As part of a project to study internal waves, FAU plans to utilize an AUV to tow a magnetometer to study electromagnetic signatures from internal waves. This research is focused on the electromagnetic noise issues related to using an AUV to tow the magnetic sensor package. There are active sources of electromagnetic noise caused by an AUV that are present in addition to those induced by the Earth's magnetic field and permanent magnets. To characterize the magnetic noise associated with the AUV magnetometer tow system, the various active source elements were identified, the orientation sensitivity of the sensors being used was determined, and the magnetic anomaly of a similar AUV which may be eventually be used in a magnetic sensing arrangement was measured. The results are used to show the proposed sensing arrangement will likely not achieve the necessary sensitivity to measure subtle internal wave signals. / by Dylan Tilley. / Vita. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

To determine the effect of body shape on the response of underwater vehicles to surface waves in shallow water, the wave radiation hydrodynamic forces are evaluated for a family of (i) prolate spheroidal hull forms and (ii) cylindrical bodies with hemispherical nose and conical tail sections by systematically varying the geometric parameters but keeping displacement constant. The added-mass and wave damping coefficients are determined using a frequency-domain, simple-source based boundary integral method. Results are obtained for a range of wave frequencies and depths of vehicle submergence all for a fixed water depth of 10 m. With the wave exciting force and moment determined using the Froude-Krylov theory, the response transfer functions for heave and pitch are then determined. The heave and pitch response spectra in actual littoral seas are then determined with the sea state modeled using TMA spectral relations. Results show that vehicle slenderness is a key factor affecting the hydrodynamic coefficients and response. The results show two characteristics that increase the radiation hydrodynamic forces corresponding to heave and pitch motions: namely, vehicle length and further-away from mid-vehicle location of the body shoulder. The opposite is true for the oscillatory surge motion. By utilizing these observed characteristics, one can design the lines for maximum radiation forces and consequently minimum hull response for the critical modes of rigid-body motion in given waters and vehicle missions. In the studies carried out in the thesis, a hull with a long parallel middle body with hemispherical nose and conical tail sections has better heave and pitch response characteristics compared prolate spheroid geometry of same volume. The methodology developed herein, which is computationally efficient, can be used to determine optimal hull geometry for minimal passive vehicle response in a given sea. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

A magnetometer with a sensitivity of 0.01nT will be towed through the thermocline by a 2.87 meter long, 0.533 meter diameter autonomous underwater vehicle (AUV) to measure the magnetic fluctuations generated by oceanic internal waves. At this point, no research has been found that suggests towed magnetometer measurements have been done using an AUV. Simulations of the AUV, tow cable, and towfish are performed to provide an understanding of the effects of changing different input parameters, such as towing speed (0.5-2m/s), cable length (5-15m), vehicle trajectory (circle and vertical zig zag maneuvers), and current (0.25-1.25m/s). The AUV-cabletowfish system and equations of motion needed for the simulations are described herein. Results show that a 5m tow cable provides better towfish maneuvering than the longer cable lengths. High towfish pitch angle is decreased by decreasing the distance between CG and CB. Surface currents speed of 0.25m/s change the AUV and towfish circle maneuver to a spiral trajectory, while 1.25m/s current speed cause a zig zag trajectory. / by Lea Gabrielle Miller. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

The design, implementation, and testing of an experimental setup intended to evaluate the dynamic maneuvering performance of the Wave Adaptive Modular Vessel (WAM-V) class USV12, a 3.7 meter unmanned surface vehicle (USV) is described. A comprehensive sensor package was designed, fabricated and assembled to record the vehicle's dynamic response to various control inputs. All subsystems were fabricated and installed on a test vehicle, GUSS, and full system, open-loop maneuvering tests were conducted to show validity of data collection technique. Simulations were performed using model parameters found in the literature to create a "simulated experimental" data set, upon which system identification techniques were used to rediscover a suitable model with similar parameterization. Combined, the sensor package and the method for creating this model support future work in the design of automatic control, navigation, and guidance systems for the WAM-V USV12. / by Janine L. Mask. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

The design and integration of an unmanned surface vehicle (USV) control system is described. A survey of related work in both USV control, and unmanned vehicle operating software is presented. The hardware subsystem comprising a modular Guidance, Navigation, and Control (GNC) package is explained. A multi-threaded software architecture is presented, utilizing a decentralized, mutex-protected shared memory inter-process communication subsystem to provide interoperability with additional software modules. A generic GNC approach is presented, with particular elaboration on a virtual rudder abstraction of differential thrust platforms. A MATLAB Simulink simulation is presented as a tool for developing an appropriate controller structure, the result of which was implemented on the target platform. Software validation is presented via a series of sea trials. The USV was tested both in open- and closed-loop control configurations, the results of which are presented here. Lastly recommendations for future development of the GNC system are enumerated. / by Thomas C. Furfaro. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

Underwater vehicles often use acoustics or dead reckoning for global positioning, which is impractical for low cost, high proximity applications. An optical based positional feedback system for a wave tank operated biomimetic station-keeping vehicle was made using an extended Kalman filter and a model of a nearby light source. After physical light model verification, the filter estimated surge, sway, and heading with 6 irradiance sensors and a low cost inertial measurement unit (~$15). Physical testing with video feedback suggests an average error of ~2cm in surge and sway, and ~3deg in yaw, over a 1200 cm2 operational area. This is 2-3 times better, and more consistent, than adaptations of prior art tested alongside the extended Kalman filter feedback system. The physical performance of the biomimetic platform was also tested. It has a repeatable forward velocity response with a max of 0.3 m/s and fair stability in surface testing conditions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2013. / Cataloged from PDF version of thesis. / Includes bibliographical references. / Coastal and estuarine environments experience large variability and rapid shifts in pCO₂ levels. Elevated pCO², or ocean acidification, often negatively affects early life stages of calcifying marine invertebrates, including bivalves, but it is unclear which developmental stage is most sensitive. I hypothesized that initial calcification is a critical stage during which high pCO₂ exposure has severe effects on larval growth and development of bay scallop (Argopecten irradians). Using five experiments varying the timing of exposure of embryonic and larval bay scallops to high CO₂, this thesis identifies two distinct stages of development during which exposure to high CO₂/low pH causes different effects on bay scallop larvae. I show that any exposure to high CO₂ consistently reduces survival of bay scallop larvae. I also show that high CO₂ exposure during initial calcification (12-24 h post-fertilization) results in significantly smaller shells, relative to ambient conditions, and this size decrease persists through the first week of development. High CO₂ exposure at 2-12 h post-fertilization (pre-calcification), does not impact shell size, suggesting that the CO₂ impact on size is a consequence of water chemistry during calcification. However, high CO₂ exposure prior to shell formation (2-12 h post-fertilization) causes a high incidence of larval shell deformity, regardless of CO₂ conditions during initial calcification. This impact does not occur in response to high CO₂ exposure after the 2-12 h period. The observations of two critical stages in early development has implications for both field and hatchery populations. If field populations were able to time their spawning to occur during the night, larvae would undergo initial calcification during the daytime, when CO₂ conditions are more favorable, resulting in larger veliger larvae. Hatcheries could invest minimal resources to monitor and modify water chemistry only during the first day of development to ensure larva are exposed to favorable conditions during that critical period. / by Meredith Megan White. / Ph.D.

Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2017. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 169-182). / Protists play important roles in grazing and nutrient recycling, but quantifying these roles has been hindered by difficulties in collecting, culturing, and observing these often-delicate cells. During long-term deployments at the Martha's Vineyard Coastal Observatory (MVCO) (Massachusetts, USA), Imaging FlowCytobot (IFCB) made it possible to study live cells in situ without the need to culture or preserve. IFCB records images of cells with chlorophyll fluorescence above a trigger threshold, so taxonomically resolved analysis of protists is limited to mixotrophs and herbivores, which have eaten recently. To overcome this limitation, I coupled a broad-application 'live cell' fluorescent stain with a modified IFCB so that protists which do not contain chlorophyll (such as consumers of unpigmented bacteria and other heterotrophs) can also be recorded. Staining IFCB (IFCB-S) revealed higher abundances of grazers than the original IFCB, as well as some cell types not previously detected. To analyze a 10-year time series of herbivorous ciliates at MVCO and address broad patterns of seasonality of major ciliate classes and their components, I employed a statistical model that estimates a seasonal density pattern and simultaneously accounts for and separates any annual-scale effects. I describe the seasonality of three functional groups: a phototrophic ciliate, a mixotroph, and a group of strict heterotrophs, and comment on potential drivers of these patterns. DNA sequencing has also contributed to the study of protist communities, providing new insight into diversity, predator-prey interactions, and discrepancies between morphologically defined species and genotype. To explore how well IFCB images can be used to detect seasonal community change of the class Spirotrichea, an important and numerous group, I used high-throughput sequencing (HTS), which does not discriminate between chlorophyll-containing cells and the rest of the community. I report on species and genera of ciliates for which morphotype and genotype displayed high congruency. In comparing how well temporal aspects of genotypes and morphotypes correspond, I found that HTS was critical to detect and identify certain ciliates occupying a niche associated with warmer temperatures. I further showed that when these types of analyses are combined with IFCB results, they can provide hypotheses about food preferences. / by Emily Fay Brownlee. / Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICHROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Bradley James Deghuee. / M.S.

Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 131-143). / Coral reefs are biodiverse ecosystems that are at risk of degradation as a result of environmental changes. Reefs are constantly in a state of flux: the resident species assemblages vary considerably in space and time. However, the drivers of this variability are poorly understood. Tracking these changes and studying how coral reefs respond to natural and anthropogenic disturbance can be challenging and costly, particularly for reefs that are located in remote areas. Because many reef animals produce and use sound, recording the ambient soundscape of a reef might be one way to efficiently study these habitats from afar. In this thesis, I develop and apply a suite of acoustics-based tools to characterize the biological and anthropogenic acoustic activity that largely comprises marine soundscapes. First, I investigate links between reef fauna and reef-specific acoustic signatures on coral reefs located in the U.S. Virgin Islands. Second, I compare those findings to a more expansive study that I conducted in Maui, Hawaii, in which the drivers of bioacoustic differences among reefs are explored. Third, I investigate the distances over which sounds of biological origin may travel away from the reef and consider the range within which these acoustic cues might be usable by pelagic larvae in search of a suitable adult habitat. Fourth, I assess the extent to which the presence of vessel noise in shallow-water habitats changes the ambient soundscape. Finally, I present the results of a modeling exercise that questions how ocean noise levels might change over the next two decades as a result of major projected increases in the number and size of and distance traveled by commercial ships. The acoustics-based tools presented here help provide insight into ecosystem function and the extent of human activity in a given habitat. Additionally, these tools can be used to inform an effective regulatory regime to improve coral reef ecosystem management. / by Maxwell Bernard Kaplan. / Ph. D.