Design, analysis and evaluation of sigma-delta based beamformers for medical ultrasound imaging applications

The inherent analogue nature of medical ultrasound signals in conjunction with the abundant merits provided by digital image acquisition, together with the increasing use of relatively simple front-end circuitries, have created considerable demand for single-bit  beamformers in digital ultrasound imaging systems. Furthermore, the increasing need to design lightweight ultrasound systems with low power consumption and low noise, provide ample justification for development and innovation in the use of single-bit  beamformers in ultrasound imaging systems. The overall aim of this research program is to investigate, establish, develop and confirm through a combination of theoretical analysis and detailed simulations, that utilize raw phantom data sets, suitable techniques for the design of simple-to-implement hardware efficient  digital ultrasound beamformers to address the requirements for 3D scanners with large channel counts, as well as portable and lightweight ultrasound scanners for point-of-care applications and intravascular imaging systems. In addition, the stability boundaries of higher-order High-Pass (HP) and Band-Pass (BP) Σ−Δ modulators for single- and dual- sinusoidal inputs are determined using quasi-linear modeling together with the describing-function method, to more accurately model the  modulator quantizer. The theoretical results are shown to be in good agreement with the simulation results for a variety of input amplitudes, bandwidths, and modulator orders. The proposed mathematical models of the quantizer will immensely help speed up the design of higher order HP and BP Σ−Δ modulators to be applicable for digital ultrasound beamformers. Finally, a user friendly design and performance evaluation tool for LP, BP and HP  modulators is developed. This toolbox, which uses various design methodologies and covers an assortment of  modulators topologies, is intended to accelerate the design process and evaluation of  modulators. This design tool is further developed to enable the design, analysis and evaluation of  beamformer structures including the noise analyses of the final B-scan images. Thus, this tool will allow researchers and practitioners to design and verify different reconstruction filters and analyze the results directly on the B-scan ultrasound images thereby saving considerable time and effort.

Reflections on conducting research on the ‘war on terror’: religious identity, subjectivity and emotions

In recent years there has been an increase in literature which has explored the insider/outsider position through ethnic identities. However, there remains a neglect of religious identities, even though it could be argued that religious identities have become increasingly important through being prominent in international issues such as the ‘war on terror’ and the Middle East conflict. Through drawing on the concept of subjectivity, I reflect on research I conducted on the impact of the ‘war on terror’ on British Muslims. I explore the space between the insider/outsider position demonstrating how my various subjectivities – the ‘non-Islamic appearance I’, the ‘Muslim I’, the ‘personal I’, the ‘exploring I’, the ‘Kashmiri I’ or the ‘Pakistani I’, the ‘status I’ and the ‘outsider I’ – assisted in establishing trust, openness and commonality. I conclude by demonstrating how the ‘emotional I’ allowed me to manage my own emotions and participants emotions.

Media Research and Psychoanalysis: A Suggestion

This short commentary outlines psychoanalysis as a theory and method and its potential value to media research. Following Dahlgren (2013), it is suggested that psychoanalysis may enrich the field because it may offer a complex theory of the human subject, as well as methodological means of doing justice to the richness, ambivalence and contradictions of human experience. The psychoanalytic technique of free association and how it has been adapted in social research (Hollway and Jefferson 2000) is suggested as a means to open up subjective modes of expression and thinking – in researchers and research participants alike – that lie beyond rationality and conscious agency.

Evaluating the Business Impact of Social Science: a report to the ESRC

This report presents the main findings from a project entitled ‘Evaluating the Business Impact of Social Science', commissioned by the Economic and Social Research Council (ESRC) and undertaken by a team of researchers from the University of Hull. In brief, the project involved an examination of the processes through which social science research and related activities impact upon business (defined broadly to incorporate large and small private sector businesses as well as social enterprises, but excluding public sector organisations) in relation to three of the UK’s leading business/management schools that have received significant amounts of ESRC funding in recent years: Cardiff Business School, Lancaster University Management School, and Warwick Business School

Cruise Speed Reduction for Ground Delay Programs: A Case Study for San Francisco International Airport Arrivals

Ground Delay Programs (GDP) are sometimes cancelled before their initial planned duration and for this reason aircraft are delayed when it is no longer needed. Recovering this delay usually leads to extra fuel consumption, since the aircraft will typically depart after having absorbed on ground their assigned delay and, therefore, they will need to cruise at more fuel consuming speeds. Past research has proposed speed reduction strategy aiming at splitting the GDP-assigned delay between ground and airborne delay, while using the same fuel as in nominal conditions. Being airborne earlier, an aircraft can speed up to nominal cruise speed and recover part of the GDP delay without incurring extra fuel consumption if the GDP is cancelled earlier than planned. In this paper, all GDP initiatives that occurred in San Francisco International Airport during 2006 are studied and characterised by a K-means algorithm into three different clusters. The centroids for these three clusters have been used to simulate three different GDPs at the airport by using a realistic set of inbound traffic and the Future Air Traffic Management Concepts Evaluation Tool (FACET). The amount of delay that can be recovered using this cruise speed reduction technique, as a function of the GDP cancellation time, has been computed and compared with the delay recovered with the current concept of operations. Simulations have been conducted in calm wind situation and without considering a radius of exemption. Results indicate that when aircraft depart early and fly at the slower speed they can recover additional delays, compared to current operations where all delays are absorbed prior to take-off, in the event the GDP cancels early. There is a variability of extra delay recovered, being more significant, in relative terms, for those GDPs with a relatively low amount of demand exceeding the airport capacity.

Queer youth, Facebook and faith: Facebook methodologies and online identities

‘Making space for queer-identifying religious youth’ (2011–2013) is an Economic and Social Research Council (ESRC)-funded project, which seeks to shed light on youth cultures, queer community and religiosity. While non-heterosexuality is often associated with secularism, and some sources cast religion as automatically negative or harmful to the realisation of lesbian, gay, bisexual and transgender (LGBT) identity (or ‘coming out’), we explore how queer Christian youth negotiate sexual–religious identities. There is a dearth of studies on queer religious youth, yet an emerging and continuing interest in the role of digital technologies for the identities of young people. Based on interviews with 38 LGBT, ‘religious’ young people, this article examines Facebook, as well as wider social networking sites and the online environment and communities. Engaging with the key concept of ‘online embodiment’, this article takes a closer analysis of embodiment, emotion and temporality to approach the role of Facebook in the lives of queer religious youth. Furthermore, it explores the methodological dilemmas evoked by the presence of Facebook in qualitative research with specific groups of young people.

Democracy Matters: Lessons from the 2015 Citizens' Assemblies on English Devolution

The Citizens’ Assembly pilots on local democracy and devolution were the first of their kind in the United Kingdom. Organised by Democracy Matters — an alliance of university researchers and civil society organisations led by Professor Matthew Flinders — and funded by the UK’s Economic and Social Research Council, the Assemblies took place in Southampton and Sheffield towards the end of 2015.

Third-mission policy goals and incentives from performance-based funding: Are they aligned?

In competitive knowledge-based economies, policymakers recognize the importance of universities’ engagement in third mission activities. This article investigates how a specific policy approach to encourage third mission engagement—the use of performance-based funding to reward universities’ success in this domain—aligns with the broader goals of third mission policy. Considering the case of the UK, the first country to have implemented a system of this kind, we analyse how the system has come into being and how it has evolved, and we discuss whether its implementation is likely to encourage universities to behave in ways that are aligned with the goals of third mission policy, as outlined in government documents. We argue that the system encourages universities to focus on a narrow range of income-producing third mission activities, and this is not well aligned with the policy goal to support a complex innovation ecosystem comprising universities with different third mission objectives and strategies. The article concludes by proposing possible avenues for achieving greater alignment between incentives and policy goals.

Design and implementation of generalized topologies of time-interleaved variable bandpass Σ−Δ modulators

In this thesis, novel analog-to-digital and digital-to-analog generalized time-interleaved variable bandpass sigma-delta modulators are designed, analysed, evaluated and implemented that are suitable for high performance data conversion for a broad-spectrum of applications. These generalized time-interleaved variable bandpass sigma-delta modulators can perform noise-shaping for any centre frequency from DC to Nyquist. The proposed topologies are well-suited for Butterworth, Chebyshev, inverse-Chebyshev and elliptical filters, where designers have the flexibility of specifying the centre frequency, bandwidth as well as the passband and stopband attenuation parameters. The application of the time-interleaving approach, in combination with these bandpass loop-filters, not only overcomes the limitations that are associated with conventional and mid-band resonator-based bandpass sigma-delta modulators, but also offers an elegant means to increase the conversion bandwidth, thereby relaxing the need to use faster or higher-order sigma-delta modulators. A step-by-step design technique has been developed for the design of time-interleaved variable bandpass sigma-delta modulators. Using this technique, an assortment of lower- and higher-order single- and multi-path generalized A/D variable bandpass sigma-delta modulators were designed, evaluated and compared in terms of their signal-to-noise ratios, hardware complexity, stability, tonality and sensitivity for ideal and non-ideal topologies. Extensive behavioural-level simulations verified that one of the proposed topologies not only used fewer coefficients but also exhibited greater robustness to non-idealties. Furthermore, second-, fourth- and sixth-order single- and multi-path digital variable bandpass digital sigma-delta modulators are designed using this technique. The mathematical modelling and evaluation of tones caused by the finite wordlengths of these digital multi-path sigmadelta modulators, when excited by sinusoidal input signals, are also derived from first principles and verified using simulation and experimental results. The fourth-order digital variable-band sigma-delta modulator topologies are implemented in VHDL and synthesized on Xilinx® SpartanTM-3 Development Kit using fixed-point arithmetic. Circuit outputs were taken via RS232 connection provided on the FPGA board and evaluated using MATLAB routines developed by the author. These routines included the decimation process as well. The experiments undertaken by the author further validated the design methodology presented in the work. In addition, a novel tunable and reconfigurable second-order variable bandpass sigma-delta modulator has been designed and evaluated at the behavioural-level. This topology offers a flexible set of choices for designers and can operate either in single- or dual-mode enabling multi-band implementations on a single digital variable bandpass sigma-delta modulator. This work is also supported by a novel user-friendly design and evaluation tool that has been developed in MATLAB/Simulink that can speed-up the design, evaluation and comparison of analog and digital single-stage and time-interleaved variable bandpass sigma-delta modulators. This tool enables the user to specify the conversion type, topology, loop-filter type, path number and oversampling ratio.