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Thematische Bibliographien / Transport of particles / Dissertationen

Dissertationen zum Thema „Transport of particles“

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Veröffentlicht am 5. Oktober 2024

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1

Imoto, Yu, und Takashi Odagaki. „Diffusion on diffusing particles“. Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193282.

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We investigate random walk of a particle constrained on cells, where cells behave as a lattice gas on a two dimensional square lattice. By Monte Carlo simulation, we obtain the mean first passage time of the particle as a function of the density and temperature of the lattice gas. We find that the transportation of the particle becomes anomalously slow in a certain range of parameters because of the cross over in dynamics between the low and high density regimes; for low densities the dynamics of cells plays the essential role, and for high densities, the dynamics of the particle plays the dominant role.

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2

Jiang, Wenchao. „Spin dependent transport in ferromagnetic particles“. Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52204.

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Spintronics is an emerging technology that arises from the interplay between spin of the charge carrier and the magnetic property of the materials. The miniaturization of spintronic devices requires a deep understanding of ferromagnetic materials at the nanometer scale. This thesis studies the properties of ferromagnetic particles (2-5nm in diameter) using electron transport measurements. A technique to fabricate nanoparticle devices and incorporate microwave in the electron tunneling measurement of the particles is presented. Repeated microwave pulses can directly excite the magnetization of the particles without heating the electrons. Results of the transport measurements on Co particles will be discussed, which demonstrate that electron tunneling through a ferromagnetic particle can induce magnetization excitations in that particle. A physical model regarding the mesoscopic fluctuations is presented to address the current driven magnetization noise. Numerical simulations based on that model are performed to explain the experimental data and validate the model. Electron transport measurements on Ni, Fe, and Ni??Fe?? are conducted. The hysteretic behaviors of the particles in presence of electron tunneling have strong material dependence, which is mainly due to the magnetic shape anisotropy. Electron tunneling is a main source of magnetization noise, while other sources still need to be identified. Some data we collected from literature will be included in this thesis as an appendix.

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3

Wang, Fujing. „Pressure gradient and particle adhesion in the pneumatic transport of fine particles“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28680.pdf.

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4

Bechinger, Clemens. „Active Brownian motion of asymmetric particles“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179545.

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5

Imoto, Yu, und Takashi Odagaki. „Diffusion on diffusing particles“. Diffusion fundamentals 6 (2007) 11, S. 1-7, 2007. https://ul.qucosa.de/id/qucosa%3A14185.

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We investigate random walk of a particle constrained on cells, where cells behave as a lattice gas on a two dimensional square lattice. By Monte Carlo simulation, we obtain the mean first passage time of the particle as a function of the density and temperature of the lattice gas. We find that the transportation of the particle becomes anomalously slow in a certain range of parameters because of the cross over in dynamics between the low and high density regimes; for low densities the dynamics of cells plays the essential role, and for high densities, the dynamics of the particle plays the dominant role.

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6

Trenkmann, Ines, Daniela Täuber, Michael Bauer, Jörg Schuster, Sangho Bok, Shubhra Gangopadhyay und Christian von Borczyskowski. „Investigations of solid liquid interfaces in ultra-thin liquid films via single particle tracking of silica particles“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191734.

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Single particle tracking with a wide field microscope is used to study the solid liquid interface between the viscous liquid tetrakis(2 ethylhexoxy)-silane and a silicon dioxide surface. Silicon dioxide nanoparticles (5 nm diameter) marked with the fluorescent dye rhodamine 6G are used as probes. The distributions of diffusion coefficients, obtained by mean squared displacements, reveal heterogeneities with at least two underlying diffusion components. Measurements on films with varying film thicknesses show that the slower component is independent of the film thickness, while the faster one increases with the film thickness. Additionally, we could show that the diffusion behavior of the particles cannot be sufficiently described by only two diffusion coefficients.

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7

Trenkmann, Ines, Jörg Schuster, Shubhra Gangopadhyay und Christian von Borczyskowski. „Investigation of solid liquid interface in ultra-thin liquid films via single particle tracking of colloidal particles“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191812.

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8

Schmidt, Frank Dr Ing. „Transport und Abscheidung submikroner Partikel - Transport and deposition of submicron particles“. Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-08022001-085456/.

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In this study transport and deposition of submicron particles in turbulent and laminar flows is investigated theoretically. Beginning with the modelling of transport processes in pipe flows, transport onto surfaces and in industrial gas cleaning systems has been calculated. Deposition of particles takes place due to convective diffusion, sedimentation,thermophoresis and impaction. Although different geometries have been investigated a characteristical deposition behaviour has been found with a deposition minimum for submicron particles with diameters larger than 0.1 mm. Transport of these particles often depends on thermo- or electrophoresis.

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9

Han, Shuxiang. „Chlorocarbon transport out of contaminated soil particles“. Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35993.

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10

Wood, Joseph. „Two phase transport in porous catalyst particles“. Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621176.

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11

Martens, Steffen. „Transport of Brownian particles in confined geometries“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16764.

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Ziel dieser Arbeit ist es die Fick-Jacobs Näherung, welche eine genaue Beschreibung zahlreiche Transporteigenschaften von Brownschen Teilchen in räumlich beschränkten Geometrien liefern kann, auf experimentell vorherrschende Gegebenheiten, z.B., sich stark ändernde Geometrien, komplizierte Kraftfelder, Teilchenausdehnung und endliche viskose Reibung, zu erweitern. Dazu wird zuerst die exakte Lösung für die stationäre Wahrscheinlichkeitsdichte mittels Entwicklung in einem geometrischen Parameter, der die Kanalmodulation misst, berechnet. Die höheren Entwicklungsterme ermöglichen die Berechnung von Korrekturen zu den Transportkoeffizienten für sich stark ändernde Geometrien. Ferner kann die Fick-Jacobs Näherung mittels der Entwicklungsmethode auf beliebige Kraftfelder verallgemeinert werden. Am Beispiel des mikrofluidischen Kanals zeigen wir, dass das Zusammenspiel von externen Kräften (skalare Potentiale) und Strömungen (Vektorpotentiale) zur effizienten Trennung von Objekten, mittels des Effektes des hydrodynamisch induzierten entropischen Einsperrens, genutzt werden kann. Da das effiziente Sortieren nach Größe eine der wichtigsten Ziele in der Grundlagenforschung ist, zeigen wir wie die Teilchenausdehnung in die Fick-Jacobs Näherung integriert werden kann. Abschließend wird der Einfluss der Mediumsviskosität auf den Teilchentransport untersucht. Wenn die Zeitskalen separieren, führt adiabatische Eliminierung auch für endliche Reibung zu einer Fick-Jacobs ähnlichen Beschreibung. Diese ist unweigerlich mit Energiegleichverteilung und mit verschwindender Geschwindigkeitskorrelation verbunden. Numerische Simulationen zeigen, dass diese Beschreibung für moderate bis starke Dämpfung und schwache externe Kräfte akkurat ist. Für starke Kräfte wird die angenommene Energiegleichverteilung infolge von Teilchen-Wand Kollisionen verletzt. Dies führt zu einer nichtlinearen Abhängigkeit der Teilchengeschwindigkeit und des effektiven Diffusionskoeffizienten von der Kraftstärke.
This work intends to show how experimentally relevant issues such as strong channel corrugation, sophisticated external force fields, particle size, and the solvent''s viscosity can be incorporated into the commonly used Fick-Jacobs approach which provides a powerful tool to capture many properties of Brownian particles'' transport in confined geometries. First, we derive exact solutions of the stationary probability distribution in terms of an expansion parameter specifying the channel corrugation. Thereby, the leading order is equivalent to the Fick-Jacobs approach. By means of higher expansion orders, which become significant for strong channel corrugation, we obtain corrections to the key particle transport quantities. Going one step further, we generalize the Fick-Jacobs approach to the most general forces. As an exemplary application, we consider microfluidic devices in which the interplay of conservative forces and pressure-driven flows (vector potentials) offers a unique opportunity to efficiently separate Brownian particles of the same size using the newly discovered effect of hydrodynamically enforced entropic trapping. Since separation and sorting by size is a main challenge in basic research, we demonstrate that within certain limits the analytic expressions for the key transport quantities, derived for point-like particles, can be applied to extended objects, too. Lastly, we study the impact of the solvent''s viscosity on particle transport. If the time scales separate, adiabatic elimination results in an effective description even for finite damping. The possibility of such description is intimately connected with equipartition and vanishing velocity correlation. Numerical simulations show that this approach is accurate for moderate to strong damping and for weak forces. For strong external forces, equipartition may break down due to reflections at the boundaries. This leads to a non-monotonic dependence of the particle mobility on the force strength.

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12

Chaikin, Paul, David Pine, Jeremie Palacci und John Royer. „Diffusion and organization in driven particles systems“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-181684.

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13

Chakrabarty, Ayan, Feng Wang, Jonathan Selinger und Qi-Huo Wei. „Fabrication and Brownian diffusion of boomerang colloidal particles“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185744.

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14

Tarasenko, Alexander, und Lubomir Jastrabik. „Surface diffusion of particles over bivariate trap lattices“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191662.

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We investigate the diffusion of particles on heterogeneous lattices with two kinds of nonequivalent sites. General analytical expressions for the chemical and jump diffusion coefficients have been derived in the case of strong inhomogeneity. We have calculated coverage dependencies of the diffusion coefficients and other necessary thermodynamic quantities for some representative values of the lateral pairwise interaction between the particles. The analytical data have been compared with the numerical data obtained by the kinetic Monte Carlo simulations. Almost perfect agreement between the respective results has been found.

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15

Cichos, Frank. „From hot Brownian motion to self-propelled particles“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-184786.

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16

Schaap, Allison Schaap. „Transport and size-separation of airborne particles in a microchannel for continuous particle monitoring“. Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/30230.

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Microfluidics research and development has emerged as a novel and promising tool for the development of sensors and actuators. However, one area in which microfluidics has been only minimally employed is in the handling of airborne particles, or aerosols. The real-time monitoring of aerosols is important for protecting human health and earth’s environment. The small size of microchannels, coupled with the opportunity to integrate sensing technologies, suggests them as a promising tool for the next generation of aerosol sensors. To that end, this thesis presents a microfluidics-based system for the size-separation of aerosols. Specifically, centrifugal force is exerted on each particle as it travels around a curved microchannel, resulting in the particle occupying a size-dependent lateral position in the channel. The behaviours of aerosols in a microchannel are examined, including the effects of flow focusing, the diffusion of airborne particles in a channel, and the centrifugal and viscous forces exerted on particles in a curved microchannel. Mathematical descriptions and computer simulations of these effects are developed to model these effects. Straight and curved microchannels were fabricated and each of these effects was measured experimentally, and compared to the models. Various combinations of airborne particles between 0.2 µm and 3.2 µm were successfully separated by size. A prototype optical particle detector was built and tested for its suitability as a candidate for integration with the microchannel particle separator. This represents the first approach in which aerosols have been separated by centrifugal forces in a microchannel, and one of very few approaches that have been used for any kind of size-based separation of airborne particles in microchannels. The small footprint and potential for integration offered by microsystem fabrication technology make it a desirable avenue of pursuit for the development of small, portable particulate monitors. The results presented here confirm that this approach to size-separation is a feasible option for a future microsystem based size-selective particulate monitor.

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17

Bechinger, Clemens. „Active Brownian motion of asymmetric particles“. Diffusion fundamentals 20 (2013) 16, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13540.

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18

Trenkmann, Ines, Daniela Täuber, Michael Bauer, Jörg Schuster, Sangho Bok, Shubhra Gangopadhyay und Christian von Borczyskowski. „Investigations of solid liquid interfaces in ultra-thin liquid films via single particle tracking of silica particles“. Diffusion fundamentals 11 (2009) 108, S. 1-12, 2009. https://ul.qucosa.de/id/qucosa%3A14082.

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Single particle tracking with a wide field microscope is used to study the solid liquid interface between the viscous liquid tetrakis(2 ethylhexoxy)-silane and a silicon dioxide surface. Silicon dioxide nanoparticles (5 nm diameter) marked with the fluorescent dye rhodamine 6G are used as probes. The distributions of diffusion coefficients, obtained by mean squared displacements, reveal heterogeneities with at least two underlying diffusion components. Measurements on films with varying film thicknesses show that the slower component is independent of the film thickness, while the faster one increases with the film thickness. Additionally, we could show that the diffusion behavior of the particles cannot be sufficiently described by only two diffusion coefficients.

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19

Trenkmann, Ines, Jörg Schuster, Shubhra Gangopadhyay und Christian von Borczyskowski. „Investigation of solid liquid interface in ultra-thin liquid films via single particle tracking of colloidal particles“. Diffusion fundamentals 11 (2009) 115, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A14089.

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20

Takada, Satoshi. „Studies on transport phenomena of cohesive granular particles“. 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215293.

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21

Laker, Travis S. „Transport of microscopic particles in microchannels and microbubbles“. Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/15816.

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22

Lopes, Felipe Nathan de Oliveira. „Neoclassical transport of particles in magnetic confined plasmas“. reponame:Repositório Institucional da UnB, 2017. http://repositorio.unb.br/handle/10482/24179.

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Dissertação (mestrado)—Universidade de Brasília, Instituto de Física, Programa de Pós-Graduação em Física, 2017.
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Plasmas confinados em diferentes topologias magnéticas são uma tarefa importante na busca pela Energia de Fusão. Hoje em dia, as formas mais estudadas de Fusão Termonuclear Controlada focam em Confinamento Inercial, Stellarators e Tokamaks. No presente trabalho, estudaremos os diferentes mecanismos de transporte presentes nos plasmas toroidalmente confinados. Vamos rever a teoria a partir dos conceitos básicos de transporte de plasma, até as peculiaridades presentes em plasmas toroidalmente confinados, conhecido como tokamak. Na fronteira do modelo de transporte mais realista, a questão do transporte anômalo será tratada com a teoria do transporte turbulento, no âmbito da teoria girocinética. O uso de ferramentas computacionais auxiliará na análise do impacto das microinstabilidades no fluxo de partículas e calor, e auxiliará na validação dessa abordagem, feita com uma análise da literatura
Plasmas confined in several magnetics topologies are an important task in the quest for Fusion Energy. Nowadays, the most studied forms of Controlled Thermonuclear Fusion focus on Inertial Confinement, Stellarators and Tokamaks. In the present work, we are going to study the different transport mechanisms present in toroidally confined plasmas. We are going to review the theory from the basic concepts of plasma transport, until the peculiarities present in toroidally confi- ned plasmas, known as tokamak. In the border of the realistic transport model, the issue of the anomalous transport will be treated with the turbulent transport theory, in the framework of the gyrokinetic theory. The use of computational tools will help us to assist the analysis of microinstabilities impact on flux levels, and to give support in the validation of this approach, done with a thorough analysis the literatures.

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23

Yellen, Benjamin Biron Friedman Gary. „Magnetically programmable transport and assembly of colloidal particles /“. Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/333.

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24

Long, Brian R. „Transport of polymers and particles microfabricated array devices“. Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8289.

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xvi, 127 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
Brownian ratchets generate transport at the micron scale with the help of thermal motion. The Brownian ratchet studied here is the flashing ratchet which transports particles by switching on and off a spatially asymmetric, periodic potential. Experimental work in the literature indicates that interdigitated electrode arrays can been used to create such potentials in solution, but no detailed study of particle trajectories has accompanied such experiments. Here, interdigitated electrode array devices were fabricated. Analysis of the trajectories of individual particles moving in response to a switching voltage revealed that the transport is likely due to electroosmotically driven fluid flow, not the Brownian ratchet effect. Simulation work in the literature predicts that polymers in a ratchet potential will exhibit qualitatively different transport from the particle case. Here, polymer transport was tested experimentally using interdigitated electrode array devices, collecting images of individual Ã Ã Ã Ã Ã Ã Â» DNA molecules and applying a flashing voltage. The DNA was observed to move in response to the applied potential and the resulting images contain DNA trajectories and also information about its conformations and dynamics. Conformations were analyzed using principal components analysis, extracting the normal modes of the variations amongst large sets of polymer images. These results iv show no conformational changes indicative of the polymer ratchet mechanism, despite the polymer motion. This result and detailed analysis of the DNA trajectories, suggest that the observed motion was driven by bulk flow generated through electroosmosis, in agreement with results from experiments using particles in similar devices. Deterministic Lateral Displacement (DLD) uses an array of obstacles in a microfluidic channel to sort micron-scale objects with Ã Ã Ã Ã Ã Â¢ Ã Ã Ã Ã Ã Â¼10nm precision. However, very little work has been done to quantitatively address the role of diffusion in DLD sorting. Here, modeling of transport in DLD arrays has shown that using arrays of obstacles that are small compared to their separation can create sorting that is robust against changes in flow velocity. Also, novel sorting modes were revealed when the model was applied to unconventional array geometries that have not been discussed in the literature.
Adviser: Heiner Linke

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25

Kalay, Ziya, Takahiro K. Fujiwara und Akihiro Kusumi. „Diffusion in a hard-disk fluid with immobile particles“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-182568.

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26

Hansen, Eddy W., und Hans Christian Gran. „Probing pore-structure within porous polymer particles by NMR“. Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194852.

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27

Gerber, Gaétan. „Suspensions of particles interacting with porous matrices : transport, deposition and accumulation“. Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC1036.

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La séparation de produits industriels par filtration, la propagation de polluants dans les sols ou la transmission de micro-organismes au sein de tissus biologiques ont en commun le transport de particules au travers de matériaux poreux (matrices).Les interactions particule-matrice engendrent des phénomènes de dépôts de particules, le plus souvent étudiés par simulations numériques, mesures globales ou via des systèmes modèles réduits (1D ou 2D). Grâce à des milieux poreux adaptés (empilements transparents et aléatoires de sphères) et à des méthodes originales d'observation interne (IRM, microscopie confocale), une visualisation directe des dynamiques de transport et de dépôt est rendue possible à l'échelle locale. En variant successivement la taille des particules (de la dizaine de nanomètres à la dizaine de microns), leurs propriétés d'interaction (électrostatique ou magnétique) et leur forme (de sphères uniques à agrégats), tous les régimes de dépôts sont in fine classifiés selon trois paramètres clés : le confinement des particules (rapport de tailles particule/pore), leur affinité avec la matrice et leur potentiel d'agrégation.Deux exemples illustrent en particulier la diversité des régimes étudiés ; chacun étant associé à un modèle prédictif simple permettant une application directe à un large panel de systèmes. D’une part, le coincement stérique de particules non-colloïdales conduit à la formation d’amas de taille comparable aux pores, déviant l'écoulement. Une concentration critique de ces bouchons correspond à une saturation de la matrice et divergence des dépôts (blocage complet du système). D'autre part, l'adsorption de particules colloïdales aux parois de la matrice est étudiée selon leur mode de transport et potentiel d’agrégation. Leur accumulation est associée à un mécanisme atypique d'autorégulation équilibrant la cohésion entre particules et les forces visqueuses évoluant avec la porosité ; allant jusqu’à empêcher un blocage du système
From the separation of products on industrial filters to the propagation of pollutants in soils or the transmission of micro-organisms in biological tissues, the transport of particles through porous matrices is ubiquitous. Particle-matrix interactions involve crucial deposition mechanisms, often studied by numerical simulations, global measurements or reduced (1D or 2D) systems. By making adapted 3D porous media (transparent random packings of spheres), and taking advantage of original internal observations (MRI, confocal microscopy), we have been able to directly visualize and analyze the whole range of transport and deposition dynamics at the global and local scales. Varying in turns the particles size (tens of nanometers to tens of microns), long-range interactions (electrostatic or magnetic) and shape (from unique spheres to clusters), all deposition regimes are finally mapped according to three key parameters: particle confinement (particle/pore size ratio), particle-surface affinity, and inter-particle aggregation ability.Two examples highlight the diversity of these regimes. First, we show that non-colloidal particles of sufficient size tend to clog pores by accumulating in pore size clusters, which ultimately constitute regions avoided by the flow. A critical cluster concentration (percolation) corresponds to a system saturation, i.e. caking. Further insights on the impact of the particle shape on the clogging dynamics are also proposed. On another side, for non-clogging colloidal particles, we show that particle accumulation is a self-limited mechanism, towards a deposited fraction associated with a balance between the colloidal cohesive energy and the local flow (drag energy varying with evolving porosity).In the end, the classification of the main deposition regimes combined with simple predictive models allows an application of these results to a broad range of systems

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28

Zheng, Feng. „Thermophoretic force measurements of spherical and non-spherical particles /“. Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/9874.

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29

Chaikin, Paul, David Pine, Jeremie Palacci und John Royer. „Diffusion and organization in driven particles systems“. Diffusion fundamentals 20 (2013) 18, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A12531.

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30

Kurzhals, Jan-Magnus, Marcel Dierl und Philipp Maass. „Phase transitions in driven single file diffusion of suspended particles“. Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198347.

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31

Pei, Chunsheng. „Solar Energetic Particle Transport in the Heliosphere“. Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194303.

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The transport of solar energetic particles (SEPs) in the inner heliosphere is a very important issue which can affect our daily life. For example, large SEP events can lead to the failure of power grids, interrupt communications, and may participate in global climate change. The SEPS also can harm humans in space and destroy the instruments on board spacecraft. Studying the transport of SEPs also helps us understand remote regions of space which are not visible to us because there are not enough photons in those places.The interplanetary magnetic field is the medium in which solar energetic particles travel. The Parker Model of the solar wind and its successor, the Weber and Davis model, have been the dominant models of the solar wind and the interplanetary magnetic field since 1960s. In this thesis, I have reviewed these models and applied an important correction to the Weber and Davis model. Various solar wind models and their limitations are presented. Different models can affect the calculation of magnetic field direction at 1~AU by as much as about 30\%.Analysis of the onset of SEP events could be used to infer the release time of solar energetic particles and to differentiate between models of particle acceleration near the Sun. It is demonstrated that because of the nature of the stochastic heliospheric magnetic field, the path length measured along the lineof force can be shorter than that of the nominal Parker spiral. These results help to explain recent observations.A two dimensional model and a fully three dimensional numerical model for the transport of SEPs has been developed based on Parker's transport equation for the first time. ``Reservoir'' phenomenon, which means the inner heliosphere works like a reservoir for SEPs during large SEP events, and multi-spacecraft observation of peak intensities are explained by this numerical model.

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Hormozi, Sarah. „Transport and dispersion of particles in visco-plastic fluids“. Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45002.

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This thesis focuses on development of a model to predict “spreading” of the solids (i.e. proppant) fraction during the fracturing operation. We develop a 1D model that allows us to estimate dispersion of solid particles along a vertical pipe in a fully turbulent flow of a shear thinning yield stress fluid (i.e., visco-plastic fluid), as well as slip relative to the mean flow. In dimensionless form, this results in a quasilinear advection-diffusion equation. Advection by the mean flow, particle settling relative to the mean, in the direction of gravity, turbulent particle dispersivity and Taylor dispersion are the 4 main transport phenomena modelled in the 1D model. We provide a simple analysis of the 1D model, suitable for spreadsheet-type field design purposes, in which we estimate “mixing lengths” due to both settling and dispersion. Secondly, we provide an accurate numerical algorithm for solution of the 1D model and show how pulses of proppant (i.e. slugs) may or may not interact for typical process parameters.

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Mercier, Richard Steven. „The reactive transport of suspended particles : mechanisms and modeling“. Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15232.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 262-272.
by Richard Steven Mercier.
Ph.D.

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Wångby, Emil. „Transport of non-spherical particles in pipeflow with suction“. Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79806.

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The interest of how small non-spherical particles transport behaviour when transported in pipe-flow is of large interest in a variety applications. This kind of theory have been used when studying composite manufacturing and how particles behaves in the human lungs. The main focus is to study the statistical deposition rate in a flow-field with and without capillary action and gravity. Two kind of particle shapes are of main interest which are prolate and oblate spheroids. In this study the method of vector projection is used to track particle orientation instead of the more common methods of Euler-angles or quaternions. The method of tracking the particle motion used is Lagrangian tracking method which solves the equations of motion for the particles individually. When studying particles of nano-scale the importance of the phenomenon called Brownian motion arises. The inclusion if the Brownian motion gives rise to the solving of stochastic differential equations for the particle transport. To solve the resulting equations of transport a MATLAB program was developed to using the numerical Euler-Maruyama scheme. Simulations is done with a large amount of particles with a varying particle size and aspect ratio. The deposition results are compared between the different particles shape and sizes. It is seen that the effect of the Brownian motion on particle deposition rate increases with a smaller particle size. It is also concluded that the Brownian motion is the dominating reason for particle deposition. From comparing particle shape and size it is seen to have a major effect of the particles deposition. Including capillary action or gravity the inclusion doesn't affect particles deposition as much.

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Long, Brian Russell. „Transport of polymers and particles in microfabricated array devices /“. Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/8289.

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Thesis (Ph. D.)--University of Oregon, 2008.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 122-127). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

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Cichos, Frank. „From hot Brownian motion to self-propelled particles“. Diffusion fundamentals 16 (2011) 23, S. 1, 2011. https://ul.qucosa.de/id/qucosa%3A13755.

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37

Chakrabarty, Ayan, Feng Wang, Jonathan Selinger und Qi-Huo Wei. „Fabrication and Brownian diffusion of boomerang colloidal particles“. Diffusion fundamentals 16 (2011) 78, S. 1-2, 2011. https://ul.qucosa.de/id/qucosa%3A13822.

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38

Tarasenko, Alexander, und Lubomir Jastrabik. „Surface diffusion of particles over bivariate trap lattices“. diffusion fundamentals 11 (2009) 103, S. 1-8, 2009. https://ul.qucosa.de/id/qucosa%3A14077.

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We investigate the diffusion of particles on heterogeneous lattices with two kinds of nonequivalent sites. General analytical expressions for the chemical and jump diffusion coefficients have been derived in the case of strong inhomogeneity. We have calculated coverage dependencies of the diffusion coefficients and other necessary thermodynamic quantities for some representative values of the lateral pairwise interaction between the particles. The analytical data have been compared with the numerical data obtained by the kinetic Monte Carlo simulations. Almost perfect agreement between the respective results has been found.

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Heidernätsch, Mario, Michael Bauer, Daniela Täuber, Günter Radons und Christian von Borcyskowski. „An advanced method of tracking temporarily invisible particles in video imaging“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191774.

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40

Hansen, Eddy W., und Hans Christian Gran. „Probing pore-structure within porous polymer particles by NMR“. Diffusion fundamentals 3 (2005) 21, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14312.

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41

Barlow, Janet F. „Turbulent transport of space charge in the atmospheric surface layer“. Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270265.

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42

Cifuentes, Manuel Valiente. „Few quantum particles on one dimensional lattices“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16191.

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Der aktuelle experimentelle Fortschritt bei der Manipulation ultrakalter Atome mit Licht löst gegenwärtig ein großes Interesse an der Physik entarteter Quantengase und der niederenergetischen Streuung weniger Teilchen aus. Insbesondere ist es möglich, nahezu perfekte periodische Potenziale sogenannte optische Gitter, zu generieren. Die Untersuchung des Verhaltens weniger Quantenteilchen in einem eindimensionalen Gitter ist Thema dieser Arbeit. Der Großteil der Ergebnisse ist im Rahmen der tight-binding-Näherung erhalten worden, welche eine exakt numerische oder analytische Behandlung ermöglicht. Für das Zwei-Körper Problem werden theoretische Methoden entwickelt, um stationäre Streuzustände und gebundene Zustände zu berechnen, und diese werden verallgemeinert, um exakte Ergebnisse für beliebige Wechselwirkungen and Teilchenstatistiken zu erhalten. Der Quantentransport von einem und zwei Teilchen wird auch berücksichtigt. Das Problem der Bindung und Streuung dreier identischer Bosonen wird eingehend betrachtet, wobei neuartige Typen von gebundenen Zuständen entdeckt wurden. Schließlich werden andere Gittersysteme studiert, indem Methoden vorgestellt werden, die mit den für das Zwei-Körper Problem entwickelten Methoden eng verwandt sind.
There is currently a great interest in the physics of degenerate quantum gases and low-energy few-body scattering due to the recent experimental advances in manipulation of ultracold atoms by light. In particular, almost perfect periodic potentials, called optical lattices, can be generated. The physics of few quantum particles on a one-dimensional lattice is the topic of this thesis. Most of the results are obtained in the tight-binding approximation, which is amenable to exact numerical or analytical treatment. For the two-body problem, theoretical methods for calculating the stationary scattering and bound states are developed, and are generalized to obtain exact results for arbitrary interactions and particle statistics. Quantum transport of one and two particles is also considered. The problem of binding and scattering of three identical bosons is studied in detail, finding novel types of bound states. Finally, other lattice systems are studied by introducing methods closely connected with the methods developed for the two-body problem.

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Suñé, Simon Marc. „Anomalous transport and diffusion of Brownian particles on disordered landscapes“. Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/400564.

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Brownian motion refers to the random movement that undergo mesosized particles suspended in a simple sol- vent. Einstein’s probabilistic approach to the Brownian motion is founded on the principal that it is on account of the molecular motions of heat; it can be summarized in three postulates: particles do not to interact with each other, the motion is memoryless at long times, and the distribution of displacements possesses at least two lower moments. According to the Einstein’s theory, the displacements of Brownian particles ought to exhibit a Gaussian distribution whose variance is proportional to time through the diffusion coefficient, that involves the temperature and the friction coefficient. May a constant external force be applied, the mean displacement scales linearly with time. This scenario is referred to as normal transport and diffusion. The thesis aims at exploring the deviations of normal transport and diffusion to exhibit Brownian particles in a disordered medium. The method of choice are numerical simulations of the classical Langevin equation, a generalization of Newtonian equations so as to account for the Brownian trajectories. To grasp the influence of the disorder’s attributes on Brownian motion is the main focus of the thesis. Further, the outcome sheds light into the physical foundations of the anomalous transport and diffusion. Complementarily, some refinements are made on the algorithms employed to simulate the stochastic differential equations. First, it is reviewed the Brownian motion in a periodic potential. According to the attained outcome, some hypothesis are conjectured for the subsequent explorations in disordered media: transport anomalies—if any— would be only of subtransport type when the disorder is static, enhanced diffusion and superdiffusion are likely to be reached, and anomalous transport and diffusion regimes might be transient in dynamic landscapes. For overdamped Brownian particles in a disordered static potential, the anomalous regimes are characterized by the time exponents that exhibit the statistical moments of the ensemble of particle trajectories, as well as by the particle displacement distributions and the clouds of particles. This case of study bears out that the length scale of the roughness of the potential is an essential parameter in the understanding of the effect of disorder. Besides, the shape of the particle density histograms and the particle clouds have been proved to be related to the anomalies. The analogous scenario in the underdamped limit leads to the instantaneous velocity distributions, that disclose appealing properties of the system. This case of study proves that the anomalous transport and diffusion regimes occur no matter the damping, yet they come about at higher forces for high friction conditions. Overdamped Brownian motion of particles in random landscapes of moving deformable obstacles is also studied. It is settled an effective set of quantities to portray the transport and diffusion properties. The characteristic time scale constrains the time span of anomalies, and thus the subsequent steady transport and diffusion coefficients. For a given density of obstacles, both trafficking and diffusion are favored by wider and therefore fewer obstacles. To end, a high density of obstacles hinders both transport and dispersion. Algorithms to carry out the numerical simulations are discussed. A novel method to build Gaussian potential landscapes with arbitrary spatial correlation functions and the only requirement of isotropy is developed. It has the particularity that, although it uses the Fourier space, its constraints are in real space. A refreshing architec- ture for simulating random dynamic obstacles is also covered. Finally, two supplementary physical systems are addressed; the physics of particles undergoing changing viscosi- ties and confinement to quasi 2 d layers, and the transport of the motor KIF1A in a two–dimensional ratchet model that mimics a microtubule.
El moviment Brownià és el bellugueig aleatori que efectuen les partícules de tamany micromètric quan estan suspeses en un dissolvent. Segons la formulació d’Einstein, els desplaçaments que efectuen les partícules exhibeixen una distribució Gaussiana de mitjana nul·la i variança proporcional al temps. La constant que relaciona la dispersió del conjunt de desplaçaments i el temps és el coeficient de difusió, que depèn de la temperatura i el coeficient de fricció. Si les partícules estan sotmeses a una força externa, la velocitat mitjana del conjunt és no nul·la, donant lloc al fenòmen del transport. En aquestes condicions, el valor mig de la distribució de desplaçaments presenta un creixement lineal amb el temps. Tanmateix, el seguiment de partícules sotmeses al moviment Brownià en ambients complexos dóna lloc a desviacions—anomalies—en els resultats clàssics del transport i la difusió, és a dir, dependències no lineals de la mitjana i la dispersió respecte el temps. Els ambients en els quals s’observen aquestes anomalies es poden caracteritzar per mitjà de potencials no–lineals que presenten barreres que modifiquen la distribució dels desplaçaments. L’objecte de la tesi és explorar aquestes anomalies del transport i la difusió de partícules Brownianes sotmeses a un potencial desordenat. El mètode emprat és la simulació numèrica de les equacions de Langevin clàssiques, una adaptació de la mecànica de Newton que permet obtenir les trajectòries de les partícules. En concret, la tesi indaga en les causes que motiven l’aparició de les anomalies i la influència que hi tenen les propietats del potencial desordenat, la força externa, la temperatura, el coeficient de fregament—únicament en l’aproximació d’infraesmorteïment—, etc. En paral·lel, s'han desenvolupat noves tècniques numèriques per simular les equacions dinàmiques estocàstiques. La tesi inclou diversos casos d'estudi en funció de les característiques del potencial no–lineal—periòdic, desordenat estàtic, desordenat dinàmic—i de la dissipació de l'energia—règims sobreesmorteït i infraesmorteït—. Així mateix, també es presenten dos treballs d'aplicació del moviment Brownià per modelitzar casos experi- mentals; l'atrapament de partícules en una interfície quasi–plana amb una viscositat canviant, i el transport del motor KIF1A a través d'un microtúbol.

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Holmstedt, Elise. „Modelling Transport of Non-Spherical Particles in Small Channel Flow“. Doctoral thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-60402.

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A model has been developed to predict the movement of oblate and prolate particles on amicro- and nano-scale in laminar channel flow, both for purposes of statistical aggregationand to study motion of single particles. For the purpose of this thesis the model has beenadapted to examine particle deposition patterns in the human lung and the filtration ofparticles during manufacturing of composites, but the possibilities of the model extendto all areas where the particle Stokes and Reynolds numbers are small.To examine the influence the breathing pattern has on the deposition of inhalednano- and micro-fibres deposition rates were compared at different injection points ofthe breathing cycle, where maximum deposition was found when the particles releasedat the beginning of the respiratory cycle while minimum deposition occurred when therelease came at peak inhalation. A comparison between a quasi-steady flow and a cyclicflow was done and it was found that a quasi-steady solution provides a reasonably goodapproximation if the velocity used is a mean of the velocity during the residence time ofthe simulations.A statistical study was done to compare the deposition rates of oblate and prolateparticles of different size and aspect ratio as they travel down narrowing bronchi in asteady, fully developed parabolic flow field. The model shows a clear correlation betweenincreased particle size and increased deposition, it also consistently yielded a higherdeposition rate for oblate particles compared to prolate particles with a similar geometricdiameter. A study of the motion and orientation of single oblate and prolate particleswith large aspect ratio and the same geometric diameter has also been done.In liquid moulding of fibre reinforced composites the resin can be enhanced by nanoandmicro-particles to give the final product additional properties. This is a processthat can be simulated by approximating the gap formed between the fibre bundles to achannel flow with a radially suctioning component caused by the capillary pressure in themicro channels in the bundles. First this flow field is described with a radial componentthat is constant over the length of the channel and compared with a flow purely drivenby an applied pressure gradient without radial forces. Particle size showed a small butstill noticeable influence, particularly for larger particles under the influence of gravity.The second flow field used is time dependent where the flow front in the bundlesand channel mimics that of previous observations. There is initially a period where theflow front in the channel is leading but the radial capillary fluid transport causes thisto retreat and be overtaken by the flow front in the bundles. Particles mixed in theresin will in general travel with a velocity greater than that of the fluid front until theradial velocity component at that point filters the particles by transporting them to thechannel wall. Particle geometry has a smaller impact on the deposition rates in compositemanufacturing than in inhalation since the effect of Brownian forces and gravity are muchsmaller, although there is still some discernible patterns such as a higher deposition ratefor spherical particles during the transport to the flow front.

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Taskin, Ertan M. „CFD simulation of transport and reaction in cylindrical catalyst particles“. Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-081507-135028/.

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Krutyeva, Margarita, Sergey Vasenkov und Jörg Kärger. „Exploring the influence of the surface resistance of nanoporous particles on molecular transport“. Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194330.

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Molecular transport through the nanoporous particles, in particular, zeolite crystallites, is influenced both by intracrystalline diffusion and surface resistance. In comparison to zeolite crystallites with ideal structure, molecular transport in real-world zeolite particles may often be influenced by the surface barriers resulting from various defects at the surface of the crystallite. The potentials of the combined use of the pulsed field gradient NMR and dynamic Monte Carlo simulations for exploration of the surface permeability of nanoporous particles are demonstrated.

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Günther, Katrin, Andreas Bregulla, Martin Bönsch, Frank Cichos und Michael Mertig. „Suppressing rotational diffusion of Janus particles by surface modifications for directed thermophoretic motion“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183685.

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Kurzhals, Jan-Magnus, Marcel Dierl und Philipp Maass. „Phase transitions in driven single file diffusion of suspended particles“. Diffusion fundamentals 24 (2015) 29, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14545.

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Moore, Matthew C. „Bedload transport: the effects of particle shape and an investigation of a wide range of transport rates“. Thesis, Virginia Polytechnic Institute and State University, 1994. http://hdl.handle.net/10919/50107.

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The effects of particle shape on bedload transport and a wide range of bedload transport rates using both bed subsurface and surface layer based approaches are investigated using fractional transport analysis with a similarity approach. Bedload transport data from a stream containing flat, low density shale particles indicates that the reference transport critical shear stress for the median surface grain size is approximately 2 to 3 times higher than those for more spherical particles. This conclusion indicates a lower susceptibility of disc-like particles to initial entrainment and lower transport rates for given flow conditions than more rounded particles. Analysis of a wide range of transport rates verifies that the slope of the log-log bedload transport rate - bed shear stress relation decreases with increasing transport rate and becomes constant at very high transport rates. This result implies that the dependence of the transport rate on grain size decreases with increasing transport rate. Comparison of bed subsurface and surface layer based bedload transport approaches indicates that the two approaches produce similar transport - shear relations and reference shear stress values.
Master of Science
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Petrov, Eugene P., Anastasiia Artemieva, Christoph Herold und Petra Schwille. „Interaction of semiflexible polymers and rod-like colloidal particles with strongly charged lipid membranes“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-182828.

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