Characterisation of long-range horizontal performance of underwater acoustic communication

Underwater acoustic communication is a rapidly progressing field of technology, largely due to recent advances in low cost and power efficient digital signal processors. Unfortunately, the unpredictable and time varying physical properties of the underwater acoustic channel reduce communication reliability over long ranges. This study sought to characterise the performance of horizontal underwater acoustic data communication in various scenarios with particular application to subsea monitoring and control systems.To fulfil the experimental needs, two custom-built high frequency ambient noise recorder and modem control units were developed to operate with commercial underwater acoustic modems. Additionally, an underwater acoustic communication simulator based on the Bellhop propagation model was developed for Matlab, capable of producing performance predictions in both spatial and temporal studies. A series of short-term trials were conducted to determine the limitations of modem performance over different ranges. These trials included shallow water studies off the coast of Perth, Western Australia (D < 30 m), and a French deep water trial (D ≤ 1000 m) which used stand-alone modems. Experimental findings were compared to predictions obtained using two-dimensional range-depth performance simulations.A long-term investigation of the environmental influences on modem reliability was carried out off the coast of Perth in approximately 100 m of water. This involved simultaneously collecting environmental and modem performance data for over 16 days. The signal to noise ratio remained high for the duration of the trial so modem performance fluctuations could be attributed to changes in channel propagation. Using multiple linear regression, the measured environmental parameters were correlated with the observed modem performance and their contributions to an overall fitting curve were calculated. It was determined that the sound speed profile, in addition to the sea surface roughness, contributed strongly to the fitting curve, with a weaker contribution from the measured signal to noise ratio. This result was confirmed by performing temporal simulations which incorporated more detailed time-dependant environmental parameters. By progressively adding more parameters to the simulator including ambient noise, wave height and the sound speed profile, simulations provided more accurate predictions of the observed performanceOverall, the horizontal performance of underwater acoustic communication was characterised in several scenarios from a series of experimental and numerical investigations. Additionally, the developed simulator was shown to be an effective and flexible tool for predicting the performance of an underwater acoustic communication system. The results and tools discussed in this thesis provide an extensive investigation into the factors influencing horizontal underwater acoustic communication. The analysis demonstrates that whilst underwater acoustic communication can be effective, it is not yet a viable alternative to cabled telemetry for long-range subsea monitoring and control applications, where reliability is crucial. Underwater acoustic communication would best be suited as a non-critical or backup method for continuous monitoring systems until channel prediction and equalisation techniques are further refined

Designing Playful Systems

Play is a common, yet elusive phenomenon. Many definitions of play and explanations for its existence have been brought forward in various disciplines such as psychology, anthropology, ethology and in the humanities. As an activity apparently serving no other purpose than itself, play can be simply considered a pleasant pastime. Yet its equation with fun has been challenged by artists and scholars alike. Being in a playful state does not warrant extrinsic motivation or being conscious of an external purpose. However, play creates meaning, and scientists are pursuing functional explanations for it. These conflicting observations are contributing to the ambiguity of play and they raise questions about the limits of complexity that present discourses are able to reflect. This thesis presents a comprehensive, transdisciplinary approach to describe and understand play, based on systems-theory, constructivism, cybernetics and practical exploration. Observing play in this way involves theoretical analysis, reflection and critique as well as the practice of design, development and artistic exposition. By constructing, re-contextualising and discussing eight of my own projects, I explore the distinction between theory and practice through which playful systems emerge. Central to my methodology is the concept of distinctions as a fundamental method of observation. It is introduced itself as a distinction and then applied throughout, in order to describe and discuss phenomena of play from a wide range of different perspectives. This includes paradoxical, first-person and conflicting accounts and it enables discourses that cross disciplinary boundaries. In summary, the three interrelated contributions to knowledge in my research project are: I contribute to the emerging field of game studies through a comprehensive systems-theoretical description on play. I also provide a methodology in which theory and practice inform each other through mutual observation, construction, reflection and critical evaluation. Finally, I present eight projects, including a playful system developed in a speculative approach that I call anthroponeutral design. These results represent a novel transdisciplinary perspective on play that offers new opportunities for further research

Diversity, Dynamics and Domestic Energy Demand:A Study of Variation in Cooking, Comfort and Computing

This thesis contributes to an understanding of domestic energy demand and its basis in social practice. To date, energy consumption and everyday life have mostly been characterised and connected, if at all, through general trends. Yet attention to diversity within everyday practices, and to the diverse relations to energy consumption, is crucial to the development of nuanced, practice-specific understandings that could inform demand reduction policies. By investigating variations in, and the nature of connections between, energy consumption and practice this thesis reveals and compares the distinctive dynamics of demand in cooking, comfort and computer-use. The method combines qualitative interviews and energy measurement in a small-scale, detailed study at a site where sources of variation are limited and can thus be compared: student halls of residence. This shows that frequency and type of meal are important in cooking-related energy consumption. The latter reflects diversification in the practice of cooking, which is also linked to a general decline in associated energy use. With respect to thermal comfort, indoor climatic conditions are adjusted in relation to clothing but the operation and energy consumption of heating systems are largely detached from other activities of daily life, even whilst indirectly enabling them. This presents an opportunity for thermal expectations to escalate and converge. Finally, substantial variations in energy use were observed in the diverse and inter-connected practices, services and hardware relating to information, communication and entertainment. This suggests that macro patterns of energy consumption may not simply be increasing but diverging. In analysing these findings, the thesis discusses the conceptualisation of variation within social practices, the varied roles of materials and the notion of ‘service’ in analysing how practices connect, vary and change. It concludes by outlining new lines of investigation at the intersections of energy, material culture and social practice research

Development of a dynamic underwater acoustic communication channel simulator with configurable sea surface parameters to explore time-varying signal distortion

A wide-band phase-coherent multi-path underwater acoustic channel simulation is developed using an approximate quantitative model of the acoustic wave response to a time-varying three-dimensional rough surface. It has been demonstrated over transmission ranges from 100 m to 8 km by experimental channel probing and comparable synthetic replication of the channel probing through the simulated channel, that the simulation is capable of reproducing fine-time-scale Doppler and delay distortions consistent with those generated in real shallow channels

The intertextual presence of cyberpunk in cultural and subcultural accounts of science and technology

This thesis looks at the relationship between cyberpunk science fiction and those sections of cyberculture most interested in the computer networks. This relationship is investigated in order to understand the nature of a recent cultural formation developed around the use of computer-mediated communications (CMC). By means of a textual analysis of pamphlets, books, articles, and electronic discussion groups, the thesis establishes the existence of an articulate cultural consensus among groups/theorists/practitioners involved in the politics of CMC. This consensus reveals a consistent opposition between the technology of industrialisation, which is characterised by uniformity and hierarchy, and a new technology defined in terms of diversity, and autonomy. The thesis argues that the political discourse of cyberculture is structured by an opposition between 'good' and 'bad' uses of technology. CMC can be used to establish a regime of decentralised surveillance or to promote a more democratic political participation. In the narratives elaborated by cyberculture, the technology of CMC is represented as being intrinsically democratic. Cyberculture also suggests that advanced technological skills can be used to counteract the most repressive uses of technology and to foster its more intrinsic progressive possibilities.These narratives are explored through the statements expressed by a series of groups, who are particularly active in relation to technology. The thesis investigates the ways in which Internet communities responded to the first laws which aimed to regulate the Internet. These were proposed by the Clinton administration in the US. The 'posthuman philosophy', a current of thought which believes in evolving humans into posthumans by using advanced technology, is also analysed in the accounts, offered by the Extropy group and the magazine Mondo 2000. The notion that the technology of CMC is inherently self-regulating and democratic is criticised in relation to 'cyberevolutionism', a popular discourse which sees the Internet as a self-regulating organism. Finally, the thesis argues that gender is the subject of much controversy in Internet culture

Collaborating with the Behaving Machine: simple adaptive dynamical systems for generative and interactive music

Situated at the intersection of interactive computer music and generative art, this thesis is inspired by research in Artificial Life and Autonomous Robotics and applies some of the principles and methods of these fields in a practical music context. As such the project points toward a paradigm for computer music research and performance which comple- ments current mainstream approaches and develops upon existing creative applications of Artificial Life research. Many artists have adopted engineering techniques from the field of Artificial Life research as they seem to support a richer interactive experience with computers than is often achieved in digital interactive art. Moreover, the low level aspects of life which the research programme aims to model are often evident in these artistic appropriations in the form of bizarre and abstract but curiously familiar digital forms that somehow, despite their silicon make-up, appear to accord with biological convention. The initial aesthetic motivation for this project was very personal and stemmed from interests in adaptive systems and improvisation and a desire to unite the two. In sim- ple terms, I wanted to invite these synthetic critters up on stage and play with them. There has been some similar research in the musical domain, but this has focused on a very small selection of specific models and techniques which have been predominantly applied as compositional tools rather than for use in live generative music. This thesis considers the advantages of the Alife approach for contemporary computer musicians and offers specific examples of simple adaptive systems as components for both compo- sitional and performance tools. These models have been implemented in a range of generative and interactive works which are described here. These include generative sound installations, interactive instal- lations and a performance system for collaborative man-machine improvisation. Public response at exhibitions and concerts suggests that the approach taken here holds much promise

Grave Reminders

From ca. 1600 – 1000 BC, builders across southern Greece crafted thousands of rock-cut chamber tombs similar to earlier and contemporary ‘beehive’ tholos tombs. Both tomb styles were designed with multiple uses in mind, filling with the remains of funerals forgotten over generations of reuse. In rare cases, the tombs were used once or seemingly not at all, cleaned thoroughly or sealed and abandoned entirely. Rather than focus on the missing or muddled record of funeral and post-funeral activities, this book re-examines Mycenaean tomb architecture and the decisions that guided it. From minimalistic to monumental, builders designed tombs with forethought to how commissioners and witnesses would react and remember them. Patterns suggest that memories of what tombs should look like heavily influenced new construction toward recurring shapes and appropriate scales. The wider debates over cost from ‘architectural energetics’ and perception in Aegean mortuary behaviour are thus revisited. Both can find common purpose in labour measured through a relative index and collective memory – how labourers and patrons saw their work. That metric for comparison lies within a median standard: in this instance, tombs expressed in terms of correlative shape and simple labour investment of the earth and rock moved to create them. This was accomplished here through photogrammetric modelling of 94 multi-use tombs in Achaea and Attica, verifying a cost-effective alternative for local authorities warding off information loss through site destruction from looting and earthquakes. Since most labour models suggest the tombs were not burdensome, commissioners held extravagant building in check by weighing the social risks and rewards of standing out from the crowd

Risk, resilience and responsibilisation: gendered participation and empowerment in informal settlements of Metro Cebu, the Philippines

The Philippines is one of the most disaster-affected countries in the world and considered especially vulnerable to the adverse impacts of climate change. As the economic, social and environmental consequences of these phenomena become more pronounced across the archipelago, disaster risk reduction and management (DRRM) and climate change adaptation have unsurprisingly gained more attention in national and local policies and development agendas. Within this terrain, community-based DRRM (CBDRRM) has emerged as a core orthodoxy informing intervention, particularly in the context of low-income informal settlements which are among the most exposed and least able to protect themselves and recover from such events. In Metro Cebu, calls for creating a more ‘sustainable’ and ‘resilient’ city are also placing urban poor communities in an increasingly precarious position, with those living in areas classed as ‘danger zones’ simultaneously facing intensified pressures of displacement in the name of risk management. Amidst this context of multiple and overlapping forms of risk and insecurity, community organising among informal settlers has become a critical mechanism for building local capacities and resisting different socio-political and environmental threats. Largely mobilised and driven by women, these grassroots entities, often in the shape of homeowner associations, are fundamental to collective contestations of policies and practices that adversely or unfairly affect the urban poor of Cebu, while also serving as strategic sites for advancing claims on public resources and local risk management activities. This thesis interrogates the gendered politics of risk and community organising among informal settlers in Metro Cebu. Drawing on the perspectives and experiences of women and men living in areas classed as danger zones, I argue that encounters with risk (and disaster) constitute an ‘everyday’ rather than ‘exceptional’ reality for informal settlers, and that the siloed focus on large-scale catastrophic events obscures these gendered realities and therein limits the efficacy of CBDRRM initiatives. Relatedly, I contend that the language of ‘disasters’ and ‘climate change’ being endorsed and propagated by the Philippine state depoliticises discussions of risk by concealing the socio-political and structural drivers of vulnerability and deflecting attention away from the power configurations and actors complicit in the production of risk. In fact, my analysis of how DRRM features within broader urban development processes in the metropole showcases how ‘disaster resilience’ and ‘pro-poor development’ are being mobilised to serve elite commercial interests and legitimise the removal of slums