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 24 for “"radius ratio"”.
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Vortex Ring Collision with Free-Slip and No-Slip Wall
… no-slip and free-slip walls for different radius ratio (0.1, 0.2, 0.3, and 0.4). Structural and dynamic information, statistics on energy transfer and vortex stretching obtained using the simulations. Three-dimensional simulations helped to understand the mechanism of the formation of …
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Presnosť určenia parametrov exoplanét z ich tranzitov
… two fundamental parameters-the planet-to-star radius ratio and the mid-transit time. The data for this study was collected as part of an organized observing campaign in collaboration with SPHE ČAS, during which five exoplanets were observed under varying atmospheric and instrumental conditions. …
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Investigation of the GEM MPD thruster using the MACH2 magnetohydrodynamics code
… the performance of the actual thruster. Thruster radius ratios of 3.4 and 5 were examined, and a mass flow rate of 6 g/s was specified for each. In this study, several properties were examined and compared with the experimental GEM thruster. A voltage of 148 V was computed for the GEM thruster …
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Infrared excesses from accretion streams in pre-main-sequence binaries
… hot enough and/or viscous enough (thickness-to-radius ratio c ≥ 0.05, for viscosity parameter alpha > 0.01). We modeled binaries with different mass ratios and eccentricities and calculated the spectral energy distribution of the binary-disk system, for an optically thick disk. We focused on …
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Computational assessment of turbine rim seal system parametric variation on hot gas ingestion and flow pattern
… focused on are purge to main mass flow rate ratio, axial gap to rim radius ratio, radial gap to rim radius ratio, normalized axial position of the blade leading edge, and internal purge cavity radius ratios. The results were used to formulate a non-dimensional sealing parameter, [psi], that …
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Purely ionic and molecular orbital modelings of the bonding in mineral crystal structures
… sphalerite, rocksalt, and CsCl types in an exploration of the reliability of the radius ratio rule. The MEG model predicts the correct cation coordination numbers for 13 of 16 alkali halides, whereas the radius ratio rule predicts the correct coordination numbers in at most 9 of the same 16 …
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An optical/digital incoherent image processing system for an extended depth of field
… by choosing an annular aperture with a proper radius ratio. However, in the process of increasing the depth of focus of the system, this method results in a loss of image contrast. An annular pass filter can be used to restore this loss in contrast. A simple hybrid optical/digital image …
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Internal friction of mixed-alkali silicate glasses
… glasses is more easily correlated with the radius ratio of the two alkali ions present than with the mass ratio. A stress induced alkali ion position interchange is suggested as the probable mechanism responsible for this peak"--Abstract, page ii.
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Design and tests of a six-stage axial-flow compressor having a tip speed of 550 feet per second and a flat operating characteristic at constant speed
… characteristic (constant stagnation-pressure ratio at constant speed over the operating range of the compressor) was designed and tested. The design theory and test results are presented in this thesis. It was designed for a constant power input per pound of flow regardless of mass flow. The …
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A general solution for the thermal stresses and strains in an infinite, hollow, case-bonded rocket grain
… maximum stress and strain appeared at the inner radius of the grain. It was also observed that the stress and strain increased with an increase in the radius ratio "m”. Failure criteria for the grain under consideration were discussed. A method for obtaining the maximum allowable temperature …
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Turbulent fluid flow and heat transfer in annular passages with rough surfaces and moving cores.
… New equations are proposed for predicting the radius of maximum fluid velocity and the effects of core velocity on roughness, in terms of annulus radius ratio, roughness geometry, flow's Reynolds number and core velocity. The study demonstrates the advantages, under certain conditions, of using …
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The construction, development and application of potential simulation models to the filling of carbon nanotubes by molten salts
… molten salts. The resulting structures, usually rationalised in terms of known bulk crystal structures, are shown to be contained within a general set of structures classifi�ed in terms of folded sheets of in�finite squares and hexagons. A flexible model for the carbon nanotube is employed (using …
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Low order models for hybrid gas bearings
… bearing will have a very low length to diameter ratio (O(.1)) and a very large clearance to radius ratio (0(0.01)). As a result, the bearing lies outside the standard operating regime and stable operation is a challenge. The model presented in this paper is able to predict the bearing's behavior …
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Existence and Analysis of a Rotating Stall Inception Continuum & Development of Concept Questions in Fluid Dynamics
… for an isolated rotor, with a high hub to tip radius ratio, using TBLOCK, a Reynolds Averaged Navier Stokes solver. The results show (i) the dependence of stall inception on the compressor axisymmetric pressure rise characteristic and the characterization of mode and spike stall inception as …
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Characterization of syntactic foams and their sandwich composites: modeling and experimental approaches
… four point bending and short beam shear configurations. Syntactic foams are tested in three different specimen sizes and orientations to characterize them as per the recommendations of various ASTM standards. Effect of specimen aspect ratio on the measured mechanical properties can be determined …
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Flow Between a Cylinder and a Rotating Coaxial Cylinder, Axisymmetric Shaft With Axially-Periodic Radius Variation, or Screw
… for Re below a minimum value. For some ratios of the radii and angular velocities, disconnected neutral curves lead to a multi-valued stability boundary. It is also shown that the smallest radius ratio for which annular Poiseuille flow is linearly unstable is about 0.12, below which no …
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Torsion of Elliptical Composite Cylindrical Shells
… cross sections, defined by their aspect ratio, the ratio of minor to major radii, are considered: 1.00 (circular), 0.85, 0.70, and 0.55. Two overall cylinder sizes are studied; a small size with a radius and length for the circular cylinder of 4.28 in. and 12.85 in., respectively, and a …
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Heat transfer in packed beds of crushed rock
… size, particle roughness and particle aspect ratio. In this study, the thermal performance of the packed bed of crushed rocks is evaluated while specifically investigating the influence of the flow direction/ particle orientation through the packed bed. The results are intended to provide …
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Numerical and experimental investigation of the bending response of thin-walled composite cylinders
… a beam in bending. The cylinders have a nominal radius of 6 inches, a length-to-radius ratio of 2 and 5, and a radius-to-thickness ratio of approximately 160. A [±45/0/90]S quasi-isotropic layup and two orthotropic layups, [±45/02]S and [±45/902]s, are studied. A geometrically nonlinear …
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Protein polarization in packed hollow fibre bioreactors
… a porous medium with a uniform initial concentration of protein. A constant lumen flow was established for several days before the cartridge was sacrificed and the axial ECS protein distribution was measured. Since the protein transport and HFBR hydrodynamics were coupled, numerical methods …
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