39,821 research outputs found
Investigating Perceptual Congruence Between Data and Display Dimensions in Sonification
The relationships between sounds and their perceived meaning and connotations are complex, making auditory perception an important factor to consider when designing sonification systems. Listeners often have a mental model of how a data variable should sound during sonification and this model is not considered in most data:sound mappings. This can lead to mappings that are difficult to use and can cause confusion. To investigate this issue, we conducted a magnitude estimation experiment to map how roughness, noise and pitch relate to the perceived magnitude of stress, error and danger. These parameters were chosen due to previous findings which suggest perceptual congruency between these auditory sensations and conceptual variables. Results from this experiment show that polarity and scaling preference are dependent on the data:sound mapping. This work provides polarity and scaling values that may be directly utilised by sonification designers to improve auditory displays in areas such as accessible and mobile computing, process-monitoring and biofeedback
Predicting Big Bang Deuterium
We present new upper and lower bounds to the primordial abundances of
deuterium and helium-3 based on observational data from the solar system and
the interstellar medium. Independent of any model for the primordial production
of the elements we find (at the 95\% C.L.): and . When combined with
the predictions of standard big bang nucleosynthesis, these constraints lead to
a 95\% C.L. bound on the primordial abundance of deuterium: . Measurements of deuterium absorption in the
spectra of high redshift QSOs will directly test this prediction. The
implications of this prediction for the primordial abundances of helium-4 and
lithium-7 are discussed, as well as those for the universal density of baryons.Comment: Revised version of paper to reflect comments of the referee and reply
to suggestions of Copi, Schramm, and Turner regarding the overall analysis
and treatment of chemical evolution of D and He-3. Best-fit D/H abundance
changes from (2.3 + 3.0 - 1.0)x10^{-5} to (3.5 +2.7 - 1.8) x10^{-5}. See also
hep-ph/950531
Systematic derivation of a surface polarization model for planar perovskite solar cells
Increasing evidence suggests that the presence of mobile ions in perovskite
solar cells can cause a current-voltage curve hysteresis. Steady state and
transient current-voltage characteristics of a planar metal halide
CHNHPbI perovskite solar cell are analysed with a drift-diffusion
model that accounts for both charge transport and ion vacancy motion. The high
ion vacancy density within the perovskite layer gives rise to narrow Debye
layers (typical width 2nm), adjacent to the interfaces with the transport
layers, over which large drops in the electric potential occur and in which
significant charge is stored. Large disparities between (I) the width of the
Debye layers and that of the perovskite layer (600nm) and (II) the ion
vacancy density and the charge carrier densities motivate an asymptotic
approach to solving the model, while the stiffness of the equations renders
standard solution methods unreliable. We derive a simplified surface
polarisation model in which the slow ion dynamic are replaced by interfacial
(nonlinear) capacitances at the perovskite interfaces. Favourable comparison is
made between the results of the asymptotic approach and numerical solutions for
a realistic cell over a wide range of operating conditions of practical
interest.Comment: 32 pages, 7 figure
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