Optimum design of composite laminates with thermal effects

An analytical approach to determine an optimum laminate for a variety of thermal and mechanical loading combinations is presented. The analysis is performed for a linear elastic material under static mechanical and uniform thermal loadings. The problem is restricted to a unit width and length laminate with angle orientations resulting in an orthotropic, symmetric, and balanced configuration. An objective function defining total strain energy, is formulated and an optimum laminate design determined subject to constraints on stiffness, average coefficient of thermal expansion, and strength. The objective function is formulated in terms of the orientation angles, number of plies, and material properties. The method presented has, in varying degrees, shown that the design of a laminate can be accomplished using strain energy minimization as the primary criteria. The results of various combinations of applied constraints in the optimized design process are presented and discussed

Neither playing the game nor keeping it real: media logics and Big Brother

Sam Pepper, one of the contestants in Big Brother 11, at one point accused fellow housemates Josie and John James of feigning romantic feelings for each other in order to cash in on lucrative deals with celebrity magazines such as OK! and Hello!. The provocation caused much apparent offence, and led to a prolonged and predominantly rancorous debate about authenticity and inauthenticity, soon extending to revelations that other housemates (Rachel, Corinne) aimed to appear in soft pornography titles like Nuts and Zoo, and as such, ‘couldn’t be trusted’. The clear subtext was that any economic motivation was considered a breach of the rules of the Big Brother game – not the explicit parameters of the competition, but the spirit in which it should be played. Being a worthy winner is a matter of who you are rather than what you do, which raises the question of how we came to know Josie and co, as well as how we come to know celebrity selves generally. If BB has taught us anything about the formation of mediated selves, it is that an authentic mediated self cannot exist – and yet authenticity still matters. This piece reflects on this tension and its implications for our increasingly reflexive media culture

Clueless in the city: conceptualizations of the city in German environmentalism

"Um erfolgreich zu sein, brauchen soziale Bewegungen ein Credo, das Eigenschaften, Ursachen und mögliche Lösungen eines sozialen Problems so popularisiert, dass potentielle Anhänger und Unterstützer motiviert sind, sich in vielfältigen Formen zu engagieren. In dem Vortrag werden die Verfasser argumentieren, dass es den deutschen Umweltschutzbewegungen in den verschiedenen Zeitepochen bisher nicht gelungen ist ein anziehendes Gesellschaftsmodell zu entwickeln, in dem die 'Stadt' bzw. urbane Lebensformen einen positiven Beitrag zur Qualität der Umwelt leisten können. Dies ist immer ein Kernmangel der Bewegung gewesen und bleibt es vermutlich auch in Zukunft. Dieses Manko ist tief verwurzelt in der Geschichte der deutschen Umweltbewegungen. Der Vortrag wird Grundzüge dieser spezifischen Vorkriegsgeschichte der Stadtfeindlichkeit darstellen. Desgleichen werden die neue Umweltbewegung der 70er und 80er Jahren analysiert. Erst jetzt wurde hier die Stadt in eine umfassende gegenkulturelle Theorie von Umweltproblemen und -lösungen einbezogen. Die Stadt und ihre Industrien allerdings wurden auch in diesen Konzepten lediglich als Verursacher der Probleme betrachtet. Einige der von der Umweltbewegung geförderten Maßnahmen konnten durchgesetzt werden, aber die Hiobsbotschaften auf das eigene Auto und das eigene Haus im Grünen zu verzichten, wie auf den Konsum, waren nicht umzusetzen. Obwohl die Umweltorganisationen heute auch weiterhin viele Unterstützer haben und sich eines gewissen Wachstums erfreuen können, haben sie ihre Strategien insofern geändert, dass jetzt der Naturschutz in Deutschland und in den Entwicklungsländern in den Vordergrund gestellt wird. Im Kampf gegen den Stadtverkehr und Landschaftszersiedlung werden nur noch Rückzugsgefechte betrieben und eine grundsätzliche Kritik der städtischen Konsumgesellschaft wird nicht mehr propagiert. Gleichwohl könnten diese neuen Konzepte zur nachhaltigen Stadtentwicklung ironischerweise die Eckpfeiler eines positiven Konzepts von Stadt und Umwelt begründen, dies allerdings, angesichts des wirtschaftspolitischen Klimas, mit bisher wenig Resonanz in Politik und in der Bevölkerung." (Autorenreferat

New Protocols and Lower Bound for Quantum Secret Sharing with Graph States

We introduce a new family of quantum secret sharing protocols with limited quantum resources which extends the protocols proposed by Markham and Sanders and by Broadbent, Chouha, and Tapp. Parametrized by a graph G and a subset of its vertices A, the protocol consists in: (i) encoding the quantum secret into the corresponding graph state by acting on the qubits in A; (ii) use a classical encoding to ensure the existence of a threshold. These new protocols realize ((k,n)) quantum secret sharing i.e., any set of at least k players among n can reconstruct the quantum secret, whereas any set of less than k players has no information about the secret. In the particular case where the secret is encoded on all the qubits, we explore the values of k for which there exists a graph such that the corresponding protocol realizes a ((k,n)) secret sharing. We show that for any threshold k> n-n^{0.68} there exists a graph allowing a ((k,n)) protocol. On the other hand, we prove that for any k< 79n/156 there is no graph G allowing a ((k,n)) protocol. As a consequence there exists n_0 such that the protocols introduced by Markham and Sanders admit no threshold k when the secret is encoded on all the qubits and n>n_0

Rainy downdrafts in abyssal atmospheres

Results from Juno's microwave radiometer indicate non-uniform mixing of ammonia vapor in Jupiter's atmosphere down to tens of bars, far beneath the cloud level. Helioseismic observations suggest solar convection may require narrow, concentrated downdrafts called entropy rain to accommodate the Sun's luminosity. Both observations suggest some mechanism of non-local convective transport. We seek to predict the depth that a concentrated density anomaly can reach before efficiently mixing with its environment in bottomless atmospheres. We modify classic self-similar analytical models of entraining thermals to account for the compressibility of an abyssal atmosphere. We compare these models to the output of high resolution three dimensional fluid dynamical simulations to more accurately model the chaotic influence of turbulence. We find that localized density anomalies propagate down to ~3-8 times their initial size without substantially mixing with their environment. Our analytic model accurately predicts the initial flow, but the self-similarity assumption breaks down after the flow becomes unstable at a characteristic penetration depth. In the context of Jupiter, our findings suggest that precipitation concentrated into localized downdrafts of size ~20km can coherently penetrate to on the order of a hundred kilometers (tens of bars) beneath its initial vaporization level without mixing with its environment. This finding is consistent with expected convective storm length-scales, and Juno MWR measurements of ammonia depletion. Compositional gradients of volatiles beneath their cloud levels may be common on stormy giant planets. In the context of the Sun, we find that turbulent downdrafts in abyssal atmospheres cannot maintain their coherence through the Sun's convective layer, a potential challenge for the entropy rain hypothesis.Comment: 20 pages, 16 figures. Accepted by A&

The political phenomenology of war reporting

Drawing on interviews with war correspondents, editors, political and military personnel, this article investigates the political dimension of the structuration and structuring effects of the reporter’s experience of journalism. Self-reflection and judgements about colleagues confirm that there are dominant norms for interpreting and acting in conflict scenarios which, while contingent upon socio-historical context, are interpreted as natural. But the prevalence of such codes masks the systematically misrecognized symbolic systems of mystification and ambivalence – systems which reproduce hierarchies and gatekeeping structures in the field, but which are either experienced as unremarkable, dismissed with irony and cynicism, or not present to the consciousness of the war correspondent. The article builds on recent theories of journalistic disposition, ideology, discourse and professionalism, and describes the political dimension of journalistic practice perceived in the field as apolitical. It addresses the gendering of war correspondence, the rise of the journalist as moral authority, and questions the extent to which respondent reflections can be defensibly analytically determined

The uses and functions of ageing celebrity war reporters

This article starts from the premise that recognition of professional authority and celebrity status depends on the embodiment and performance of field-specific dispositional practices: there’s no such thing as a natural, though we often talk about journalistic instinct as something someone simply has or doesn’t have. Next, we have little control over how we are perceived by peers and publics, and what we think are active positioning or subjectifying practices are in fact, after Bourdieu, revelations of already-determined delegation. The upshot is that two journalists can arrive at diametrically opposed judgements on the basis of observation of the same actions of a colleague, and as individuals we are blithely hypocritical in forming (or reciting) evaluations of the professional identity of celebrities. Nowhere is this starker than in the discourse of age-appropriate behaviour, which this paper addresses using the examples of ‘star’ war reporters John Simpson, Kate Adie and Martin Bell. A certain rough-around-the-edges irreverence is central to dispositional authenticity amongst war correspondents, and for ageing hacks this incorporates gendered attitudes to sex and alcohol as well as indifference to protocol. And yet perceived age-inappropriate sexual behaviour is also used to undermine professional integrity, and the paper ends by outlining the phenomenological context that makes possible this effortless switching between amoral and moralising recognition by peers and audiences alike