Inter-carrier interference mitigation for underwater acoustic communications

Communicating at a high data rate through the ocean is challenging. Such communications must be acoustic in order to travel long distances. The underwater acoustic channel has a long delay spread, which makes orthogonal frequency division multiplexing (OFDM) an attractive communication scheme. However, the underwater acoustic channel is highly dynamic, which has the potential to introduce significant inter-carrier interference (ICI). This thesis explores a number of means for mitigating ICI in such communication systems. One method that is explored is directly adapted linear turbo ICI cancellation. This scheme uses linear filters in an iterative structure to cancel the interference. Also explored is on-off keyed (OOK) OFDM, which is a signal designed to avoid ICI.

People and their past : is 'community archaeology’ the future?

This thesis looks at how ‘community archaeology’ ideals may influence an inclusive approach to Indigenous heritage management, ensuring Indigenous community power over processes to identify both past and present values of Country. Community archaeology was acclaimed by research archaeologists over a decade ago as a distinctive approach with its own set of practices to incorporate the local community’s perspectives of its past and current associations with place. A core feature of this approach in Australia is the major role the Indigenous community has in decisions about its heritage. Concurrently, considerable concern was being expressed that Indigenous heritage was not sufficiently addressed in environmental impact assessment processes ahead of development. Seen as absent from the process was the inclusion of Indigenous knowledge about both the pre- and post-contact story as well as any scientific advance in understanding an area’s Indigenous history. This research examines these contrasting perspectives seeking to understand the ideals of community archaeology and its potential to value all aspects of Indigenous heritage and so benefit the relevant community. The ideals of community archaeology build on past community collaborations in Australia and also respond to more recent societal recognition of Indigenous rights, reflected in more ethically inclusive planning and heritage statutes. Indigenous communities expressed the view that current systems are still not meeting these policy commitments to give them control over their heritage. This research has examined the on-the-ground reality of heritage work on the outskirts of Canberra and Melbourne. The case studies compare Victorian and ACT heritage management processes across community partnerships with public land managers, and examine how pre-development surveys operate. I conclude that considerable potential for achieving community archaeology ideals exists, and that they are occasionally partially realised, however barriers continue. In essence, the archaeological model persists despite a community archaeology approach requiring a wider set of skills to ensure a comprehensive engagement with an Indigenous community. Other obstacles in the current Indigenous heritage management system include a lack of knowledge and communication about national standards for heritage processes in government agencies and heritage consultants; the administrative framework that can result in inertia or silos between relevant agencies; and funding timeframes that limit possibilities for long-term strategic programs for early identification and management planning for Indigenous heritage. Also, Indigenous communities have varying levels of authority to speak for how their heritage should be managed, yet may not have the resources to do so. This thesis suggests ways to breach these barriers to achieve more inclusive Indigenous heritage management based on community archaeology principles. Policies for a greater acknowledgement of the Indigenous community’s authority to speak for Country; processes that enable and early and comprehensive ‘mapping’ of Country, and long-term resourcing of communities, may have been promised before. In this research I suggest ways to realise such goals.

An explanatory model of underwater adaptation

The underwater environment is an extreme environment that requires a process of human adaptation with specific psychophysiological demands to ensure survival and productive activity. From the standpoint of existing models of intelligence, personality and performance, in this explanatory study we have analyzed the contribution of individual differences in explaining the adaptation of military personnel in a stressful environment. Structural equation analysis was employed to verify a model representing the direct effects of psychological variables on individual adaptation to an adverse environment, and we have been able to confirm, during basic military diving courses, the structural relationships among these variables and their ability to predict a third of the variance of a criterion that has been studied very little to date. In this way, we have confirmed in a sample of professionals (N = 575) the direct relationship of emotional adjustment, conscientiousness and general mental ability with underwater adaptation, as well as the inverse relationship of emotional reactivity. These constructs are the psychological basis for working under water, contributing to an improved adaptation to this environment and promoting risk prevention and safety in diving activities.

A surface plasmon resonance system for the underwater detection of domoic acid

Over the past decade Surface Plasmon Resonance (SPR) techniques have been applied to the measurement of numerous analytes. In this article, an SPR biosensor system deployed from an oceanographic vessel was used to measure dissolved domoic acid (DA), a common and harmful phycotoxin produced by certain microalgae species belonging to the genus Pseudo-nitzschia. During the biosensor deployment, concentrations of Pseudo-nitzschia cells were very low over the study area and measured DA concentrations were below detection. However, the in situ operational detection limit of the system was established using calibrated seawater solutions spiked with DA. The system could detect the toxin at concentrations as low as 0.1 ng mL−1 and presented a linear dynamic range from 0.1 ng mL−1 to 2.0 ng mL−1. This sensor showed promise for in situ detection of DA.

International workshop on "Different survey methods for coral reef fish, including methods based on underwater video"

In September 2013, staff from the University of the South Pacific (USP) Honiara campus, the Secretariat of the Pacific Community (SPC) and IFREMER (UR LEADNC, AMBIO project) in New Caledonia, and the French Institute for Pacific Coral Reefs (IRCP) in Moorea, French Polynesia, co-facilitated a workshop entitled “Different survey methods of coral reef fish, including the methods based on underwater video”. The workshop was attended by students from USP, NGO and fisheries officers. They were trained to several underwater visual census techniques and to the STAVIRO video-based technique, including both field work and data analysis.

Underwater acoustic networks: the FP7 UAN project

The EU-funded project UAN - Underwater Acoustic Network aims at conceiving, developing and testing at sea an innovative and operational concept for integrating in a unique communication system submerged, surface and aerial sensors with the objective of protecting off-shore and coastline critical infrastructures. A crucial aspect of the project consisted in the use of autonomous underwater vehicles (AUVs) as mobile nodes in the underwater acoustic communication network. In particular, AUVs have the role of adapting the network geometry to the variation of the acoustic channel. This paper reports on the project concept and vision as well as on the progress of its various development phases. The recent at-sea successes that have been demonstrated within the UAN framework are detailed and results of the final UAN project demonstration, UAN11, held in the May of 2011, are reported. The UAN network was in operation for five continuous days with up to five nodes, of which three of them were mobile nodes. © IFAC.

Libs in cultural heritage: recognition and identification of objects in an underwater archaeological shipwreck

Nowadays, one of the most important areas of interest in archeology is the characterization of the submersed cultural heritage. Mediterranean Sea is rich in archaeological findings due to storms, accidents and naval battles since prehistoric times. Chemical analysis of submerged materials is an extremely valuable source of information on the origin and precedence of the wrecks, and also the raw materials employed during the manufacturing of the objects found in these sites. Nevertheless, sometimes it is not possible to extract the archaeological material from the marine environment due to size of the sample, the legislation or preservation purposes. In these cases, the in-situ analysis turns into the only alternative for obtaining information. In spite of this demand, no analytical techniques are available for the in-situ chemical characterization of underwater materials. The versatility of laser-induced breakdown spectroscopy (LIBS) has been successfully tested in oceanography 1. Advantages such as rapid and in situ analysis with no sample preparation make LIBS a suitable alternative for field measurements. To further exploit the inherent advantages of the technology, a mobile fiber-based LIBS platform capable of performing remote measurements up to 50 meters range has been designed for the recognition and identification of artworks in underwater archaeological shipwrecks. The LIBS prototype featured both single-pulse (SP-LIBS) and multi-pulse excitation (MP-LIBS) 2. The use of multi-pulse excitation allowed an increased laser beam energy (up to 95 mJ) transmitted through the optical fiber. This excitation mode results in an improved performance of the equipment in terms of extended range of analysis (to a depth of 50 m) and a broader variety of samples to be analyzed (i.e., rocks, marble, ceramics and concrete). In the present work, the design and construction considerations of the instrument are reported and its performance is discussed on the basis of the spectral response, the remote irradiance achieved upon the range of analysis and its influence on plasma properties, as well as the effect of the laser pulse duration and purge gas to the LIBS signal. Also, to check the reliability and reproducibility of the instrument for field analysis several robustness tests were performed outside the lab. Finally, the capability of this instrument was successfully demonstrated in an underwater archaeological shipwreck (San Pedro de Alcántara, Malaga).

Underwater swarm robotics review

Underwater robotics is a growing field in which more research is required. A literature review has been conducted on underwater robotics, focusing on the swarm problem with this type of robotics to help overcome this gap. Consensus control of robotic swarms is focused on, with a brief description of formation control and how it can be applied in the underwater setting. The basic concepts behind Particle Swarm Optimization, Ant Colony Optimization, Bees Algorithm and Heterogeneous Swarms has also been presented. The problems that are associated with communicating underwater are shown, with some possible solutions to this problem also being presented. Possible future work is described to conclude the paper.

Underwater swarm robotics : challenges and opportunities

Underwater swarm robotics today faces a series of challenges unique to its aquatic environment. This chapter explores some possible applications of underwater swarm robotics and its challenges. Those challenges include the environment itself, sensor types required, problems with communication and the difficulty in localisation. it notes the serious challenges in underwater communication is that radio communications is practically non-existent in the underwater realm. Localisation also becomes problematic due to the lack of radio waves as GPS cannot be used. it also looks at the platforms required by underwater robots and includes a possible low-cost platform. Also explored is a method of swarm robotics control known as consensus control. It shows possible solutions to the challenges and where swarm robotics may head.

Increased functionality of an underwater robotic manipulator

Research into underwater robotic applications is currently a growing field. There are many challenges involved in underwater robotics that are not present in other mediums, such as how the harsh environmental conditions that this environment invokes onto the robot and any equipment that is attached to the robot. In this paper an attachment to an underwater gripper is proposed that adds another Degree Of Freedom to the system, thus allowing the gripper to move along the belly of the robot. Adding this functionality to the gripper has many advantages, some of which involve the robot being able to easily pass a collected object to another robot with minimal interference. This attachment is constructed using 3D printed parts, a waterproofed servomotor and a leadscrew to provide linear motion to a commercial gripper.

HOG CHAINS AND MARK TWAINS: A STUDY OF LABOR HISTORY, ARCHAEOLOGY, AND INDUSTRIAL ETHNOGRAPHY OF THE STEAMBOAT ERA OF THE MONONGAHELA VALLEY 1811-1950

This dissertation examines a unique working class in the United States, the men and women who worked on the steamboats from the Industrial Revolution until the demise of steam-powered boats in the mid-20th century. The steamboat was the beginning of a technological system that was developed in America and used in such great numbers that it made the rapid population of the Trans-Appalachian West possible. The steamboat was forever romanticized by images of the antebellum South or the quick wit of Samuel Clemens and his sentimental book, Life on the Mississippi. The imagination swirls with thoughts of boats, bleach white, slowly churning the calm waters of some Spanish moss covered river. The reality of the boats and the experience of those who worked on them has been lost in this nostalgic vision. This research details the history of the western steamboat in the Monongahela Valley, the birthplace of the commercial steamboat industry. The first part of this dissertation examines the literature of authors in the field of labor history and Industrial Archaeology to place this work into the larger context of published literature. The second builds a framework for understanding the various eras that the steamboat went through both in terms of technological change, but also the change the workers experienced as their identity as a working class was being shaped. The third part details the excavations of two steamboat captains houses, those of Captain James Gormley and Captain Michael A. Cox. Both men represented a time in which the steamboat was in an era of transition. Excavations at their homes yield clues to their class status and how integrated they were in the local community. The fourth part of this study documents the oral histories of steamboat workers, both men and women, and their experience on the boats and on the river. Their rapidly declining population of those who lived and worked on the boats gives urgency for their lives to be documented. Finally, this study concludes with a synthesis of how worker identity solidified in the face of technological, socio-economic, and ideological change especially during their push for unionization and the introduction of the diesel towboat.

Archaeology and History at the Johannes Kolb Site–38DA75

This document describes the Johannes Kolb archaeological site in Darlington County, S.C.

Underwater survey of ichthyofauna of eastern Atlantic seamounts: Gettysburg and Ormond (Gorringe Bank)

Gettysburg and Ormond are seamounts belonging to the Gorringe Bank, which is located on the Europen-African plate boundary. Given the importance of these oceanic features for understanding marine biodiversity patterns, two surveys were carried out in 1998 (Gettysburg) and 1999 (Ormond) using diving, photography and video for species identification and abundance evaluation. Of the 9 fish species found at Gettysburg and 11 at Ormond, 6 were common to both sites and these included the dominant species: the oceanic and commercially important, Seriola rivoliana, and the coastal, typically Atlantic-Mediterranean Coris julis and Anthias anthias. The strong representation of coastal, demersal and Atlantic-Mediterranean species in the Gorringe Bank region and the presence of Abudefduf luridus, an endemic Macaronesian species, at Gettysburg suggests that the upper part of these seamounts may have acted and still act as “stepping stones” for the dispersal of coastal species.

A spatial data warehouse to predict lithic sources of tombs from South of Portugal: mixing geochemistry, petrology, cartography and archaeology in spatial analysis

MEGAGEO - Moving megaliths in the Neolithic is a project that intends to find the provenience of lithic materials in the construction of tombs. A multidisciplinary approach is carried out, with researchers from several of the knowledge fields involved. This work presents a spatial data warehouse specially developed for this project that comprises information from national archaeological databases, geographic and geological information and new geochemical and petrographic data obtained during the project. The use of the spatial data warehouse proved to be essential in the data analysis phase of the project. The Redondo Area is presented as a case study for the application of the spatial data warehouse to analyze the relations between geochemistry, geology and the tombs in this area.