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 37 for “"Mode transition"”.
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Numerical Simulation of Mode Transition in a Hydrogen-Fueled Scramjet
… (CFD) flow solver was used to simulate dual-mode direct-connect ramjet/scramjet engine flowpath tests conducted in the University of Virginia (UVa) Supersonic Combustion Facility (SCF). The objective was to develop a computational capability within Wind-US to aid current hypersonic research …
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Measurement of ultrasonic wave mode transition in unidirectional graphite/epoxy composites
The wave propagation mechanism of mode transitions was studied in unidirectional composite materials. Theoretical calculations were compared with experimental measurements. Mode transitions occur when the wave vector orientation is varied in unidirectional samples of T300/5208 graphite/epoxy …
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The L- to H-mode transition and momentum confinement in Alcator C-Mod plasmas
… plasma column was measured during the L- to H-mode transition. Momentum transport was measured in both Ohmic and ICRF-heated discharges, which produced EDA and ELM-free H-modes. The momentum transport was modeled by a simplified diffusion model, in which momentum diffusivity was substantially …
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Multiple model estimation for linear stochastic hybrid systems with non-homogeneous transition probabilities
… surrounding estimation, filtering, and multiple model based systems is presented. More specifically, the often made assumption of a constant time-invariant mode transition probability matrix is relaxed. Recent work done in the area of non-Markov jump stochastic hybrid systems is explored, …
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Lunar landing : dynamic operator interaction with multi-modal automation systems
The ability of operators to "gracefully transition" (maintaining control and awareness of the system without excessive workload or decrements in flight performance) between levels of automation (LOA) in several case studies and in a simulated lunar landing was investigated in anticipation of future …
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Characterization of a Low Current LaB6 Heaterless Hollow Cathode with Krypton Propellant
… diagnostic tool used experimentally. A plasma model is used to infer plasma parameters in the cathode emitter region. The cathode characterization results are consistent with those obtained during previous investigations of 1 A-class LaB6 hollow cathode with krypton. A peak-to-peak anode …
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HIGH-FIDELITY MODELING AND PHYSICS OF BIO-INSPIRED MORPHING AND FLAPPING WINGS
… three-dimensional flexible multibody aeroelastic modeling framework and the exploration of the role of flexibility in coupled dynamics. To predict the fully-coupled fluid-flexible multibody structure system, a partitioned body-fitted formulation based on the coupling of an incompressible unsteady …
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Study of H-mode access conditions on the Alcator C-Mod Tokamak
… is injected, tokamak plasma will make an abrupt transition into a state with improved confinement, known as the high-confinement mode, or H-mode. Given the greatly enhanced fusion yield, H-mode is foreseen as the baseline scenario for the future plasma operation of the International Thermonuclear …
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An investigation of the effects of curvatures on natural vibration characteristics of curved beams and plates
… through the numerical method. In the numerical model, the curved beam or plate is easily simulated by assembled elements. Although the approximate solution can be obtained, numerical results are inadequate to demonstrate the effect of the curvature on the whole system. In order to reveal such …
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Design and Analysis of High-Stability THz Molecular Clock System
… stability performance by using a rotational-mode transition of gaseous carbonyl sulfide (¹⁶O¹²C³²S). Its low-cost implementation and robustness against external electrical/magnetic fields make a CSMC an attractive candidate for a high-stability clock. However, even though an invariant OCS …
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A combined cycle approach to dual-mode scramjet design and analysis
… processes in these flows, they elude adequate modeling due to the complexities and coupling of the phenomena present and the difficulty in reproducing relevant flows in current ground test facilities. Flight testing is a crucial phase in the comprehensive study of hypersonic and …
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Frame synchronisation methods for digital satellite system
… prototype frame synchroniser, such as various mode transition strategies, automatic polarity correction, bit slippage tolerance up to ±2 bits and a bit error rate (BER) tolerance up to 0.208, were demonstrated via a range of tests, which are described in this thesis.
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Managing transient behaviors of a dual mode spark ignition-- controlled auto ignition engine with a variable valve timing system
… and several important phenomena in CAI mode were investigated. Second, the issues encountered during mode transition between SI and CAI regime were considered. Despite wide-open-throttle operation, pumping loss in CAI mode was not negligible. A major source of pumping loss in CAI mode …
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Experimental study of turbulent heat transport in Alcator C-Mod
… new information about the Ohmic confinement transition, from the linear to the saturated confinement regime with the increase in average density. It was found that Te fluctuations near the edge (r/a0~.85) tend to decrease across the Ohmic confinement transition. Although the Ohmic confinement …
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Free Vibration of Bi-directional Functionally Graded Material Circular Beams using Shear Deformation Theory employing Logarithmic Function of Radius
… provides frequencies and the corresponding mode shapes. Results are presented for different spatial variations of the material properties, boundary conditions, and the aspect ratio. It is found that the radial and the circumferential gradation of material properties maintains their natural …
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Analysis of the Power Conditioning System for a Superconducting Magnetic Energy Storage Unit
… was developed to coordinate charge/discharge transitions. The system controller integrated the chopper and VSC controller, configured applicable loads, and dictated sequencing of events during mode transitions. Initial tests with a SMES coil resulted in problems during mode transitions. These …
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Stress corrosion cracking and corrosion of carbon steel in simulated fuel-grade ethanol
… crack initiation/propagation and the corrosion mode transition. Inclusions in the steel can increase local plastic strain and act as crack initiation sites. Secondly, the anodic behavior of carbon steel electrode was investigated in detail under different ethanol chemistry conditions. General …
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Modeling dynamic ruptures with high resolution fault zone physics
… the earthquake source processes, computational modeling of these processes continue to be a major challenge. In this research, we address this challenge by developing new models that shed novel insights into the different faces of complexity of the earthquake source. We first introduce the …
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Energy-efficient Wireless Sensor Network MAC Protocol
… nodes into one of the available energy-saving modes based upon the sleep period duration and the current state of the radio. This research investigates energy-efficient medium access control (MAC) protocols designed to extend both the lifetime and range of wireless sensor networks. These …
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