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 21 for “"Stability boundaries"”.
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Evaluation of Stability Boundaries in Power Systems
… to determine whether the system is nearing instability. This dissertation demonstrates several ways in which the power system stability boundary can be calculated. The power system movements evaluated here address the effects of inter-area oscillations on the system which occur in the seconds …
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Analytic calculations of MHD equilibria and of MHD stability boundaries in fusion plasmas
… compared with the ideal MHD energy principle. Stability comparison theorems are presented. The main conclusion can be summarized in two points. (1) In systems with ergodic magnetic field lines, ideal MHD accurately predicts marginal stability, even in fusion grade plasmas. (2) In closed field …
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Stability of a reticulated dome under multiple independent loads
… primary purpose of this thesis is to investigate stability boundaries, or load interaction curves, of a reticulated dome. An elastic, geometrically nonlinear model with 21 degrees of freedom is considered. The nonlinear response of the model to imposed loads is determined using two separate …
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Static and dynamic stability analysis of a truss model
… study is to investigate the static and dynamic stability of an elastic truss model. The truss model· is subjected, separately, to static loads, dynamic step loads, and dynamic impulse loads. For each loading, the results are presented in the form of stability boundaries and displacement …
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An arbitrarily shaped satellite in the restricted problem of three bodies
… are derived. The phenomenon of resonance and stability are discussed. Stability boundaries for such a space station are established. Initial conditions and pointing errors are analyzed.
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Analytical investigation of the tilt rotor whirl instability
… a generalized analytical study of the whirl instability of a rotating propeller or rotor system. The mathematical model consists of rigid members with three degrees-of-freedom at the wing root and the wing-drive-shaft joints. In addition, each blade has lagging and flapping freedom. Two …
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Theoretical foundations for finite-time transient stability and sensitivity analysis of power systems
<p>Transient stability and sensitivity analysis of power systems are problems of enormous academic and practical interest. These classical problems have received renewed interest, because of the advancement in sensor technology in the form of phasor measurement units (PMUs). The advancement in …
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Determination of interaction curves for the stability of a three degree of freedom, shallow arch model under multiple dynamic loads
The primary purpose of this study is to determine stability boundaries (interaction curves) for a three degree of freedom, shallow arch model under multiple dynamic loads. The model consists of four rigid bars connected by frictionless pins, with rotational springs and dashpots at the three …
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Machine tool chatter suppression using spindle speed variation
… part of the thesis deals with the dynamics and stability of nonlinear delay gyroscopic systems with periodically varying delay. The aim is to demonstrate that greater depths of cut may be achieved in a boring process (2 DOF) when the speed of the spindle is modulated sinusoidally instead of …
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Resilience Engineering via Bifurcation and Ecological Network Analysis: Demonstrated in an Electric Power Case Study
… to identify critical operating thresholds and stability boundaries. ENA, originating from systems ecology, is utilized to analyze the network structure and flow characteristics, potentially revealing topological vulnerabilities and strengths related to resilience. The primary research goal is …
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Fast prediction of transonic aeroelasticity using computational fluid dynamics
… for the augmented solve of the onset point of instability - the flutter point. This method contains all the fidelity of the original aeroelastic equations at much lower cost as the stability calculation has been reduced from multiple unsteady computations to a single steady state one. Once the …
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Stability of reticulated domes under multiple static and dynamic loads
… of this dissertation is to investigate the stability of reticulated domes under multiple static and dynamic loads. Two elastic geometrically nonlinear structural models of a reticulated dome with 21 and 39 degrees of freedom are considered. The nonlinear response of the system to static …
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Design, analysis and evaluation of sigma-delta based beamformers for medical ultrasound imaging applications
… intravascular imaging systems. In addition, the stability boundaries of higher-order High-Pass (HP) and Band-Pass (BP) Σ−Δ modulators for single- and dual- sinusoidal inputs are determined using quasi-linear modeling together with the describing-function method, to more accurately model the …
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Flow Between a Cylinder and a Rotating Coaxial Cylinder, Axisymmetric Shaft With Axially-Periodic Radius Variation, or Screw
… shaft is a circular cylinder, complete linear stability boundaries are determined for a wide range of parameters. The analysis accounts for arbitrary infinitesimal disturbances over the entire range of Reynolds numbers (Re) for which SPF is stable. For flows satisfying the zero-Re Rayleigh …
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Nonlinear flutter of composite shear-deformable panels in a high-supersonic flow
… and in-plane edge restraints on the stability boundaries are also studied. It is observed that the classical plate theory over-predicts the instability loads, and only the shear deformation theory correctly models the panel which is flexible in transverse shear. When aerodynamic …
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The Dynamics of Natural Enemy Resistance in Aphid Populations
… parasitoid population dynamics were explored and stability boundaries between stable and oscillating populations identified. The degree of suppression of host populations by parasitoids was determined. Contrary to conclusions reported in the published literature, endosymbiont-infected and …
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Dynamics and Stability of Parametrically Excited Gyroscopic Systems
We study the reduction, dynamics and stability of two-degree-of-freedom mechanical systems. We are particularly interested in understanding energy transfer between modes in such systems. The first part of this research is concerned with the stochastic stability of a two-degree-of-freedom linear …
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Transient behavior of curved structures
… time records of the response after a physical instability event. The performance of several time-stepping schemes is analyzed by identifying the important features that affect the numerical accuracy and robustness. We also identify the region where the schemes are stable for such simulations. The …
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Robustification in Repetitive and Iterative Learning Control
… of in a model, as time goes to infinity. The stability robustness to model uncertainty however remains a fundamental topic as it determines the successful implementation of RC and ILC on any real-world system whose model dynamics cannot normally be determined precisely over all frequencies up …
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Mathematical models of combustion at high pressure
… structure of planar flames, as well as their stability. Stability boundaries are identified that mark the transition from planar to either steady, spatially periodic structures, or time-dependent modes of propagation. The combined effects of the Soret diffusion coefficient and Lewis number are …
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