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Artigos de revistas sobre o assunto "Mass absorption coefficients"
1
Buse, Ben, e Stuart Kearns. "Quantification of Olivine Using Fe Lα in Electron Probe Microanalysis (EPMA)". Microscopy and Microanalysis 24, n.º 1 (fevereiro de 2018): 1–7. http://dx.doi.org/10.1017/s1431927618000041.
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AbstractQuantification of first series transition metal Lα X-rays is hampered by absorption and in some cases transition probabilities (fluorescence yields) varying with chemical bonding. Compound mass absorption coefficients for Fe Lα were measured in the olivine solid solution series [Forsterite (Mg2SiO4) to Fayalite (Fe2SiO4)] and the mass absorption coefficients for Fe Lα absorbed by Fe were calculated. The mass absorption coefficients vary systematically between Fo83 and Fo0. Using the measured mass absorption coefficients for both standard and unknown and by correcting for a systematic discrepancy, consistent with varying partial fluorescence yields, a good agreement between calculated k-ratios and measured k-ratios is achieved. The systematic variations allow quantification of unknown k-ratios. The described method of quantification requires modification of matrix correction routines to allow standards and unknowns to have different mass absorption coefficients, and to incorporate solid solution mass absorption coefficients and partial fluorescence yield corrections derived from regression of experimental data.
2
Bairlein, Katharina, e Oliver Hupe. "INFLUENCE OF NEW MASS ENERGY-ABSORPTION COEFFICIENTS FROM ICRU REPORT NO. 90 ON AIR KERMA TO DOSE EQUIVALENT CONVERSION COEFFICIENTS". Radiation Protection Dosimetry 185, n.º 1 (6 de dezembro de 2018): 27–33. http://dx.doi.org/10.1093/rpd/ncy213.
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Abstract In Report No. 90 of the International Commission on Radiation Units and Measurements (ICRU), new mass energy-absorption coefficients are listed which are based on renormalized Scofield photoeffect cross-sections. The mass energy-absorption coefficients are the basis for the conversion coefficients from air kerma to the operational quantities listed in ISO 4037-3. Although ICRU does not give a recommendation if these new mass energy-absorption coefficients should be applied instead of the values used so far, an examination of the possible consequences for radiation protection quantities is necessary. We calculated the conversion coefficients for the X-ray qualities specified in ISO 4037-1 with the new mass energy-absorption coefficients and with the mass energy-absorption coefficients used so far to determine the deviations. Our calculations show that the change of the conversion coefficients due to the new values from ICRU Report No. 90 is negligible.
3
Hitzenberger, Regina. "Absorption and mass absorption coefficients measured with the integrating plate method". Journal of Aerosol Science 20, n.º 8 (janeiro de 1989): 1205–8. http://dx.doi.org/10.1016/0021-8502(89)90798-2.
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Rickerby, David G., e Norbert Wächter. "Effective L-Series Mass Absorption Coefficients for EDS". Microchimica Acta 132, n.º 2-4 (abril de 2000): 157–61. http://dx.doi.org/10.1007/s006040050057.
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Seltzer, Stephen M. "Calculation of Photon Mass Energy-Transfer and Mass Energy-Absorption Coefficients". Radiation Research 136, n.º 2 (novembro de 1993): 147. http://dx.doi.org/10.2307/3578607.
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Mahmoud Aboelkheir, Ibrahim Mohamed. "Trends in an Absorption Column through Mass Transfer Coefficients". Cognizance Journal of Multidisciplinary Studies 2, n.º 1 (30 de janeiro de 2022): 38–57. http://dx.doi.org/10.47760/cognizance.2022.v02i01.003.
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A study was conducted to measure the values of m.t.c and N of an absorption column. Values of N were in the range of 10-5, while those of m.t.c were in the range of 10-7. The trends with variables were confirmed with the previous studies. However, they were not with m.t.c. Pressure variance was suggested as the reason. Error was assessed at a percentage of 15% for m.t.c, and under 2% for pressure. Using other methods than only measuring concentration of solute with the Hempl apparatus was recommended.
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Babikian, D. S., D. K. Edwards, S. E. Karam, C. P. Wood e G. S. Samuelsen. "Experimental mass absorption coefficients of soot in spray combustorflames". Journal of Thermophysics and Heat Transfer 4, n.º 1 (janeiro de 1990): 8–15. http://dx.doi.org/10.2514/3.29157.
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Chipera, Steve J., e David L. Bish. "Measurement of Mass Absorption Coefficients Using Compton-Scattered Cu Radiation in X-ray Diffraction Analysis". Advances in X-ray Analysis 34 (1990): 325–35. http://dx.doi.org/10.1154/s0376030800014634.
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AbstractThe mass absorption coefficient is a useful parameter for quantitative characterization of materials. If the chemical composition of a sample is known, the mass absorption coefficient can be calculated directly. However, the mass absorption coefficient must be determined empirically if the chemical composition is unknown. Traditional methods for determining the mass absorption coefficient involve measuring the transmission of monochromatic X-rays through a sample of known thickness and density. Reynolds (1963,1967), however, proposed a method for determining the mass absorption coefficient by measuring the Compton or inelastic X-ray scattering from a sample using Mo radiation on an X-ray fluorescence spectrometer (XRF). With the recent advances in solid-state detectors/electronics for use with conventional powder diffractometers, it is now possible to readily determine mass absorption coefficients during routine X-ray diffraction (XRD) analyses.Using Cu Kα radiation and Reynolds’ method on a Siemens D-500 diffractometer fitted with a Kevex Si(Li) solid-state detector, we have measured the mass absorption coefficients of a suite of minerals and pure chemical compounds ranging in μ/ρ from graphite to Fe-metal (μ/ρ = 4.6-308 using Cu Kα radiation) to ±4.0% (lσ). The relationship between the known mass absorption coefficient and the inverse count rate is linear with a correlation coefficient of 0.997. Using mass absorption coefficients, phase abundances can be determined during quantitative XRD analysis without requiring the use of an internal standard, even when an amorphous component is present.
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Alkire, R. W. "Approximating the near-edge mass absorption coefficients for Ni using an ultra-thin bimetal foil". Journal of Applied Crystallography 50, n.º 1 (1 de fevereiro de 2017): 1–13. http://dx.doi.org/10.1107/s1600576716017544.
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In an effort to improve the characteristics of a fluorescing metal-foil-based beam position monitor, a new bimetal ultra-thin (0.98/0.67 µm) Ti–Ni foil was introduced to replace an existing single-element ultra-thin 0.5 µm thick Cr foil. During characterization it was determined that absorption measurements on the bimetal foil could be used to fit the Ni mass absorption coefficients accurately in the vicinity of the Ni K edge. Comparison with experimental results from the literature demonstrated that the fitting procedure produced coefficients with uncertainties of the order of ±1%. Once determined, these fit coefficients allowed the thickness of an independently mounted 8 µm thick Ni foil to be computed from absorption measurements instead of relying on a tool-based measurement of the foil thickness. Using the 8 µm thick foil, a continuous map of Ni mass absorption coefficients was produced at 1 eV resolution throughout the near-edge region. This high-resolution map marks a significant improvement over the existing NIST XCOM or FFAST database mass absorption coefficients, which have estimated errors of 10–20% for the near-edge region.
10
Gabitto, Jorge, e Costas Tsouris. "Determination of reactive mass transfer coefficients for CO2 absorption predictions". Separation Science and Technology 54, n.º 13 (13 de abril de 2019): 2026–33. http://dx.doi.org/10.1080/01496395.2019.1603240.
Texto completo da fonteTeses / dissertações sobre o assunto "Mass absorption coefficients"
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Miller, Jacob. "Modelling the Effect of Catalysis on Membrane Contactor Mass Transfer Coefficients for Carbon Dioxide Absorption Systems". University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627662756315225.
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Benmakhlouf, Hamza. "Key Data for the Reference and Relative Dosimetry of Radiotherapy and Diagnostic and Interventional Radiology Beams". Doctoral thesis, Stockholms universitet, Fysikum, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-114413.
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Accurate dosimetry is a fundamental requirement for the safe and efficient use of radiation in medical applications. International Codes of Practice, such as IAEA TRS-398 (2000) for radiotherapy beams and IAEA TRS-457 (2007) for diagnostic radiology beams, provide the necessary formulation for reference and relative dosimetry and the data required for their implementation. Research in recent years has highlighted the shortage of such data for radiotherapy small photon beams and for surface dose estimations in diagnostic and interventional radiology, leading to significant dosimetric errors that in some instances have jeopardized patient’s safety and treatment efficiency. The aim of this thesis is to investigate and determine key data for the reference and relative dosimetry of radiotherapy and radiodiagnostics beams. For that purpose the Monte Carlo system PENELOPE has been used to simulate the transport of radiation in different media and a number of experimental determinations have also been made. A review of the key data for radiotherapy beams published after the release of IAEA TRS-398 was conducted, and in some cases the considerable differences found were questioned under the criterion of data consistency throughout the dosimetry chain (from standards laboratories to the user). A modified concept of output factor, defined in a new international formalism for the dosimetry of small photon beams, requires corrections to dosimeter readings for the dose determination in small beams used clinically. In this work, output correction factors were determined, for Varian Clinac 6 MV photon beams and Leksell Gamma Knife Perfexion 60Co gamma-ray beams, for a large number of small field detectors, including air and liquid ionization chambers, shielded and unshielded silicon diodes and diamond detectors, all of which were simulated by Monte Carlo with great detail. Backscatter factors and ratios of mass energy-absorption coefficients required for surface (skin) determinations in diagnostic and interventional radiology applications were also determined, as well as their extension to account for non-standard phantom thicknesses and materials. A database of these quantities was created for a broad range of monoenergetic photon beams and computer codes developed to convolve the data with clinical spectra, thus enabling the determination of key data for arbitrary beam qualities. Data presented in this thesis has been contributed to the IAEA international dosimetry recommendations for small radiotherapy beams and for diagnostic radiology in paediatric patients.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Manuscript.
3
Schweizer, Pia. "Analyse et quantification du lithium par le développement d'un dispositif innovant de spectrométrie et microanalyse X". Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS207.pdf.
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L'analyse quantitative du lithium est aujourd'hui possible, mais repose sur l'usage de techniques destructives. Une analyse quantitative locale non-destructive est encore difficile à mettre en œuvre par les méthodes spectroscopiques classiques de laboratoire. Cette thèse vise à développer un dispositif innovant de quantification du lithium par microsonde électronique. L'implémentation d'une multicouche périodique et de fenêtres de séparation ultra fines dans un spectromètre de la microsonde de Castaing a permis la spectrométrie dans la gamme des très faibles énergies de photons X et ainsi la mesure du lithium. Malgré les difficultés qui compliquent fortement l'analyse, principalement liées aux spécificités de l'instrumentation et aux divers phénomènes physiques tels que le faible rendement de fluorescence du lithium et la forte absorption des photons caractéristiques dans l'échantillon, des premiers résultats quantitatifs ont pu être obtenus pour différents matériaux avec des fractions massiques en lithium comprises entre 4 % et 9 %. Ces résultats conduisent à des limites de détection inférieures à un pourcent. Différentes approches de quantification basées sur une mesure avec des témoins réels et sur des simulations Monte Carlo pour créer des témoins virtuels ont été mises en place. De plus, la mesure expérimentale des coefficients d'atténuation des photons dans la gamme des très faibles énergies a permis d'apporter des précisions aux bases de données existantes pour différents éléments, contribuant ainsi à l'amélioration de la précision des résultats. Malgré les défis persistants, ces travaux ouvrent la voie à de nouvelles avancées dans la quantification du lithium par microsonde électronique et constituent une première étape importante pour un futur développement de cette techniqueQuantitative analysis of lithium is feasible today, but relies on the use of destructive techniques. Local non-destructive quantitative analysis remains challenging using traditional laboratory spectroscopic methods. The aim of this thesis is to develop an innovative device for lithium quantification using electron probe microanalysis. By implementing a periodic multilayer and ultra-thin separation windows into the spectrometer of a Castaing microprobe, spectroscopy in the extreme low photon energy range, including Li K measurement was possible. Despite the significant analytical challenges, mainly linked to the specificities of the instrumentation and to various physical phenomena such as low lithium fluorescence yield and strong absorption of the characteristic photons in the sample, quantitative results were obtained for different materials with lithium mass fractions ranging from 4 % to 9 % and detection limits lower than one percent. Two different quantification approaches based on measurement with real standards and Monte Carlo simulations to create virtual standards were employed. In addition, experimental measurement of photon attenuation coefficients in the ultra-soft X-ray range provided precision to existing databases for different elements, helping to improve the accuracy of results. Despite persistent challenges, this work paves the way for further advances in lithium quantification by electron probe microanalysis and represents an important first step towards future development of this technique
4
Nordmann, Stephan. "Light absorption of atmospheric soot particles over Central Europe". Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-109901.
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Soot particles are a major absorber of shortwave radiation in the atmosphere. They exert a rather uncertain direct and semi-direct radiative effect, which causes a heating or in some cases a cooling of the atmosphere. The mass absorption coefficient is an essential quantity to describe this light absorption process. This work presents new experimental data on the mass absorption coefficient of soot particles in the troposphere over Central Europe. Mass absorption coefficients were derived as the ratio between the light absorption coefficient determined by multi angle absorption photometry (MAAP), and the soot mass concentration determined by Raman spectroscopy. The Raman method is sensitive to graphitic structures present in the particle samples, and was calibrated in the laboratory using Printex90 model particles. The mass absorption coefficients were determined for a number of seven observation sites, ranging between 3.9 and 7.4 m²/g depending on measurement site and observational period.
The highest values were found in an continentally aged air mass in winter, where we presumed soot particles to be present mainly in internal mixture.
The regional model WRF-Chem was used in conjunction with a high resolution soot emission inventory to simulate soot mass concentrations and absorption coefficients for the Central European Troposphere. The model was validated using soot mass concentrations from Raman measurements and absorption coefficients. Simulated soot mass concentrations were found to be too low by around 50 %, which could be improved by scaling the emissions by a factor of two. In contrast, the absorption coefficient was positively biased by around 20%. Adjusting the modeled mass absorption coefficient to measurements, the simulation of soot light absorption was improved.
Finally, the positive direct radiative forcing at top of the atmosphere was found to be lowered by up to 70% for the model run with adjusted soot absorption behaviour, , indicating a decreased heating effect on the atmosphere.
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Chery, Olivier. "Étude hydrodynamique et transfert de matière dans un contacteur gaz-liquide à film centrifuge dans le cadre de procédés de traitement d'effluents gazeux contenant du dioxyde de soufre et/ou des oxydes d'azote". Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_CHERY_O.pdf.
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Dans le cadre d'un programme B. R. I. T. E. De la C. C. E. , nous étudions un procédé de traitement d'effluents gazeux contenant du dioxyde de soufre et/ou des oxydes d'azote, par absorption suivie de l'oxydation de ces espèces. Dans une première phase, nous avons utilisé un contacteur gaz-liquide ayant des caractéristiques de transfert de matière élevées: le réacteur à film centrifuge. La caractérisation hydrodynamique du contacteur a permis de mettre en évidence les régimes de fonctionnement, le comportement, du réacteur piston au réacteur parfaitement agité, ainsi que les paramètres essentiels: la vitesse de rotation et la contre-pression. Nous avons ensuite déterminé les caractéristiques de transfert de matière de l'absorbeur par la mesure des coefficients volumiques de transfert de matière cote gaz et liquide. La dernière étape de cette étude a été une application du réacteur à film centrifuge à l'absorption d'un mélange dilué d'oxyde et de dioxyde d'azote dans une solution aqueuse d'urée. Il s'avère que les temps de séjour rencontrés dans le contacteur sont trop faibles pour que certaines réactions d'élimination de ces polluants puissent avoir lieu. La seconde partie a consisté à concevoir et à mettre en œuvre un réacteur à film tombant laminaire cylindrique, destiné à déterminer la cinétique de la réaction chimique suivant l'absorption du dioxyde de soufre dans une solution aqueuse acide de cérium quatre. Seules, quelques expériences ont pu être réalisées montrant que la réaction est probablement intermédiaire. D’autres expériences doivent également être menées afin de mieux caractériser ce réacteur
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Hou, Longfeng. "Etude numérique sur le modèle de coefficient d’absorption corrélé en multi spectral". Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0068.
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Le transfert radiatif dû aux gaz joue un rôle important dans les applications industrielles comme les chambres de combustion, les sciences atmosphériques, etc. Plusieurs modèles ont été proposées pour estimer les propriétés radiatives des gaz. Le plus précis est l'approche dite Raie Par Raie (RPR). Cependant, cette méthode implique un coût de calcul excessif qui la rend inappropriée pour la plupart des applications. Néanmoins, elle reste la méthode de référence que nous utiliserons pour l'évaluation d’autres modèles approchés. Le modèle de coefficient d’absorption corrélé (Ck) est généralement suffisant pour de nombreuses applications. Cette méthode est réputée précise lorsque petits gradients de température sont rencontrés au sein du gaz. Toutefois, si le milieu gazeux est soumis à d'importants gradients de température, la méthode Ck peut conduire à des erreurs qui peuvent atteindre 50% en termes de flux radiatifs par rapport à des simulations de RPR. Le but de cette thèse est de proposer une version améliorée de la méthode Ck, appelée l'approche de coefficient d’absorption corrélé en multi spectral (MSCk). La principale différence entre les modèles Ck et MSCk est que, dans l'approche Ck les intervalles spectraux sur lesquels les propriétés radiatives des gaz sont moyennées sont choisis contiguës alors que, dans l’approche MSCk, ces intervalles sont construits afin d'assurer que le coefficient d'absorption soit corrélé sur ces intervalles. Par conséquent, l'hypothèse de corrélation dans l’approche MSCk est mieux adaptée que dans l’approche Ck. La construction de ces intervalles spectraux (en utilisant la méthode de classification automatique de données fonctionnelles) est détaillée. Cette approche est évaluée par rapport à la référence RPR dans plusieurs cas test. Ces cas traitent de mélanges de gaz (H2O-N2 et H2O-CO2-N2) dans l’intervalle de température [300-3000K]. Les résultats montrent que la méthode MSCk permet d'obtenir de meilleures précisions que les méthodes Ck tout en restant acceptable en termes de coût de calculRadiative heat transfer of gas plays an important role in industrial applications such as in combustion chambers, atmospheric sciences, etc. Several models [11] have been proposed to estimate the radiative properties of gases. The most accurate one is the Line-By-Line (LBL) approach. However, this technique involves excessive computation cost which makes it inappropriate for most applications. Nevertheless, it remains the reference approach for the assessment of other approximate models. The Correlated k-distribution method (Ck) [11] was shown to be a relevant choice for many applications. This method performs usually well, when only small temperature gradients are involved [21]. However, if the gaseous medium is subject to large temperature gradients, it may lead to errors that can reach 50% in terms of radiative heat fluxes when compared to LBL simulations [21]. The aim of the present paper is to propose an enhanced version of the Ck method, called the Multi-Spectral Correlated k-distribution approach (MSCk). The main difference between Ck and MSCk models is that in the Ck approach spectral intervals over which the radiative properties of the gas are averaged are chosen contiguous whereas, in the MSCk technique, those intervals are built in order to ensure that the absorption coefficient are scaled over them [27]. Accordingly, the usual assumption of correlated spectrum used in k-distribution approaches for the treatment of non uniformities is more acceptable in the MSCk case than in the Ck one. The building of those spectral intervals (using Functional Data Clustering, [52]) is detailed and the approach is assessed against LBL reference data in several test cases. These cases involve H2O-N2 and H2O-CO2-N2 mixtures in the [300-3000K] temperature range. Results show that the MSCk method enables to achieve better accuracies than Ck methods while remaining acceptable in terms of computational cost
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Derdar, Mawaheb M. Zarok. "Experimental and kinetic modelling of multicomponent gas/liquid ozone reactions in aqueous phase. Experimental investigation and Matlab modelling of the ozone mass transfer and multicomponent chemical reactions in a well agitatated semi-batch gas/liquid reactor". Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4872.
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Due to the ever increasing concerns about pollutants and contaminants found in water, new treatment technologies have been developed. Ozonation is one of such technologies. It has been widely applied in the treatment of pollutants in water and wastewater treatment processes. Ozone has many applications such as oxidation of organic components, mineral matter, inactivation of viruses, cysts, bacteria, removal of trace pollutants like pesticides and solvents, and removal of tastes and odours. Ozone is the strongest conventional oxidant that can result in complete mineralisation of the organic pollutants to carbon dioxide and water. Because ozone is unstable, it is generally produced onsite in gas mixtures and is immediately introduced to water using gas/liquid type reactors (e.g. bubble columns). The ozone reactions are hence of the type gas liquid reactions, which are complex to model since they involve both chemical reactions, which occur in the liquid phase, and mass transfer from the gas to the liquid phase. This study focuses on two aspects: mass transfer and chemical reactions in multicomponent systems. The mass transfer parameters were determined by experiments under different conditions and the chemical reactions were studied using single component and multicomponent systems. Two models obtained from the literature were adapted to the systems used in this study.
Mass transfer parameters in the semi-batch reactor were determined using oxygen and ozone at different flow rates in the presence and absence of t-butanol. t-Butanol is used as a radical scavenger in ozonation studies and it has been found to affect the gas¿liquid mass transfer rates. An experimental study was carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, kL. The mass transfer coefficient increased by about 60% for oxygen and by almost 50% for ozone. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, kLa.
The multicomponent ozonation was studied with two systems, slow reactions when alcohols were used and fast reactions when endocrine disrupting compounds were used.
ii
These experiments were simulated by mathematical models. The alcohols were selected depending on their volatilization at different initial concentrations and different gas flow rates. The degradation of n-propanol as a single compound was studied at the lowest flow rate of 200 mL/min. It was found that the degradation of n-propanol reached almost 60% within 4 hours. The degradation of the mixture was enhanced with an increase in the number of components in the mixture. It was found that the degradation of the mixture as three compounds reached almost 80% within four hours while the mixture as two compounds reached almost 70%. The effect of pH was studied and it was found that an increase in pH showed slight increase in the reaction. Fast reactions were also investigated by reacting endocrine disrupting chemicals with ozone. The ozone reactions with the endocrine disrupters were studied at different gas flow rates, initial concentrations, ozone concentrations and pH. The degradation of 17¿-estradiol (E2) as a single compound was the fastest, reaching about 90% removal in almost 5 minutes. However estrone (E1) degradation was the lowest reaching about 70% removal at the same time. The degradation of mixtures of the endocrine disruptors was found to proceed to lower percentages than individual components under the same conditions. During the multicomponent ozonation of the endocrine disruptors, it was found that 17¿-estradiol (E2) converted to estrone (E1) at the beginning of the reaction.
A MATLAB code was developed to predict the ozone water reactions for single component and multicomponent systems. Two models were used to simulate the experimental results for single component and multicomponent systems. In the case of single component system, good simulation of both reactions (slow and fast) by model 1 was obtained. However, model 2 gave good agreement with experimental results only in the case of fast reactions. In addition, model 1 was applied for multicomponent reactions (both cases of slow and fast reaction). In the multicomponent reactions by model 1, good agreement with the experimental results was also obtained for both cases of slow and fast reactions.Ministry of Higher Education in Libya and the Libyan Cultural Centre and Educational Bureau in London.
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Derdar, Mawaheb M. Zarok. "Experimental and kinetic modelling of multicomponent gas/liquid ozone reactions in aqueous phase : experimental investigation and Matlab modelling of the ozone mass transfer and multicomponent chemical reactions in a well agitated semi-batch gas/liquid reactor". Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4872.
Texto completo da fonteResumo:
Due to the ever increasing concerns about pollutants and contaminants found in water, new treatment technologies have been developed. Ozonation is one of such technologies. It has been widely applied in the treatment of pollutants in water and wastewater treatment processes. Ozone has many applications such as oxidation of organic components, mineral matter, inactivation of viruses, cysts, bacteria, removal of trace pollutants like pesticides and solvents, and removal of tastes and odours. Ozone is the strongest conventional oxidant that can result in complete mineralisation of the organic pollutants to carbon dioxide and water. Because ozone is unstable, it is generally produced onsite in gas mixtures and is immediately introduced to water using gas/liquid type reactors (e.g. bubble columns). The ozone reactions are hence of the type gas liquid reactions, which are complex to model since they involve both chemical reactions, which occur in the liquid phase, and mass transfer from the gas to the liquid phase. This study focuses on two aspects: mass transfer and chemical reactions in multicomponent systems. The mass transfer parameters were determined by experiments under different conditions and the chemical reactions were studied using single component and multicomponent systems. Two models obtained from the literature were adapted to the systems used in this study. Mass transfer parameters in the semi-batch reactor were determined using oxygen and ozone at different flow rates in the presence and absence of t-butanol. t-Butanol is used as a radical scavenger in ozonation studies and it has been found to affect the gas-liquid mass transfer rates. An experimental study was carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, kL. The mass transfer coefficient increased by about 60% for oxygen and by almost 50% for ozone. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, kLa. The multicomponent ozonation was studied with two systems, slow reactions when alcohols were used and fast reactions when endocrine disrupting compounds were used. ii These experiments were simulated by mathematical models. The alcohols were selected depending on their volatilization at different initial concentrations and different gas flow rates. The degradation of n-propanol as a single compound was studied at the lowest flow rate of 200 mL/min. It was found that the degradation of n-propanol reached almost 60% within 4 hours. The degradation of the mixture was enhanced with an increase in the number of components in the mixture. It was found that the degradation of the mixture as three compounds reached almost 80% within four hours while the mixture as two compounds reached almost 70%. The effect of pH was studied and it was found that an increase in pH showed slight increase in the reaction. Fast reactions were also investigated by reacting endocrine disrupting chemicals with ozone. The ozone reactions with the endocrine disrupters were studied at different gas flow rates, initial concentrations, ozone concentrations and pH. The degradation of 17β-estradiol (E2) as a single compound was the fastest, reaching about 90% removal in almost 5 minutes. However estrone (E1) degradation was the lowest reaching about 70% removal at the same time. The degradation of mixtures of the endocrine disruptors was found to proceed to lower percentages than individual components under the same conditions. During the multicomponent ozonation of the endocrine disruptors, it was found that 17β-estradiol (E2) converted to estrone (E1) at the beginning of the reaction. A MATLAB code was developed to predict the ozone water reactions for single component and multicomponent systems. Two models were used to simulate the experimental results for single component and multicomponent systems. In the case of single component system, good simulation of both reactions (slow and fast) by model 1 was obtained. However, model 2 gave good agreement with experimental results only in the case of fast reactions. In addition, model 1 was applied for multicomponent reactions (both cases of slow and fast reaction). In the multicomponent reactions by model 1, good agreement with the experimental results was also obtained for both cases of slow and fast reactions.
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MENDES, Marcus Vinícius Araújo da Silva. "Avaliação das propriedades de transporte de massa contendo adições minerais". Universidade Federal de Goiás, 2009. http://repositorio.bc.ufg.br/tede/handle/tde/1353.
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Previous issue date: 2009-10-06The durability of reinforced concrete structures is damaged by the degrading action of the penetration of substances in the form of gases, vapors and liquids through the pores and cracks. It is known that water both in its pure form or containing dissolved ions such as chloride, sulphate, carbon dioxide or oxygen ions, can compromise the durability of concrete structures. In reinforced concrete structures at the marine environment, for example, the towers of wind power plants, this degradation can be more intense and accelerated. Thus, in the present study were analyzed concretes with different mineral additions (silica fume, blast furnace slag) and water / binder ratios (0.35, 0.45 and 0.55), with the objective to verify if the inside and cover thickness of concrete have some effect on the mechanisms of transport and also the effect of carbonation (only for concrete with w/b equal to 0.55) in the surface layer of concrete is important enough to make dificult the entry of aggressive agents in concrete. For this, the following tests to evaluate the mass transport in concrete were performed: capillary water absorption (NBR 9779:1995), water penetration under pressure (NBR 10787:1994), air permeability (method Figg), penetrability of chloride ion (ASTM C 1202: 2009), non-steadystate migration test (NT BUILD 492:1999). As a result, it was found that the mineral addition used generally provided an improvement in front of the concrete mechanisms of mass transport. In one of the properties, namely the diffusion coefficient (non-steady-state migration) of concrete with the use of silica fume and blast furnace slag, this has been reduced dramatically, around 11 times for the concrete with w/b equal to 0.55, when it is compared with concrete without mineral addition. It was observed that the inner region of concrete behaved better, in an unexpected way, than concrete cover region for some properties (capillary absorption, water penetration under pressure, penetration of chloride ions). From this conclusion, it can be said that the inner part of concrete is composed of transition zones (aggregated interface / mortar) exposed to facilitate the entry of fluids, gases and ions. About the effect of carbonation, this affected the capillary absorption and air permeability. The results led to explain that the clogging of the pores resulting from the product of carbonation (CaCO3), promoted the refinement of the pores, thus increasing capillary force and, consequently, increasing the capillary absorption. However, for air permeability this effect has damaged the passage of air through the surface layer. Finally, it is important noting that significant correlations were found among tests that evaluated the mechanisms of mass transport, namely, penetration of chloride ions and capillary absorption, diffusion coefficient (non-steady-state migration) and capillary absorption, permeability air and water penetration under pressure, penetration of chloride ions and the diffusion coefficient.
A durabilidade das estruturas de concreto armado é prejudicada pela ação deteriorante da penetração de substâncias na forma de gases, vapores e líquidos através de poros e fissuras. Sabe-se que a água, tanto no seu estado puro ou com íons dissolvidos, como os cloretos, sulfato, dióxido de carbono ou oxigênio, pode comprometer a durabilidade das estruturas de concreto. Em estruturas de concreto armado localizadas em ambiente marítimo como, por exemplo, as torres de energia eólica, essa deterioração pode ser mais intensa e acelerada. Diante disso, no presente trabalho foram analisados concretos com diferentes adições minerais (sílica ativa e escória de alto-forno) e relações água/aglomerante (0,35; 0,45 e 0,55), tendo como objetivo principal verificar se a parte interna e o cobrimento do concreto exercem algum efeito nos mecanismos de transporte e, se o efeito da carbonatação (somente para concretos de relação a/g igual a 0,55) na camada superficial do concreto é relevante a ponto de dificultar a entrada de agentes agressivos no concreto. Para isso, foram realizados os seguintes ensaios para avaliar o transporte de massa no concreto: absorção de água por capilaridade (NBR 9779:1995), penetração de água sob pressão (NBR 10787:1994), permeabilidade ao ar (método de Figg), penetrabilidade de cloretos (ASTM C 1202: 2009), ensaio de migração em regime não estacionário (NT BUILD 492:1999). Como resultado constatou-se que as adições minerais empregadas propiciaram de maneira geral uma melhoria dos concretos frente aos mecanismos de transporte de massa. Em uma das propriedades avaliadas, a saber, o coeficiente de difusão (migração regime não estacionário) dos concretos com o emprego de sílica ativa e escória de alto-forno, esse foi reduzido drasticamente, em torno de 11 vezes para os concretos com relação a/ag igual a 0,55, quando comparado com os concretos sem adição mineral. Quanto à região do concreto, notou-se para algumas propriedades (absorção capilar, penetração de água sob pressão, penetrabilidade de cloretos) que a região interna comportou-se melhor, de maneira inesperada, que a região do cobrimento. Diante dessa conclusão, criou-se uma hipótese para tal comportamento que consistiu em afirmar que a parte interna é composta por zonas de transição (interface agregado/pasta) expostas que facilitam a entrada de fluidos, gases e íons. Já com relação ao efeito da carbonatação, esta afetou a absorção capilar e a permeabilidade ao ar. Os resultados levaram a explicar que a colmatação dos poros, advindos do produto (CaCO3) da carbonatação promoveu o refinamento dos poros, aumentando, assim, a força capilar e, conseqüentemente, o aumento da absorção capilar. No entanto, para permeabilidade ao ar esse efeito dificultou a passagem de ar através da camada superficial. Por último, cabe destacar, que correlações importantes foram obtidas entre os ensaios que avaliaram os mecanismos de transporte de massa, a saber, penetrabilidade de cloretos e absorção capilar, coeficiente de difusão (migração regime não estacionário) e absorção capilar, permeabilidade ao ar e penetração de água sob pressão, penetrabilidade de cloreto e coeficiente de difusão.
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Garcia, Fernandez Carlos. "Modeling Optical Properties of Combustion Soot emitted in the Troposphere". Thesis, Besançon, 2015. http://www.theses.fr/2015BESA2040/document.
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Ce travail concerne la modélisation, à l’échelle moléculaire, de l’interaction entre des nanoparticules carbonées et le rayonnement électromagnétique. Le but est d’aider à la compréhension des propriétés optiques des particules de suie afin de mieux quantifier l’influence des suies sur l’atmosphère et le climat. L’étude de l’interaction rayonnement/particules de suie fraîche a été effectuée par la méthode PDI ; il a été montré que : i) le coefficient d’absorption massique (MAC) des particules de suie dépend de la répartition des atomes dans la particule et de leurs liaisons, en particulier entre 200 et 350 nm ; ii) le MAC diffère selon que le cœur de la particule carbonée est occupé ou non par des plans graphitiques ; iii) un modèle analytique n’est pas adapté pour calculer le MAC d’une nanoparticule carbonée présentant des défauts structuraux. De plus, des méthodes de chimie quantique ont été utilisées pour caractériser le vieillissement des suies. Les résultats montrent que : i) NO, Cl, et HCl sont physisorbées sur une surface carbonée parfaite alors que sur une surface défective, ces espèces sont chimisorbées et conduisent à une modification de la surface ; ii) la présence de Cl conduit à un piégeage fort des molécules d’eau supérieur à celui obtenu lorsqu’un site oxygéné est présent sur la surface carbonée, expliquant ainsi le caractère hydrophile des suies émises lors d’incendies dans des milieux industriels. Enfin, la méthode PDI a été appliquée au calcul de la polarisabilité de HAP afin d’interpréter des spectres d’absorption des grains carbonés du milieu interstellaire, en incluant des molécules pour lesquelles aucune donnée n’était actuellement disponibleThis work concerns the modeling, at the molecular level, of the interaction between carbonaceous particles of nanometric size and the electromagnetic radiation. The goal is to improve our understanding of the optical properties of soot particles, to better quantify the influence of soot on the atmosphere and on climate change. The study of the interaction between radiation and fresh soot particles was carried out using the point dipole interaction method; it has been shown that: i) the mass absorption coefficient (MAC) of these soot nanoparticles may significantly depend on their atomistic details, especially between 200 and 350 nm; ii) the MAC depends on whether the heart of the carbonaceous particle is occupied or not by graphite planes; iii) an analytical model is not suitable for calculating the MAC of carbonaceous nanoparticles having structural defects. In addition, quantum chemical methods have been used to characterize the ageing of soot. The results obtained are i) NO, Cl, and HCl are physisorbed on a perfect carbonaceous surface whereas on a defective surface, these species are chemisorbed and lead to a modification of the surface; ii) on a carbonaceous surface, the presence of adsorbed Cl atoms leads to a strong trapping of the surrounding water molecules. This may be related to the highly hydrophilic nature of soot emitted during fires in industrial environments. Finally, the PDI method was applied to calculate the polarizability of PAHs to help at interpreting the absorption spectra of carbonaceous grains in the interstellar medium, including molecules for which no data was currently available
Livros sobre o assunto "Mass absorption coefficients"
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Singh, Jag J. Low-energy gamma ray attenuation characteristics of aviation fuels. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1990.
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Singh, Jag J. Low-energy gamma ray attenuation characteristics of aviation fuels. Hampton, Va: Langley Research Center, 1990.
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Singh, Jag J. Low-energy gamma ray attenuation characteristics of aviation fuels. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1990.
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Skiba, Grzegorz. Fizjologiczne, żywieniowe i genetyczne uwarunkowania właściwości kości rosnących świń. The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 2020. http://dx.doi.org/10.22358/mono_gs_2020.
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Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.
Capítulos de livros sobre o assunto "Mass absorption coefficients"
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Chipera, Steve J., e David L. Bish. "Measurement of Mass Absorption Coefficients Using Compton-Scattered Cu Radiation in X-Ray Diffraction Analysis". In Advances in X-Ray Analysis, 325–35. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3744-1_36.
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Wertz, David L., Charles B. Smithhart e Stacey L. Wertz. "X-Ray Mass Absorption Coefficients: Measurements and Uses in the Quantitative Diffraction Analysis of Pyrite in Coals". In Advances in X-Ray Analysis, 475–83. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-9996-4_53.
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Willis, J. P. "Mass Absorption Coefficient Determination Using Compton Scattered Tube Radiation: Applications, Limitations and Pitfalls". In Advances in X-Ray Analysis, 243–61. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3744-1_27.
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Birks, L. S., e John Criss. "Mass Photoelectric Absorption Coefficients". In Practical Handbook of Spectroscopy, 701–78. Routledge, 2017. http://dx.doi.org/10.1201/9780203742433-44.
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Kirk, John T. O. "The Relationship between the Inherent and the Apparent Optical Properties of Surface Waters and its Dependence on the Shape of the Volume Scattering Function". In Ocean Optics. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195068436.003.0006.
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Let us begin by reminding ourselves just what we mean by “the inherent optical properties” and “the apparent optical properties” of surface waters. The inherent optical properties are those that belong to the aquatic medium itself: properties that belong to a small sample of the aquatic medium taken out of the water body just as much as they belong to a great mass of the medium existing within the water body itself. The properties of particular concern to us are the absorption coefficient, a, the scattering coefficient, b, and the volume scattering function, β(θ). The absorption coefficient at a given wavelength is a measure of the intensity with which the medium absorbs light from a parallel beam per unit pathlength of medium (see Eq. 1.18). The scattering coefficient at a given wavelength is a measure of the intensity with which the medium scatters light from a parallel beam per unit pathlength of medium (see Eq. 1.17). Both a and b have the units, m-1. The normalized volume scattering function specifies the angular (θ) distribution of single-event scattering around the direction of a parallel incident beam. It is often normalized to total scattering and referred to as the scattering phase function, P(θ) (see Eq. 1.21). Since these properties belong, as I have already said, to a small sample of the medium, just as much as they do to a great slab of ocean, they can be measured in the laboratory. The absorption coefficients at various wavelengths can be measured with a suitable spectrophotometer: the scattering coefficient and the volume scattering function can be measured with a light scattering photometer. The apparent optical properties are not properties of the aquatic medium as such although they are closely dependent on the nature of the aquatic medium. In reality they are properties of the light field that, under the incident solar radiation stream, is established within the water body.
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Bentham Science Publisher, Bentham Science Publisher. "Mass Absorption Coefficient and Density of the Element". In Multifunctional Two- and Three-Dimensional Polycrystalline X-Ray Diffractometry, 150–51. BENTHAM SCIENCE PUBLISHERS, 2012. http://dx.doi.org/10.2174/978160805076511101010150.
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Peña, Rosaura, Lourdes Hurtado, Rubi Romero e Reyna Natividad. "Absorption and reaction of CO2 in capillaries". In CIERMMI Women in Science Engineering and Technology TXV, 51–74. ECORFAN, 2021. http://dx.doi.org/10.35429/h.2021.6.51.74.
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The process of carbon dioxide (CO2) reduction to value-added chemicals is being extensively studied worldwide. The main purpose is to decrease emissions to the environment that are associated with global warming, as well as the creation of renewable and sustainable energy sources. In the aforementioned process, the absorption of CO2 is of paramount importance as well as the reactor where the CO2 conversion takes place. In this context, the objective of this chapter is to present and analyze the results of the CO2 absorption in alkaline solutions in capillary reactors. A hydrodynamic study is included in order to establish the operational window of liquid and gas velocities in order to achieve the Taylor flow regime. All experiments were conducted in a capillary reactor (dc = 3 mm). The studied variables were temperature, NaOH concentration (0-0.75 M) and capillary length (300 and 100 mm). It was found that the volumetric mass transfer coefficient of the absorption of CO2 in water increases when the temperature decreases, while the CO2 absorption in NaOH solutions increases directly with temperature. By means of the Ha number, it was concluded that the mass transfer controlled the absorption process when using alkaline solutions.
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"Ss". In Biochemistry and Molecular biology, editado por Dr AD Smith, SP Datta, Dr G. H. Smith, P. N. Campbell, Dr R. Bentley, Dr HA McKenzie, Dr DA Bender et al., 582–631. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780198547686.003.0019.
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Abstract s symbol for 1 second (def. 1). 2 solid state (in a chemical equation). 3 atomic orbital corresponding to an orbital angular momentum quantum number([)= 0. 4 singlet (in nuclear magnetic resonance spectroscopy). 5 strong absorption (in infrared spectroscopy). s symbol for 1 sedimentation coefficient. 2 solubility. 3 (in monosaccharide nomenclature) the septanose form; it is suffixed to the symbol for the corresponding monosaccharide; e.g. glucoseptanose is symbolized as Glcs. 4 specific entropy (i.e. entropy/mass). 5 spin quantum number.
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Khvorostyanov, Vitaly I., e Kenneth Sassen. "Microphysical Processes in Cirrus and Their Impact on Radiation: A Mesoscale Modeling Perspective". In Cirrus. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195130720.003.0023.
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The impact of cloudiness on the global radiative budget and its climatic consequences have been widely discussed during the last three decades. It was gradually recognized that the climatic effect of cloudiness depends on its height: low- and middle-level cloudiness have a total cooling effect on the Earth climatic system, while the upper-level clouds, cirrus, may have mostly a warming effect (IPCC 1995). The net effect of cirrus (i.e., warming or cooling), is much less clear because neither their microphysical and optical properties, nor the processes that govern their formation, are well understood and parameterized in climate models. These uncertainties have stimulated several major field projects performed within the International Satellite Cloud Climatology Project (ISCCP; Rossow and Schiffer 1991) with subsequent data analysis reports [e.g., FIRE IFO-I (1990), FIRE IFO-II (1995), and EUCREX (Raschke et al. 1996)]. The relevant theoretical works, and even the simplest climate models, indicate that the climatic impact of cirrus depends on their microstructure: clouds composed of small crystals with effective radii less than about 16 μm have a total cooling effect, but clouds of larger crystals have a warming effect (Stephens et al. 1990). It was shown that the total cloud forcing at the top of the atmosphere (TOA) is positive from a few to a few tens of watts per square meter for the large crystals and decreases with decreasing crystal radius (Fu and Liou 1993). Most of the previous theoretical studies of cirrus radiative properties, after choosing some model of microphysics and some values for the mass extinction and absorption coefficients, then prescribed them to the whole cloud, neglecting any vertical variations. Simulations with general circulation models (GCMs) showed that cirrus clouds with their optical properties parameterized in such a way (i.e., constant with height) have a total warming effect and positive feedbacks with respect to greenhouse gas-induced global warming (e.g., Ramanathan et al. 1983; Wetherald and Manabe 1988). Today, the estimation of the warming/cooling effect of cirrus has become even more complicated due to two factors. First, for many years the usual in situ probes allowed the measurement of ice crystals with radii only larger than 25-50 μm, so the smallest and most optically and radiatively active crystals were unresolved.
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Gómez-Hernández, Jesús, Alhi Kholghi, Mercedes de Vega, Javier Villa Briongos e Ronan Grimes. "STUDYING CARBON DIOXIDE AND ACETONE MIXTURES IN A SINGLE-STAGE ABSORPTION-COMPRESSION CYCLE FOR HEATING AND COOLING APPLICATIONS". In Proceedings of the 7th International Seminar on ORC Power System (ORC 2023), 458–65. 2024a ed. Editorial Universidad de Sevilla, 2024. http://dx.doi.org/10.12795/9788447227457_75.
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This communication analyzes the performance of a zeotropic fluid, composed by the mixture of carbon dioxide and acetone, in a vapor compression cycle with a solution circuit. The working fluid is characterized by a high temperature glide that depends on the mixture composition. The high critical temperature of the acetone and the good thermal properties of carbon dioxide makes this mixture a promising heat transfer fluid for industrial heat pumps that need to supply energy for heating and cooling processes. The heat pump analyzed has these components: evaporator, compressor, condenser, two internal heat exchangers and an expansion valve. In addition, a second liquid line with a solution pump is used to circulate the liquid from the gas-liquid separator to an internal heat exchanger, and then, to the condenser. In this way, the gas-liquid separator allows the fluid to leave the evaporator as a vapor-liquid mixture. This heat pump configuration working with the CO2/acetone mixture could provide the energy needs of an industry that requires both heating and cooling. Depending on the binary mixture composition, the source and sink temperatures change as well as the coefficient of performance. For instance, an 55% CO2/45% acetone in mass fraction, can provide heat to the sink at an average thermodynamic temperature of 110ºC, and refrigeration at an average thermodynamic temperature of 0ºC, showing a total COP of 2.55. This configuration would work at a high pressure of 40 bar and a low pressure of 10 bar.
Trabalhos de conferências sobre o assunto "Mass absorption coefficients"
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Chakraborty, Debamitra, Bradley N. Mills, Jing Cheng, Ivan Komissarov, Scott Gerber e Roman Sobolewski. "Terahertz Time-Domain Imaging for Radiotherapy Treatment Monitoring in Pancreatic Ductal Adenocarcinoma". In CLEO: Applications and Technology, ATh1B.4. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_at.2024.ath1b.4.
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Terahertz time-domain imaging was performed of stereotactic body radiotherapy-treated murine pancreatic ductal adenocarcinoma (PDAC) with a high spatial resolution. To generate 2D maps of the tissue samples, the refractive index and absorption coefficient were used as imaging markers extracted with the maximum a-posteriori probability (MAP) estimation algorithm. The results were then compared with the terahertz maps of untreated murine PDAC tissue samples and demonstrated that terahertz imaging can probe physical changes with high sensitivity in the tissue post treatment.
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Karunarathne, Sumudu S., Dag A. Eimer e Lars Erik Øi. "Model uncertainty of interfacial area and mass transfer coefficients in absorption column packings". In The 58th Conference on Simulation and Modelling (SIMS 58) Reykjavik, Iceland, September 25th – 27th, 2017. Linköping University Electronic Press, 2017. http://dx.doi.org/10.3384/ecp17138144.
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BABIKIAN, D., D. EDWARDS, S. KARAM, C. WOOD e G. SAMUELSEN. "Gravimetric and radiometric measurements of soot mass absorption coefficients in a spray combustor flame". In 26th Aerospace Sciences Meeting. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1988. http://dx.doi.org/10.2514/6.1988-539.
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Ganapathy, Harish, Amir Shooshtari, Serguei Dessiatoun, Mohamed Alshehhi e Michael M. Ohadi. "Experimental Investigation of Enhanced Absorption of Carbon Dioxide in Diethanolamine in a Microreactor". In ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icnmm2013-73162.
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Natural gas in its originally extracted form comprises carbon dioxide and hydrogen sulfide as small, but non-negligible fractions of its dominant component, methane. Natural gas in the above form is typically subjected to a sweetening process that removes these acid gases. Microscale technologies have the potential to substantially enhance mass transport phenomena on account of their inherently high surface area to volume ratio. The present work reports the mass transfer characteristics during gas-liquid absorption in a microreactor. The absorption of CO2 mixed with N2 into aqueous diethanolamine was investigated in a single straight channel having a hydraulic diameter of 762 micrometer and circular cross-sectional geometry. The performance of the reactor was characterized with respect to the absorption efficiency and mass transfer coefficient. Close to 100% absorption efficiency was obtained under optimum operating conditions. Shorter channel lengths were observed to yield enhanced values of mass transfer coefficient on account of the improved utilization of the liquid reactants’ absorption capacity for a given reactor volume. In comparison to the 0.5 m long channel, the mass transfer coefficients with the 0.3 m and 0.1 m channels were higher on an average by 35.2% and 210%, respectively. Parametric studies investigating the effects of phase superficial velocity, liquid and gas phase concentration were performed. The mass transfer coefficients achieved using the present minichannel reactor were 1–3 orders of magnitude higher than that reported using conventional gas-liquid absorption systems.
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Wang, Wei-zhi, Chun-guang Yang e Jin-rui Zhang. "Volumetric Mass Transfer Coefficients of Dilute SO2 Absorption into Sodium Alkali Solution in Packed Column". In 2010 International Conference on Digital Manufacturing and Automation (ICDMA 2010). IEEE, 2010. http://dx.doi.org/10.1109/icdma.2010.299.
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Esfahany, Mohsen Nasr, e Elahe Fadaie. "EXPERIMENTAL INVESTIGATION OF THE CONVECTIVE MASS TRANSFER COEFFICIENTS FOR CO2 ABSORPTION IN Fe3O4/H2O NANOFLUIDS". In Proceedings of CONV-14: International Symposium on Convective Heat and Mass Transfer. June 8 - 13, 2014, Kusadasi, Turkey. Connecticut: Begellhouse, 2014. http://dx.doi.org/10.1615/ichmt.2014.intsympconvheatmasstransf.820.
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Yang, Gang, e Changying Zhao. "Experimental Study of Wide-Range Spectral Radiation Properties of Air Plasma Sprayed Thermal Barrier Coatings". In ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/mnhmt2013-22041.
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In this paper the radiative properties of air plasma sprayed (APS) thermal barrier coatings are investigated by measuring the spectral diffuse reflectance and transmittance of samples with various thickness and porosities in a broad spectral band ranging from 0.25 to 15μm. The spectral absorption and scattering coefficients are obtained by a four flux model based on the experimental data. The results show that the porous zirconia ceramics exhibits high scattering coefficient (> 15000 m−1) and low absorption coefficient (< 500 m−1) in the spectral range from 0.5 to 6μm, and the corresponding spectral scattering albedo reaches up to 0.99. In addition, this study also found that the spectral scattering coefficient increases with increasing porosity, while the spectral absorption coefficient is not quite sensitive to the change of porosity. This result confirms the fact that scattering is mainly caused by the refractive index mismatch between bulk YSZ and internal void. Spectral scattering coefficient heavily depends on the microstructures of coatings, i.e., pore size, porosity and pore distribution, and this will in turn considerably affect the thermal radiation heat transfer inside the coating.
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More, Chaitali V., Rajkumar M. Lokhande e Pravina P. Pawar. "Mass energy-absorption coefficients and average atomic energy-absorption cross-sections for amino acids in the energy range 0.122-1.330 MeV". In INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC 2015): Proceeding of International Conference on Condensed Matter and Applied Physics. Author(s), 2016. http://dx.doi.org/10.1063/1.4946214.
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Ganapathy, Harish, Amir Shooshtari, Serguei Dessiatoun, Mohamed Alshehhi e Michael M. Ohadi. "Experimental Investigation of Advanced Microscale Reactors for Enhanced Carbon Capture and Natural Gas Sweetening Applications". In ASME 2013 7th International Conference on Energy Sustainability collocated with the ASME 2013 Heat Transfer Summer Conference and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/es2013-18394.
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There is an active need to develop compact mass transfer systems for high efficiency gas-liquid absorption applications, such as solvent-based carbon capture and natural gas sweetening processes. The present paper focuses on the absorption of carbon dioxide in aqueous diethanolamine using microreactors having hydraulic diameters of 762, 508 and 254 μm. The mass transfer phenomenon was studied and characterized with respect to absorption efficiency and mass transfer coefficient. Parametric studies were conducted varying the liquid and gas phase concentrations. Liquid-side volumetric mass transfer coefficients as high as 620 s−1 were achieved, which is between 2–3 orders of magnitude higher than that reported for most conventional gas-liquid absorption systems. High levels of absorption efficiency, close to 100%, were observed under certain operating conditions. The presently observed process intensification was attributed to an increase in the specific interfacial area with reduction in the channel diameter.
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Zhang, Yafei, Qulan Zhou, Yi Zhang, Qinxin Zhao e Shi’en Hui. "The Corresponding Relationship Between Heat, Mass Transfer Coefficients and the Flow Regime in Dual-Contact-Flow Absorption Tower". In ASME 2011 Power Conference collocated with JSME ICOPE 2011. ASMEDC, 2011. http://dx.doi.org/10.1115/power2011-55349.
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The flow, heat and mass transfer performance under different nozzle arrays in the dual-contact-flow absorption tower has been studied, together with the interrelation between the probability dense function (PDF) and the flow, heat and mass transfer characteristics. The experimental results show that, for the same nozzle array, both the heat and mass transfer coefficients (h and hm) increase with the gas velocity increasing at first; However, both coefficients (h and hm) start to decrease due to the reduction of the liquid-gas contact time after approaching a certain extent. Moreover, with the increase of liquid injection rate νp0, the two coefficients (h and hm) decrease, while the total heat and mass transfer values rise. In addition, the mass transfer coefficient decrease with the increase of nozzle number. In the absorption tower, the leading role gradually transfers to gas phase from liquid phase with the increase of gas velocity. The flow regimes’ transition process can be explained as follows: the liquid column flow type, the liquid screen flow type, the convergent liquid screen flow type, and the gasping flow type. Moreover, the increase of gas velocity has effects on the probability dense function (PDF). With the flow regimes’ transition, change of PDF performs as follows: the number of the PDF peaks increases from one to a larger quantity and finally decreases to a single one after that; the average pressure drop ΔPmean increases as well as the peak-peak spacing δpeak. However, the pressure drop distribution range lΔP first increases and then decreases.
Relatórios de organizações sobre o assunto "Mass absorption coefficients"
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Higgins, P. D., F. H. Attix, J. H. Hubbell, S. M. Seltzer, M. J. Berger e C. H. Sibata. Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV. Gaithersburg, MD: National Institute of Standards and Technology, 1991. http://dx.doi.org/10.6028/nist.ir.4680.
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Higgens, P. D., F. H. Attix, J. H. Hubbell, S. M. Seltzer, M. J. Berger e C. H. Sibata. Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV. Gaithersburg, MD: National Institute of Standards and Technology, 1992. http://dx.doi.org/10.6028/nist.ir.4812.
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Hubbell, J. H., e S. M. Seltzer. Tables of x-ray mass attenuation coefficients and mass energy-absorption coefficients 1 keV to 20 MeV for elements Z = 1 to 92 and 48 additional substances of dosimetry interest. Gaithersburg, MD: National Institute of Standards and Technology, 1995. http://dx.doi.org/10.6028/nist.ir.5632.
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Salonvaara, Mikael, e André Desjarlais. The impact of the solar absorption coefficient of roof and wall surfaces on energy use and peak demand. Department of the Built Environment, 2023. http://dx.doi.org/10.54337/aau541650886.
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Climate change, electrification to decarbonize the building sector, and the rise of renewable energy sources have made reducing the peak demand even more important than solely reducing the overall energy use. Solar radiation can have a significant impact on the energy use of buildings. However, previous studies on solar absorption in building envelopes have focused on cool roofs. Less effort has been made to evaluate the impact of solar radiation on heat loss and gain on walls. This paper summarizes a preliminary study to estimate the magnitude of the benefit low solar absorptance surfaces have on reducing peak demand and focuses on simulating a residential building with two types of U.S. code-compliant wall structures, a standard lightweight wall assembly, and a thermally massive mass timber wall, to evaluate the impact of the solar absorption coefficient of the surfaces on the heating and cooling energy use and peak demand. This effort aimed to identify whether a more comprehensive study should be undertaken to develop further the calculation tools previously developed for estimating the energy benefits for roofing systems in the U.S. by adding a similar tool for wall assemblies. Reducing the solar absorption coefficient from 0.9 to 0.3 resulted in up to 46% lower cooling demand and a 70% increase in heating demand depending on the climate. Peak demand reductions for heating and cooling energy were similar to the reduction in heating or cooling energy use. However, the annual energy use changed up to only 12% as lowering the solar absorption coefficient reduces cooling demand but increases heating demand. Whether the total impact overall is harmful or beneficial depends on the climate and type of structure. Additionally, a cool roof calculator was used to estimate the impact of solar radiation on roofs. The learning from this study is that the exterior color and the solar absorption coefficient should be chosen based on the climate to positively impact the energy use profile and peak demand.