH4 isotope analysis by two commercially available laser spectrometers. Both laser-based analyzers were limited to methane mole fraction and δ13C-CH4 analysis, and only one of them, a cavity ring down spectrometer, was capable to deliver meaningful data for the isotopic composition. After correcting for scale offsets, the average difference between TREX–QCLAS data and bag/flask sampling–IRMS values are within the extended WMO compatibility goals of 0.2 and 5 ‰ for δ13C- and δD-CH4, respectively. This also displays the potential to improve the interlaboratory compatibility based on the analysis of a reference air sample with accurately determined isotopic composition.

scholarly journals Real-time analysis of δ<sup>13</sup>C- and δD-CH<sub>4</sub> in ambient air with laser spectroscopy: method development and first intercomparison results

2015 ◽  
Vol 8 (8) ◽  
pp. 8925-8970 ◽  
Author(s):  
S. Eyer ◽  
B. Tuzson ◽  
M. E. Popa ◽  
C. van der Veen ◽  
T. Röckmann ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Real Time ◽  
Method Development ◽  
Isotope Analysis ◽  
Isotope Ratio Mass Spectrometry ◽  
Ambient Air ◽  
Laser Absorption ◽  
Real Time Analysis ◽  
Averaging Time

Abstract. In situ and simultaneous measurement of the three most abundant isotopologues of methane using mid-infrared laser absorption spectroscopy is demonstrated. A field-deployable, autonomous platform is realized by coupling a compact quantum cascade laser absorption spectrometer (QCLAS) to a preconcentration unit, called TRace gas EXtractor (TREX). This unit enhances CH4 mole fractions by a factor of up to 500 above ambient levels and quantitatively separates interfering trace gases such as N2O and CO2. The analytical precision of the QCLAS isotope measurement on the preconcentrated (750 ppm, parts-per-million, μmole/mole) methane is 0.1 and 0.5 ‰ for δ13C- and δD-CH4 at 10 min averaging time. Based on replicate measurements of compressed air during a two-week intercomparison campaign, the repeatability of the TREX-QCLAS was determined to be 0.19 and 1.9 ‰ for δ13C and δD-CH4, respectively. In this intercomparison campaign the new in situ technique is compared to isotope-ratio mass-spectrometry (IRMS) based on glass flask and bag sampling and real time CH4 isotope analysis by two commercially available laser spectrometers. Both laser-based analyzers were limited to methane mole fraction and δ13C-CH4 analysis, and only one of them, a cavity ring down spectrometer, was capable to deliver meaningful data for the isotopic composition. After correcting for scale offsets, the average difference between TREX–QCLAS data and bag/flask sampling–IRMS values are within the extended WMO compatibility goals of 0.2 and 5 ‰ for δ13C- and δD-CH4, respectively. Thus, the intercomparison also reveals the need for reference air samples with accurately determined isotopic composition of CH4 to further improve the interlaboratory compatibility.

scholarly journals New on-line method for water isotope analysis of speleothem fluid inclusions using laser absorption spectroscopy (WS-CRDS)

2014 ◽  
Vol 10 (1) ◽  
pp. 429-467 ◽  
Author(s):  
S. Affolter ◽  
D. Fleitmann ◽  
M. Leuenberger
Keyword(s):  
Isotopic Composition ◽  
Fluid Inclusions ◽  
Isotope Analysis ◽  
Isotope Ratio Mass Spectrometry ◽  
Laser Absorption ◽  
On Line ◽  
Injection Unit ◽  
Water Measurement ◽  
Δd And Δ18o ◽  
Water Gas

Abstract. A new online method to analyse water isotopes of speleothem fluid inclusions using a wavelength scanned cavity ring down spectroscopy (WS-CRDS) instrument is presented. This novel technique allows us to simultaneously measure hydrogen and oxygen isotopes for a released aliquot of water. To do so, we designed a new simple line that allows the on-line water extraction and isotope analysis of speleothem samples. The specificity of the method lies in the fact that fluid inclusions release is made on a standard water background, which mainly improves the δD reliability. To saturate the line, a peristaltic pump continuously injects standard water into the line that is permanently heated to 140 °C and flushed with dry nitrogen gas. This permits instantaneous and complete vaporisation of the standard water resulting in an artificial water background with well-known δD and δ18O values. The speleothem sample is placed into a copper tube, attached to the line and after system stabilisation is crushed using a simple hydraulic device to liberate speleothem fluid inclusions water. The released water is carried by the nitrogen/standard water gas stream directly to a Picarro L1102-i for isotope determination. To test the accuracy and reproducibility of the line and to measure standard water during speleothem measurements a syringe injection unit was added to the line. Peak evaluation is done similarly as in gas chromatography to obtain δD and δ18O isotopic composition of measured water aliquots. Precision is better than 1.5‰ for δD and 0.4‰ for δ18O for water measurement for an extended range (−210 to 0‰ for δD and −27 to 0‰ for δ18O) primarily dependent on the amount of water released from speleothem fluid inclusions and secondarily on the isotopic composition of the sample. The results show that WS-CRDS technology is suitable for speleothem fluid inclusion measurements and gives results that are comparable to Isotope Ratio Mass Spectrometry (IRMS) technique.

Real-Time Analysis Of In-Situ Spectroscopic Ellipsometric Data During Mbe Growth Of III-V Semiconductors

1991 ◽  
Vol 222 ◽  
Author(s):  
B. Johs ◽  
J. L. Edwards ◽  
K. T. Shiralagi ◽  
R. Droopad ◽  
K. Y. Choi ◽  
...  
Keyword(s):  
Real Time ◽  
Optical Constants ◽  
Growth Parameters ◽  
Ex Situ ◽  
Time Analysis ◽  
Mbe Growth ◽  
In Situ Data ◽  
Real Time Analysis

ABSTRACTA modular spectroscopic ellipsometer, capable of both in-situ and ex-situ operation, has been used to measure important growth parameters of GaAs/AIGaAs structures. The ex-situ measurements provided layer thicknesses and compositions of the grown structures. In-situ ellipsometric measurements allowed the determination of growth rates, layer thicknesses, and high temperature optical constants. By performing a regression analysis of the in-situ data in real-time, the thickness and composition of an AIGaAs layer were extracted during the MBE growth of the structure.

scholarly journals In-situ observations of the isotopic composition of methane at the Cabauw tall tower site

2016 ◽  
Author(s):  
Thomas Röckmann ◽  
Simon Eyer ◽  
Carina van der Veen ◽  
Maria E. Popa ◽  
Béla Tuzson ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
High Precision ◽  
Temporal Resolution ◽  
Isotope Ratio ◽  
Mesoscale Model ◽  
Ambient Air ◽  
Model Calculations ◽  
Dual Isotope ◽  
Methane Budget

Abstract. High precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS) based technique for in-situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw experimental site for atmospheric research (CESAR) in the Netherlands and performed in-situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of +(0.05 ± 0.03) ‰ for δ13C and –(3.6 ± 0.4) ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high precision and temporal resolution dataset does not only reveal the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site, but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget, when they are performed at multiple sites that are representative for the entire European domain.

Assistive Systems for the Workplace

Gamification ◽  
2015 ◽  
pp. 1936-1949 ◽  
Author(s):  
Oliver Korn ◽  
Markus Funk ◽  
Albrecht Schmidt
Keyword(s):  
Computer Science ◽  
Real Time ◽  
Generic Model ◽  
Work Processes ◽  
Repetitive Work ◽  
Motion Recognition ◽  
Real Time Analysis ◽  
Work Routines ◽  
Assistive Systems

Recent advances in motion recognition allow the development of Context-Aware Assistive Systems (CAAS) for industrial workplaces that go far beyond the state of the art: they can capture a user's movement in real-time and provide adequate feedback. Thus, CAAS can address important questions, like Which part is assembled next? Where do I fasten it? Did an error occur? Did I process the part in time? These new CAAS can also make use of projectors to display the feedback within the corresponding area on the workspace (in-situ). Furthermore, the real-time analysis of work processes allows the implementation of motivating elements (gamification) into the repetitive work routines that are common in manual production. In this chapter, the authors first describe the relevant backgrounds from industry, computer science, and psychology. They then briefly introduce a precedent implementation of CAAS and its inherent problems. The authors then provide a generic model of CAAS and finally present a revised and improved implementation.

Evaluation of continuous δ13CH4 measurements in Heidelberg and at Schauinsland, Germany

2020 ◽  
Author(s):  
Antje Hoheisel ◽  
Frank Meinhardt ◽  
Martina Schmidt
Keyword(s):  
Isotopic Composition ◽  
Mole Fraction ◽  
Isotope Analysis ◽  
Ambient Air ◽  
Peak Height ◽  
West Germany ◽  
Livestock Farming ◽  
Biogenic Methane ◽  
The Mean ◽  
Instrumental Development

&lt;p&gt;Instrumental development in measurement technique now allows continuous in-situ isotope analysis of &lt;sup&gt;13&lt;/sup&gt;CH&lt;sub&gt;4&lt;/sub&gt; by Cavity Ring-Down Spectroscopy (CRDS). Analyses of the isotopic composition of methane in ambient air can potentially be used to partition between different CH&lt;sub&gt;4&lt;/sub&gt; source categories.&lt;/p&gt;&lt;p&gt;Since 2014 a CRDS G2201-i analyser has been used to continuously measure CH&lt;sub&gt;4&lt;/sub&gt; and its &lt;sup&gt;13&lt;/sup&gt;C/&lt;sup&gt;12&lt;/sup&gt;C ratio in ambient air at the Institute of Environmental Physics (IUP) in Heidelberg (116m a.s.l.), South-West Germany. Furthermore, the CRDS G2201-i analyser was installed twice for a month at the measurement station of the German Environment Agency at Schauinsland (1205m a.s.l.). In September 2018 and in February 2019 the analyser was moved to Schauinsland to examine the validity of evaluations of continuous &amp;#948;&lt;sup&gt;13&lt;/sup&gt;CH&lt;sub&gt;4 &lt;/sub&gt;measurements at a semi-rural station.&lt;/p&gt;&lt;p&gt;As an urban station, the seasonal and daily variations of the measured CH&lt;sub&gt;4&lt;/sub&gt; mole fraction and isotopic composition in Heidelberg vary much stronger than at the mountain station Schauinsland. The precision of the isotopic source signature calculation using a Keeling plot strongly depends on the CH&lt;sub&gt;4&lt;/sub&gt; peak height and instrumental precision. Therefore, at Schauinsland station the lower variability in the CH&lt;sub&gt;4&lt;/sub&gt; mole fraction makes the evaluation challenging. Different methods such as monthly/weekly interval evaluations and moving Keeling/Miller Tans methods has been used to calculate the isotopic source signature in ambient air.&lt;/p&gt;&lt;p&gt;The isotopic methane source signatures of the air in Heidelberg was found to be between -75 &amp;#8240; and -35 &amp;#8240;, with an average of (-54 &amp;#177; 2) &amp;#8240;. An annual cycle can be noticed with more depleted values (-56 &amp;#8240;) in summer and more enriched values (-51 &amp;#8240;) in winter, due to larger biogenic emissions in summer and more thermogenic (e.g. natural gas) emissions in winter. The mean isotopic source signature calculated at Schauinsland shows variations, too, with more enriched values (&amp;#8722;56 &amp;#8240;) in winter and more depleted (&amp;#8722;60 &amp;#8240;) ones in autumn. The more depleted values in summer/autumn at Schauinsland corresponds to more biogenic methane and can be explained by dairy cows grazing near the station especially during this time.&lt;/p&gt;&lt;p&gt;The generally more enriched values at Schauinsland are caused by the more rural surrounding. Emission estimates of county provided by the LUBW Landesanstalt f&amp;#252;r Umwelt Baden-W&amp;#252;rttemberg shows that around Schauinsland 60 % of the CH&lt;sub&gt;4&lt;/sub&gt; emissions are emitted by livestock farming and around Heidelberg only 28 %. The mean isotopic source signature calculated using these emissions is (-58 &amp;#177; 2) &amp;#8240; for Schauinsland and (-53 &amp;#177; 2) &amp;#8240; for Heidelberg. These results agreed well with the mean source signatures determined out of continuous isotopic measurements.&lt;/p&gt;

scholarly journals In-Situ and Real-Time Analysis of the Formation of Strains and Microstructure Defects during Solidification of Al-3.5 Wt Pct Ni Alloys

2008 ◽  
Vol 39 (4) ◽  
pp. 865-874 ◽  
Author(s):  
G. Reinhart ◽  
A. Buffet ◽  
H. Nguyen-Thi ◽  
B. Billia ◽  
H. Jung ◽  
...  
Keyword(s):  
Real Time ◽  
Time Analysis ◽  
Ni Alloys ◽  
Real Time Analysis

scholarly journals Measurement report: Methane (CH<sub>4</sub>) sources in Krakow, Poland: insights from isotope analysis

2021 ◽  
Author(s):  
Malika Menoud ◽  
Carina van der Veen ◽  
Jaroslaw Necki ◽  
Jakub Bartyzel ◽  
Barbara Szénási ◽  
...  
Keyword(s):  
Time Series ◽  
Isotopic Composition ◽  
Transport Model ◽  
Isotope Analysis ◽  
Ambient Air ◽  
Coal Extraction ◽  
Night Time ◽  
Isotopic Signatures ◽  
Ch4 Emissions ◽  
Gas Leaks

Abstract. Methane (CH4) emissions from human activities are a threat to the resilience of our current climate system, and to the adherence of the Paris Agreement goals. The stable isotopic composition of methane (δ13C and δ2H) allows to distinguish between the different CH4 origins. A significant part of the European CH4 emissions, 3.6 % in 2018, comes from coal extraction in Poland; the Upper Silesian Coal Basin (USCB) being the main hotspot. Measurements of CH4 mole fraction (χ(CH4)), δ13C and δ2H in CH4 in ambient air were performed continuously during 6 months in 2018 and 2019 at Krakow, Poland, 50 km east of the USCB. In addition, air samples were collected during parallel mobile campaigns, from multiple CH4 sources in the footprint area of the continuous measurements. The resulting isotopic signatures from sampled plumes allowed us to distinguish between natural gas leaks, coal mine fugitive emissions, landfill and sewage, and ruminants. The use of δ2H in CH4 is crucial to distinguish the fossil fuel emissions in the case of Krakow, because their relatively depleted δ13C values overlap with the ones of microbial sources. The observed χ(CH4) time series showed regular daily night-time accumulations, sometimes combined with irregular pollution events during the day. The isotopic signatures of each peak were obtained using the Keeling plot method, and generally fall in the range of thermogenic CH4 formation – with δ13C between −55.3 and −39.4 ‰ V-PDB, and δ2H between −285 and −124 ‰ V-SMOW. They compare well with the signatures measured for gas leaks in Krakow and USCB mines. The CHIMERE transport model was used to compute the CH4 and isotopic composition time series in Krakow, based on two emission inventories. The χ(CH4) are generally under-estimated in the model. The simulated isotopic source signatures, obtained with Keeling plots on each simulated peak using the EDGAR v5.0 inventory, indicate that a higher contribution from fuel combustion sources in EDGAR would lead to a better agreement. The isotopic mismatches between model and observations are mainly caused by uncertainties in the assigned isotopic signatures for each source category, and the way they are classified in the inventory. These uncertainties are larger for emissions close to the study site, which are more heterogenous than the ones advected from the USCB coal mines. Our isotope approach proves to be very sensitive in this region, thus helping to evaluate emission estimates.

A New Method To Interpret Fracturing Pressure—Application to Frac Pack

SPE Journal ◽  
2015 ◽  
Vol 20 (03) ◽  
pp. 508-517 ◽  
Author(s):  
Elias Pirayesh ◽  
Mohamed Y. Soliman ◽  
Mehdi Rafiee ◽  
Ali Jamali
Keyword(s):  
Real Time ◽  
New Technique ◽  
Logarithmic Scale ◽  
Analysis Tool ◽  
Real Time Analysis ◽  
Pressure Application ◽  
Invaluable Tool ◽  
Theory Application ◽  
Pressure Analysis

Summary Real-time analysis of fracturing data is an invaluable tool for determining whether a fracturing job is progressing as planned. Since early days, understanding of fracturing pressure was emphasized and practiced by the industry. The most well-known fracturing-pressure-analysis tool is the Nolte-Smith technique. To predict the geometry of a hydraulically induced fracture, the Nolte-Smith technique analyzes the pressure response of a formation during pumping. Extensive application of this technique has proved reliable to interpret fracturing events. However, the compression of data imposed by logarithmic scale may make the detection of some events difficult. In addition, the Nolte-Smith technique necessitates prior accurate knowledge of formation-closure pressure. In this paper, we present a real-time fracturing diagnostic. This method, which is based on a modification of the Nolte-Smith technique, has proved reliable in the interpretation of fracturing behavior while a fracturing job is being carried out. In addition, it eliminates the shortcomings of the original technique, meaning that while making the interpretation of fracturing pressure faster, the new technique does not require prior knowledge of formation in-situ stresses. This technique was reached by a new innovative moving-reference-point concept assembled with the power-law fracture-propagation theory. Application of the new technique in the analysis of a variety of field cases, including several frac-pack and regular fracturing treatments, proved successful.

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