Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 28 for “"Critical velocity"”.
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Critical Velocity is Associated with Combat Specific Performance Measures in a Special Forces Unit
… It provides two performance estimates, critical velocity (CV) and anaerobic distance capacity (ADC). CV provides a measure of the individual's aerobic capacity, while the ADC is an indicator of anaerobic capacity. The purpose of this study, therefore, is to examine the relationship …
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Computational fluid dynamics (CFD) modelling of critical velocity for sand transport flow regimes in multiphase pipe bends.
… - including the sand segregation, deposition velocity and flow turbulence modulation in the pipe bend - show that the seemingly small pipe bends have a significant effect on the flow, which is different to that of horizontal pipes. The pipe bend causes an abrupt local change in the multiphase …
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Frictional oscillations in elastomeric sliding
… steady state sliding as a function of load and velocity were experimentally determined. Stick-slip, the dominant mode of unsteady sliding did not occur below a critical velocity. The effects of surface energy, surface roughness and temperature on the critical velocity for stick-slip were also …
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Model for the onset of nonlinear flow dissipation in 2D superfluid helium films
… Halperin, Nelson, and Siggia to include to flow velocity. The renormalization group calculation is carried out on a computer to determine the dissipation as a function of superfluid velocity. We find the onset of nonlinear dissipation is driven by two mechanisms whose relative contributions are …
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Critical flow velocity in super fluid 3He-B
… an object in uniform linear motion at the Landau critical velocity. The experiments were performed in a “Lancaster style” nested experimental cell at ultra-low temperatures within the ballistic limit. In the first set of experiments we studied two almost identical quartz tuning fork resonators …
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Nonlinear Investigation of the Use of Controllable Primary Suspensions to Improve Hunting in Railway Vehicles
… in rail vehicle dynamics. Sensitivity of the critical hunting velocity to various primary and secondary stiffness and damping parameters has been examined. This research assumes the rail vehicle to be moving on a smooth, level, and tangential track, and all parts of the rail vehicle to be …
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Multi-axial failure of high-performance fiber during transverse impact
… shape, with an emphasis set on determining the critical velocity wherein below said velocity significant development of wave propagation occurs and above said velocity the yarn fails immediately upon impact. In actuality, a range rather than a stark jump defines this critical velocity and as …
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Frictional vibrations in structural polymers
… roughness, internal lubrication, friction-velocity relationships, and system stiffness. Four basic types of frictional behavior were observed - steady sliding, a single stick followed by steady sliding, non-sustained stick-slip oscillations that decayed after several oscillations, and …
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Factors related to cycling performance
… variables. The testing variables measured were critical velocity (CV), Conconi anaerobic threshold (AT) velocity, 4mM AT velocity, fatigue index, peak blood lactate, and anaerobic work capacity. Participants were USCF 30 category 1 through 5 cyclists. Participants performed one 20.75 km and two …
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Mechanisms of secondary dispersions separation in particulate beds
… effect of packed height and packing size upon critical velocity, pressure drop and coalescence efficiency have been investigated. Single and two phase flow pressure drops across the packing were correlated by modified Blake-Kozeny equations. Two phase pressure drop was correlated by two …
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Interactions between water-based fixed fire-fighting systems and longitudinal ventilation in road tunnels
… to the off-fire interactions, with which the critical velocity and air-driving force reductions due to the suppression are investigated. For the impact of ventilation on the WFFFS, the objective is to investigate the activation delay of temperature-triggered automatic nozzles, which requires a …
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Erosion behavior and scour risk of extremely coarse streambeds
… research is to develop a relationship between critical (entrainment) velocity and grain size for sediment particles in the size range of 5 to 50 cm (2 to 20 in). This is accomplished by performing a limit analysis of sediments that exist within the stream beds of actual bridges. A basic premise …
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Multiscale hybrid simulation of brittle fracture
… of a fracture instability which onsets below a critical velocity, and shows how subtle atomistic details at the crack tip can control the qualitative macroscopic fracture behaviour.
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Dynamics of finite momentum Bose polarons
… state phase transition when the impurity has a velocity greater than that of the sound velocity (Landau critical velocity) associated with Bogoliubov quasiparticle excitations of the BEC. As we cross from the subsonic regime to the supersonic regime, we get a breakdown of the polaron …
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Stability analysis of partially filled tanker trucks using a finite element modeling approach
… simulations are made to determine the critical velocity for the given maneuver. These are presented for a constant radius turn and for double lane change maneuvers.
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Demagnetisation of solid 3He and supercritical superflow
… linear motion. An object moving with high enough velocity that the excitation spectrum becomes gapless can create excitations at no energy cost and initiate the breakdown of the condensate - this limit is the well-known Landau velocity. In superfluid 3He, flow around an oscillating body displays a …
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Quasiparticle beam profile measurements in superfluid helium 3 - B
… slightly higher than the pair-breaking critical velocity which spreads out at higher velocities. At 21 mm/s the vibrating resonator is found to have a more focused beam than the Black-Body radiator where both beam profiles are found to be focused around the centre of the quasiparticle …
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The sliding wear of polymers against steel
… data for polymeric materials sliding at constant velocity against a hardened stainless steel base. The polymers investigated were ultra high molecular weight polyethylene (UHMWPE), ultra high molecular weight polyethylene-with a friction reducing additive (UHMWPE/FILL), polyoxymethylene (POM), …
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Resistance of a granular medium to normal impact of a rigid projectile
… almost exclusively been based upon the impact velocity and the corresponding maximum penetration. In this research, the motion of the projectile during the penetration process was obtained by utilizing microwaves. The motion characteristics were obtained by "bouncing" microwave signals from the …
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Dynamische Stabilisierung von Hochgeschwindigkeitswolken im galaktischen Halo
HI observations of high-velocity clouds (HVCs) indicate that they are interacting with their ambient medium. In this thesis, the question on the dynamical and thermal stabilization of a cold dense neutral cloud in a hot, thin, and magnetized ambient halo plasma is addressed. The results of …
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