Littérature scientifique sur le sujet « Minor atmospheric components »
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Articles de revues sur le sujet "Minor atmospheric components"
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Damiani, A., M. Storini, M. Laurenza et C. Rafanelli. « Solar particle effects on minor components of the Polar atmosphere ». Annales Geophysicae 26, no 2 (26 février 2008) : 361–70. http://dx.doi.org/10.5194/angeo-26-361-2008.
Texte intégralRésumé :
Abstract. Solar activity can influence the Earth's environment, and in particular the ozone layer, by direct modulation of the e.m. radiation or through variability of the incoming cosmic ray flux (solar and galactic particles). In particular, solar energetic particles (SEPs) provide additional external energy to the terrestrial environment; they are able to interact with the minor constituents of the atmospheric layer and produce ionizations, dissociations, dissociative ionizations and excitations. This paper highlights the SEP effects on the chemistry of the upper atmosphere by analysing some SEP events recorded during 2005 in the descending phase of the current solar cycle. It is shown that these events can lead to short- (hours) and medium- (days) term ozone variations through catalytic cycles (e.g. HOx and NOx increases). We focus attention on the relationship between ozone and OH data (retrieved from MLS EOS AURA) for four SEP events: 17 and 20 January, 15 May and 8 September. We confirm that SEP effects are different on the night and day hemispheres at high latitudes.
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Larin, I. K., et M. L. Kuskov. « Daytime and nighttime lifetimes of minor atmospheric components in the troposphere ». Russian Journal of Physical Chemistry B 8, no 2 (mars 2014) : 254–60. http://dx.doi.org/10.1134/s199079311402016x.
Texte intégral
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Anacleto, J. F., R. K. Boyd, S. Pleasance, M. A. Quilliam, J. B. Howard, A. L. Lafleur et Y. Makarovsky. « Analysis of minor constituents in fullerene soots by LC–MS using a heated pneumatic nebulizer interface with atmospheric pressure chemical ionization ». Canadian Journal of Chemistry 70, no 10 (1 octobre 1992) : 2558–68. http://dx.doi.org/10.1139/v92-325.
Texte intégralRésumé :
The minor constituents of toluene extracts of three fullerene-rich materials have been characterized by on-line LC–MS techniques, incorporating both positive and negative ion mass spectra obtained by atmospheric pressure chemical ionization. Two of the materials were soots, produced by resistive heating of graphite in an inert atmosphere, from different commercial suppliers. The third material was obtained as a condensate from a controlled laminar flame, and was shown previously (Anacleto etal:, Rapid Commun. Mass Spectrom. 6, 214 (1992)) to contain significant quantities of compounds that behaved under the present LC–MS conditions as isomers of the C60 and C70 fullerenes, and which reverted to the latter upon heating. This finding was confirmed here, and extended to the higher clusters C76, C84, C90, and C94. One of the graphite-derived soots contained monoxides of the carbon clusters as the principal minor components, while the other soot contained hydrogenated species including C60H2, C60H4, C70H2, and (C60•CH4). The flame-generated material contained all of these minor constituents, together with complexes of C60 with larger aliphatic molecules as well as large quantities of polycyclic aromatic hydrocarbons and related species. Photo-oxidation of a purified C60 preparation, from the graphitic soot containing mostly monoxide impurities, was shown to lead to increased levels of the mono-, di-, and tri-oxides of C60.
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Perrino, Cinzia, Maria Catrambone et Silvia Canepari. « Chemical Composition of PM10 in 16 Urban, Industrial and Background Sites in Italy ». Atmosphere 11, no 5 (8 mai 2020) : 479. http://dx.doi.org/10.3390/atmos11050479.
Texte intégralRésumé :
Italy is characterized by a very variable configuration in terms of altitude, proximity to the sea, latitude and the presence of industrial plants. This paper summarizes the chemical characterization of PM10 obtained from 38 sampling campaigns carried out in 16 sites in Italy during the years 2008–2018. Chemical determinations include all macro-components (six macro-elements, eight ions, elemental carbon and organic carbon). The sum of the individual components agrees well with the PM10 mass. The chemical composition of the atmospheric aerosol clearly reflects the variety in the Italian territory and the pronounced seasonal variations in the meteoclimatic conditions that characterize the country. Macro-sources reconstruction allowed us to identify and evaluate the strength of the main PM10 sources in different areas. On 10 sampling sites, the soluble and insoluble fractions of 23 minor and trace elements were also determined. Principal Component Analysis was applied to these data to highlight the relationship between the elemental composition of PM10 and the characteristics of the sampling sites.
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Sen Gupta, Alexander, et Matthew H. England. « Coupled Ocean–Atmosphere–Ice Response to Variations in the Southern Annular Mode ». Journal of Climate 19, no 18 (15 septembre 2006) : 4457–86. http://dx.doi.org/10.1175/jcli3843.1.
Texte intégralRésumé :
Abstract The coupled ocean–atmosphere–ice response to variations in the Southern Annular Mode (SAM) is examined in the National Center for Atmospheric Research (NCAR) Community Coupled Climate Model (version 2). The model shows considerable skill in capturing the predominantly zonally symmetric SAM while regional deviations between model and observation SAM winds go a long way in explaining the generally small differences between simulated and observed SAM responses in the ocean and sea ice systems. Vacillations in the position and strength of the circumpolar winds and the ensuing variations in advection of heat and moisture result in a dynamic and thermodynamic forcing of the ocean and sea ice. Both meridional and zonal components of ocean circulation are modified through Ekman transport, which in turn leads to anomalous surface convergences and divergences that strongly affect the meridional overturning circulation and potentially the pathways of intermediate water ventilation. A heat budget analysis demonstrates a conspiring of oceanic meridional heat advection, surface heat fluxes, and changes in mixed layer depth, which acts in phase to imprint a strong circumpolar SAM signature onto sea surface temperatures (SSTs), while other oceanic processes, including vertical advection, are shown to play only a minor role in contrast to previous suggestions. Lagged correlations show that although the SAM is mainly controlled by internal atmospheric mechanisms, the thermal inertia of the ocean reimprints the SAM signature back onto surface air temperatures (SATs) on time scales longer than the initial atmospheric signal. Sea ice variability is well explained by a combination of atmospheric and oceanic dynamic and thermodynamic forcing, and by an albedo feedback mechanism that allows ice extent anomalies to persist for many months. Nonzonally symmetric components of the SAM winds, particularly in the region surrounding the Antarctic Peninsula, have important effects for other climate variables.
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Taketani, F., Y. Kanaya, P. Pochanart, Y. Liu, J. Li, K. Okuzawa, K. Kawamura, Z. Wang et H. Akimoto. « Measurement of overall uptake coefficients for HO<sub>2</sub> ; radicals by aerosol particles sampled from ambient air at Mts. Tai and Mang (China) ». Atmospheric Chemistry and Physics 12, no 24 (17 décembre 2012) : 11907–16. http://dx.doi.org/10.5194/acp-12-11907-2012.
Texte intégralRésumé :
Abstract. HO2 uptake coefficients for ambient aerosol particles, collected on quartz fiber filter using a high-volume air sampler in China, were measured using an aerosol flow tube coupled with a chemical conversion/laser-induced fluorescence technique at 760 Torr and 298 K, with a relative humidity of 75%. Aerosol particles were regenerated with an atomizer using the water extracts from the aerosol particles. Over 10 samples, the measured HO2 uptake coefficients for the aerosol particles at the Mt. Tai site were ranged from 0.13 to 0.34, while those at the Mt. Mang site were in the range of 0.09–0.40. These values are generally larger than those previously reported for single-component particles, suggesting that reactions with the minor components such as metal ions and organics in the particle could contribute to the HO2 uptake. A box model calculation suggested that the heterogeneous loss of HO2 by ambient particles could significantly affect atmospheric HOx concentrations and chemistry.
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Docherty, K. S., A. C. Aiken, J. A. Huffman, I. M. Ulbrich, P. F. DeCarlo, D. Sueper, D. R. Worsnop et al. « The 2005 Study of Organic Aerosols at Riverside (SOAR-1) : instrumental intercomparisons and fine particle composition ». Atmospheric Chemistry and Physics 11, no 23 (12 décembre 2011) : 12387–420. http://dx.doi.org/10.5194/acp-11-12387-2011.
Texte intégralRésumé :
Abstract. Multiple state-of-the-art instruments sampled ambient aerosol in Riverside, California during the 2005 Study of Organic Aerosols at Riverside (SOAR) to investigate the chemical composition and potential sources of fine particles (PMf) in the inland region of Southern California. In this paper, we briefly summarize the spatial, meteorological and gas-phase conditions during SOAR-1 (15 July–15 August), provide detailed intercomparisons of high-resolution aerosol mass spectrometer (HR-AMS) measurements against complementary measurements, and report the average composition of PMf including the composition of the organic fraction measured by the HR-AMS. Daily meteorology and gas-phase species concentrations were highly consistent, displaying clear diurnal cycles and weekday/weekend contrast. HR-AMS measurements of non-refractory submicron (NR-PM1) mass are consistent and highly correlated with those from a filter dynamics measurement system tapered-element oscillating microbalance (TEOM), while the correlation between HR-AMS and heated TEOM measurements is lower due to loss of high volatility species including ammonium nitrate from the heated TEOM. Speciated HR-AMS measurements are also consistent with complementary measurements as well as with measurements from a collocated compact AMS while HR-AMS OC is similar to standard semi-continuous Sunset measurements within the combined uncertainties of both instruments. A correction intended to account for the loss of semi-volatile OC from the Sunset, however, yields measurements ~30% higher than either HR-AMS or standard Sunset measurements. On average, organic aerosol (OA) was the single largest component of PMf. OA composition was investigated using both elemental analysis and positive matrix factorization (PMF) of HR-AMS OA spectra. Oxygen is the main heteroatom during SOAR-1, with O/C exhibiting a diurnal minimum of 0.28 during the morning rush hour and maximum of 0.42 during the afternoon. O/C is broadly anti-correlated with H/C, while N/C and S/C (excluding organonitrate (ON) and organosulfate (OS) functionalities) are far lower than O/C at about 0.015 and ~0.001, respectively. When ON and OS estimates are included O/C, N/C, and S/C increase by factors of 1.21, 2, and 30, respectively, while H/C changes are insignificant. The increase in these ratios implies that ON accounts for ~1/2 of the organic nitrogen while OS dominate organic sulfur at this location. Accounting for the estimated ON and OS also improves the agreement between anions and cations measured by HR-AMS by ~8%, while amines have only a very small impact (1%) on this balance. Finally, a number of primary and secondary OA components were resolved by PMF. Among these a hydrocarbon-like OA and two minor, local OA components, one of which was associated with amines, were attributed to primary emissions and contributed a minor fraction (~20%) of OA mass. The remaining OA mass was attributed to a number of secondary oxidized OA (OOA) components including the previously-identified low-volatility and semi-volatile OOA components. In addition, we also report for the first time the presence of two additional OOA components.
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Proutsos, Nikolaos D., Aristotle Liakatas, Stavros G. Alexandris, Ioannis X. Tsiros, Dimitris Tigkas et George Halivopoulos. « Atmospheric Factors Affecting Global Solar and Photosynthetically Active Radiation Relationship in a Mediterranean Forest Site ». Atmosphere 13, no 8 (31 juillet 2022) : 1207. http://dx.doi.org/10.3390/atmos13081207.
Texte intégralRésumé :
Light availability and its composition in components affecting plant growth as photosynthetically active radiation (PAR), are of critical importance in agricultural and environmental research. In this work, radiation data for the period 2009–2014 in a forest site in Greece were analyzed to identify the effect of meteorological variables on the formation of the photosynthetically active to global solar radiation ratio. The temporal changes of the ratio are also discussed. Results showed that the ratio values are higher in summer (0.462) and lower in autumn (0.432), resulting in an annual average of 0.446. In addition, for the investigated site, which was characterized by relatively high water content in the atmosphere, the atmospheric water content and clearness were found to be the most influential factors in the composition of the global solar radiation in the wavelengths of PAR. On the contrary, temperature and related meteorological attributes (including relative humidity, vapor pressure deficit and saturation vapor pressure) were found to have minor effect.
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Zvyagintsev, A. M., G. Kakadzhanova et O. A. Tarasova. « Influence of air mass transport directions on the seasonal variations of concentrations of minor gas atmospheric components in Europe ». Russian Meteorology and Hydrology 35, no 7 (juillet 2010) : 441–48. http://dx.doi.org/10.3103/s1068373910070022.
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Heidari, Mohammad Reza, Zhaoyang Song, Enrico Degregori, Jörg Behrens et Hendryk Bockelmann. « Concurrent calculation of radiative transfer in the atmospheric simulation in ECHAM-6.3.05p2 ». Geoscientific Model Development 14, no 12 (6 décembre 2021) : 7439–57. http://dx.doi.org/10.5194/gmd-14-7439-2021.
Texte intégralRésumé :
Abstract. The scalability of the atmospheric model ECHAM6 at low resolution, as used in palaeoclimate simulations, suffers from the limited number of grid points. As a consequence, the potential of current high-performance computing architectures cannot be used at full scale for such experiments, particularly within the available domain decomposition approach. Radiation calculations are a relatively expensive part of the atmospheric simulations, taking up to approximately 50 % or more of the total runtime. This current level of cost is achieved by calculating the radiative transfer only once in every 2 h of simulation. In response, we propose extending the available concurrency within the model further by running the radiation component in parallel with other atmospheric processes to improve scalability and performance. This paper introduces the concurrent radiation scheme in ECHAM6 and presents a thorough analysis of its impact on the performance of the model. It also evaluates the scientific results from such simulations. Our experiments show that ECHAM6 can achieve a speedup of over 1.9× using the concurrent radiation scheme. By performing a suite of stand-alone atmospheric experiments, we evaluate the influence of the concurrent radiation scheme on the scientific results. The simulated mean climate and internal climate variability by the concurrent radiation generally agree well with the classical radiation scheme, with minor improvements in the mean atmospheric circulation in the Southern Hemisphere and the atmospheric teleconnection to the Southern Annular Mode. This empirical study serves as a successful example that can stimulate research on other concurrent components in atmospheric modelling whenever scalability becomes challenging.
Thèses sur le sujet "Minor atmospheric components"
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Damiani, A. « EFFECTS OF ENERGETIC SOLAR PARTICLES ON OZONE AND MINOR ATMOSPHERIC COMPONENTS INSIDE THE POLAR REGIONS ». Thesis, 2007. http://hdl.handle.net/2122/4165.
Texte intégralRésumé :
Solar activity influences the Earth’s environment, in particular the atmospheric
ozone, by the direct output of the e.m. radiation or through the variability of the
incoming cosmic ray flux (solar and galactic particles). Especially energetic particles,
arising from huge explosions on the Sun’s surface, travel in the interplanetary
medium and, if the circumstances were favorable, they could enter the terrestrial
atmosphere (driven by the geomagnetic field lines of our planet) and reach the polar
cap regions (geomagnetic latitude > 60°). There, they provide additional external
energy and are able to produce ionizations, dissociations, dissociative ionizations
and excitations phenomena by interacting with the minor constituents. The induced
changes are not confined to the ion chemistry but also to the neutral components. In
this way a rise of the concentration of HOx and NOx species and the triggering of
catalytic cycles which lead to short (hours) and medium (days) term ozone
destruction occur. Finally, also no-reactive reservoir species (e.g., HNO3, HCl, HOCl)
are involved in these processes and endure large variations.
The present thesis highlights the chemical variability of the middle atmosphere
during and after some Solar Energetic Particle (SEP) events recorded during the
current solar cycle. Special attention has been paid to the relationship between
ozone and HOx data (retrieved from the Microwave Limb Sounder of EOS AURA
satellite) for four events referred to 2005. The HOx data, recorded for the first time
during the intense ionization caused by the SEP flux, have pointed out some features
related to these phenomena not wholly captured by the current theoretical models. In
addition, they have highlighted that the HOx rise is able to destroy the so-called third
ozone peak at the polar latitudes of the winter hemisphere and it occurs also during
medium intensity events. Besides, the analyses of January 2005 SEP events have
shown that the changes on the hydrogen species leaded to variability in the
concentration and partitioning of chlorine family, not discernible in the summer
hemisphere. Further, the use of data coming from the HALOE instrument, referred to
SEP events occurred in July 2000 and April 2002, has in short confirmed past
experimental results. Finally, the study of a little SEP event occurred during May 2003
has pointed out that SEP events are not the unique ionization source inside the polar
latitudes during the winter.INAF-IFSI, CNR-ICES
Published
1.7. Osservazioni di alta e media atmosfera
open
Livres sur le sujet "Minor atmospheric components"
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Trieloff, Mario. Noble Gases. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190647926.013.30.
Texte intégralRésumé :
This is an advance summary of a forthcoming article in the Oxford Encyclopedia of Planetary Science. Please check back later for the full article.Although the second most abundant element in the cosmos is helium, noble gases are also called rare gases. The reason is that they are not abundant on terrestrial planets like our Earth, which is characterized by orders of magnitude depletion of—particularly light—noble gases when compared to the cosmic element abundance pattern. Indeed, such geochemical depletion and enrichment processes make noble gases so versatile concerning planetary formation and evolution: When our solar system formed, the first small grains started to adsorb small amounts of noble gases from the protosolar nebula, resulting in depletion of light He and Ne when compared to heavy noble gases Ar, Kr, and Xe: the so-called planetary type abundance pattern. Subsequent flash heating of the first small mm to cm-sized objects (chondrules and calcium, aluminum rich inclusions) resulted in further depletion, as well as heating—and occasionally differentiation—on small planetesimals, which were precursors of larger planets and which we still find in the asteroid belt today from where we get rocky fragments in form of meteorites. In most primitive meteorites, we even can find tiny rare grains that are older than our solar system and condensed billions of years ago in circumstellar atmospheres of, for example, red giant stars. These grains are characterized by nucleosynthetic anomalies and particularly identified by noble gases, for example, so-called s-process xenon.While planetesimals acquired a depleted noble gas component strongly fractionated in favor of heavy noble gases, the sun and also gas giants like Jupiter attracted a much larger amount of gas from the protosolar nebula by gravitational capture. This resulted in a cosmic or “solar type” abundance pattern, containing the full complement of light noble gases. Contrary to Jupiter or the sun, terrestrial planets accreted from planetesimals with only minor contributions from the protosolar nebula, which explains their high degree of depletion and basically “planetary” elemental abundance pattern. Indeed this depletion enables another tool to be applied in noble gas geo- and cosmochemistry: ingrowth of radiogenic nuclides. Due to heavy depletion of primordial nuclides like 36Ar and 130Xe, radiogenic ingrowth of 40Ar by 40K decay, 129Xe by 129I decay, or fission Xe from 238U or 244Pu decay are precisely measurable, and allow insight in the chronology of fractionation of lithophile parent nuclides and atmophile noble gas daughters, mainly caused by mantle degassing and formation of the atmosphere.Already the dominance of 40Ar in the terrestrial atmosphere allowed C. F v. Weizsäcker to conclude that most of the terrestrial atmosphere originated by degassing of the solid Earth, which is an ongoing process today at mid ocean ridges, where primordial helium leaves the lithosphere for the first time. Mantle degassing was much more massive in the past; in fact, most of the terrestrial atmosphere formed during the first 100 million years of Earth´s history, and was completed at about the same time when the terrestrial core formed and accretion was terminated by a giant impact that also formed our moon. However, before that time, somehow also tiny amounts of solar noble gases managed to find their way into the mantle, presumably by solar wind irradiation of small planetesimals or dust accreting to Earth. While the moon-forming impact likely dissipated the primordial atmosphere, today´s atmosphere originated by mantle degassing and a late veneer with asteroidal and possibly cometary contributions. As other atmophile elements behave similar to noble gases, they also trace the origin of major volatiles on Earth, for example, water, nitrogen, sulfur, and carbon.
Actes de conférences sur le sujet "Minor atmospheric components"
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Rob, Mohammad A., et Frank C. Franceschetti. « Atmospheric Multi-Component Pollution Analysis Using CO2 Laser ». Dans Laser Applications to Chemical Analysis. Washington, D.C. : Optica Publishing Group, 1992. http://dx.doi.org/10.1364/laca.1992.wc7.
Texte intégralRésumé :
The laser spectroscopic techniques for detecting minor gaseous pollutants of the atmosphere have made rapid advances in the last few years. The most important optical process for detection of air pollutants is based on the extinction of radiation by molecular absorption. Each molecule absorbs light at a particular wavelength or a range of wavelengths, a characteristic of the molecule. Thus a measurement of absorption of light at the molecule's characteristic wavelength produces a mean of determining a particular molecule at the presence of other molecules. Problems can, and often arise from overlapping spectrums due to other molecules of the atmosphere. In this case, it is necessary to identify the molecules which cause these overlappings. In some cases, one might be interested in finding multiple pollutants of the atmosphere.
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De Vos, Yves, Jean-Paul Janssens, Leo van Kooten et Jörg Alexnat. « PED Certified Recuperator for Micro Gas Turbines ». Dans ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3466.
Texte intégralRésumé :
The design and certification of a high performance recuperator for micro gas turbines is presented. The component has been developed and built for a 100kWel micro gas turbine. The recuperator heated up compressed air at 3.5 bar with exhaust gas near atmospheric pressure and recuperates 300 kWth at an effectiveness of 90%. This concept can readily be adapted for other micro gas turbines due to its modular design. The certification has been realized under Pressure Equipment Directive 97/23/EC, equivalent to ASME Boiler and Pressure Vessel Code, covering closed pressurized devices. However, minor leakage in the recuperator is allowed, thus requiring an inventive design and validation approach for meeting the certification requirements. This leak is caused by weld porosity: the heat exchanging core plates are laser welded, having over 1200 meters of sealing weld length in a single recuperator. The maximum allowable leak amounts to 3 10−6 mm2 per meter weld length. The maximum leak was 0.2% of the massflow on the pressurized side at the nominal operating point, and therefore did not adversely affect the effectiveness of the recuperator. The finite element calculations and the resulting design loops on components and weld connections are presented. Validation of the entire component is done under the Experimental Design Method. A hydrostatic pressure test at 8.4 bar and ambient temperature is executed in the presence of a certified notified body to demonstrate that the welds are sufficiently robust. This pressure is higher than the operating pressure to simulate the effect of temperature on the steel properties. A laser scanner is used to map the deformation of the unit under pressure and subsequently referenced to its original state. The maximum deviation measured is equal to 0.26 mm for the pressurized part, which is acceptable considering the size of the unit is 1000mm × 600mm × 1000mm. The strain levels went back to the values before putting the unit under pressure, indicating there are no residual deformations. The test is further accompanied with leakage rate measurements before and after the hydrostatic pressure test. If the difference between these leakages rates is within limits, the recuperator will pass the test. The measured total leakage area is 0.4 mm2, well below the maximum allowable value, and equivalent to 0.01% of the massflow at the nominal operating point. This means the recuperator passed the test successfully. Furthermore, a burst test was executed to determine the safety factor and to identify the weakest element of the design. The burst pressure is observed at 18.3 bar, resulting in a safety margin of 218% and 523% in reference to the PED and operational design pressures, respectively. The component responsible for failure has been further optimized for the next generation of recuperators. Field data confirm that the lifetime of the high performance recuperator meets the requirements of 40.000 h operating time. Additionally, the traceability of the serial produced components is handled by the audited quality management system. It covers the used materials, including lot traceability, the measured process characteristics and welder certifications. The approach can also be used for ASME certification.
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Grohmann, Jasper, Wolfgang Meier et Manfred Aigner. « Gas Turbine Model Combustor Emissions of Liquid Single-Component Fuels ». Dans ASME Turbo Expo 2017 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63182.
Texte intégralRésumé :
Alternative liquid fuels can contain hydrocarbons of different types and chain lengths and the fuel composition has an influence on combustion behavior. In this study, the influence of liquid single-component fuels on exhaust gas emissions of a gas turbine model combustor for swirl-stabilized spray flames was investigated under atmospheric pressure. The nozzle exhibited a dual-swirl geometry and a prefilming airblast atomizer. The spray was characterized by Phase Doppler Anemometry (PDA) and Mie scattering measurements and the flame CH* chemiluminescence was measured. Six single-component hydrocarbons were chosen: three linear alkanes (n-hexane, n-nonane, n-dodecane), one cyclic alkane (cyclohexane), one branched alkane (iso-octane) and one aromatic hydrocarbon (toluene). Kerosene Jet A-1 was used as a technical reference. Results show minor differences in CO emissions and significant differences in NOx emissions of the various fuels at comparable flow conditions and adiabatic flame temperatures. The measurements indicate a correlation between the nitric oxide emissions and the spray quality.
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Nickel, Hubertus, Willem J. Quadakkers et Lorenz Singheiser. « Determination of Corrosion Layers and Protective Coatings on Steels and Alloys Used in Simulated Service Environment of Modern Power Plants ». Dans ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-2249.
Texte intégralRésumé :
The development of modern power generation systems with higher thermal efficiency requires the use of constructional materials of higher strength and improved resistance to the aggressive service atmospheres. In this paper the following examples are discussed: 1) The oxidation behavior of 9% Cr steels in simulated combustion gases: The effects of O2 and H2O content on the oxidation behavior of 9% Cr steels in the temperature range 600–800°C showed that in dry oxygen a protective scale was formed with an oxidation rate controlled by diffusion. In contrast, that in the presence of water vapor, after an incubation period, the scale became non-protective as a result of a change in the oxidation mechanism. 2) The development of NiCrAlY alloys for corrosion resistant coatings and thermal barrier coatings of gas turbine components: The increase of component surface temperature in modern gas turbines leads to an enhanced oxidation attack of the blade coating. Considerable efforts have been made in the improvement of the temperature properties of MCrAlY coatings by the additions of minor elements like yttrium, silicon and titanium. The experimental results show the positive, but different influence of the oxidation behavior of the MCrAlY coatings by the addition of these minor elements. 3) The development of light-weight intermetallics of TiAl-basis: TiAl-based intermetallics are promising materials for future turbine components because of the combination of high temperature strength and low density. These alloys, however, possess poor oxidation resistance at temperatures above 700°C. The experimental results showed that the oxidation behavior of TiAl-based intermetallics can be strongly improved by minor additions of 1–2 at.-% silver. 4) The oxide dispersion strengthened (ODS) alloys provide excellent creep resistance up to much higher temperatures than can be achieved with conventional wrought or cast alloys in combination with suitable high temperature oxidation/corrosion resistance. The growth mechanisms of protective chromia and alumina scales were examined by a two-stage oxidation method with 18O tracer. The distribution of the oxygen isotopes in the oxide scale was determined by SIMS and SNMS. The results show the positive influence of a Y2O3 dispersion on the oxidation resistance of the ODS alloys and its effect on growth mechanisms.
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Tiwari, Pankaj Kumar, Debasis Priyadarshan Das, Parimal Arjun Patil, Prasanna Chidambaram, Zoann Low, Ahmad Ismail Azahree, M. Rashad Amir Rashidi et al. « Monitoring, Measurement and Verification MMV : A Critical Component in Making the CO2 Sequestration Success ». Dans International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21213-ms.
Texte intégralRésumé :
Abstract The increasing atmospheric concentration of carbon dioxide (CO2), a greenhouse gas (GHG) is creating environmental imbalance and affecting the climate adversely due to growing industrialization. Global leaders are emphasizing on controlling the production of GHG. However, growing demands of natural gas, industry is embarking on the development of high CO2 contaminant gas fields to meet supply gap. Development and management of contaminated hydrocarbon gas fields add additional dimension of sequestration of CO2 after production and separation in project management. CO2 sequestration is a process for eternity with a possibility of zero-degree failure. Monitoring, measuring and verification (MMV) of injected CO2 volume in sequestration is critical component along with geological site selection, transportation, storage process. The present study discusses all the impacting parameters which makes whole process environment friendly, economically prudent and adhering to national and international regulations. The migration of injected CO2 plume in the reservoir is uncertain and its monitoring is equally challenging. The role of MMV planning is critical in development of high CO2 contaminant fields of offshore Sarawak. It substantiates that injected CO2 in the reservoir is intact and safely stored for hundreds of years after injection and possesses minimum to no risk to HS&E. The deployment of Multi-Fiber Optic Sensor System (M-FOSS) promises a cost-effective solution for monitoring the lateral & vertical migration of CO2 plume by acquiring 4D DAS-VSP (Distributed Acoustic Sensor – Vertical Seismic Profile) survey and for the well integrity by analyzing DAS/DTS (Distributed Temperature Sensor)/DPS (Distributed Pressure Sensor)/DSS (Distributed Strain Sensor) data. Simulation results and injectivity test at laboratory for in-situ CO2 injection has demonstrated the possibility of over 100MMscfd/well injection in aquifer to meet the total CO2 injection of 1.2Bscfd for full field development while maintaining the reservoir integrity. Uncertainty & risk analysis shows possible presence of seismically undistinguished fractures and minor faults, an early breakthrough of injected CO2 cannot be ruled out. The depleted reservoir storage study divulges the containment capacity of identified carbonate reservoirs as well as conformance of potential storage sites. The fault-seal analysis and reservoir integrity studies determine the robustness of the long-term security of the CO2 storage. Injectivity study demonstrates the optimum and maximum possible rates of CO2 injection into these depleted gas reservoirs. VSP simulation results show that a subsurface coverage of 3-4 km2 per well is achievable, which along with simulated CO2 plume extent help to determine the number of wells required to get maximum monitoring coverage for the MMV planning. The deployment of M-FOSS technology is novel and proactive approach to monitor the CO2 plume migration and well integrity. First ever development of MMV Planning for CO2 Sequestration in offshore Sarawak, Malaysia using novel and cutting-edge M-FOSS technology for proactive monitoring of CO2 plume migration and well integrity.
Rapports d'organisations sur le sujet "Minor atmospheric components"
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Jurkevitch, Edouard, Carol Lauzon, Boaz Yuval et Susan MacCombs. role of nitrogen-fixing bacteria in survival and reproductive success of Ceratitis capitata, the Mediterranean fruit fly. United States Department of Agriculture, septembre 2005. http://dx.doi.org/10.32747/2005.7695863.bard.
Texte intégralRésumé :
Objectives: to demonstrate nitrogen fixation in the gut of Ceratitiscapitata, the Mediterranean fruit fly and that fixed nitrogen is important for the fly. Background: Fruit flies (Diptera: Tephritidae) are a highly successful, widespread group of insects causing enormous economic damage in agriculture. They are anautogenous, i.e. the acquisition of nitrogenous compounds by both male and female is essential for the realization of their reproductive potential. Nitrogen, although abundant in the atmosphere, is paradoxically a limiting resource for multicellular organisms. In the Animalia, biological nitrogen fixation has solely been demonstrated in termites. Major achievements and conclusions: We found that all individuals of field-collected medflies harbor large diazotrophicenterobacterial populations that express dinitrogenreductase in the gut. Moreover, nitrogen fixation was demonstrated in isolated guts and in live flies and may significantly contribute to the fly’s nitrogen intake. Specific components of these communities were shown to be transmitted vertically between flies. Moreover, we found that the gut bacterial community changes during the fly’s active season both in composition and complexity. Moreover, strong changes in community structure were also observed between the fly's various developmental stages. An initial analysis using SuPERPCR, a technology enabling the detection of minor populations by selective elimination of the dominant 16S rDNA sequences revealed that Pseudomonasspp. may also be part of the gut community. Implications: The presence of similar bacterial consortia in additional insect orders suggests that nitrogen fixation occurs in vast pools of terrestrial insects. On such a large scale, this phenomenon may have a considerable impact on the nitrogen cycle.