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Application of thermoelectric aging models to polymeric insulation in cable geometry
The life expressions of models of insulation ageing are functions of temperature and field as well as material parameters. A methodology is presented that allows these models to be applied to a cable geometry in which there is a radial variation of both field and temperature. In this way material parameters can be extracted from cable data. The methodology is illustrated using one such model and the parameters deduced from cable failure distributions are compared with those obtained for thin films. This comparison allows conclusions to be drawn about how the ageing process affects specimens of the same material with different volumes
Copyright Contracts and Earnings of Visual Creators: A Survey of 5,800 British Designers, Fine Artists, Illustrators and Photographers
There is a common perception that digitisation has prompted changes in creative labour markets. In particular, it is widely assumed that exploiters insist on "grabbing rights" (i.e. broadly conceived assignments of rights), that visual artists are not able to negotiate, that they are paid less and less, and that they are compelled to waive their moral rights.
This study suggests a much more equivocal picture. In place of a straightforward narrative of decline, the results of the survey suggest that in most fields there has been less change over the last decade than one might have expected: that, terms of exploitation are most often about the same. That is not to say that there are no discernible changes in particular occupations and media. Respondents and interviewees identify some important shifts. Perhaps surprisingly, it seems there are changes in practice that are, from the creator's perspective, both positive and negative. The most positive change is identified amongst the fine artists where half (50%) see their personal bargaining position as having improved, with only 6% perceiving a weakening. The most disturbing changes are in relation to photographers. About half of all photographers (49%) say their bargaining position has worsened, with only 22% reporting improvements. A significant percentage of photographers (40%) report an increase in assignments (compared with 6% who think they have decreased). Moreover, 24% report an increase in moral rights waivers (compared to 3% who identify a decrease), and a decline in the practice of attribution. 31% of photographers see attribution as decreasing over the last decade, and only 8% increasing. 28% say income from secondary use has decreased, while only 16% say it has decreased
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Application of polymer ageing models to power cables
Ageing models have been developed to predict the lifetime of polymeric insulation subject to electro-thermal stresses. We present here a method for applying the models to situations in which the field is not constant over the whole specimen, as for cable geometry. The method has been applied to characteristic lifetime data from AC ageing experiments on cables. The results are presented, and the effect of insulation volume upon the model parameters is discussed
Measuring the Superfluid Fraction of an Ultracold Atomic Gas
We propose a method to measure the superfluid fraction of an atomic gas. The
method involves the use of a vector potential generated by optical beams with
non-zero angular momentum to simulate uniform rotation. The induced change in
angular momentum of the atomic gas can be measured spectroscopically. This
allows a direct determination of the superfluid fraction.Comment: 4 pages, 2 figure
Charge-ice dynamics in the negative thermal expansion material Cd(CN)
We use variable-temperature (150--300\,K) single-crystal X-ray diffraction to
re-examine the interplay between structure and dynamics in the ambient phase of
the isotropic negative thermal expansion (NTE) material Cd(CN). We find
strong experimental evidence for the existence of low-energy vibrational modes
that involve off-centering of Cd ions. These modes have the effect of
increasing network packing density---suggesting a mechanism for NTE that is
different to the generally-accepted picture of correlated Cd(C/N) rotation
modes. Strong local correlations in the displacement directions of neighbouring
cadmium centres are evident in the existence of highly-structured diffuse
scattering in the experimental X-ray diffraction patterns. Monte Carlo
simulations suggest these patterns might be interpreted in terms of a basic set
of `ice-rules' that establish a mapping between the dynamics of Cd(CN) and
proton ordering in cubic ice VII.Comment: 5 pages, 5 figures, submitted to PR
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