The drag of a body moving transversely in a confined stratified fluid

The slow motion of a body through a stratified fluid bounded laterally by insulating walls is studied for both large and small Peclet number. The Taylor column and its associated boundary and shear layers are very different from the analogous problem in a rotating fluid. In particular, the large Peclet number problem is non-linear and exhibits mixing of statically unstable fluid layers, and hence the drag is order one; whereas the small Peclet number flow is everywhere stable, and the drag is of the order of the Peclet number

Sequential Complexity as a Descriptor for Musical Similarity

We propose string compressibility as a descriptor of temporal structure in audio, for the purpose of determining musical similarity. Our descriptors are based on computing track-wise compression rates of quantised audio features, using multiple temporal resolutions and quantisation granularities. To verify that our descriptors capture musically relevant information, we incorporate our descriptors into similarity rating prediction and song year prediction tasks. We base our evaluation on a dataset of 15500 track excerpts of Western popular music, for which we obtain 7800 web-sourced pairwise similarity ratings. To assess the agreement among similarity ratings, we perform an evaluation under controlled conditions, obtaining a rank correlation of 0.33 between intersected sets of ratings. Combined with bag-of-features descriptors, we obtain performance gains of 31.1% and 10.9% for similarity rating prediction and song year prediction. For both tasks, analysis of selected descriptors reveals that representing features at multiple time scales benefits prediction accuracy.Comment: 13 pages, 9 figures, 8 tables. Accepted versio

Attitudes towards shoplifting: a preliminary cross-cultural study of consumers

Shoplifting has a substantial impact on retailers, consumers and wider society, yet we know very little about people‟s attitudes towards this behaviour, especially from a non-Western perspective. A better understanding of consumer misbehaviour in Arabic countries would therefore be of particular interest as such societies represent a new market for global retailers. The aim of this paper, therefore, is to explore the initial results of consumers‟ attitudes towards shoplifting from a cross-cultural perspective. Preliminary analysis of 529 questionnaire responses from UK, US and Libyan consumers finds that attitudes towards shoplifting are broadly similar despite the different cultural and retail contexts. However, on closer inspection these findings suggest interesting disparities between the countries in relation to attitudes towards the consequences of shoplifting, the impact it has on the social networks of the perpetrator and whether the demographics of the shoplifter play a role in the decision to punish the offender

GA tuning of pitch controller for small scale MAVs

The paper presents the application of intelligent tuning methods for the control of a prototype MAV in order to address problems associated with bandwidth limited actuators and gust alleviation. Specifically, as a proof of concept, the investigation is focused on the pitch control of a MAV. The work is supported by experimental results from wind tunnel testing that shows the merits of the use of Genetic Algorithm (GA) tuning techniques compared to classical, empirical tuning methodologies. To provide a measure of relative merit, the controller responses are evaluated using the ITAE performance index. In this way, the proposed method is shown to induce far superior dynamic performance compared to traditional approaches

Seeing social enterprise through the theoretical conceptualisation of ethical capital

Objectives: Current conceptualisations of social enterprise fail to fully satisfy an understanding of the movement. A focus on the economic implies a business model where deep tensions lie. A focus on social capital offers a different frame of reference, yet both these conceptualisations fail to fully identify the phenomena that is social enterprise. The objective of this paper seeks to fill that gap. Ethical capital is offered here as the missing conceptualisation in the field of social enterprise. Prior work: Pearce (2003) describes social enterprises as part of the third system, closer to the first system (private business), than the second system (public provision), yet primarily social and secondly a business. Social Enterprises are described as trading organisations in a market (Pearce 2003). A focus and operationalisation for social enterprises to be ‘business-like’ and ‘entrepreneurial’ is well documented (Leadbeater 1997; Dees 1998; Nicholls 2006b). Approach: Yet, if as part of the third sector, social enterprises are as Dart (2004) suggests; ‘blurring the boundaries between non-profit and profit’, but what blurs? What is compromised? What exactly is lost (or gained)? What challenges are there for social enterprises? And is a managerialist ideology taking precedence over the social? This paper provides a conceptual paper that seeks to outline the arguments on the table and develop an ethical capital conceptualisation of social enterprise. Results: This paper very much aims at starting the process of intellectual debate about the notion of ethical capital in social enterprises. The conclusions of this paper outline further research questions that need to be addressed in order to fully develop this concept. Implications: The current ideology of the neo-classical economic paradigm it is argued in the paper pursues interests towards the self and towards the erosion of the moral basis of association. The outcome leaves society with a problem of low ethical virtue - the implications of this paper are that social enterprises maximise ethical virtue beyond any other form of organisation and as such hold great value beyond their missions and values. Value: This paper offers great value in the understanding of social enterprise through fresh insight into the conceptualisation. A critical perspective to the current literature is taken and discussed but though the introduction of ethical capital this paper takes our understanding of the value of the sector into another light, providing practitioners, business support agencies and academics alike with a different level of conceptualisation that has not been explored before.</p

A back to back multilevel converter for driving low inductance brushless AC machines

Traditionally, multilevel converters are utilised in medium voltage applications, allowing the DC-link voltage to exceed the switch maximum blocking voltage. Here, their application to control high- efficiency brushless permanent magnet synchronous machines exhibiting low phase inductance is explored, the relative advantages being shown to include reduced current ripple and improved harmonic spectrum. A cost benefit analysis is included along with experimental results from a prototype 5-level back-to-back converter

Modelling and regulation of dual-output LCLC resonant converters

The analysis, design and control of 4th-order LCLC voltage-output series-parallel resonant converters (SPRCs) for the provision of multiple regulated outputs, is described. Specifically, state-variable concepts are employed and new analysis techniques are developed to establish operating mode boundaries with which to describe the internal behaviour of a dual-output resonant converter topology. The designer is guided through the most important criteria for realising a satisfactory converter, and the impact of parameter choices on performance is explored. Predictions from the resulting models are compared with those obtained from SPICE simulations and measurements from a prototype power supply under closed loop control

A cascaded H-bridge BLDC drive incorporating battery management

A multilevel BLDC drive is proposed using cascaded H-bridges with isolated sources to provide superior output waveforms and reduced current ripple whilst incorporating observer based SoC estimation. Energy management, based on SoC, is incorporated to improve battery performance, reduce variation between cells and to control charge/discharge profiles

Rapid steady-state analysis of CLL resonant power converters

Cyclic averaging techniques are applied to the CLL resonant power converter to provide steady-state converter characteristics for rapid stress analysis. This is shown to facilitate the determination of mode duties and initial conditions through knowledge of the operational modes of the rectifier at various operating frequencies. Comparisons are made with FMA-based cyclic analyses, and Spice simulations, that show, respectively, improved accuracy and vastly improved execution speeds