18,326 research outputs found

    Elastic-plastic analysis of functionally graded bars under torsional loading

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    In this paper a new integral equation solution to the elastic-plastic problem of functionally graded bars under torsional loading is presented. The formulation is general in the sense that it can be applied to an arbitrary cross-section made of any type of elastoplastic material. In material science the Functionally Graded Material (FGM) is a non-homogeneous composite which performs as a single-phase material, by unifying the best properties of its constituent phase material. The nonlinear elastic-plastic behavior is treated by employing the deformation theory of plasticity. According to this theory, the material constants are assumed variable within the cross section, and are updated through an iterative process so as the equivalent stress and strain at each point coincide with the uniaxial material curve. In this investigation a new straightforward nonlinear procedure is introduced in the deformation theory of plasticity which simplifies the solution method. At each iteration step, the warping function is obtained by solving the torsion problem of a non-homogeneous isotropic bar using the Boundary Element Method (BEM) in conjunction with the Analog Equation Method (AEM). Without restricting the generality, the FGM material is comprised of a ceramic phase and a metal phase. The ceramic is assumed to behave linearly elastic, whereas the metal is modeled as an elastic-linear hardening material. Furthermore, the TTO homogenization scheme for estimating the effective properties of the two-phase FGM was adopted. Several bars with various cross-sections and material types are analyzed, in order to validate the proposed model and exemplify its salient features. Moreover, useful conclusion are drawn from the elastic-plastic behavior of functionally graded bars under torsional loading

    What is really in the economic partnership agreements for the Southern African region? A perspective from Botswana’s beef export markets

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    The signing of the Economic Partnership Agreements (EPAs) between the European Union (EU) and the African Caribbean Pacific (ACP) nations dominated the multilateral trade agenda in late 2007 and early 2008. While the Caribbean nations signed the full EPAs, some of the African countries only singed interim agreements with the EU and a number of West African countries chose not to sign any EPA. Using the case of Botswana’s export markets, especially in agriculture, it is argued that the interim Southern African Development Community (SADC) EPA, which was signed by Botswana and her neighbours, with the exception of South Africa, may have been economically sensible in protecting Botswana’s rural poor, at least in the short run. By tracing trade flows from the border to specifically poor sectors of the country, the importance of the beef exports sector to the poor and rural communities was found. The potential effects on the most significant exports of tariff bands associated with preferential agreements with the EU were found to be most beneficial in comparison to the Most Favoured Nation (MFN) and the South Africa-EU Trade Development and Cooperation Agreement (TDCA) tariff bands. But it is also argued that the EPA will most likely have far reaching long run costs on regional economic development and institutional integration, within the SADC and Southern African Customs Union (SACU).Botswana, economic partnership agreements, European Union, exports, beef,

    Augmented Sustainability Measures for Scotland

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    We estimate and compare two empirical measures of the weak sustainability of an economy for the first time: the change in augmented green net national product (GNNP), and the interest on augmented genuine savings (GS). Yearly calculations are given for each measure for Scotland during 1992-99. Augmentation means including, using projections to 2020, production possibilities enabled by exogenous technical progress or changing terms of trade. In passing, we clarify the treatment of environmental expenditures in green accounting. The change in augmented GNNP and interest on augmented GS are both always positive, showing no sustainability problem for Scotland; but the former greatly exceeds the latter, showing an unresolved problem with the theorysustainability, Scotland, genuine savings, green NNP, augmentation

    Cheese Makers are Always Women: Gendered Representations of Farm Life in the Agricultural Press

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    Drawing upon the 'Farmlife' pages of Farmer's Weekly, the most significant farming publication in the UK, this paper assesses the ways in which gender identities in farming are represented by its text and images. Lead articles from 1976 and 1996 issues of Farmlife are taken as the research focus to determine how representations have altered in line with restructuring of the agricultural industry. Reference is made to Connell's (1987) notions of hegemonic masculinity and emphasised femininity to inform the analysis about the ways in which these gender identities are (re)produced through the British farming media. A simple typology is derived from the articles which assists in revealing a remarkable degree of consistency in the portrayal of gender identities over time. The findings augment evidence from international research suggesting that dominant gender identities within agriculture are being perpetuated through the farming media. The implications of this are highlighted and suggestions made for research with the consumers of these media products

    X-Ray Wakes in Abell 160

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    `Wakes' of X-ray emission have now been detected trailing behind a few (at least seven) elliptical galaxies in clusters. To quantify how widespread this phenomenon is, and what its nature might be, we have obtained a deep (70 ksec) X-ray image of the poor cluster Abell 160 using the ROSAT HRI. Combining the X-ray data with optical positions of confirmed cluster members, and applying a statistic designed to search for wake-like excesses, we confirm that this phenomenon is observed in galaxies in this cluster. The probability that the detections arise from chance is less than 0.0038. Further, the wakes are not randomly distributed in direction, but are preferentially oriented pointing away from the cluster centre. This arrangement can be explained by a simple model in which wakes arise from the stripping of their host galaxies' interstellar media due to ram pressure against the intracluster medium through which they travel.Comment: 7 pages, 7 figures, accepted for publication in MNRA

    Developing the repository manager community

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    This paper describes activities which have taken place within the UK institutional repository (IR) sector focusing on developing a community of practice through the sharing of experiences and best practice. This includes work done by the UK Council of Research Repositories (UKCoRR) and other bodies, together with informal activities, such as sharing the experience of organising Open Access Week events. The paper also considers future work to be undertaken by UKCoRR to continue developing the community

    Signatures of exosolar planets in dust debris disks

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    We apply our recently elaborated, powerful numerical approach to the high-resolution modeling of the structure and emission of circumstellar dust disks, incorporating all relevant physical processes. Specifically, we examine the resonant structure of a dusty disk induced by the presence of one planet. It is shown that the planet, via resonances and gravitational scattering, produces (1) an asymmetric resonant dust belt with one or more clumps intermittent with one or a few off-center cavities; and (2) a central cavity void of dust. These features can serve as indicators of a planet embedded in the circumstellar dust disk and, moreover, can be used to determine its major orbital parameters and even the mass of the planet. The results of our study reveal a remarkable similarity with various types of highly asymmetric circumstellar disks observed with the James Clerk Maxwell Telescope around Epsilon Eridani and Vega. The proposed interpretation of the clumps in those disks as being resonant patterns is testable -- it predicts the asymmetric design around the star to revolve, viz., by 1.2--1.6 deg/yr about Vega and 0.6--0.8 deg/yr about Epsilon Eri.Comment: to be published in ApJ Letters (v. 537, July 10, 2000), 5 pages, incl. 2 figures. Position of (color) Fig. 2 corrected to make the Figure caption fully readabl

    Alternative Archaeological Representations within Virtual Worlds

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    Traditional VR methods allow the user to tour and view the virtual world from different perspectives. Increasingly, more interactive and adaptive worlds are being generated, potentially allowing the user to interact with and affect objects in the virtual world. We describe and compare four models of operation that allow the publisher to generate views, with the client manipulating and affecting specific objects in the world. We demonstrate these approaches through a problem in archaeological visualization
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