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1
Pike, J. « Analysis of dusty shock waves for a mixed dust ». Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385879.
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Birkett, C. M. « Optical and infrared studies of cometary dust ». Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35839.
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In 1968, Finson and Probstein outlined a theory which could be used to analyse cometary dust tails. This theory is applied to a series of P/Halley images, obtained using the UK Schmidt Telescope. The theory is successful and shows that P/Halley underwent a series of major outbursts during early 1986. The duration of the outbursts is approximately 2 days. This value coincides with the 2.2day nuclear rotation period, estimated by other observers. The size of the dust grains varies from submicron to several hundred microns and their calculated orbital parameters indicate that a considerable fraction of the larger grains contibute to the Zodiacal Dust Cloud. A range of CCD and UK Schmidt images reveal dust features in the comae of comets P/Crommelin, P/Giacobini-Zinner and P/Halley. Intensity contours for many images exhibited a "swinging round" effect i.e. for each image there was a systematic change in the photometric axis from the central condensation outwards. This was attributed to radiation pressure effects. Astrometric images of P/Halley show sharp parabolic hoods. These hoods are discussed with reference to near-nuclear dust grain orbits. Preliminary results indicate that the rotation period of Hailey is at least a few days. Mie (1908), developed a method by which the general properties of scattering and emission by dust grains, can be used to model cometary thermal spectra. Such a method is applied to several P/Halley spectra, taken during April, 1986. The results indicate that the dust grains could be composed of both an absorbing (e.g. magnetite) and a dielectric (e.g. silicate) material. The interrelations between decaying comets and Earth-crossing asteroids are discussed. Optical and infrared observations indicate that comet P/Neujmin 1 may be a transitionary object. P/Arend-Rigaux however, is still very active, displaying a large dust coma, with anisotropic emission.
3
Lampshire, Shelby. « Metal Dust Cloud Distribution Characterization Through Image Analysis ». DigitalCommons@CalPoly, 2021. https://digitalcommons.calpoly.edu/theses/2333.
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With the increasing development of metal additive manufacturing technology, the present need for accurate explosivity testing of high density and exotic metal powders is under active research. The accuracy of such tests depends upon the uniformity of the dust dispersion within the testing chambers during ignition. There is a need for further research to understand the dust cloud dispersion process in order to determine the best time for ignition. This study explores a methodology of using high-speed footage and image analysis to characterize the uniformity of a dust cloud temporally that future applications may build upon.
This thesis consisted of the experimental methods used to generate a dust cloud for image acquisition and an in-depth study of processing pixel data in MATLAB to determine points of highest dust cloud uniformity. The image analysis process was applied to the generated footage and the results were assessed through visual means. The analysis was also applied to dust cloud footage generated by Lawrence Livermore National Laboratory on a transparent replica of a modified ANKO 20-L explosivity testing apparatus. The image analysis methodology proved to offer a promising means of determining dust distribution uniformity as it relates to the timing of explosivity ignition.
4
Janugani, Swapna. « Directional analysis and filtering for dust storm detection in NOAA-AVHRR imagery ». To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Ahmadian, Hossein. « Analysis of enzyme dust formation in detergent manufacturing plant ». Thesis, University of Leeds, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515281.
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Fiege, Katherina [Verfasser], et Mario [Akademischer Betreuer] Trieloff. « Compositional Analysis of Interstellar Dust as seen by the Cassini Cosmic Dust Analyzer / Katherina Fiege ; Betreuer : Mario Trieloff ». Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177249359/34.
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Liu, Bing. « Characterisation of Dust Particles Trapped in Silica Aerogels ». Thesis, KTH, Fusionsplasmafysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-38828.
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This thesis involves the study of dust particles trapped in silica aerogel for fusion dust diagnostics purpose. The low velocity impact experiments are done by implanting predefined dust particles into silica aerogel by using a springpiston air gun. The impact experiment results show that the hypervelocity impact model may not suitable for describing the fusion characteristic dust particles. The samples made by impact experiment are analyzed by ion microbeam analysis methods: Rutherford backscattering spectrometry (RBS) and Particle-induced X-ray Emission spectrometry (PIXE). The elements of dust particles are well identified by the X-ray spectra. The X-ray maps clearly show the dust shape. RBS and NRA spectra of an individual particle or a specific region show the depth information of the trapped particles, which is useful for determining the dust velocities. For the interpretation of ion beam analysis result, simulation of dust particles for RBS and NRA are done. The accessible depth for ion beam analysis in silica aerogel can be several hundred micrometers, which is adequate for dust diagnostics.
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Scott, Alan Douglas. « Laboratory formation and analysis of the materials comprising interstellar dust ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22236.pdf.
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Kjellqvist, Jimmy. « Foundation for an analysis of the dust of theNearby Universe ». Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-438508.
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The current cosmological paradigm of an accelerating cosmic expansion issupported by observations of Type Ia supernovae. However, the light emittedby these and other cosmological sources is not only redshifted by cosmicexpansion but will also interact with matter along the light path. Especiallyintergalactic dust can lead to additional reddening and dimming of distantsources due to light scattering or absorption. This yields systematiccontaminations to cosmological measurements. This project builds afoundation and some of the tools that will be used in a master’s thesis withthe aim of analysing the spatial distribution and the properties of this cosmicdust. While previous studies assumed cosmic dust to be homogeneouslydistributed, it is expected to follow the spatial distribution of galaxies fromwhich it was expelled. This project also starts to recreate previous models ofhomogeneous dust models and measurements which will be used the futuremaster’s thesis. An analysis of the methods and tools used, along with some ofthe dust properties, is also made in this project.
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Perry, Chris. « In-situ dust mass distribution measurements from Giotto encounter with comet P/Halley ». Thesis, University of Kent, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278457.
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Goldsmith, M. J. « A study of R Coronae Borealis and RV Tauri stars ». Thesis, Keele University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328254.
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Crook, Jacquelyn C. « Climate analysis and long range forecasting of dust storms in Iraq ». Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://handle.dtic.mil/100.2/ADA501137.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, June 2009.Thesis Advisor(s): Murphree, Tom ; Stone, Rebecca. "June 2009." Description based on title screen as viewed on July 13, 2009. DTIC Identifiers: Climatology, precipitation rate, statistical forecasting, El Nino, La Nina. Author(s) subject terms: Iraq, Climatology, Long Range Forecast, Composite Analysis Forecast (CAF), Dust, Military Operations, Climate; Seasonal Forecast; Shamal; El Nino; La Nina; Precipitation Rate; Statistical Forecast. Includes bibliographical references (p. 59-61). Also available in print.
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Bland, J. « The structure and kinematics of the ionised gas within NGC 5128 (Centaurus A) ». Thesis, University of Sussex, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372721.
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Chastenet, Jérémy. « Analysis of dust emission in nearby galaxies : implications of the modeling assumptions ». Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE011/document.
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Ma thèse s’est concentrée sur les conséquences qu’ont les choix de modélisation de l’émission de la poussière sur ses propriétés déduites dans les galaxies proches.Une première étude a montré que tous les modèles ne reproduisent pas des observations de deux galaxies proches de façon satisfaisante, bien que tous reproduisent l’émission IR de la Voie Lactée. Cela a aussi mis en évidence que la composition de la poussière est différente d’une galaxie à l’autre, et différente de celle de la Voie Lactée. Le choix de l’environnement des grains, à travers la description du champ de rayonnement qui chauffe ces grains, impacte significativement les résultats tels que la masse totale de poussières. Une deuxième étude s’est concentrée sur les biais systématiques dus à l‘emploi de lois empiriques de mélange pour décrire le chauffage de la poussière. J’ai montré que les masses déduites peuvent être sous- ou surestimées, bien que les ajustements aux données apparaissent raisonnables. Les résultats de cette thèse montrent alors qu’il est nécessaire de prendre en compte les choix de modélisation pour déterminer au mieux les propriétés des poussières dans les galaxies prochesMy thesis focused on the implications of dust emission modelisation choices on its derived properties in nearby galaxies. A first approach showed that all models do not fit observations of two nearby galaxies adequately and similarly, although they all managed to fit the Milky Way infrared emission. It also highlighted that the dust composition is not the same between those two galaxies, and also with that of the Milky Way. The choice of the dust grains environment, through the incident radiation field, can significantly impact results like the total dust masses. A second project investigated the systematics errors due to the empirical laws used to describe the radiation field that heats the dust grains. I showed that some parameters can be over- or underestimated, while showing good fits to the observations. These results show that it is important to take into consideration the choices made for modelisation in order to accurately determine dust properties in nearby galaxies
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Belli, Jacob. « Mission Analysis for Pico-Scale Satellite Based Dust Detection in Low Earth Orbits ». Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5764.
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A conceptual dust detection mission, KnightSat III, using pico-scale satellites is analyzed. The purpose of the proposed KnightSat III mission is to aid in the determination of the size, mass, distribution, and number of dust particles in low earth orbits through a low cost and flexible satellite or a formation of satellites equipped with a new dust detector. The analysis of a single satellite mission with an on-board dust detector is described; though this analysis can easily be extended to a formation of pico-scale satellites. Many design aspects of the mission are discussed, including orbit analysis, power management, attitude determination and control, and mass and power budgets. Two of them are emphasized. The first is a new attitude guidance and control method, and the second is the online optimal power scheduling. It is expected that the measurements obtained from this possible future mission will provide insight into the dynamical processes of inner solar system dust, as well as aid in designing proper micro-meteoroid impact mitigation strategies for future man-made spacecraft.M.S.A.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering; Space System Design and Engineering
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Ai, Ning 1978. « Integrated impact analysis of yellow-dust storms : a regional case study in China ». Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/30029.
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Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2003.Includes bibliographical references (leaves 120-126).
The dust storm is a meteorological event that is caused by strong winds and proceeds from arid and semi-arid regions, transporting a thick cloud of fine sediments. In China, the sediments of dust storms mainly come from the desert and thus are called "yellow-dust storms." Although these storms can disrupt socioeconomic activities widely and pose hazards to human health as well as to the ecosystem, no one has made a systematic socioeconomic analysis of yellow-dust storms. I provide an integrated regional socioeconomic framework to quantify the impacts of yellow-dust storms, as a conceptual model and a demonstration of applicable methodologies. I conduct a case study using 2000 Beijing data, mainly applying input-output analysis, dose-response analysis, and a benefit-transfer approach, and test my results with sensitivity analysis. I demonstrate that the economic impacts of yellow-dust storms have reached all sectors of the regional economy, and that their delayed impacts were more significant than the immediate impacts. Further, I clarify the extent of the economic impacts of yellow-dust storms by both backward and forward linkage analyses. On the basis of both quantitative and qualitative analysis results, I discuss the policy implications of yellow-dust control and show that water-resource planning is critical both for the prevention and mitigation of yellow-dust storm problems.
by Ning Ai.
M.C.P.
17
Young, Joshua Michael. « Synthesis, Modification, and Analysis of Silicate Cosmic Dust Analogues Using Ion-Beam Techniques ». Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1707354/.
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Silicates analogous to cosmic dust were synthesized, modified, and analyzed utilizing ion-beam techniques with Rutherford backscattering spectrometry (RBS) and x-ray diffraction (XRD). Silicate dust is a common constituent in interstellar space, with an estimated 50% of dust produced in the stellar winds of M class Asymptotic Giant Branch (AGB) stars. Silicate dust acts as a surface upon which other chemicals may form (water ice for example), increasing significance in the cosmochemistry field, as well as laboratory astrophysics. Silicate formation in the stellar winds of AGB stars was simulated in the laboratory environment. Three sequential ion implantations of Fe-, MgH2-, and O- with thermal annealing were used to synthesize a mixture appropriate to silicate dust in the surface layers of a p-type Si substrate. Post implantation He+ irradiation was shown to preferentially induce crystalline formation in the analogue prior to thermal annealing. This effect is believed to originate in the ion-electron interaction in the Si substrate. The effects of ionization and ion energy loss due to electronic stopping forces is believed to precipitate nucleation in the amorphous media. For annealing temperatures of 1273 K, predominant quartz formation was found in the substrate, whereas lower annealing temperatures of 1000 K formed enstatite without post-implantation He+ irradiation, and olivine with He+ irradiation. Post annealed crystalline phase modification was investigated via x-ray diffraction and elemental compositions were investigated utilizing RBS. Finally, the interdiffusion of Fe and Mg at temperatures of 900-1100 K was investigated with RBS, and activation energies for interdiffusion were extracted for the transition from amorphous to crystalline phase in the silicate analogues. Fe had an interdiffusion energy of 1.8 eV and Mg 1.5eV. The produced analogues have similar properties to those inferred from infrared spectroscopy of the stellar winds of M-class AGB stars with an oxygen-rich outflow. This work established a method of silicate production using ion beam modifications, explored He+ irradiation effects in the annealed structures, and derived interdiffusion activation energies for Fe and Mg in the amorphous structure. Grain sizes were <100 nm with the observed formation of quartz, enstatite, and olivine.
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Lutfullaeva, Anbara. « Wet Electrostatic Precipitator, Increasing the Efficiency of Collecting Dust Particlesthrough Vibrating Precipitator Analysis ». Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1584444404824906.
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Brunngräber, Robert, Sebastian Wolf, Florian Kirchschlager et Steve Ertel. « The influence of dust grain porosity on the analysis of debris disc observations ». OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/623272.
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Debris discs are often modelled assuming compact dust grains, but more and more evidence for the presence of porous grains is found. We aim at quantifying the systematic errors introduced when modelling debris discs composed of porous dust with a disc model assuming spherical, compact grains. We calculate the optical dust properties derived via the fast, but simple effective medium theory. The theoretical lower boundary of the size distribution - the so-called 'blowout size' - is compared in the cases of compact and porous grains. Finally, we simulate observations of hypothetical debris discs with different porosities and feed them into a fitting procedure using only compact grains. The deviations of the results for compact grains from the original model based on porous grains are analysed. We find that the blowout size increases with increasing grain porosity up to a factor of 2. An analytical approximation function for the blowout size as a function of porosity and stellar luminosity is derived. The analysis of the geometrical disc set-up, when constrained by radial profiles, is barely affected by the porosity. However, the determined minimum grain size and the slope of the grain size distribution derived using compact grains are significantly overestimated. Thus, the unexpectedly high ratio of minimum grain size to blowout size found by previous studies using compact grains can be partially described by dust grain porosity, although the effect is not strong enough to completely explain the trend.
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Alina, Dana. « Analysis of the interstellar dust polarized emission with the Planck Satellite Survey data ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30032.
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Cette thèse est dédiée à l'étude de la polarisation de la poussière interstellaire et est principalement basée sur l'analyse des données du satellite Planck. Tout d'abord, nous caractérisons le biais sur les paramètres de polarisation déduits des données. Nous avons mis en évidence que ce biais dépend non seulement du niveau de bruit, mais également de la corrélation entre les bruits sur les paramètres de Stokes. Nous avons développé des méthodes optimisées d'estimation de la fraction de polarisation, de l'angle de polarisation et de la fonction de dispersion de l'angle de polarisation, qui tiennent compte de la forme des matrices de covariance du bruit. Nous avons montré pour la première fois que le comportement du biais sur la fonction de dispersion d'angle est non trivial, et nous avons proposé une méthode pour évaluer la limite supérieure du biais que nous avons appliqué aux données Planck de la bande à 353 GHz. Nous avons étudié la corrélation entre la fraction de polarisation et la fonction de dispersion d'angle, ainsi que la corrélation entre la fraction de polarisation et la densité de colonne de gaz, sur de grandes fractions du ciel. Ceci nous a permis de mettre en évidence que la structure à 3 dimensions du champ magnétique affecte fortement la fraction de polarisation observée. Lorsque la direction du champ magnétique change le long de la ligne de visée ou dans le faisceau du télescope, on observe que la fraction de polarisation diminue. Nous avons comparé ce résultat à des simulations numériques basées sur la MHD magnétohydrodynamique). Une dépendance similaire de la fraction de polarisation avec la géométrie du champ magnétique y est observée. La diminution de la fraction de polarisation avec la densité de colonne était observée dans les nuages moléculaires dans des études précédentes. Nous avons généralisé ce résultat comme étant également caractéristique du milieu diffus à grande échelle. En combinaison avec les résultats des simulations MHD où un comportement similaire est observé, ceci indique que la diminution de la fraction de polarisation est principalement due aux changements de direction du champ magnétique le long de la ligne de visée. Nous avons pour la première fois déterminé la limite inférieure de la fraction de polarisation maximale réelle bservée avec Planck. Cette limite pourrait correspondre au niveau de polarisation intrinsèque de la poussière interstellaire dans les conditions les plus favorables de la géométrie du champ magnétique. De plus, la comparaison entre la polarisation en émission et en extinction nous a permis d'établir le rapport entre la fraction de polarisation dans les domaines sub-millimétrique et visible. Ce résultat apporte une contrainte forte pour de futurs modèles de la poussière interstellaire. Enfin, nous avons effectué une étude préliminaire sur les propriétés en polarisation des associations de coeurs froid détectés avec Planck. Cette analyse statistique nous permet de confirmer la diminution de la fraction de polarisation dans ces milieux, par rapport à l'environnement local à grande échelle. Nous discutons son origine en termes de perte d'efficacité de l'alignement des grains dans ces associations de coeurs densesThis thesis is dedicated to the study of Galactic dust polarization and is mostly based on the analysis of the Planck satellite data. First, we characterize the bias on polarization parameters which are derived from the measurements. We have evidenced that it depends not only on the noise level but also on the noise correlation between the Stokes parameters. We have developed optimized methods to estimate the polarization fraction, angle and angle dispersion function, that take into account the shape of the noise covariance matrices. The peculiarity of the bias on the polarization angle dispersion function is shown for the first time, and a method for the evaluation of the upper limit on the bias is proposed and applied to the Planck 353 GHz data. We study the correlation between the polarization fraction and the polarization angle dispersion function, and also the correlation between the polarization fraction and the gas column density, over large fractions of the sky. As a result, we show that the three-dimensional structure of the magnetic field highly affects the observed polarization fraction. When the magnetic field direction changes along the line of sight or within the telescope beam, the observed polarization decreases. We observe a similar dependance of the polarization fraction with the magnetic field geometry in MHD (magnetohydrodynamics) simulations. We have evidenced the systematic decrease of the polarization fraction with column density, previously observed only in dense molecular clouds, to be general also at large scales and in the diffuse ISM. In combination with the results from MHD simulations, where a similar behavior is observed, this observational fact indicates that the decrease in the polarization fraction is mostly due to the magnetic field tangling along the line of sight. We derive for the first time the lower limit of the maximum polarization fraction observed with Planck, which could correspond to the dust intrinsic polarization fraction when the field geometry is most favorable. In addition, comparing polarization in emission with Planck and in extinction from stars observations, we find a high sub-millimeter to visible polarization fraction ratio, which will be a strong constraint for future dust models. Finally, we have performed a preliminary study on the polarization properties of Galactic cold clumps detected with Planck. This statistical analysis allows us to confirm the existence of a significant drop of the polarization fraction in the clumps, relatively to the local large scale environment. We discuss its origin in terms of efficiency loss of grain alignment in these dense clumps
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Pinilla, P., A. Pohl, S. M. Stammler et T. Birnstiel. « Dust Density Distribution and Imaging Analysis of Different Ice Lines in Protoplanetary Disks ». IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625520.
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Recent high angular resolution observations of protoplanetary disks at different wavelengths have revealed several kinds of structures, including multiple bright and dark rings. Embedded planets are the most used explanation for such structures, but there are alternative models capable of shaping the dust in rings as it has been observed. We assume a disk around a Herbig star and investigate the effect that ice lines have on the dust evolution, following the growth, fragmentation, and dynamics of multiple dust size particles, covering from 1 mu m to 2 m sized objects. We use simplified prescriptions of the fragmentation velocity threshold, which is assumed to change radially at the location of one, two, or three ice lines. We assume changes at the radial location of main volatiles, specifically H2O, CO2, and NH3. Radiative transfer calculations are done using the resulting dust density distributions in order to compare with current multiwavelength observations. We find that the structures in the dust density profiles and radial intensities at different wavelengths strongly depend on the disk viscosity. A clear gap of emission can be formed between ice lines and be surrounded by ring-like structures, in particular between the H2O and CO2 (or CO). The gaps are expected to be shallower and narrower at millimeter emission than at near-infrared, opposite to model predictions of particle trapping. In our models, the total gas surface density is not expected to show strong variations, in contrast to other gap-forming scenarios such as embedded giant planets or radial variations of the disk viscosity.
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Fiedler, Stephanie. « A model-based analysis of meteorological processes important for North African dust emission ». Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7431/.
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Dust aerosol is abundant and important in the Earth system due to its influence on the radiation balance, the hydrological cycle, human health and ecosystems. Reducing the currently large uncertainties in dust effects requires realistic simulations of the lifecycle of dust aerosol which depends on the time, location and amount of dust emission. Emission estimates from models show a large variety, the reduction of which requires a systematic evaluation of dust-emitting winds. Different processes are known, but their relative importance was previously poorly quantified. This work investigates dust-emitting winds in North Africa based on single meteorological processes which helps guiding future model development. Based on 32 years of ERA-Interim data and a dust model, the emission amounts associated with nocturnal low-level jets (NLLJs), atmospheric depressions and mobile, long-lived cyclones are estimated climatologically for the first time. The results highlight NLLJs as an important driver for dust emission, particularly in the Bodélé Depression during winter. Associated maxima in mid-morning emission underline the importance of temporally high-resolved winds for dust modelling. ERA-Interim systematically underestimates NLLJ core wind speeds, likely due to artificially increased mixing in stable boundary layers. Derived emission frequencies over the Bodélé Depression agree well with observations, but differ elsewhere. Atmospheric depressions, often in the form of heat lows and lee depressions, occur frequently and coincide with the majority of dust emission. Few depressions develop into mobile and long-lived cyclones which coincide with particularly intense events. The largest emission fractions associated with cyclones are found in northeast Africa during spring, primarily at day with a small emission reduction by soil moisture. Smaller West African areas show similar fractions, likely associated with nearsurface signatures of African Easterly Waves. Comparing results derived from ERA-Interim against the Earth system model of the UK Met Office shows considerable disagreement in NLLJ core wind speeds and dust emissions. In depth analysis underlines the urgency for model development that improves the synoptic-scale conditions and the stable boundary layer. Such model improvements hold the potential to advance the scientific understanding of dust aerosol in the Earth system.
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Fujita, Koji, et 耕史 藤田. « Effect of dust event timing on glacier runoff : sensitivity analysis for a Tibetan glacier ». Wiley, 2007. http://hdl.handle.net/2237/11362.
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Scaggs, Meredith Lynne. « Development and Implementation of a Standard Methodology for Respirable Coal Mine Dust Characterization with Thermogravimetric Analysis ». Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71817.
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The purpose of this thesis is to examine the potential of a novel method for analysis and characterization of coal mine dust. Respirable dust has long been an industry concern due to the association of overexposure leading to the development occupational lung disease. Recent trends of increased incidence of occupational lung disease in miners, such as silicosis and Coal Workers Pneumoconiosis, has shown there is a need for a greater understanding of the respirable fraction of dust in underground coal mines. This study will examine the development of a comprehensive standard methodology for characterization of respirable dust via thermogravimetric analysis (TGA). This method was verified with laboratory-generated respirable dust samples analogous to those commonly observed in underground coal mines.
Results of this study demonstrate the ability of the novel TGA method to characterize dust efficiently and effectively. Analysis of the dust includes the determination of mass fractions of coal and non-coal, as well as mass fractions of coal, carbonate, and non-carbonate minerals for larger respirable dust samples. Characterization occurs through the removal of dust particulates from the filter and analysis with TGA, which continuously measures change in mass with specific temperature regions associated with chemical changes for specific types of dust particulates. Results obtained from the verification samples reveal that this method can provide powerful information that may help to increase the current understanding of the health risks linked with exposure to certain types of dust, specifically those found in underground coal mines.Master of Science
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Drysdale, Mallory Elizabeth Brennan. « Application of simulated lung fluid analysis to characterize the influence of smelter activity on the respiratory bioaccessibility of nickel-bearing soils in Kalgoorlie, Western Australia ». Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1300.
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Felix, Villar Omar Ignacio. « Metals And Metalloids In Atmospheric Dust : Use Of Lead Isotopic Analysis For Source Apportionment ». Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338751.
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Mining activities generate aerosol in a wide range of sizes. Smelting activities produce mainly fine particles (<1 μm). On the other hand, milling, crushing and refining processes, as well tailings management, are significant sources of coarse particles (>1 μm). The adverse effects of aerosols on human health depend mainly on two key characteristics: size and chemical composition. One of the main objectives of this research is to analyze the size distribution of contaminants in aerosol produced by mining operations. For this purpose, a Micro-Orifice Uniform Deposit Impactor (MOUDI) was utilized. Results from the MOUDI samples show higher concentrations of the toxic elements like lead and arsenic in the fine fraction (<1 μm). Fine particles are more likely to be deposited in the deeper zones of the respiratory system; therefore, they are more dangerous than coarse particles that can be filtered out in the upper respiratory system. Unfortunately, knowing the total concentration of contaminants does not give us enough information to identify the source of contamination. For this reason, lead isotopes have been introduced as fingerprints for source apportionment. Each source of lead has specific isotopic ratios; by knowing these ratios sources can be identified. During this research, lead isotopic ratios were analyzed at different sites and for different aerosol sizes. From these analyses it can be concluded that lead isotopes are a powerful tool to identify sources of lead. Mitigation strategies could be developed if the source of contamination is well defined. Environmental conditions as wind speed, wind direction, relative humidity and precipitation have an important role in the concentration of atmospheric dust. Dry environments with low relative humidity are ideal for the transport of aerosols. Results obtained from this research show the relationship between dust concentrations and meteorological parameters. Dust concentrations are highly correlated with relative humidity and wind speed. With all the data collected on site and the analysis of the meteorological parameters, models can be develop to predict the transport of particles as well as the concentration of contaminants at a specific point. These models were developed and are part of the results shown in this dissertation.
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Anderson, John W. « An analysis of a dust storm impacting Operation Iraqi Freedom, 25-27 March 2003 ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FAnderson.pdf.
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Pinilla, P., L. M. Pérez, S. Andrews, der Marel N. van, Dishoeck E. F. van, S. Ataiee, M. Benisty et al. « A Multi-wavelength Analysis of Dust and Gas in the SR 24S Transition Disk ». IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/624044.
Texte intégralRésumé :
We present new Atacama Large Millimeter/sub-millimeter Array (ALMA) 1.3 mm continuum observations of the SR 24S transition disk with an angular resolution less than or similar to 0'.18 (12 au radius). We perform a multi-wavelength investigation by combining new data with previous ALMA data at 0.45 mm. The visibilities and images of the continuum emission at the two wavelengths are well characterized by a ring-like emission. Visibility modeling finds that the ring-like emission is narrower at longer wavelengths, in good agreement with models of dust-trapping in pressure bumps, although there are complex residuals that suggest potentially asymmetric structures. The 0.45 mm emission has a shallower profile inside the central cavity than the 1.3 mm emission. In addition, we find that the (CO)-C-13 and (CO)-O-18 (J = 2-1) emission peaks at the center of the continuum cavity. We do not detect either continuum or gas emission from the northern companion to this system (SR 24N), which is itself a binary system. The upper limit for the dust disk mass of SR 24N is less than or similar to 0.12 M-circle plus, which gives a disk mass ratio in dust between the two components of M-dust,M-SR 24S/M-dust,M-SR 24N greater than or similar to 840. The current ALMA observations may imply that either planets have already formed in the SR 24N disk or that dust growth to millimeter sizes is inhibited there and that only warm gas, as seen by rovibrational CO emission inside the truncation radii of the binary, is present.
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Dikgale, Neo. « Analysis of barometric pressure temperature and air density on flow rate of gravimetric dust sampling pumps and silica dust monitoring at a South African gold mine ». Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/65868.
Texte intégralRésumé :
The eagerness to overcome workforce health crises in the mining industry continues to be a challenge, undermining health system transformation globally and more specifically in South Africa. Despite policy implementation and interventions towards health system improvements in South Africa’s mining sector, literature does not provide a detailed narrative on accurate analysis and calibration, when barometric pressure, temperature and air density variations occur, during crystalline silica dustmonitoring processes. Incorrect reporting of crystalline silica concentrations may therefore be a contributing factor in unceasing new cases of silicosis and other silica dust related health issues. This study aimed to determine the impact of barometric pressure, air density and temperature on the concentration of respirable dust samples, using personal gravimetric dust sampling instrument. The study further sought to establish the impact these environmental variables may contribute and whether this can be quantified and applied on measurements taken to correct historical measurement results. The following objectives were used to: • Determine the impact of barometric pressure, air density and temperature on the flow rate of various gravimetric dust sampling pumps. • Determine the impact of barometric pressure, air density and temperature on the concentration of respirable dust samples, using dust sampling instruments. • Establish the impact of the environmental variables that may contribute to the differences in the results obtained. • Establish whether the GilAir Plus and Tuff pumps do maintain a constant flow rate at various barometric pressure levels. • Analyse gravimetric data to determine the percentage error, if correction factor needs to be applied. • Analyse the particulate matter collected on the filter media to determine the type and particle sizes of the particulate. When a personal airborne silica dust sampler is used underground, it is subjected to extreme ambient thermal conditions, such as barometric pressure, air density changes, and temperature variations due to changes in the geothermal gradient and the increase in virgin rock temperature. However, these changes are not accounted for, neither are they considered when sampling strategies are employed. The current industry sampling methodologies are applied in a manner that assumes that the airborne particulate sampling device, set at certain flow rate under certain conditions of barometric pressure, air temperature and density on surface, will maintain that flow rate when subjected to different ambient environmental conditions underground. The study found that barometric pressure, air density and temperature changes do affect the GilAir Plus and Tuff gravimetric dust pump’s flow rate and therefore underground conditions need to be considered when gravimetric sampling is conducted. The ability of an individual pump to adjust its flow rate as it encounters variations in barometric pressure, temperature and density is dependent on its age, amongst other factors. The GilAir-3 pumps were the only pumps that indicated an increase in flow rate as barometric pressure increased, unlike the GilAir Plus and Tuff pumps. The implications hereof are that the GilAir Plus and Tuff pumps overcompensate for the changes in environmental conditions. The Tuff and GilAir plus, although at first glance seem to be exaggerating the exposure levels, should they be used as instruments of choice for monitoring dust exposures in industry, it could mean that the results obtained, may demand stricter dust control measures be implemented. Instruments of high accuracy in determining worker exposure to quartz are required. This remains that the primary reason for conducting measurements is not merely for compliance, but rather to improve dust control strategies.Dissertation (MSc)--University of Pretoria, 2017.
School of Health Systems and Public Health (SHSPH)
MSc
Unrestricted
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Engström, Johansson Alexandra. « Using Bulk XRF-Analysis of Chinese Loess to Determine High-Resolution Records of Dust Provenance ». Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-317881.
Texte intégralRésumé :
Understanding the sources of the dust that forms the extensive loess deposits on the Chinese Loess Plateau is crucial for reconstructing atmospheric circulation patterns and dust pathways. Dust sources are however highly debated, mainly due to the low resolution of many records and the often ambiguous nature of geochemical proxies. The widely used concept of elemental ratios as provenance indicators is based on the idea that the relative abundance of immobile elements remains unaffected by chemical weathering, thereby preserving source signals. High-resolution spatial and temporal records of loess composition were determined for two study sites and three lithostratigraphic units using bulk X-ray fluorescence (XRF) analysis, and independently dated using Optically Stimulated (OSL) and post-IR Infrared Stimulated (pIR-IRSL) Luminescence dating. Four elemental ratios were chosen based on element properties of mobility and grain size, linear correlation strength and the existence of lithostratigraphic trends: Ti/Al, Si/Al, K/Al and Fe/Ti. Potential source signals were detected at both sites, at glacial-interglacial transitions as well as within lithostratigraphic units. Source changes detected within lithostratigraphic units show millennial-scale variability, indicating that abrupt shifts in dust provenance are possible. This implies that millennial-scale variability of the East Asian Monsoon may be related to changes in atmospheric dust content.
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Markey, Nola M. « Data gathering dust, an analysis of traditional use studies conducted within Aboriginal communities in British Columbia ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq61586.pdf.
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Murphy, Michael M. « Analysis of Seismic Signatures Generated from Controlled Methane and Coal Dust Explosions in an Underground Mine ». Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29705.
Texte intégralRésumé :
Examination of seismic records during the time interval of the Sago Mine disaster in 2006 revealed a small amplitude signal possibly associated with an event in the mine. Although the epicenter of the signature was located in the vicinity where the explosion occurred, it could not be unequivocally attributed to the explosion. More needs to be understood about the seismicity from mine explosions in order to properly interpret critical seismic information. A seismic monitoring system located at NIOSHâ s Lake Lynn Experimental Mine has monitored nineteen experimental methane and dust based explosions. The objective of the study was to analyze seismic signatures generated by the methane and dust explosions to begin understanding their characteristics at different distances away from the source. The seismic signatures from these different events were analyzed using standard waveform analysis procedures in order to estimate the moment magnitude and radiated seismic energy. The procedures used to analyze the data were conducted using self-produced programs not available with existing commercial software. The signatures of the explosions were found to be extremely complex due a combination of mine geometry and experimental design, both of which could not be controlled for the purposes of the study. Geophones located approximately 600 m (1970 ft) and over from the source collected limited data because of the attenuation of the seismic waves generated by the methane explosion. A combination of the methods used to characterize the seismic signatures allowed for differentiation between experimental designs and the size of the explosion. The factors having the largest impact on the signatures were the mine geometry, size of the methane explosion, construction of the mine seal and location of the mine seal. A relationship was derived to correlate the radiated seismic energy to the size of the explosion. Recommendations were made, based upon the limitations of this study, on methods for better collection of seismic data in the future.Ph. D.
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Dunn, Graham Spencer. « Crystallographic and biochemical analysis of three distinct hydrolases : dermatophagoides pteronyssinus 1(Der p1), momordin and the bacterial carbon-carbon hydrolase, MhpC ». Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340364.
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Hamm, Lee Bradford. « Engineering analysis of fugitive particulate matter emissions from cattle feedyards ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/3240.
Texte intégralRésumé :
An engineering analysis of the fugitive particulate matter emissions from a
feedyard is not simple. The presence of an evening dust peak in concentration
measurements downwind of a feedyard complicates the calculation of an average 24-h
emission flux for the feedyard. The evening dust peak is a recurring event that occurs
during evening hours when particulate matter concentration measurements increase and
decrease dramatically during a short period of time. The concentrations measured during
the evening can be up to 8 times the concentrations measured throughout the rest of the
day. There is a perception that these concentration increases are due to increases in cattle
activity as the temperature decreases during the evening. The purpose of Objective 1 of
this research was to quantify the changes in concentrations based on changes in
meteorological conditions and/or cattle activity. Using ISCST3, a Gaussian-based EPAapproved
dispersion model used to predict concentrations downwind of the feedyard , the
results of this work indicate that up to 80% of the increase in concentrations can be
attributed to changes in meteorological conditions (wind speed, stability class, and
mixing height.)The total fugitive particulate matter emissions on a cattle feedyard are due to two
sources: unpaved roads (vehicle traffic) and pen surfaces (cattle activity). Objective 2 of
this research was to quantify the mass fraction of the concentration measurements that
was due to unpaved road emissions (vehicle traffic). A recent finding by Wanjura et al.
(2004) reported that as much as 80% of the concentrations measured after a rain event
were due to unpaved road emissions. An engineering analysis of the potential of the
unpaved road emissions versus the total feedyard emissions using ISCST3 suggests that it
is possible for 70 to 80% of the concentration measurements to be attributed to unpaved
road emissions.
The purpose of Objective 3 was to demonstrate the science used by ISCST3 to
predict concentrations downwind of an area source. Results from this study indicate that
the ISCST3 model utilizes a form of the Gaussian line source algorithm to predict
concentrations downwind of an area source.
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Rinaldi, G., U. Fink, L. Doose, G. P. Tozzi, F. Capaccioni, G. Filacchione, D. Bockelée-Morvan et al. « Properties of the dust in the coma of 67P/Churyumov-Gerasimenko observed with VIRTIS- M ». OXFORD UNIV PRESS, 2016. http://hdl.handle.net/10150/624747.
Texte intégralRésumé :
An investigation is presented of the dust scattering in the coma of 67P/Churyumov-Gerasimenko for the dates of 2015 February 28, March 15 and April 27. A comparison of the morphology of dust continuum maps at 1.1 mu m and gas emission shows that for the above dates the spatial distribution of the dust is strongly correlated with H2O but not with CO2 emission. For April 27, the radial profile on the illuminated side of the nucleus in the inner coma agrees well with the direct simulation Monte Carlo (DSMC) calculations as the dust is accelerating and flows outwards distribution of the dust is narrower than the broader emission of the gas. Af. values are 1.13 m for 2015 February 28, 2.02 m for April 27, while local values for March 15 are 2.3-5.3 m, depending on the nucleus illumination. In the inner coma, the spectral reflectivity from 0.35 to 3.5 mu m displays a red slope with a change at around 1 mu m. From 0.35 to 0.8 mu m, the values range from 9 to 12 +/- 1 per cent per 100 nm both on the sunlit side and on the dark side. From 1 to 2.5 mu m, the values are 1.7 +/- 0.2 per cent per 100 nm on the sunlit side and 3 +/- 1 per cent per 100 nm on the dark side. For the August 26 jet, no significant increase of the colour gradient with distance from the nucleus could be observed, nor any significant difference detected between the jet and the background coma.
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Åkerlund, Simon. « From Ancients to Dust... : Through Veneration and Condemnation : Exploring of the role of Cultural Heritage and Iconoclasm ». Thesis, Uppsala universitet, Teologiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324589.
Texte intégralRésumé :
This essay attempts to discover a correlation between a perceived veneration of an inherent value of the cultural heritage which is enlightened in the face of the iconoclastic acts of IS (Islamic State). Firstly, the essay establishes how UNESCO could be perceived as a Social System which educates its central binary codes through communication. The codes central to the System are cultural preservation and cultural destruction. Through examining the official documents of the System and analysing their content through Content Analysis, the essay delineates how an inherent value is manifested in cultural heritage. Further it examines whether the System is successful in communicating and implementing its positive binary code into its surrounding environment. The conclusions are that the System aspires to connect what it deems an “outstanding universal value” with an inherent value of democratic human rights. It is also concluded that the System is successful in implementing its positive core binary code into its environment. However, there are indications that this efficiency could dramatically decrease in the future, thereby rendering the System’s value as an ideological standpoint less valuable in the face of theologically motivated iconoclasms.
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Agioutanti, Eleftheria. « An Improved Thermogravimetric Analysis Method for Respirable Coal Mine Dust and Comparison to Results by SEM-EDX ». Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/91984.
Texte intégralRésumé :
It has long been known that chronic exposures to high concentrations of respirable coal mine dust can lead to the development of lung diseases such as Coal Worker's Pneumoconiosis, commonly referred to as "black lung", and silicosis. Since the mid-1990s, an alarming resurgence of diseases has been documented in central Appalachia, where underground mining often necessitates significant extraction of rock strata along with the thin seams of coal. These circumstances have prompted concern over if or how changing dust composition might be a factor in contemporary disease prevalence.
Until now, the total mass concentration and quartz mass fraction of respirable dust have been regulated and monitored in US coal mines. Unfortunately, however, these two metrics alone do not paint a full picture of dust composition. Earlier work in the author's research group established a preliminary thermogravimetric analysis (TGA) method for coal mine dust. The method is intended to allow estimation of three key mass fractions of the dust from separate sources: coal from the coal strata being mined; non-carbonate minerals from the rock strata being mined or drilled; and carbonates that are primarly sourced from application of rock dust products to the mine floor or ribs. However, accuracy of the preliminary method was substantially limited by poor dust recovery from the fibrous filter media used for sample collection.
This thesis includes two studies: The first study aims to establish an improved TGA method. It uses smooth polycarbonate (PC) filters for dust sampling and a modified thermal ramping routine. The method is verified using laboratory-generated respirable dust samples. In the second study, the improved TGA method is used to analyze 75 respirable mine dust samples, collected in 15 US mines. Replicate samples are also analyzed by scanning electron microscopy using energy dispersive X-ray (SEM-EDX). TGA and SEM-EDX results are compared to gain insights regarding the analytical methods and general trends in dust composition within and between mines.Master of Science
It has long been known that chronic exposures to excessive respirable coal mine dust can lead to the development of lung diseases such as Coal Worker’s Pneumoconiosis (“Black Lung”) and silicosis. Disease rates in central Appalachia have shown an alarming and unexpected increase since the mid-1990s, despite declining dust concentrations evident from regulatory compliance monitoring data. Clearly, there is a need to better understand coal mine dust composition, which will require additional analytical methods. Thermogravimetric analysis (TGA) has been proposed as one possible method, because it should allow estimation of three key dust components from separate sources: coal from the coal strata being mined; non-carbonate minerals from the rock strata being mined or drilled; and carbonates from application of rock dust products to the mine floor and ribs. However, preliminary work with TGA showed limited accuracy, mostly due to sampling materials. In this thesis, two studies were performed. The first study aims to establish an improved TGA method using smooth, polycarbonate (PC) filters. The second study demonstrates the method on a large number of mine dust samples, and compares the results to those gained by an alternative method that uses electron microscopy.
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Magwebu, Doris NomaXesibe. « Decisions, translation strategies and process in the translation of Molope's Dancing in the Dust : a critical analysis ». Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/50698.
Texte intégralRésumé :
Thesis (MPhil)--Stellenbosch University, 2007.ENGLISH ABSTRACT: This study has been a long journey to pursue the art and craft involved in a translation process. The indisputably differing natures of the languages at stake have been prominent in the translator's psychological frame throughout the process. The acknowledgement of the differing natures of languages often means knowing exactly what has to be transferred and in which manner it has to be transferred without compromising the demands of any of the languages at stake. The latter also speaks to the preservation of the message of the ST in the TL in the process of transition. The translation of Molope's Dancing in the Dust has given good ground for the exploration of the processes involved in a literary translation. Although the status of Molope's novel in the publishing market appears to be relatively new, there are some good grounds to declare it as fairly translatable. It has been noted in the study that there has been a desire to consult her existing literatures with an intention to evaluate her dominant style of writing, or any of her translated works so that it becomes easier to determine the translatability of this novel. However, this only proved to be an unsuccessful business in the sense that this novel is the first of her works, ever. Nevertheless, it has been stated simultaneously in this study that the expressiveness of Mol ope's novel, especially in rooting out the main events of the 197 6 Soweto Uprisings, ultimately convinced the translator that this art is worthy to be translated. The acknowledgement (by some legends) ofMolope's potential to probe into the main events of the struggle during that era has been another area the translator could rely on. This attempt has been done albeit Molope's sometimes poignant style of writing (much of this has been said in the study), which sought to pose some problematic areas. As has been declared in the hypothesis section, translatability is possible if the process of translation commences on a ST analysis, whereby problematic areas (or areas of interest thereof) are identified with an intention to select a suitable translation strategy. Suffice then to say that an attempt to answer the translatability question of this novel has been made in the chapter of annotation. Assembling a chapter of annotation is itself an attempt to demonstrate the translator's creativity in manoeuvring the ST material in order to produce what she assumes will suit the target readers. The discussion of well-established translation literatures in Chapter 2 serves to give background to the random choice of particular translation strategies at particular points in time. Therefore, the literature which forms Chapter 2 of this study serves to substantiate both what appears in the chapter of annotation and the entire product thereof.
AFRIKAANSE OPSOMMING: Hierdie studie was 'n lang ontdekkingstog na die kuns en vernuf betrokke by die vertaalproses. Die uiteenlopende aard van die tale ter sprake was deurentyd 'n belangrike oorweging vir die vertaler. Die erkenning dat die betrokke tale onteenseglik van mekaar verskil, gaan gewoonlik gepaard met die besef van presies wat op watter wyse oorgedra moet word ten einde aan albei tale reg te laat geskied. Dit behels dus dat die boodskap van die bronteks (BT) in die oordragproses na die teikentaal (TT) behoue bly. Die vertaling van Kagiso Lesego Molope se boek Dancing in the Dust (2004) het as 'n goeie vertrekpunt vir die ontdekking van die letterkundige vertaalproses gedien. Hoewel Molope se roman in die uitgewersmark as betreklik nuut beskou word, kan dit om 'n paar goeie redes as redelik vertaalbaar bestempel word. In die studie het dit duidelik geword dat 'n letterkundige vertaling hetsy vereis dat auteurs se bestaande letterkundige werke geraadpleeg word ten einde hulle oorheersende skryfstyl te bepaal 6f dat enige van hulle reeds vertaalde werke bestudeer word om deur middel van vergelyking die vertaalbaarheid van die tersaaklike werk vas te stel. Aangesien hierdie roman egter Molope se heel eerste werk is, was sodanige vergelykende navorsing nie moontlik nie. Die studie toon nietemin ook aan dat die beeldende aard van Molope se roman, veral met betrekking tot die hoofgebeure van die Soweto-opstand van 1973, die vertaler uiteindelik oortuig het dat die werk 'n vertaling waardig is. Die bevestiging (deur 'n paar legendariese figure) van die potensiaal wat Molope in hierdie ondersoek na die hoofgebeure van die vryheidstryd in daardie era openbaar, was n6g 'n faktor waarop die vertaler kon steun. Die vertaling is dus aangepak ofskoon Molope se uiters aangrypende skryfstyl (waaroor daar heelwat in die studie uitgewei word) 'n paar probleme opgelewer het. Soos in die hipotese genoem, is vertaling slegs moontlik indien die vertaalproses met 'n BT-ontleding afskop waarin (moontlike) probleemareas uitgewys word ten einde 'n toepaslike vertaalstrategie te kies. Dit is dus voldoende om te se dat die annotasiehoofstuk poog om die vraag oor die vertaalbaarheid van hierdie roman te beantwoord. Die saamstel van die annotasiehoofstuk is op sigself 'n paging om te toon hoe die vertaler skeppend met die BT -materiaal omgaan ten einde 'n gepaste teks vir die teikenlesers te skep. Die bespreking van gesaghebbende, betroubare vertaalliteratuur in hoofstuk 2 dien as agtergrond vir die ewekansige keuse van bepaalde vertaalstrategiee op bepaalde tydstippe. Daarom dien die literatuur in hoofstuk 2 as stawing van die inhoud van die annotasiehoofstuk sowel as die eindproduk van die studie.
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Albin, Thomas [Verfasser], et Ralf [Akademischer Betreuer] Srama. « Machine learning and Monte Carlo based data analysis methods in cosmic dust research / Thomas Albin ; Betreuer : Ralf Srama ». Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2019. http://d-nb.info/1191182770/34.
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Engelstaedter, Sebastian. « An analysis of the role of the atmosphere in modulating desert dust variability : controls on emission and atmospheric transport ». Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443725.
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Ridley, J. K. « Examination of the application of space-borne time-of-flight mass spectrometry to the analysis of cosmic dust particles ». Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377578.
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Gonzales, Howell B. « Cattle feedlot dust – laser diffraction analysis of size distribution and estimation of emissions from unpaved roads and wind erosion ». Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/7041.
Texte intégralRésumé :
Master of ScienceDepartment of Biological & Agricultural Engineering
Ronaldo G. Maghirang
Large cattle feedlots emit considerable amounts of particulate matter (PM), including TSP (total suspended particulates), PM[subscript]10 (PM with equivalent aerodynamic diameter of 10 μm or less), and PM[subscript]2.5 (PM with equivalent aerodynamic diameter of 2.5 μm or less). Particulate emissions result from pen surface disturbance by cattle hoof action, vehicle traffic on unpaved roads and alleyways, and wind erosion. Research is needed to determine concentrations of various size fractions, size distribution, and emission rates from various sources in feedlots. This research was conducted to measure particle size distribution using laser diffraction method and estimate emissions from unpaved roads and wind erosion. Particle size distribution and concentrations of PM[subscript]10 and PM[subscript]2.5 at a commercial cattle feedlot in Kansas (Feedlot 1) were measured over a 2-yr period. The feedlot had a capacity of 30,000 head and total pen area of 50 ha and was equipped with a sprinkler system for dust control. Collocated low-volume samplers for TSP, PM[subscript]10, and PM[subscript]2.5 were used to measure concentrations of TSP, PM[subscript]10, and PM[subscript]2.5 at the upwind and downwind edges of the feedlot. Dust samples that were collected by TSP samplers were analyzed with a laser diffraction analyzer to determine particle size distribution. Particle size distribution at the downwind edge of the feedlot was also measured with micro-orifice uniform deposit impactor (MOUDI). The laser diffraction method and MOUDI did not differ significantly in mean geometric mean diameter (13.7 vs. 13.0 μm) but differed in mean geometric standard deviation (2.9 vs. 2.3). From laser diffraction and TSP data, PM[subscript]10 and PM[subscript]2.5 concentrations were also calculated and were not significantly different from those measured by low-volume PM[subscript]10 and PM[subscript]2.5 samplers (122 vs. 131 μg/m[superscript]3 for PM[subscript]10; 26 vs. 35 μg/m[superscript]3 for PM[subscript]2.5). Both PM[subscript]10 and PM[subscript]2.5 fractions decreased as pen surface moisture contents increased, while the PM[subscript]2.5/PM[subscript]10 ratio did not change much with pen surface moisture content. Published emission models were used to estimate PM[subscript]10 emissions from unpaved roads and wind erosion at Feedlot 1 and another nearby feedlot (Feedlot 2). Feedlot 2 had a capacity of 30,000 head, total pen surface area of 59 ha, and used water trucks for dust control. Estimated PM[subscript]10 emissions from unpaved roads and wind erosion were less than 20% of total PM[subscript]10 emissions obtained from inverse dispersion modeling. Further research is needed to establish the applicability of published emission estimation models for cattle feedlots.
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Petrov, Todor P. « DEVELOPMENT OF INDUSTRY ORIENTED CFD CODE FOR ANALYSIS / DESIGN OF FACE VENTILATION SYSTEMS ». UKnowledge, 2014. http://uknowledge.uky.edu/mng_etds/12.
Texte intégralRésumé :
Two of the main safety and health issues recognized during deep cut coal mining are methane and dust hazards. Advances in continuous miner technology have improved safety and productivity. However, these advances have created some environmental problems, notably more dust and methane being generated at the face during coal extraction.
Results of studies performed in the last three decades concerning the face ventilation for deep cut mining showed very complicated airflow behavior. The specifics of flow patterns developed by the face ventilation systems presents significant challenge for analytical description even for equipment-free entry. Fortunately, there are methods, such as numerical simulations that could be used to provide an engineering solution to the problem. Computational Fluid Dynamics (CFD) codes have been successfully applied during the last decade using the power of Supercomputers. Although significant progress has been made, a benchmark industry oriented CFD code dedicated to face ventilation is still not available.
The goal of this project is to provide the mining industry a software for CFD analysis and design of face ventilation systems. A commercial CFD system SC/Tetra Thermofluid Analysis System with Unstructured Mesh Generator, copyright © Cradle Co, was selected for a development platform. A number of CFD models were developed for the needs of this study including methane release, dust generation, 3D models of commonly used continuous mining machines, scrubbers and water spray systems. The developed models and the used CFD code were successfully validated in the part for methane dilution, using available data from small scale and full scale experiments. The developed models for simulation of dust control systems need to be validated in the future. The developed code automates all necessary steps needed for simulation of face ventilation systems, starting with the construction of a 3D model, generation of the computational mesh, solving and monitoring the calculations, to post-processing and graphical representation of the obtained results. This code shall allow mining engineers to design better and safer face ventilation systems while providing the Mine Safety and Health Administration (MSHA) a tool to check and approve the industry’ proposed ventilation plans.
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土井, 克則, Katsunori DOI, Igor MEN'SHOV, 佳朗 中村 et Yoshiaki NAKAMURA. « 衝撃波流れによって形成される粉塵雲の数値シミュレーション ». 日本機械学会, 2005. http://hdl.handle.net/2237/9089.
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Nanayakkara, Charith Eranga. « Heterogeneous chemistry and photochemistry of atmospherically relevant gases on oxide surfaces ». Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4705.
Texte intégralRésumé :
Metal oxides in the atmosphere emitted from various natural and anthropogenic processes alter the chemical balance of the Earth's atmosphere due to heterogeneous and photochemical processes with atmospheric trace gases. Therefore, understanding the heterogeneous chemistry and heterogeneous photochemistry of atmospheric trace gases on these oxide surfaces has become vital to precisely predict the effect of mineral dust loading on the Earth's atmosphere. Among the various components of mineral dust, light absorbing oxides play a significantly important role during the daytime.
The work reported herein has focused mainly on TiO2 and Α-Fe2O3. These are light adsorbing components found in atmospheric mineral dust. Apart from being a component of mineral dust, TiO2 is heavily used in a number of industrial applications ranging from uses in self-cleaning, water purification to cosmetics. These applications have led to their presence in the atmosphere as anthropogenic dust particles and in contact with the atmosphere as a stationary phase. Iron-containing particles are transferred to the atmosphere mainly from wind and volcanic activities in the form of iron-containing mineral dust and volcanic ash aerosols. Α-Fe2O3 is the most stable iron containing compound found in the Earths' crust which constitutes in significant amounts in mineral dust. The presence of these oxide surfaces in the atmosphere can play a major role in heterogeneous chemistry and photochemistry.
In this dissertation research, transmission FTIR spectroscopy and X-ray photoelectron spectroscopy are used to probe the details of heterogeneous chemistry and photochemistry of CO2, SO2, NO2, HCOOH, and HNO3 on titanium dioxide and hematite surfaces. Adsorption sites, surface speciation and surface species stability have been determined from analysis of FTIR and XPS spectra. Isotope labeling experiments were also carried out in order to obtain mechanistic information about the details of surface hydroxyl group reactivity on these oxide particle surfaces. Furthermore, heterogeneous photochemical reactions of adsorbates from atmospheric trace gas adsorption on TiO2 and Α-Fe2O3 were investigated under the conditions pertinent to troposphere. The role of adsorbed water on the stability of adsorbed species that form as a result of heterogeneous reactions and the effect of relative humidity on photochemistry on these oxide particles surfaces has also been investigated due to its important implications in the atmospheric chemistry of oxide surfaces. The research adds to our overall scientific understanding of the molecular level details of heterogeneous chemistry and photochemistry of light absorbing components in the atmosphere.
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Alexander, Jennifer Mary. « Optical properties of mineral dust aerosol including analysis of particle size, composition, and shape effects, and the impact of physical and chemical processing ». Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1819.
Texte intégralRésumé :
Atmospheric mineral dust has a large impact on the earth’s radiation balance and climate. The radiative effects of mineral dust depend on factors including, particle size, shape, and composition which can all be extremely complex. Mineral dust particles are typically irregular in shape and can include sharp edges, voids, and fine scale surface roughness. Particle shape can also depend on the type of mineral and can vary as a function of particle size. In addition, atmospheric mineral dust is a complex mixture of different minerals as well as other, possibly organic, components that have been mixed in while these particles are suspended in the atmosphere. Aerosol optical properties are investigated in this work, including studies of the effect of particle size, shape, and composition on the infrared (IR) extinction and visible scattering properties in order to achieve more accurate modeling methods.
Studies of particle shape effects on dust optical properties for single component mineral samples of silicate clay and diatomaceous earth are carried out here first. Experimental measurements are modeled using T-matrix theory in a uniform spheroid approximation. Previous efforts to simulate the measured optical properties of silicate clay, using models that assumed particle shape was independent of particle size, have achieved only limited success. However, a model which accounts for a correlation between particle size and shape for the silicate clays offers a large improvement over earlier modeling approaches. Diatomaceous earth is also studied as an example of a single component mineral dust aerosol with extreme particle shapes. A particle shape distribution, determined by fitting the experimental IR extinction data, used as a basis for modeling the visible light scattering properties. While the visible simulations show only modestly good agreement with the scattering data, the fits are generally better than those obtained using more commonly invoked particle shape distributions.
The next goal of this work is to investigate if modeling methods developed in the studies of single mineral components can be generalized to predict the optical properties of more authentic aerosol samples which are complex mixtures of different minerals. Samples of Saharan sand, Iowa loess, and Arizona road dust are used here as test cases. T-matrix based simulations of the authentic samples, using measured particle size distributions, empirical mineralogies, and a priori particle shape models for each mineral component are directly compared with the measured IR extinction spectra and visible scattering profiles. This modeling approach offers a significant improvement over more commonly applied models that ignore variations in particle shape with size or mineralogy and include only a moderate range of shape parameters.
Mineral dust samples processed with organic acids and humic material are also studied in order to explore how the optical properties of dust can change after being aged in the atmosphere. Processed samples include quartz mixed with humic material, and calcite reacted with acetic and oxalic acid. Clear differences in the light scattering properties are observed for all three processed mineral dust samples when compared to the unprocessed mineral dust or organic salt products. These interactions result in both internal and external mixtures depending on the sample. In addition, the presence of these organic materials can alter the mineral dust particle shape. Overall, however, these results demonstrate the need to account for the effects of atmospheric aging of mineral dust on aerosol optical properties.
Particle shape can also affect the aerodynamic properties of mineral dust aerosol. In order to account for these effects, the dynamic shape factor is used to give a measure of particle asphericity. Dynamic shape factors of quartz are measured by mass and mobility selecting particles and measuring their vacuum aerodynamic diameter. From this, dynamic shape factors in both the transition and vacuum regime can be derived. The measured dynamic shape factors of quartz agree quite well with the spheroidal shape distributions derived through studies of the optical properties.
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Ramsuchit, Dhunraj. « Analysis of contributions to the PM10 concentration in a gold mine residential village ». Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/33329.
Texte intégralRésumé :
Main findings
Although the data did not allow the inclusion of non-identified or “unknown” sources,
allocation of the impact at the receptor point to the identified sources proved possible
and useful in comparing individual tailings dams contributions. The No. 4 tailings dam
has been identified as one of the major contributors to PM10 concentration at West
Village. The average PM10 gravimetric concentration recorded at West Village was 18.4
μg/m3 and the concentration with the light scatter method was 15.4 μg/m3. Black carbon
has been identified as significant contributor to overall PM10 mass concentrations with
up to 34% in the winter season. Source appointment from receptor-based measurements has not been previously
conducted at Driefontein Gold Mine. Source apportionment can make a valuable
contribution in attempts to reduce air pollution. At a site where particulate matter is the
predominant pollutant from a variety of potential sources, the contributions from the
individual sources may be difficult to distinguish especially if the sources fall within a
single category type with similar pollutant profiles. It would be useful to ascertain the
individual contributions so that the effectiveness of existing control measures can be
determined and areas where additional controls may be required can be identified. Too
this effect, potential dust sources at and around a gold mine were identified. Samples of
the dust sources were collected and analysed for their elemental compositions and
abundances. A receptor point in a mine village was selected and equipped with an ESampler
PM10 dust monitor as well as an aethalometer, the MicroAeth AE51
(MicroAeth). Monthly receptor samples were collected and analysed for their elemental
concentrations. The elemental compositions of the potential sources and the
concentrations at the receptor were statistically analysed for 12 periods of a month each
to determine the possible contributions to the PM10 concentration at a mine village
(West Village, Driefontein Mine, near Carletonville). Main conclusions
Operational tailings dams can under, certain conditions contribute the major portion of
fallout dust and PM10, even more than dormant tailings dams.Dissertation (MSc)--University of Pretoria, 2013.
gm2014
Chemical Engineering
Unrestricted
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McMillen, John D. « Theoretical characterization of the radiative properties of dust aerosol for the Air Force combat climatology center point analysis intelligence system ». Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FMcMillen.pdf.
Texte intégral
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Chandna, Akshat. « A CFD ANALYSIS OF THE FLOW OF FINE PARTICLES IN A TURBULENT MEDIUM AND CONTROLS FOR DUST IN LONGWALL MINING ». OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1817.
Texte intégralRésumé :
Worker exposure to coal dust in underground mines remains a major health hazard. This research has: 1) Analyzed the wetting characteristics of less than 10 micron dust particles using a novel micro-emulsion technology (MET) at bench scale and prototype scale with emphasis on agglomeration of dust particles, and 2) Simulate airflow and dust dispersion patterns on a longwall mining face using CFD modeling techniques to compare the current and proposed spatial distributions of water sprays around a longwall shearer. With the “Final Dust Rule” adopted by MSHA in 2014 and slated to go into full effect August 16, 2016, this research is a significant contribution to the coal industry. A suitable micro-emulsion containing 0.2% oil and 0.0125% didodecyl-dimethyl-ammonium bromide (DDAB) was identified. For assessing the wettability of coal dusts, a slightly modified version of “Fixed Time Wettability” or FTW (Chugh et al., 2004) was employed. These wettability tests however, did not yeild true wettability using the MET. An analysis for both unwetted and wetted portions of coal dust using particle size distribution curves (PSD) confirmed agglomeration when treated with the emulsion. For the unwetted portion, 96.6% of the particles had sizes greater than 25 μm after treatment with MET. Similar data for wetted dust was 100%. Experiemental studies in a 4 ft x 4ft x 10 ft chamber showed 12-15% improvement in respirable dust when using MET as compared to water alone.. Validated computational fluid dynamics (CFD) models were used to study airflow patterns and the interaction between sprays and airflow for designing both engineering and administrative controls around a longwall face. Two important zones – low air velocity (LAV) and recirculation (RC) – were identified around the model of a longwall face. These zones were located: 1) Behind the headgate drum and 2) Above the shearer chassis. Analysis of a modified geometric configuration of sprays on the shearer chassis showed improved coverage for wetting the dust on the longwall face. Numerical modeling comparisons were made between current spray systems and spray systems proposed by Dr. Y. P. Chugh using the concepts of “Continuous and Discrete Phase Modeling”. Analyses included changes in airflow patterns caused by spray systems and dust dispersion tracks generated from the cutting face. Chugh’s spray system was able to effectively eliminate RC zones existing above the shearer body, thereby minimizing the extent to which coal dust enters the walkway of the longwall face where workers are located. The proposed spray system used concepts of multiple wetting points for dust, air-locks, and venturi to wet the dust and direct the dust-laden air from mine workers. These improvements can be used in longwall mines as engineering controls for meeting new dust control standards.
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Taylor, Allison. « THE REDESIGNED VORTECONE : A MAINTENANCE-FREE WET SCRUBBER DEVICE ». UKnowledge, 2019. https://uknowledge.uky.edu/mng_etds/48.
Texte intégralRésumé :
Dust creates health and safety issues in mining and there are several different ways to reduce the amount of respirable dust created. Dust particles also affect the operation and efficiency of mining equipment. One device currently used to reduce dust in a coal mine is a flooded-bed dust scrubber. These type of scrubbers are found on continuous miners and are designed to capture dust particles close to the cutting head. However, the fibrous screens on the flooded-bed dust scrubber clog easily reducing both production and the quality and quantity of air miners are exposed too. The flooded-bed dust scrubber was designed in the 1980s and has not seen any significant changes since. A Vortecone is a wet scrubber system designed to capture small particles in the air and can easily replace the flooded-bed dust scrubber system on a continuous miner. The Vortecone was initially developed to capture over-sprayed paint particles and due to the capture ability was converted over into the mining industry. The first design of the Vortecone had two outlets and a large pressure drop across the system. The Vortecone was redesigned to have one outlet in order to increase confinement time of particles and thus increase the capture abilities. Using CFD analysis and laboratory testing, the redesigned Vortecone has been proven to have a lower resistance than the original design as well as the currently used convention screens. The Vortecone also proved to have a high capture efficiency at high airflows. This maintenance-free wet scrubber device requires much less maintenance than a conventional screen and thus can be used continually without interrupting production. The Vortecone has been designed so it can easily be mounted onto a continuous miner in place of the currently used scrubbers.