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1
Hosack, Michael G. "Optimization of particle tracking for experiment E683 at Fermi National Laboratory". Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941370.
Testo completoAbstract (sommario):
The subject of this thesis is the improvement of particle tracking through the identification and correction of small systematic errors in particle "hit" locations due to positioning of tracking detectors. These errors call be as large or larger than the statistical spatial resolution of tracking detectors themselves, and therefore must be corrected. The focus is on identification and correction of errors due to rotations and beam axis translations.An algorithm is developed for use with proportional wire chamber and drift chamber detectors in experiment E683 at the Wideband facility of Fermi National Laboratory. In this experiment, high energy (tens of GeV) particles, primarily mesons, were produced when photons with energies of 40-400 GeV struck a metal or liquid target.At the present time, the method and code developed for this thesis has not been applied to real data, although an analysis of its effectiveness as a function of detector resolution has been investigated with Monte-Carlo simulations.Department of Physics and Astronomy
2
Huck, Peter Dearborn. "Particle dynamics in turbulence : from the role of inhomogeneity and anisotropy to collective effects". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN073/document.
Testo completoAbstract (sommario):
La turbulence est connue pour sa capacité à disperser efficacement de la matière, que ce soit des polluantes dans les océans ou du carburant dans les moteurs à combustion. Deux considérations essentielles s’imposent lorsqu’on considère de telles situations. Primo, l’écoulement sous-jacente pourrait avoir une influence non-négligeable sur le comportement des particules. Secundo, la concentration locale de la matière pourrait empêcher le transport ou l’augmenter. Pour répondre à ces deux problématiques distinctes, deux dispositifs expérimentaux ont été étudiés au cours de cette thèse. Un premier dispositif a été mis en place pour étudier l’écoulement de von Kàrmàn, qui consiste en une enceinte fermé avec de l’eau forcé par deux disques en contra-rotation. Cette écoulement est connu pour être très turbulent, inhomogène, et anisotrope. Deux caméras rapides ont facilité le suivi Lagrangien des particules isodenses avec l’eau et petites par rapport aux échelles de la turbulence. Ceci a permis une étude du bilan d’énergie cinétique turbulente qui est directement relié aux propriétés de transport. Des particules plus lourdes que l’eau ont aussi été étudiées et montrent le rôle de l’anisotropie de l’écoulement dans la dispersion des particules inertielles. Un deuxième dispositif, un écoulement de soufflerie ensemencé avec des gouttelettes d’eau micrométriques a permis une étude de l’effet de la concentration locale de l’eau sur la vitesse de chute des gouttelettes grâce à une montage préexistant. Un modèle basé sur des méthodes théorique d'écoulements multiphasiques a été élaboré enfin de prendre en compte les effets collectifs de ces particules sedimentant dans un écoulement turbulent. Les résultats théoriques et expérimentaux mettent en évidence le rôle de la polydispersité et du couplage entre les deux phases dans l’augmentation de la sédimentation des gouttelettesTurbulence is well known for its ability to efficiently disperse matter, whether it be atmospheric pollutants or gasoline in combustion motors. Two considerations are fundamental when considering such situations. First, the underlying flow may have a strong influence of the behavior of the dispersed particles. Second, the local concentration of particles may enhance or impede the transport properties of turbulence. This dissertation addresses these points separately through the experimental study of two different turbulent flows. The first experimental device used is the so-called von K\'arm\'an flow which consists of an enclosed vessel filled with water that is forced by two counter rotating disks creating a strongly inhomogeneous and anisotropic turbulence. Two high-speed cameras permitted the creation a trajectory data base particles that were both isodense and heavier than water but were smaller than the smallest turbulent scales. The trajectories of this data base permitted a study of the turbulent kinetic energy budget which was shown to directly related to the transport properties of the turbulent flow. The heavy particles illustrate the role of flow anisotropy in the dispersive dynamics of particles dominated by effects related to their inertia. The second flow studied was a wind tunnel seeded with micrometer sized water droplets which was used to study the effects of local concentration of the settling velocities of these particles. A model based on theoretical multi-phase methods was developed in order to take into account the role of collective effects on sedimentation in a turbulent flow. The theoretical results emphasize the role of coupling between the underlying flow and the dispersed phase
3
Magnusson, Klas E. G. "Segmentation and tracking of cells and particles in time-lapse microscopy". Doctoral thesis, KTH, Signalbehandling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196911.
Testo completoAbstract (sommario):
In biology, many different kinds of microscopy are used to study cells. There are many different kinds of transmission microscopy, where light is passed through the cells, that can be used without staining or other treatments that can harm the cells. There is also fluorescence microscopy, where fluorescent proteins or dyes are placed in the cells or in parts of the cells, so that they emit light of a specific wavelength when they are illuminated with light of a different wavelength. Many fluorescence microscopes can take images on many different depths in a sample and thereby build a three-dimensional image of the sample. Fluorescence microscopy can also be used to study particles, for example viruses, inside cells. Modern microscopes often have digital cameras or other equipment to take images or record time-lapse video. When biologists perform experiments on cells, they often record image sequences or sequences of three-dimensional volumes to see how the cells behave when they are subjected to different drugs, culture substrates, or other external factors. Previously, the analysis of recorded data has often been done manually, but that is very time-consuming and the results often become subjective and hard to reproduce. Therefore there is a great need for technology for automated analysis of image sequences with cells and particles inside cells. Such technology is needed especially in biological research and drug development. But the technology could also be used clinically, for example to tailor a cancer treatment to an individual patient by evaluating different treatments on cells from a biopsy. This thesis presents algorithms to find cells and particles in images, and to calculate tracks that show how they have moved during an experiment. We have developed a complete system that can find and track cells in all commonly used imaging modalities. We selected and extended a number of existing segmentation algorithms, and thereby created a complete tool to find cell outlines. To link the segmented objects into tracks, we developed a new track linking algorithm. The algorithm adds tracks one by one using dynamic programming, and has many advantages over prior algorithms. Among other things, it is fast, it calculates tracks which are optimal for the entire image sequence, and it can handle situations where multiple cells have been segmented incorrectly as one object. To make it possible to use information about the velocities of the objects in the linking, we developed a method where the positions of the objects are preprocessed using a filter before the linking is performed. This is important for tracking of some particles inside cells and for tracking of cell nuclei in some embryos. We have developed an open source software which contains all tools that are necessary to analyze image sequences with cells or particles. It has tools for segmentation and tracking of objects, optimization of settings, manual correction, and analysis of outlines and tracks. We developed the software together with biologists who used it in their research. The software has already been used for data analysis in a number of biology publications. Our system has also achieved outstanding performance in three international objective comparisons of systems for tracking of cells.Inom biologi används många olika typer av mikroskopi för att studera celler. Det finns många typer av genomlysningsmikroskopi, där ljus passerar genom cellerna, som kan användas utan färgning eller andra åtgärder som riskerar att skada cellerna. Det finns också fluorescensmikroskopi där fluorescerande proteiner eller färger förs in i cellerna eller i delar av cellerna, så att de emitterar ljus av en viss våglängd då de belyses med ljus av en annan våglängd. Många fluorescensmikroskop kan ta bilder på flera olika djup i ett prov och på så sätt bygga upp en tre-dimensionell bild av provet. Fluorescensmikroskopi kan även användas för att studera partiklar, som exempelvis virus, inuti celler. Moderna mikroskop har ofta digitala kameror eller liknande utrustning för att ta bilder och spela in bildsekvenser. När biologer gör experiment på celler spelar de ofta in bildsekvenser eller sekvenser av tre-dimensionella volymer för att se hur cellerna beter sig när de utsätts för olika läkemedel, odlingssubstrat, eller andra yttre faktorer. Tidigare har analysen av inspelad data ofta gjorts manuellt, men detta är mycket tidskrävande och resultaten blir ofta subjektiva och svåra att reproducera. Därför finns det ett stort behov av teknik för automatiserad analys av bildsekvenser med celler och partiklar inuti celler. Sådan teknik behövs framförallt inom biologisk forskning och utveckling av läkemedel. Men tekniken skulle också kunna användas kliniskt, exempelvis för att skräddarsy en cancerbehandling till en enskild patient genom att utvärdera olika behandlingar på celler från en biopsi. I denna avhandling presenteras algoritmer för att hitta celler och partiklar i bilder, och för att beräkna trajektorier som visar hur de har förflyttat sig under ett experiment. Vi har utvecklat ett komplett system som kan hitta och följa celler i alla vanligt förekommande typer av mikroskopi. Vi valde ut och vidareutvecklade ett antal existerande segmenteringsalgoritmer, och skapade på så sätt ett heltäckande verktyg för att hitta cellkonturer. För att länka ihop de segmenterade objekten till trajektorier utvecklade vi en ny länkningsalgoritm. Algoritmen lägger till trajektorier en och en med hjälp av dynamisk programmering, och har många fördelar jämfört med tidigare algoritmer. Bland annat är den snabb, den beräknar trajektorier som är optimala över hela bildsekvensen, och den kan hantera fall då flera celler felaktigt segmenterats som ett objekt. För att kunna använda information om objektens hastighet vid länkningen utvecklade vi en metod där objektens positioner förbehandlas med hjälp av ett filter innan länkningen utförs. Detta är betydelsefullt för följning av vissa partiklar inuti celler och för följning av cellkärnor i vissa embryon. Vi har utvecklat en mjukvara med öppen källkod, som innehåller alla verktyg som krävs för att analysera bildsekvenser med celler eller partiklar. Den har verktyg för segmentering och följning av objekt, optimering av inställningar, manuell korrektion, och analys av konturer och trajektorier. Vi utvecklade mjukvaran i samarbete med biologer som använde den i sin forskning. Mjukvaran har redan använts för dataanalys i ett antal biologiska publikationer. Vårt system har även uppnått enastående resultat i tre internationella objektiva jämförelser av system för följning av celler.
QC 20161125
4
Veerasamy, Saravanan. "Valdiation of BaBar tracking software using lambda hyperon". Thesis, University of Iowa, 2007. http://ir.uiowa.edu/etd/141.
Testo completo
5
Trenkmann, Ines, Daniela Täuber, Michael Bauer, Jörg Schuster, Sangho Bok, Shubhra Gangopadhyay e 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.
Testo completoAbstract (sommario):
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.
6
Trenkmann, Ines, Jörg Schuster, Shubhra Gangopadhyay e 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.
Testo completo
7
Trenkmann, Ines, Daniela Täuber, Michael Bauer, Jörg Schuster, Sangho Bok, Shubhra Gangopadhyay e 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.
Testo completoAbstract (sommario):
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.
8
Trenkmann, Ines, Jörg Schuster, Shubhra Gangopadhyay e 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.
Testo completo
9
Heidernätsch, Mario, Michael Bauer, Daniela Täuber, Günter Radons e 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.
Testo completo
10
Heidernätsch, Mario, Michael Bauer, Daniela Täuber, Günter Radons e Christian von Borcyskowski. "An advanced method of tracking temporarily invisible particles in video imaging". Diffusion fundamentals 11 (2009) 111, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A14085.
Testo completo
11
Elhimer, Medhi. "The dynamics of neutrally buoyant particles in isotropic turbulence : an experimental study". Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0049/document.
Testo completoAbstract (sommario):
Le but de cette étude expérimentale est de caractériser la dynamique de particules solides, à flottabilité nulle, incluse dans un écoulement turbulent isotrope en décroissance libre. Les particules utilisées sont de forme sphérique et ont un diamètre de 4 à 5 fois plus grand que l'échelle spatial de Kolmogorov de l'écoulement. De part leur taille, les particules ont également un nombre de Stokes proche de l'unité. On s'attend alors à ce que ces particules aient une dynamique différente de celle du fluide environnant. Dans cette étude, ont se propose de quantifier les différences de vitesses entre les deux phases à l'aide d'une technique de vélocimétrie simultanéeIn this experimental study, the focus is made on the characterization of the dynamics of solid neutrally buoyant particles embedded in a freely decaying, nearly isotropic turbulence, with a weak mean flow. The particles are spherical with diameters several times larger than the Kolmogorov scale. The study of this flow configuration is still challenging both theoretically and numerically. Due to large particle sizes, the local flow around particles can not be considered as uniform and due to fluid-particle density ratio of around unity, the history and Basset forces cannot be neglected in comparison with the viscous drag force. Particle equation of motion is then fully non-linear, in contrast to the equation for heavy particles with diameters smaller then the Kolmogorov scale, for which only the Stokes drag is considered. In several experimental and numerical studies, the effect of particle size on velocity and acceleration statistics has been investigated (Homann and Bec 2010 ; Qureshi et al. 2008 ; Ouellette et al. 2008 ; Xu and Bodenschatz 2008). In the case of isotropic turbulence, Homann and Bec (2010) show that while the PDF of the particle velocity normalized by the square root of its variance does not vary with particle size, the variance itself is size dependent. A scaling relation for particle velocity variance has been proposed by using the Faxen correction (Gatignol 1983) which takes into account the non uniformity of the fluid flow at the scale of the particle. The aim of our research is to further study the dependence of particle dynamics on particle size. To that purpose, a turbulence generator has been set-up and the resulting turbulence is characterized. Then the flow was seeded with millimeter sized, neutrally-buoyant particles and the velocity of the two phases have been measured simultaneously. Simultaneous measurements of particle and surrounding fluid velocities show that although the global velocity statistics of the two phases have comparable values, the particles may have different local velocity from the velocity of the neighboring fluid
12
Ems, Matthieu. "Emission et visualisation de particules de frein : Application sur un banc de freinage à échelle réduite intégrant des conditions d’écoulement représentatives". Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2025. https://ged.uphf.fr/nuxeo/site/esupversions/b30c690c-13f6-4cc8-a488-d7e5afdbe1e7.
Testo completoAbstract (sommario):
Réduire les émissions de particules, notamment les PM10, les PM2.5 et les ultrafines (<100nm) est devenu un enjeu environnemental et de santé publique. Leur dispersion dans l'environnement proche au cours du freinage à friction est liée, d'une part, aux sollicitations thermomécaniques à l'interface garniture – disque, et d'autre part, à l'encombrement sous véhicule qui va influencer leur trajectoire initiale. Cette thèse fait partie du projet BREAQ visant à réduire l'exposition aux particules fines issues du freinage ferroviaire. Les travaux présentés dans ce mémoire s'intéressent plus particulièrement à relier la production de particules aux paramètres thermomécaniques dans le contact d'un frein à disque et à évaluer leur trajectoire par une technique de visualisation. Un banc d'essai de freinage à échelle réduite est dimensionné de sorte à conserver une équivalence sur la densité de flux thermique dissipée et est intégré dans une soufflerie pour émuler le déplacement d'un train. Les conditions d'écoulement d'air sont combinées à celles de freinages afin d’être représentatives de trajets urbains réels. Les particules de différentes tailles sont quantifiées par des compteurs et spectromètres en temps réel, en fonction des paramètres de freinage et d’écoulement. Les données montrent une influence des conditions tribologiques sur le profil des émissions. Les résultats mettent en évidence des phases d'émission de particules (mise en contact, maintien de l’effort, retrait). Une analyse PIV (Particule Imaging Velocimetry), habituellement utilisée pour calculer le champ de vitesse d’un fluide ensemencé, est adaptée à notre étude pour estimer la dispersion des particules proche du système de freinage. Les champs de vitesse estimés des particules sont en cohérence avec les mesures des compteurs. L’analyse PIV a permis de proposer un indicateur de présence, temporel et spatial des particules émises, au cours des différentes phases d'un freinageReducing particulate emissions, particularly PM10, PM2.5, and ultrafine particles, has become a critical environmental and public health issue. Their dispersion in the nearby environment during friction braking is linked, on one hand, to the thermomechanical stresses at the pad-disc interface, and on the other hand, to the under-vehicle clearance, which affects their initial trajectory. This thesis is part of the BREAQ project, aimed at reducing exposure to fine particles generated by railway braking. The work presented in this dissertation specifically focuses on correlating particle production with thermomechanical parameters in the contact of a disc brake and evaluating their trajectory through visualization techniques. A scaled-down braking test bench was designed to maintain equivalency in dissipated heat flux density and was integrated into a wind tunnel to simulate train movement. Airflow conditions were combined with braking conditions to accurately represent real urban journeys. Particles of various sizes were quantified in real-time using counters and spectrometers, based on braking and airflow parameters. The data show that tribological conditions influence the emission profile. The results highlight phases of particle emission (contact initiation, force maintenance, release). A Particle Imaging Velocimetry (PIV) analysis, usually employed to calculate the velocity field of a seeded fluid, was adapted to estimate the dispersion of particles near the braking system. The estimated particle velocity fields are consistent with counter measurements. The PIV analysis enabled the proposal of a temporal and spatial presence indicator of emitted particles during different braking phases
13
Ricci, Ester. "The passage from microstrip to pixel silicon detectors for tracking particles in space". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/250674.
Testo completoAbstract (sommario):
Tracking particle in space is a crucial instance on a large number of space experiments. Measurements of charged cosmic rays based on spectrometers, observation of γ-rays, study of space weather and many other applications require systems equipped with tracking detectors. The sensitive area of detectors required for tracking spans from cm2 to m2. Silicon microstrip detectors have been the elective technology for tracking particles in space for several decades. Their stability, reliability and low power consumption are supported by years of expertise and provided a vast number of significant results on fundamental physics, reached with different experiments. An example of magnetic spectrometers is AMS-02, operated on International Space Station, and the satellite-borne PAMELA, that measure the charged component of cosmic rays and use tracking planes immersed in a magnetic field produced by permanent magnets to discriminate matter from antimatter. AMS-02 mounts several squared meters of microstrip tracker. The strip technology also has some limits. The spatial resolution depends on the pitch of the strips implanted on silicon buffer, that depends on the capabilities of the facility in charge of device construction. The fabrication sites have to use dedicated infrastructures, making costs relatively higher than in the past. Moreover, it is difficult to reduce the detector thickness below about 150 μm. This thickness impacts on measurements because of multiple scattering and reduces the lower threshold of low energy nuclear experiments. Another problem arises when the detector operates in radiation-dense environment. When the same frame shows multiple hits, the correct reconstruction of each interaction point is subject to degeneracy, due to the ambiguity in associating x− and y−hits in the microstrip sensor. The problem worsens if we consider that microstrips show equivalent charge noise generally up to hundreds of electrons if we take into account all the contributions from readout electronics. The resulting signal-to-noise ratio is generally good, but rarely exceeding 10 for Minimum Ionising Particles (MIP). The migration towards a new technology based on pixel devices is interesting because it solves some of these limitations. In particular, the hit position is uniquely defined by the position of the pixels involved in the event and pixel detectors can be thinned down to about 50 μm, with a potential gain in resolution. This thesis focuses on Monolithic Active Pixel Sensors (MAPS). They have the advantage, with respect to both the microstrip detectors and the other pixel families, of having the first stages of readout (front-end amplification, discrimination, digitisation and zero suppression) included on the sensor substrate. The detectors are realised with standard CMOS technology, the same used by foundries for most of commercial applications. Once the design is defined, the mass production of the devices is possible, and it reduces the cost of the single detector. Other pixel detectors do not provide this advantage since the design of sensors is based on different custom technologies, and after the production, the detector must be bump bonded to a readout chip, an expensive and low-yield technique. MAPS also have some limits. The most critical for the use in space is power consumption. A second relevant problem to face is that most of the devices realised with this technique have a digital readout, that does not allow measurement of dE/dx, important for particle identification. The requirement of space experiments to cover large surfaces with a tracking detector implies that using pixels the number of channels to handle increases. MAPS approach solves this issue by including on the detector a smart readout that passes to the DAQ system only data from pixels interested by the event. The MAPS detectors have been proposed for the first time at the end of the nineties. The technology reached maturity in the last years. The ALICE experiment, first of the four main LHC experiments, have installed MAPS detectors for its Inner Tracker Upgrade. For the upgrade the collaboration designed a new MAPS detector, ALPIDE. It is realised by TowerJazz foundry in 180 nm technology. The pixel pitch is 28 μm. The matrix is composed of 512×1024 pixels, for a total surface of 1.5×3 cm2. Although smaller if compared to microstrip ladders, that can reach several tenths of squared cm, the ALPIDE is one of the largest detector realised with this technology. Among the properties of ALPIDE, one particularly interesting for the space application is low power consumption. In ALICE, the low power consumption is required because of the difficulties of power distribution and cooling of the Inner Tracker. The power density is still one order of magnitude higher than for microstrip, but it starts to be interesting for space applications. In this thesis, we explore the possibility to use ALPIDE to realise the tracker for the second High Energy Particle Detector (HEPD-02), a payload of the second China Seismo-Electromagnetic Satellite (CSES-02). The CSES constellation is devoted to the observation of Earth from space and in particular to the study of ionosphere perturbation that might be related to seismic activity on Earth. We organised the study into two parts. The first is dedicated to the optimisation of the detector for space, dealing with the power consumption reduction, thermal control and space compliance tests, another section is devoted to the study of the ALPIDE response to low energy nuclei. The section devoted to space compliance starts with a description of the strategies for power consumption reduction. Some strategies are applied to the detector (use of low-speed lines, smart clock distribution) and require an optimised design of the full tracker and trigger. The design of the different sub-detectors allows distribution of the clock only to a limited section that has a higher probability of being involved in the event. With this approach, we can keep the power consumption of the full tracker below 10 W, as required by the design limits. High power consumption has a large impact on the temperature control of the device. The ALPIDE has an ideal operative temperature of about 30◦, which must be kept constant on the whole detector. ALICE cools down the detector with a water-based system, a solution not applicable in space, where convection is discouraged. A carbon fibre cold plate, designed to optimise the thermal conduction, is applied to control the temperature. The carbon fibre placement is studied to minimise the thickness of the plate and the impact of inert material on tracking performance. The thesis reports the results of various tests of space compliance made on a modified ALICE tracker module, an engineering model of the HEPD-02 module. It was made of 14 ALPIDE detectors disposed into two columns and glued and wire bonded to a Flexible Printed Circuit (FPC). On the other side, the detectors are glued to a carbon fibre plate. The device has been tested according to the requirements of the Chinese Space Agency for vibrations and in thermal-vacuum. A study of the response of the detector to low energy nuclei has been also carried out. The HEPD-02 detector is devoted to the detection of electrons between 3 and 150 MeV and protons between 30 and 300 MeV. We base the study on measurements, taken with protons and low energy nuclei at different test facilities in Italy, as well as simulations. Measurements have been analysed with different tools and used to build a model of the detector response. The only observable of the detector is the cluster, and in particular on the cluster size, i.e. the number of pixels over the set threshold for each interaction. The analysis characterises the dependence of the cluster dimension on the energy deposited in silicon by the particle. The energy release inside ALPIDE has been evaluated using GEANT4 simulations of the beam tests. The values obtained have been used as an input for the analysis and to initialise the charge diffusion process in the device in a second simulation tool, Synopsis TCAD. The TCAD simulation includes the electrical properties of silicon and reproduces the detector structure and the electrical property of the materials. The simulation results have been used to verify our knowledge of the detector details, evaluated as the capability of the simulation to reproduce the experimental data. The simulation is the base of a tool that I developed to predict the cluster size as a function of a given number of parameters. This tool works after the GEANT4 simulation and provides essential information for the event reconstruction software of the experiment. In conclusion, this work reports on space compliance tests performed on the ALPIDE sensor, demonstrating technology readiness level 7 on the scale of space agencies. The dependence of the observed cluster size on the energy deposit has been fully characterised for highly ionising particles. This parametrisation will be a crucial element of the event reconstruction and particle identification algorithms of the HEPD-02 experiment. Given the energy of the nuclei under consideration, this study contains information useful for applications in proton and hadrotherapy.
14
Ricci, Ester. "The passage from microstrip to pixel silicon detectors for tracking particles in space". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/250674.
Testo completoAbstract (sommario):
Tracking particle in space is a crucial instance on a large number of space experiments. Measurements of charged cosmic rays based on spectrometers, observation of γ-rays, study of space weather and many other applications require systems equipped with tracking detectors. The sensitive area of detectors required for tracking spans from cm2 to m2. Silicon microstrip detectors have been the elective technology for tracking particles in space for several decades. Their stability, reliability and low power consumption are supported by years of expertise and provided a vast number of significant results on fundamental physics, reached with different experiments. An example of magnetic spectrometers is AMS-02, operated on International Space Station, and the satellite-borne PAMELA, that measure the charged component of cosmic rays and use tracking planes immersed in a magnetic field produced by permanent magnets to discriminate matter from antimatter. AMS-02 mounts several squared meters of microstrip tracker. The strip technology also has some limits. The spatial resolution depends on the pitch of the strips implanted on silicon buffer, that depends on the capabilities of the facility in charge of device construction. The fabrication sites have to use dedicated infrastructures, making costs relatively higher than in the past. Moreover, it is difficult to reduce the detector thickness below about 150 μm. This thickness impacts on measurements because of multiple scattering and reduces the lower threshold of low energy nuclear experiments. Another problem arises when the detector operates in radiation-dense environment. When the same frame shows multiple hits, the correct reconstruction of each interaction point is subject to degeneracy, due to the ambiguity in associating x− and y−hits in the microstrip sensor. The problem worsens if we consider that microstrips show equivalent charge noise generally up to hundreds of electrons if we take into account all the contributions from readout electronics. The resulting signal-to-noise ratio is generally good, but rarely exceeding 10 for Minimum Ionising Particles (MIP). The migration towards a new technology based on pixel devices is interesting because it solves some of these limitations. In particular, the hit position is uniquely defined by the position of the pixels involved in the event and pixel detectors can be thinned down to about 50 μm, with a potential gain in resolution. This thesis focuses on Monolithic Active Pixel Sensors (MAPS). They have the advantage, with respect to both the microstrip detectors and the other pixel families, of having the first stages of readout (front-end amplification, discrimination, digitisation and zero suppression) included on the sensor substrate. The detectors are realised with standard CMOS technology, the same used by foundries for most of commercial applications. Once the design is defined, the mass production of the devices is possible, and it reduces the cost of the single detector. Other pixel detectors do not provide this advantage since the design of sensors is based on different custom technologies, and after the production, the detector must be bump bonded to a readout chip, an expensive and low-yield technique. MAPS also have some limits. The most critical for the use in space is power consumption. A second relevant problem to face is that most of the devices realised with this technique have a digital readout, that does not allow measurement of dE/dx, important for particle identification. The requirement of space experiments to cover large surfaces with a tracking detector implies that using pixels the number of channels to handle increases. MAPS approach solves this issue by including on the detector a smart readout that passes to the DAQ system only data from pixels interested by the event. The MAPS detectors have been proposed for the first time at the end of the nineties. The technology reached maturity in the last years. The ALICE experiment, first of the four main LHC experiments, have installed MAPS detectors for its Inner Tracker Upgrade. For the upgrade the collaboration designed a new MAPS detector, ALPIDE. It is realised by TowerJazz foundry in 180 nm technology. The pixel pitch is 28 μm. The matrix is composed of 512×1024 pixels, for a total surface of 1.5×3 cm2. Although smaller if compared to microstrip ladders, that can reach several tenths of squared cm, the ALPIDE is one of the largest detector realised with this technology. Among the properties of ALPIDE, one particularly interesting for the space application is low power consumption. In ALICE, the low power consumption is required because of the difficulties of power distribution and cooling of the Inner Tracker. The power density is still one order of magnitude higher than for microstrip, but it starts to be interesting for space applications. In this thesis, we explore the possibility to use ALPIDE to realise the tracker for the second High Energy Particle Detector (HEPD-02), a payload of the second China Seismo-Electromagnetic Satellite (CSES-02). The CSES constellation is devoted to the observation of Earth from space and in particular to the study of ionosphere perturbation that might be related to seismic activity on Earth. We organised the study into two parts. The first is dedicated to the optimisation of the detector for space, dealing with the power consumption reduction, thermal control and space compliance tests, another section is devoted to the study of the ALPIDE response to low energy nuclei. The section devoted to space compliance starts with a description of the strategies for power consumption reduction. Some strategies are applied to the detector (use of low-speed lines, smart clock distribution) and require an optimised design of the full tracker and trigger. The design of the different sub-detectors allows distribution of the clock only to a limited section that has a higher probability of being involved in the event. With this approach, we can keep the power consumption of the full tracker below 10 W, as required by the design limits. High power consumption has a large impact on the temperature control of the device. The ALPIDE has an ideal operative temperature of about 30◦, which must be kept constant on the whole detector. ALICE cools down the detector with a water-based system, a solution not applicable in space, where convection is discouraged. A carbon fibre cold plate, designed to optimise the thermal conduction, is applied to control the temperature. The carbon fibre placement is studied to minimise the thickness of the plate and the impact of inert material on tracking performance. The thesis reports the results of various tests of space compliance made on a modified ALICE tracker module, an engineering model of the HEPD-02 module. It was made of 14 ALPIDE detectors disposed into two columns and glued and wire bonded to a Flexible Printed Circuit (FPC). On the other side, the detectors are glued to a carbon fibre plate. The device has been tested according to the requirements of the Chinese Space Agency for vibrations and in thermal-vacuum. A study of the response of the detector to low energy nuclei has been also carried out. The HEPD-02 detector is devoted to the detection of electrons between 3 and 150 MeV and protons between 30 and 300 MeV. We base the study on measurements, taken with protons and low energy nuclei at different test facilities in Italy, as well as simulations. Measurements have been analysed with different tools and used to build a model of the detector response. The only observable of the detector is the cluster, and in particular on the cluster size, i.e. the number of pixels over the set threshold for each interaction. The analysis characterises the dependence of the cluster dimension on the energy deposited in silicon by the particle. The energy release inside ALPIDE has been evaluated using GEANT4 simulations of the beam tests. The values obtained have been used as an input for the analysis and to initialise the charge diffusion process in the device in a second simulation tool, Synopsis TCAD. The TCAD simulation includes the electrical properties of silicon and reproduces the detector structure and the electrical property of the materials. The simulation results have been used to verify our knowledge of the detector details, evaluated as the capability of the simulation to reproduce the experimental data. The simulation is the base of a tool that I developed to predict the cluster size as a function of a given number of parameters. This tool works after the GEANT4 simulation and provides essential information for the event reconstruction software of the experiment. In conclusion, this work reports on space compliance tests performed on the ALPIDE sensor, demonstrating technology readiness level 7 on the scale of space agencies. The dependence of the observed cluster size on the energy deposit has been fully characterised for highly ionising particles. This parametrisation will be a crucial element of the event reconstruction and particle identification algorithms of the HEPD-02 experiment. Given the energy of the nuclei under consideration, this study contains information useful for applications in proton and hadrotherapy.
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Cussans, David George. "The optimization of the FADC readout system for the Zeus central tracking detector". Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335649.
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Abbasi, Hoseini Afshin. "Experimental study of turbulent flow with dispersed rod-like particles through optical measurements". Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24956.
Testo completoAbstract (sommario):
The knowledge of the behavior of non-spherical particles suspended in turbulent flows covers a wide range of applications in engineering and science. Dispersed two-phase flows and turbulence are the most challenging subjects in engineering, and when combined it gives rise to more complexities as the result of the inherent stochastic nature of the turbulence of the carrier-phase together with the random distribution of the dispersed phase. Moreover, for anisotropic particles the coupling between the translation and rotation of particle increases the complication. Because of the practical importance of prolate particleladen turbulent flows, the plenty of numerical and experimental works have been conducted to study such suspensions. Numerical approaches have given valuable insight of turbulent suspension flows, although the computation has been only carried out at the macro scale and models, not including flow distortion around the particle, comprise the detail of the flow in the order of a particle size. In addition, the model of the forces imposed on the particle by the fluid and mass point treatment are strictly valid for infinitely small particle having size less than all scales of the fluid turbulence. Fully resolved solution at the scale of the dispersed phase in turbulent flows for high Reynolds number has been recently performed but is still a challenge. On the other hand, the presence of particle as the dispersed phase makes experimental measurements much more complicated than those with single phase as a result of particles interference. The area of considerable difficulty with this type of experiments is the measurement of the fluid-phase velocity remarkably close to the particle surface. Generally, experimental researches have been concentrated on measuring the mean velocity and Reynolds stresses of the carrier-phase, and the mean velocity, fluctuations, orientation and accumulation of the non-spherical particles. Higher-order quantities, including Lagrangian particle velocity correlations, the carrier-phase turbulence modulation, and two-particle and particlefluid velocity correlations are also of interest. It has been found that the rotational and translational movements of the fibershaped particle depend on the nature of carrier-phase field and fiber characteristics such as aspect ratio, fiber Stokes number, fiber Reynolds number, and the ratio of fiber to flow length scale. With the development of PIV (Particle Image Velocimetry) and PTV (Particle Tracking Velocimetry) techniques, it has been appeared that combined PIV/PTV will be the best available choice for the experimental study of dispersed two-phase flows. The purpose of combined PIV/PTV measurement of two-phase systems is simultaneous measurements of fluid and suspended objects, where the PIV measurement of the fluid phase are combined with PTV measurement of the dispersed phase. The objective of this doctoral thesis is to study the behavior of rod-like particles suspended in wall-bounded turbulent flow through simultaneous PIV/PTV measurements of the velocity of the flow field and particle motion. As a representative of rod-like particles, I have employed cellulose acetate fibers with the length to diameter ratio (aspect ratio) larger than one. Here, It has been considered only dilute suspensions with no flocculation; thus fiber-fiber interaction is negligible. The measurements have been conducted within the parallel planes (2D view) illuminated by laser in the streamwise direction in thin film suspension flowing on the water table setup at Linné FLOW Centre, KTH Mechanics Lab. It is shown that this setup is a well-behaved experimental model of half channel flows often used in Direct Numerical Simulation (DNS) investigations. Therefore, the experimental results are comparable to their DNS counterpart where it is convenient. A single camera PIV technique has been used to measure flowing suspension. Therefore, it has been needed to preprocess images using a spatial median filter to separate images of two phases, tracer particles as representative of fluid and fibers suspended. The well-known PIV processing algorithms have been applied to the phase of fluid. I have also introduced a novel algorithm to recognize and match fibers in consecutive images to track fibers and estimate their velocity. It is not feasible to study all relevant aspects of particle-laden turbulent flows in a single study. In this study, I present the statistics of the rotational and translational motion of fiber-like particles and the surrounding fluid velocity. To the author’s knowledge, remarkably little experimental work has been published to date on simultaneous measurement of fiber motion and turbulence field in a turbulent fiber suspension flow to reveal dynamics of fibers in this regime. Therefore, the results of this work will be profitable in better understanding of such multiphase flows. The statistical analysis of the translational motion of fibers shows that the size of fiber is a significant factor for the dynamical behavior of the fiber near the wall. It has been observed that, in the region near the wall, the probability of presence of the long fibers is high in both the high-speed and low-speed streaks of flow, and the mean velocity of fibers almost conforms to the mean velocity of flow; whereas the short fibers are mostly present in the low-speed areas, and the fiber mean velocity obey the dominant flow velocity in these areas. In the far-wall regions, the translation of fibers is practically unaffected by the aspect ratio, whereas it depends crucially on the wall-normal distance. Moreover, it was found that in the case of long fibers near the wall, the low speed fibers mostly are orientated in streamwise direction. On the other hand, there is no preferential orientation for fast long fibers. Although wall-normal velocities were not measured in this study, it is hypothesized that this behavior is a result of fibers being affected by the sweep and ejection events known to occur in wall-bounded turbulent flow. The fast fibers are in sweep environment and comes from the upper layer. The low speed fibers are into ejection areas in the vicinity of the wall, and the wall has a stabilizing effect on them. The short fibers are still oriented mostly in streamwise direction for a certain range of low velocity. Furthermore, since a considerable change of the fiber behavior is observed in a certain ratio of the fiber length to the fiber distance from the solid wall, it is supposed that this ratio is also a prominent parameter for the behavior of fiber near the wall. The results presented are in terms of viscous wall units wherever are denoted by superscript “+”.
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Godinez, William J. [Verfasser], e Karl [Akademischer Betreuer] Rohr. "Probabilistic Tracking and Behavior Identification of Fluorescent Particles / William J. Godinez ; Betreuer: Karl Rohr". Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177381591/34.
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Liu, Cong. "New technique for radiolabelling tracer with 64CU for positron emission particles tracking (PEPT) experiments". Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/13709.
Testo completoAbstract (sommario):
Positron emission particle tracking (PEPT) is a non-invasive technique for studying the flow of particulate systems within industrial equipment. The technique tracks a tracer particle labelled with a positron emitting radionuclide moving within the field-of-view of a positron emission tomography (PET) scanner. Two important components of the technique are a PET camera and PEPT tracers, which are particle tracers labelled with a positron emitting radionuclide. Currently, the majority of PEPT tracers are made with 68Ga or 18F. However, the relatively short half-life of these two radionuclides limits the application of PEPT to a maximum of 3 hours of experimental time. 64Cu is a potential candidate for PEPT tracer fabrication due to its relatively long half-life (12.7 h) which could extend the experimental running time of PEPT experiments to two uninterrupted days. The objective of the research described in this thesis was to develop a technique for radiolabelling tracers with 64Cu, and to test their efficacy in PEPT experiment. The work was conducted at Radionuclide Production Department, iThemba LABS near Cape Town, where high purity 64Cu was obtained by a two stages separation method using ion exchange chromatography.
19
Chen, Li. "Fast pyrolysis of millimetric wood particles between 800°C and 1000°C". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10258.
Testo completoAbstract (sommario):
Ces travaux de thèse s’intègrent au sein du projet Biocarb lancé par le Commissariat à l’Énergie Atomique dont l’objectif est de développer des procédés de production de carburants liquides ou gazeux à partir de gaz de synthèse riche en H2 et CO obtenu par gazéification de la biomasse lignocellulosique. L’objectif de cette étude est d’étudier le comportement de particules de biomasse millimétriques lors de la pyrolyse dans des conditions types de gazéifieurs industriels tels que les réacteurs à lit fluidisé ou à flux entraîné, qui fonctionnent pour des flux de chaleur élevés (105 – 106 W⋅m-2) et pour de hautes températures (>800°C). Tout d’abord, des expériences de pyrolyse sont menées à 800 et 950°C dans un four à chute de laboratoire sur des particules de bois entre 350 et 800 μm. Les résultats montrent que dans les conditions de l’étude, l’augmentation de la taille de la particule augmente seulement la durée de la pyrolyse mais ne modifie pas les rendements ou la composition du solide et du gaz au cours de la pyrolyse. Par ailleurs, des mesures basées sur la technique de PTV (Particle Tracking Velocimetry) sont réalisées à température ambiante pour caractériser la taille et la densité des particules de bois brut et de résidu, et valider une corrélation donnant le coefficient de traînée qui sert à calculer le temps de séjour des particules dans le réacteur. On constate à la fin de la pyrolyse une diminution de la densité comprise entre 70 et 80% ainsi qu’une diminution de la taille des particules entre 25 et 40%. Les résultats montrent également que la vitesse de glissement de la particule et l’évolution de ses propriétés doivent être prises en compte lors du calcul de sa vitesse. Enfin, à partir des résultats expérimentaux, un modèle unidimensionnel à coeur rétrécissant est développé pour décrire le comportement d’une particule de bois lors de sa pyrolyse. Le modèle est capable de prévoir l’évolution du rendement en solide, en gaz total et en goudrons au cours de la pyrolyse ainsi que la vitesse de glissement de la particule et son temps de séjour dans le réacteur.L’analyse de sensibilité du modèle montre que même pour des particules millimétriques, une connaissance précise de la chaleur de réaction associée à la pyrolyse, de la densité du bois et de la conductivité thermique du résidu solide est essentielleThe present work is part of a project of the French energy research centre Commissariat à l’Energie Atomique. The goal of the project is to develop processes of production of gaseous or liquid fuel from synthesis gas obtained by gasification of lignocellulosic biomass. The objective of the present work is to study the pyrolysis behaviour of millimetric biomass particles under the operating conditions encountered in fluidized bed or entrained flow gasifiers, namely high external heat flux (105 – 106 W⋅m-2) and high temperature (> 800°C). First, pyrolysis experiments are conducted at 800 and 950°C in a lab-scale drop tube reactor on wood particles between 350 and 800 μm. The results show that under the explored conditions, the increase of the particle size only increases the time required for pyrolysis but does not affect the product distribution during pyrolysis. Since in the pyrolysis experiments, the particle residence time cannot be directly measured, PTV (Particle Tracking Velocimetry) measurements are performed at room temperature to characterize the evolution of the particle size and density along pyrolysis and to validate a drag coefficient correlation for the particle residence time calculation. The optical measurements show that at the end of pyrolysis there is a decrease of particle density of 70 – 80% and of particle size of 25 – 40%. It is also proven that the particle slip velocity cannot be neglected and that the change of these particle properties must be taken into account for the calculation of the particle slip velocity and residence time. Finally, based on these experimental results, a 1D shrinking-core model is developed that is able to predict the solid/gas/tar yields and the residence time of a single particle along pyrolysis in the drop tube reactor. It is validated on both the pyrolysis and optical experiments. The model sensitivity analysis shows that even for millimetric particles, the accurate knowledge of the heat of pyrolysis, of the wood density and of the char thermal conductivity is essential
20
Morawitz, Peter Paul Otto. "The ZEUS first level tracking trigger and studies of supersymmetry at HERA". Thesis, University of Oxford, 1993. http://ora.ox.ac.uk/objects/uuid:2fbc22dc-a14a-4384-94fa-aeb7d0c79abf.
Testo completoAbstract (sommario):
The HERA accelerator, an electron-proton collider facility based at the DESY laboratory in Hamburg, started delivering luminosity to the ZEUS experiment in May 1992. The short time of 96ns between bunch crossings and the fact that the primary source of detector activity in ZEUS does not come from the e-p interactions of interest but rather from other sources makes a high performance three level trigger system essential to data-taking. We present one part of the ZEUS trigger system, the Central Tracking Detector First Level Trigger (CTD-FLT). The principle of operation and the hardware implementation are discussed at length. A prototype system which was used during the early stages of ZEUS data-taking is described. We detail the principles of the CTD-FLT hardware testing and discuss aspects of the First Level Trigger data from the 1993 running period. During this time the CTD trigger has proved to be an invaluable part of the overall system. The high energies accessible at HERA make it possible to probe a variety of new physics models. The second part of this thesis focuses on one such model - Supersymmetry (SUSY). After an introduction to the model, a search for R-parity violating SUSY in the ZEUS data from the 1992 running period is described. No evidence for such signals has been found and hence we set upper limits on the mass scale of the theory. Finally we present a Monte Carlo study of the potential discovery reach of HERA for R-parity violating SUSY models, and come to the conclusion that HERA is an ideal place to look for such phenomena.
21
Cassidy, Adrian S. "Optimising the central tracking detector readout at ZEUS & measuring the longitudinal structure function at HERA". Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361108.
Testo completo
22
Wilson, Simon Spencer. "An investigation into the semi instrumented ZEUS tracking trigger and a study of leptoquarks at ZEUS". Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239047.
Testo completo
23
Majal, Ghulam. "On the Agglomeration of Particles in Exhaust Gases". Licentiate thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235704.
Testo completoAbstract (sommario):
Particulate emissions from road transportation are known to have an adverse impact on human health as well the environment. As the effects become more palpable, stricter legislation have been proposed by regulating bodies. This puts forward a challenge for the automotive industry to develop after treatment technologies to fulfil the progressively stricter legislation. At present, the most common after-treatment technologies used for particulates are the diesel and gasoline particulate filters. The typical size distribution of the particles is such that the smallest particles in terms of size are in numbers the largest, although they are not influencing the total particle mass significantly. The most recent legislation have included restrictions on the particle number as well as particle mass. In this thesis numerical tools for studying the transport and interaction of particles in an exhaust flow are evaluated. The specific application is particle agglomeration as a mean to reduce the number of particles and manipulate the size distribution. As particles agglomerate the particle number distribution is shifted and larger sized agglomerates of particles are created reducing the number of ultra-fine particles. The particle agglomeration is obtained by forcing sudden acceleration and deceleration of the host gas carrying the particles by variations in the cross sectional areas of the geometry it is passing through. Initially, a simplified one dimensional model is utilized to assess the governing parameters of particle grouping. Grouping here means that the particles form and are transported in groups, thus increasing the probability for agglomeration. The lessons learned from the 1D-model are also used to design the three dimensional geometry: an axisymmetric corrugated pipe. Two different geometries are studied, they both have the same main pipe diameter but different diameter on the corrugations. The purpose is to find the potential onset of flow instabilities and the influence of 3D-effects such as recirculation on the agglomeration. The CFD simulations are performed using DES methodology. First the simulations are run without particles in a non pulsatile flow scenario. Later particles are added to the setup in a one way coupled approach (no particle-particle interaction). The main results were: 1) An additional criterion for grouping to the ones given in previous work on the 1D model is proposed. It is found that grouping is more likely if the combination of the pulse frequency and geometric wavelength is large. Furthermore, smooth pulse forms (modelling the modulation in the flow due to the geometry) yielded more grouping than other more abrupt pulse shapes. However, idealised inlet pulses underestimate the extent of grouping compared to actual engine pulses. 2) For the geometry with larger maximum cross sectional area stronger flow separation was observed along with higher turbulent kinetic energy. 3) Particles were added in the flow field and a reduction in the particle count was observed in the initial simulations for particles going from the first corrugated segment to the last. Natural extensions of the present work would be to consider pulsatile flow scenarios, particle-particle interaction and a polydisperse setup for the particlesQC 20181008
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Milne, Graham. "Optical sorting and manipulation of microscopic particles". Thesis, St Andrews, 2007. http://hdl.handle.net/10023/334.
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Janicki, Andrew Joseph. "ANALYSIS OF PARTICLES THOROUGH THE AORTIC ARCH DURING TRANSCATHETER AORTIC VALVE REPLACEMENT". DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1448.
Testo completoAbstract (sommario):
Ischemia caused by particles becoming dislodged during transcatheter aortic valve replacement (TAVR) is a possible complication of TAVR. The particles that become dislodged can travel out of the aortic valve, into the aortic arch, and then into either the brachiocephalic artery, the left common carotid artery, the left subclavian artery or continue into the descending aorta. If the particles continue into the descending aorta it poses no risk of causing ischemia however if it travels into the other arteries then it increases the possibility of the particle causing an ischemic event. The goal of this study is to determine what parameters cause the particle to enter one artery over another. The parameters analyzed are the particle diameter, the particle density, the blood pressure, and the diameter of the catheter used in the surgery. This was done by creating a finite element model in COMSOL Multiphysics® to track the particles flowing through a scan of an actual aortic arch. It was determined that the particle diameter, particle density, and the blood pressure affect which artery the particles take to exit the aortic arch. However the diameter of the surgical catheter used in a transaortic approach is not statistically significant when determining which artery the particles will exit. The study shows that larger diameter particle would lead to a higher transmissions probability into the brachiocephalic artery, the left common carotid artery, and the left subclavian artery while a smaller diameter particle would have a higher transmission probability for the descending aorta. Averaging all particle diameters, densities and blood pressure found that 54.95 ± 13.66% of the particles released will travel into the cerebral circulatory system.
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Juette, Manuel Friedrich [Verfasser], e Joachim [Akademischer Betreuer] Spatz. "3D Submillisecond tracking microscopy of single fluorescent particles with adaptive optics / Manuel Friedrich Juette ; Betreuer: Joachim Spatz". Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1177147939/34.
Testo completo
27
McFall, Jason Derek. "The performance of the ZEUS first level tracking trigger and a study of diffractive D* production in deep inelastic scattering at HERA". Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364105.
Testo completo
28
George, Simon. "Design of the SDC second level silicon tracking trigger : storage of strange meson production in Deep Inelastic Scattering with ZEUS detector at HERA". Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294961.
Testo completo
29
Lambert, Andrew Ryan. "Regional deposition of particles in an image-based airway model: Cfd simulation and left-right lung ventilation asymmetry". Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/537.
Testo completoAbstract (sommario):
Regional deposition and ventilation of particles by generation, lobe and lung during steady inhalation in a computed tomography (CT) based human airway model are investigated numerically. The airway model consists of a seven-generation human airway tree, with oral cavity, pharynx and larynx. The turbulent flow in the upper respiratory tract is simulated by large-eddy simulation. The flow boundary conditions at the peripheral airways are derived from CT images at two lung volumes to produce physiologically-realistic regional ventilation. Particles with diameter less than 2.5 microns are selected for study because smaller particles tend to penetrate to the more distal parts of the lung. The current generational particle deposition efficiencies agree well with existing measurement data. Generational deposition efficiencies exhibit similar dependence on particle Stokes number regardless of generation, whereas deposition and ventilation efficiencies vary by lobe and lung, depending on airway morphology and airflow ventilation. In particular, regardless of particle size, the left lung receives a greater proportion of the particle bolus as compared to the right lung in spite of greater flow ventilation to the right lung. This observation is supported by the left-right lung asymmetry of particle ventilation observed in medical imaging. It is found that the particle-laden turbulent laryngeal jet flow, coupled with the unique geometrical features of the airway, causes a disproportionate amount of particles to enter the left lung.
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Vignetti, Matteo Maria. "Development of a 3D Silicon Coincidence Avalanche Detector (3D-SiCAD) for charged particle tracking". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI017/document.
Testo completoAbstract (sommario):
L’objectif de cette thèse est de développer un détecteur innovant de particules chargées, dénommé 3D Silicon Coincidence Avalanche Detector (3D-SiCAD), réalisable en technologie silicium CMOS standard avec des techniques d’intégration 3D. Son principe de fonctionnement est basé sur la détection en "coïncidence" entre deux diodes à avalanche en mode "Geiger" alignées verticalement, avec la finalité d’atteindre un niveau de bruit bien inférieur à celui de capteurs à avalanche standards, tout en gardant les avantages liés à l’utilisation de technologies CMOS; notamment la grande variété d’offres technologiques disponibles sur le marché, la possibilité d’intégrer dans un seul circuit un système complexe de détection, la facilité de migrer et mettre à jour le design vers une technologie CMOS plus moderne, et le faible de coût de fabrication. Le détecteur développé dans ce travail se révèle particulièrement adapté au domaine de la physique des particules de haute énergie ainsi qu’à la physique médicale - hadron thérapie, où des performances exigeantes sont demandées en termes de résistance aux rayonnements ionisants, "material budget", vitesse, bruit et résolution spatiale. Dans ce travail, un prototype a été conçu et fabriqué en technologie HV-CMOS 0,35µm, en utilisant un assemblage 3D de type "flip-chip" avec pour finalité de démontrer la faisabilité d’un tel détecteur. La caractérisation du prototype a finalement montré que le dispositif développé permet de détecter des particules chargées avec une excellente efficacité de détection, et que le mode "coïncidence" réduit considérablement le niveau de bruit. Ces résultats très prometteurs mettent en perspective la réalisation d’un système complet de détection CMOS basé sur ce nouveau conceptThe objective of this work is to develop a novel position sensitive charged particle detector referred to as "3D Silicon Coincidence Avalanche Detector" (3D-SiCAD). The working principle of this novel device relies on a "time-coincidence" mode detection between a pair of vertically aligned Geiger-mode avalanche diodes, with the aim of achieving negligible noise levels with respect to detectors based on conventional avalanche diodes, such as Silicon Photo-Multipliers (SiPM), and, at the same time, providing single charged particle detection capability thanks to the high charge multiplication gain, inherent of the Geiger-mode operation. A 3D-SiCAD could be particularly suitable for nuclear physics applications, in the field of High Energy Physics experiments and emerging Medical Physics applications such as hadron-therapy and Proton Computed Tomography whose future developments demand unprecedented figures in terms of material budget, noise, spatial resolution, radiation hardness, power consumption and cost-effectiveness. In this work, a 3D-SiCAD demonstrator has been successfully developed and fabricated in the Austria Micro-Systems High-Voltage 0.35 μm CMOS technology by adopting a “flip-chip” approach for the 3D-assembling. The characterization results allowed demonstrating the feasibility of this novel device and validating the expected performances in terms of excellent particle detection efficiency and noise rejection capability with respect to background counts
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Gnanaselvam, Pritheesh. "Modeling Turbulent Dispersion and Deposition of Airborne Particles in High Temperature Pipe Flows". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1598016744932462.
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32
PATERNO', ANDREA. "Ultra high-density hybrid pixel sensors for the detection of charge particles". Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2743337.
Testo completo
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Stirnnagel, Kristin. "Herstellung autofluoreszierender retroviraler Partikel zur Analyse der zellulären Aufnahmemechanismen von Foamyviren". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-84198.
Testo completoAbstract (sommario):
Foamyviren (FV) gehören zur Familie der Retroviridae, werden aber aufgrund besonderer Eigenschaften in eine eigene Unterfamilie, die Spumaretrovirinae, eingeordnet. FV besitzen vor allem in vitro einen sehr breiten Tropismus, so dass bisher keine Zelllinie bekannt war, die nicht durch FV infiziert werden konnte. Obwohl diese Besonderheit darauf schließen lässt, dass ein sehr ubiquitäres Molekül auf der Wirtszelloberfläche für die FV-Bindung verwendet wird, ist der Rezeptor für die Virus-Aufnahme noch nicht bekannt. Dass FV einen pH-abhängigen Aufnahmemechanismus verwenden, lässt eine endozytotische Aufnahme vermuten. Dennoch sind die frühen Replikationsschritte, die zur Fusion der viralen und Wirtszellmembran führen, nur unzureichend charakterisiert. Deswegen wurden in der vorliegenden Arbeit funktionelle autofluoreszierende FV hergestellt, um die Bindung und Aufnahmemechanismen foamyviraler Partikel in Wirtszellen mit fluoreszenzmikroskopischen Analysen zu untersuchen.
Mit diesen Methoden konnten erstmalig vier Zelllinien identifiziert werden, die nicht mit FV infizierbar sind, und damit mögliche Kandidaten für die Identifizierung des unbekannten FV Rezeptors darstellen. Des Weiteren wurden die fluoreszierenden FV erfolgreich eingesetzt, um die Fusionsereignisse zwischen viraler und zellulärer Membran in Echtzeit in lebenden Zellen zu untersuchen. Die durchgeführte „Single Virus Tracking“-Analyse zeigte, dass PFV (Prototype FV) Env-tragende Partikel sowohl an der Plasmamembran als auch in vermeintlichen Endosomen fusionieren können, wohingegen SFV (Simian FV) Env-tragende Partikel die Fusion wahrscheinlich nur in Endosomen auslösen können.
Hinweis zur Nutzung der Filmdateien: Öffnen mit QuickTimePlayer bzw. ImageJ
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Benavides, Parra Juan Carlos. "Brownian motion of colloidal particles located near different types of interfaces". Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1011.
Testo completoAbstract (sommario):
Le mouvement Brownien dans l’eau de colloïdes proches d’interfaces de différente nature (eau/air, eau/verre, …) est étudié en utilisant une technique de microscopie numérique permettant de reconstruire les trajectoires individuelles en trois dimensions. Des accords satisfaisants entre les trajectoires et les modèles théoriques publiés ont été trouvés pour les cas les plus simples. En outre, nous proposons une approche théorique capable de passer de la configuration d'interface libre (type eau-air) à l'état lié (type liquide-solide). Nous avons également considéré dans ce cadre la situation dans laquelle une interface solide a été fonctionnalisée et rendue hydrophobe pour comparer le mouvement Brownien près de l’interface avec la même interface solide rendue très hydrophile par un traitement au plasma UV-ozone qui crée des groupes hydroxyle (Si-OH ). Nous avons également étudié l'interaction colloïdale et hydrodynamique avec des interfaces recouvertes d’une membrane biomimétique phospholipidique molle (DOPC en phase fluide) ou gelée (DMPC en phase gel), toutes deux recouvrant le verre (SiO2)We explore the Brownian motion of colloids near different interfaces (water-air, water solid,…) using three dimensional digital video microscopy and reconstruction of singles colloids trajectories in 3D over time. Satisfying agreements between data and published theoretical models were found for simplest cases. In addition we propose a theoretical approach able to transit from the free interface configuration (water-air) to the bound condition (liquid-solid). We also considered within this frame the situation where a solid interface was functionalized with a grafted short alkyl chain (flat and hydrophobic fixed wall) to compare with same solid interface made hydrophilic from a UV-ozone plasma treatment that creates hydroxyl groups (Si-OH). From the stabilization of a phospholipid bilayer, we also studied colloidal and hydrodynamic interaction with a soft (DOPC in Lα) or freezed (DMPC at Lβ) biomimetic membrane covering the solid interface (SiO2 glass)
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Yang, Yidong. "Monitoring cell infiltration into the myocardial infarction site using micrometer-sized iron oxide particles-enhanced magnetic resonance imaging". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/41151.
Testo completoAbstract (sommario):
The cell infiltration into the myocardial infarction (MI) site was studied using magnetic resonance imaging (MRI) with micrometer-sized iron oxide particles (MPIO) as cell labeling probes. MI is a leading cause of global death and disability. However, the roles of inflammatory cells and stem cells during the post-MI remodeling and repair processes are yet to be discovered. This study was to develop noninvasive MRI techniques to monitor and quantify the cellular infiltration into the MI site. MPIO can produce pronounced signal attenuation at regions of interest in MRI. Therefore, cells labeled with these particles can be detected after they are activated and home to the MI site. In the first project, MPIO of various doses were injected into the mouse blood stream 7 days before the MI surgery. Serial MRI was performed at various time points post-MI to monitor the inflammatory cell infiltration into the MI site. Significant signal attenuation caused by labeled cells, in particular macrophages, was observed at the MI site. The study suggests an optimal imaging window should be from 7 to 14 days post-MI, during which the MR signal was inversely proportional to the MPIO dose. The study also suggests an optimal MPIO dose should be between 9.1 and 14.5 µg Fe/g body weight. In the second project, mesenchymal stem cells labeled with MPIO were transplanted into the mouse bone marrow 14 days before the MI surgery. Serial MRI was performed at various time points post-MI to monitor the labeled cells, which mobilized from the bone marrow and homed to the MI site. All the MRI findings were further confirmed by histology. In addition to revealing the characteristics of cell infiltration during MI, this study also provides noninvasive MRI techniques to monitor and potentially quantify labeled cells at the pathological site. The technique can also be used to investigate the function of cells engaged in MI and to test the effect on cell infiltration caused by any treatment strategies.
36
Contin, Giacomo. "The Silicon Strip Detector (SSD) for the ALICE experiment at LHC: construction, characterization and charged particles multiplicity studies". Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3070.
Testo completoAbstract (sommario):
2007/2008La presente tesi descrive le attivita' di ricerca legate alla costruzione, la caratterizzazione e la validazione del rivelatore a micro-strisce di silicio (SSD) per il sistema di tracciamento dell'esperimento ALICE presso il collisionatore LHC al CERN. Nel primo capitolo della tesi si introduce la fisica delle collisioni fra ioni pesanti e si descrivono le principali osservabili che saranno utilizzate dall'esperimento ALICE per studiare la formazione e la successiva evoluzione del Plasma di Quark e Gluoni. Nel secondo capitolo e' presentata una descrizione del rivelatore di ALICE e sono discusse in particolare le caratteristiche del sistema di tracciamento, di cui l'SSD e' parte integrante, e le sue prestazioni in relazione alla fisica di ALICE. La terza parte della tesi riguarda le attivita' correlate alla costruzione e alla caratterizzazione dell'SSD: dopo la produzione e i test di accettazione, e' stata condotta un'indagine estensiva ed approfondita sui moduli difettosi, al fine di comprendere l'origine delle problematiche riscontrate e di elaborare soluzioni appropriate. Il lavoro effettuato ha permesso di recuperare numerosi moduli e di innalzare la qualita' globale del rivelatore. Dopo le operazioni di assemblaggio, il rivelatore nella configurazione finale e' stato completamente caratterizzato prima dell'installazione nel sito sperimentale. Una volta installato, le funzionalita' dell'SSD e la sua integrazione in ALICE sono state infine verificate durante la fase di commissioning, attraverso un elevato numero di acquisizioni di dati di rumore e di raggi cosmici. La caratterizzazione del rivelatore completo ha dimostrato l'importanza di un' efficace correzione hardware del common mode per l'efficienza e la qualita' globali dell'SSD. A tal fine, gli effetti di questa particolare fonte di rumore sono stati studiati attraverso una serie di simulazioni. I risultati di questo studio sono presentati nel quarto capitolo della tesi e due algoritmi sono proposti per un efficiente trattamento e reiezione del rumore di common mode. Infine, nell'ultimo capitolo viene descritto uno studio di fattibilita' della misura della molteplicita' di particelle cariche con l'SSD. In vista della prima fase di acquisizione dati dell'esperimento ALICE, e' stato simulato un campione di eventi protone-protone a 900 GeV di energia; l'efficienza di ricostruzione dei segnali di particella e' stata studiata e misurata in funzione delle caratteristiche funzionali del detector. Infine, la correlazione tra i segnali ricostruiti nell'SSD e le osservabili fisiche simulate dal Monte Carlo e' stata usata per caratterizzare l'interazione primaria.
The present thesis is focused on the construction, characterization and performance assessment of the Silicon Strip Detector (SSD) for the tracking system of the ALICE experiment at LHC. The first part introduces to the physics of heavy ions collisions and describes the main observables which are going to be studied with the ALICE detector as possible signatures of the onset of the Quark Gluon Plasma phase transition. A description of the ALICE detector is presented in the second chapter, with particular emphasis on the tracking system, where the SSD plays an important role, and on its performances related to the ALICE physics topics. The third part of the thesis deals with the activities related to the construction and characterization of the SSD: after the production and the acceptance tests, an extensive work was performed on the malfunctioning modules, in order to find out the origin of several defects and to develop proper solutions. Their application allowed to recover a fair number of modules and to enhance the global quality of the SSD. After the assembling operations, a complete characterization of the detector in the final configuration was performed before its installation in the experimental site. Once installed, it was tested and characterized during the commissioning phase, through a large set of noise and cosmic rays data acquisitions. The characterization showed the relevance of a proper hardware common mode correction for the efficiency and overall quality of the SSD. In order to improve the SSD data quality, the effects of this particular source of noise were studied with a set of simulations. The results are presented in the fourth part of the present thesis; in addition, two different algorithms for an efficient common mode noise treatment and rejection are proposed. In the last part of the thesis, the feasibility of a charged particles multiplicity measurement with the SSD was explored. In view of the first data taking phase of the ALICE experiment, a 900 GeV proton-proton collisions sample was simulated, and the particles signals reconstruction efficiency was studied and measured as a function of the SSD quality, represented by the number of properly operating channels and their noise characteristics. Finally, the correlation between SSD reconstructed signals and the Monte Carlo simulated physical observables was used to characterize the primary interactions.
XXI Ciclo
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Mokhtarpour, Vanaki Shayan. "Numerical investigation of muco-ciliary transport". Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/203744/1/Shayan_Mokhtarpour%20Vanaki_Thesis.pdf.
Testo completoAbstract (sommario):
The human airways are protected from inhaled external substances by an extremely thin layer called airway surface liquid. This film of liquid captures most of the inhaled toxic particles and is constantly propelled back out of the airway by a dense mat of beating hair-like structures, thus cleansing the airways of inhaled pathogens. It is vital to better understand this clearance process under diseased conditions and to predict the fate of therapeutic drug particles after deposition. An advanced numerical model is developed to investigate these objectives, given that the complex nature of lung clearance limits the ability to conduct experiments.
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Firouznia, Mohammadhossein. "The Hydrodynamic Interaction of Two Small Freely-moving Particles in a Couette Flow of a Yield Stress Fluid". Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1502901401749626.
Testo completo
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Kfoury, Adib. "Origine et physicochimie des particules atmosphériques PM₂.₅ dans des villes du littoral de la région Nord-Pas-de-Calais". Thesis, Littoral, 2013. http://www.theses.fr/2013DUNK0403/document.
Testo completoAbstract (sommario):
Les objectifs principaux de cette étude étaient d'acquérir une meilleure connaissance des niveaux d'exposition aux particules fines PM₂.₅ de leur composition chimique et de leurs sources, dans trois villes situées sur la façade littorale de la région du Nord-Pas-de-Calais. Les particules fines ont été collectées dans le cadre de deux campagnes d'échantillonnage menées entre novembre 2010 et avril 2011 (campagne "hiver" à Dunkerque et Boulogne sur Mer ; campagne "printemps" à Dunkerque et Saint Omer). La composition chimique des PM₂.₅ a été déterminée suite à la quantification d'éléments majeurs, d'éléments traces, d'ions hydrololubles et du carbone total. Pour les deux périodes considérées, les concentrations et la composition chimique en PM₂.₅ évoluent en suivant les mêmes tendances sur chacun des sites. L'influence de sources locales a été mise en évidence en comparant l'évolution temporelle et les roses de concentration de certains éléments majeurs et éléments traces, d'un site à l'autre. Cette exploitation a permis de proposer des rapports spécifiques entre éléments, qui peuvent être utilisés comme traceurs de certaines sources anthropiques. Enfin, l'application d'un modèle source-récepteur, basé sur la factorisation matricielle non-négative (NMF), a permis d'identifier les sources principales des PM₂.₅, d'évaluer leur contribution et leur part relative au niveau de chacun des sites étudiésThe main objectives of this study were to acquire a better knowledge on the exposure level to fine PM₂.₅ particles and on their chemical composition and sources, in three cities located on the littoral facade of the Nord-Pas-de-Calais region. The particles were collected following two sampling campaigns held between November 2010 and April 2011 ("winter" campaign in Dunkerque and Boulogne sur Mer ; "Spring" campaign in Dunkerque and Saint-Omer). The chemical composition of the collected PM₂.₅ was determined through the quantification of major elements, trace elements, water soluble ions and total carbon. For the two considered sampling periods, PM₂.₅ concentrations and chemical composition trends followed similar tendencies at each site. Local sources influence was evidenced throughout a comparison of the chronological evolution and concentration roses of some major and trace elements between the sites. This analysis allowed the suggestion of specific elemental ratios, which can be used as tracers of some anthropogenic sources. Finally, the use of a source-receptor model, based on a non-negative matrix factorization (NMF) method, allowed the identification of the main PM₂.₅ sources as well as the evaluation of their relative contributions in each of the studied sites
40
Rane, Nikhil. "Isomap tracking with particle filter". Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1181252052/.
Testo completo
41
Siu, Yam Wing. "Particle tracking in separated flows". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243911.
Testo completo
42
Glasgow, Craig I. "Mixing diagnostics using particle tracking". Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244528.
Testo completo
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Veit, Christin. "Proliferations- und Differenzierungspotential oviner und equiner mesenchymaler Stammzellen nach Markierung mit superparamagnetischen Eisenoxidpartikeln sowie deren Nachverfolgbarkeit mittels Magnetresonanztomographie". Doctoral thesis, Universitätsbibliothek Leipzig, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-78423.
Testo completoAbstract (sommario):
Mesenchymale Stammzellen (MSC) werden bereits in klinischen Studien zur Behandlung verschiedener Krankheiten eingesetzt. Über deren Wirkmechanismus und Verbleib nach Applikation ist jedoch noch wenig bekannt. Die in vivo-Nachverfolgung markierter MSC mittels Magnetresonanztomographie stellt eine mögliche Methode zur Erlangung weiterer Erkenntnisse dar. Zu diesem Zweck können die MSC mittels superparamagnetischen Eisenoxid (SPIO)-Partikeln markiert werden. In dieser Arbeit wurden 3 verschiedene SPIO-Produkte zur Markierung oviner und equiner MSC verwendet: Endorem™, Resovist® und Molday ION Rhodamine B™. Die Produkte wurden hinsichtlich ihrer Einflüsse auf die biologischen Eigenschaften der MSC, ihrer Markierungseffizienz und –selektivität verglichen. Desweiteren wurde die produktspezifische magnetresonanztomographische Nachverfolgbarkeit der SPIO-markierten MSC untersucht. Weiterführendes Ziel war die Selektion des am besten geeigneten SPIO-Produktes für die Verwendung in einem in vivo-Großtierversuch zur magnetresonanztomographischen Nachverfolgung SPIO-markierter MSC nach Applikation in arthrotische Gelenke. Die MSC wurden dazu aus dem Knochenmark von je 5 gesunden Schafen und Pferden isoliert, bis zur Passage 4 (P4) expandiert und schließlich mit den verschiedenen SPIO-Produkten markiert. Unmarkierte MSC der gleichen Tiere dienten zur Kontrolle. Proliferationsvermögen sowie tripotentes Differenzierungspotential wurden in vitro untersucht. Zur Evaluierung von Markierungsselektivität und -effizienz der SPIO-Produkte wurden die MSC ab der P4 bis zur P7 wöchentlich passagiert. Ein semiquantitatives histologisches Auswertungssystem basierend auf der Preußisch Blau-Färbung sowie T2*w-GRE-Sequenzen an einem 0,5T-MRT-System wurden zur Evaluierung genutzt. Markierungsselektivität bezeichnete die intra- oder extrazelluläre Lokalisation der SPIO-Partikel. Markierungseffizienz beschrieb die Menge intrazellulär vorhandener SPIO-Partikel. Es wurde gezeigt, dass sich ovine und equine MSC mit allen 3 untersuchten SPIO-Produkten erfolgreich markieren ließen. Die Ergebnisse der in vitro-Untersuchungen ergaben keine Unterschiede zwischen SPIO-markierten und unmarkierten MSC hinsichtlich des Proliferationsvermögens, der adipogenen oder osteogenen Differenzierungsfähigkeit. Jedoch wurde eine deutliche Verminderung des chondrogenen Differenzierungspotentials SPIO-markierter MSC beobachtet, welche von der Menge intrazellulär vorhandener SPIO-Partikel und somit von der Markierungseffizienz abhängig war. Zum Zeitpunkt der initialen Markierung konnte nur Molday ION Rhodamine B™ eine selektive und effiziente Zellmarkierung gewährleisten. Mit Endorem™ konnte eine selektive, jedoch keine ausreichend effiziente Zellmarkierung erreicht werden. Resovist® dagegen bewirkte zwar eine effiziente, aber sehr unselektive initiale Zellmarkierung: Mittels Preußisch Blau-Färbung wurde gezeigt, dass große Mengen von SPIO-Partikeln nur extrazellulär anhefteten. Die 3 verschiedenen SPIO-Produkte führten weiterhin zu unterschiedlich starken hypointensen MRT-Signalen der markierten MSC, welche im Verlauf der 3-wöchigen Versuchsdauer bei allen 3 Produkten stetig abnahmen. Unmarkierte MSC waren isointens, also mittels MRT nicht darstellbar und daher nicht nachverfolgbar. Stets verursachten Resovist®-markierte MSC das stärkste hypointense MRT-Signal, gefolgt von Molday ION Rhodamine B™ und Endorem™. Resovist®-markierte MSC konnten mittels MRT bei beiden Spezies über den längsten Zeitraum nachverfolgt werden (ovine MSC bis 16 Tage, equine MSC bis 23 Tage nach Markierung). Aufgrund der exzellenten initialen Markierungseigenschaften (hohe Markierungsselektivität und –effizienz sowie gute Nachverfolgbarkeit) eignet sich Molday ION Rhodamine B™ besonders gut für die SPIO-Markierung von MSC zur Nachverfolgung mittels MRT. Molday ION Rhodamine B™ verspricht somit eine erfolgreiche Anwendung in einem in vivo-Versuch zur magnetresonsztomographischen Nachverfolgung von MSC nach Applikation in arthrotische GelenkeMesenchymal stem cells (MSC) are already used in clinical studies for treatment of different diseases. However, their mechanism of action and fate after application are still not fully understood. In vivo tracking of labeled MSC via magnetic resonance imaging (MRI) is a possible method to achive further knowledge. For this purpose MSC can be labelled with superparamagnetic iron oxide (SPIO) particles. For this study 3 different SPIO products were employed for labelling of ovine and equine MSC: Endorem™, Resovist®,, and Molday ION Rhodamine B™. The products were compared in terms of their influence on biologic behaviour of the MSC, their labelling efficiency, and selectivity. Furthermore, product specific magnetic resonance traceability of SPIO labelled MSC was evaluated. Final aim was the selection of the most suitable SPIO product to be used in an in vivo large animal study employing MRI tracking of SPIO labelled MSC after application into osteoarthritic joints. MSC therefore, were isolated from bone marrow of each 5 healthy sheep and horses, expanded up to passage 4 (p4), and labelled by the different SPIO products. Unlabelled MSC from the same animals served as control. Proliferation potential and tripotent differentiation capacities were assessed in vitro. For evaluation of labelling selectivity and efficiency of the SPIO products MSC were passaged weekly from p4 up to p7. Semiquantitative histological scoring based on Prussian blue staining and images using T2*w GRE sequences in a 0.5T MRI system were used. Labelling selectivity describes the intra- or extracellular localisation of the SPIO particles. Labelling efficiency describes the amount of intracellular SPIO particles. It was shown that ovine and equine MSC could be successfully labelled by all 3 evaluated SPIO products. The results of the in vitro experiments did not show differences between labelled and unlabelled MSC in terms of proliferation potential, adipogenic or osteogenic differentiation capacities. However, an inhibited chondrogenic differentiation capacity of SPIO labelled MSC was observed, which was dependend on the amount of intracellular SPIO particles and therefore, also on labelling efficiency. At the time of initial labelling, only Molday ION Rhodamine B™ showed selective and efficient cell labelling. With Endorem™ selective, but not efficient cell labelling was achieved. Resovist®, in contrast, caused efficient but very unselective initial cell labelling: By Prussian blue staining it was shown that large amounts of SPIO particles were attached extracellularly. These 3 different SPIO products led to variable hypointense MRI signals of the labelled MSC which decreased in all 3 products during the 3 week study period. Unlabelled MSC were isointense, thus not visible, and therefore, not traceable using MRI. At every point of time, Resovist® labelled MSC resulted in the most hypointense MR signals, followed by Molday ION Rhodamine B™ and Endorem™. Resovist® labelled MSC were traced over the longest time span (ovine MSC until 16 days, equine MSC until 23 days post labelling). Due to excellent initial labelling properties (high labelling efficiency and selectivity, good traceability) Molday ION Rhodamine B™ suits best for SPIO labelling of MSC to be tracked by MRI. Molday ION Rhodamine B™ therefore, promises a successful use in an in vivo study using MRI for MSC tracking after application into osteoarthritic joints
44
Desai, Kalpit V. Bishop Gary. "Agnostic tracking nanoscale, high bandwidth, 3D particle tracking for biology /". Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1883.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the joint Department of Biomedical Engineering." Discipline: Biomedical Engineering; Department/School: Medicine.
45
Zouaghi, Ayyoub. "Manipulation de particules diélectriques micrométriques par ondes électrostatiques progressives et stationnaires - Études théorique, expérimentale et numérique". Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2296.
Testo completoAbstract (sommario):
Les convoyeurs électrostatiques à ondes progressives (COP) et stationnaires (COS) se présentent comme des moyens avantageux pour manipuler et transporter efficacement des particules sur une surface. L’objectif de cette thèse est d’étudier le comportement de particules diélectriques micrométriques sur ces systèmes. Les études expérimentales commencent par la caractérisation granulométrique et optique des particules et l’analyse de leur charge. Ensuite, l’efficacité de déplacement des particules par les deux types de convoyeurs est étudiée dans différentes conditions. Par ailleurs, les trajectoires des particules sont visualisées en utilisant une caméra ultra rapide. Un post-traitement des images obtenues en utilisant la vélocimétrie par suivi de particules (PTV) est mené pour calculer et étudier la vitesse des particules en fonction de différents paramètres. Les études théoriques et numériques menées avaient pour objectif d’étudier les ondes du potentiel électrique, la variation spatio-temporelle du champ électrique, et le bilan des forces mises en jeu. La dernière partie concerne la modélisation des trajectoires et le calcul numérique de la vitesse moyenne, ainsi que de la distance de déplacement des particules. Les résultats obtenus par modélisation sont en accord avec les observations et les calculs expérimentaux. Plusieurs modes de mouvement sont obtenus en fonction de la fréquence, la tension, la charge et la taille des particules. Les particules sont transportées plus efficacement dans le COP lorsqu’elles sont en mode synchrone sautillant. L’augmentation du nombre de phases permet à la fois de minimiser l’effet des ondes harmoniques inverses et d’augmenter la vitesse de propagation de l’onde directe ; cela mène à un déplacement plus rapide et plus loin des particules dans une seule direction, ce qui augmente l’efficacité du systèmeTraveling and standing wave electrostatic conveyors (TWC and SWC) are presented as advantageous techniques to effectively manipulate and transport particles on a surface. The aim of this work is to study the behavior of micrometer particles on these systems. Experimental studies begin with granulometric and optical characterization of particles and the measurement of their charge. Then, the particles displacement efficiency in both types of conveyors is studied under different conditions. In addition, the trajectories of the particles are visualized using high speed camera. The post-processing of the obtained images using Particle Tracking Velocimetry technique (PTV) is carried out to calculate and study the particles mean velocity and how it is affected by different parameters. The theoretical and numerical studies carried out aim to study the electric potential waves, the spatial and temporal variation of the electric field and the balance of the forces acting on particles. The last part concerns the modeling of particles trajectories and the numerical computation of their average velocity and displacement distance. The results obtained by modeling are in good agreement with the experimental observations and calculations. Several modes of movement are obtained depending on frequency, applied voltage value, as well as particle charge and size. Particles are transported more efficiently in the TWC when they are in synchronous hopping mode. Increasing the number of phases can minimize the effect of the backward harmonic waves and increase the speed of propagation of the forward wave that may help the particles to move faster and farther in one direction and lead to better displacement efficiency
46
Bombrun, Maxime. "Characterisation of volcanic emissions through thermal vision". Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22600/document.
Testo completoAbstract (sommario):
En avril 2010, l’éruption de l’Eyjafjallajökull (Islande) a projeté des cendres sur toute l’Europe pendant six jours, causant d’importantes perturbations aériennes. Cette crise a soulevé la nécessité de mieux comprendre la dynamique des panaches lors de l’émission, de la dispersion, et de la retombée afin d’améliorer les modèles de suivis et de prédiction de ces phénomènes. Cette éruption a été classée comme Strombolienne. Ce type d’éruption offre un large panel de manifestations (coulée de lave, paroxysmes) et peut être utilisé comme indicateur d’éruptions plus dangereuses. Les éruptions stromboliennes permettent généralement une observation à quelques centaines de mètres tout en assurant la sécurité des opérateurs et du matériel. Depuis 2001, les caméras thermiques ont été de plus en plus utilisées pour comprendre la dynamique des évènements volcaniques. Toutefois, l’analyse, la modélisation et le post-traitement de ces données thermiques n’est toujours pas totalement informatisé. Durant ma thèse, j’ai étudié les différentes composantes d’une éruption strombolienne depuis les fines particules éjectées au niveau du cratère jusqu’à la vision d’ensemble offerte par les images satellites. Dans l’ensemble, j’ai caractérisé les émissions volcaniques à travers l’imagerie thermiqueIn April 2010, the eruption of Eyjafjallajökull (Iceland) threw volcanic ash across northwest Europe for six days which led to air travel disruption. This recent crisis spotlighted the necessity to parameterise plume dynamics through emission, dispersion and fall out as to better model, track and forecast cloud motions. This eruption was labeled as a Strombolian-to-Sub-Plinian eruption type. Strombolian eruptions are coupled with a large range of volcanic event types (Lava flows, paroxysms) and eruption styles (Hawaiian, Sub-plinian) and offer a partial precursory-indicator of more dangerous eruptions. In addition, strombolian eruptions are small enough to allow observations from within few hundred meters with relative safety, for both operators and material. Since 2001, thermal cameras have been increasingly used to track, parameterise and understand dynamic volcanic events. However, analyses, modelling and post-processing of thermal data are still not fully automated. In this thesis, I focus on the different components of strombolian eruptions at the full range of remote sensing spatial scales. These range from millimeters for particles to kilometers for the entire features via satellite images. Overall, I aim to characterise volcanic emissions through thermal vision
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Doyle, Thomas Edward. "Optical tracking of charged particle distributions". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq30839.pdf.
Testo completo
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Kambhampati, Srisumakanth. "Target/Object tracking using particle filtering". Diss., Wichita State University, 2008. http://hdl.handle.net/10057/2003.
Testo completoAbstract (sommario):
Particle filtering techniques have captured the attention of many researchers in
various communities, including those in signal processing, communication and image processing. Particle filtering is particularly useful in dealing with nonlinear state space models and non-Gaussian probability density functions. The underlying principle of the methodology is the approximation of relevant distributions with random measures composed of particles (samples from the space of the unknowns) and their associated weights. This dissertation makes three main contributions in the field of particle filtering. The first problem deals with target tracking in radar signal processing. The second problem deals with object tracking in video. The third problem deals with estimating error bounds for particle filtering based symbol estimation in communication systems.Thesis (Ph.D.)--Wichita State University, College of Engineering Dept. of Electrical and Computer Engineering
Includes bibliographic references (leaves 69-76)
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Hatem, Ayman Bargas. "Software development for particle tracking velocimetry". Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362901.
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Katayama, Yoshihiko. "3D particle tracking in cellular systems". München Hieronymus, 2009. http://d-nb.info/994986777/04.
Testo completo