Dissertations / Theses on the topic 'Shock'
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Schwendeman, Donald William Whitham G. B. "Numerical shock propagation using geometrical shock dynamics /." Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-03082008-083041.
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Zhou, Chunyan. "Shock response and shock protection of portable electronics /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?MECH%202007%20ZHOU.
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Morrow, Heather. "Shock absorption." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0016/MQ54662.pdf.
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Long, Jessica B. "Paradoxical effects of shock the role of shock intensity and interresponse times followed by shock /." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10369.
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Thesis (Ph. D.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains viii, 95 p. : ill. Includes abstract. Includes bibliographical references (p. 40-43).
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Hennessey, Noel. "Overcoming Shock: An Examination of Transfer Shock and Student Resiliency." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/560635.
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This project examines the systemic causes of transfer shock, the phenomenon wherein students transitioning onto a university campus from a community college experience a drop in their grade point average (GPA) in their first semester of transfer. Previous research has focused on student characteristics that are predictive of transfer shock, but few researchers have approached this topic from the perspective of the students themselves. This study seeks to understand how transfer students experience the initial transition onto the four-year university campus and the interactions with managerial professionals, and how those interactions impact the likelihood of students experiencing transfer shock or not. I used the work of Tinto (1975) and Deil-Amen (2011), as well as interviews with 15 transfer students, to theorize that students' procedural interactions are significant for their socio-academic integration. This study demonstrates the process of socio-academic integration and highlights the ways that the institution can support or impede student academic performance and success.
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Todd, Susan Katharine. "Shock assisted ventilation." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843314/.
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Respiratory distress syndrome is the major cause of mortality in premature babies. Increasing numbers of neonates are now surviving the disease due to advances in techniques used in neonatal intensive care units. Mechanical ventilation is an essential part of the treatment for respiratory distress syndrome and is an area in which improvements and modifications are constantly being made. In the early 1980's a new infant ventilator was introduced involving ventilation by a distal jet. As yet, the mechanisms by which the distal jet ventilator enhances gas exchange are unknown. Original experiments are carried out to record the attenuation and speeds of the pressure wave produced by the distal jet ventilator. The observed changes in wave shape and the high wave speed imply that the ventilator produces waves operating within an acoustic regime. An understanding of the gas exchange mechanisms active in shock assisted ventilation is initiated by a comprehensive investigation of the transport properties of acoustic waves. The advection and diffusion that result from a linear concentration gradient in an acoustic flow are analysed, from the Eulerian and Lagrangian viewpoints. The Eulerian investigation shows that the total flux of tracer through a given pipe can be optimized by choosing the frequency appropriately. The Lagrangian transport is increased as both frequency and radius increase. For all values of parameters, Lagrangian streaming is observed, with a steady net flow in the pipe core away from the tube entrance and an opposing net flow near the tube walls.
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Mirshekari, Gholamreza. "Microscale shock tube." Thèse, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1897.
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Abstract : This project aims at the simulation, design, fabrication and testing of a microscale shock tube. A step by step procedure has been followed to develop the different components of the microscale shock tube and then combine them together to realize the final device. The document reports on the numerical simulation of flows in a microscale shock tube, the experimental study of gas flow in microchannels, the design, microfabrication, and the test of a microscale shock tube. In the first step, a one-dimensional numerical model for simulation of transport effects at small-scale, appeared in low Reynolds number shock tubes is developed. The conservation equations have been integrated in the lateral directions and threedimensional effects have been introduced as carefully controlled sources of mass, momentum and energy, into the one-dimensional model. The unsteady flow of gas behind the shock wave is reduced to a quasi-steady laminar flow solution, similar to the Blasius solution. The resulting one-dimensional equations are solved numerically and the simulations are performed for previously reported low Reynolds number shock tube experiments. Good agreement between the shock structure simulation and the attenuation due to the boundary layers has been observed. The simulation for predicting the performance of a microscale shock tube shows the large attenuation of shock wave at low pressure ratios. In the next step the steady flow inside microchannels has been experimentally studied. A set of microchannels with different geometries were fabricated. These microchannels have been used to measure the pressure drop as a function of flow rate in a steady compressible flow. The results of the experiments confirm that the flow inside the microscale shock tube follows the laminar model over the experiment's range of Knudsen number. The microscale shock tube is fabricated by deposition and patterning of different thin layers of selected materials on the silicon substrate. The direct sensing piezoelectric sensors were fabricated and integrated with microchannels patterned on the substrate. The channels were then covered with another substrate. This shock tube is 2000 µm long and it has a 2000 µm wide and 17 µm high rectangular cross section equipped with 5 piezoelectric sensors along the tube. The packaged microscale shock tube was installed in an ordinary shock tube and shock waves with different Mach numbers were directed into the channel. A one-dimensional inviscid calculation as well as viscous simulation using the one-dimensional model have also been performed for the above mentioned geometry. The comparison of results with those of the same geometry for an inviscid flow shows the considerable attenuation of shock strength and deceleration of the shock wave for both incident and reflected shock waves in the channel. The comparison of results with numerically generated results with the one-dimensional model presents good agreement for incident shock waves. // Résumé : Ce projet vise à la simulation, la conception, la fabrication et l'essai d'un tube à choc a l'échelle micrométrique. Une procédure étape par étape a été suivie pour développer les différentes composantes du tube à choc à l'échelle micrométrique, puis les assembler pour la réalisation finale du dispositif. Le document rend compte de la simulation numérique, de l'étude expérimentale de l'écoulement du gaz dans les microcanaux, de la conception, de la microfabrication, et de l'essai d'un tube à choc à l'échelle micrométrique. Dans la première étape, un modèle numérique unidimensionnel pour la simulation des effets de transport à des petites échelles dans des tubes à choc à faible nombre de Reynolds, est développé. Les équations de conservation ont été intégrés latéralement et les effets tridimensionnels ont été mis en place avec des sources bien contrôlées de masse, du moment et de l'énergie, dans un modelé à une dimension. L'écoulement non stable du gaz après le choc est réduit à un flux laminaire quasi permanent, solution similaire à la solution de Blasius. Les équations unidimensionnelles résultantes sont résolues numériquement et des simulations sont effectuées pour des expériences précédemment rapportées de tube à choc en faible nombre de Reynolds. II y a une bonne correspondance entre la structure du choc et la simulation. L'atténuation due à la couche limite a été observée. La simulation pour prédire les performances d'un tube à choc à l'échelle micrométrique a montré la grande atténuation de l'onde de choc à faible taux de pression. Dans l'étape suivante, le flux constant à l'intérieur des microcanaux a été étudié expérimentalement. Quelques microcanaux avec différentes géométries ont été fabriqués. Ces microcanaux ont été utilises pour mesurer la chute de pression en fonction du débit dans un écoulement compressible flux stable. Les résultats de l'expérience confirment que l'écoulement à l'intérieur du tube à choc à l'échelle micrométrique suit le modèle laminaire sur un large éventail de nombre de Knudsen. Le tube à choc à l'échelle micrométrique est fabrique par les dépôts et gravure des différentes couches minces de certains matériaux sur un substrat de silicium. Des capteurs piézoélectriques à détection directe sont fabriques et intégrés avec les microcanaux caïques sur le substrat. Les canaux sont ensuite recouverts d'un autre substrat. Le tube à choc est long de 2000 µm et a une section rectangulaire de 2000 µm de large et 17 µm de haut et es téquipé avec 5 capteurs piézoélectriques dans le tube. Le tube à choc à l'échelle micrométrique est installé dans un tube à choc standard afin d'entre exposés à une onde de choc avec différents nombres de Mach. Un calcul unidimensionnel inviscide ainsi que la simulation visqueuse avec le modèle unidimensionnel a aussi été effectué pour cette géometrie. La comparaison des résultats avec ceux obtenus avec la même géométrie avec avec un flux Inviscid montre une large atténuation de la force de choc et une décélération de l'onde de choc pour les deux ondes de choc incidentes et réfléchies dans le canal. La comparaison de résultats avec les résultats générés numériquement par modèle unidimensionnel pressent un bon accord pour onde de choc de l'incident.
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Sen, Srimoyee, and Naoki Yamamoto. "Chiral Shock Waves." AMER PHYSICAL SOC, 2017. http://hdl.handle.net/10150/624056.
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We study the shock waves in relativistic chiral matter. We argue that the conventional Rankine-Hugoinot relations are modified due to the presence of chiral transport phenomena. We show that the entropy discontinuity in a weak shock wave is quadratic in the pressure discontinuity when the effect of chiral transport becomes sufficiently large. We also show that rarefaction shock waves, which do not exist in usual nonchiral fluids, can appear in chiral matter. The direction of shock wave propagation is found to be completely determined by the direction of the vorticity and the chirality of fermions. These features are exemplified by shock propagation in dense neutrino matter in the hydrodynamic regime.
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Mutz, Andrew Howard Vreeland Thad. "Heterogeneous shock energy deposition in shock wave consolidation of metal powders /." Diss., Pasadena, Calif. : California Institute of Technology, 1991. http://resolver.caltech.edu/CaltechETD:etd-06282007-091349.
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Lloyd, Alan. "Performance of reinforced concrete columns under shock tube induced shock wave loading." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28510.
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Recent events including deliberate attacks and accidental explosions have highlighted the need for greater research in structural response to blast loading. One of the primary research focuses has been on the prevention of progressive collapse of structures. The response of vertical load transferring members, such as columns, is of particular importance to progressive collapse prevention. In order to understand and predict the behaviour of the global structure during and after a blast loading event, a greater understanding of column behaviour must be developed. Currently there is a limited amount of experimental test data available on the response of reinforced concrete columns exposed to blast loads. This thesis presents the results of experimental research involving tests of scaled reinforced concrete columns exposed to shock wave induced impulsive loads using the University of Ottawa Shock Tube.
A total of 14 half scale reinforced concrete columns were constructed and tested under blast pressures. The columns were designed according to Canadian Standard Association (CSA) Standard A23.3 for the "Design of Concrete Structures" (2006) standard as first story columns for both seismic and non-seismic regions. Axial load was applied to levels similar to what can be expected in actual structures. The columns were exposed to various pressure-impulse combinations which resulted in a range of column response. Comparisons are made between seismically designed and detailed columns and those that represent non-seismic gravity load columns in terms of displacement under similar shockwave loading.
In addition, numerical analyses were conducted using single degree of freedom dynamic analysis. The numerical analysis accounts for the loss of axial load observed with horizontal displacement, strain rate effects on material strengths, the formation of plastic hinges in the column near the supports and at mid-height and the corresponding change in resistance and the response mode shape. The numerical analysis is validated with the experimental results and proven to accurately predict displacement of reinforced concrete columns under shock wave loading. The results indicate that an equivalent single degree of freedom model may be used to determine the response of a column under air blast induced shock loading if proper displacement-resistance models that account for material strength increase factors and change in axial load are used.
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Jamaluddin, Ahmad Riza. "Free-Lagrange simulations of shock-bubble interaction in extracorporeal shock wave lithotripsy." Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/47507/.
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Molder, Sannu. "Curved aerodynamic shock waves." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110629.
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1AbstractCurved shock theory (CST) has been extended to apply to axisymmetric shocks in non-uniform flow. A general formula has been derived for the vorticity jump across a doubly curved shock in non-uniform flow. Influence coefficient forms of equations for the gradients and vorticity show the effect of changing pre-shock conditions. CST has been applied to a series of simple shock flows and to the orientation of the sonic surface at the rear face of a doubly curved shock. This orientation is significant in determining the occurrence of embedded shocks in the post-shock flow. Application of CST to curved, concave, normal shocks allowed the derivation of an explicit relationship between the shock's curvature and the length of down-shock subsonic flow. Investigations of conical flows by analysis, CFD and experiment all failed to demonstrate the existence of regular reflection of shocks at the centre line of axisymmetric flows. An analytically predicted conical shock, on the calculated streamline, does not extend all the way to the centre line but terminates in Mach reflection. It appears that the existence of an analytical Taylor-Mccoll (T-M) solution is not in itself a guarantee of the physical existence of a conical flow in all cases. The T-M equations predict the existence of an axisymmetric centered compression fan, analogous to the Prandtl-Meyer fan in planar flow. A free-standing conical shock is located downstream of the compression fan. Both features have been shown to exist by CFD as well as experiment. Busemann flow is the only flow where these wave structures can exist; it is possible to reflect an incident, centered compression as a conical shock. Discovery of an inflection point on the Busemann streamline has an important implication to spontaneous starting of Busemann intakes. Three types of flow can exist behind a doubly curved concave shock; characterized by the orientation of the sonic surface which, in turn, is determined by the pre-shock Mach number and the shock curvatures ratio. Shapes of special axial shock surfaces, with straight post shock streamlines (Crocco shocks), or vanishing streamwise pressure gradient (Thomas shocks) and shocks with specific sound reflectivity (zero, if desired), have been calculated and illustrated. Boundary layer generated noise abatement is a possibility. Local flow choking, near the leading edge, leads to shock detachment from a curved wedge with such detachment depending on freestream Mach number, the wedge2angle, the wedge curvature and the wedge length. These are new criteria for shock detachment with analogies extending to the transition from regular to Mach reflection of shock waves.1RésuméLa théorie des ondes de chocs courbées (TOCC; Curved Shock Theory) a été généralisée aux chocs axisymétriques dans un écoulement non uniforme. Une formule générale a été dérivée pour les sauts de vorticité à travers un choc à double courbe dans un écoulement non uniforme. La forme coefficient d'influence des équations des gradients et de la vorticité démontrent l'effet de la variation des conditions en amont. La TOCC a été appliquée à plusieurs écoulements simples avec chocs incluant l'orientation de la surface sonique à la face arrière d'un choc à double courbe. Cette orientation est importante pour déterminer l'existence d'ondes de choc intégrées à l'écoulement aval. L'application de la TOCC aux ondes de choc courbées, concaves et normales permet de dériver une relation explicite entre la courbe du choc et la longueur de l'écoulement subsonique derrière l'onde. L'étude analytique, numérique et expérimentale des écoulements coniques n'a pas permis de démontrer l'existence de réflexions régulières des chocs à l'axe de symétrie des écoulements. Un choc conique prédit analytiquement sur la ligne d'écoulement n'atteint pas l'axe central, mais se termine en réflexion Mach. Il semble que l'existence d'une solution Taylor-Mccoll (T-M) ne garantit pas l'existence physique d'un écoulement conique. Les équations T-M prédisent l'existence d'un train d'ondes de compression axisymétrique, analogue au train d'ondes de Prandtl-Meyer dans un écoulement planaire. Un choc conique détaché est situé en aval du train de compression. L'existence des deux caractéristiques a été démontrée par CFD ainsi qu'expérimentalement. L'écoulement Busemann est le seul écoulement où ces structures d'ondes peuvent exister : une compression centrée peut être reflétée en onde de choc conique. La découverte d'un point d'inflexion dans la ligne d'écoulement de Busemann a une implication importante au démarrage spontané de diffuseurs Busemann. Trois types d'écoulements peuvent exister à l'arrière d'un choc concave à double courbure : ils sont caractérisés par l'orientation de la surface sonique qui, à son tour, est déterminée par le nombre de Mach pré-choc et le ratio de courbures du choc. Des formes de surfaces d'ondes de choc axiales particulières, avec écoulement droit en aval (chocs Crocco), ou avec un gradient de pression tendant vers zéro dans l'axe d'écoulement (chocs Thomas) ainsi que des chocs avec une réflectivité acoustique spécifique (incluant nulle) ont été calculées et illustrées. Une réduction du bruit de couche limite est aussi possible.2L'étranglement local au bord d'attaque d'une pointe courbée mène au détachement de l'onde de choc, lequel dépend du nombre de Mach de l'écoulement libre, de l'angle, de la courbure et de la longueur de la pointe. Ce sont de nouveaux critères pour le détachement du choc avec des analogies pouvant s'étendre aux transitions des réflexions régulières aux réflexions Mach.
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Jinks, Edward. "Adaptive shock control bumps." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/45535.
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The evolution of Adaptive Shock Control Bumps (SCB) presented in this work is a result of an investigation into transonic flow control devices. The primary application is on transonic passenger jet aircraft during cruise and within supersonic intakes. It is in these locations that normal shocks of strength Mach 1.2-1.5 typically occur which SCB aim to manipulate and exploit. The original concept was developed by [Ashill et al., 1992] featured a flexible plate with actuators beneath the surface. The complex fluid-structure interaction (FSI) between the shock and plate has been a focus of this work with panel flutter studies heavily supplementing traditional SCB design methods. Adaptive SCB represent a required approach in order to negate poor off-design performance of static SCB. A coupled 2D aero-structural solver was developed using OpenFOAM [2017] and ABAQUS [2007] which provides a tool to evaluate the effects of varying plate proper- ties. Cavity pressure, plate length, thickness and material stiffness were found to be influential in the overall performance with four test cases developed. With lengths, lb = 150 − 200 mm and thicknesses t = 0.4 − 0.6 mm using Al-7075-T6, experimental models were produced and tested in a Mach 1.4 blowdown supersonic wind tunnel. These were sized using the coupled solver to deform passively and trigger the bifurca- tion of the shock. This new type of device showed potential for a passive adaptive SCB however all suffered from varying amounts of reacceleration over the rear surface. An aero-structural optimisation procedure is performed to position displacement con- straints beneath the flexible plate to control surface curvature. This was the driving force behind the detrimental reacceleration. The optimiser used a new performance metric which focussed upon smearing the adverse pressure gradient across the SCB which reduced the likelihood of plastic deformation. Optimal SCB have been shown to deploy and retract beneath an unsteady shock and successfully bifurcated the shock on demand.
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Qian, Cheng. "Simulation of Mechanical Shock with Finite Element Analysis and Estimation of Shock Attenuation." Thesis, KTH, Hållfasthetslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-294549.
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Space equipment is often subjected to mechanical shocks. Some devices like electronics are sensitive to shocks, and they can easily be damaged. To protect these devices, it is important to study shock penetrations in space structures. The Finite Element Method is an effective tool to simulate response to transient excitations. Unlike Statistical Energy Analysis (SEA) which can ensure sufficient accuracy in high frequency range, Finite Element Analysis (FEA) is limited to low frequency range, but has no spatial restrictions. In this thesis, Tuma’s digital filter method and Irvine’s recursive digital method were combined to calculate the Shock Response Spectrum (SRS). FEA models based on a given experimental system, i.e., shock table were used to predict the structural response to Haversine shaped forces. The modal transient structural analysis in ANSYS Workbench was used as the solver. Transient analysis based on modal results neglects material and structural non-linearities, so it uses less memory and computation time. FEA and the Bernoulli beam equation were employed to simulate the shock response of cantilever beams and fixed-pinned beams to validate the FEA models. SRS calculated from FEA results were compared with those from the beam equation results. Almost no difference between Bernoulli beam equation results and FEA results for thin beams reveals that the FEA models were validated. The SRS of two beam models calculated from FEA using solid elements were compared with those using beam elements. The results from two different element types are almost consistent with each other. Response at different positions on the shock table were measured to predict the shock attenuation. The attenuation was described in the way of remaining percentage from shock source, and the curve from FEA simulation roughly agreed with the attenuation rule from the ESTEC database.Rymdutrustning utsätts ofta för mekaniska stötar, s.k. mekanisk chock. Vissa enheter, som elektronik, är känsliga för stötar och de kan lätt skadas. För att skydda dessa enheter är det viktigt att studera chockdämpningen i rymdstrukturer. Finita elementmetoden är ett effektivt verktyg för att simulera responsen vid transienta excitationer. Till skillnad från statistisk energianalys (SEA) som kan säkerställa tillräcklig noggrannhet i högfrekvensintervall, är finit elementanalys (FEA) begränsad till lågt frekvensområde, men har inga rumsliga begränsningar. I detta examensarbete kombinerades Tumas digitala filtermetod och Irvines rekursiva digitala metod för att beräkna Chockresponsspektrum (SRS). FEA-modeller baserade på ett givet experimentellt system, d.v.s. chockbord, användes för att förutsäga den strukturella responsen på Haversine-formade krafter. Den modala transienta strukturanalysen genomfördes med ANSYS Workbench. Den transienta analysen baserad på modala resultat försummar icke-linjäriteter i material och struktur för att använda mindre minne och förkorta beräkningstiden. FEA och Bernoulli-balkekvationen användes för att simulera chockresponsen av konsolbalkar och balkar med fast inspänning i ena änden och fri uppläggning i den andra änden, för att validera FEA-modellerna. SRS beräknat från FEA-resultaten jämfördes med resultat från balkekvationen. Ingen avgörande skillnad noteras mellan Bernoullis balkekvationsresultat och FEA-resultat för tunna balkar, vilket validerar FEA-modellerna. SRS för två balkmodeller beräknade från FEA med solida element jämfördes med de som använde balkelement. Resultaten från de två olika elementtyperna överensstämmer mycket bra. Responsen vid olika positioner på chockbordet mättes för att förutsäga chockdämpningen. Chockdämpningen beskrivs som kvarvarande procent av responsen vid chockkällan och kurvan från FEA-simulering överensstämde ganska bra med tumregeln för chockdämpning från ESTEC-databasen.
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Eliasson, Veronica. "On focusing of strong shock waves." Licentiate thesis, Stockholm : Department of Mechanics, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-565.
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Ziolkowski, Sandra L. "Analyzing the immediate shock deficit, a behavioural examination of post-shock activity in rats." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq21664.pdf.
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Burrell, Russell P. "Performance of Steel Fibre Reinforced Concrete Columns under Shock Tube Induced Shock Wave Loading." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23516.
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It is important to ensure that vulnerable structures (federal and provincial offices, military structures, embassies, etc) are blast resistant to safeguard life and critical infrastructure. In the wake of recent malicious attacks and accidental explosions, it is becoming increasingly important to ensure that columns in structures are properly detailed to provide the ductility and continuity necessary to prevent progressive collapse. Research has shown that steel fibre reinforced concrete (SFRC) can enhance many of the properties of concrete, including improved post-cracking tensile capacity, enhanced shear resistance, and increased ductility. The enhanced properties of SFRC make it an ideal candidate for use in the blast resistant design of structures. There is limited research on the behaviour of SFRC under high strain rates, including impact and blast loading, and some of this data is conflicting, with some researchers showing that the additional ductility normally evident in SFRC is absent or reduced at high strain loading. On the other hand, other data indicates that SFRC can improve toughness and energy-absorption capacity under extreme loading conditions. This thesis presents the results of experimental research involving tests of scaled reinforced concrete columns exposed to shock wave induced impulsive loads using the University of Ottawa Shock Tube.
A total of 13 half-scale steel fibre reinforced concrete columns, 8 with normal strength steel fibre reinforced concrete (SFRC) and 5 with an ultra high performance fibre reinforced concrete (UHPFRC), were constructed and tested under simulated blast pressures. The columns were designed according to CSA A23.3 standards for both seismic and non-seismic regions, using various fibre amounts and types. Each column was exposed to similar shock wave loads in order to provide direct comparisons between seismic and non-seismically detailed columns, amount of steel fibres, type of steel fibres, and type of concrete.
The dynamic response of the columns tested in the experimental program is predicted by generating dynamic load-deformation resistance functions for SFRC and UHPFRC columns and using single degree of freedom dynamic analysis software, RCBlast. The analytical results are compared to experimental data, and shown to accurately predict the maximum mid-span displacements of the fibre reinforced concrete columns under shock wave loading.
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Vandersall, Kevin S. "Investigation of shock-induced and shock-assisted chemical reactions in Mo-Si powder mixtures." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19146.
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Tabak, Esteban Gregorio. "Focusing of weak shock waves and the von Neumann paradox of oblique shock reflection." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/108868.
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Jones, Michelle Lynne. "Experimental Investigation of Shock-Shock Interactions over a 2-D Wedge at M = 6." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23202.
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The effects of fin-leading-edge radius and sweep angle on peak heating rates due to shock-shock interactions were investigated in the NASA Langley Research Center 20-inch Mach 6 Air Tunnel. The fin model leading edges, which represent cylindrical leading edges or struts on hypersonic vehicles, were varied from 0.25 inches to 0.75 inches in radius. A 9° wedge generated a planar oblique shock at 16.7° to the flow that intersected the fin bow shock, producing a shock-shock interaction that impinged on the fin leading edge. The fin angle of attack was varied from 0° (normal to the free-stream) to 15° and 25° swept forward. Global temperature data was obtained from the surface of the fused silica fins through phosphor thermography. Metal oil flow models with the same geometries as the fused silica models were used to visualize the streamline patterns for each angle of attack. High-speed zoom-schlieren videos were recorded to show the features and temporal unsteadiness of the shock-shock interactions. The temperature data were analyzed using one-dimensional semi-infinite as well as one- and two-dimensional finite-volume methods to determine the proper heat transfer analysis approach to minimize errors from lateral heat conduction due to the presence of strong surface temperature gradients induced by the shock interactions. The general trends in the leading-edge heat transfer behavior were similar for the three shock-shock interactions, respectively, between the test articles with varying leading-edge radius. The dimensional peak heat transfer coefficient augmentation increased with decreasing leading-edge radius. The dimensional peak heat transfer output from the two-dimensional code was about 20% higher than the value from a standard, semi-infinite one-dimensional method.Master of Science
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Fox, Thomas Edward. "Strong shock wave generation by fast electron energy deposition in shock ignition relevant plasmas." Thesis, University of York, 2014. http://etheses.whiterose.ac.uk/6625/.
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The potential role of fast electrons is one of the major unknowns in shock ignition inertial con- finement fusion. Of particular interest is the possibility that they may play a beneficial role in the generation of the ignitor shock by contributing to the ablation pressure. Here, some of the fundamental relations governing fast electron driven shock wave generation in dense plasmas are determined. To that end, a 1D planar hybrid model of fast electron transport through dense plasmas is presented. It is found that, using quasi-realistic electron populations, it is possible to generate shock waves with peak pressures that agree with a simple scaling law and have sustained shock pressures of several hundred Mbars. However, the spatial and temporal scales required for shock waves to fully develop increase with fast electron temperature and can become significant. Careful consideration of this effect is needed when assessing their usefulness as shock wave drivers. A characteristic time of shock wave formation is reinterpreted as the definitive time taken for a localised source of internal energy in an otherwise uniform fluid to drive a blast wave containing its maximum kinetic energy. This relation is of utility in inertial confinement fusion where ignition relies on the conversion of kinetic energy to internal energy at implosion stagnation. However, it is not straightforwardly reproducible by fast electron heating, which highlights the difficulties that may be encountered if fine control over shock wave formation is required. The shape of the density profile seems to be of secondary importance when compared with the consequences of heating using hotter electron populations. When heating times are on the time scale of the ignitor pulse, the density profile affects the efficiency of shock wave formation by determining the transition from an explosive regime to a driven regime of shock wave forma- tion. However, the time taken for the shock wave to contain its maximum kinetic energy is not significantly affected. It is shown that an externally applied magnetic field can constrain the range of fast electrons in solid density planar plastic targets, and enhance localised energy deposition. This mitigates the need for significant spatial and temporal scales when using fast electron populations with extended energy distributions to drive shock waves. However, this comes at the expense of the strength of the shock wave.
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Bourne, Neil Kenneth. "Shock wave interactions with cavities." Thesis, University of Cambridge, 1990. https://www.repository.cam.ac.uk/handle/1810/250963.
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Mäkinen, Kjell. "Underwater shock loaded sandwich structures /." Stockholm, 1999. http://www.lib.kth.se/abs99/maki0326.pdf.
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Eliasson, Veronica. "On focusing of shock waves." Doctoral thesis, Stockholm : Mekanik, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4479.
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Naumann, Michael. "MEMS reliability in shock environments." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-117360.
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In der vorliegenden Arbeit wird eine Methode vorgestellt, mit welcher die Zuverlässigkeit mikroelektromechanischer Systeme (MEMS) bezüglich stoßinduzierter Fehlermechanismen bereits in der Entwurfsphase neuer Produkte abgeschätzt bzw. verbessert werden kann. Der Ansatz bezieht sich dabei auf bruch- sowie adhäsionsbedingte Ausfallmechanismen und erfordert zwei wesentliche Schritte. Zuerst werden Systemmodelle der jeweils zu untersuchenden mikromechanischen Systeme erstellt, welche die Berechnung der Stoßantwort wie auch der dabei auftretenden Belastungen in Sinne von Auslenkungen, Deformationen und Aufprallkräften ermöglichen. In einem zweiten Schritt wird die zur Fertigung vorgesehene Technologie bezüglich des Auftretens beider stoßbedingter Ausfallmechanismen sowie deren Abhängigkeit von verschiedenen Umgebungsbedingungen oder Betriebsparametern systematisch untersucht. Die aus der Prozesscharakterisierung resultierenden Daten dienen zur Ableitung prozessspezifischer Fehlerkriterien, welche die Einschätzung der zuvor berechneten Lasten ermöglichen. Auf diese Weise kann abgeschätzt werden, inwieweit die Zuverlässigkeit der betrachteten mikromechanischen Strukturen beeinflusst wird bzw. mit welchen Maßnahmen diese gesteigert werden kann.
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Lee, Donggeol. "Culture shock : video interview project." Virtual Press, 2007. http://liblink.bsu.edu/uhtbin/catkey/1371470.
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This project is for Rinker Center for International Programs at Ball State University to provide useful information to international and American students. The project consists of ten video interviews with the director of Rinker Center for International Programs and nine international students presenting Ghana, France, Germany, Mexico, Brazil, Japan, China, Taiwan, and Turkey. Each interviewee provides cultural differences between American culture and their cultures. In addition, the interviewees tell their personal solutions for coping with cultural difficulties based on their experiences in the United States or different cultures. The director was given three questions and the nine international students were asked ten questions.Each video interview is categorized under country menus and question menus designed with Adobe Macromedia Flash 8 to be navigated by clicking each menu button on a computer.Department of Telecommunications
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Lennon, Francis. "Shock wave propagation in water." Thesis, Manchester Metropolitan University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240559.
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Herrera, Montojo Javier. "Shock estimation in supersonic vehicles." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28628.
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Improving the design of future high-Mach vehicles is crucial to enhance performance,safety and sustainability of future air travel. Advanced designs can be realized by improving low fidelity modelling in the context of Multidisciplinary Design Optimization (MDO) on one side and making the use of high fidelity tools more efficient in the context of Multi-fidelity Design Approaches (MFDA) on the other. This thesis presents the formulation of an advanced low order model for the estimation of the shock structure generated by vehicles flying in the supersonic and hypersonic regimes. Taking as inputs the geometry and the flow conditions, the proposed approach addresses, in one cohesive methodology, attached and detached shocks in two and three dimensions as well as shock structures composed of multiple shocks. The procedure is based on classical supersonic flow theories and has been verified against computational fluid dynamics simulations. The proposed methodology allows for a cost-effective estimation of shock wave patterns and their impingement on the vehicle surface on one side, while on the other it can be used to realize a-priori shock-fitted meshes reducing someof the uncertainty while generating them for high-fidelity CFD simulations.
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Ekbal, N. J. "NADH monitoring in shock states." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1463985/.
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Shock is defined as inadequate delivery or utilization of oxygen by the body tissues. Currently measured cardiorespiratory variables however, indicate decompensation only when patients become (near) shocked. Belated intervention often fails to reverse injury, leading to organ dysfunction and failure. Precise monitoring of the adequacy of tissue perfusion thus represents a major deficiency in clinical practice, particularly in the critically ill. As mitochondria utilize >90% of the oxygen consumed by the body, predominantly for ATP production, there is an obvious logic in targeting this organelle for monitoring the adequacy of tissue perfusion. Within mitochondria, NADH transfers electrons from the Krebs’ cycle to Complex I of the electron transport chain. In doing so, NADH is oxidized to NAD+. A rise in NADH:NAD+ ratio (redox state) will occur with a downstream block in the chain, e.g. due to lack of oxygen. As NADH (but not NAD+) fluoresces in response to UV light excitation (340nm), with an intensity relating to its concentration, and as most of the NADH signal represents changes in mitochondrial NADH, this property may be utilized for non-invasive assessment of tissue hypoperfusion. I validated the technique in vitro, and investigated its utility in rat shock models. During graded or abrupt decreases in the constituent parts of tissue oxygen delivery (cardiac output, haemoglobin and oxyhaemoglobin saturation), as well as during resuscitation, I assessed the relationship between skeletal muscle NADH fluorescence intensity, organ perfusion and oxygenation. I compared these against measures of global haemodynamics and tissue perfusion routinely measured in critically ill patients. With each graded insult, NADH fluorescence demonstrated increases reflecting severity of the insult, with improvements upon resuscitation. A persisting rise in NADH fluorescence >50% above baseline foretold death within the following 30-45 minutes, in advance of the other monitored variables. My results indicate that NADH fluorescence may be used for monitoring tissue hypoperfusion in shock states, and as a guide to the timing and adequacy of therapeutic interventions.
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Ledezma, Ramirez Diego Francisco. "Shock isolation using switchable stiffness." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/64538/.
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This study investigates a novel stiffness control strategy applied to the problem of shock isolation. This is based on the principle that the stiffness and mass are the principal physical properties that control the passive system shock response. The problem of shock response control is divided in two stages. Firstly, the maximum response whilst a shock is applied is considered, and the effectiveness of a switchable isolation stiffness strategy is evaluated. This strategy aims to reduce the shock response by switching the stiffness to a low value during the shock input. Two different models are considered for the theoretical analysis, namely, a single mass supported by two elastic elements one of which can be disconnected, and a second model where the switchable element comprises a secondary mass-stiffness system. The performance of the two strategies is analyzed in terms of response parameters such as the absolute and relative displacement and absolute acceleration. The single degree-of-freedom system is considered as a benchmark for comparison. The issue of residual vibration suppression is then presented. For the latter a different switchable stiffness strategy is identified, and the analysis is mainly concerned with the energy dissipation mechanism used to suppress residual vibration. As in the first stage of shock isolation, two models are considered. Optimum configurations and stiffness changes are identified for both the shock response reduction and the decay of the residual vibration. The effect of viscous damping is subsequently incorporated. The practical implementation and experimental validation is then presented and a experimental system is developed. It is based on a conceptual model comprising a magnetic suspension element that is able to change its effective stiffness by altering the magnetic force. This novel configuration has the advantages of achieving a high stiffness change in a very short amount of time and with very low damping, which is required to validate the theoretical studies. The design and properties of the model are discussed and then both stiffness strategies are implemented. This model is used to show the feasibility and evaluate the isolation performance of the different switchable stiffness strategies and the issues and limitations of the implementation.
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Barker, Bryn Nicole. "Stability of MHD Shock Waves." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8437.
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This thesis focuses on the study of spectral stability of planar shock waves in 2-dimensional magnetohydrodynamics. We begin with a numerical approach, computing the Lopatinski determinant and Evans function with the goal of determining if there are parameters for which viscous waves are unstable and the corresponding inviscid waves are stable. We also begin developing a method to obtain an explicit, analytical representation of the Evans function. We demonstrate the capabilities of this method with compressible Navier-Stokes and extend our results to 2-D MHD. Finally, using compressible Navier-Stokes again, we derive an energy estimate as a first step in improving the bound on possible roots of the Evans function.
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Besperát, Tomáš. "Marketingová strategie značky BIG SHOCK!" Master's thesis, Vysoká škola ekonomická v Praze, 2011. http://www.nusl.cz/ntk/nusl-149847.
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Diploma thesis analyses current marketing strategy of Big Shock! brand, active on the energetic products market. It includes competition monitoring, consumer behaviour study and the latest trends on the energy drinks market in the Czech Republic. Part of the thesis is based on my own quantitative on-line research among energy drinks consumers. The conclusion contains current strategy analysis and some recommendations ensuing either of the market development and research made.
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Hassinger, Elaine. "Shock-Chlorination of Domestic Wells." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1994. http://hdl.handle.net/10150/156938.
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1 pp.Shock-chlorination is an effective way to disinfect your well and household plumbing. You should shock-chlorinate your well after repairing it, or, if a lab test shows there are coliform bacteria in the water. This publication explains how shock-chlorination works and the steps needed to use this treatment.
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Fagelson, Marc A. "Grand Rounds: Acoustic Shock Disorder." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/5410.
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This highly popular session will focus on presentation of case studies from adult patients. Particular emphasis will be placed on assessment and management of patients with challening and unique auditory and vesitbular disorders. A wide range of disorders has been selected. Presentation have been designed to stimulate interest and conversation regarding novel diagnostic and treatment approaches for the adult population. Audience participation is highly encouraged. Presentations were solicited invitation.
Learning Objectives: Upon completion, participants will be able to discuss the role of concussion and traumatic brain injury in hearing and listening evaluation and treatment Upon completion, participants will be able to discuss the importance evaluating auditory processing in individuals with normal peripheral hearing sensitivity who present with auditory complaints. Upon completion, participants will be able to discuss the impact of migraine on management of a patient with positional vertigo, dizziness, and tinnitus.
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Frazer, Brett Graeme. "Analysis of shock compacted zirconia." Thesis, Queensland University of Technology, 1999.
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Eichmann, Troy N. "An experimental investigation of shock shapes and shock stand-offs in a super-orbital facility /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18122.pdf.
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Rosten, Patricia Melanie. "The role of toxic shock syndrome toxin-1 in the pathogenesis of toxic shock syndrome." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26527.
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Toxic shock syndrome toxin-1 (TSST-1), an exoprotein produced by some strains of Staphylococcus aureus, is implicated in the pathogenesis of menstrual TSS. However, its role in nonmenstrual TSS is less certain. In order to study the pathogenetic role of TSST-1 in TSS, three approaches were taken: a) to develop an ELISA for detection of TSST-1 in biologic fluids in order to verify TSST-1 production in vivo in TSS patients, b) to quantitate TSST-1 specific antibodies in the serum of TSS patients and controls to determine whether such antibodies are protective, and c) to attempt to identify other staphylococcal products which may be implicated in some forms of TSS.
A sensitive and specific noncompetitive enzyme-linked immunosorbent assay (ELISA) capable of detecting TSST-1 at concentrations from 0.5 to 16 ng/ml was developed. This assay did not detect other staphylococcal enterotoxins including A, B, C₁, C₂, C₃, D and E. Possible interference by protein A was readily eliminated by pretreatment of test samples with 10% nonimmune rabbit serum. The assay was adapted for rapid screening of TSST-1 production by S. aureus isolates in culture supernatants in vitro, and for the detection of TSST-1 in vaginal washings and urine of TSS patients and healthy controls in vivo. All 35 S. aureus isolates confirmed to be TSST-1 positive by Ouchterlony immunodiffusion, and 59 of 60 isolates confirmed to be TSST-1 negative, gave concordant results by ELISA. Interestingly, toxigenic S. aureus strains isolated from TSS patients quantitatively produced significantly more toxin in vitro compared to toxigenic control strains (p<0.05, Mann-Whitney rank sum test). TSST-1 could be detected by ELISA in 3 of 4 vaginal washings collected within 3 days of hospitalization from 3 women with acute menstrual TSS, compared to 0 of 17 washings from 9 TSS women collected greater than 3 days after hospitalization (p=0.003, Fisher's exact test) and 1 of 15 washings from 14 healthy control women (p=0.016). TSST-1 was not detected in the urine of 4 acute TSS patients, 2 convalescent TSS patients or in 3 control urine tested.
A sensitive and reproducible ELISA was also developed for the quantitation of TSST-1 specific IgG in serum. Anti-TSST-1 was assessed in acute and convalescent sera from 16 nonmenstrual (9 female, 7 male) and 14 menstrual TSS patients, and from 87 healthy women and 66 healthy men as controls. Quantitative levels of anti-TSST-1 in the study groups were calculated as the percent of standard activity (POSA) relative to a medium titre reference serum standard. ELISA titers in acute sera from menstrual TSS (26.2 ± 5.2, mean POSA ± S.E.M.), but not nonmenstrual TSS women (71.8 ± 18.6), were significantly lower than in healthy controls (78.9 ± 7.3) (p<0.01, Mam-Whitney test). Titers from menstrual TSS patients remained low (25.2 ± 10.7) even during late convalescence (mean duration 20 months after illness onset), compared to healthy female controls (p<0.05). Acute titers in males with TSS (37.0 ± 15.6) were also significantly lower than those in control men (114.6 + 11.0) (p<0.05). An inverse relationship of recovery of toxigenic S. aureus and anti-TSST-1 titers in acute sera of TSS patients was observed. Interestingly, antibody titers in control men were significantly higher than in control women (p<0.001). No age-dependent effects or interactive effects of age and sex on ELISA titers were observed.
To enable immunoblot analyses, TSST-1 was produced and partially purified using column chromatography techniques. Percent recovery of TSST-1 from culture supernatant through to the final procedure was approximately 15.5%. The relative purity of TSST-1 (TSST-l/total protein, w/w) was increased from 0.21% in culture supernatants to 94.4% in the final product. Ouchterlony immunoprecipitation against reference rabbit antitoxin demonstrated identity with reference TSST-1 as well as with TSST-1 prepared in other laboratories. Physical characterization demonstrated a molecular weight of 24 kd and a pi of 7.0. Using pooled normal human serum as a first antibody probe, several bands in addition to the 24 kd TSST-1 band were visualized by immunoblot against our partially purified toxin as well as similar preparations obtained from other investigators. To determine whether any of the additional bands might be implicated in TSS, acute and convalescent sera from TSS patients were used to probe for immunoreactive bands in our partially purified TSST-1 as well as a commercially obtained preparation. Seroconversion was demonstrated to the 24 kd TSST-1 protein in 7 of 10 TSS patients from whom toxigenic S. aureus was isolated. In addition, seroconversion was noted to a 49 kd band in 4 patients, to a 21 kd band in 3 patients, to a 28 kd band in 1 patient and to a 32 kd band in 2 patients.
In conclusion: 1) the ability to measure TSST-1 in biologic fluids lends stronger support for the role of TSST-1 in menstrual TSS patients; 2) the serologic data support the etiologic role of TSST-1 in menstrual TSS and in nonmenstrual TSS patients from whom toxigenic S. aureus could be cultured, but not for nonmenstrual TSS women from whom toxigenic S. aureus was not isolated; 3) immunoblotting results with acute and convalescent sera from TSS and control patients, not only add further support to the role of TSST-1 in patients from whom toxigenic S. aureus could be isolated, but also indicate that there may be several other staphylococcal products implicated in TSS, particularly in whom antibody to TSST-1 pre-existed in acute sera. The nonresponsiveness or lack of seroconversion to TSST-1 in some patients could suggest either: a) TSST-1 was not the etiologic agent for such patients; b) TSST-1 was the etiologic agent, but the exposure was sufficient for an immune response (similar to tetanus), or; c) some immunologic defect may be present. Future studies are required to clarify these possibilities.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
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Joplin, Karl H. "Protein expression in flesh flies (Sarcophaga) in response to heat shock, cold shock and diapause /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487668215807964.
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Stevens, Meredith Leigh. "Global repression of non-heat shock gene transcription by activation of heat shock factor in Drosophila." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0004/MQ46197.pdf.
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Hilmarsson, Brynjar. "Shock Absorbing Flooring For Elderly Homes : Study of Shock Absorption of Head Impacts and Rolling Resistance." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-244871.
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In Sweden fall-related injuries among the elderly lead to over a thousand deaths and close to 300.0000 hospital visitations annually. Fall related injuries can in many cases lead to serious head injuries along with other fractures. The elderly are more prone to fall and sustain an injury because of conditions such as osteoporosis and weak muscles. Researchers at KTH from the Division of Neuronic Engineering have developed a special floor that absorbs energy from an impact which can reduce the severity of injury when a person falls. There has been research done on the floor focusing on hip fractures which have shown good results. The floor has been set up in an elderly home in Stureby, Stockholm, Sweden, however further testing is needed to fully develop the floor to its maximum capacity. One goal of this master thesis was to investigate certain obstacles with the floor which arose during testing in Stureby. One of the challenges was that the floor had greater rolling resistance since it is softer than a normal concrete floor. The experiment was done by using a dynamo meter to measure the force needed to move a test wagon with a fixed weight and different sizes of wheels. Another goal of this thesis was to investigate head impacts on the KTH floor. That was done in a helmet testing lab at Mips helmet company. There a dummy head was dropped from various heights and the acceleration was measured. The 1st principle strain of the brain was calculated from the collected data. Other companies have created similar floors so it was a part of the thesis to compare the KTH floor with its competitors. The results from the rolling resistance showed that by increasing the width and diameter of the wheels there was less force needed to move the test wagon. Further tests are needed to investigate the problem regarding the indentation issues seen on the floor set up in Stureby. Some research has already begun with different types of linoleum and glue. In the head impact studies, the KTH floor showed the best results of all tested floors when dropped from 60 cm. However, when dropped from 100 cm a competitor floor showed better results in the resultant translational acceleration.
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Matsuda, Tomoko. "Suppression of Heat Shock Protein-70 by Ceramide in Heat Shock-induced HL-60 Cell Apoptosis." Kyoto University, 2003. http://hdl.handle.net/2433/148483.
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Tazir, Yasmina. "Strongyloides ratti : identification, isolation and characterisation of Heat Shock Protein 10 and Heat Shock Protein 60 /." Giessen : VVB Laufersweiler, 2009. http://d-nb.info/99845494X/04.
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Risner, Christopher D. "Development of Cal Poly's Shock Table." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1677.
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Shock is one of the environmental tests that a spacecraft must pass before being cleared for launch. Shock testing poses a challenging data acquisition issue and careful selection of equipment is crucial to creating a successful shock test facility. Cal Poly’s CubeSat programs can currently perform all environmental testing other than shock themselves, so a quality shock table would be useful. Previous groups of students had developed a shock table, and this paper details the improvement and characterization of that shock table’s behavior. Several adjustable parameters were tested and documented to discover trends in the shock table’s response to an impact from a pendulum hammer. Then a test meant to mimic an actual shock test was performed. The CubeSat program provided a component to be tested and a requirement to be met. The nominal requirement is proprietary and cannot be given here, and additional stipulations included the test data being within a given tolerance band and at least 50% of the test data having a larger magnitude than the nominal requirement. The requirement needed to be met in all three of the component’s axes. The component was mounted to the shock table and acceleration data was collected and analyzed. A successful test was conducted in one axis, which was the result of impacting the large face of the aluminum shock table plate. The tests in the other two axes, conducted with impacts to the side of the aluminum plate, failed to meet the requirement. A finite element model of the table was developed and correlated to the test data. A new way of attaching the test component to the table was developed that would allow for testing in all three axes to be performed with impacts to the large face of the aluminum plate. A dynamic finite element analysis was performed, and the results indicate that this new attachment method should allow the requirement to be met in all three axes. The shock table is currently fully operational and can be used for testing and teaching purposes. With the implementation of the new attachment method, it is believed that the CubeSat program’s requirements can be met as well.
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Ernst, Scott. "A nonlinear investigation of corrugation instabilities in magnetic accretion shocks." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11229.
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xi, 172 p. : ill. (some col.)Accretion shock waves are present in many important astrophysical systems and have been a focus of research for decades. These investigations provide a large body of understanding as to the nature, characteristics, and evolutionary behaviors of accretion shock waves over a wide range of conditions. However, largely absent are investigations into the properties of accretion shock waves in the presence of strong magnetic fields. In such cases these strong magnetic fields can significantly alter the stability behaviors and evolution of the accretion shock wave through the production and propagation of magnetic waves as well as magnetically constrained advection. With strong magnetic fields likely found in a number of accretion shock systems, such as compact binary and protostellar systems, a better understanding of the behaviors of magnetic accretion shock waves is needed. A new magnetohydrodynamics simulation tool, IMOGEN, was developed to carry out an investigation of instabilities in strong, slow magnetic accretion shocks by modelling their long-term, nonlinear evolution. IMOGEN implements a relaxed, second-order, total variation diminishing, monotonic upwind scheme for conservation laws and incorporates a staggered-grid constrained transport scheme for magnetic advection. Through the simulated evolution of magnetic accretion shocks over a wide range of initial conditions, it has been shown, for sufficiently high magnetic field strengths, that magnetic accretion shocks are generally susceptible to corrugation instabilities, which arise in the presence of perturbations of the initial shock front. As these corrugation instabilities grow, they manifest as magnetic wave propagation in the upstream region of the accretion column, which propagate away from the accretion shock front, and as density columns, or fingers, that grow into the higher density downstream flow, defined and constrained by current loops created during the early evolution of the instability.
Committee in charge: Dr. James Schombert, Chair; Dr. James Imamura, Advisor; Dr. Alan Rempel, Member; Dr. John Toner, Member; Dr. Kent Stevens, Outside Member
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Kankkunen, Erika. "Cognitive ability and transitory productivity shocks." Thesis, Uppsala universitet, Nationalekonomiska institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388373.
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People who live in rural areas in low-income countries not only live in poverty, they also have to deal with an extremely variable income. In the absence of a well-functioning credit market, these fluctuations can be costly for households. This study aims to provide knowledge to the cost of these fluctuations, more precisely the study aims to answer how transitory weather shocks in Kenya affect children´s cognitive ability. Where weather shocks are assumed to be aggregated shocks that temporarily change the productivity in districts. The result from the study shows that drought, which can be seen as a negative shock, decrease the cognitive ability of children 11 to 16. The effect is marginally significant at the 10 percent level. No significant effect on cognitive ability is found for children aged 6 to 10. The result for older children is robust to alternative specifications. The study does not show any conclusive evidence on different effects on how boys and girls are affected by droughts.
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Casoni, Rero Eva. "Shock capturing for discontinuous Galerkin methods." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/51571.
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Aquesta tesi doctoral proposa formulacions de Galerkin Discontinu (DG) d’alt ordre per la captura de shocks, obtenint alhora
solucions altament precises per problemes de flux compressible.
En les últimes dècades, la investigació en els mètodes de DG ha estat en constant creixement. L'èxit dels mètodes DG en
problemes hiperbòlics ha conduit el seu desenvolupament en lleis de conservació no lineals i problemes de convecció dominant.
Entre els avantatges dels mètodes DG, destaquen la seva estabilitat inherent i les propietats locals de conservació. D'altra banda,
els mètodes DG estan especialment dissenyats per l’ús aproximacions d'ordre superior. De fet, en els últims anys s'ha demostrat
que la resolució de problemes de convecció dominant ja no es restringeix només a elements d'ordre inferior. De fet, es necessiten
models numèrics d'alta precisió per aconseguir prediccions altament fiables dins la dinàmica de fluids computacional (CFD). En
aquest context es presenten i discuteixen dos tècniques de captura de shocks.
En primer lloc, es presenta una tècnica novedosa i senzilla basada en la introducció d'una nova base de funcions de forma. Aquesta
base té la capacitat de canviar a nivell local entre una interpolació contínua o discontínua, depenent de la suavitat de la funció que
es vol aproximar. En presència de xocs, les discontinuïtats introduïdes dins l’element permeten incloure l'estabilització necessària
gràcies a l’ús dels fluxos numèrics, i alhora exploten les propietats intrínsiques del mètodes DG. En conseqüència, es poden utilitzar
malles grolleres amb elements d’ordre superior. Amb aquestes discretitzacions i, utilitzant el mètode proposats, els xocs queden
continguts a l’interior de l’element i per tant, és possible evitar l’ús de tècniques de refinament adaptatiu de la malla, alhora que es
manté la localitat i compacitat dels esquemes DG.
En segon lloc, es proposa una tècnica clàssica i, aparentment simple: la introducció de la viscositat artificial. Primerament es realitza
un estudi detallat per al cas unidimensional. S’obté una viscositat d’alta precisió que escala segons el valor hk amb 1 ≤ k ≤ p i essent
h la mida de l’element. En conseqüència, s’obté un xoc amb amplitud del mateix ordre. Seguidament, l'estudi de la viscositat
unidimensional obtenida s'extén al cas multidimensional per a malles triangulars. L'extensió es basa en la projecció de la viscositat
unidimensional en unes determinades direccions espacials dins l’element. Es demostra de manera consistent que la viscositat
introduïda és, com a molt, del mateix ordre que la resolució donada per la discretització espacial, és a dir, h/p. El mètode és
especialment eficient per aproximacions de Galerkin discontinu d’alt ordre, per exemple p≥ 3.
Les dues metodologies es validen mitjançant una àmplia selecció d’exemples numèrics. En alguns exemples, els mètodes
proposats permeten una reducció en el nombre de graus de llibertat necessaris per capturar xocs acuradament de fins i tot un ordre
de magnitud, en comparació amb mètodes estàndar de refinament adaptatiu amb aproximacions de baix ordre.This thesis proposes shock-capturing methods for high-order Discontinuous Galerkin (DG) formulations providing highly accurate solutions for compressible flows. In the last decades, research in DG methods has been very active. The success of DG in hyperbolic problems has driven many studies for nonlinear conservation laws and convection-dominated problems. Among all the advantages of DG, their inherent stability and local conservation properties are relevant. Moreover, DG methods are naturally suited for high-order approximations. Actually, in recent years it has been shown that convection-dominated problems are no longer restricted to low-order elements. In fact, highly accurate numerical models for High-Fidelity predictions in CFD are necessary. Under this rationale, two shock-capturing techniques are presented and discussed. First, a novel and simple technique based on on the introduction of a new basis of shape functions is presented. It has the ability to change locally between a continuous or discontinuous interpolation depending on the smoothness of the approximated function. In the presence of shocks, the new discontinuities inside an element introduce the required stabilization thanks to the numerical fluxes, thus exploiting DG inherent properties. Large high-order elements can therefore be used and shocks are captured within a single element, avoiding adaptive mesh refinement and preserving the locality and compactness of the DG scheme. Second, a classical and, apparently simple, technique is advocated: the introduction of artificial viscosity. First, a one-dimensional study is perfomed. Viscosity of the order O(hk) with 1≤ k≤ p is obtained, hence inducing a shock width of the same order. Second, the study extends the accurate one-dimensional viscosity to triangular multidimensional meshes. The extension is based on the projection of the one-dimensional viscosity into some characteristic spatial directions within the elements. It is consistently shown that the introduced viscosity scales, at most, withthe DG resolutions length scales, h/p. The method is especially reliable for highorder DG approximations, say p≥3. A wide range of different numerical tests validate both methodologies. In some examples the proposed methods allow to reduce by an order of magnitude the number of degrees of freedom necessary to accurately capture the shocks, compared to standard low order h-adaptive approaches.
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Carter, John P. "Magnetic field generation in shock waves." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://edocs.nps.edu/npspubs/scholarly/theses/1994/June/94Jun_Carter.pdf.
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Ahmed, Syed Muzaffor. "Molecular Shock Structure in Multifluid MagnetohydrodynamicS." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486150.
Full textAbstract:
We present an investigation on the effects of magnetic dissipation and cooling due to spontaneous radiative emission in multifluid magnetohydrodynamic (MHD) shocks. Ideal MHD allows n small amplitude waves and therefore we can associate a shock with each. But, only non-linear fast and slow shocks are evolutionary. On smaller scales the structure ofshocks is determined by the non-ideal MHD equations and from neutral cooling. Therefore in a dense weakly ionised medium there exist three generic types of shock; C-type, J-type and C*-type. The shooting method can be used to calculate simple steady solutions, with constant ambipolar resistivity and radiative cooling. In this approach only coplanar transverse fields can vary i.e., these shocks are coplanar. But, this method is restricted to C-type non-reacting fluid· shocks, since J-type and C*-type contain a point of singularity in the transonic phase. For time dependent equations an upwind conservative scheme (Godunov's scheme) in one dimension is used. This method is less restricted; we have shown that it is extremely accurate in second order and that we call also capture all three generic interstellar shocks successfully. For completeness we : give expressions for the sources of mass, momentum and energy in a five fluid reacting model. We show that studies in zero dimensions can be used to reveal important shock structure parameter.s. Five fluid MHD shocks show that ionisation, recombination and . grain dynamics can have profound effects on the structure. Firstly we show that slow shock length scales are significantly enhanced and that cooling from molecular rotational and atomic fine structure lines contributes significantly in fast shocks. Thus the structure of the weakest and strongest shocks are characteristically adiabatic and characteristically finite cooling respectively. Conditions are such that both ambipolar resistivity and Hall resistivity can dominate, hence the waves are characteristically dissipative and dispersive, but, only in the fast regime a significant non-coplanar transverse field is induced. In slow shocks grain fluids are decoupled from the field, but in the fast regime they can reconnect· with the field and this is also dependent on their dimensions. We predict that slow shocks are generally C*-type, and that such shocks are more likely to be responsible for the: condensation of dense cores and therefore the formation of protostellar objects and stars.
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Karnick, Pradeepa Tumkur. "Shocks, Shock-Boundary Layer Interaction, And Transonic Flutter." Thesis, 2014. http://etd.iisc.ac.in/handle/2005/2688.
Full textAbstract:
Transonic utter is an aeroelastic instability characterized by part-chord shocks over an airfoil and single mode oscillations leading to a drop in the utter boundary. We present a numerical study that examines the influence of shocks, shock-boundary layer interactions, and three-dimensional flow features on the transonic utter boundary. Using energy concepts we show that shocks and shock-boundary layer interactions have a profound influence on the stability of an aeroelastic system. Viscosity stabilizes the aeroelastic system through thickness effects up-to the bottom of the transonic dip. Beyond, shock induced separation not only stalls the aeroelastic system, but also makes it oscillate about a new equilibrium position. In this region, where viscous effects are dominant, the inviscid utter boundary shows multiple utter points. Modal contributions to the response of the aeroelastic systems |viscous and inviscid | indicate that viscosity restricts higher mode participation. Restriction of higher modes by viscosity is responsible for the elimination of multiple utter points that are present in the inviscid case. Multiple forcing frequencies are observed in those regions of the utter boundary where viscous effects are dominant. Further, the shock dynamics exhibit shock-reversal where-in the shock motion predicted by the viscous simulation is 180_ out of phase relative to that of the inviscid case. At Mach numbers beyond the shock-stall region the shock moves close to the trailing edge of the airfoil, and inviscid and viscous simulations predict almost a similar utter boundary. Three-dimensional transonic flow structures on a finite-span wing aeroelastic model de-stabilizes it relative to an equivalent two-dimensional model.
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Karnick, Pradeepa Tumkur. "Shocks, Shock-Boundary Layer Interaction, And Transonic Flutter." Thesis, 2014. http://etd.iisc.ernet.in/handle/2005/2688.
Full textAbstract:
Transonic utter is an aeroelastic instability characterized by part-chord shocks over an airfoil and single mode oscillations leading to a drop in the utter boundary. We present a numerical study that examines the influence of shocks, shock-boundary layer interactions, and three-dimensional flow features on the transonic utter boundary. Using energy concepts we show that shocks and shock-boundary layer interactions have a profound influence on the stability of an aeroelastic system. Viscosity stabilizes the aeroelastic system through thickness effects up-to the bottom of the transonic dip. Beyond, shock induced separation not only stalls the aeroelastic system, but also makes it oscillate about a new equilibrium position. In this region, where viscous effects are dominant, the inviscid utter boundary shows multiple utter points. Modal contributions to the response of the aeroelastic systems |viscous and inviscid | indicate that viscosity restricts higher mode participation. Restriction of higher modes by viscosity is responsible for the elimination of multiple utter points that are present in the inviscid case. Multiple forcing frequencies are observed in those regions of the utter boundary where viscous effects are dominant. Further, the shock dynamics exhibit shock-reversal where-in the shock motion predicted by the viscous simulation is 180_ out of phase relative to that of the inviscid case. At Mach numbers beyond the shock-stall region the shock moves close to the trailing edge of the airfoil, and inviscid and viscous simulations predict almost a similar utter boundary. Three-dimensional transonic flow structures on a finite-span wing aeroelastic model de-stabilizes it relative to an equivalent two-dimensional model.