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1
Brehm, Oliver. "Untersuchungen zur Einführung der polyfluorierten Gruppen CF3(CF2)5-C2H4 und C6F5 in Alkyl- und Arylchlorsilane." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970509405.
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Hargreaves, Leigh Randall, and harg0032@flinders edu au. "Absolute Electron Scattering Cross Sections for the CF2 Radical." Flinders University. School of Chemsitry, Physics and Earth Sciences, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20080430.103821.
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This thesis describes an experimental study of elastic electron scattering from
CF2 radicals, in the intermediate energy regime. Measurements of the absolute
differential, integral and momentum transfer cross sections for CF2 are presented.
These measurements were performed using a new crossed beam spectrometer,
incorporating a supersonic gas source and normalised using a new technique,
with both of these features being extensively developed as a major part of this
study.
The organisation of this thesis is as follows: A brief justification for this research
is presented in Chapter 1, together with a review of the spectroscopy and
electron collision cross sections which are currently available for the CF2 radical.
The crossed beamed apparatus and experimental techniques used to perform the
present cross section measurements are then described in detail in Chapter 2, and
the theory behind the new normalisation technique is subsequently presented in
Chapter 3.
Results from the present study are given in Chapter 4. Firstly, differential cross
sections measurements for stable molecules are presented, to validate the new
normalisation method. Characterisation data for the dissociation dynamics of
C2F4 into CF2 radicals are then presented and, finally, differential cross section
measurements for the CF2 radical are explored. Where possible, the measured
data for CF2 are compared against results from theoretical calculations and the
implications of the present results are discussed. The major findings of this
research are then summarised in Chapter 5, and directions for future research
using the present apparatus are also discussed here. Finally, some additional
findings from this research and calibration data for the current apparatus are
given in the appendices.
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Zhou, Chun. "CHEMICAL DURABILITY STUDIES OF IONOMERS AND MODEL COMPOUNDS FOR FUEL CELL APPLICATIONS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1199478916.
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Pouzet, Eric. "Etude du comportement moléculaire de l'alcane semifluoré F(CF2)8(CH2)18H en couches minces déposées sur substrats liquide et solide : détermination structurale et organisation interfaciale." Paris 6, 2003. http://www.theses.fr/2003PA066571.
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Medaghri-Alaoui, Abdelouahid. "Réduction électrochimique du dibromodifluorométhane. Formation du radical anion (CF2Br2). ̱, du radical CF2Br. , du bromodifluorométhylure CF2Bṟ et du difluorocarbène : cf2." Montpellier 2, 1994. http://www.theses.fr/1994MON20135.
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La presente etude porte sur le comportement du dibromodifluoromethane lors d'une reduction a une electrode de carbone. On montre que cette reduction est bielectronique conduisant au difluorocarbene, via le bromodifluoromethylure. Les electrolyses conduites en presence de diverses olefines, mettent en evidence la formation de composes resultant de la presence intermediaire du radical bromodifluoromethyle: composes d'addition dans le cas de l'hex-i-ene, oligomeres dans le cas de l'acrylate d'ethyle, composes d'addition et difluorocyclopropane dans le cas du 2,3-dimethylbut-2-ene. Une etude des mecanismes mis en jeu, en voltametrie a variation lineaire de potentiel, permet de preciser les points suivants: la reduction cathodique du dibromodifluoromethane, correspond initialement a la formation du radical anion dibromodifluoromethane. Celui-ci diffuse au voisinage de l'electrode et se decompose en radical bromodifluoromethyle et ion bromure. La vitesse de coupure correspondante a pu etre calculee. Le radical libere peut reagir avec une olefine, ou en l'absence etre reduit en bromodifluoromethylure, connu comme source de difluorocarbene. On a pu montrer que les difluorocyclopropanes formes resultent en partie de la cyclisation des adducts intermediaires et non uniquement d'une reaction directe du difluorocarbene. Les vitesses de reactions du radical bromodifluoromethyle sur les trois olefines etudiees ont ete determinees. Au total, la reduction cathodique du dibromodifluoromethane montre que l'electrochimie permet de developper a la fois les potentialites des methodes radicalaires d'activation de ce compose et les methodes de reduction sur les metaux conduisant au carbene libre. En particulier, la formation initiale d'un radical anion par transfert monoelectronique a pu etre etablie
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Bulcourt, Nicolas. "Etude des radicaux CF et CF2 dans une décharge capacitive double fréquence 27 et 2 MHz en Ar/O2/C4F8." Paris 11, 2007. http://www.theses.fr/2007PA112009.
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La microélectronique consiste en l’élaboration de structures nanométriques. L’utilisation des plasmas est donc nécessaire. Ceux utilisés pour la gravure de diélectriques et de matériaux « low-k » sont des plasmas capacitifs utilisant un gaz carbonofluoré excité par une double fréquence produisant des radicaux de type CFx qui gravent SiO2 mais également polymérisent sur les surfaces. Les plus petits radicaux présents sont CF et CF2. Le travail présenté dans cette thèse porte donc sur l’étude de ces radicaux dans une décharge capacitive double fréquence 27+2 MHz en Ar/O2/C4F8. L’objectif est de déterminer et comprendre la répartition des densités, des températures rotationnelles et vibrationnelles dans le plasma. Le réacteur est de type Exelan® modifié. Il est constitué de deux électrodes plates et circulaires d’un rayon de 10 cm et séparées de 25 mm. Des anneaux en quartz permettent le confinement du plasma. Un substrat de silicium de 20 cm de diamètre est placé sur l’électrode de puissance. Nous avons choisi d’utiliser la spectroscopie d’absorption UV large bande qui n'est pas intrusive et est facile d'utilisation. Les spectres expérimentaux ont été mesurés pour déterminer les profils axiaux et radiaux. Pour cela, ils ont été comparés à ceux obtenus par simulation. Pour le radical CF, nous avons utilisé le logiciel LIFBASE pour simuler les spectres d’absorption. Pour CF2, nous avons, avec l’aide de nombreux chercheurs, développé notre propre programme. Les profils radiaux ont été obtenus une utilisant la méthode d’inversion d’Abel et une méthode d’inversion récursive. Les zones de création, de destruction et de chauffage ont été identifiées. Les résultats montrent que le plasma n’est pas uniforme en phase gazeuse mais qu’il tend à le devenir au dessus du substrat lorsque la puissance augmente. Le chauffage des modes de vibration proviendrait de mécanismes collisionnels électroniques. Ce travail est une première étape pour une meilleure compréhension de ce type de déchargeMicroelectronics is used to make nanometre structures. This can only be achieved by using plasmas. They are used in a lot of processes as deposition and etching of low-k and dielectric materials. For these last applications, capacitive plasmas with fluorocarbon gases excited by a dual frequency are used. They product CFx radicals which can etch SiO2 and polymerise on the surfaces. The smallest radicals in these plasmas are CF and CF2. This work is on plasma physics and on the study of the CF and CF2 radicals in a dual-frequency 27+2 MHz capacitive discharge in Ar/O2/C4F8. The aim was to determine and to understand the density, the rotational and the vibrational distributions in the discharge. The experimental reactor we used is a modified Exelan® reactor of LAM Research Corp to permit the diagnostic of the plasma with conditions close to industrial conditions. It has two plate electrodes with a 10 cm radius. The gap is 25 mm. Quartz rings permit to confine the plasma. A 200 mm silicon wafer is on the powered electrode. We chose to use the UV broad-band absorption spectroscopy. This technique is not intrusive and it is simple to use. The experimental spectra were measured to determine the axial and radial distributions. For this, they were compared to those obtained by simulation. For the CF radical, we used the software LIFBASE to simulate the absorption spectra. But for CF2, thanks to others researchers, we have developed our own program. The radial profiles were obtained using the Abel inversion method and a recursive method. We have been able to identify the different production and destruction areas and the warming areas in the discharge. The results show that the plasma is not uniform in the gas phase but it tends to be uniform above the wafer when the power increases. The vibration modes are essentially warmed by electronic impacts. This study is a first step to understand this kind of discharge and others studies will help us to have a better knowledge of the different mechanisms
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Mehmetli, Bulent Ahmet. "Engineering studies of a pilot plant for laser isotope separation of 13[superscript]C by multiphoton dissociation of CF2[subscript]HCl /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848078452332.
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Hessami, Sanna. "Hur utformar lärarna undervisningen för att stimulera språket hos elever med ett annat modersmål än svenska? : Om tvåspråkighet." Thesis, Mälardalen University, School of Education, Culture and Communication, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-7794.
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Syftet med undersökningen var att ta reda på hur lärare utformar sin undervisning för att stimulera språket hos elever med ett annat modersmål än svenska. Jag koncentrerade mig på två skolor som ligger nära varandra för att se vilka likheter och skillnader det finns mellan skolorna gällande undervisningen. Jag ville även veta om det finns något samarbete mellan klasslärare och modersmålslärare och hur det i så fall ser ut. Jag gjorde intervjuer med rektorer och lärare för att få svar på mina frågor. Jag intervjuade en modersmålslärare för att få en inblick i hur han arbetar. Jag har även gjort två observationer, en under en lektion i svenska i den vanliga undervisningen och en under en modersmålsundervisning.
Resultaten visar att lärarna försöker se till tvåspråkiga elevernas förutsättningar och behov och de flesta lärarna var eniga om att det mest utvecklande för dessa elever är att arbeta med språket på olika sätt. Det finns samarbete mellan klasslärarna och modersmålslärarna, men bara till viss del. En av skolorna har fler elever med ett annat modersmål än svenska och därför även mer erfarenhet i att undervisa dem.
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Sölter, Lars. "Experimentelle und theoretische Untersuchungen der Dissoziationen von Tetrafluorethen, Hexafluorpropen und Hexafluorcyclopropan." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5F20-0.
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Berezkin, Kirill. "High-resolution infrared spectroscopy of the CH2 = CD2 molecule." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCK044/document.
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Dans cette thèse, nous avons considéré les spectres de la molécule CH2=CD2. Dans la partie expérimentale, nous avons enregistré des spectres infrarouges à haute résolution (~ 0,0025 cm-1) et fait une attribution complète des transitions enregistrées. Nous avons pu assigner pour la première fois un grand nombre de transitions des combinaisons peu intenses υ4+υ10, υ4+υ7 et de l'harmonique 2υ10; de bandes interdites par symétrie υ4, υ7+υ10, υ8+υ10; et des bandes «chaudes» υ7+υ10–υ10 et υ8+υ10–υ10. Pour la première fois, plus de 7000 transitions inconnues des bandes fondamentales υ2, υ3, υ6, υ7, υ8, υ10, υ12 et de l'harmonique 2υ7 ont été assignées. Sur la base de la théorie des opérateurs de perturbation et des propriétés de symétrie de la molécule étudiée, nous avons construit un hamiltonien effectif puis ajusté les énergies vibrationnelles expérimentales de quatorze états vibrationnels. De cette étude, il a résulté un écart-type pour l'ajustement d'environ (1,7–2,5)×10−4 cm−1 pour diverses régions spectrales. Nous avons également mesuré les valeurs expérimentales des intensités et des demi-largeurs et avons calculé les paramètres du moment dipolaire effectif et des coefficients d'auto-élargissement de la molécule CH2=CD2In this thesis we have considered spectra of the CH2=CD2 molecule. In the experimental part we recorded high-resolution (~ 0.0025 cm-1) infrared spectra and made full assignment of the recorded transitions. We were able to assign for the first time a lot of transitions to the weak combinations υ4+υ10, υ4+υ7 and 2υ10 overtone; forbidden due to the symmetry υ4, υ7+υ10, υ8+υ10; «hot» υ7+υ10–υ10 and υ8+υ10–υ10 bands. More than 7000 previously unknown transitions were assigned to the fundamental bands υ2, υ3, υ6, υ7, υ8, υ10, υ12 and 2υ7 overtone. On the base of operator perturbation theory and the symmetry properties of the studied molecule, we constructed an effective Hamiltonian and then fitted experimental ro-vibrational energies of fourteen vibrational states. As a result, rms-deviation of the fit was about (1.7–2.5)×10−4 cm−1 for various spectral regions. We measured also experimental values of intensities and halfwidths and calculated parameters of effective dipole moment and self-broadening coefficients of the СH2=СD2 molecule
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Sasaki, K., H. Furukawa, K. Kadota, and C. Suzuki. "Surface production of CF, CF_2 , and C_2 radicals in high-density CF_4/H_2 plasmas." American Institute of Physics, 2000. http://hdl.handle.net/2237/7036.
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Aguirre, John. "Study of 3-Dimensional Co-Flow Jet Airplane and High-Rise Building Flow Using CFD Simulation." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_theses/181.
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The purpose of this thesis is to design and study an aircraft which implements the Co-Flow Jet (CFJ) airfoil concept, as well as to study the CAARC standard highrise building. The design concept is verified mainly by the use of a Computational Fluid Dynamics (CFD) package. A thorough methodology for geometry and mesh generation is developed, and subsequently applied to the two cases. The first case studied is that of the CFJ Airplane (CFJA). It consists of a threedimensional, highly blended, ying wing geometry implementing the Co-Flow Jet airfoil concept. Though a thorough comparison to a baseline geometry, it is shown that usage of the CFJ airfoil cross-section greatly improves aircraft performance by increasing lift, reducing drag, and providing a source of thrust over the operational range of angles of attack. A steady state CFD simulation is used for this case, as the air ow around an airfoil cross-section is inherently steady for attached ows. CFD results are used to support the Engineless Aircraft" concept, where the CFJ airfoil is used as the sole form of propulsion. The second case studied consists of a rectangular high-rise building undergoing a wind condition with Mach number of 0:1 and a Reynolds number of 160000. Due to the non-streamlined geometry of the building cross-section, aerodynamic instabilities due to uid separation are present, and therefore an unsteady CFD analysis is necessary to fully resolve all of the ow phenomena. Preliminary steady state results are presented, and a plan is laid down for the future study of this highly complex case. Results are presented for a variety of angles of attack in the case of the CFJA, and for the main ow direction in the case of the CAARC building. Results are compared with baseline geometry in the case of the CFJ Airplane. The CFJ Airplane case is simulated using a 3rd order steady state scheme, which is sufficient to achieve valid results for the ow regime. The CAARC building, which has inherent ow separation, requires the use of high order schemes.
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Sénéchal, Ulf. "Holzverbrennung in Kaminöfen mit Keramikfilter - experimentelle Untersuchungen und mathematische Modellierung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138497.
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Zur Verringerung von Schadstoffemissionen werden in Kaminöfen oft Keramikfilter integriert, die Staub und Ruß aus dem Abgas entfernen sollen. Die Filter beeinflussen jedoch die strömungsmechanischen, energetischen und chemischen Vorgänge im Feuerraum. Für die Auslegung und die praktische Anwendung der Filter ist die Kenntnis der Einflussgrößen und deren Umfang nötig.
Mit Hilfe von experimentellen und numerischen Untersuchungen wurden die Stoff- und Energietransportvorgänge von zwei Kaminöfen charakterisiert. Zur Bestimmung der Massenabnahme von Holzscheiten kam eine neue, praktisch leicht umsetzbare Methode, basierend auf einer Schockkühlung mit flüssigem Stickstoff, zum Einsatz. Parallel dazu wurde die Massenabnahme der Holzscheite mit Hilfe einer Online-Massenbestimmung mittels Waage aufgezeichnet und ein Verfahren zur Bestimmung der Abbrandkinetik entwickelt. Die Schwierigkeiten der messtechnischen Erfassung und Auswertung der instationären Vorgänge wurden dargestellt und diskutiert.
Für die zwei Kaminöfen sind numerische Simulationen mit der Software ANSYS CFX erstellt worden, die weitgehend auf realen Geometrien beruhen. Vergleichende null- und eindimensionale Simulationen mit unterschiedlichen Reaktionsmechanismen und gasförmigen Brennstoffen wurden realisiert und hinsichtlich ihrer Eignung für die Berechnung von Kaminöfen untersucht.
Nach erfolgter Validierung wurde ein parametrisches Simulationsmodell eines Kaminofens erstellt. Mit diesem wurde eine Parameterstudie zur Untersuchung der Veränderung der Zielgrößen Heizleistung, Kohlenmonoxid- und Rußkonzentration sowie Gesamt- und Sekundärluftmassenstrom in Abhängigkeit der Parameter durchgeführt.
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Molaei, Chalchooghi Mazaher. "Modelling and CFD simulation of a fluidized bed process for the capture of C02 from fossil fuel combustion sources." Thesis, University of Greenwich, 2013. http://gala.gre.ac.uk/11960/.
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Fossil fuels provide the main source of energy for power generation in existing power plants. A mitigation option to reduce carbon dioxide (CO2) emission from existing power plants with fossil fuel combustion is the sequestration of carbon dioxide and storage in geological formations, in the ocean or for use in industrial processes. CO2 capture from combustion exhaust gases by mineral carbonation using a fluidised bed is studied in this project. CFD modelling has been used to study the efficiency of CO2 capture in a fluidized bed reactor containing a solid sorbent Calcium Oxide (CaO). This present work seeks to maximize CO2 conversion by a systematic modification of the flow domain. In particular, it is intended to use a convergent-divergent geometry to control the velocity of particles in the reaction domain thereby keeping the particles in the domain as long as possible. This is expected to improve the performance of the system as more time is allowed for any remaining CO2 to react with CaO and then be removed in the calcination stage. Further the effect of other key parameters such as particle size, CO2 concentration of flue gas and mass loading of solid sorbent have also been investigated. A Lagrangian/Eulerian scheme has been developed for this purpose, which uses a particle tracking model to describe CaO particle trajectories and mass, momentum and energy exchange with the carrier gas, entering the reactor in a typical flue gas composition. A steady-state condition is assumed, with each trajectory representing a parcel of particles of a given mass and diameter. The number of particles entering the fluidised bed is kept constant, and the fluidization velocity is chosen so that particles remain in the reactor. As the carbonation progresses, heavier well-reacted particles are collected at the bottom of the reactor. In the case of a non-uniform size distribution, fine particles would escape from the top of the reactor; in order to keep such particles within the domain the geometry was modified to increase the residence time of particles and to obtain maximum conversion. CO2 reduction of the order of 90% was achieved in a single pass, with a mass loading of 2.5 times of equivalent solid sorbent to CO2 in gas.
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Grisin, Aleksandr. "Diastereoselective synthesis of syn-1,3-polyols and studies towards the C1-C31 and C32-C52 fragments of amphidinol 3." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/10373/.
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Diastereoselective Synthesis of syn-1,3-Polyols The stereoselective construction of polyacetate 1,3-diols has attracted considerable attention due to the ubiquity of this motif in complex biologically active polyene macrolides (amphotericin B, RK-397, mycoticin, candidin). We have developed a highly stereoselective bismuth(III)-mediated two-component hemiacetal/oxa-conjugate addition reaction, which directly provides syn-1,3-diols in the form of cyclic acetals having an adjacent electron-withdrawing group in the form of aldehydes and ketones. The scope and limitations of this transformation were examined and culminated with the synthesis of the C18-C28 fragment of antibiotic RK-397. Studies towards the C1-C31 and C32-C52 Fragments of Amphidinol 3 Temporary-tethered reactions provide an important strategy for target- directed synthesis, since they circumvent the problems encountered with entropically unfavorable reactions. The temporary silicon-tethered ring-closing metathesis (TST- RCM) allows for the highly (Z)-selective coupling of mixed silaketals in the formation of the medium sized rings. The latter compounds can undergo a substrate controlled stereoselective electrophilic functionalisation, for example, hydroboration, dihydroxylation or epoxidation, and produce polyoxygenated motifs that are present in many biologically important natural products. In the course of these studies we have developed a highly convergent asymmetric synthesis of the C1-C31 polyol fragment of amphidinol 3, where the TST-RCM/hydroboration reaction is successfully employed for the efficient coupling ii of the C16-C23 and C24-C30 units of the natural product with concomitant introduction of the crucial propionate-type C23-C24 stereocentres. In the final part of thesis the investigation of the stereoselective dihydroxylation reaction of mixed syn and anti eight-membered cyclic silaketals was carried out. The resulting oxygenated products can be efficiently transformed via an intramolecular cyclisation of δ-hydroxy epoxides into the highly substituted syn- and anti-tetrahydropyrans (THPs), a strategy that could also have application in related natural products, for example, ladder polyether polyketides. The merit of the developed methodology was highlighted in the asymmetric synthesis of the common C31(52)-C39(44) THP fragment of amphidinol 3, which could be ultimately used in the bidirectional route towards the bis-THP segment of the natural product.
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Stareček, Jakub. "Návrh axiálního čerpadla pro zadané parametry." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232102.
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This master's thesis contains basic hydraulic calculations, design and optimalization of both the rotor and stator part of the axial pump. There is also included an analysis of the principle and function of hydrodynamic axial pumps. The last part of this work is focusing on the strength calculations and flow simulations using CFD.
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Matusis, Alec (Alec L. ). 1971. "CFT correlation functions from AdS/CFT correspondence." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85332.
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Thiart, Anja. "A CFD study of fuel evaporation and related thermofluid dynamics in the inlet manifold, port and cylinder of the CFR octane engine." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/11992.
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Includes abstract.Includes bibliographical references.
Spark Ignition (SI) engine fuels' anti-knock properties are measured in the Co-operative Fuel Research (CFR) engine under two different test conditions as prescribed by the American Society for Testing and Materials (ASTM) for Research Octane Number (RON) and Motor Octane Number (MON) ratings. Recent research has been focused on determining whether the numerical difference between RON and MON, known as Octane Sensitivity (OS), is a result of the chemical or physical properties of the fuel. The present research examined the effect that the operating environment has on fuel evaportion, and thus OS, in the CRF engine.
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Motamedi, Masoud. "The millimetre-wave rotational spectra of CFâ†3CCH, CFâ†3CCD and CFâ†3CN." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308975.
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Hari, Sridhar. "Computational Fluid Dynamics (CFD) simulations of dilute fluid-particle flows in aerosol concentrators." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/1619.
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In this study, commercially available Computational Fluid Dynamics (CFD) software, CFX-4.4 has been used for the simulations of aerosol transport through various aerosol-sampling devices. Aerosol transport was modeled as a classical dilute and dispersed two-phase flow problem. Eulerian-Lagrangian framework was adopted wherein the fluid was treated as the continuous phase and aerosol as the dispersed phase, with a one-way coupling between the phases. Initially, performance of the particle transport algorithm implemented in the code was validated against available experimental and numerical data in the literature. Code predictions were found to be in good agreement against experimental data and previous numerical predictions. As a next step, the code was used as a tool to optimize the performance of a virtual impactor prototype. Suggestions on critical geometrical details available in the literature, for a virtual impactor, were numerically investigated on the prototype and the optimum set of parameters was determined. Performance curves were generated for the optimized design at various operating conditions. A computational model of the Linear Slot Virtual Impactor (LSVI) fabricated based on the optimization study, was constructed using the worst-case values of the measured geometrical parameters, with offsets in the horizontal and vertical planes. Simulations were performed on this model for the LSVI operating conditions. Behavior of various sized particles inside the impactor was illustrated with the corresponding particle tracks. Fair agreement was obtained between code predictions and experimental results. Important information on the virtual impactor performance, not known earlier, or, not reported in the literature in the past, obtained from this study, is presented. In the final part of this study, simulations on aerosol deposition in turbulent pipe flow were performed. Code predictions were found to be completely uncorrelated to experimental data. The discrepancy was traced to the performance of the code's turbulent dispersion model. A detailed literature survey revealed the inherent technical deficiencies in the model, even for particle dispersion. Based on the results of this study, it was determined that while the code can be used for simulating aerosol transport under laminar flow conditions, it is not capable of simulating aerosol transport under turbulent flow conditions.
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Koren, Dejan. "Computational Fluid Dynamics Unstructured Mesh Optimization for the Siemens 4th Generation DLE Burner." Thesis, KTH, Mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-178034.
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Every computational fluid dynamics engineer deals with a never ending story – limitedcomputer resources. In computational fluid dynamics there is practically never enoughcomputer power. Limited computer resources lead to long calculation times which result inhigh costs and one of the main reasons is that large quantity of elements are needed in acomputational mesh in order to obtain accurate and reliable results.Although there exist established meshing approaches for the Siemens 4th generation DLEburner, mesh dependency has not been fully evaluated yet. The main goal of this work istherefore to better optimize accuracy versus cell count for this particular burner intended forsimulation of air/gas mixing where eddy-viscosity based turbulence models are employed.Ansys Fluent solver was used for all simulations in this work. For time effectivisationpurposes a 30° sector model of the burner was created and validated for the meshconvergence study. No steady state solutions were found for this case therefore timedependent simulations with time statistics sampling were employed. The mesh convergencestudy has shown that a coarse computational mesh in air casing of the burner does not affectflow conditions downstream where air/gas mixing process is taking place and that a majorpart of the combustion chamber is highly mesh independent. A large reduction of cell count inthose two parts is therefore allowed. On the other hand the RPL (Rich Pilot Lean) and thepilot burner turned out to be highly mesh density dependent. The RPL and the Pilot burnerneed to have significantly more refined mesh as it has been used so far with the establishedmeshing approaches. The mesh optimization has finally shown that at least as accurate resultsof air/gas mixing results may be obtained with 3x smaller cell count. Furthermore it has beenshown that significantly more accurate results may be obtained with 60% smaller cell count aswith the established meshing approaches.A short mesh study of the Siemens 3rd generation DLE burner in ignition stage of operationwas also performed in this work. This brief study has shown that the established meshingapproach for air/gas mixing purposes is sufficient for use with Ansys Fluent solver whilecertain differences were discovered when comparing the results obtained with Ansys Fluentagainst those obtained with Ansys CFX solver. Differences between Fluent and CFX solverwere briefly discussed in this work as identical simulation set up in both solvers producedslightly different results. Furthermore the obtained results suggest that Fluent solver is lessmesh dependent as CFX solver for this particular case.
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Björk, Johan. "Compressor CFD simulation method development : A CFD study." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-69880.
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This master thesis project consisted of three parts that all were performed through CFD simulations with the purpose to develop Scania's methods in the subject of CFD. All parts included simulations on Scania's SC92T70 centrifugal compressor. Part one consisted of performing a mesh study for the purpose of reliability, to investigate the convergence of different parameters by refining the boundary layer. The method used is an inflation option called First layer thickness. Five different meshes were generated where the Richardson extrapolation method was used to examine the parameters between the mesh renements. From the result from the examined parameters, an approximate relative error could be calculated to be less than 0.52 %, and a numerical uncertainty of less than 0.35 %, between Mesh3 and Mesh4. In addition to that, Mesh3 had a simulation time of one hour less than for Mesh4. These results motivated the use of mesh3 to be refined enough for further work in this thesis project. This mesh ended at 37, 915, 257 number of elements. The second part consisted of performing steady state CFD simulations, to examine different parameters in order to find indications of the phenomena surge. Here, experimental data was used as reliance to perform CFD simulations on the compressor. Design points from experimental data was used, that ranged from low mass flow rates where surge arises, to high mass flow rates where another phenomena called choke occur. Except for the design points taken from experimental data, a few extra design points where included at low mass flow rates (in the region of surge). The goal was that the analysis of the different parameters would generate fluctuations on the result for the design points in surge region. Four different rotational speeds on the compressor were examined, 56k, 69k, 87k and 110k revolutions per minute. A total of 140 different parameters were examined, where 10 of these indicated on surge. All of these parameters that indicated on surge where found in regions of vicinity to the compressor wheel, which are the regions subjected to the phenomena.The parameters indicating on surge where mass flow, pressure coefficient, static pressure and temperature. Indications where found at the wheel inlet, ported shroud, and wheel outlet interfaces. The indications were only found for the two lower rotational speeds of the compressor wheel. To capture the behaviour on higher rotational speeds, more design points in the region of surge are needed, or transient simulations. Part three of the thesis project consisted of investigating the methodology of performing a Conjugate Heat Transfer model (CHT) with the CFD code CFX. This part has not been performed by Scania before, so a big part of the problem was to investigate if it actually was achievable. The goal was to use this model to calculate the heat transfer between fluid and solid parts, as well as between the solid parts and the ambient. One question Scania wanted to answer was if the CHT model could generate aerodynamic performance that corresponds to Scania's traditional adiabatic model, as well as to experimental data of the compressor. In this part, both solid and fluid domains were included in the geometryto calculate heat transport, in contrast to the traditional adiabatic model that only uses the fluid domains. Because of that, a big part of the work consisted of defining all interfaces connecting together surfaces between all domains. This is needed to model heat transport between the domains. In the set up part in CFX, the CHT model differed a lot from the traditional adiabatic model in that way that the outer walls was not set up as adiabatic anymore. In the CHT model, instead heat transfer is allowed between the outer walls of the fluids and the solids. From the result simulations, one could see that the CHT model was able to compute the heat transfer between fluids and solids. It also managed to export thermal data such as heat flux and wall heat transfer coefficient to be used for mechanical analysis, which is an important part in Scania's work. From the analysis of aerodynamic performance, a conclusion was drawn that the CHT model was able to compute efficiency and pressure ratio that followed the behaviour ofthe traditional adiabatic model as well as experimental data. However, for lowermass flows, the CHT model started to underpredict which could be explained by the geometrical differences between the CHT and adiabatic model. By analysis of temperature, one could see quantitative differences compared to the traditional adiabatic model. For other parameters (static and total pressure), there were no experimental data to be used for comparison. Because of that, an important part in future work of this CHT method development is to perform more experimental test for CFD data to be compared against. Another important part to compare the models is to have an identical geometry. Without an identical geometry, deviations in result will occur that depends on geometry.
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Maher-Edwards, Lorraine. "The development of a questionnaire to assess metacognition in chronic fatigue syndrome/myalgic encephalomyelitis : the metacognitive beliefs in CFS/ME questionnaire (MB-CFQ)." Thesis, University of East London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533038.
Full textAbstract:
Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is characterised by persistent unexplained fatigue resulting in severe impairment in daily functioning. CFS-like illnesses have been reported as early as the 19`h century. The lack of a recognisable, organic cause has lead to the illness and diagnosis being steeped in controversy, with researchers and patients disagreeing on the name given to the illness, the absence of pathophysiology, the contribution of psychological/emotional factors and the effectiveness of treatments such as cognitive behaviour therapy (CBT). Despite this debate, CBT has been the most researched treatment, with an evidence base that has shown that CBT improves fatigue in some patients. However, the current CBT treatment has some weaknesses and a significant proportion of patients do not respond. One such weakness is that the current CBT treatment model may not sufficiently address rumination and attention which have been identified as potentially important features of CFS/ME. Little is known about the factors that might drive the use of these strategies and how they might relate to the various facets of the illness. It has been shown that perseverative thinking strategies, such as rumination and attentional hypervigilence, in anxiety and depression can be influenced by metacognitive beliefs (beliefs an individual holds about their thinking). It may therefore be of interest to investigate this in CFS/ME. The main aim of the research was to generate preliminary evidence that metacognitive beliefs play a role in CFS/ME. The role of rumination and attention were explored by looking at the metacognitive strategies that people with CFS/ME use and the metacognitive beliefs they hold about such strategies. The research was a mixed methods design and consisted of a series of studies concerned with the development and validation of a questionnaire to measure metacognitive beliefs in CFS/ME (MB-CFQ): 1) a thematic analysis was conducted on transcripts from 10 semi-structured interviews with CFS/ME patients; 2) the results of the thematic analysis were used to design a questionnaire which was piloted in 104 CFS/ME patients and a principal components analysis was conducted; and. 3) a correlation analysis was conducted to provide some preliminary validation. The MB-CFQ showed high internal consistency and preliminary evidence of concurrent and construct validity. The questionnaire was used to investigate relationships between fatigue, metacognition and low mood. The data showed that, in CFS/ME, holding positive and negative metacognitive beliefs about the use of perseverative thinking strategies, including worry, rumination, and body monitoring (negative beliefs only), related positively to levels of fatigue (in particular mental fatigue), depression, stress, and anxiety. The results of this exploratory study now require further research to disentangle this observed relationship between metacognition, fatigue and mood.
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King, C. M. "The role of resting Ca2+ in astrocyte Ca2+ signalling." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1474498/.
Full textAbstract:
Astrocytes form gap-junction coupled networks and their fine processes cover many synapses enabling astrocytes to powerfully modulate synapse function. Such modulation is thought to involve Ca2+ -dependent release of signalling molecules from astrocytes. However, astrocyte Ca2+ signalling and its role in synaptic physiology remains a matter of debate. An incomplete and mostly qualitative understanding of the fundamental mechanisms of intracellular Ca2+ signalling in astrocytes could be a knowledge-limiting factor. Previous studies predict that astrocyte resting [Ca2+] profoundly affects astrocyte Ca2+ signalling, especially IP3 and store-dependent Ca2+ transients. I therefore quantitatively investigated the role of resting [Ca2+] in shaping spontaneous and evoked Ca2+ transients in astrocytes. I used two-photon excitation fluorescence microscopy and whole-cell patch clamp to document Ca2+ signalling of individual passive astrocytes in the CA1 stratum radiatum of acute hippocampal slices in young adult rat. I used fluorescence lifetime imaging to obtain a quantitative readout of astrocyte [Ca2+] and reveal the relationship between resting [Ca2+] and Ca2+ transients. I combined these techniques with UV-uncaging of Ca2+ or Ca2+ buffer to manipulate the astrocyte resting [Ca2+] to further investigate its effect on Ca2+ signalling. Using these methods, we have found that low resting [Ca2+] were associated with smaller amplitudes of spontaneous Ca2+ transients. This was also true for metabotropic glutamate receptor agonist (DHPG) evoked Ca2+ transients when different cells or regions of interest of the same cell were compared. The well-established increase of most IP3 receptors’ open probability at higher cytosolic [Ca2+] could explain this observation. In contrast, changes of resting [Ca2+] within a single astrocyte region were associated with inverse changes in amplitude of evoked Ca2+ transients. The DHPG-induced equilibration of [Ca2+] across cytosol and store compartments could be a potential explanation for this effect. Thus, resting [Ca2+] could shape the amplitude of astrocyte Ca2+ transients by at least two distinct mechanisms.
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Heinz, Pavel. "Vstupní recirkulace u odstředivého čerpadla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416449.
Full textAbstract:
This diploma thesis deals with the phenomenon appearing in hydrodynamic pumps at the sub-optimal flow rate. This phenomenon is inlet recirculation, which is an undesirable phenomenon in the suction of the pump. This recirculation causes cavitation, pressure pulsations and may cause clogging of the suction line. The main goal of the diploma thesis is CFD simulation for the recirculation mode, identification of the flow phenomena, and designs of possible measures to suppress inlet recirculation.
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Zeileis, Achim, Friedrich Leisch, Christian Kleiber, and Kurt Hornik. "Monitoring structural change in dynamic econometric models." SFB Adaptive Information Systems and Modelling in Economics and Management Science, WU Vienna University of Economics and Business, 2002. http://epub.wu.ac.at/1296/1/document.pdf.
Full textAbstract:
The classical approach to testing for structural change employs retrospective tests using a historical data set of a given length. Here we consider a wide array of fluctuation-type tests in a monitoring situation - given a history period for which a regression relationship is known to be stable, we test whether incoming data are consistent with the previously established relationship. Procedures based on estimates of the regression coefficients are extended in three directions: we introduce (a) procedures based on OLS residuals, (b) rescaled statistics and (c) alternative asymptotic boundaries. Compared to the existing tests our extensions offer better power against certain alternatives, improved size in finite samples for dynamic models and ease of computation respectively. We apply our methods to two data sets, German M1 money demand and U.S. labor productivity.Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
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Ghislat, Cherfaoui Ghita. "Regulation of Lysosomal Degradation by CA2+And CA2+-Binding Proteins." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/29690.
Full textAbstract:
La macroautofagia y la endocitosis son dos procesos catabólicos
conservados evolutivamente en los que, mediante un tráfico vesicular, se
degrada el material secuestrado, cuyo origen es intra- y extracelular,
respectivamente. Ambos procesos comienzan de manera diferente:
mediante la formación de un nuevo orgánulo, el autofagosoma, que
secuestra material citoplásmico (macroautofagia), o mediante la
internalización de material extracelular y de algunos componentes de la
membrana plasmática a través de vesículas endocíticas (endocitosis). Sin
embargo, los dos terminan en el mismo compartimiento: el lisosoma.
En un análisis proteómico de membranas lisosomales, purificadas a
partir de fibroblastos de ratón, identificamos tres proteínas, que se unen a
fosfolípidos de una manera dependiente de calcio, y cuyos niveles en la
membrana lisosomal aumentaban en ausencia de aminoácidos, una
condición que activa la macroautofagia. Basándonos en esos resultados
iniciales, y teniendo en cuenta que el calcio es un segundo mensajero muy
importante, decidimos: en primer lugar, abordar el papel del calcio en la
activación de la autofagia producida por el ayuno de aminoácidos, y, en
segundo lugar, investigar el papel de esas tres proteínas en el mecanismo
autofágico.
Como resultado de estos estudios, describimos en primer lugar una
nueva vía de señalización dependiente de calcio que activa la formación de
autofagosomas por los aminoácidos. Concretamente, hemos encontrado
que el ayuno de aminoácidos esenciales produce un aumento en el calcio
citosólico, procedente tanto del medio extracelular como de almacenes
intracelulares. Como consecuencia de esto, la calmodulina quinasa quinasa-
ß activa a AMPK y a mTORC1. En la última etapa de esta vía, ULK1, una
quinasa responsable de la iniciación de la autofagia, se activa para
contribuir a la formación de los autofagosomas.
Las tres proteínas identificadas en el estudio proteómico y cuyos
niveles en las membranas lisosomales aumentan en ausencia de aminoácidos son la anexina A1, la anexina A5 y la copina 1. Empleando
métodos bioquímicos y de inmunofluorescencia observamos que el ayuno
de aminoácidos causa la translocación de la anexina A5 desde el complejo
de Golgi hasta las membranas lisosomales, donde también se acumulan la
anexina A1 y la copina 1. Asimismo, demostramos por sobre-expresión y
silenciamiento de esas tres proteínas, que las tres inducen la fusión de
autofagosomas con lisosomas y que la copina 1, y en menor medida la
anexina A1, aumentan el efecto individual de la anexina A5. Finalmente, la
anexina A5 inhibe la endocitosis mientras que copina 1 la induce.
En resumen, nuestros resultados ponen de manifiesto que la
activación de la formación de autofagosomas por el ayuno de aminoácidos
es debida, al menos en parte, a una vía de señalización dependiente de
Ca2+
y que esta condición también conlleva la aceleración de la maduración
de los autofagosomas a autolisosomas a través de proteínas que unen el
Ca2+ como las anexinas A1 y A5 y la copina 1.Ghislat Cherfaoui, G. (2013). Regulation of Lysosomal Degradation by CA2+And CA2+-Binding Proteins [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/29690
TESIS
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Du, Jianyi. "Combustion CFD simulation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/NQ56437.pdf.
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Bergmann, Cale. "Comparison of turbulence model predictions in rod bundles with supercritical up-flow." VTT Technical Research Centre of Finland Ltd, 2015. http://hdl.handle.net/1993/31016.
Full textAbstract:
Vertical up-flow of supercritical fluid in the subchannel of a heated rod bundle was numerically simulated using the Computational Fluid Dynamics (CFD) codes ANSYS CFX and ANSYS FLUENT. A total of seven cases from three different sets of experiments were simulated. Three-dimensional steady-state predictions of fluid velocity, pressure, and temperature were made using five versions of two-equation RANS turbulence models with accompanying wall treatments. In addition, the temperature distribution in a solid region comprising a heater and sheathing was also computed in some cases.
The k-epsilon turbulence model, implemented using CFX and scalable wall functions, provided the numerical results that have the smallest overall deviation from experimental results for three of the seven cases, and predicts the experimental data of the remaining four cases reasonably well, unlike other turbulence models that severely over-predict the experimental data for wall surface temperature.February 2016
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Miazhynskaia, Tatiana, Engelbert J. Dockner, and Georg Dorffner. "On the economic costs of value at risk forecasts." SFB Adaptive Information Systems and Modelling in Economics and Management Science, WU Vienna University of Economics and Business, 2003. http://epub.wu.ac.at/190/1/document.pdf.
Full textAbstract:
We specify a class of non-linear and non-Gaussian models for which we estimate and forecast the conditional distributions with daily frequency. We use these forecasts to calculate VaR measures for three different equity markets (US, GB and Japan). These forecasts are evaluated on the basis of different statistical performance measures as well as on the basis of their economic costs that go along with the forecasted capital requirements. The results indicate that different performance measures generate different rankings of the models even within one financial market. We also find that for the three markets the improvement in the forecast by non-linear models over linear ones is negligible, while non-gaussian models significantly dominate the gaussian models.Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
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Novák, Ondřej. "Aerodynamická analýza protipumpážních úprav turbovrtulového motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443213.
Full textAbstract:
Tahle práce se zaměřila na aerodynamickou analýzu principů zvyšování pumpážních záloh. V první kapitole jsou popsány kompresory leteckých motorů a zavedeny potřebné znalosti kompresorových charakteristik a proti-pumpážních zařízení. V druhé kapitole se nachází detailní popis CFD modelu, jeho nastavení, citlivostní analýzy sítě a korelace výsledků s experimentálním měřením. V třetí kapitole jsou popsány data neupraveného kompresoru a jsou zde popsány problematická místa první stupně kompresoru z pohledu proti-pumpážních zařízení. Ve čtvrté kaptiole jsou popsány CFD výsledky z analýz jednotlivých proti-pumpážních zařízení a také popis jejich optimalizace. Práce je zakončena srovnáním jednotlivých zařízení pomocí dvou objektivních kritérií.
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Haase, Andreas. "Untersuchungen zur Kinetik des Ca2+-aktivierten Chloridkanals und des Na+-Ca2+-Austauschers." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968360688.
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Broad, L. M. "Regulation of Ca2+ entry and Ca2+ efflux in smooth muscle cell lines." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596924.
Full textAbstract:
In many cells, agonists that stimulate formation of inositol 1,4,5-trisphosphate (IP3) mobilise intracellular Ca2+ stores and activate several Ca2+ transport pathways in the plasma membrane. This thesis addresses the characteristics and regulation of these hormone-activated Ca2+ transport pathways in Fura 2-loaded vascular smooth muscle cell lines. The effect of cellular differentiation on the capacitative Ca2+ entry pathway in BC3Hl cells was studied using thapsigargin to empty the intracellular Ca2+ stores. Undifferentiated BC3H1 cells exhibited Ca2+ mobilisation in response to IP3 only, whereas differentiated cells responded to IP3, or to caffeine and ryanodine. Although both differentiated and undifferentiated cells expressed a capacitative Ca2+ entry pathway, the bivalent cation selectivity of the pathways differed. In undifferentiated cells, large capacitative Ca2+ entry signals were accompanied by relatively small Mn2+ and Ba2+ entry signals; the converse was true of differentiated cells. The relative increase in Mn2+ and Ba2+ permeability in differentiated cells was not a consequence of more active Ca2+ extrusion. The change in behaviour of the pathway after differentiation may result either from expression of a different capacitative pathway or from modification of the permeation properties of a single pathway. Stimulation of a7r5 cells with arginine-vasopressin (AVP) activated both a capacitative and non-capacitative Ca2+ entry pathway in the plasma membrane, only the latter was permeable to Sr2+. AVP also stimulated Ca2+ removal from the cytoplasm. The ability of other receptors that stimulate phosphoinositidase C to activate the non-capacitative pathway, its susceptibility to inhibition by a PIC inhibitor (U73122), and the similar sensitivities of Ca2+ release and Sr2+ entry to AVP suggested a close coupling between stimulation of PIC and activation of this pathway. This work has revealed that Ca2+ mobilisation, multiple capacitative and non-capacitative Ca2+ entry pathways and Ca2+ efflux all contribute to the complexity of receptor-activated Ca2+ signalling.
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Lax, Pérez Antonio Manuel. "Ca2+-ATPasa y Muerte Celular Inducida por Ca2+ en células Cardíacas H9c2." Doctoral thesis, Universidad de Murcia, 2009. http://hdl.handle.net/10803/285677.
Full textAbstract:
La Ca2+-ATPasa de RS puede hidrolizar ATP a través de una ruta alternativa en la que solo intervienen conformaciones de la proteína que no unen Ca2+. El mecanismo molecular de esta actividad hidrolítica implica un cambio conformacional inducido por ATP que produce aproximaciones de los dominios citosólicos. El uso de indicadores fluorescentes y compuestos que movilizan Ca2+ permite caracterizar flujos y depósitos intracelulares de Ca2+ que están implicados en la generación de señales intracelulares de Ca2+ en células H9c2. La mitocondria es capaz de interpretar señales citosólicas de Ca2+ que se generan en el retículo sarco-endoplásmico (RSE). El efecto apoptótico que se observa en presencia del inhibidor Tapsigargina (TG) es dependiente de la concentración usada. La muerte celular se produce antes cuando TG provoca apertura del poro de permeabilidad transitoria mitocondrial. El daño producido en el RSE activa la ruta apoptótica mitocondrial con participación de cas
pasa 8 en un lazo que amplifica la cascada degradativa de las caspasas. Las células disponen de mecanismos alternativos de muerte celular en los que no participan caspasas.
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Nunes, Bonaventure R. "Numerical Loss Prediction of high Pressure Steam Turbine airfoils." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51742.
Full textAbstract:
Steam turbines are widely used in various industrial applications, primarily for power extraction. However, deviation for operating design conditions is a frequent occurrence for such machines, and therefore, understanding their performance at off design conditions is critical to ensure that the needs of the power demanding systems are met as well as ensuring safe operation of the steam turbines. In this thesis, the aerodynamic performance of three different turbine airfoil sections ( baseline, mid radius and tip profile) as a function of angle of incidence and exit Mach numbers, is numerically computed at 0.3 axial chords downstream of the trailing edge. It was found that the average loss coefficient was low, owing to the fact that the flow over the airfoils was well behaved. The loss coefficient also showed a slight decrease with exit Mach number for all three profiles. The mid radius and tip profiles showed near identical performance due to similarity in their geometries. It was also found out that the baseline profile showed a trend of substantial increase in losses at positive incidences, due to the development of an adverse pressure zone on the blade suction side surface. The mid radius profile showed high insensitivity to angle of incidence as well as low exit flow angle deviation in comparison to the baseline blade.Master of Science
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Höhne, Thomas. "Kühlmittelvermischung in Druckwasserreaktoren; Vergleich von Kühlmittelströmung und -vermischung in einem skalierten Modell des DWR Konvoi mit den Vorgängen im Originalreaktor; Rechnungen mit dem CFD-Code CFX 4.1." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-30848.
Full textAbstract:
Es ergab sich die Notwendigkeit, die Vermischungseffekte mit einem 1:5 skalierten Modell nachzuvollziehen. In dieser Arbeit wurden Skalierungseffekte hervorgehoben und ein Vergleich der Strömungen im Originalreaktor und 1:5 Plexiglasmodell mit Hilfe eines numerischen Strömungsberechnungsprogrammes vollzogen. Dabei wurde das Modell und der Originalreaktor möglichtst originalgetreu abgebildet und mit den kalten Strängen zusammen modelliert.Die Vergleichsrechnungen belegen, daß es ausreichend ist, die Vermischungsvorgänge in einem mindestens 1:6.6 skalierten Modell eines DWR zu untersuchen. Die Parameter (Druck, Temperatur, Geschwindigkeit) erlauben den Aufbau als Plexiglasmodell, das eine optische Beobachtung der Vermischung ermöglicht. Das Forschungszentrum Rossendorf hat mit dem Aufbau eines 1:5 Modells 1997 begonnen.
37
Höhne, Thomas. "Kühlmittelvermischung in Druckwasserreaktoren; Vergleich von Kühlmittelströmung und -vermischung in einem skalierten Modell des DWR Konvoi mit den Vorgängen im Originalreaktor; Rechnungen mit dem CFD-Code CFX 4.1." Forschungszentrum Rossendorf, 1997. https://hzdr.qucosa.de/id/qucosa%3A21911.
Full textAbstract:
Es ergab sich die Notwendigkeit, die Vermischungseffekte mit einem 1:5 skalierten Modell nachzuvollziehen. In dieser Arbeit wurden Skalierungseffekte hervorgehoben und ein Vergleich der Strömungen im Originalreaktor und 1:5 Plexiglasmodell mit Hilfe eines numerischen Strömungsberechnungsprogrammes vollzogen. Dabei wurde das Modell und der Originalreaktor möglichtst originalgetreu abgebildet und mit den kalten Strängen zusammen modelliert.Die Vergleichsrechnungen belegen, daß es ausreichend ist, die Vermischungsvorgänge in einem mindestens 1:6.6 skalierten Modell eines DWR zu untersuchen. Die Parameter (Druck, Temperatur, Geschwindigkeit) erlauben den Aufbau als Plexiglasmodell, das eine optische Beobachtung der Vermischung ermöglicht. Das Forschungszentrum Rossendorf hat mit dem Aufbau eines 1:5 Modells 1997 begonnen.
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Barisch-Dick, Susanne. "Aspects of AdS / CFT." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-158390.
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Gilani, Mohammad Nejad Hamzeei. "CFD of droplet entrainment." Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542939.
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Shah, Akhil Rajesh. "Topics in AdS/CFT." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1835420801&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Huh, Dongsung 1981. "Ca2+ dependant synaptic modification." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32741.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2004.Includes bibliographical references (p. 21-22).
It has been assumed that Ca2+ influx of different duration and amplitude would generate different level of potentiation. The conventional protocols of generating LTP have been 1. tetanic stimulation of presynaptic cell, 2. theta burst stimulation of presynaptic cell, and 3. correlated stimulation of pre- and post-synaptic cells. However, the effects of different Ca2+ influx can not be precisely dissected with the conventional protocols for the following defects: 1. the protocols do not discriminate between pre- and post-synaptic side plasticity, 2. the protocols observe synaptic plasticity between two cells which involve multiple synapses with heterogeneous properties, 3. precise control and measurement of the amount of Ca2+ influx are not possible in the protocols. In the present experiment, we perfused glutamate directly on to a single postsynaptic site, depolarized the postsynaptic intracellular potential to a controlled voltage for a controlled duration of time, thus controlling the opening of postsynaptic NMDA receptors and Ca2+ influx. By using this method, we found 1. that modification of synaptic strength has a bell-shaped dependency to the amount of Ca2+ influx, 2. that weak Ca2+ current through desensitized NMDA receptors sustained for a long period of time (160 ms) generates LTD, 3. evidence that phosphorylation of AMPAR leads to insertion of AMPAR.
by Dongsung Huh.
S.B.
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Heinz, Matthias. "CFD- Berechnung von Axialkolbenpumpen." Technische Universität Chemnitz, 2019. https://monarch.qucosa.de/id/qucosa%3A34344.
Full textAbstract:
Axialkolbenpumpen bieten eine hohe Leistungsdichten und einfache Regelbarkeit.
Allerdings neigen sie zu Kavitation, mit der Gefahr der Beschädigung und erhöhter Geräuschbildung durch Druckpulsationen. Die numerische Strömungssimulation bietet die Möglichkeit, die transienten Prozesse innerhalb dieser Pumpen zu verstehen und Optimierungsmöglichkeiten aufzuzeigen.
Die komplexe Bewegung der Kolben erfordert bewegte Gitter, die translatorische und rotatorische Bewegungen sehr genau abbilden müssen. Die zu fördernde Hydraulikflüssigkeit muss als kompressibles Medium behandelt werden, insbesondere da sie zu bestimmten Zeiten (Kompressions- und Dekompressionsphase) in geschlossen Kammern einer Volumenänderung unterworfen ist, die eine Dichte- und Druckänderung mit sich bringt. Im Falle des Auftretens von Kavitation ist eine Modellierung der gasförmigen und flüssigen Phase notwendig.
Der Vortrag zeigt auf, wie das vollständige transiente Verhalten von Axialkolbenpumpen simuliert werden kann. Dadurch ist es möglich, Steuerzeitenoptimierungen durchzuführen, die zu geringerer Kavitationsneigung und reduzierten Druckpulsationen führen.
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Augusto, Arias Vernal Carlos. "Cfa Workshop-AF124-201702." Universidad Peruana de Ciencias Aplicadas (UPC), 2017. http://hdl.handle.net/10757/628606.
Full textAbstract:
CFA Workshop es un curso de especialidad de la carrera de Administración y Finanzas de carácter teórico-práctico dirigido a los estudiantes de décimo ciclo que busca desarrollar la competencia de "Evaluación de alternativas de inversión y financiamiento y gestión integral de riesgos" al nivel 3.En al ámbito financiero internacional contar con la mención Chartered Financial Analyst (CFA) es un sinónimo de excelencia académica y profesional. Inversionistas y empleadores en todo el mundo utilizan esta certificación como un estándar para medir la integridad y competencia en las áreas de análisis de inversiones y administración de portafolios.La designación CFA requiere que sus candidatos demuestren un conocimiento estricto del currículo que abarca diferentes campos relacionados con las finanzas y las inversiones. Esta certificación se otorga a los candidatos después de aprobar los exámenes correspondientes a los niveles I II y III y demostrar una destacada experiencia laboral. Los tres niveles del examen CFA son ofrecidos en Junio de cada ano en más de 150 ciudades alrededor del mundo entre ellas Lima. En el Perú la Superintendencia de Banca y Seguros (SBS) publicó en el 2005 un marco normativo para asegurar un manejo más eficiente y profesional de los recursos que administran las entidades financieras las compañías de seguros y las administradoras de fondos de pensiones (AFP).El curso "CFA Workshop" pretende exponer en forma útil y práctica los conceptos criterios y herramientas de análisis y gestión de inversiones que le permitan al candidato al examen CFA Nivel I desarrollar las habilidades y estrategias necesarias para su práctica profesional y el logro con éxito de la certificación de analista financiero.
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Martin, Gomez Sanchez Arbulu Alvaro, and Arias Vernal Carlos Augusto. "Cfa Workshop-AF124-201802." Universidad Peruana de Ciencias Aplicadas (UPC), 2018. http://hdl.handle.net/10757/628608.
Full textAbstract:
CFA Workshop es un curso de especialidad de la carrera de Administración y Finanzas de carácter teórico-práctico dirigido a los estudiantes de décimo ciclo.En al ámbito financiero internacional contar con la mención Chartered Financial Analyst (CFA) es un sinónimo de excelencia académica y profesional. Inversionistas y empleadores en todo el mundo utilizan esta certificación como un estándar para medir la integridad y competencia en las áreas de análisis de inversiones y administración de portafolios.La designación CFA requiere que sus candidatos demuestren un conocimiento estricto del currículo que abarca diferentes campos relacionados con las finanzas y las inversiones. Esta certificación se otorga a los candidatos después de aprobar los exámenes correspondientes a los niveles I II y III y demostrar una destacada experiencia laboral. Los tres niveles del examen CFA son ofrecidos en Junio de cada ano en más de 150 ciudades alrededor del mundo entre ellas Lima. En el Perú la Superintendencia de Banca y Seguros (SBS) publicó en el 2005 un marco normativo para asegurar un manejo más eficiente y profesional de los recursos que administran las entidades financieras las compañías de seguros y las administradoras de fondos de pensiones (AFP).El curso "CFA Workshop" pretende exponer en forma útil y práctica los conceptos criterios y herramientas de análisis y gestión de inversiones que le permitan al candidato al examen CFA Nivel I desarrollar las habilidades y estrategias necesarias para su práctica profesional y el logro con éxito de la certificación de analista financiero.
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Martin, Gomez Sanchez Arbulu Alvaro, and Arias Vernal Carlos Augusto. "Cfa Workshop-AF124-201801." Universidad Peruana de Ciencias Aplicadas (UPC), 2018. http://hdl.handle.net/10757/628607.
Full textAbstract:
CFA Workshop es un curso de especialidad de la carrera de Administración y Finanzas de carácter teórico-práctico dirigido a los estudiantes de décimo ciclo que busca desarrollar la competencia de "Evaluación de alternativas de inversión y financiamiento y gestión integral de riesgos" al nivel 3.En al ámbito financiero internacional contar con la mención Chartered Financial Analyst (CFA) es un sinónimo de excelencia académica y profesional. Inversionistas y empleadores en todo el mundo utilizan esta certificación como un estándar para medir la integridad y competencia en las áreas de análisis de inversiones y administración de portafolios.La designación CFA requiere que sus candidatos demuestren un conocimiento estricto del currículo que abarca diferentes campos relacionados con las finanzas y las inversiones. Esta certificación se otorga a los candidatos después de aprobar los exámenes correspondientes a los niveles I II y III y demostrar una destacada experiencia laboral. Los tres niveles del examen CFA son ofrecidos en Junio de cada ano en más de 150 ciudades alrededor del mundo entre ellas Lima. En el Perú la Superintendencia de Banca y Seguros (SBS) publicó en el 2005 un marco normativo para asegurar un manejo más eficiente y profesional de los recursos que administran las entidades financieras las compañías de seguros y las administradoras de fondos de pensiones (AFP).El curso "CFA Workshop" pretende exponer en forma útil y práctica los conceptos criterios y herramientas de análisis y gestión de inversiones que le permitan al candidato al examen CFA Nivel I desarrollar las habilidades y estrategias necesarias para su práctica profesional y el logro con éxito de la certificación de analista financiero.
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Martin, Gomez Sanchez Arbulu Alvaro, and Arias Vernal Carlos Augusto. "Cfa Workshop-AF124-201901." Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/628609.
Full textAbstract:
CFA Workshop es un curso de especialidad de la carrera de Administración y Finanzas de carácter teórico-práctico dirigido a los estudiantes de décimo ciclo.En al ámbito financiero internacional contar con la mención Chartered Financial Analyst (CFA) es un sinónimo de excelencia académica y profesional. Inversionistas y empleadores en todo el mundo utilizan esta certificación como un estándar para medir la integridad y competencia en las áreas de análisis de inversiones y administración de portafolios.La designación CFA requiere que sus candidatos demuestren un conocimiento estricto del currículo que abarca diferentes campos relacionados con las finanzas y las inversiones. Esta certificación se otorga a los candidatos después de aprobar los exámenes correspondientes a los niveles I II y III y demostrar una destacada experiencia laboral. Los tres niveles del examen CFA son ofrecidos en Junio de cada ano en más de 150 ciudades alrededor del mundo entre ellas Lima. En el Perú la Superintendencia de Banca y Seguros (SBS) publicó en el 2005 un marco normativo para asegurar un manejo más eficiente y profesional de los recursos que administran las entidades financieras las compañías de seguros y las administradoras de fondos de pensiones (AFP).El curso "CFA Workshop" pretende exponer en forma útil y práctica los conceptos criterios y herramientas de análisis y gestión de inversiones que le permitan al candidato al examen CFA Nivel I desarrollar las habilidades y estrategias necesarias para su práctica profesional y el logro con éxito de la certificación de analista financiero.
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Collins, Tessa Lee, and Tessa Lee Collins. "CFA Institute Research Challenge." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/624947.
Full textAbstract:
As a group of finance students, we were tasked with valuing Western Alliance Bancorporation for the CFA Institute Research Challenge. The competition required us to submit an analyst report detailing our research and findings about the company. Through our research and analysis, we found a stock price of $41.36, which was below their trading price, which resulted in a "sell" decision for Western Alliance Bancorporation (WAL: NYSE). Using a combination of background research on the company, industry and financial analysis and valuation techniques. Western Alliance Bancorporation is a smaller regional bank that with the current market environment for banks, the current political instability and the competitive nature of the banking industry was determined to not be outperforming and carries a lot of risk. When looking at their financials, we determined that they had a fairly small market capitalization and was trading at high multiples for the industry. Using several valuation techniques and building the model, looking at historical pricing and residuals we came to the sell decision. Ultimately, we were able to submit our analyst report, but were not chosen to continue on to the local competition. This was a great learning experience and we were able to learn a lot about the environment in this industry.
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ARCHIBALD, MARIE ALEXANDRA, LAUREN PAIGE HOEPFNER, FABIO ANDRE MIRE, ACACIA MARIE MOORE, and JESSICA JANE SCHULTE. "CFA INSTITUTE RESEARCH CHALLENGE." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613074.
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SCHULTE, JESSICA JANE. "CFA INSTITUTE RESEARCH CHALLENGE." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/614166.
Full textAbstract:
A traditional part of the portfolio management course at the University of Arizona's Eller College of Management, is that each year a team participates in the international CFA Institute Research Challenge. This challenge is an annual competition that permits university students around the world to gain intensive training and practice in financial analysis. Students work in teams of 4 or 5 over the course of a semester to research and analyze a publically traded company. This year we, along with all other schools participating in this competition were asked to value Sprouts. Being from the Southwest region, we and four other teams were further afforded the opportunity to speak with the CFO of Sprouts in addition to conducting our own research. Utilizing all the resources provided to us, we proceeded to develop a 10-page recommendation regarding our position on Sprouts' stock: buy, sell or hold. This competition culminated for our team in a verbal presentation given to a local panel of CFA Institute members which, when combined with our report score, afforded us second place.
The remainder of this thesis report details the research and work involved in producing both the 10-page report and the presentation for this challenge.
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Wisnoskey, Brian J. "Role of Ca2+ -permeable cation channels in Ca2+ Signalling and necrotic cell death." Connect to online version, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1085624581.
Full textAbstract:
Thesis (Ph. D.)--Case Western Reserve University, 2004.[School of Medicine] Department of Physiology and Biophysics. Includes bibliographical references. Available online via OhioLINK's ETD Center.