Physics Commons^™

Transformation Of Nonlinear Waves In The Presence Of Wind, Current, And Vegetation, Haifei Chen

Electronic Theses and Dissertations

Accurate prediction of extreme wave events is crucial for the safe maritime activities and offshore operations. Improved knowledge of wave dissipation mechanisms due to breaking and vegetation leads to accurate wave forecast, protecting life and property along the coast. The scope of the thesis is to examine the wave transformations in the presence of wind, current, and vegetation, using a two-phase flow solver based on the open-source platform OpenFOAM. The Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with a Volume of Fluid (VOF) surface capturing scheme and a turbulence closure model. This RANS-VOF model is adapted to develop a numerical wind-wave-current …

Integrated Environment And Proximity Sensing For Uav Applications, Shawn S. Brackett

Electronic Theses and Dissertations

As Unmanned Aerial Vehicle (UAV), or “drone” applications expand, new methods for sensing, navigating and avoiding obstacles need to be developed. The project applies an Extended Kalman Filter (EKF) to a simulated quadcopter vehicle though Matlab in order to estimate not only the vehicle state but the world state around the vehicle. The EKF integrates multiple sensor readings from range sensors, IMU sensors, and radiation sensors and combines this information to optimize state estimates. The result is an estimated world map to be used in vehicle navigation and obstacle avoidance.

The simulation handles the physics behind the vehicle flight. As …

Using Hydroacoustics To Investigate Biological Responses In Fish Abundance To Restoration Efforts In The Penobscot River, Maine, Constantin C. Scherelis

Electronic Theses and Dissertations

Spatiotemporal advantages linked to hydroacoustic sampling techniques have caused a surge in the use of these techniques for fisheries monitoring studies applied over long periods of time in marine systems. Dynamic physical conditions such as tidal height, boat traffic, floating debris, and suspended particle concentrations result in unwanted noise signatures that vary in intensity and location within a hydroacoustic beam over time and can be mixed with the acoustic returns from intended targets (e.g., fish). Typical processing filters applied over long term datasets to minimize noise and maximize signals do not address spatiotemporal fluctuations of noise in dynamic systems. We …

Basic Vision Research With Clinical Applications And Science Education Assessments, Andrew Wilson

Electronic Theses and Dissertations

Visual Acuity (VA) examinations are one of the most commonly conducted medical assessment throughout the world. Recent advances in computer technology allows for new forms of visual assessment to be conducted. In Part I of this thesis I demonstrate the capability of an automated computer program named VISION to assess human visual acuities. Different color combinations of an object against a background emitted from a computer screen are used to examine a variety of human color vision acuities. Results indicated a large difference in acuity scores between human subjects tested with these different color combinations. A single human subject exhibits …

A Study In Cross-Beam Polarization Fluorescence Photoactivation Localization Microscopy On Dendra2-Hemagluttinin In Fixed Nih3t3 Cells, Matthew M. Valles

Electronic Theses and Dissertations

Fluorescence microscopy is popular for its noninvasive properties and its use in imaging multiple species, simultaneously. Furthermore, superresolution fluorescence microscopy (SRFLM) utilizes photoswitchable proteins to improve the lateral resolution of conventional fluorescence microscopy by an order of magnitude. There is little work conducted on the study of excitation laser polarizations and their effect on the number of localizations as well as the brightness of molecules. This thesis attempts to study the effect of excitation wavelength polarization on the number of localizations and the brightness of molecules by comparing two orientations of circularly-polarized, excitation lasers. The first type of orientation involves …

Investigating Student Learning Of Analog Electronics, Kevin L. Van De Bogart

Electronic Theses and Dissertations

Instruction in analog electronics is an integral component of many physics and engineering programs, and is typically covered in courses beyond the first year. While extensive research has been conducted on student understanding of introductory electric circuits, to date there has been relatively little research on student learning of analog electronics in either physics or engineering courses. Given the significant overlap in content of courses offered in both disciplines, this study seeks to strengthen the research base on the learning and teaching of electric circuits and analog electronics via a single, coherent investigation spanning both physics and engineering courses.

This …