Disturbance events occur outside the normal disturbance regime of a system and can cause changes in behavior of some organisms. The 2010 cold event is an example of a disturbance event that influenced the behavior of Common Snook (Centropomus undecimalis). Common snook are euryhaline sportfish native to Florida, Texas, and the Caribbean. Florida is the northern most part of their distribution, based on the 15o C winter isotherm. They move between offshore areas during spawning season and freshwater coastal rivers during non-spawning season. With the use of previously collected acoustic telemetry and biological data this project identifies the impact on population dynamics and movement near the time of the event. The goal is to understand fine scale movements and physiological conditions under normal and abnormal conditions to further inform management of the species. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Modeling, system identification and controller design for a 16’ catamaran is described with the objective of enhanced operation in the presence of environmental disturbances including wind, waves and current. The vehicle is fully-actuated in surge, sway and yaw degrees of freedom. Analytical and experimental system identification is carried out to create a numerical model of the vehicle. A composite system of a Multiinput multi-output Proportional-Derivative (PD) controller and a nonlinear disturbance observer is used for station-keeping and transiting modes of operation. A waypoint transiting algorithm is developed to output heading and cross-track error from vehicle position and waypoints. A control allocation method is designed to lower azimuthing frequency and incorporate angle saturation and rate limits. Validation is achieved with improvement in simulation with the addition of the nonlinear observer. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection