Description: Provides a listing of current staff, committee members and society officers.

Description: High activity of seismic surveying in Norwegian waters has caused concerns about the impact the acoustic noise from the seismic airguns may have on marine life. There is evidence that this noise can cause reactions on the behavior of the fish resulting in reduced catches. To mitigate the problem and the conflict of interest between the fishing industry and the seismic exploration interest, the Norwegian Petroleum Directorate (NPD) commissioned SINTEF Information and Communication Technology (ICT, Trondheim, Norway) and the Department of Biology, University of Oslo (Oslo, Norway) to develop an acoustic–biological model to predict the impact of seismic noise on the fish population. The ultimate goal is to develop an acoustic–biological model to use in the design and planning of seismic surveys such that the disturbance to fishing interest is minimized. This acoustic module of the model is based on ray theory and can deal with range-dependent bathymetry and depth-dependent sound-speed profiles. The bottom is modeled as a sedimentary fluid layer over a solid elastic rock and the model requires the thickness and seismoacoustic properties of the sediments layer and the rock with compressional speed, shear speed, and absorption. The model simulates the total sound field, both in the time domain and in the frequency domain, out to very large distances. Calculated sound exposure levels are compared with startle response levels for cod. Preliminary conclusions indicate a required distance in the range of 5–10 km, but dependent on the depth and the season. In additions, under certain conditions, there will appear regions with hot spots where the sound level is significantly higher due to caustics and focusing of sound. Modeled results are compared with results obtained from a joint seismoacoustic survey conducted in summer 2009 at Vesterålen-Lofoten area (Nordland VII). In this experiment, signals were recorded at fixed hydrophone po- itions as the seismic vessel approached from a maximum distance of 30 km toward the receiving positions. The same situation was modeled using available geological and oceanographic information as input to the acoustic model. The agreement between the real and recorded signals and the model results is good. This indicates that in the future acoustic–biological models may be used in the design and planning of seismic surveys such that the disturbance to fishing is minimized.

Description: The fusion of several images of the same scene into a single and larger composite is known as photomosaicing. Unfortunately, the seams along image boundaries are often noticeable, due to photometrical and geometrical registration inaccuracies. Image blending is the merging step in which those artifacts are minimized. Processing bottlenecks and the lack of medium-specific processing tools have restricted underwater photomosaics to small areas despite the hundreds of thousands of square meters that modern surveys can cover. Large underwater photomosaics are increasingly in demand for the characterization of the seafloor for scientific purposes. Producing these mosaics is difficult due to the challenging nature of the underwater environment and the image acquisition conditions, including extreme depth, scattering and light attenuation phenomena, and difficulties in vehicle navigation and positioning. This paper proposes strategies and solutions to tackle the problems of very large underwater optical surveys (gigamosaics), presenting contributions in the image preprocessing, enhancing, and blending steps, resulting in an improved visual quality in the final photomosaic. A comprehensive review of the existing methods is also presented and discussed. Our approach is validated by a large optical survey of a deep-sea hydrothermal field, leading to a high-quality composite in excess of 5 Gpixel.

Description: This paper presents a control architecture for an autonomous underwater vehicle (AUV) named the Component Oriented Layer-based Architecture for Autonomy (COLA2). The proposal implements a component-oriented layer-based control architecture structured in three layers: the reactive layer, the execution layer, and the mission layer. Concerning the reactive layer, to improve the vehicle primitives' adaptability to unknown changing environments, reinforcement learning (RL) techniques have been programmed. Starting from a learned-in-simulation policy, the RL-based primitive cableTracking has been trained to follow an underwater cable in a real experiment inside a water tank using the Ictineu AUV. The execution layer implements a discrete event system (DES) based on Petri nets (PNs). PNs have been used to safely model the primitives' execution flow by means of Petri net building block (PNBBs) that have been designed according to some reachability properties showing that it is possible to compose them preserving these qualities. The mission layer describes the mission phases using a high-level mission control language (MCL), which is automatically compiled into a PN. The MCL presents agreeable properties of simplicity and structured programming. MCL can be used to describe offline imperative missions or to describe planning operators, in charge of solving a particular phase of a mission. If planning operators are defined, an onboard planner will be able to sequence them to achieve the proposed goals. The whole architecture has been validated in a cable tracking mission divided in two main phases. First, the cableTracking primitive of the reactive layer has been trained to follow a cable in a water tank with the Ictineu AUV, one of the research platforms available in the Computer Vision and Robotics Group (VICOROB), University of Girona, Girona, Spain. Second, the whole architecture has been proved in a realistic simulation of a whole cable tracking mission.

Description: Lists the reviewers who contributed to the IEEE Journal of Oceanic Engineering in 2012.

Description: Ceramics have some outstanding features that are necessary for pressure-tight housings, such as higher compressive strength, lower specific gravity, and higher resistance against corrosion. One promising application is pressure-tight housings for a free-fall popup ocean-bottom seismometer (OBS). Ceramic pressure-tight housings can provide sufficient strength and buoyancy even at 11-km water depth. Nevertheless, tensile and bending strengths of ceramics are only a fraction of their compressive strength. For metals, they are almost equal. Therefore, common design methods for pressure-tight housings are not directly applicable to ceramic pressure-tight housings. As described herein, we propose a new design method for ceramic pressure-tight housings, particularly a method of reinforcement of through-holes for underwater connectors. We also present detailed data that support the proposed design method.

Description: Advertisement: IEEE members have published visionary new technologies since 1884. Libraries and IEEE, leaders in technical knowledge.

Description: Autonomous underwater vehicles (AUVs) are frequently used for deep-water ocean applications such as surveying and cable laying, where accurate control of vehicle depth and attitude is needed. The water level in the onboard ballast tanks is typically manually set for neutral buoyancy before each mission, while the vehicle is on the surface. The ballast tank contents are not normally adjusted to control vehicle depth and orientation while the AUV is in operation. As a result, vehicle trajectory and orientation is exclusively controlled using the vehicle's control surfaces during a mission. The challenges with controlling the depth and trim of an underwater vehicle include nonlinear hydrodynamic forces, as well as inherent time delays (latencies) associated with water tank level changes and valve adjustments. Furthermore, small changes in the location of the vehicle's center of gravity (i.e., due to the deployment of the AUV's payload equipment) can reduce the control authority of the AUV's control surfaces. To meet these challenges, this paper proposes two unique variable ballast system (VBS) control approaches. The first proposed VBS controller changes the weight of the AUV to help control vehicle depth and vertical (inertial) velocity. The second proposed VBS controller attempts to shift the center of gravity $x_{G}$ along the body-fixed $x$ -(longitudinal)-axis to reduce depth and pitch angle error while restoring control authority to the bowplane and sternplane deflection fins. The ballasting system consists of two water tanks positioned aft and forward of amidships. The ballast tanks are then automatically filled or emptied of ocean water as desired. Numerical simulations have been carried out on a 2-D underwater vehicle simulator to test and compare the performance of the proposed ballast and fin deflection control systems. Th- simulation results show that, for the assumptions and conditions tested, the proposed controllers are capable of achieving a setpoint depth and pitch angle with minimal error by effectively utilizing the ballast tanks and deflection fins. As a result, the work presented in this paper helps increase the autonomy of large AUVs on long-duration missions.

Description: This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author's name. The primary entry includes the co-authors' names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author's name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index.