On various low-hardware-complexity LMS algorithms for adaptive I/Q correction in quadrature receivers

In this paper, the performance and convergence time comparisons of various low-complexity LMS algorithms used for the coefficient update of adaptive I/Q corrector for quadrature receivers are presented. We choose the optimum LMS algorithm suitable for low complexity, high performance and high order QAM and PSK constellations. What is more, influence of the finite bit precision on VLSI implementation of such algorithms is explored through extensive simulations and optimum wordlengths established.

A low-complexity self-calibrating adaptive quadrature receiver

In this paper digital part of a self-calibrating quadrature-receiver is described, containing a digital calibration-engine. The blind source-separation-based calibration-engine eliminates the RF-impairments in real-time hence improving the receiver's performance without the need for test/pilot tones, trimming or use of power-hungry discrete components. Furthermore, an efficient time-multiplexed calibration-engine architecture is proposed and implemented on an FPGA utilising a reduced-range multiplier structure. The use of reduced-range multipliers results in substantial reduction of area as well as power consumption without a compromise in performance when compared with an efficiently designed general purpose multiplier. The performance of the calibration-engine does not depend on the modulation format or the constellation size of the received signal; hence it can be easily integrated into the digital signal processing paths of any receiver.

A low complexity cross-correlation interference mitigation technique for GNSS

The finite length Gold codes used in satellite navigation systems limit their dynamic range, resulting in the introduction of unwanted peaks that can mask out signals of interest. In this paper, a novel cross-correlation interference mitigation technique dealing with this issue is introduced. A brief overview of the multiple access interference problem inherent in satellite navigation systems using the code division multiple access technique is followed by the details of the proposed method. Simulation case studies and analyses of the results detailing weak signal scenarios, carried out entirely using the Global Navigation System Scope, are presented. A comparison of the results is given in the conclusions section along with remarks on the performance of the proposed method and future work to be carried out.

Complexity theory and tourism policy research

This paper investigates applications of complexity theory in the social sphere and considers its potential contribution to enhance understanding of tourism policy making. Five concepts are identified to explore complex social circumstances and human interactions that influence policy. Social applications of complexity suggest a move towards localised and deeper studies to explore the dynamics of policy enactment in context. It suggests complexity theory might be used as a thinking tool to enable a more holistic approach to policy analysis and investigate policy in its context, considering interactions between different policies/programmes, and the implications of human agency.

A method for analysing operational complexity in supply chains

This paper proposes a method for analysing the operational complexity in supply chains by using an entropic measure based on information theory. The proposed approach estimates the operational complexity at each stage of the supply chain and analyses the changes between stages. In this paper a stage is identified by the exchange of data and/or material. Through analysis the method identifies the stages where the operational complexity is both generated and propagated (exported, imported, generated or absorbed). Central to the method is the identification of a reference point within the supply chain. This is where the operational complexity is at a local minimum along the data transfer stages. Such a point can be thought of as a ‘sink’ for turbulence generated in the supply chain. Where it exists, it has the merit of stabilising the supply chain by attenuating uncertainty. However, the location of the reference point is also a matter of choice. If the preferred location is other than the current one, this is a trigger for management action. The analysis can help decide appropriate remedial action. More generally, the approach can assist logistics management by highlighting problem areas. An industrial application is presented to demonstrate the applicability of the method.

(un)childhood: performing the voices and times of childhood through relational video-making

This practice-based PhD is comprised of two interrelated elements: (i) ‘(un)childhood’, a 53’ video-essay shown on two screens; and (ii) a 58286 word written thesis. The project, which is contextualised within the tradition of artists working with their own children on time-based art projects, explores a new approach to timebased artistic work about childhood. While Stan Brakhage (1933-2003), Ernie Gher (1943-), Erik Bullot (1963-) and Mary Kelly (1941-) all documented, photographed and filmed their children over a period of years to produce art projects (experimental films and a time-based installation), these projects were implicitly underpinned by a construction of childhood in which children, shown as they grow, represent the abstract primitive subject. The current project challenges the convention of representing children entirely from the adult’s point of view, as aesthetic objects without a voice, as well as through the artist’s chronological approach to time. Instead, this project focuses on the relational joining of the child’s and adult’s points of view. The artist worked on a video project with her own son over a four-and-a-half year period (between the ages of 5 and 10) through which she developed her ‘relational video-making’ methodology. The video-essay (un)childhood performs the relational voices of childhood as resulting from the verbal interactions of both children and adults. The non-chronological nature of(un)childhood offers an alternative to the linear-temporal approach to the representation of childhood. Through montage and a number of literal allusions to time in its dialogue, (un)childhood performs the relational times of childhood by combining children’s lives in the present with the temporal dimensions that have traditionally constructed childhood: past, future and timeless.

Reflections Upon the Experience of Longitudinal Research into Cultural Event Production in a Developing Destination

Longitudinal studies have the capacity to provide more nuanced explanations of tourism and event phenomena, taking account of complexity, change and context. This paper is a self-reflexive, methodological study of research practice. It investigates my experience of engaging with cultural event producers in an emerging destination over a seven-year period. Focussing on my research journey, it considers the social and relational dynamics associated with longitudinal research. Reciprocal relations and co-production of cultural events reveal nuanced information and expose fluid relationships and networks. Long-term engagement uncovers evolving practices and develops understanding of event processes embedded within their wider context.

Low Complexity All-Pass Based Polyphase Decimation Filters for ECG Monitoring

This paper presents a low complexity high efficiency decimation filter which can be employed in EletroCardioGram (ECG) acquisition systems. The decimation filter with a decimation ratio of 128 works along with a third order sigma delta modulator. It is designed in four stages to reduce cost and power consumption. The work reported here provides an efficient approach for the decimation process for high resolution biomedical data conversion applications by employing low complexity two-path all-pass based decimation filters. The performance of the proposed decimation chain was validated by using the MIT-BIH arrhythmia database and comparative simulations were conducted with the state of the art.

Data Visualisation Does Political Things

In this paper I advance the theory of critical communication design by exploring the politics of data, information and knowledge visualisation in three bodies of work. Data reflects power relations, special interests and ideologies that determine which data is collected, what data is used and how it is used. In a review of Max Roser’s Our World in Data, I develop the concepts of digital positivism, datawash and darkdata. Looking at the Climaps by Emaps project, I describe how knowledge visualisation can support integrated learning on complex problems and nurture relational perception. Finally, I present my own Mapping Climate Communication project and explain how I used discourse mapping to develop the concept of discursive confusion and illustrate contradictions in this politicised area. Critical approaches to information visualisation reject reductive methods in favour of more nuanced ways of presenting information that acknowledge complexity and the political dimension on issues of controversy.

Dynamic Network Mechanisms of Relational Integration

A prominent hypothesis states that specialized neural modules within the human lateral frontopolar cortices (LFPCs) support “relational integration” (RI), the solving of complex problems using inter-related rules. However, it has been proposed that LFPC activity during RI could reflect the recruitment of additional “domain-general” resources when processing more difficult problems in general as opposed to RI specifi- cally. Moreover, theoretical research with computational models has demonstrated that RI may be supported by dynamic processes that occur throughout distributed networks of brain regions as opposed to within a discrete computational module. Here, we present fMRI findings from a novel deductive reasoning paradigm that controls for general difficulty while manipulating RI demands. In accordance with the domain- general perspective, we observe an increase in frontoparietal activation during challenging problems in general as opposed to RI specifically. Nonetheless, when examining frontoparietal activity using analyses of phase synchrony and psychophysiological interactions, we observe increased network connectivity during RI alone. Moreover, dynamic causal modeling with Bayesian model selection identifies the LFPC as the effective connectivity source. Based on these results, we propose that during RI an increase in network connectivity and a decrease in network metastability allows rules that are coded throughout working memory systems to be dynamically bound. This change in connectivity state is top-down propagated via a hierarchical system of domain-general networks with the LFPC at the apex. In this manner, the functional network perspective reconciles key propositions of the globalist, modular, and computational accounts of RI within a single unified framework.