901,345 research outputs found

    Verifying security protocols by knowledge analysis

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    This paper describes a new interactive method to analyse knowledge of participants involved in security protocols and further to verify the correctness of the protocols. The method can detect attacks and flaws involving interleaving sessions besides normal attacks. The implementation of the method in a generic theorem proving environment, namely Isabelle, makes the verification of protocols mechanical and efficient; it can verify a medium-sized security protocol in less than ten seconds. As an example, the paper finds the flaw in the Needham-Schroeder public key authentication protocol and proves the secure properties and guarantees of the protocol with Lowe's fix to show the effectiveness of this method

    Soft Power to Whom? A Critical Analysis of the Publicity Film “CPC (Communist Party of China) is With You Along the Way” in Relation to China’s Soft Power Project

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    The existing literature on China’s soft power is mainly concerned with its success or failure, ignoring the ideological tensions between the Chinese state's international pursuit of soft power and its efforts at reviving the popularity of socialist ideology at home in a country profoundly transformed by modernisation and globalisation processes. This article argues that such ideological tensions should be contextualised and critically analysed by employing an approach informed by critical globalisation studies, particularly by the power-to-whom critique. It offers a critical analysis of the CPC is With You Along the Way film, a notable recent example of the CPC’s publicity videos in the context of its pursuit of soft power. Borrowing Reisigl and Wodak’s discourse-historical approach (DHA) in addition to the analytical devices for the study of ideology from Eagleton and van Dijk, the article argues that CPC is With You Along the Way illustrates a shift in the party’s ideological approach to the question ‘(soft) power to whom?’

    Thermal fluctuations and anomalous elasticity of homogeneous nematic elastomers

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    We present a unified formulation of a rotationally invariant nonlinear elasticity for a variety of spontaneously anisotropic phases, and use it to study thermal fluctuations in nematic elastomers and spontaneously anisotropic gels. We find that in a thermodynamic limit homogeneous nematic elastomers are universally incompressible, are characterized by a universal ratio of shear moduli, and exhibit an anomalous elasticity controlled by a nontrivial low temperature fixed point perturbative in D=3-epsilon dimensions. In three dimensions, we make predictions that are asymptotically exact.Comment: 4 RevTeX pgs,,submitted to Europhysics Letter

    Inner product computation for sparse iterative solvers on\ud distributed supercomputer

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    Recent years have witnessed that iterative Krylov methods without re-designing are not suitable for distribute supercomputers because of intensive global communications. It is well accepted that re-engineering Krylov methods for prescribed computer architecture is necessary and important to achieve higher performance and scalability. The paper focuses on simple and practical ways to re-organize Krylov methods and improve their performance for current heterogeneous distributed supercomputers. In construct with most of current software development of Krylov methods which usually focuses on efficient matrix vector multiplications, the paper focuses on the way to compute inner products on supercomputers and explains why inner product computation on current heterogeneous distributed supercomputers is crucial for scalable Krylov methods. Communication complexity analysis shows that how the inner product computation can be the bottleneck of performance of (inner) product-type iterative solvers on distributed supercomputers due to global communications. Principles of reducing such global communications are discussed. The importance of minimizing communications is demonstrated by experiments using up to 900 processors. The experiments were carried on a Dawning 5000A, one of the fastest and earliest heterogeneous supercomputers in the world. Both the analysis and experiments indicates that inner product computation is very likely to be the most challenging kernel for inner product-based iterative solvers to achieve exascale
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