Sara Adams

Manoeuvring Experiments Using the MUN Explorer AUV

Autonomous Underwater Vehicles (AUVs) are self-propelled robotic platforms that can perform a predetermined mission completely unmanned. A series of manoeuvring experiments were performed using the MUN Explorer AUV during the summer of 2006 and a selection of these experimental results are presented in this paper. The purpose of these experiments was to collect a set of useful data for validating a hydrodynamic model of the dynamic performance of the vehicle. This paper aims at explaining the methods and measures adopted in accomplishing this task. Apart from providing a data set for validation of the hydrodynamic model, the data record also shows the ability of the AUV to perform extreme manoeuvres and the accuracy with which it can follow a pre-planned mission.

Analysis of horizontal zigzag manoeuvring trials from the MUN Explorer AUV

A series of full-scale zigzag manoeuvring trials were performed using a streamlined Autonomous Underwater Vehicle (AUV) - the MUN Explorer AUV during the summer of 2006. This paper presents the results and observations from the zigzag manoeuvres or the Z-tests performed in horizontal planes. Unlike the conventional method of performing a Z-test, these zigzags were performed by allowing the vehicle to follow a predefined path that was laid out in a zigzag pattern. The paper outlines briefly the method by which these tests were conducted and discusses the observations made.

Manoeuvring Trials with the MUN Explorer AUV: Data Analysis and Observations

Manoeuvring trials are usually performed to determine the manoeuvring characteristics of a marine vehicle. It is through certain standard manoeuvres we evaluate the robustness, performance and limitations of the vehicle control system. A series of open-water manoeuvring trials were performed using the MUN Explorer AUV in the summer of 2006. The actual purpose of these experiments was to collect a set of experimental data in order to validate a hydrodynamic model of the dynamic performance of the vehicle. This paper presents the results and observations from the analysis of a set of manoeuvring trials data: in particular the results from straight- line (acceleration - deceleration) tests and turning circles. It outlines briefly the method by which these tests were conducted and discusses the results and observations made. Apart from providing a data set for validation purposes, the results also indicate the ability of the vehicle to follow a pre-planned mission with precision.

Ocean Outfall Mapping Using an Autonomous Underwater Vehicle

Ocean outfalls are difficult to observe and the traditional monitoring methods are expensive and can only provide limited information. As an alternative, Autonomous Underwater Vehicles (AUVs) have proved to be an effective tool for outfall mapping. This paper describes an outfall mapping mission by the MUN Explorer AUV off the east coast of Canada. A submerged freshwater outfall with Rhodamine WT dye was discharged into a bay and the MUN Explorer AUV equipped with a fluorometer was used to measure the dye concentration and the extent of the dispersed plume. The results have shown that the AUV can be effectively used to map the outfall and future work is needed to provide more detailed plume information.

Environmental monitoring of fish plant effluent in coastal Newfoundland

Offal from fish processing plants represents the largest organic waste stream in Newfoundland. It is important to understand the spatial dispersion properties of the waste to assess if there are possible options for waste management that may be advantageous to implement. Preliminary studies of a crab-processing plants effluent were conducted in October 2004 whereby rhodamine WT, a common dye tracer was added to the effluent of a plant in Aquaforte, Newfoundland. Measurements were taken with a fluorometer, CTD (conductivity, temperature and depth) and dissolved oxygen sensor mounted on the back of an 18 ft inflatable boat equipped with an electric trolling motor to limit plume disturbance. Continuous spatial data corresponding to the sensor information was obtained using a GPS unit in the boat. Spatial and oceanographic data were integrated to obtain a visual and quantitative representation of the plume. A comparison of the actual plume was conducted with a plume dispersion model developed through the use of the plume modeling software, CORMIX and a geographic information system (GIS) to determine if there are any similarities.

Preparatory Tests with an Explorer class Autonomous Underwater Vehicle for Missions under Sea Ice

The autonomous underwater vehicle (AUV) operations described here are preparatory missions to enable operation of an AUV under sea ice in polar regions. The proposed polar projects include operations under land fast ice in the Arctic through an ice moon pool and a planned project to assess sea ice mass balance and habitat assessment in the Southern Ocean in East Antarctica. This paper focuses on the preparatory missions, done in open water, and the planned Southern Ocean project. The plan is to use an autonomous underwater vehicle (AUV) for the under ice component of measurements. The ultimate goals are to quantify the size and shape of ridge keel structures and their contribution to the sea ice mass balance over a study region; to understand the processes that link sea ice with the distribution of ice algae and krill; to provide the necessary field measurements, over sufficiently large areas, for the calibration/validation of satellite and aircraft-based measurements of the sea ice and snow cover thickness; and to provide baseline measurements of sea ice thickness for future climate monitoring.

A comparison of PAHs in produced water discharges and flared gas emissions to the ocean

Produced water represents the single largest source of marine pollution in terms of toxicity and volume from an offshore platform in the production stage of oil and gas operations. In the past few years increasing attention has focused on the presence and possible impact of polycyclic aromatic hydrocarbons (PAH) in produced water. Studies have shown that the concentration of the 16 EPA PAHs can vary from 0.7 to 100s mg/L in produced water. However, particularly on oil platforms, the flaring of produced gas can also be a significant source of PAHs. A study by the Alberta Research Council in 1996 identified many PAHs in the emissions from the flared produced gas (up to 300 mg/m/sup 3/ for the 16 EPA PAHs). It is likely that much of the PAHs in the flared emissions will end up in the water and so should be assessed against the produced water input of PAHs. However, it is difficult to compare concentrations in the flared emissions and produced water outfall directly as the dispersion in each media, characteristics of the flare stack and outfall, and meteorological conditions are all factors in mass input into the water. In this study the concentration of PAHs in the emissions was converted to an emission rate and input into an air dispersion model. The maximum ground level concentrations were determined with the model and then converted to a seawater concentration using a simple equilibrium model. The produced water outfall was simulated using CORMIX and the resulting concentrations were compared with the air dispersion model results.