112 research outputs found

    Does expression choice affect the analysis of light spectrum and facial emotion recognition?

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    Facial emotion recognition has been used as a representative pedestrian activity in studies examining the effect of changes in road lighting. Past studies have drawn conclusions using results averaged across performance with the six universally recognised expressions. This paper asks whether expression choice matters. A reanalysis of past data for each unique expression does not suggest a change in the conclusion that facial emotion recognition is not significantly affected by the spectral power distribution of the lighting

    Varying facial expressions in studies of interpersonal judgements and pedestrian lighting

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    This paper reports two analyses carried out to investigate the influence of facial expression choice in work exploring interpersonal judgements and lighting for pedestrians. An experiment was conducted to compare performance on a facial recognition task using target and reference images of either the same or different expressions: these data demonstrated that matching with different expressions led to a significant reduction in recognition. Regarding the results from previous studies of facial emotion recognition, a post-hoc analysis was carried out to draw conclusions from analysis of individual expressions rather than the collation of all six expressions: it was concluded that these data were consistent for all individual expressions

    Investigating the chromatic contribution to recognition of facial expression

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    A pedestrian may judge the intentions of another person by their facial expression amongst other cues and aiding such evaluation after dark is one aim of road lighting. Previous studies give mixed conclusions as to whether lamp spectrum affects the ability to make such judgements. An experiment was carried out using conditions better resembling those of pedestrian behaviour, using as targets photographs of actors portraying facial expressions corresponding to the six universally recognised emotions. Responses were sought using a forced-choice procedure, under two types of lamp and with colour and grey scale photographs. Neither lamp type nor image colour was suggested to have a significant effect on the frequency with which the emotion conveyed by facial expression was correctly identified

    The Structure of the [Zn_In - V_P] Defect Complex in Zn Doped InP

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    We study the structure, the formation and binding energies and the transfer levels of the zinc-phosphorus vacancy complex [Zn_In - V_P] in Zn doped p-type InP, as a function of the charge, using plane wave ab initio DFT-LDA calculations in a 64 atom supercell. We find a binding energy of 0.39 eV for the complex, which is neutral in p-type material, the 0/-1 transfer level lying 0.50 eV above the valence band edge, all in agreement with recent positron annihilation experiments. This indicates that, whilst the formation of phosphorus vacancies (V_P) may be involved in carrier compensation in heavily Zn doped material, the formation of Zn-vacancy complexes is not. Regarding the structure: for charge states Q=+6 to -4 the Zn atom is in an sp^2 bonded DX position and electrons added/removed go to/come from the remaining dangling bonds on the triangle of In atoms. This reduces the effective vacancy volume monatonically as electrons are added to the complex, also in agreement with experiment. The reduction occurs through a combination of increased In-In bonding and increased Zn-In electrostatic attraction. In addition, for certain charge states we find complex Jahn-Teller behaviour in which up to three different structures, (with the In triangle dimerised, antidimerised or symmetric) are stable and are close to degenerate. We are able to predict and successfully explain the structural behaviour of this complex using a simple tight binding model.Comment: 10 pages text (postscript) plus 8 figures (jpeg). Submitted to Phys. Rev.

    Exceeding Energy Consumption Design Expectations

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    Operational building performance often fails to meet that predicted at the design stage by as much as two to three times. Many reasons for this difference have been identified and widely reported, however, the problem still continues to occur. A case study new 'energy efficient' fully air conditioned office building has been monitored since occupation in June 2010 to observe the difference between operational energy consumption and design targets. In the first full year of operation (2011) the building consumed 208.7 kWh m-2 yr-1, 83% of the expected energy consumption (250 kWh m-2 yr-1). This dropped further to 176.1 kWh m-2 yr-1 in 2012 (70% below expected). Factors affecting building energy consumption have been discussed and appraised in respect to the case study building. Recommendations have been made for successfully meeting future building energy design targets. A number of energy saving technologies have been installed during the monitoring period such as LED lighting, voltage optimisation and thin client. An appraisal of these is also given, along with the performance of the photovoltaic panels and rainwater harvesting in place from the outset

    Single and Many Particle Correlation Functions and Uniform Phase Bases for Strongly Correlated Systems

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    The need for suitable many or infinite fermion correlation functions to describe some low dimensional strongly correlated systems is discussed. This is linked to the need for a correlated basis, in which the ground state may be postive definite, and in which single particle correlations may suffice. A particular trial basis is proposed, and applied to a certain quasi-1D model. The model is a strip of the 2D square lattice wrapped around a cylinder, and is related to the ladder geometries, but with periodic instead of open boundary conditions along the edges. Analysis involves a novel mean-field approach and exact diagonalisation. The model has a paramagnetic region and a Nagaoka ferromagnetic region. The proposed basis is well suited to the model, and single particle correlations in it have power law decay for the paramagnet, where the charge motion is qualitatively hard core bosonic. The mean field also leads to a BCS-type model with single particle long range order.Comment: 23 pages, in plain tex, 12 Postscript figures included. Accepted for publication in J.Physics : Condensed Matte

    Direct observation of electron doping in La0.7Ce0.3MnO3 using x-ray absorption spectroscopy

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    We report on a X-ray absorption spectroscopic (XAS) study on a thin film of La0.7Ce0.3MnO3, a manganite which was previously only speculated to be an electron doped system. The measurements clearly show that the cerium is in the Ce(IV) valence state and that the manganese is present in a mixture of Mn2+ and Mn3+ valence states. These data unambiguously demonstrate that La0.7Ce0.3MnO3 is an electron doped colossal magnetoresistive manganite, a finding that may open up new opportunities both for device applications as well as for further basic research towards a better modelling of the colossal magnetoresistance phenomenon in these materials.Comment: 4 pages, 3 figures, revised versio

    Giant Thermoelectric Effect from Transmission Supernodes

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    We predict an enormous order-dependent quantum enhancement of thermoelectric effects in the vicinity of a higher-order `supernode' in the transmission spectrum of a nanoscale junction. Single-molecule junctions based on 3,3'-biphenyl and polyphenyl ether (PPE) are investigated in detail. The nonequilibrium thermodynamic efficiency and power output of a thermoelectric heat engine based on a 1,3-benzene junction are calculated using many-body theory, and compared to the predictions of the figure-of-merit ZT.Comment: 5 pages, 6 figure

    Resonant transmission through an open quantum dot

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    We have measured the low-temperature transport properties of a quantum dot formed in a one-dimensional channel. In zero magnetic field this device shows quantized ballistic conductance plateaus with resonant tunneling peaks in each transition region between plateaus. Studies of this structure as a function of applied perpendicular magnetic field and source-drain bias indicate that resonant structure deriving from tightly bound states is split by Coulomb charging at zero magnetic field.Comment: To be published in Phys. Rev. B (1997). 8 LaTex pages with 5 figure

    The number of transmission channels through a single-molecule junction

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    We calculate transmission eigenvalue distributions for Pt-benzene-Pt and Pt-butadiene-Pt junctions using realistic state-of-the-art many-body techniques. An effective field theory of interacting π\pi-electrons is used to include screening and van der Waals interactions with the metal electrodes. We find that the number of dominant transmission channels in a molecular junction is equal to the degeneracy of the molecular orbital closest to the metal Fermi level.Comment: 9 pages, 8 figure
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