When it matters most: Collaboration between first responders in incidents and exercises

Inter‐organizational collaboration is increasingly a topic for studies into accidents and disasters as well as exercises. In this study, which is based on interviews with first responders, we compared perceived collaboration during an exercise with crisis work. The three organizations included in this study—fire department, police and ambulance services—perceived the investigated tunnel exercise completely different, ranging from harmonious interaction to power struggles between commanding officers, fragmented decision‐making and ambiguity. When comparing the exercise with an incident, we found that collaboration was more evident during incidents than in exercises. However, collaboration exercises appear to improve inter‐organizational collaboration by stimulating informal structures, practicing listening and delegating, getting to know one another and learning a common language.     

Using hash tables to manage the time-storage complexity in a point location problem: Application to explicit model predictive control

The online computational burden of linear model predictive control (MPC) can be moved offline by using multi-parametric programming, so-called explicit MPC. The solution to the explicit MPC problem is a piecewise affine (PWA) state feedback function defined over a polyhedral subdivision of the set of feasible states. The online evaluation of such a control law needs to determine the polyhedral region in which the current state lies. This procedure is called point location; its computational complexity is challenging, and determines the minimum possible sampling time of the system. A new flexible algorithm is proposed which enables the designer to trade off between time and storage complexities. Utilizing the concept of hash tables and the associated hash functions, the proposed method solves an aggregated point location problem that overcomes prohibitive complexity growth with the number of polyhedral regions, while the storage–processing trade-off can be optimized via scaling parameters. The flexibility and power of this approach is supported by several numerical examples.     

Cooperative path following of constrained autonomous vehicles with model predictive control and event‐triggered communications

We present a solution to the problem of multiple vehicle cooperative path following (CPF) that takes explicitly into account vehicle input constraints, the topology of the intervehicle communication network, and time‐varying communication delays. The objective is to steer a group of vehicles along given spatial paths, at speeds that may be path dependent, while holding a feasible geometric formation. The solution involves decoupling the original CPF problem into two subproblems: (i) single path following of input‐constrained vehicles and (ii) coordination of an input‐constrained multiagent system. The first is solved by adopting a sampled‐data model predictive control scheme, whereas the latter is tackled using a novel distributed control law with an event‐triggered communication (ETC) mechanism. The proposed strategy yields a closed‐loop CPF system that is input‐to‐state‐stable with respect to the system's state (consisting of the path following error of all vehicles and their coordination errors) and the system's input, which includes triggering thresholds for ETC communications and communication delays. Furthermore, with the proposed ETC mechanism, the number of communications among the vehicles are significantly reduced. Simulation examples of multiple autonomous vehicles executing CPF maneuvers in 2D under different communication scenarios illustrate the efficacy of the CPF strategy proposed.     

What can possibly go wrong? Anticipatory work in space operations

This paper explores how different forms of anticipatory work contribute to reliability in high-risk space operations. It is based on ethnographic field work, participant observation and interviews supplemented with video recordings from a control room responsible for operating a microgravity greenhouse at the International Space Station (ISS). Drawing on examples from different stages of a biological experiment on the ISS, we demonstrate how engineers, researchers and technicians work to anticipate and proactively mitigate possible problems. Space research is expensive and risky. The experiments are planned over the course of many years by a globally distributed network of organizations. Owing to the inaccessibility of the ISS, every trivial detail that could possibly cause a problem is subject to scrutiny. We discuss what we label anticipatory work: practices constituted of an entanglement of cognitive, social and technical elements involved in anticipating and proactively mitigating everything that might go wrong. We show how the nature of anticipatory work changes between planning and the operational phases of an experiment. In the planning phase, operators inscribe their anticipation into technology and procedures. In the operational phase, we show how troubleshooting involves the ability to look ahead in the evolving temporal trajectory of the ISS operations and to juggle pre-planned fixes along these trajectories. A key objective of this paper is to illustrate how anticipation is shared between humans and different forms of technology. Moreover, it illustrates the importance of including considerations of temporality in safety and reliability research.     

Design and analysis of gain-scheduled control using local controller networks

This paper describes a nonlinear control structure known as a local controller network. The structure consists of a weighted combination of a number of individual controllers, each of which is valid locally in the state space of the plant. Local controller designs are based upon local models valid in operating regimes which do not necessarily contain any physical equilibria. Consequently, the transient performance can be improved. Some 'scheduling' variables determine the current operating regime, and a validity function is assigned to each local controller. A 'feedforward' component may be used in each local controller in order to compensate directly for the operating-point-dependent model offsets. The application of the local controller network approach to a nonlinear control problem, that of longitudinal vehicle dynamics control, is described. A stability analysis for the discrete-time local controller network is given in this paper and the results are compared with known theoretical guidelines for related control approaches such as gain scheduling and feedback linearization.     

Lessons from Europe on quality improvement: report on the Velen Castle WHO meeting.

BACKGROUND: In conjunction with the German Ministry of Health, the European Regional Office of the World Health Organization (WHO/EURO) held a workshop, "Experiences with Quality Management in an International Context," at Velen Castle, Velen (Nordrhein-Westfalen), Germany, January 15-17, 1998. The approximately 50 participants were selected in part on the basis of recommendations of their respective countries' health ministries. IMPLEMENTATION AND EVALUATION OF QUALITY MANAGEMENT: Possible ways to introduce quality management ranged from introduction of specific process control projects to total quality management (TQM) and reengineering. STRATEGIES FOR IMPLEMENTING QUALITY MANAGEMENT: Working group sessions identified specific strategies for high-level managers, health care providers, and various kinds of consumers to facilitate quality management. For example, managers need to transmit a vision, create a quality management infrastructure, develop reporting structures, establish a system of incentives, and manage the hospital according to the principles of continuous improvement. QUALITY MANAGEMENT MODELS AND TOOLS: Hospitals and other health care providers in Sweden are testing various methods and systems to assess and improve their organizations' ability to meet patients' demands. Benchmarking is being used as a tool for quality management of diabetes care (DiabCare-France). The benchmarking data are processed centrally and made available to the health care providers in a user-friendly format for application to their own quality improvement processes. Clinical databases-registries containing process and outcome data for a well-defined patient population-can be used for quality and technology assessment, to answer questions of treatment effectiveness, and as an information tool. PRINCIPLES AND STRATEGIES FOR QUALITY MANAGEMENT AND DEVELOPMENT: Successful implementation of quality improvement benefits from local, professional, and national policies and objectives. A balance of incentives can reward efficiency or specific activities. Laws, rules, and regulations can be useful, especially if used sparingly. More education is needed at all levels of the health care system about how to understand and use information and information systems. Research is needed on what processes result in favorable outcomes. Despite optimism about the cost-saving potential of quality improvement efforts, many interventions are likely to be cost-effective without actually saving costs. Public release of performance data requires careful consideration, with participation of the professions.     

A method for mapping Australian woody vegetation cover by linking continental-scale field data and long-term Landsat time series

There is a significant need to provide nationwide consistent information for land managers and scientists to assist with property planning, vegetation monitoring applications, risk assessment, and conservation activities at an appropriate spatial scale. We created maps of woody vegetation cover of Australia using a consistent method applied across the continent, and made them accessible. We classified pixels as woody or not woody, quantified their foliage projective cover, and classed them as forest or other wooded lands based on their cover density. The maps provide, for the first time, cover density estimates of Australian forests and other wooded lands with the spatial detail required for local-scale studies. The maps were created by linking field data, collected by a network of collaborators across the continent, to a time series of Landsat-5 TM and Landsat-7 ETM+ images for the period 2000–2010. The fractions of green vegetation cover, non-green vegetation cover, and bare ground were calculated for each pixel using a previously developed spectral unmixing approach. Time series statistics, for the green vegetation cover, were used to classify each pixel as either woody or not using a random forest classifier. An estimate of woody foliage projective cover was made by calibration with field measurements, and woody pixels classified as forest where the foliage cover was at least 0.1. Validation of the foliage projective cover with field measurements gave a coefficient of determination, R²,of 0.918 and root mean square error of 0.070. The user’s and producer’s accuracies for areas mapped as forest were high at 92.2% and 95.9%, respectively. The user’s and producers’s accuracies were lower for other wooded lands at 75.7% and 61.3%, respectively. Further research into methods to better separate areas with sparse woody vegetation from those without woody vegetation is needed. The maps provide information that will assist in gaining a better understanding of our natural environment. Applications range from the continental-scale activity of estimating national carbon stocks, to the local scale activities of assessing habitat suitability and property planning.     

Fault‐Tolerant Control Allocation for Overactuated Nonlinear Systems

This paper addresses the problem of fault‐tolerant control allocation for input affine nonlinear systems. The proposed scheme is divided in three main tasks: fault detection and estimation using a nonlinear observer, fault isolation through a bank of unknown input observers with a resetting policy to reduce the effects of nonlinearities and control reconfiguration based on reduced order allocation. Analytical results regarding the isolability and reconfigurability of actuator faults are derived and a simulation example is used to illustrate the the proposed fault tolerant control methodology.