3 resultados para Uniform step method

em Nottingham eTheses


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In the area of linguistics and language teaching, science fiction is useful in very many ways. An obvious way is that it sets up many complex and rich worlds and outlines the sorts of adjustments that language must make in those contexts. It thus draws a strong link between language and context; it shows how the construction of reality is largely a matter of language; and it speculates on where we are linguistically heading. It is a useful mirror on language development. Extrapolating the dialects of the future has been the province of science fiction in the last century. Though few SF writers are professional linguists, their method in general tends to take a holistic view of form, meaning and social context. Characters in science fiction are not individuals but are 'everyman' tokens, and the language they use symbolises the culture they inhabit. Linguistic extrapolation in science fiction thus treats language both as the technology of communication and as an index of social change. In this paper, I argue that predicting the language of the future, though extremely difficult, is possible. I call this new discipline chronolinguistics, and I set out the draft principles and parameters of a chronolinguistics, based on the future languages speculated by John Brunner, Russell Hoban, William Gibson, Greg Bear, Neal Stephenson and Iain M.Banks.

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A two stage approach to performing ab initio calculations on medium and large sized molecules is described. The first step is to perform SCF calculations on small molecules or molecular fragments using the OPIT Program. This employs a small basis set of spherical and p-type Gaussian functions. The Gaussian functions can be identified very closely with atomic cores, bond pairs, lone pairs, etc. The position and exponent of any of the Gaussian functions can be varied by OPIT to produce a small but fully optimised basis set. The second stage is the molecular fragments method. As an example of this, Gaussian exponents and distances are taken from an OPIT calculation on ethylene and used unchanged in a single SCF calculation on benzene. Approximate ab initio calculations of this type give much useful information and are often preferable to semi-empirical approaches, since the nature of the approximations involved is much better defined.

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We propose a pre-processing mesh re-distribution algorithm based upon harmonic maps employed in conjunction with discontinuous Galerkin approximations of advection-diffusion-reaction problems. Extensive two-dimensional numerical experiments with different choices of monitor functions, including monitor functions derived from goal-oriented a posteriori error indicators are presented. The examples presented clearly demonstrate the capabilities and the benefits of combining our pre-processing mesh movement algorithm with both uniform, as well as, adaptive isotropic and anisotropic mesh refinement.