In highly social species such as humans, faces have evolved to convey rich information for social interaction, including expressions of emotions and pain 1–3. Two motor pathways control facial ...movement 4–7: a subcortical extrapyramidal motor system drives spontaneous facial expressions of felt emotions, and a cortical pyramidal motor system controls voluntary facial expressions. The pyramidal system enables humans to simulate facial expressions of emotions not actually experienced. Their simulation is so successful that they can deceive most observers 8–11. However, machine vision may be able to distinguish deceptive facial signals from genuine facial signals by identifying the subtle differences between pyramidally and extrapyramidally driven movements. Here, we show that human observers could not discriminate real expressions of pain from faked expressions of pain better than chance, and after training human observers, we improved accuracy to a modest 55%. However, a computer vision system that automatically measures facial movements and performs pattern recognition on those movements attained 85% accuracy. The machine system’s superiority is attributable to its ability to differentiate the dynamics of genuine expressions from faked expressions. Thus, by revealing the dynamics of facial action through machine vision systems, our approach has the potential to elucidate behavioral fingerprints of neural control systems involved in emotional signaling.
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•Untrained human observers cannot differentiate faked from genuine pain expressions•With training, human performance is above chance but remains poor•A computer vision system distinguishes faked from genuine pain better than humans•The system detected distinctive dynamic features of expression missed by humans
Bartlett et al. show that humans can fake expressions of pain such that others cannot detect their deceit at rates much better than guessing; however, a novel machine vision system that automatically decodes the dynamics of facial expression can successfully differentiate between genuine and faked pain expressions with 85% accuracy.
A spatial time-dependent reliability model is developed for a RC beam subject to corrosion-induced pitting corrosion, for shear and flexural limit states. The analysis considers the spatial and ...time-dependent variability of pitting corrosion, structural resistance and load effects. The amount of corrosion loss can significantly affect the mechanical behaviour of reinforcement, namely low corrosion loss can result in ductile yielding, whereas a higher corrosion loss can result in brittle fracture. The progression from ductile to brittle behaviour is spatially and time-dependent. To estimate how such phenomena affects structural reliability the structural resistance of reinforcement is modelled as either (i) perfectly ductile parallel system or (ii) perfectly brittle parallel system. It was found that the probability of failure assuming brittle reinforcement behaviour is up to 450% higher than assuming ductile behaviour.
Atmospheric CO2 is a major cause of reinforcement corrosion in bridges, buildings, wharves, and other concrete infrastructure in Australia, United States, United Kingdom and most other countries. The ...increase in CO2 levels associated with global warming will increase the likelihood of carbonation-induced corrosion. Moreover, temperature rises will increase corrosion rates. Clearly, the impact of climate change on existing and new infrastructure is considerable, as corrosion damage is disruptive to society and costly to repair. The paper describes a probabilistic and reliability-based approach that predicts the probability of corrosion initiation and damage (severe cracking) for concrete infrastructure subjected to carbonation and chloride-induced corrosion resulting from elevated CO2 levels and temperatures. The atmospheric CO2 concentration and local temperature and relative humidity changes with time over the next 100 years in the Australian cities of Sydney and Darwin are projected based on nine General Circulation Models (GCMs) under (i) high CO2 emission scenario, (ii) medium CO2 emission scenario, and (iii) CO2 emission reduction scenario based on policy intervention. The probabilistic analysis included the uncertainty of CO2 concentration, deterioration processes, material properties, dimensions, and predictive models. It was found that carbonation-induced damage risks can increase by over 400% over a time period to 2100 for some regions in Australia. Damage risks for chloride-induced corrosion increase by no more than 15% over the same time period due to temperature increase, but without consideration of ocean acidity change in marine exposure. Corrosion loss of reinforcement is not significant. The results were most sensitive to increases in atmospheric CO2.
•An approach is presented to estimate the probability of damage of RC columns subject to explosive blast loading.•Spatial variability of material and dimensional properties are considered.•The effect ...of blast load variability on structural reliability is investigated.•Monte Carlo simulation is used to derive Blast Reliability Curves.
Columns are the key load-bearing elements in frame structures and exterior columns are probably the most vulnerable structural components to terrorist attack. In this paper, a spatial reliability analysis is conducted to predict the damage for reinforced concrete (RC) columns subject to explosive blast loading. The spatial variability of material and dimensional properties of RC columns are modelled by stationary and non-stationary random fields. The variability of blast loading is also taken into consideration. Monte Carlo simulation and numerical methods are used to derive Blast Reliability Curves for RC columns under explosive loading for a number of terrorism threat scenarios, based on a high–fidelity physics-based computer programme LS-DYNA to estimate design and residual axial load-carrying capacity of RC columns. It was found that spatial variability has a significant effect on structural reliabilities and the spatial model will lead to more accurate predictions of damage and safety risks.
Over the years, power distribution systems have been vulnerable to extensive damage from hurricanes which can cause power outage resulting in millions of dollars of economic losses and restoration ...costs. Most of the outage is as a result of failure of distribution support structures. Over the years, various methods of strengthening distribution systems have been proposed and studied. Some of these methods, such as undergrounding of the system, have been shown to be unjustified from an economic point of view. A potential cost-effective strategy is targeted hardening of the system. This, however, requires a method of determining critical parts of a system that when strengthened, will have greater impact on reliability. This paper presents a framework for studying the effectiveness of targeted hardening strategies on power distribution systems subjected to hurricanes. The framework includes a methodology for evaluating system reliability that relates failure of poles and power delivery, determination of critical parts of a system, hurricane hazard analysis, and consideration of decay of distribution poles. The framework also incorporates cost analysis that considers economic losses due to power outage. A notional power distribution system is used to demonstrate the framework by evaluating and comparing the effectiveness of three hardening measures.
•Risk assessment of power distribution systems subjected to hurricanes is carried out.•Framework for studying effectiveness of targeted hardening strategies is presented.•A system reliability method is proposed.•Targeted hardening is cost effective for existing systems.•Economic losses due to power outage should be considered for cost analysis.
•Blast-resistant design using Ultra-high Performance Concrete (UHPC) columns.•Explosive ordnance and terrorism blast scenarios were considered.•Probability of major damage for a UHPC column varies ...from 1 × 10−2 to 1 × 10−5.•Decision metrics were target reliabilities and cost-benefit assessment.•Risk reducing benefit of blast-resistant UHPC columns can be considerable.
In conventional structural protective design against blast loads conservative structural designs are anticipated. However, unknown factors that include threat uncertainty, blast load variation, construction methods, material quality, etc., could impact the accuracy of assessment and design, sometimes even leading to an overestimation of structural capacity to explosive blast effects or an underestimation of actual blast pressures. In the present study, structural safety and reliability analyses of Ultra-high Performance Concrete (UHPC) columns under varying blast scenarios are performed. The variation in column dimensions, steel reinforcement, UHPC material strength, explosive range and mass, and numerical and blast load model errors are considered. The peak reflected pressure and impulse from the selected blast scenarios are derived based on variation in the explosive mass and standoff distance. Failure probabilities of columns made of this emerging high performance concrete material are then estimated. It was found that for a UHPC column designed for blast the probability of major damage given an explosive blast load varies from 1 × 10−2 to 1 × 10−5 for explosive ordnance and terrorism blast scenarios. This provides a reasonable margin of safety against major structural damage. It was also found that the risk reducing benefit of blast-resistant UHPC columns can be considerable.
•New stochastic model for casualty risks to fragmentation hazard.•Probabilistic models of fragment generation, trajectories, and human vulnerability.•Numerical simulations for fragment densities and ...casualty risks.•Safety evacuation distance obtained based on the casualty risks.
Fatalities and injuries are mainly attributed to primary fragmentation if accidental or malevolent detonation of high-explosive munitions occurs in an open space. This study aims to develop a simulation-based approach to assess individual casualty risks from primary fragments naturally generated by detonation of high-explosive munitions, which enables a stochastic characterization of fragment generation, trajectories, modelling uncertainties, and human vulnerability. The proposed method is demonstrated by a numerical example estimating the fatality and injury risks for an individual in a standing position exposed to the detonation of a single 105 mm projectile. The results suggest that, as expected, the individual fatality and injury risks decrease with an increasing stand-off distance. At a stand-off distance greater than 40 m, an individual is more likely to suffer injuries rather than fatality. The safety distance obtained from the present study is 97 m which is close to but less conservative than a safety distance of 104 m in existing literature and standards.
•Probabilistic modelling of construction defects in housing.•Bayesian approach combining expert opinion, HRA method and limited defect data.•Integration of construction defect model into wind ...fragility assessment.•Considerable effect of construction defects on roof cladding fragility is predicted.
Post-damage observations reveal that construction error is one of the major contributors to roof damage for houses subjected to extreme winds. In this study, a Bayesian approach was developed to probabilistically quantify the construction defect rates in roof connections, which enables a systematic integration of expert judgement, human reliability analysis (HRA) techniques and limited construction defect data. The reductions of uplift capacities for defective roof connections were also probabilistically modelled based on experimental evidence and engineering judgement. The developed construction defect model was incorporated in a reliability-based fragility method to assess the wind damage to metal roof cladding and timber roof trusses for contemporary houses in non-cyclonic regions of Australia. It was found that, the effects of construction defects are significant for the predicted roof cladding fragility, whereas for roof truss fragility, such effects are lower.
The reaction of Americans to the terrorist attacks of September 11, 2001, has been massively disproportionate to the actual threat posed by al-Qaida either as an international menace or as an ...inspiration or model for homegrown amateurs. An examination of the activities of international and domestic terrorist "adversaries" reveals that exaggerations and distortions of the threat have inspired a determined and expensive quest to ferret out, and even to create, the nearly nonexistent. The result has been an ill-conceived and remarkably unreflective effort to react to an event that, however tragic and dramatic in the first instance, should have been seen to be of only limited significance at least after a few years. Not only has the terrorism delusion had significant costs, but the initial alarmed perspective has been so internalized that anxieties about terrorism have persisted for more than a decade despite exceedingly limited evidence that much fear is justified.
•Utilization of the Bayesian probability, utility and decision analysis.•Consistent assessment of information acquirement and physical mitigation strategies.•Identification of optimal, significant ...and efficient strategies before implementation.
This paper describes the assessment of the cost efficiency of risk mitigation strategies for terrorist attacks with Improvised Explosive Devices (IEDs) for an iconic bridge structure. The assessment is performed with a decision theoretical framework building upon very recent advances in the COST Action TU1402 on Quantifying the Value of Structural Heath Monitoring. The decision scenario is formulated for a decision maker constituting an authority responsible for the societal safety of the infrastructure and consequently the direct risks for the infrastructure owner and the indirect risk due to fatalities and importance of the infrastructure are considered. The mitigation strategies are classified within the decision theoretical context as prior analyses for the assessment of protection strategies and as control strategies requiring a pre-posterior decision analysis. The identification of efficient risk mitigation strategies is based (1) on the risk and expected cost based optimization of actions and information and their combination before implementation, (2) on quantifying and ensuring the significance in risk and expected cost reduction and (3) on quantifying and ensuring a high probability of cost efficiency. These criteria, i.e. the optimality, significance and efficiency ensure the performance of the strategies at the decision point in time before implementation. It is found that the strategies are relying on the identification of the threat level and that control strategies are in favor as their significance and probability of efficiency are higher and their costs are adjustable. However, for high threat levels, both the bridge protection strategies and control strategies are cost efficient.
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