Ocean Engineering Commons^™

Sensor Development To Utilize Underwater Electric Potential (Uep) Fields To Navigate The Underwater Areas Of Ship Hulls, Caglar Erdogan

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Underwater electric potential fields occur due to natural reasons, such as changes in atmosphere, ionosphere, magnetosphere, and movements of water bodies in the ocean, or artificial reasons, such as stray and controlled electric currents, or both. Electric potential fields around ship hulls are mainly generated due to corrosion protection systems and dissimilar materials. The electric field intensity over an impressed current anode of a large cruise ship operating in with seawater with a resistance of 20 0-cm is around 90 mV/cm, whereas it is between 0.4 and 1 mV/cm on a propeller for the same ship. The theoretical field intensities …

Surf Zone Tilt Current Meter, Troy Heitmann

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Coastal tides and free surface gravity waves locally interact with the nearshore bathymetry generating spatially diverse circulation cells. Collectively, the cells form a current velocity flow field where net transport of geological, chemical, or biological, particulates takes place. Within the surf zone, dynamic instabilities lead to chaotic evolution and mixing, where single point, observations fail to quantitatively char­acterize the system as a whole. Governed by advanced theories, numerical models provide the necessary sampling resolution to study surf zone processes over large do­mains, but the model must be validated with field observations to draw meaningful conclusions. The acoustic Doppler current profiler …

Developing In Situ Dissolved Inorganic Carbon Dioxide Instrumentation, Beckett Colson

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

The ocean carbon system plays a critical role in regulating carbon dioxide content in the atmosphere. With increased anthropogenic carbon input, it is even more important to understand the system through measurements, models, and predictions. Unfortunately, the spatiotemporal resolution of ocean carbon system measurements is limited by a lack of in situ instrumentation. The support of the Link Foundation Ocean Engineering and Instrumentation Fellowship has enabled me to make significant progress in developing an in situ carbon system instrument for the deep sea. The instrument will measure both total dissolved inorganic carbon (DIC) and the partial pressure of carbon dioxide …

Link Foundation Fellowship Report, Eric Nieves

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Magnetic anomaly detection (MAD) is a leading technique for the detection and localization of obscured magnetic targets via exploiting the field anomalies they create. This is especially true in marine environments when looking for unexploded ordnance (UXO), because the DC magnetic field is not highly influenced by numerous types of media (i.e. water) or weather conditions. MAD is also a passive technique, which allows it to go unnoticed by the target. Whereas current applications of MAD have been shown to be effective for localizing single targets at a time, the development of a method for multiple localization would the robustness …

A Shipboard Instrument For Underway Estimates Of Marine N2 Fixation, Weiyi Tang

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Marine N2 fixation converts nitrogen gas into ammonia and accounts for the largest external nitrogen input to the oceans1. Since large portions of the global oceans are nitrogen deficient, marine N2 fixation can relieve the nitrogen limitation, thereby increasing the growth of phytoplankton and stimulating biological uptake of atmospheric carbon dioxide2,3,4. However, the magnitude and distribution of marine N2 fixation are poorly constrained5. In addition, the environmental controls on marine N2 fixation remain elusive6. This situation is in part attributable to the limited number of observations and poor coverage of marine N2 fixation measurements. Current observations rely on discrete sampling …

Intelligent Supervisory Switching Control Of An Unmanned Surface Vehicle, Ivan Rodrigues Bertaska

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

The project originally proposed for this fellowship focused on developing a framework for multimodal control of an unmanned surface vehicle (USV) – transitioning it from an underactuated system to an overactuated one. This would assist in two main functions USVs are typically tasked with: transiting and station-keeping. This project has since expanded to encompass novel territory in control theory, robotics, and computer science. The author is hopeful that the work reported here will assist in the transition of USVs from an academic pursuit into a valuable, pervasive tool for the oceanic sciences and the ocean industry. For the continued expansion …

A Novel In Situ Microscope For Studying Benthic Organisms, Andrew Mullen

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Coastal marine ecosystems such as coral reefs, kelp forests, sea grass beds and mangroves have significant societal value. As economic resources they support tourism, fisheries and storm protection while ecologically they host high biological diversity and productivity. Many basic biological, chemical, and physical processes taking place in these marine ecosystems occur at ‘micro-­‐scales’ less than a millimeter in size. Examples of significant micro-­‐scale activities include: coral bleaching of their single-­‐ celled symbiotic algae, larval settlement and attachment, competition between sessile organisms along thin interfaces, and fluxes of particles to and from the seafloor. It is also important to consider that …

Bio-Inspired Flow Sensing For Underwater Guidance And Navigation, Levi Devries

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Stream-dwelling fish and aquatic mammals have an innate ability to navigate often-tumultuous environments with impressive precision, a highly desirable trait for underwater vehicle applications. For example, trout use their lateral line to sense vortices shed by an upstream obstacle and slalom between the vortices to reduce energy expenditure compared to free-stream swimming [3]. Moreover, harbor seals can use their whiskers to follow the trail of flow disturbances created in the wake of an object that has passed minutes before [4]. Recent developments in materials science have produced sensors that can measure local flow velocity similar to seal whiskers, and integration …

Model Based Adaptive Control Of Underwater Vehicles For Improved Ocean Science, Christopher J. Mcfarland

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Recent advances in unmanned underwater vehicle (UUV) capabilities have enabled oceanographic scientists to consider addressing research topics previously thought impractical or impossible. One such topic is the validation of high resolution computer models; long term deployments of coordinated UUV survey teams have been proposed to collect the density of measurements required. Another topic is the study of biological diversity in volatile areas; UUV intervention/sampling deployments have been proposed because of the inherent risks. In general, providing a high density of high accuracy measurements requires passing many targets as quickly and closely as possible. Similarly, efficacy for intervention/sampling deployments requires agile …

Predicting Underwater Radiated Noise From Offshore Impact Pile Driving, Huikwan Kim

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Offshore wind turbines have been installed throughout Europe and are expected to be built in the United States water shortly. Offshore wind is an attractive option because 53% of the nation’s population lives in coastal area where energy cost and demands are high. Offshore winds tend to blow harder and more uniformly than on land [1]. However, structure borne noise and vibration generated by offshore impact pile driving radiate into and propagate through the air, water, and sediment media. The objective of this project is quantitatively predicting noise level around the piling location at sea to estimate the effects of …

Underwater Object Detection And Identification Using Distributed Pressure Sensors, Audrey Maertens

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Underwater vision is usually limited. Object detection and identification is therefore one of the main challenges of underwater navigation. A new sensing modality, specifically developed for underwater environments, would greatly increase the scope of underwater missions. Taking inspiration from the lateral line of fish, I believe that pressure sensing can be a viable alternative to vision in order to detect and identify obstacles. Recent advances in the area of micro-engineering will soon enable to build sensors that match the size and mimic the functions and organization of the lateral line. However, little is known about how the pressure distribution along …

Advanced Underwater Vehicle Navigation, M. Jordan Stanway

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Underwater vehicles–both manned and unmanned–are critical in our efforts to explore and study the depths of the ocean. Most underwater sensors possess a relatively small field of view; this means they must be carried over large distances to achieve high spatial coverage and resolution. The vast amount of data these sensors collect is much more valuable if the location of the vehicle is precisely known at the time the data is collected. This gives rise to the maxim: The data is only as good as the navigation. Navigation remains a challenging problem for underwater vehicles. Fundamental limitations of sensing technology …

Turbulence Measurement With Coherent Doppler Sonar, Jeremy Dillon

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

The ocean has been described as Earth's "fi nal frontier" in a vision statement on ocean exploration (National Oceanic and Atmospheric Administration, 2000). The search for new insight is motivated by the fact that our environmental and economic security depends critically on the ocean and the freshwater bodies that drain into it. As the vast majority of the ocean is unknown and unexplored, there is great potential for scientifi c discovery beneath the sea surface (McNutt, 2002). The development of remote and in situ sensors forms a cornerstone of this vision for exploring ocean dynamics at new scales.

Investigation And Modeling Of Ice Fracture In Cold Ocean Engineering Applications, Rocky S. Taylor

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Ice conditions present a significant challenge in the design of ships and structures for the development of offshore energy resources in cold ocean environments. Many regions throughout the world including Alaska, Canada, Russia, Norway, Kazakhstan and China are developing offshore energy resources in ice-prone environments. The growth and stability of the global economy is closely linked to that of our energy supply, and offshore industrial activity in Northern regions has increased significantly in recent years. One of the most significant engineering challenges when designing structures for ice environments is the estimation of design ice loads. The design load scenario for …

Dynamics Of Wave-Current Boundary Layers Over Very Rough Boundaries, Marion Bandet-Chavanne

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

In this study, acoustic profiling techniques are used to resolve the two-dimensional spatial structures of the oscillating boundary layer in a phase-averaged sense over a wave orbital amplitude. The principal objective of this work is to examine the spatial variability of turbulent properties over irregular roughness. Field observations are used to investigate the interaction between bottom roughness, flow structure and turbulent properties within the near-bed flow. The overall focus of the research is to relate wave energy dissipation or friction factor estimates to physical roughness elements and understand the dynamics of such processes in the near-bed flow.

Semi-Autonomous Control Of Autonomous Underwater Vehicles, Stephen C. Martin

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

The goal of my graduate research is to address two engineering science problems whose solution will enable Autonomous Underwater Vehicles (AUVs) to routinely perform semi-autonomous missions presently considered impractical or infeasible. I am pursuing this research under the direction of Professor Whitcomb in the Dynamical Systems and Controls Laboratory at Johns Hopkins University, and in collaboration with the faculty of the Deep Submergence Laboratory of the Woods Hole Oceanographic Institution (WHOI).

In the last decade AUVs have begun to complement Human Occupied Vehicles (HOVs) and Remotely Operated Vehicles (ROVs) as effective platforms for oceanographic exploration. HOVs and ROVs are highly …

Performance Enhancement Of The Wirewalker Wave-Powered Profiler, Jonathan Pompa

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

The Wire-Walker is a wave-powered vertical profiler made for carrying oceanographic instruments. It cycles continuously through the depth range set by the user, providing a traveling platform for sensors. To achieve high data resolution in time varying environments, the Wire-Walker was redesigned from its original configuration for higher profiling speed. Improvements were made to the WireWalker profiler by using a numerical simulation of the system dynamics. Each physical parameter was varied in the model to find its effect on the profiling speed. Using the guidelines from the modeling experiment, a new WireWalker was constructed and tested in the ocean. The …