Roger S. Crouch

Agent-based simulation for large-scale emergency response: A survey of usage and implementation

When attempting to determine how to respond optimally to a large-scale emergency, the ability to predict the consequences of certain courses of action in silico is of great utility. Agent-based simulations (ABSs) have become the de facto tool for this purpose; however, they may be used and implemented in a variety of ways. This article reviews existing implementations of ABSs for large-scale emergency response, and presents a taxonomy classifying them by usage. Opportunities for improving ABS for large-scale emergency response are identified.

A multi-objective combinatorial model of casualty processing in major incident response

During the emergency response to mass casualty incidents decisions relating to the extrication, treatment and transporting of casualties are made in a real-time, sequential manner. In this paper we describe a novel combinatorial optimization model of this problem which acknowledges its temporal nature by employing a scheduling approach. The model is of a multi-objective nature, utilizing a lexicographic view to combine objectives in a manner which capitalizes on their natural ordering of priority. The model includes pertinent details regarding the stochastic nature of casualty health, the spatial nature of multi-site emergencies and the dynamic capacity of hospitals. A Variable Neighborhood Descent metaheuristic is employed in order to solve the model. The model is evaluated over a range of potential problems, with results confirming its effective and robust nature.

Agent-based simulation of emergency response to plan the allocation of resources for a hypothetical two-site major incident

During a major incident, the emergency services work together to ensure that those casualties who are critically injured are identified and transported to an appropriate hospital as fast as possible. If the incident is multi-site and resources are limited, the efficiency of this process is compromised as the finite resources must be shared among the multiple sites. In this paper, agent-based simulation is used to determine the allocation of resources for a two-site incident which minimizes the latest hospital arrival times for critically injured casualties. Further, how the optimal resource allocation depends on the distribution of casualties across the two sites is investigated. Such application supports the use of agent-based simulation as a tool to aid emergency response.

Observations on Mohr-Coulomb Plasticity under Plane Strain

Linear elastic-perfect plasticity using the Mohr-Coulomb yield surface is one of the most widely used pressure-sensitive constitutive models in engineering practice. In the area of geotechnical engineering, a number of problems, such as cavity expansion, embankment stability, and footing bearing capacity, can be examined using this model together with the simplifying assumption of plane strain. This paper clarifies the situation regarding the direction of the intermediate principal stress in such an analysis and reveals a unique relationship between hydrostatic pressure and the principal stress ratio for Mohr-Coulomb and Tresca perfect plasticity under those plane-strain conditions. The rational relationship and direction of the intermediate principal stress are illustrated through both material-point and finite-element simulations. The latter involves the analysis of a rigid strip footing bearing onto a weightless soil and the finite-deformation expansion of a cylindrical cavity.

Investigating the effect of overtriage on hospital arrival times of critically injured casualties during a major incident using agent-based simulation

This paper uses agent-based simulation to simulate the prehospital response to a hypothetical major incident in the UK. The rate of overtriage by the operational-level secondary triage officer is varied, and its effect on the latest arrival time of a critically injured casualty to hospital is modelled as a function of the number of ambulances involved in the response. Modelling such relationships could aid strategic-level planning for emergencies, by providing insight into how to compensate for the effect of overtriage.

Online optimization of casualty processing in major incident response: An experimental analysis

When designing an optimization model for use in mass casualty incident (MCI) response, the dynamic and uncertain nature of the problem environment poses a significant challenge. Many key problem parameters, such as the number of casualties to be processed, will typically change as the response operation progresses. Other parameters, such as the time required to complete key response tasks, must be estimated and are therefore prone to errors. In this work we extend a multi-objective combinatorial optimization model for MCI response to improve performance in dynamic and uncertain environments. The model is developed to allow for use in real time, with continuous communication between the optimization model and problem environment. A simulation of this problem environment is described, allowing for a series of computational experiments evaluating how model utility is influenced by a range of key dynamic or uncertain problem and model characteristics. It is demonstrated that the move to an online system mitigates against poor communication speed, while errors in the estimation of task duration parameters are shown to significantly reduce model utility.

The STORMI Scenario Designer: A program to facilitate setting up agent-based simulations of major incident emergency response

Compared to live exercises, agent-based simulation is an inexpensive method to perform ‘what-if’ style experiments of emergency response. However, the lack of a user-friendly interface often prevents such software being widely adopted by practitioners. This paper describes the STORMI Scenario Designer, a program designed specifically to facilitate practitioners in setting up agent-based simulations of emergency scenarios.

Simulating the spatial organization of the UK Ambulance Service at major incident sites

Documentation such as generic major incident plans and action cards describe how the UK Ambulance Service is to respond to major incidents, including how paramedics should organize themselves at the incident site. Towards the aim of testing existing procedures to hypothetical events in-silico, this paper proposes a way to simulate the on-site spatial organization of the UK Ambulance Service as part of an agent-based simulation of emergency response. The 2001 Selby train crash is used as a case study to demonstrate the approach.

A One-dimensional Analysis of the Distribution of Temperature, Stress and Strain in the co-axial Laser Cladding Process

The co-axial Laser Cladding (LC) is one of the most advanced surface treatment processes where generally a superior powder or wire material is deposited on the substrate to improve surface properties by using laser heat source. In this work, a physical model of the clad and the substrate has been presented. An attempt has been made to describe the simplified relation of temperature, stress and strain with time by using the established theoretical knowledge of generation of stress and strain after thermal treatment. The simplified relation of temperature, stress and strain with time has been explained with the help of schematic diagrams. The finding of this study will help to understand the temperature, stress and strain behaviour with time in the Laser Cladding process.

Modeling Uncertain and Dynamic Casualty Health in Optimization-Based Decision Support for Mass Casualty Incident Response

When designing a decision support program for use in coordinating the response to Mass Casualty Incidents, the modelling of the health of casualties presents a significant challenge. In this paper we propose one such health model, capable of acknowledging both the uncertain and dynamic nature of casualty health. Incorporating this into a larger optimisation model capable of use in real-time and in an online manner, computational experiments examining the effect of errors in health assessment, regular updates of health and delays in communication are reported. Results demonstrate the often significant impact of these factors.