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 “"stability limit"”.
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Multimode Structure of Resistive Wall Modes near the Ideal Wall Stability Limit
This thesis presents the first systematic study of multimode external kink structure and dynamics in a tokamak using a high-resolution magnetic sensor set. Multimode effects are directly measured, rather than inferred from anomalies in single-mode behavior. In order to accomplish this, an extensive …
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Design and model: Intelligent solid-state current limiter to prevent sympathetic tripping problem on power and energy applications
… that transferring power near the system voltage stability limit is a major cause of the Sympathetic Tripping Problem. Limiting fault current and using synchronous condensers for reactive power support were shown to solve the Sympathetic Tripping Problem.
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Pressure profiles of plasmas confined in the field of a dipole magnet
Understanding the maintenance and stability of plasma pressure confined by a strong magnetic field is a fundamental challenge in both laboratory and space plasma physics. Using magnetic and X-ray measurements on the Levitated Dipole Experiment (LDX), the equilibrium plasma pressure has been …
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Fluid Release During Eclogite Formation, North Qaidam Terrane, Western China
… increase as the P-T path crosses the terminal stability boundary of hydrous minerals. Fluid release rates spike at ~560 kg/m<sup>3</sup>/Myr at the stability limit of amphibole and ~510 kg/m<sup>3</sup>/Myr at the stability limit of lawsonite. Such spikes in fluid release rates are interpreted …
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A Mechanistic Force Model and Stability Analysis for Contour Turning
The stability variations in axial contour turning are investigated via a frequency domain analysis. Three-dimensional stability-limit diagrams, third dimension being the toolpath, are generated for machining a workpiece with concave-convex contours. The reasons for the stability variations along …
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Voltage collapse modes in power networks
Voltage Collapse is instability of a heavily loaded electric power system, which leads to declining voltages and blackout, and it is typically associated with reactive power limitations of the power system. Therefore, knowledge of the critical loading point is vital to ensure a secure mode of …
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Investigation of a prototype industrial gas turbine combustor using alternative gaseous fuels
… aim of the investigation was to find operational limitations for an experimental burner and to supply data for validation of computational fluid dynamics (CFD). Before examination of the actual burner, the laminar flame speed was measured for a range of gases. The measurement technique was based …
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A methodology for centrifugal compressor stability prediction
… stable operation of centrifugal compressors is limited by well-known phenomena, rotating stall and surge. Although the manifestation of the full scale instabilities is similar to the ones observed in axial machines, the stall inception in centrifugal compressors is less well understood. This …
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Hierarchical Fuzzy Control of the UPFC and SVC located in AEP's Inez Area
… Inez network, which was operated close to its stability limits, American Electric Power (AEP) undertook two major developments, one being the installation of a Static Var Compensator (SVC) in November, 1980 and the other one being the installation of the world's first Unified Power Flow …
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An experimental investigation of heat transfer to hydrogen peroxide in microtubes
… microtubes have been performed to define the stability limit and explosion condition associated with 98% hydrogen peroxide thermal decomposition. Conditions such as pressures, temperatures, heat fluxes and length scale found in the engine were replicated. Tests were conducted whereby heat …
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From a thin membrane to an unbounded solid : dynamics and instabilities in radial motion of nonlinearly viscoelastic spheres
… viscoelastic material responses. To explore the stability thresholds of the dynamic motion and to compare them with available formula for the quasi-static limit, the present formulation employs a generalized constitutive relation and accounts for different loading scenarios. Specifically for …
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Rollover prevention and path following of a scaled autonomous vehicle using nonlinear model predictive control
… causes of vehicle accidents is due to vehicle instability phenomena. Vehicle instability can occur due to unexpected road profile changes, during full braking, obstacle avoidance or severe manoeuvring. Three main instability phenomena can be distinguished: the yaw-rate instability, the rollover …
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Experimental characterization of condensation behavior for metastable carbon dioxide
… (subcooled-vapor) properties and related stability limit, known as the Wilson line. While there have been computational studies on metastable CO₂, there is no experimental data in the literature to anchor these results for conditions near the critical point. A laboratory scale blowdown …
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The stability of short-period extrasolar giant planets
… the upper atmosphere is important because the stability of the atmosphere against thermal evaporation is controlled by the conditions in the thermosphere. The thermosphere is heated by the absorption of EUV and X ray (XUV) radiation emitted by the host star. The radiation also ionises the …
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Formation and stability of the solar tachocline in MHD simulations
… the observed thickness of the tachocline. The stability of the solar tachocline is addressed as the next part of the problem. It is shown that the tachocline is stable up to a differential rotation of 52\% in the absence of magnetic fields. This is a new finding as compared to the earlier two …
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Development of a body force model for centrifugal compressors
… methods to determine centrifugal compressor stability limits are based on empirical data and often, experiments. Unsteady full wheel simulations have become feasible due to the increase in computation power but the prediction of the stability limit still remains a challenge. The presented …
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The Application of Improved Numerical Techniques to 1-D Micellar/Polymer Flooding Simulation
… as pos-sible without sacrificing accuracy. The stability limit can also be detected with this method. The method is tested and compared with the fully discrete method in various conditions such as differ-ent phase behavior environments and with or without adsorption. In the application of the …
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Bayesian prediction of functions with applications to manufacturing and marketing
… and marketing. In chapters 2 and 3, stability limit prediction in high speed machining will be considered while in chapter 4 the focus will be on demand curve prediction.
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Ab initio thermodynamics of phase-separating and cation-disordered cathodes for Li-ion batteries
… fleet, the energy density and power density limitations of commercial Li-ion battery cathodes (layered LiMO2) must be overcome. In this thesis, we use ab initio methods to gain critical insights on two important classes of alternative Li-ion battery cathodes, namely high-capacity Li-excess …
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An Investigation of Lean Premixed Hydrogen Combustion in a Gas Turbine Engine
… range of the machine. The strong lean combustion stability of hydrogen-air flames is due primarily to high reaction rates and the associated high turbulent burning velocities. While this is advantageous at low equivalence ratios, it presents a significant danger of flashback — the upstream …
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