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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

INSTRUMENTED BALLISTIC TEST PROJECTILE

Flyash, Boris, Platovskiy, Steve, Cantatore, Dominick 10 1900 (has links)
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / For years, ballisticians have been studying the phenomena associated with cannon launched projectiles. In particular, is the study of the pressure internal to the cannon and about the base of the projectile during cannon launch through muzzle exit. Pressure on the base is thought to be uniform and therefore hydrostatic, even though there are undulations in the magnitude of the pressure from the burning propellant. This paper studies various phenomena of the launching of 155-mm artillery projectiles with slip band obturators. Specifically, pressure gradients in and around the base and pressure along the body caused by obturator “blow-by” during the interior ballistic flight and muzzle exit. This study is accomplished by use of two different types of Instrumented Ballistic Test Projectiles (IBTP). The objective of tests performed was to successfully capture pressure and acceleration live data which will be used to characterize the localized base and body pressurization on a 155-mm artillery cannon launched projectile. The telemetry system used for these tests was the ARRT-124 telemetry system provided by the Armament Research, Development, and Engineering Center, specifically the Precision Munitions Instrumentation Division. The telemetry system used for the IBTP employs a traditional FM/FM technique for monitoring and transmitting a number of analog channels. Preliminary captured data indicated localized fluctuations in pressure that are not uniform over the base and the projectile body. Further studying of the data may provide insight into other projectile dynamics such as fin deployment, set forward accelerations at muzzle exit, and obturator performance.
2

Lufttrycksförgrening i digital tryckmätare för rökdykare : Konstruktion från problem till prototyp / Air Manifold inside a Digitalised Pressure Gauge for Firefighters : Construction from problem to prototype

Molly, Sandbacka, Jenny, Larsson January 2017 (has links)
This report is a Bachelor thesis executed at Jönköping University during the spring of 2017 by Jenny Larsson and Molly Sandbacka. The thesis was conducted as a final part of the education program for the Degree of Bachelor of Science in Mechanical Engineering, specialisation Product Design and Development. The most dangerous and physically demanding work assignment allowed in Sweden is to work as a firefighter. The firefighters carries oxygen cylinders on their backs and from there the oxygen is transported to a breathing mask and to a pressure gauge. The pressure gauge indicates how much oxygen is left and gives the firefighters an idea over ​​how long they can work. More features could be applied on the device if it were to be digitalised. A digitalisation laid the foundation of the Bachelor thesis performed on behalf of the technical consulting company Combitech in Jönköping. The aim with this project was, from problem to prototype, to construct a component within a pressure gauge. The component shall distribute the oxygen from the cylinders to partly an analogue gauge and partly a digital pressure sensor. Another section of the project was to choose material and suggest how the device should remain tight. Based on theories of the product development process different methods has been used to deliver two concept proposals with different advantages regarding function, manufacturing and cost. One concept has a freely rotating system that promotes the function, while the other concept is easier to manufacture and thus a cheaper alternative. The project has also resulted in three recommended metals: low alloy steel, medium carbon steel and brass quality already used on one of the components of the pressure gauge. The concepts and materials are presented and analysed by simulations, prototypes, risk analysis and value analysis. The results of the Bachelor thesis have contributed with a component so the equipment of the firefighter can be modernised through a lighter, more flexible and digitalised pressure gauge. Furthermore, the other components of the pressure gauge and the full device need to be tested to check that the specifications are met. / Denna rapport behandlar det examensarbete som utförts vid Jönköping University under vårterminen 2017 av Jenny Larsson och Molly Sandbacka. Examensarbetet genomfördes som en avslutande del av utbildningen till högskoleingenjör och teknologie kandidat inom Maskinteknik produktutveckling och design. Att arbeta som rökdykare är en av de allra farligaste och fysiskt mest krävande arbetsuppgifter som tillåts i Sverige. På ryggen bär rökdykare en eller två syrgastuber och därifrån transporteras syret till en andningsmask och till en tryckmätare. Denna mätare indikerar hur mycket syrgas som finns kvar och ger då rökdykaren en uppfattning över hur länge rökdykaren kan arbeta. Digitalisering av denna mätare skulle medföra att fler funktioner skulle kunna appliceras. Detta lade grunden för examensarbetet som genomfördes på uppdrag av teknikkonstultbolaget Combitech i Jönköping. Syftet var att konstruera, från problem till prototyp, en komponent som ska förgrena syrgas till dels en analog manometer, dels en digital trycksensor inuti en tryckmätare. Examensarbetet skulle även innefatta materialval och förslag kring hur mätaren ska förbli tät. Genom metoder utifrån teorier om produktutvecklingsprocessen har arbetet resulterat i två konceptförslag med olika fördelar gällande funktion, tillverkning och kostnad. Det ena konceptet har en inbyggd svivelfunktion vilken främjar funktionen, medan det andra konceptet är enklare att tillverka och därmed ett billigare alternativ. Arbetet har även resulterat i tre på lufttrycksförgreningen applicerbara metaller: låglegerat stål, medium kolstål och en mässingskvalité som redan används på en av delkomponenterna i tryckmätaren. De båda koncepten samt materialen presenteras och analyseras genom simuleringar, prototyper, riskanalys och värdeanalys. Examensarbetets resultat har bidragit med en komponent så att rökdykarens utrustning kan moderniseras genom en smidigare, lättare och digitaliserad tryckmätare. Vidare behöver tryckmätarens övriga komponenter och den fulla enheten testas för att kontrollera så att kravspecifikationen uppfylls.
3

Microcapteurs de pression à base de manganites épitaxiées / Micro-pressure sensors based on epitaxial functional oxides

Le Bourdais, David 16 February 2015 (has links)
Les oxydes sont des matériaux complexes possédant une physique riche et toujours au centre de nombreuses recherches. Parmi ces oxydes, les manganites ont retenu notre attention car ils présentent une transition métal-isolant abrupte en température, générant un très fort coefficient en température en conditions d’environnement standards. L’objectif de ce travail est de démontrer que ce fort coefficient peut être exploité pour l’amélioration des performances des jauges de pression de type Pirani qui subissent un certain essoufflement dans leur développement. La voie menant à l’aboutissement d’une telle jauge à base d’oxydes pose en revanche un certain nombre de limites technologiques à lever et auxquelles nous avons répondu. La première de ces limites concerne l’intégration des oxydes monocristallins sur silicium, que nous avons reproduite et étendue au cas des substrats de type SOI et GaAs. Nos procédés proposent de passer par deux techniques, l’épitaxie par jets moléculaire et l’ablation laser, pour assurer une croissance optimale de nos films sur ces substrats et d’assurer la reproductibilité de leur réponse en température, notamment la position de leur température de transition en accord avec l’état de l’art. L’épitaxie de ces oxydes génère un niveau de contrainte non négligeable qui n’a jamais été mesuré. En concevant divers dispositifs autosupportés, et en s’appuyant sur les considérations théoriques et des modélisations par éléments finis, nous avons pu quantifier la relaxation de cette contrainte importante et assurer près de 100% de reproductibilité des systèmes suspendus. Ces mêmes systèmes nous permettent de caractériser pour la première fois le facteur de jauge des manganites monocristallines par l’application d’une contrainte contrôlée par nanoindentation. Il est également démontré qu’ils constituent des jauges de pression Pirani à la sensibilité accrue de deux ordres de grandeur pour une consommation en puissance réduite. Des solutions permettant d’améliorer l’ensemble des aspects de ces jauges sont étudiées. / Functional perovskite oxides are of great interest for fundamental and applied research thanks to the numerous physical properties and inherent mechanisms they display. With the maturation of thin film deposition techniques, research teams are able to reproduce oxide films and nanostructures of great crystalline quality with some of the most remarkable properties found in physics, a state leading now to upper-level thoughts like their ability to fulfill industrial needs. This thesis work is an answer to some of the problematics that arise when considering the oxide transition from the research to the industrial world, by focusing on their integration for micromechanical devices (MEMS) such as sensors. In order to ease the access to MEMS manufacturing, it is of importance to allow the deposition of thin oxide films on semiconductor substrates. A first study show that these access bridges can be crossed when using appropriate buffer layers such as SrTiO3 deposited on Silicon or gallium arsenide – produced in close collaboration with INL by Molecular Beam Epitaxy - and yttria-stabilized zirconia directly grown on silicon by pulsed laser deposition, which adapts the surface properties of the substrate to perovksite-based materials. Formation of thin epitaxial and monocristalline films of functional oxides is thus allowed on such buffer layers. As an example, characterization of two mixed-valence manganites La0.80Ba0.20MnO3 and La0.67Sr0.33MnO3 demonstrates that both materials are of excellent crystalline quality on these semiconducting substrates and that their physical characteristics match the one found on classical oxide substrates like SrTiO3. Stress evolution in thin films, which has a major effect in epitaxial materials, is then addressed to quantify its impact on oxide microstructure viability. This work gives an identification of the most significant factors favoring stress generation in the case of the films we produced. Then, based on the deformation measurement of free-standing cantilevers made of manganites on pseudo-substrates, and with the support of appropriate analytical models, a new state of equilibrium is established, giving new information about the evolution of static stress from deposition to MEMS device manufacturing. Solutions to manage their reproducibility is then studied. From another perspective, free-standing microstructures made of monocristaline manganites were used to display the effect of dynamical strain on their electrical resistivity (piezoresistivity) and their inherent structures.Finally, a specific example of the capabilities of reproducible free-standing microbridges made of manganites is presented through the conception of a pressure gauge based on Pirani effect. Indeed, it is shown that the abrupt resistivity change this material exhibits near their metal-to-insulating transition creates high temperature coefficients in standard application environments that can be taken as an advantage to improve the sensibility and power consumption of such gauges whose development had significantly slowed down over the past years. A set of improvements on their sensitivity range and their signal acquisition is also presented. Combined to a specific and innovative package, it is also demonstrated that Pirani gauge capabilities can be enhanced and that the complete devices fulfill embedded application requirements.
4

Temporal Variations in the Compliance of Gas Hydrate Formations

Roach, Lisa Aretha Nyala 20 March 2014 (has links)
Seafloor compliance is a non-intrusive geophysical method sensitive to the shear modulus of the sediments below the seafloor. A compliance analysis requires the computation of the frequency dependent transfer function between the vertical stress, produced at the seafloor by the ultra low frequency passive source-infra-gravity waves, and the resulting displacement, related to velocity through the frequency. The displacement of the ocean floor is dependent on the elastic structure of the sediments and the compliance function is tuned to different depths, i.e., a change in the elastic parameters at a given depth is sensed by the compliance function at a particular frequency. In a gas hydrate system, the magnitude of the stiffness is a measure of the quantity of gas hydrates present. Gas hydrates contain immense stores of greenhouse gases making them relevant to climate change science, and represent an important potential alternative source of energy. Bullseye Vent is a gas hydrate system located in an area that has been intensively studied for over 2 decades and research results suggest that this system is evolving over time. A partnership with NEPTUNE Canada allowed for the investigation of this possible evolution. This thesis describes a compliance experiment configured for NEPTUNE Canada’s seafloor observatory and its failure. It also describes the use of 203 days of simultaneously logged pressure and velocity time-series data, measured by a Scripps differential pressure gauge, and a Güralp CMG-1T broadband seismometer on NEPTUNE Canada’s seismic station, respectively, to evaluate variations in sediment stiffness near Bullseye. The evaluation resulted in a (- 4.49 x10-3± 3.52 x 10-3) % change of the transfer function of 3rd October, 2010 and represents a 2.88% decrease in the stiffness of the sediments over the period. This thesis also outlines a new algorithm for calculating the static compliance of isotropic layered sediments.
5

Temporal Variations in the Compliance of Gas Hydrate Formations

Roach, Lisa Aretha Nyala 20 March 2014 (has links)
Seafloor compliance is a non-intrusive geophysical method sensitive to the shear modulus of the sediments below the seafloor. A compliance analysis requires the computation of the frequency dependent transfer function between the vertical stress, produced at the seafloor by the ultra low frequency passive source-infra-gravity waves, and the resulting displacement, related to velocity through the frequency. The displacement of the ocean floor is dependent on the elastic structure of the sediments and the compliance function is tuned to different depths, i.e., a change in the elastic parameters at a given depth is sensed by the compliance function at a particular frequency. In a gas hydrate system, the magnitude of the stiffness is a measure of the quantity of gas hydrates present. Gas hydrates contain immense stores of greenhouse gases making them relevant to climate change science, and represent an important potential alternative source of energy. Bullseye Vent is a gas hydrate system located in an area that has been intensively studied for over 2 decades and research results suggest that this system is evolving over time. A partnership with NEPTUNE Canada allowed for the investigation of this possible evolution. This thesis describes a compliance experiment configured for NEPTUNE Canada’s seafloor observatory and its failure. It also describes the use of 203 days of simultaneously logged pressure and velocity time-series data, measured by a Scripps differential pressure gauge, and a Güralp CMG-1T broadband seismometer on NEPTUNE Canada’s seismic station, respectively, to evaluate variations in sediment stiffness near Bullseye. The evaluation resulted in a (- 4.49 x10-3± 3.52 x 10-3) % change of the transfer function of 3rd October, 2010 and represents a 2.88% decrease in the stiffness of the sediments over the period. This thesis also outlines a new algorithm for calculating the static compliance of isotropic layered sediments.

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