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

Monitoring the axial displacement of a high-rise building under construction using embedded distributed fibre optic sensors

The floor-to-floor axial shortening of vertical load-bearing elements is an important factor in the design and construction of high-rise buildings. Contractors need to allow for the expected final compression of columns and walls due to superimposed load, concrete creep and shrinkage, particularly when installing finishes and partitions in lower floors, while the building has not yet been completed. An added complication arises from the differential shortening between elements of different stiffness. This axial shortening is predicted by designers using empirical models, in advance of construction. However, in practice, the shortening at every level cannot be measured continuously using traditional surveying measurement techniques during construction. Therefore, a monitoring system using distributed fibre optic sensors (DFOS) measuring strain and temperature, is being installed during the construction of Principal Tower, a 50-storey reinforced concrete building in London. DFOS sensors are being embedded inside two columns and two walls as the construction progresses. Using the strain and temperature data acquired from this system, the axial deformation relative to the ground level can be calculated along the whole height of the completed elements, at any time during the construction. Thus, the engineers and contractors are able to verify their predictions and adjust their assumptions if necessary. A selection of the data acquired during the construction of the first 17 levels of the building is presented. These data have shown that the amount of shortening experienced by a member is influenced by the member’s stiffness and size. The monitoring data have also revealed that thermal movement has a significant effect on the overall axial displacement of the building

Stress analysis of a simplified compression plate fixation system for fractured bones

AbstractA three-dimensional finite element model was generated of a plexiglass tube with an attached six-hole stainless steel compression plate to study the mechanics of internal fixation of fractured long bones. To demonstrate the importance of the plate-bone interface, this interface was represented three different ways in the finite element model. A plated tube with a uniform transverse osteotomy gap was also examined to study the mechanics of plated fractured bones. To validate the model, the results for the intact plated tube were compared to composite beam theory and strain gauge data from an instrumented physical model. Applications of the finite element model data included the prediction of screw failure modes, plate-induced osteopenia, and multi-axial strains in an interfragmentary region. The addition of sliding motion between the plate and tube resulted in a deviation from composite beam theory and improved correspondence with strain gage data when compared to a model having the plate and tube securely bonded. Sliding motion resulted in a much smaller region of bone subjected to reduced axial stress levels, which may decrease the extent of plate-induced osteopenia. The complex nature of induced strains in an osteotomy gap was also demonstrated, along with the tendency for failure of the screws nearest the fracture site

Effect of illuminance and spectrum on peripheral obstacle detection by pedestrians

Obstacle detection is an important visual task for pedestrians. An experiment was carried out to measure the ability to detect peripheral obstacles under variations of illuminance and S/P ratio and with older and younger test participants. The LED array used in this work enabled S/P ratio to be varied whilst chromaticity was held constant. The tests employed a full scale model with dynamic fixation to better simulate pedestrian experience than in past work. Detection performance increased with illuminance, reaching a plateau at 2.0 lux. A higher S/P ratio improved obstacle detection but only at the lowest illuminance used in this study (0.2 lux). Older participants showed poorer obstacle detection performance than younger participants but again only at the lowest illuminance

Visual cues to interpersonal evaluations for pedestrians

Pedestrians need to be able to evaluate other people to support their feeling of safety. While past studies have thus investigated the degree to which road lighting supports facial identity and facial emotion evaluations, it is not yet known whether the face is the most important visual cue. Following a pilot study that indicated the importance of the ability to see the face and hands of other people, an experiment was conducted in which test participants evaluated safety when shown photographs of an approaching person in night-time scenes. These photographs displayed variations in the exposure or concealment of the face and hands. Two procedures were used, category rating and paired comparisons. The results suggest that the face is a more important visual cue than the hands for pedestrians’ evaluations of the intent of other pedestrians after dark

An approach to setting illuminances for subsidiary streets

Current recommendations for road lighting in residential areas may be based on inappropriate evidence. A first step in providing more appropriate evidence is understanding what important visual tasks pedestrians have to perform when walking. An experiment was carried out using eye - tracking equipment to identify significant aspects of pedestrian gaze behaviour during daylight hours and after - dark. A dual - task was used in which participants had to respond to an auditory stimulus at irregular times : s low respo nses were used as a guide for when attention was diverted from the response task to something in the visual environment. G aze behaviour at these times was categorised according to the significant object or area the pedest rian was looking at . Participants w ere more likely to look at other pedestrians or the path at critical times compared with other categories of objects, suggesting these are important visual tasks. Future research should examine how lighting affects our perception of other people and pathwa y characteristics, such as obstacles

What is the right light level for residential roads?

This article discusses the basis of light levels recommended for roads, in particular, that the evidence upon wh ich these are based has little basis in visual tasks or cost - benefit analysis. Eye - tracking studies have been carried out to identify the critical tasks, and performance of these tasks has been interpreted to identify threshold illuminances : these are a step towards better evidence for design criteria

USING ADJUSTMENT TO DEFINE PREFERRED ILLUMINANCES: DO THE RESULTS HAVE ANY VALUE?

Abstract The method of adjustment is examined as an approach to determine occupant illuminance preferences. From the results of previous studies using illuminance adjustment and recent studies performed purposely to investigate methodology, it is concluded that the method of adjustment has little value as a means of estimating the mean preferred illuminance. However, there is some evidence that when users are allowed to set their own light level that this enhances their satisfaction with the visual environment. Thus careful selection of the control variables (available range and initial value) offers the opportunity for reduced illuminances, and thus reduced energy consumption, whilst maintaining satisfaction

Road lighting for pedestrians: Effects of luminaire position on the detection of raised and lowered trip hazards

Previous work investigating how lighting enhances peripheral detection for pedestrians has tended to consider only raised hazards and lighting from a directly overhead source. An experiment was conducted to determine the extent to which variations in these parameters would influence the recommendations for optimal lighting. The results did not suggest a difference in the detection of raised and lowered trip hazards of the same change in vertical height relative to ground level. The results suggest that variation in light source position relative to the target does have a significant effect: To establish the implication of this requires further work to investigate detection under the least-favourable spatial arrangement