Global ETD Search

31	Contribution à létude du peptide de fusion et du domaine transmembranaire des glycoprotéines de fusion virales de classe 1 / Contribution to the study of the fusion peptide and the transmembrane domain of class 1 viral fusion glycoproteins Lorin, Aurélien 09 October 2007 (has links) Les glycoprotéines de fusion virales de classe 1 contrôlent la fusion entre lenveloppe virale et la membrane cellulaire. Ces glycoprotéines présentent une extrémité N-terminale indispensable à la fusion, le peptide de fusion. Les peptides de fusion sont capables dinduire à eux seuls la fusion de membranes in vitro. Dans cette étude, nous avons dabord analysé les peptides de fusion de gp41 du HIV et de gp30 du BLV. Ces deux peptides de fusion sont des peptides obliques : ils sinsèrent obliquement dans la membrane sous forme hélicoïdale. Nos études ont montré une relation entre la capacité de ces deux peptides de fusion à sinsérer obliquement dans la membrane et la capacité de leurs glycoprotéines de fusion à induire la fusion. Dans le cas du BLV, nous avons également montré une relation entre lobliquité du peptide de fusion et sa fusogénicité. Cette relation obliquité-fusogénicité a été utilisée pour prédire avec succès la région minimale des deux peptides de fusion suffisante pour induire une fusion significative in vitro, qui correspond respectivement aux douze et aux quinze premiers acides aminés de gp41 et gp30. Nos résultats montrent également que le peptide caméléon, un peptide de novo avec une structure labile, sinsère obliquement dans la membrane et induit la fusion in vitro. Le fait que ce peptide fasse partie des peptides obliques, comme les peptides de fusion du HIV et BLV, renforce lhypothèse dun lien entre la fusogénicité des peptides de fusion et leur flexibilité structurale. De nombreuses études réalisées sur les glycoprotéines de fusion de classe 1 indiquent que le domaine transmembranaire intervient également dans la fusion virale. Ce domaine doit être suffisamment long pour que la fusion soit complète. Dans ce travail, nous avons montré quun peptide transmembranaire modèle, le peptide KALR, est capable de sinsérer et dinduire la fusion de liposomes in vitro. En comparant les résultats de modélisation moléculaire avec ceux de FTIR et ceux de la fusion de phase lipidique/perméabilisation de liposomes, nous avons également montré que le taux dinsertion membranaire et la fusogénicité de KALR dépendent de la longueur de son cur hydrophobe. En effet, le taux dinsertion de KALR dans la membrane est beaucoup plus important lorsquil contient un cur hydrophobe lui permettant de traverser entièrement la membrane. Dans cette situation, KALR est capable dinduire la déstabilisation et la fusion de membranes alors que lorsque son cur hydrophobe est trop court pour lui permettre de traverser la membrane, il en est incapable. Ces résultats ont permis dapporter des éléments de compréhension des mécanismes intervenant lors de la fusion induite par les glycoprotéines de fusion virales. / Abstract: Class 1 fusion glycoproteins of viruses are involved in the fusion between viral envelope and cell membrane. The N-terminal extremity of these glycoproteins, called fusion peptide, is essential for fusion. Fusion peptides are able to induce by themselves in vitro membrane fusion. Firstly, we analysed fusion peptides of HIV-1 gp41 and BLV gp30. These two peptides are tilted peptides: they insert obliquely in the membrane when helical. Our studies showed a correlation between the ability of these two fusion peptides to insert obliquely in the membrane and the ability of whole glycoproteins to induce fusion. For BLV, a relationship between the obliquity of the fusion peptide and its fusogenicity was also observed. This obliquity/fusogenicity relationship was used to successfully predict the minimal region of the two fusion peptides sufficient to induce significant in vitro fusion. The minimal fusion peptide corresponds respectively to the twelve and to the fifteen first residues of gp41 and gp30. Our results also showed that the chameleon peptide, a de novo peptide with structural flexibility, inserts obliquely into the membrane and induces in vitro fusion. The fact that this peptide is a tilted peptide, like fusion peptides of HIV-1 and BLV, confirms the hypothesis of a relationship between the fusion peptides fusogenicity and their structural flexibility. A lot of studies on class 1 fusion glycoproteins of viruses indicate that the transmembrane domain is also directly involved in the viral fusion. Glycoproteins must have a domain long enough to induce complete fusion. In this study, we showed that a model transmembrane peptide, KALR peptide, is able to insert into membranes and to induce their fusion. By comparing molecular modelling results with those of FTIR, of liposomes lipid-mixing and of liposomes leakage, we also showed that the insertion rate into the membranes and the fusogenicity of KALR depend on the length of its hydrophobic core. Indeed, the insertion rate of KALR into the membrane is greatly larger when it contains a hydrophobic core long enough to allow the peptide to traverse the membrane. In this situation, KALR is able to destabilize membranes and to induce their fusion, while when it is too short to match the membrane, it is unable to induce fusion. These results allow to better understanding mechanisms involved in the fusion induced by viral fusion glycoproteins. infrarouge/infrared liposome/liposome bioinformatique/bioninformatics permeabilite/leakage biophysique/biophysics VIH/HIV LBV/BLV virus enveloppe/enveloped virus SARS/SRAS Influenza A/Influenza A fusion membranaire/membrane fusion peptide oblique/tilted peptide melange lipidique/lipid-mixing ATR-FTIR/ATR-FTIR hydrophobicite/hydrophobicity
32	Entwicklung und Modellierung einer vollaktuierten Drohne / Developement and modelling of a fully actuated flight robot Schuster, Micha 02 July 2018 (has links) (PDF) Diese Diplomarbeit beschäftigt sich mit der geometrischen Auslegung und Regelung einer vollaktuierten Drohne, die als fliegende Arbeitsplattform für einen Manipulator dienen soll. Dabei werden ausgehend von der geometrischen Beschreibung einer allgemeinen, symmetrischen Drohne mit sechs Rotoren Methoden entwickelt, die den anforderungsbezogenen Entwurf der Geometrie einer vollaktuierten Drohne ermöglichen. Darüber hinaus werden prinzipielle Einflussmechanismen einzelner Geometrieparameter auf die durch die Drohne erzeugbaren Kräfte und Momente aufgezeigt. Zur Charakterisierung des Raums aller erzeugbaren Lasten wird dieser auf sogenannte Stützvektoren reduziert. Als Stützvektoren dienen dabei die für den Schwebeflug nötige Schubkraft, die garantierte Mindestkraft in horizontaler Richtung und das garantierte Mindestmoment um eine beliebige Achse, zu deren Berechnung zusätzlich analytische Formeln hergeleitet werden. Aufbauend auf die Beschreibung durch Stützvektoren wird die Formuliernung von Metriken vorgestellt, die die Bewertung einer Drohnengeometrie durch eine einzige skalare Maßzahl ermöglichen, wodurch die je nach Anwendung optimale Drohnengeometrie ermittelt werden kann. Zur Regelung des Systems aus Drohne und Manipulator wurde ein Regelungskonzept entwickelt, welches durch eine Entkopplung der Bewegungsgleichungen eine virtuelle Verschiebung des Schwerpunkts in das Drohnenzentrum realisiert und so eine präzise Regelung unabhängig von der tatsächlichen Schwerpunktlage ermöglicht. / This thesis’ subject is the geometrical design and control of a fully actuated drone, intended to be used as a flying operating-platform for a manipulator. Starting with the general geometrical description of a symmetric drone with six rotors, methods for the application specific design of a fully actuated drone are developed. Furthermore general influencing principles of geometric parameters on the forces and torques that can be generated by the drone, are pointed out. To characterize the drone's wrench-space, it is reduced to so called support vectors, which are given by the hovering thrust, the minimum guaranteed force in a horizontal direction and the minimum guaranteed torque in any direction. Additionally, analytic formulas are derived for the mentioned support vectors. Based on the description by the support vectors, a formulation of metrics is introduced, to enable the assessment of a specific drone geometry by a single scalar measure, to determine the ideal drone geometry for a specific application. Targeting the issue of controlling the flight system, consisting of the drone and the manipulator, a concept is developed that realizes a virtual dissplacement of the center of mass by decoupling the equations of motion and therby facilitates a precise control, independent of the actual location of the system's center of mass. Drohne UAV Modellierung Entwurf Regelung Kraftraum Schwerpunkt Manipulation aus der Luft vollaktuiert verkippte Rotoren Drone UAV Modeling Design Control Wrench Space Center of Mass aerial manipulation fully actuated tilted rotors ddc:600 ddc:620 rvk:ZO 7440 Robotik Mobile Robotik Drohne UAV Manipulator Nichtlineare Regelung Modellierung Entwurf Schwerpunkt
33	Entwicklung und Modellierung einer vollaktuierten Drohne Schuster, Micha 26 April 2018 (has links) Diese Diplomarbeit beschäftigt sich mit der geometrischen Auslegung und Regelung einer vollaktuierten Drohne, die als fliegende Arbeitsplattform für einen Manipulator dienen soll. Dabei werden ausgehend von der geometrischen Beschreibung einer allgemeinen, symmetrischen Drohne mit sechs Rotoren Methoden entwickelt, die den anforderungsbezogenen Entwurf der Geometrie einer vollaktuierten Drohne ermöglichen. Darüber hinaus werden prinzipielle Einflussmechanismen einzelner Geometrieparameter auf die durch die Drohne erzeugbaren Kräfte und Momente aufgezeigt. Zur Charakterisierung des Raums aller erzeugbaren Lasten wird dieser auf sogenannte Stützvektoren reduziert. Als Stützvektoren dienen dabei die für den Schwebeflug nötige Schubkraft, die garantierte Mindestkraft in horizontaler Richtung und das garantierte Mindestmoment um eine beliebige Achse, zu deren Berechnung zusätzlich analytische Formeln hergeleitet werden. Aufbauend auf die Beschreibung durch Stützvektoren wird die Formuliernung von Metriken vorgestellt, die die Bewertung einer Drohnengeometrie durch eine einzige skalare Maßzahl ermöglichen, wodurch die je nach Anwendung optimale Drohnengeometrie ermittelt werden kann. Zur Regelung des Systems aus Drohne und Manipulator wurde ein Regelungskonzept entwickelt, welches durch eine Entkopplung der Bewegungsgleichungen eine virtuelle Verschiebung des Schwerpunkts in das Drohnenzentrum realisiert und so eine präzise Regelung unabhängig von der tatsächlichen Schwerpunktlage ermöglicht. / This thesis’ subject is the geometrical design and control of a fully actuated drone, intended to be used as a flying operating-platform for a manipulator. Starting with the general geometrical description of a symmetric drone with six rotors, methods for the application specific design of a fully actuated drone are developed. Furthermore general influencing principles of geometric parameters on the forces and torques that can be generated by the drone, are pointed out. To characterize the drone's wrench-space, it is reduced to so called support vectors, which are given by the hovering thrust, the minimum guaranteed force in a horizontal direction and the minimum guaranteed torque in any direction. Additionally, analytic formulas are derived for the mentioned support vectors. Based on the description by the support vectors, a formulation of metrics is introduced, to enable the assessment of a specific drone geometry by a single scalar measure, to determine the ideal drone geometry for a specific application. Targeting the issue of controlling the flight system, consisting of the drone and the manipulator, a concept is developed that realizes a virtual dissplacement of the center of mass by decoupling the equations of motion and therby facilitates a precise control, independent of the actual location of the system's center of mass. info:eu-repo/classification/ddc/600 ddc:600 info:eu-repo/classification/ddc/620 ddc:620
34	Analysis of a novel thermoelectric generator in the built environment Lozano, Adolfo 05 October 2011 (has links) This study centered on a novel thermoelectric generator (TEG) integrated into the built environment. Designed by Watts Thermoelectric LLC, the TEG is essentially a novel assembly of thermoelectric modules whose required temperature differential is supplied by hot and cold streams of water flowing through the TEG. Per its recommended operating conditions, the TEG nominally generates 83 Watts of electrical power. In its default configuration in the built environment, solar-thermal energy serves as the TEG’s hot stream source and geothermal energy serves as its cold stream source. Two systems-level, thermodynamic analyses were performed, which were based on the TEG’s upcoming characterization testing, scheduled to occur later in 2011 in Detroit, Michigan. The first analysis considered the TEG coupled with a solar collector system. A numerical model of the coupled system was constructed in order to estimate the system’s annual energetic performance. It was determined numerically that over the course of a sample year, the solar collector system could deliver 39.73 megawatt-hours (MWh) of thermal energy to the TEG. The TEG converted that thermal energy into a net of 266.5 kilowatt-hours of electricity in that year. The second analysis focused on the TEG itself during operation with the purpose of providing a preliminary thermodynamic characterization of the TEG. Using experimental data, this analysis found the TEG’s operating efficiency to be 1.72%. Next, the annual emissions that would be avoided by implementing the zero-emission TEG were considered. The emission factor of Michigan’s electric grid, RFCM, was calculated to be 0.830 tons of carbon dioxide-equivalent (CO2e) per MWh, and with the TEG’s annual energy output, it was concluded that 0.221 tons CO2e would be avoided each year with the TEG. It is important to note that the TEG can be linearly scaled up by including additional modules. Thus, these benefits can be multiplied through the incorporation of more TEG units. Finally, the levelized cost of electricity (LCOE) of the TEG integrated into the built environment with the solar-thermal hot source and passive ground-based cold source was considered. The LCOE of the system was estimated to be approximately $8,404/MWh, which is substantially greater than current generation technologies. Note that this calculation was based on one particular configuration with a particular and narrow set of assumptions, and is not intended to be a general conclusion about TEG systems overall. It was concluded that while solar-thermal energy systems can sustain the TEG, they are capital-intensive and therefore not economically suitable for the TEG given the assumptions of this analysis. In the end, because of the large costs associated with the solar-thermal system, waste heat recovery is proposed as a potentially more cost-effective provider of the TEG’s hot stream source. / text Thermoelectric generator TEG Novel thermoelectric generator Thermoelectrics Thermoelectric effect Thermoelectric modules Thermoelectric device Patent application Hot stream source Cold stream source EIA EERE Systems-level analysis Energy balance Control volume analysis Thermodynamic analysis Insolation data Insolation incident on a panel Incident insolation Extraterrestrial insolation NREL Ambient temperature data NOAA Renewable energy sources Energy generation technology Electricity generation technology Thermal energy Coupled system Emissions Greenhouse gas GHG Emissions analysis Zero-emission Emissions avoided Emission factor EF Reliability First Corporation RFC Built environment Integrated into the built environment Solar-thermal energy Solar collector system Photovoltaic thermal PVT panel Thermal storage tank Geothermal energy Geothermal heat pump GHP Ground source heat pump GSHP Numerical analysis Numerical model MATLAB Finite-difference Euler explicit Electric grid Annual energetic performance Annual electricity generation Operating efficiency System efficiency Thermodynamic characterization Economic analysis Levelized cost of energy LCOE Waste heat recovery Carbon dioxide equivalent CO2e Capital costs Installed costs Operating and maintenance costs

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