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

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

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

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

Cu-doped ceria: Oxygen vacancy formation made easy

DFT + U calculations of Cu-doped bulk ceria are presented. The first oxygen vacancy in Cu-doped ceria forms almost spontaneously and the second vacancy is also easily created. Whether zero, one or two oxygen vacancies, the Cu dopant is in the form Cu(+II), and prefers to be 4-coordinated in a close to planar structure. Charge compensation, structural relaxation and available Cu–O states all play roles in lowering the O vacancy formation energies, but to different degrees when the first and second oxygen vacancies are formed. The Cu-doped ceria(1 1 1) surface system behaves in a similar fashion

Relative concentration and structure of native defects in GaP

The native defects in the compound semiconductor GaP have been studied using a pseudopotential density functional theory method in order to determine their relative concentrations and the most stable charge states. The electronic and atomic structures are presented and the defect concentrations are estimated using calculated formation energies. Relaxation effects are taken into account fully and produce negative-U charge transfer levels for VP and PGa. The concentration of VGa is in good agreement with the results of positron annihilation experiments. The charge transfer levels presented compare qualitatively well with experiments where available. The effect of stoichiometry on the defect concentrations is also described and is shown to be considerable. The lowest formation energies are found for PGa +2 in p-type and VGa −3 in n-type GaP under P-rich conditions, and for GaP −2 in n-type GaP under Ga-rich conditions. Finally, the finite size errors arising from the use of supercells with periodic boundary conditions are examined

Diffusion mechanism of Zn in InP and GaP from first principles

The diffusion mechanism of Zn in GaP and InP has been investigated using first-principles computational methods. It is found that the kickout mechanism is the favored diffusion process under all doping conditions for InP, and under all except n-type conditions for GaP. In n-type GaP the dissociative mechanism is probable. In both p-type GaP and InP, the diffusing species is found to be Zni+2. The activation energy for the kickout process is 2.49 eV in GaP and 1.60 eV in InP, and therefore unintentional diffusion of Zn should be a larger concern in InP than in GaP. The dependence of the activation energy both on the doping conditions of the material and on the stoichiometry is explained, and found to be in qualitative agreement with the experimentally observed dependencies. The calculated activation energies agree reasonably with experimental data, assuming that the region from which Zn diffuses is p type. Explanations are also found as to why Zn tends to accumulate at pn junctions in InP and to why a relatively low fraction of Zn is found on substitutional sites in InP

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

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

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

Point defects on the (110) surfaces of InP, InAs and InSb: a comparison with bulk

The basic properties of point defects, such as local geometries, positions of charge-transfer levels, and formation energies, have been calculated using density-functional theory, both in the bulk and on the 110 surface of InP, InAs, and InSb. Based on these results we discuss the electronic properties of bulk and surface defects, defect segregation, and compensation. In comparing the relative stability of the surface and bulk defects, it is found that the native defects generally have higher formation energies in the bulk. From this it can be concluded that at equilibrium there is a considerably larger fraction of defects at the surface and under nonequilibrium conditions defects are expected to segregate to the surface, given sufficient time. In most cases the charge state of a defect changes upon segregation, altering the charge-carrier concentrations. The photo-thresholds are also calculated for the three semiconductors and are found to be in good agreement with experimental data