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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. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

One of the basic problems which have to be solved by Unmanned Automated Vehicles (UAV) involves the computation of a motion plan that would enable the system to reach a target given a set of initial conditions in presence of uncertainties on the vehicle dynamics and in the environment. Recent research efforts in this area have relied on deterministic models. To address the problem of inevitable uncertainties, a low-level control layer is typically used to ensure proper robust trajectory tracking. Such decision-tracking algorithms correct model disturbances a posteriori, while the whole movement planning is done in a purely deterministic fashion. We argue that the decision making process that takes place during movement planning, as performed by experienced human pilots, is not a purely deterministic operation, but is heavily influenced by the presence of uncertainties and reflects a risk-management policy. This research aims at addressing these uncertainties and developing an optimal control strategy that would account for the presence of system uncertainties. The underlying description of UAV trajectories will be based on a modeling language, the Maneuver Automaton, that takes into full account the vehicle dynamics, and hence guarantees flyable and trackable paths and results in a discretized solution space. Two optimal control problems, a nominal problem omitting uncertainties and a robust problem addressing the presence of uncertainties, will be defined and compared throughout this work. The incorporation of uncertainties, will ensure that the generated motion planning policies will maximize the probability to meet mission goals, weighing risks against performance.

Resolving diversity patterns and their underlying drivers has application for both ecological theory and ocean management. Because seafloor characteristics are often used to assess bottom habitat, I examined the relationship between deep-sea benthic (bottom-living) diversity and multi-scale topographic heterogeneity. Most work occurred on the Canadian Pacific continental shelf at Learmonth Bank with additional sites in Strait of Georgia (BC) and Gulf of Maine (Atlantic shelf). High-resolution species distribution and seafloor data were annotated from remotely operated vehicle benthic imagery surveys while large-scale seafloor data were derived from multibeam sonar. New method development to address problems of current methods and to facilitate comparison among ecosystems is a major outcome. My new MiLS method (microtopographic laser scanning) can profile the deep seafloor at a resolution of ~1-2 cm with high accuracy and precision. I also developed a new ACR (arc-chord ratio) rugosity index as a measure of 3-D topographic heterogeneity that is simple, accurate and highly versatile. Model systems and scales vary among my studies but results consistently yield a positive relationship between diversity and topographic heterogeneity and identify bottom hydrodynamics as an important underlying driver. Rockfish Sebastes spp. associate with higher seafloor rugosity non-randomly and select for deep-sea corals and sponges over inert substrata alone. Data indicate that degradation of biogenic structures is a long-term detriment to rockfish species. Gorgonian coral- and sponge-dominant biotopes strongly associate with a single substratum type. These relationships were used to map coral and sponge distributions. This work, which collectively adds new information on the ecological relevance and distribution of corals and sponges, is pertinent to the conservation and management of fish stocks and vulnerable marine ecosystems. Epibenthic community variables abundance, richness, and Shannon diversity positively correlated with both the local microtopographic heterogeneity on a scale of 10 m2 and with the surrounding regional large-scale topographic heterogeneity on scales of 25 to 250,000 m2. Relationships were strongest between epibenthic community variables and the largest scale rugosity and were used to generate and test predictive diversity models. Where management strategies rely on surrogate measures in data-poor areas, mapping benthic diversity using ACR rugosity will provide good indicators. Although bottom hydrodynamics is consistently identified as an underlying driver of epibenthic patterns related to topographic heterogeneity, data suggest the nature of the relationship varies across spatial scales. At small scales, high topographic heterogeneity likely increases diversity by increasing the number of available niches (including hydrodynamic gradients; e.g., the abrupt vertical rugosity created by tall corals and sponges provides rockfish refuge from currents) while at large scales, high topographic heterogeneity increases local diversity less directly through distant hydraulic events that alter bottom flow hydrodynamics. / Graduate / 0329 / 0416 / 0799 / cdupreez@uvic.ca

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 172-178). Also available in electronic format on the Internet.

Philosophiae Doctor - PhD (Biodiversity and Conservation Biology) / Seawater temperature from regional to global scale is central to many measures of biodi- versity and continues to aid our understanding of the evolution and ecology of biolog- ical assemblages. Therefore, a clear understanding of the relationship between marine biodiversity and thermal structures is critical for effective conservation planning. In the an- thropocene, an epoch characterised by anthropogenic forcing on the climate system, future patterns in biodiversity and ecological functioning may be estimated from projected climate scenarios however; absent from many of these scenarios is the inclusion of extreme thermal events, known as marine heatwaves (MHWs). There is also a conspicuous absence in knowl- edge of the drivers for all but the most notorious of these events. Before the drivers of MHWs along the coast of South Africa could be determined, it was first necessary to validate the 129 in situ coastal seawater temperature time series that could be used to this end. In doing so it was found that time series created with older (longer), lower precision (0.5 Degrees Celsius) instruments were more useful than newer (shorter) time series produced with high precision (0.001 Degrees Celsius) instruments. With the in situ data validated, a history of the occurrence of MHWs along the coastline (nearshore) was created and compared against MHWs detected by remotely sensed data (offshore). This comparison showed that the forcing of offshore temperatures onto the nearshore was much lower than anticipated, with the rates of co-occurrence for events between the datasets along the coast ranging from 0.2 to 0.5. To accommodate this lack of consistency between datasets, a much larger mesoscale area was then taken around southern Africa when attempting to determine potential mesoscale drivers of MHWs along the coast. Using a self organising-map (SOM), it was possible to organise the synoptic scale oceanographic and atmospheric states during coastal MHWs into discernible groupings. It was found that the most common synoptic oceanographic pattern during coastal MHWs was Agulhas Leakage, and the most common atmospheric pattern was anomalously warmoverland air temperatures.With these patterns known it is now necessary to calculate how often they occur when no MHW has been detected. This work may then allow for the development of predictive capabilities that could help mitigate the damage caused by MHWs.

Submitted by Nádia Paes (nadia66paes@gmail.com) on 2016-09-30T14:19:37Z No. of bitstreams: 1 DISS_2015_Anna Carolina Natale Rodrigues.pdf: 1941878 bytes, checksum: 83d67286141efc175526c206f4b5d8a9 (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2016-09-30T16:16:19Z (GMT) No. of bitstreams: 1 DISS_2015_Anna Carolina Natale Rodrigues.pdf: 1941878 bytes, checksum: 83d67286141efc175526c206f4b5d8a9 (MD5) / Made available in DSpace on 2016-09-30T16:16:19Z (GMT). No. of bitstreams: 1 DISS_2015_Anna Carolina Natale Rodrigues.pdf: 1941878 bytes, checksum: 83d67286141efc175526c206f4b5d8a9 (MD5) Previous issue date: 2015-05-06 / CAPES / Aeronaves Remotamente Pilotadas, mais conhecidas como Drones nos textos da imprensa, são aeronaves que funcionam como dispositivos de vigilância e defesa, utilizados pelos Estados Unidos desde a Guerra do Vietnã. Por muito tempo esta tecnologia esteve nas mãos dos israelenses, mas, nos últimos anos, os Estados Unidos tornaram-se o maior produtor desse tipo de aeronave. A utilização desta tecnologia começou a se tornar conhecida no último governo Bush após os ataques de 11 de setembro com a chamada ‘Guerra ao Terror’. Mais recentemente, o governo Obama intensificou o seu uso, com o aumento de investimentos militares, fabricação e circulação desses dispositivos. Por mais que o uso civil desta tecnologia esteja aumentando, o foco da pesquisa ainda em andamento é a utilização dela no contexto militar, principalmente estadunidense. Há quase dois mil conflitos armados ao redor do mundo desde o novo milênio e o número cresce a cada dia. A violência legítima, a criminalidade e o terrorismo tornam-se indistinguíveis um do outro. Em decorrência disso, os termos de validação tendem a entrar em colapso. Os chamados drones podem ser operados a milhares de quilômetros de distância e costumam ser utilizados sem a autorização do espaço aéreo dos governos invadidos. Vive-se em um momento de conflitos difusos de pequenos inimigos em todo lugar e a utilização das Aeronaves Remotamente Pilotadas confirma a ideia da presença de um inimigo constante, e quando a guerra está na base da política, o inimigo tem a função constitutiva de legitimar a vigilância e os ataques. Se o inimigo não é mais concreto, compreensível e localizável sua aura é hostil, facilitando a legitimação daquilo que é na realidade insustentável. / Remotely Piloted Aircrafts also known through the press as Drones, are surveillance and defense devices used by The United States of America since the Vietnam war. For a long time, this technology was in the hands of the Israeli armed forces, but in the last few years, The United States became the largest producer of this aircraft. The use of Drones became known in the last Bush administration, after the attacks of September 11, with the so-called "War on Terror". Moreover, more recently in the Obama administration with the increasing manufacture of such devices. Even though the use of this technology among civilians are increasing, the focus of this ongoing research is its use in military context, mostly American. According to Hardt and Negri (2012), nowadays there are almost two thousand armed conflicts around the world since the new millennium. These numbers keep growing, therefore, the legitimate violence, crime and terrorism became indistinguishable from one another, the terms of validation tend to collapse. The remotely piloted aircrafts can be operated thousands of miles away and often without the airspace permission of the invaded governments. We are in a time of small and intern conflicts with small enemies everywhere. Moreover, using this aircraft confirms the idea of this constant enemy, and when war is at the base of politics, the enemy has the primary function to legitimate surveillance and attacks. If the enemy is no longer concrete, understandable and traceable, then its aura is hostile, facilitating the legitimacy of that is in reality unsustainable.

Dissertation (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011 / This paper presents the development of a data collection system for a small unmanned Aerial Vehicle (UAV) flight. The following three facets comprise of a UAV system: (1) a UAV aircraft; (2) onboard avionics; and (3) a ground control station subsystem (Taha et al., 2010:1). In this project, the UAV aircraft is based on the low-cost autonomous quad-rotator system named “Arducopter Quad”, where the onboard avionic system utilizes both an ArduPilot Mega (APM) on-board controller and IMU sensor shield, while the “Mission Planner” software operates as GCS software to gather essential flight data (Xiang & Tian, 2011:176). The approach provides the UAV system structure and both hardware and software with a small UAV data collection system, which is examined throughout the study. And introduce the concept of Arducopter dynamics for better understanding with its flight control. The study also considers the communication process between the UAV and the ground control station. The radio wave is an important aspect in the UAV data collection system (Austin, 2010:143). The literature review introduced the basis of the radio wave in respect of its travelling speed, and its characteristics of propagation, including how different frequencies will affect radio wave propagation. The aim of this project was to develop a platform for a small UAV real-time data collection system. The pendulum system was involved to simulate the “Roll” movement of the small UAV, while real-time IMU sensor data was successfully collected at ground control station (GCS), both serial communication and wireless communication, which was applied in the data collection process. The microwave generator interference test proves that the 2.4 GHz XBee module is capable of establishing reliable indoor communication between the APM controller and the GCS. The work of this project is towards development of additional health monitoring technology to prevent the safety issue of the small UAV. The data collection system can be used as basis for the future research of real-time health monitoring for various small UAVs.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2015. / Currently non-destructive testing techniques for composite aircraft structures are disadvantaged when compared to online Structural Health Monitoring (SHM) systems that monitor the structure while in-service and give real time data. The present research work looks at developing a protocol for online structural health monitoring of a UAV wing structure using PVDF film sensors, especially including the monitoring of structural changes caused by defects. Different types of SHM techniques were studied in relation to carbon fibre composites. Laminate composite make-up and manufacturing process was investigated and vacuum infusion process was used to manufacture the samples that resemble the Guardian II wing structure, then the three-point bending test was used to determine the material properties. Digital Shearography was employed as a stationery non-destructive technique to determine the sensor to structure attachment, type and position of defects that affect the state of performance. Finite Element Analysis (FEA) was done using ANSYS Workbench which served as a modelling tool using a drawing imported from Solid-works. Experimental investigation was done using PVDF sensor embedded on the surface of the sample in a cantilever setup and a vertical Vernier scale to measure the deflection due to impact and vibration loading. A Fluke-View oscilloscope was used as a data logger when the measurement of the output voltage and the natural frequency were recorded. The techniques of using FEA and experimental investigation were then compared. The findings of this study showed that the PVDF sensor is suitable for condition monitoring of a UAV wing structure.