983 resultados para modern techniques


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This study is a pragmatic description of the evolution of the genre of English witchcraft pamphlets from the mid-sixteenth century to the end of the seventeenth century. Witchcraft pamphlets were produced for a new kind of readership semi-literate, uneducated masses and the central hypothesis of this study is that publishing for the masses entailed rethinking the ways of writing and printing texts. Analysis of the use of typographical variation and illustrations indicates how printers and publishers catered to the tastes and expectations of this new audience. Analysis of the language of witchcraft pamphlets shows how pamphlet writers took into account the new readership by transforming formal written source materials trial proceedings into more immediate ways of writing. The material for this study comes from the Corpus of Early Modern English Witchcraft Pamphlets, which has been compiled by the author. The multidisciplinary analysis incorporates both visual and linguistic aspects of the texts, with methodologies and theoretical insights adopted eclectically from historical pragmatics, genre studies, book history, corpus linguistics, systemic functional linguistics and cognitive psychology. The findings are anchored in the socio-historical context of early modern publishing, reading, literacy and witchcraft beliefs. The study shows not only how consideration of a new audience by both authors and printers influenced the development of a genre, but also the value of combining visual and linguistic features in pragmatic analyses of texts.

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Various Tb theorems play a key role in the modern harmonic analysis. They provide characterizations for the boundedness of Calderón-Zygmund type singular integral operators. The general philosophy is that to conclude the boundedness of an operator T on some function space, one needs only to test it on some suitable function b. The main object of this dissertation is to prove very general Tb theorems. The dissertation consists of four research articles and an introductory part. The framework is general with respect to the domain (a metric space), the measure (an upper doubling measure) and the range (a UMD Banach space). Moreover, the used testing conditions are weak. In the first article a (global) Tb theorem on non-homogeneous metric spaces is proved. One of the main technical components is the construction of a randomization procedure for the metric dyadic cubes. The difficulty lies in the fact that metric spaces do not, in general, have a translation group. Also, the measures considered are more general than in the existing literature. This generality is genuinely important for some applications, including the result of Volberg and Wick concerning the characterization of measures for which the analytic Besov-Sobolev space embeds continuously into the space of square integrable functions. In the second article a vector-valued extension of the main result of the first article is considered. This theorem is a new contribution to the vector-valued literature, since previously such general domains and measures were not allowed. The third article deals with local Tb theorems both in the homogeneous and non-homogeneous situations. A modified version of the general non-homogeneous proof technique of Nazarov, Treil and Volberg is extended to cover the case of upper doubling measures. This technique is also used in the homogeneous setting to prove local Tb theorems with weak testing conditions introduced by Auscher, Hofmann, Muscalu, Tao and Thiele. This gives a completely new and direct proof of such results utilizing the full force of non-homogeneous analysis. The final article has to do with sharp weighted theory for maximal truncations of Calderón-Zygmund operators. This includes a reduction to certain Sawyer-type testing conditions, which are in the spirit of Tb theorems and thus of the dissertation. The article extends the sharp bounds previously known only for untruncated operators, and also proves sharp weak type results, which are new even for untruncated operators. New techniques are introduced to overcome the difficulties introduced by the non-linearity of maximal truncations.

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After microscopic characterization of the size distributions of gold clusters, deposited on carbon substrates by vacuum evaporation or by soft landing, Au(4f') binding energy of the clusters has been measured as a function of the mean cluster size. Similar measurements have been carried out on Au clusters prepared from sols by chemical means and high-nuclearity cluster compounds. In general, small clusters with a mean diameter of $2 nm show significantly larger binding energies than the bulk metal value, due to the onset of nonmetallicity. Nonmetallicity manifests itself in terms of a tunneling conductance gap only in clusters of diameter ;5 1 nm containing 40 atoms or fewer.

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Electrolytes based on polyethylene glycol (PEG, mol.wt.8000) and LiCl of compositions, (PEG)(x)LiCl, x=4, 6, 8, 10, 12, 40, 60, where x is the O/Li ratio, were prepared by solution casting from methanol solutions. FTIR studies indicate that the ether oxygens of the polymer chain participate in Li+ ion conduction. The presence of a salt-polymer complex that melts around 190 degrees C was evidenced by DSC measurements for the electrolytes with compositions x<12. The highest conductivity was obtained at the composition x=10 which was attributed to the presence of a mostly amorphous compound. NMR measurements indicated two regions of motional narrowing, one attributable to the glass transition and another to translational diffusion.

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In the Himalayas, a large area is covered by glaciers and seasonal snow and changes in its extent can influence availability of water in the Himalayan Rivers. In this paper, changes in glacial extent, glacial mass balance and seasonal snow cover are discussed. Glacial retreat was estimated for 1868 glaciers in 11 basins distributed in the Indian Himalaya since 1962. The investigation has shown an overall reduction in glacier area from 6332 to 5329km2 from 1962 to 2001/2 - an overall deglaciation of 16%. Snow line at the end of ablation season on the Chhota Shigri glacier observed using field and satellite methods suggests a change in altitude from 4900 to 5200m from the late 1970s to present. Seasonal snow cover was monitored in the 28 river sub-basins using normalized difference snow index (NDSI) technique in Central and Western Himalaya. The investigation has shown that in the early part of winter, i.e. from October to December, a large amount of snow retreat was observed. For many basins located in lower altitude and in the south of the Pir Panjal range, snow ablation was observed throughout the winter season. In addition, average stream runoff of the Baspa basin for the month of December increased by 75%. This combination of glacial retreat, negative mass balance, early melting of seasonal snow cover and winter-time increase in stream runoff might suggest an influence of global warming on the Himalayan cryosphere.

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A new computational tool is presented in this paper for suboptimal control design of a class of nonlinear distributed parameter systems. First proper orthogonal decomposition based problem-oriented basis functions are designed, which are then used in a Galerkin projection to come up with a low-order lumped parameter approximation. Next, a suboptimal controller is designed using the emerging /spl thetas/-D technique for lumped parameter systems. This time domain sub-optimal control solution is then mapped back to the distributed domain using the same basis functions, which essentially leads to a closed form solution for the controller in a state feedback form. Numerical results for a real-life nonlinear temperature control problem indicate that the proposed method holds promise as a good suboptimal control design technique for distributed parameter systems.

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Joining of dissimilar metals involves a number of scientific issues, the modelling of which offers unique challenges. This review discusses the complexities in different joining processes and dissimilar combinations, and the corresponding computational techniques that have the potential to address the same. Future directions in modelling at both macroscopic and microscopic scales are also suggested.

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A scanning tunneling microscopy study of carbon nanocapsules (onions) is reported for the first time. Spherulitic graphite is shown to be purely crystalline graphite based on X-ray diffraction and electron microscopy studies.