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.
Results
Showing 1 to 20 of 50 for “"global stability"”.
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Global stability and control of swirling jets and flames
… hydrodynamic oscillations, also known as global hydrodynamic instability. Direct numerical simulation (DNS) of the Navier--Stokes equations in the low Mach number limit is used to obtain a steady base flow, and the most unstable direct and adjoint global modes. These are combined, using a …
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A numerical investigation of the global stability of ship roll: invariant manifolds, Melnikov's method, and transient basins
A parametrically forced, single-degree-of-freedom equation modelling ship roll is investigated through the numerical study of invariant manifolds, Melnikov's method, and transient basins. The calculation of the manifolds is facilitated through the development of a sophisticated algorithm for …
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Local and Global Stability and Dynamics of a Class of Nonlinear Time-Delayed One-Degree-of-Freedom Systems
We investigate the dynamics and stability of nonlinear time-delayed one-degree-of-freedom systems possessing quadratic and cubic nonlinearities and subjected to external and parametric disturbances. Due to the time-delay terms, the trivial solution of the unforced system undergoes Hopf …
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Policy robustness : robust stability of multiclass queueing networks
… This dissertation focuses on the robust stability of stochastic processing networks. We re-visit the global—relative to control policies—stability of multiclass queueing networks. In these, as is known, it is generally insufficient that the nominal utilization at each server is below …
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Tuberkuliozės matematinis modelis su netiesine gydymo funkcija /
… medical conditions can be poor. The local and global stability of the equilibrium points determine the dynamics of the proposed models. Conditions for the global stability of the disease free equilibrium are given. It plays an important role in determining if an infection can be eradicated. The …
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Attitude control on manifolds via optimization and contractions with automatic gain tuning
… prevent the controllers from achieving global stability and worse they may cause real physical harm due to unexpected large motions. More recent works have achieved global stability and avoided these system failures by working directly on the configuration manifold, but these approaches …
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Lyapunovfunctions in epidemiological modeling
… functions in general, and their usage in global stability analysis. Lyapunov’s “direct method” is used to analyse the stability of the disease-free equilibrium. Moreover, a matrix-theoretic method is critically examined for its capability and overall functionality in the construction and …
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Essays on economic theory
… spaces, we show that our key condition, called "global stability under uncertainty," implies a variety of results to the effect that the impact of higher-order uncertainty is small. Our central result states that, under global stability, the maximum change in equilibrium strategies due to changes …
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Adaptive control of hypersonic vehicles in presence of actuation uncertainties
… new class of adaptive controllers that guarantee global stability in presence of actuation uncertainties. Actuation uncertainties culminate to linear plants with a partially known input matrix B. Currently available multivariable adaptive controllers yield global stability only when the input …
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A Three Dimensional Model of Virus Dynamics in HIV Patients
… point in the interior of Γ.</p> <p>The local and global stability of each equilibrium point is then studied. If N < N<sub>c</sub>, the local stability of the uninfected state is confirmed by showing the eigenvalues of the Jacobian matrix have negative real parts. A Lyapunov function is found to …
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Mathematical models in evolutionary dynamics
… the former where we are able to prove numerous global stability results.
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Adaptive control of nonlinear systems
… on the nonlinearities in order to guarantee global stability. Such constraints bypass the true nonlinear problem and exclude many practically important systems. Furthermore, most existing results are based on the often unrealistic assumption of full-state feedback.
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Calibrating the LaModel Program for Shallow Cover Multiple-Seam Mines
… of 47 deep-cover case histories, where a stability factor (SF) of 1.40 or above showed a 90% chance of success. During the development of the deep-cover calibration method for LaModel 3.0, there was nothing fundamental in the derivation that limited the method to only deep-cover mines; …
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Forecasting Stability Levels for the Countries of the Former Soviet Union
… reliable forecasts of country, regional, and global stability or instability. Such forecasts require a methodology for identifying and analyzing factors that contribute to stability. The anticipation of this stability level can facilitate crisis warning and diplomatic strategies for various …
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Decentralized Coordinated Attitude Control of a Formation of Spacecraft
… behavior-based control is developed. The global stability of the controller is proven using Lyaponuv stability theory. Convergence of the attitude controller is proven through the use of an invariance argument. The attitude controller's stability and convergence characteristics are …
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Sensitivity methods and slow adaptation
… imposes, a common assumption used to prove global stability requires the regressor to be Persistently Exciting (PE). This PE requirement has been tied to the spectral content of the system input, and is directly proportional to the number of parameters adjusted. Often this imposes …
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Analysis and Simulation for Homogeneous and Heterogeneous SIR Models
… concerning effects of the generalization on the global disease dynamics. The spatial heterogeneity of the metapopulation with nonrandom directed movement between populations is incorporated into a heterogeneous SIR model with nonlinear incidence. The analysis of the combined effects of the …
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A cholera model linking between-host, within-host and environmental disease dynamics
… the conditions needed to achieve local and global stability in each system. Finally, we combine the three smaller models together and discuss the existence and uniqueness of a DFE and EE for the full system.
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Nonlinear and non-modal stability of structures evolving in shear flows
This thesis explores a range of stability techniques applied to fluid structures that develop in various constant density flows. In particular, the stability of nonlinear structures which develop in rotating plane Couette flow is analyzed using Floquet theory, which allows the global stability of …
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Multi-scale and multi-group modeling techniques applied to Cholera and COVID-19
… The conditions needed to achieve local and global stability in each system are reviewed, and numerical simulations are presented to supplement these mathematical results.
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