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 24 for “"modeling uncertainties"”.
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An Investigation of the Behavior of Structural Systems with Modeling Uncertainties
… in structural analysis results due to modeling techniques has not been considered. This work investigates the uncertainty associated with modeling geometric nonlinearities and Rayleigh damping models on the response of planar frames at multiple ground motion intensity levels. First, an …
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Quantification of Spalart-Allmaras Turbulence Modeling Uncertainties for Hypersonic Flows Utilizing Output-Based Grid Adaptation
In this thesis, uncertainty in the Spalart-Allmaras (SA) turbulence model with the compressible Reynolds-averaged Navier-Stokes (RANS) equations is quantified for steady non-reacting hypersonic flows using a coarse-grained uncertainty metric. Output-based adaptation is utilized to guarantee …
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Robust optimization for network-based resource allocation problems under uncertainty
… to protect against future uncertainty. By modeling uncertainties in data corresponding to service times, resource availability, supplies and demands, we can generate solutions that are more robust operationally, that is, more likely to be executed or easier to repair when disrupted. The …
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Modeling and identification of time-varying systems - A wavelet approach
The present work proposes a methodology for modeling and identification of boundedinput bounded-output (BIBO) time-varying (TV) system impulse responses based on a wavelet approach. This approach permits representation of a time-varying system impulse response in the auxiliary domains, commonly …
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A state-space approach to dynamic tomography
… when faced with inevitable measurement and modeling uncertainties. In addition, the dissertation offers signal processing methods that scale to meet the computational demands of high-dimensional state estimation problems such as dynamic tomography. Major contributions include a rigorous …
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Uncertainty in marine structural strength with application to compressive failure of longitudinally stiffened panels
… and scatter in the prediction of strength (modeling uncertainty). The vagueness component is briefly discussed. A methodology for quantifying modeling and random uncertainty is presented for structural failure modes with a well defined limit state. A methodology is also presented for …
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A Robotic Head Stabilization Device for Post-Trauma Transport
… in rejecting perturbations and handling modeling uncertainties. The performance the proposed LADRC control scheme was compared with PID in simulation and the results are presented. Finally, a prototype of the device was designed and built to validate the functionality of the subsystem, …
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Neural network applications in the control of power electronic converters
… control systems where they are to deal with any modeling uncertainties that may exist. This thesis proposes the Neural Network controller as a viable alternative to the conventional and widely used PI regulator for the regulation of Power Electronic converters. Neural Networks may be used to both …
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Analysis of Model-Free Control of Wind Farms Using Large-Eddy Simulations
… but learns on-line the system dynamics, avoiding modeling uncertainties. The control strategies are based on extremum-seeking control (ESC), a real-time gradient-based optimization algorithm. Either the turbine generator torque or the rotor yaw angle is used as the control parameter tuned by ESC …
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Constrained Control of Complex Helicopter Models
… and blade flapping are also modeled. The modeling process is motivated by the desire to build control oriented, physics based models that directly result in ordinary differential equations (ODE) models which are sufficiently rich in dynamics information. A physics based model …
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Control of flexible-link manipulators using nonlinear H(infinity) techniques
… system is required to be robust with respect to modeling uncertainties. Robust control strives to characterize the uncertainty in the model of the plant and to evaluate the degrees of freedom left to achieve the control task within specified bounds. This dissertation is concerned with the control …
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Novel probabilistic and distributed algorithms for guidance, control, and nonlinear estimation of large-scale multi-agent systems
… in size to the spacecraft and has significant modeling uncertainties, conventional nonlinear control laws that use exact feed-forward cancellation are not suitable because they exhibit a large resultant disturbance torque. The proposed nonlinear tracking control law guarantees global …
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Control of large-scale structures with large uncertainties
… and active damping systems, such as large modeling uncertainties that are inherent to large-scale structures, limited state measurements, lack of mechanically reliable control devices, large power requirements, and the need for robust controllers. In order to enhance acceptability of …
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Vision Based Guidance and Flight Control in Problems of Aerial Tracking
… with a neural network for approximation of modeling uncertainties and atmospheric turbulence resulting from the closed-coupled flight of two aerial vehicles.
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Assessing environmental benefits and economic costs of aviation environmental policy measures
… impact assessment and quantification of modeling uncertainties can enable a more comprehensive evaluation of aviation environmental policy measures. A comparison is presented between the conventional cost-effectiveness analysis and an illustrative cost-benefit analysis focused on …
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Impacts of model-data uncertainties on biogeophysical-biogeochemical interactions in a land surface model (with an emphasis on the northern high-latitude regions)
… investigated the impacts of current model-data uncertainties on biogeophysical-biogeochemical interactions in a terrestrial modeling framework. To achieve this objective, I applied a land surface model, specifically the Integrated Science Assessment Model (ISAM), at spatial scales ranging from …
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Experimental comparison of probabilistic methods and fuzzy sets for designing under uncertainty
… problems. An alternative approach for modeling uncertainties is fuzzy sets. Fuzzy sets usually require much less information than probabilistic methods and they rely on expert opinion. In principle, probability theory should work better in problems involving only random uncertainties, …
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A Low-Cost Unmanned Aerial Vehicle Research Platform: Development, Modeling and Advanced Control Implementation
This dissertation describes the development and modeling of a low-cost, open source, and reliable small fixed-wing unmanned aerial vehicle (UAV) for advanced control implementation. The platform is mostly constructed of low-cost commercial off-the-shelf (COTS) components. The only non-COTS …
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Sliding Mode Controller Design for ABS System
… slip. The system shows the nonlinearities and uncertainties. Hence, a nonlinear control strategy based on sliding mode, which is a standard approach to tackle the parametric and modeling uncertainties of a nonlinear system, is chosen for slip control. Due to its robustness properties, the …
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A Computational and Experimental Study on the Electrical and Thermal Properties of Hybrid Nanocomposites based on Carbon Nanotubes and Graphite Nanoplatelets
… experimental study was utilized to reduce the modeling uncertainties and the computational predictions of the proposed models were compared with the experimental measurements. Acceptable agreements between the model predictions and experimental data were observed and explained in light of the …
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