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 35 for “"high-fidelity model"”.
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Low-Thrust Optimal Escape Trajectories from Lagrangian Points and Quasi-Periodic Orbits in a High-Fidelity Model
L'abstract è presente nell'allegato / the abstract is in the attachment
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Surrogate-based optimization using multifidelity models with variable parameterization
Engineers are increasingly using high-fidelity models for numerical optimization. However, the computational cost of these models, combined with the large number of objective function and constraint evaluations required by optimization methods, can render such optimization computationally …
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Mu-synthesis controller design for temperature control of a solar steam gasifier with uncertainty modeling and robust analysis
… lignite and oxygen fed into the reactor core. A high fidelity model developed in previous work was utilized to create a linear, time-invariant model for controller synthesis. Multiplicative uncertainty was used to create an uncertainty model to quantify and account for the dissimilarities between …
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Multidelity approaches for design under uncertainty
… uncertainties as random inputs to the numerical model of the system and investigate the probabilistic behaviour of the model outputs. However, performing optimization in this setting can be computationally expensive, requiring many evaluations of the numerical model to compute the statistics of …
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Online Estimation of Unknown Parameters for Flexible Spacecraft
<p>Attitude controls methods of highly flexible spacecraft have seen increased interest over the last decades thanks to the technological development of flexible solar panels and deploy-ables, which improves the capabilities of small satellites. However, a high-fidelity model of the flexible mode …
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Model adaptivity for goal-oriented inference
… physical systems are represented by mathematical models, characterized by a set of parameters. The inverse problem arises when the parameters are unknown and one tries to infer these parameters based on observations. Solving the inverse problem can require many model simulations, which may be …
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A methodology for non-Intrusive projection-based model reduction of expensive black-box PDE-based systems and application in the many-query context
The projection-based reduced order modeling, typically requires access to the discrete form of governing equations of the high-fidelity model. The projection is commonly done on a subspace determined via POD. However when commercial codes are used as the high-fidelity model, such an approach is not …
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Autonomous Autorotation of a Tilt-Rotor Aircraft Using Model Predictive Control
… total power failure. With low inertia rotors and high disk loading of tilt rotor vehicles, this already difficult task becomes significantly more challenging. In this work, a model predictive controller is developed to autonomously maneuver and land a tilt rotor given complete power loss. A high …
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On-Board Artificial Intelligence for Failure Detection and Safe Trajectory Generation
… generation and modification, as well as high-performance trajectory tracking control laws have been an essential focus of researchers given that integration into the National Air Space (NAS) is becoming a primary need. However, the operational safety of these systems can be easily …
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Modeling and Simulation of a Multi-Unit Tracked Vehicle
… in underground mining applications due to its high mobility and payload capacity on rugged and soft terrain. To automate such a system, a high fidelity model of a tracked vehicle is essential in designing a controller for each tracked vehicle in the system, and a system model is required to …
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Adaptive Torque Control of a Novel 3D-Printed Humanoid Leg
… and cancel out nonlinearities, for which a high-fidelity model of the robot is required. In the case of a 3D-printed robot, components cannot be easily modeled due non-uniform densities, inconsistencies among the 3D printers used in manufacturing, and the use of different plastics with …
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Adaptive Control for Spacecraft with Flexible Appendages with Unknown Parameters
… in control design due to the uncertain dynamical model and the underactuated nature of these systems. Adaptive and robust controllers are the common choice for these systems to either meet operational requirements like attitude pointing or to suppress vibrations. However, these controllers add …
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Modeling Energy Harvesting From Membrane Vibrations using Multi-physics Modeling
… is a good example). Coming up with an efficient, high-fidelity model of these systems allows for design optimization without the extensive use of experimental testing, as well as a deeper understanding of the physics involved. These are the twin goals of this research. This work describes a …
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Development of a Method for Analysis and Incorporation of Rotorcraft Fluctuation in Synthesized Flyover Noise
… through an empirical approach, yields a high fidelity signal, as long as both unmodulated and modulated components are present. In order to extend these signals indefinitely, models for the amplitude and phase modulation must be developed. A band-limited random process will be explored …
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Re-Envisioning Electric Railway Power Systems in Dense Urban Regions
… subway systems in the world. A state-of-the-art high-fidelity model has been developed for NYC’s subway system and simulated under various design and operational scenarios to evaluate the techno-financial feasibility of solar integration, wayside energy storage deployment, and electric vehicle …
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Variations on bayesian optimization applied to numerical flow simulations
… such as including gradient and/or multi-fidelity information, and it has been extended to multi-objective optimization problems. Despite its recent applications to numerical flow simulations, the efficiency of this method and its variants remains to be characterized in typical …
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Physics-based Estimates of Structural Material Quantities for Urban-level Embodied Carbon Assessment in Buildings
… focus on fully detailed material takeoffs from high-resolution Building Information Models (BIM) and are therefore incomplete during conceptual design. Moreover, Urban building energy modeling (UBEM) is a proven technique allowing cities to evaluate technology pathways to achieve their net-zero …
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Nonlinear model reduction for uncertainty quantification in large-scale inverse problems : application to nonlinear convection-diffusion-reaction equation
… applications. In this thesis we present a model reduction methodology that combines efficient representation of the nonlinearities in the governing PDE with an efficient model-constrained, greedy algorithm for sampling the input parameter space. The nonlinearities in the PDE are represented …
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Technical basis for use of a correlated neutron source in the uranium neutron coincidence collar
… (1) discusses the development a benchmarked, high-fidelity model of the UNCL using Monte Carlo N-Particle Extended (MCNPX), version 2.7.4.a; (2) fully characterizes the detection parameters, including the efficiency profile, die-away time, and deadtime parameters; and (3) demonstrates the …
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A certified reduced basis approach to PDE-constrained optimization
… particularly if the parameter dimension is high. It is therefore advantageous to replace expensive high-dimensional PDE solvers (e.g., finite element) with lower-dimension surrogate models. This work builds on the reduced basis (RB) method, a model reduction method that allows efficient and …
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