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 114 for “"Spirals"”.
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On a driving mechanism for galactic spirals.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mathematics, 1973
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Shock formation and star formation in galactic spirals,
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1969.
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Shear strength and behavior of circular concrete members reinforced with FRP bars and spirals
Les éléments circulaires en béton armé sont largement utilisés dans les structures en génie civil, comme par exemple, les pieux et les piles de pont. Également, ils sont très utilisés dans les systèmes de pieux battus dans des environnements agressifs et marines. Ces éléments sont habituellement …
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Seismic retrofit and repair of reinforced concrete bridge columns using shape memory alloy spirals
… on examining the use of shape memory alloy (SMA) spirals in the seismic retrofitting and repair of reinforced concrete (RC) bridge columns. The thermally triggered recovery stress of prestrained SMA spirals is utilized to apply large active confinement pressure at the column’s plastic hinge zone …
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Probabilistic seismic demand models of RC bridge columns retrofitted with shape memory alloy spirals
… confinement using shape memory alloy (SMA) spirals can significantly improve their ductility, resulting in enhanced seismic performance. The research work done till date in this area is limited to exploring experimentally the efficacy of this new retrofit technique on a material and …
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Transference of efficacy beliefs and effects of self-efficacy-performance spirals at group and individual levels
… investigate the effects of efficacy-performance spirals at the individual and group levels, as produced by the manipulation of feedback, and (ii) to study the transference of efficacy beliefs (about the self and about the group) to new working groups. Computer-mediated communication will be used …
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Behavior of RC hollow circular columns reinforced with GFRP bars and spirals under concentric and eccentric loads
L’un des problèmes les plus graves auxquels sont confrontées les structures en béton armé d’acier est la détérioration des éléments structuraux causée par l’aggravation des problèmes de corrosion de l’acier, en particulier dans les environnements difficiles tels que les structures marines, les …
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Behavior, strength and flexural stiffness of circular concrete columns reinforced with FRP bars and spirals/hoops under eccentric loading
La détérioration des structures en béton armé avec des barres d’armature d’acier peut être observée quotidiennement dans les régions à climat agressif. Le renforcement interne en polymères renforcés de fibres (PRF) a démontré sa faisabilité grâce à différents éléments structuraux en génie civil. …
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Observed microphysical characteristics and inferred thermodynamic processes contributing to the structure, evolution, and maintenance of nocturnal elevated mesoscale convective systems
… at multiple stages of system development. These spirals sampled MCSs corresponding to various archetypes, including several conforming to the classic leading-line/trailing-stratiform mode, and others conforming to the parallel stratiform, leading stratiform, and nonlinear system modes. In one …
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Spatial and spectral comparisons of soft X-rays from galaxies of different morphological types
… the nature of X-ray emission associated with spirals and that of ellipticals. This thesis compares spectral and spatial information for normal galaxies to that of galaxies experiencing environmental encounters in order to clarify the evolutionary relationship between spirals, mergers and …
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Modeling of Spiral Waves Arising in Atrial Fibrillation
The objective of this study is to model spirals arising in atrial fibrillation. Spiral wave fronts, known to cardiologists as cardiac rotors, are responsible for heart arrhythmias. The modeling of the path of the spiral will ultimately assist in understanding why arrhythmias occur and how to treat …
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Design and Analysis of Star Spiral with Application to Wideband Arrays with Variable Element Sizes
… that uses different sized circular Archimedean spirals for each octave of frequency coverage. A two-octave WAVES array has been presented in the literature, but a gap in the two-octave frequency coverage exists along the principal axes. The star spiral antenna was developed to eliminate the …
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A house, a vineyard
… the principles of Hierarchy, Axis, Passages, and Spirals.
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Development and Resultant Implementation of Custom Software for Analyses of Galactic Neighborhoods
… environments of unbarred spiral galaxies and to spirals for which the presence of a bar cannot be confirmed or rejected. I find that the environments of early-type galaxies are similar to each other; also all types of spirals also share similar environments. This suggests secular evolution is a …
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Design of an Ultra-Wideband Spiral Antenna for Ground-Penetrating Microwave Impulse Radar Applications
… Spiral Antennas” proposes using combination spirals, which combine the performance of multiple simple spiral antennas. This work investigates combination spiral suitability through 3D EM simulations and micro-strip fabrication. Testing results indicate that combination spirals possess …
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Weighing the Milky Way While Exploring Dynamical Disequilibrium
… an ancient perturbation for the origin of phase spirals, and analyzed our fitting residuals in frequency-angle spaces accordingly to measure the perturbation age. We first confined our fitting to the vertical dimension and developed a new form of distribution function (DF). Our potential and DF …
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Experimental testing and constitutive modeling of concrete confined with shape memory alloys
… the idea of using shape memory alloy (SMA) spirals to apply active confinement to concrete prior to loading without the need for mechanical prestressing and some research has been done on this topic in the past few years. Results so far show the promise of this new technique for seismic …
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Design of Multidimensional Large -Tip -Angle Radiofrequency Pulses for Parallel Transmission in Magnetic Resonance Imaging
… trajectories, termed the variable slew-rate spirals, is proposed to locally reduce B 1 amplitude of 2D RF pulses. The peak B1 reduction is achieved by changing the gradient slew-rate profile, and hardware constraints such as gradient amplitude and slew-rate constraints are inherently …
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The morphology and absolute diameters of galaxies
… diameters of galaxies, particularly the spirals. Small, high surface brightness spiral galaxies form an important subgroup; these present a saturated or predominantly saturated image on the SRC IIIa-J Survey. An intercomparison of their appearance on the J-film copies and those of the …
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