Su, Tsung-Chow

FAU's Office of Undergraduate Research and Inquiry hosts an annual symposium where students engaged in undergraduate research may present their findings either through a poster presentation or an oral presentation.

FAU's Office of Undergraduate Research and Inquiry hosts an annual symposium where students engaged in undergraduate research may present their findings either through a poster presentation or an oral presentation.

This dissertation concerns the dynamics and control of an autonomous underwater
vehicle (AUV) which uses internal actuators to stabilize its horizontalplane
motion. The demand for high-performance AUVs are growing in the field of
ocean engineering due to increasing activities in ocean exploration and research.
New generations of AUVs are expected to operate in harsh and complex ocean environments.
We propose a hybrid design of an underwater vehicle which uses internal
actuators instead of control surfaces to steer. When operating at low speeds or in
relatively strong ocean currents, the performances of control surfaces will degrade.
Internal actuators work independent of the relative
ows, thus improving the maneuvering
performance of the vehicle.
We develop the mathematical model which describes the motion of an underwater
vehicle in ocean currents from first principles. The equations of motion of a
body-fluid dynamical system in an ideal fluid are derived using both Newton-Euler
and Lagrangian formulations. The viscous effects of a real fluid are considered separately.
We use a REMUS 100 AUV as the research model, and conduct CFD simulations to compute the viscous hydrodynamic coe cients with ANSYS Fluent. The
simulation results show that the horizontal-plane motion of the vehicle is inherently
unstable. The yaw moment exerted by the relative flow is destabilizing.
The open-loop stabilities of the horizontal-plane motion of the vehicle in
both ideal and real fluid are analyzed. In particular, the effects of a roll torque and
a moving mass on the horizontal-plane motion are studied. The results illustrate
that both the position and number of equilibrium points of the dynamical system
are prone to the magnitude of the roll torque and the lateral position of the moving
mass.
We propose the design of using an internal moving mass to stabilize the
horizontal-plane motion of the REMUS 100 AUV. A linear quadratic regulator
(LQR) is designed to take advantage of both the linear momentum and lateral position
of the internal moving mass to stabilize the heading angle of the vehicle. Alternatively,
we introduce a tunnel thruster to the design, and use backstepping
and Lyapunov redesign techniques to derive a nonlinear feedback control law to
achieve autopilot. The coupling e ects between the closed-loop horizontal-plane
and vertical-plane motions are also analyzed.

As humans explore greater depths of Earth’s oceans, there is a growing need for the installation of subsea structures. 71% of the earth’s surface is ocean but there are limitations inherent in current detection instruments for marine applications leading to the need for the development of underwater platforms that allow research of deeper subsea areas. Several underwater platforms including Autonomous Underwater Vehicles (AUVs), Remote Operated Vehicles (ROVs), and wave gliders enable more efficient deployment of marine structures.
Deployable structures are able to be compacted and transported via AUV to their destination then morph into their final form upon arrival. They are a lightweight, compact solution. The wrapped package includes the deployable structure, underwater pump, and other necessary instruments, and the entire package is able to meet the payload capability requirements. Upon inflation, these structures can morph into final shapes that are a hundred times larger than their original volume, which extends the detection range and also provides long-term observation capabilities.
This dissertation reviews underwater platforms, underwater acoustics, imaging sensors, and inflatable structure applications then proposes potential applications for the inflatable structures. Based on the proposed applications, a conceptual design of an underwater tubular structure is developed and initial prototypes are built for the study of the mechanics of inflatable tubes. Numerical approaches for the inflation process and bending loading are developed to predict the inflatable tubular behavior during the structure’s morphing process and under different loading conditions. The material properties are defined based on tensile tests. The numerical results are compared with and verified by experimental data. The methods used in this research provide a solution for underwater inflatable structure design and analysis. Several ocean morphing structures are proposed based on the inflatable tube analysis.

In a tank filled with water at the bottom and oil floating on top, a straight rod reaching into the oil is set to rotate. The rotating rod is brought just above the oil/water boundary and is set to rotate at a speed greater than 200 revolutions per minute. It became evident that the rod’s rotation caused the oil/water interface to curve upward around the center of rotation, reaching up to the bottom of the rotating rod. Visible rings of water formed around the rod, starting at the bottom (at the oil/water interface) and ascending the rod, one by one. The water rings remained separate and ascended the rod until they eventually dispersed into the oil. Such quantization of water into rings has never been reported on before and represents a novel area of investigation in fluid dynamics. This study aims at obtaining quality photographic evidence to explain this phenomenon.

Abstract
Object of research is to improve a solar desalination device known as the Water Cone that creates potable water using solar energy. The water cone is a polymeric cone that sits overtop a dish of saline water. The water is evaporated by the sun and condenses back onto the surface of the cone creating fresh water. In an attempt to improve the cone’s water production, two different hydrophobic coatings are applied to the inside of two cones, which allow water droplets to flow at a much faster rate, collecting water more quickly. Two water cones are coated separately, and are exposed to sunlight for five days. Water collection for the coated portion of the cone is compared to the uncoated portion of the cone. Results after a first trial show that coating A on the water cone impedes water collection whereas coating B appears to increase water collection.

The purpose of this research was to explore dispersion patterns of coffee creamer when exposed to rotating fresh water. The dispersion patterns of the creamer were observed after being both added directly to the rotating water and when having to first traverse a layer of vegetable oil. A rotating platform supporting a beaker was controlled through a power supply. The power supply was adjusted and the dispersion patterns of the creamer were observed at 2, 4, and 6 volts. When added directly, at 2 and 6 volts, the coffee creamer displayed a pattern of swirling around the vertical axis with some dispersion radially towards the bottom of the beaker. At 4 volts bands were formed, which was likely the result of experimenter error. After the vegetable oil was added, the coffee creamer again displayed as swirls after crossing the oil but was not as distinct as when applied directly.

Within the framework of ongoing research studying the effects of oscillatory forces on pipe flow, an experiment was conducted to investigate the relationship between the nature of said forces and hydraulic jump resulting from the impact of the exiting flow onto an orthogonal surface.
To this end, a reservoir supplying constant head and near-hydrostatic conditions was equipped with an exit fitting in its lower section. A section of PVC tubing extended vertically downward from this exit point and was straddled by a pair of dynamic loudspeakers placed opposite each other and connected to a receiver's inputs so as to play a signal of specified frequency. The resulting turbulent jet flow was then allowed to drop to a horizontal plate of circular shape. The outer lip of the plate triggered a circular hydraulic jump whose location was found to be directly dependent on the frequency of the forces exciting the flow.

This thesis explores the feasibility of using morphing rudders in autonomous
underwater vehicles (AUVs) to improve their performance in complex current
environments. The modeling vehicle in this work corresponds to the Florida Atlantic
University's Ocean EXplorer (OEX) AUV. The AUV nonlinear dynamic model is
limited to the horizontal plane and includes the effect of ocean current. The main
contribution of this thesis is the use of active rudders to successfully achieve path
keeping and station keeping of an AUV under the influence of unsteady current force.
A constant ocean current superimposed with a sinusoidal component is considered.
The vehicle's response is analyzed for a range of current frequencies.

The purpose of this study is to utilize information and data gathered from previous studies pertaining to the BioRock® method, patented by Dr. W. Hibertz and T.J. Goreau in 1974. Biorock® stimulates the growth of coral reefs utilizing natural reef processes and electrochemistry to remove CO2 from the atmosphere. Our aim is to make the process more efficient to achieve large scale atmospheric carbon dioxide sequestration. A pH sensor in the water and CO2 sensor is in place to quantify and confirm the reduction of CO2 in the water and air above, all within a sealed tank. The first experiment in this study used an iron mesh with an electric current running through it to collect the limestone that serves as the base for a reef. However, the iron oxidized instead of collecting limestone. Future testing will utilize a lead plate as it is less susceptible to rusting.