Orbit period modulation for relative motion using continuous low thrust in the two-body and restricted three-body problems

This paper presents rich new families of relative orbits for spacecraft formation flight generated through the application of continuous thrust with only minimal intervention into the dynamics of the problem. Such simplicity facilitates implementation for small, low-cost spacecraft with only position state feedback, and yet permits interesting and novel relative orbits in both two- and three-body systems with potential future applications in space-based interferometry, hyperspectral sensing, and on-orbit inspection. Position feedback is used to modify the natural frequencies of the linearised relative dynamics through direct manipulation of the system eigenvalues, producing new families of stable relative orbits. Specifically, in the Hill–Clohessy–Wiltshire frame, simple adaptations of the linearised dynamics are used to produce a circular relative orbit, frequency-modulated out-of-plane motion, and a novel doubly periodic cylindrical relative trajectory for the purposes of on-orbit inspection. Within the circular restricted three-body problem, a similar minimal approach with position feedback is used to generate new families of stable, frequency-modulated relative orbits in the vicinity of a Lagrange point, culminating in the derivation of the gain requirements for synchronisation of the in-plane and out-of-plane frequencies to yield a singly periodic tilted elliptical relative orbit with potential use as a Lunar far-side communications relay. The Δv requirements for the cylindrical relative orbit and singly periodic Lagrange point orbit are analysed, and it is shown that these requirements are modest and feasible for existing low-thrust propulsion technology

'Laddishness' as a Self-worth Protection Strategy.

'Laddishness' is central to the current discourse on boys' 'underachievement', with 'laddish' behaviours being seen by many people as an impediment to the progress of some boys in school. The article attempts to demonstrate how self-worth theory may complement and extend our understandings of 'laddish' behaviours, which are currently informed by theories of masculinities. More specifically, it is argued that it may be the case that for some secondary school boys, the construct of 'laddishness' acts as a self-worth protection strategy - protecting self-worth both from the implications of a lack of ability and from the implications of being seen to be feminine. The argument is developed by comparing characteristics of key self-worth protection or self-handicapping strategies with the behaviours reported by teachers, pupils and researchers to be characteristics of 'laddish' behaviour

Analysing the language of war monuments

This paper seeks an approach for a systematic analysis of the semiotic resources used by the designers of British World War 1 monuments. Semiotic studies of monuments have emphasised on the one hand factors from outside the' text', in other words contextual social and political factors that lead to design decisions, and on the other hand factors within the text, as being maximally important for this - the latter characterising such visual communication, like language, as a system or code. The paper uses an assessment of an example of the latter, O'Toole's functional analysis (1994) of sculptures, using a number of theories of the visual to draw out its limitations and point to a number of characteristics of visual communication that would need to be considered in order to carry out a satisfactory analysis.Peer reviewe