1,114,100 research outputs found
Design and use of a hackable digital instrument
This paper introduces the D-Box, a new digital musical instrument specifically designed to elicit unexpected creative uses and to support modification by the performer. Rather than taking a modular approach, the D-Box is a hackable instrument which allows for the discovery of novel working configurations through circuit bending techniques. Starting from the concept of appropriation, this paper describes the design, development and evaluation process lasting more than one year and made in collaboration with musicians and hackers.This work was funded by the UK Engineering and Physical Sciences Research Council under grant EP/K032046/1 (2013-14)
Optimizing infrared to near infrared upconversion quantum yield of β-NaYF<sub>4</sub>:Er<sup>3+</sup> in fluoropolymer matrix for photovoltaic devices
The present study reports for the first time the optimization of the infrared (1523 nm) to near-infrared (980 nm) upconversion quantum yield (UC-QY) of hexagonal trivalent erbium doped sodium yttrium fluoride (β-NaYF4:Er3+) in a perfluorocyclobutane (PFCB) host matrix under monochromatic excitation. Maximum internal and external UC-QYs of 8.4% ± 0.8% and 6.5% ± 0.7%, respectively, have been achieved for 1523 nm excitation of 970 ± 43 Wm−2 for an optimum Er3+ concentration of 25 mol% and a phosphor concentration of 84.9 w/w% in the matrix. These results correspond to normalized internal and external efficiencies of 0.86 ± 0.12 cm2 W−1 and 0.67 ± 0.10 cm2 W−1, respectively. These are the highest values ever reported for β-NaYF4:Er3+ under monochromatic excitation. The special characteristics of both the UC phosphor β-NaYF4:Er3+ and the PFCB matrix give rise to this outstanding property. Detailed power and time dependent luminescence measurements reveal energy transfer upconversion as the dominant UC mechanism
Causal Interfaces
The interaction of two binary variables, assumed to be empirical
observations, has three degrees of freedom when expressed as a matrix of
frequencies. Usually, the size of causal influence of one variable on the other
is calculated as a single value, as increase in recovery rate for a medical
treatment, for example. We examine what is lost in this simplification, and
propose using two interface constants to represent positive and negative
implications separately. Given certain assumptions about non-causal outcomes,
the set of resulting epistemologies is a continuum. We derive a variety of
particular measures and contrast them with the one-dimensional index.Comment: 20 pages, 3 figure
Children searching information on the Internet: Performance on children's interfaces compared to Google
Children frequently make use of the Internet to search for information. However, research shows that children experience many problems with searching and browsing the web. The last decade numerous search environments have been developed, especially for children. Do these search interfaces support children in effective information-seeking? And do these interfaces add value to today’s popular search engines, such as Google? In this explorative study, we compared children’s search performance on four interfaces designed for children, with their performance on Google. We found that the children did not perform better on these interfaces than on Google. This study also uncovered several problems that children experienced with these search interfaces, which can be of use for designers of future search interfaces for children
Interface Simulation Distances
The classical (boolean) notion of refinement for behavioral interfaces of
system components is the alternating refinement preorder. In this paper, we
define a distance for interfaces, called interface simulation distance. It
makes the alternating refinement preorder quantitative by, intuitively,
tolerating errors (while counting them) in the alternating simulation game. We
show that the interface simulation distance satisfies the triangle inequality,
that the distance between two interfaces does not increase under parallel
composition with a third interface, and that the distance between two
interfaces can be bounded from above and below by distances between
abstractions of the two interfaces. We illustrate the framework, and the
properties of the distances under composition of interfaces, with two case
studies.Comment: In Proceedings GandALF 2012, arXiv:1210.202
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