Acoustics, Dynamics, and Controls Commons^™

A Polar Turbulence Invariant Map With Applicability To Realisable Machine Learning Turbulence Models, James G. Wnek, Christopher Schrock, Eric M. Wolf, Mitch Wolff

Mechanical and Materials Engineering Faculty Publications

Invariant maps are a useful tool for turbulence modelling, and the rapid growth of machine learning-based turbulence modelling research has led to renewed interest in them. They allow different turbulent states to be visualised in an interpretable manner and provide a mathematical framework to analyse or enforce realisability. Current invariant maps, however, are limited in machine learning models by the need for costly coordinate transformations and eigendecomposition at each point in the flow field. This paper introduces a new polar invariant map based on an angle that parametrises the relationship of the principal anisotropic stresses, and a scalar that describes …

Nonlinear Hydrodynamic Modeling And Control Of Wave Energy Converters, Tania Demonte Gonzalez

Dissertations, Master's Theses and Master's Reports

The growing urgency to transition towards carbon-neutral energy sources has sparked significant interest in diversifying energy portfolios by incorporating renewable energies, including the untapped potential of wave energy. This dissertation sets its objectives in advancing wave energy converter (WEC) technologies by focusing on developing and validating a nonlinear modeling technique and designing control strategies to maximize energy extraction and enhance WEC efficiency. At the heart of this research is the derivation and validation of an algebraic nonlinear Froude-Krylov forces model. Building on this foundational model, a robust nonlinear sliding mode controller and a nonlinear model predictive controller are designed to …

Modeling, Simulation And Control Of Microrobots For The Microfactory., Zhong Yang

Electronic Theses and Dissertations

Future assembly technologies will involve higher levels of automation in order to satisfy increased microscale or nanoscale precision requirements. Traditionally, assembly using a top-down robotic approach has been well-studied and applied to the microelectronics and MEMS industries, but less so in nanotechnology. With the boom of nanotechnology since the 1990s, newly designed products with new materials, coatings, and nanoparticles are gradually entering everyone’s lives, while the industry has grown into a billion-dollar volume worldwide. Traditionally, nanotechnology products are assembled using bottom-up methods, such as self-assembly, rather than top-down robotic assembly. This is due to considerations of volume handling of large …

Understanding The Nonlinear Dynamics Governing Vertical-Lift Vehicles With Variable-Speed, Fixed Rotors, Stephanie Vavra, Micah Busboom, Aleea Stanford, Keegan Moore

UNL Student Research Days Posters, Undergraduate

Problem: Traffic significantly limits travel in urban areas. • The NASA Urban Air Mobility Project is developing an air taxi as an alternative mean of transportation (Fig. 1).

Challenge: Operating rotors at different frequencies may cause the cabin to vibrate at high amplitudes. Such effects are currently unknown.

Objective: Understand the effect of variable speed rotors on passenger comfort.

From the reduced-order modeling simulations, it can be assumed that counteracting the rotor speed in-balances can reduce the displacement and vibrations experienced at the center of the wing. In other words, should a rotor not maintain its optimal operation speed, reducing …

Nonlinear Model Development And Validation For Ball And Plate Control System, Zachary Richter

Master's Theses

Ball and plate balancing control systems are commonly studied due to the complex dynamics associated with the instability of the system in open-loop. For simplicity, mathematical models describing the ball and plate dynamics are often linearized and the effects of complex motion are assumed to be negligible. These assumptions are rarely backed with evidence or explanations validating the simplified form of the dynamical equations of motion. This thesis focuses on developing a nonlinear model that more accurately defines the dynamics of the system, in order to quantify the error of linear and nonlinear models when compared to a Simscape physical …

Analysis And Control Of Fiber-Reinforced Elastomeric Enclosures (Frees), Soheil Habibian

Master’s Theses

While rigid robots are extensively used in various applications, they are limited in the tasks they can perform and can be unsafe in close human-robot interactions. Soft robots on the other hand surpass the capabilities of rigid robots in several ways, such as compatibility with the work environments, degrees of freedom, manufacturing costs, and safe interactions with the environment. This thesis studies the behavior of Fiber-Reinforced Elastomeric Enclosures (FREEs) as a particular type of soft pneumatic actuator that can be used in soft manipulators. A dynamic lumped-parameter model is created to simulate the motion of a single FREE under various …

A Perceptual Comparison Of “Black Box” Modeling Algorithms For Nonlinear Audio Systems, Paul G. Mayo

Student Theses

Nonlinear systems identification is a widespread topic of interest, particularly within the audio industry, as these techniques are employed to synthesize black box models of nonlinear audio effects. Given the myriad approaches to black box modeling, questions arise as to whether an “optimal” approach exists, or one that achieves valid subjective results as a model with minimal computational expense. This thesis uses ABX listening tests to compare black box models of three hardware audio effects using two popular nonlinear implementations, along with two proposed modified implementations. Models were constructed in the Hammerstein form using sine sweeps and a novel measurement …

Reduced Order Modeling For Virtual Building Commissioning, Sean Rosin

Boise State University Theses and Dissertations

Model order reduction can help reduce the time and monetary constraints associated with building commissioning and significantly decrease overall building energy consumption through virtual commissioning. This research aimed to determine the effectiveness of using reduced order models to simulate the overall building energy consumption, and to estimate the energy savings from control-based commissioning recommendations.

A case study building was modeled using a ‘Lumped RC’ thermal model with three thermal resistances and capacitances (3R3C) for the building interior and a 2R1C model describing the building foundation. Due to energy consumption being dependent on building systems, this model was coupled with a …