491 research outputs found
Effects of fiber, matrix, and interphase on carbon fiber composite compression strength
The major goal of this project was to obtain basic information on compression failure properties of carbon fiber composites. To do this, we investigated fiber effects, matrix effects, and fiber/matrix interface effects. Using each of nine fiber types, we prepared embedded single-fiber specimens, single-ply specimens, and full laminates. From the single-fiber specimens, in addition to the standard fragmentation test analysis, we were able to use the low crack density data to provide information about the distribution of fiber flaws. The single-ply specimens provided evidence of a correlation between the size of kink band zones and the quality of the interface. Results of the laminate compression experiments mostly agreed with the results from single-ply experiments, although the ultimate compression strengths of laminates were higher. Generally, these experiments showed a strong effect of interfacial properties. Matrix effects were examined using laminates subjected to precracking under mixed-mode loading conditions. A large effect of precracking conditions on the mode 1 toughness of the laminates was found. In order to control the properties of the fiber/matrix interface, we prepared composites of carbon fiber and polycarbonate and subjected these to annealing. The changes in interfacial properties directly correlated with changes in compression strength
Re-identification of c. 15 700 cal yr BP tephra bed at Kaipo Bog, eastern North Island: implications for dispersal of Rotorua and Puketarata tephra beds.
A 10 mm thick, c. 15 700 calendar yr BP (c. 13 100 14C yr BP) rhyolitic tephra bed in the well-studied montane Kaipo Bog sequence of eastern North Island was previously correlated with Maroa-derived Puketarata Tephra. We revise this correlation to Okataina-derived Rotorua Tephra based on new compositional data from biotite phenocrysts and glass. The new correlation limits the known dispersal of Puketarata Tephra (sensu stricto, c. 16 800 cal yr BP) and eliminates requirements to either reassess its age or to invoke dual Puketarata eruptive events. Our data show that Rotorua Tephra comprises two glass-shard types: an early-erupted low-K2O type that was dispersed mostly to the northwest, and a high-K2O type dispersed mostly to the south and southeast, contemporary with late-stage lava extrusion. Late-stage Rotorua eruptives contain biotite that is enriched in FeO compared with biotite from Puketarata pyroclastics. The occurrence of Rotorua Tephra in Kaipo Bog (100 km from the source) substantially extends its known distribution to the southeast. Our analyses demonstrate that unrecognised syn-eruption compositional and dispersal changes can cause errors in fingerprinting tephra deposits. However, the compositional complexity, once recognised, provides additional fingerprinting criteria, and also documents magmatic and dispersal processes
Benthic phosphorus cycling within the Eurasian marginal sea ice zone
The Arctic Ocean region is currently undergoing dramatic changes, which will likely alter the nutrient cycles that underpin Arctic marine ecosystems. Phosphate is a key limiting nutrient for marine life but gaps in our understanding of the Arctic phosphorus (P) cycle persist. In this study, we investigate the benthic burial and recycling of phosphorus using sediments and pore waters from the Eurasian Arctic margin, including the Barents Sea slope and the Yermak Plateau. Our results highlight that P is generally lost from sediments with depth during organic matter respiration. On the Yermak Plateau, remobilization of P results in a diffusive flux of P to the seafloor of between 96 and 261â”molâmâ2âyrâ1. On the Barents Sea slope, diffusive fluxes of P are much larger (1736â2449â”molâmâ2âyrâ1), but these fluxes are into near-surface sediments rather than to the bottom waters. The difference in cycling on the Barents Sea slope is controlled by higher fluxes of fresh organic matter and active iron cycling. As changes in primary productivity, ocean circulation and glacial melt continue, benthic P cycling is likely to be altered with implications for P imported into the Arctic Ocean Basin
'Mindless markers of the nation': The routine flagging of nationhood across the visual environment
The visual environment has increasingly been used as a lens with which to understand wider processes of social and economic change with studies employing in-depth qualitative approaches to focus on, for example, gentrification or trans-national networks. This exploratory paper offers an alternative perspective by using a novel method, quantitative photo mapping, to examine the extent to which a particular socio-cultural marker, the nation, is âflaggedâ across three contrasting sites in Britain. As a multi-national state with an increasingly diverse population, Britain offers a particularly fruitful case study, drawing in debates around devolution, European integration and Commonwealth migration. In contributing to wider debates around banal nationalism, the paper notes the extent to which nations are increasingly articulated through commerce, consumption and market exchange and the overall significance of everyday markers (signs, objects, infrastructure) in naturalising a national view of the world
Late Holocene palynology and palaeovegetation of tephra-bearing mires at Papamoa and Waihi Beach, western Bay of Plenty, North Island, New Zealand.
The vegetation history of two mires associated with Holocene dunes near the western Bay of Plenty coast, North Island, New Zealand, is deduced from pollen analysis of two cores. Correlation of airfall tephra layers in the peats, and radiocarbon dates, indicate that the mires at Papamoa and Waihi Beach are c. 4600 and c. 2900 conventional radiocarbon years old, respectively. Tephras used to constrain the chronology of the pollen record include Rotomahana (1886 AD), Kaharoa (700 yr B.P.), Taupo (Unit Y; 1850 yr B.P.), Whakaipo (Unit V; 2700 yr B.P.), Stent (Unit Q; 4000 yr B.P.), Hinemaiaia (Unit K; 4600 yr B.P.), and reworked Whakatane (c. 4800 yr B.P.) at Papamoa, and Kaharoa and Taupo at Waihi Beach. Peat accumulation rates at Papamoa from 4600 - 1850 yr B.P. range from 0.94 to 2.64 mm/yr (mean 1.37 mm/yr). At Waihi Beach, from 2900 yr B.P. - present day, they range from 0.11 to 0.21 mm/yr (mean 0.20 mm/yr). Peat accumulation at both sites was slowest from 1850 to 700 yr B.P., suggesting a drier overall climate during this interval. At both sites, the earliest organic sediments, which are underlain by marine or estuarine sands, yield pollen spectra indicating salt marsh or estuarine environments. Coastal vegetation communities declined at both sites, as sea level gradually fell or the coast prograded, and were eventually superseded by a low moor bog at Papamoa, and a mesotrophic swamp forest at Waihi Beach. These differences, and the marked variation in peat accumulation rates, probably reflect local hydrology and are unlikely to have been climatically controlled. The main regional vegetation during this period was mixed northern conifer-angiosperm forest. Kauri (Agathis australis) formed a minor component of these forests, but populations of this tree have apparently not expanded during the late Holocene at these sites, which are near its present southern limit. Occasional shortlived forest disturbances are detectable in these records, in particular immediately following the deposition of Taupo Tephra. However, evidence for forest clearance during the human era is blurred by the downward dislocation of modern adventi ve pollen at these sites, preventing the clear differentiation of the Polynesian and European eras
Exact Solution of Two-Species Ballistic Annihilation with General Pair-Reaction Probability
The reaction process is modelled for ballistic reactants on an
infinite line with particle velocities and and initially
segregated conditions, i.e. all A particles to the left and all B particles to
the right of the origin. Previous, models of ballistic annihilation have
particles that always react on contact, i.e. pair-reaction probability .
The evolution of such systems are wholly determined by the initial distribution
of particles and therefore do not have a stochastic dynamics. However, in this
paper the generalisation is made to , allowing particles to pass through
each other without necessarily reacting. In this way, the A and B particle
domains overlap to form a fluctuating, finite-sized reaction zone where the
product C is created. Fluctuations are also included in the currents of A and B
particles entering the overlap region, thereby inducing a stochastic motion of
the reaction zone as a whole. These two types of fluctuations, in the reactions
and particle currents, are characterised by the `intrinsic reaction rate', seen
in a single system, and the `extrinsic reaction rate', seen in an average over
many systems. The intrinsic and extrinsic behaviours are examined and compared
to the case of isotropically diffusing reactants.Comment: 22 pages, 2 figures, typos correcte
A very conscientious brand: A case study of the BBC's current affairs series Panorama
The reputation of British current affairs and documentary series such as the BBC's Panorama, Channel 4âs Dispatches or the now defunct Granada series World
in Action have rested on an image of conscientious âpublic serviceâ. These popular, long running series have, at various points in their history, acted as the âconscience
of the nationâ, seeking to expose social injustice, investigate misdemeanours by the powerful and take on venal or corrupt vested interest. The BBCâs flagship current
affairs series Panorama is Britainâs longest running television programme and, according to the Panorama website, âthe worldâs longest running investigative TV showâ. It has provided a template for other current affairs series both in Britain, Europe and around the world while undergoing several transformations in form and style since its launch in 1953, the latest and arguably most dramatic being in 2007. This article will chart the development of Panorama as a distinctive, âflagship' current affairs series over six decades. It will attempt to answer why the Panorama brand has survived so long, while so many other notable current affairs series have not. Using research and material from Bournemouth Universityâs Panorama Archive, the Video Active website, the BFI and other European archives this article explores the development of an iconic current affairs series that has, at different stages in its history, proved a template for other news and current affairs programmes. Various breaks and continuities are highlighted in Panoramaâs history and identity, and an attempt will be made to characterise and specify the Panorama âbrandâ and pinpoint the seriesâ successes and failures in reinventing itself in a rapidly changing media context
Capturing Desire: Rhetorical Strategies and the Affectivity of Discourse
In this article I argue that psychoanalytical theory can help us understand the emotional force of political rhetoric. I undertake a theoretical enquiry into the method of interpreting political speeches as strategies of affective persuasion. Both rhetorical and psychoanalytical studies converge in their concern with the production of âplausible storiesâ that aim to fold psychic investments into political judgements. To capture desire, I claim, political rhetoric must articulate âsymptomatic beliefsâ in relation to wider situational exigencies. I sketch three distinct psychoanalytical approaches, each of which emphasises a different scenario of unconscious organisation where rhetorical strategies are pertinent: namely Freudian, Kleinian, and Lacanian approaches. These are then applied to the example of a controversial rhetorical intervention â Enoch Powellâs infamous Birmingham speech of 1968 â to demonstrate the various potential focii when undertaking analysis
Sport for Yes? The role of sporting issues in pro-independence political discourse during the Scottish independence referendum campaign
This article critically considers the extent to which sporting issues were harnessed by pro-independence political campaigners during the Scottish independence referendum campaign. Developments such as the inclusion of sport within the Scottish Governmentâs White Paper on Scottish independence, the establishment of the âWorking Group on Scottish Sportâ and the establishment of the âSport for Yesâ campaign group demonstrate the harnessing of sporting issues as an additional, if somewhat peripheral, debate point in the referendum campaigns (Lafferty 2014, Scottish Government 2013, Working Group on Scottish Sport and Scottish Government 2013, 2014). The latter of these developments, the establishment of the âSport for Yesâ campaign group, is of particular interest, offering evidence of the explicit political mobilisation of past and present athletes in support of the âYes Scotlandâ pro-independence campaign. The use of sport within pro-independence political discourse is therefore scrutinised, drawing upon the principles of critical discourse analysis to explore the ideological assumptions underpinning the discursive representation of sport in relation to Scottish independence
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