2. |
- Brady, Alan C, et al.
(author)
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Discrimination of tactile rendering on virtual surfaces
- 2006
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In: ; , s. 107-108
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Conference paper (peer-reviewed)abstract
- An array of vibrating contactors on the fingertip can provide information about virtual objects during active exploration of a virtual environment – for example, information about contact area, edges, corners and surface texture. For the operation of such a device, it is necessary to generate in real time an individually specified drive waveform for each contactor of the stimulator array. To reduce the complexity of the problem, a system has been developed at Exeter in which each drive signal is specified as a mixture of a small number of sinewaves. The aim of this study is to investigate the discrimination of the virtual textures which can be produced in this way, with the aim of developing a library of textures for use in virtual reality applications. Textures produced by mixtures of sinewaves are differentiated in terms of the mean amplitude and the spatial distribution at each sinewave frequency. Experimental questions include the number of categories (i.e., requency/amplitude/spatial combinations) that can be distinguished and the possible correspondence between virtual and real textures.
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3. |
- von Hellermann, M G, et al.
(author)
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Complex spectra in fusion plasmas
- 2005
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In: Physica Scripta. - 0031-8949. ; T120, s. 19-29
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Journal article (peer-reviewed)abstract
- The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development of sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment of the plasma environment. The successful merging of the two worlds has led to routine diagnostic procedures which have contributed enormously to the understanding of underlying plasma processes and also to a wide acceptance of spectroscopy as a reliable diagnostic method. In this paper three characteristic types of spectra of current and continuing interest are presented. The first is that of medium/ heavy species with many ionisation stages revealed in survey VUV and XUV spectra. Such species occur as control gases, as wall materials, as ablated heavy species and possible as layered wall dopants for monitoring erosion. The spectra are complex with line- like and quasi-continuum regions and are amenable to advanced 'pattern recognition' methods. The second type is of few electron, highly ionised systems observed as line-of-sight integrated passive emission spectra in the soft X-ray region. They are analysed successfully in terms of plasma parameters through matching of observation with predicted synthetic spectra. Examples used here include highly resolved helium-like emission spectra of argon, iron and titanium observed on the tokamaks TEXTOR and Tore Supra. The third type, and the emphasis of this work, comprises spectra linked to active beam spectroscopy, that is, charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy ( BES). In this case, a complex spectrum is again composed of a ( usually) dominating active spectrum and an underlying passive emission spectrum. Its analysis requires modelling of both active and passive features. Examples used here are from the CXRS diagnostic at JET and TEXTOR. They display characteristic features of the main light impurity ions (C+6, He+2, N+7, Ne+10 and Ar+18), as well as that of the bulk plasma ions, H+, D+ and T+. A main conclusion is that spectral complexity is not necessarily negative, but that 'complex structures' can provide a rich source of information on the plasma and its parameters - provided it is matched with integrated analysis - and that the methods can have universal applicability. In the present preparatory phase of the next generation fusion experiment ITER ( International Thermonuclear Experimental Reactor) the concepts and expectations of complex spectra and integrated data analysis play an important role in the design and optimisation procedure of the ITER diagnostic assembly.
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