Quantitative modelling in cognitive ergonomics: predicting signals passed at danger

Abstract

This paper shows how to combine field observations, experimental data and mathematical modelling to produce quantitative explanations and predictions of complex events in human–machine interaction. As an example, we consider a major railway accident. In 1999, a commuter train passed a red signal near Ladbroke Grove, UK, into the path of an express. We use the Public Inquiry Report, ‘black box’ data, and accident and engineering reports to construct a case history of the accident. We show how to combine field data with mathematical modelling to estimate the probability that the driver observed and identified the state of the signals, and checked their status. Our methodology can explain the SPAD (‘Signal Passed At Danger’), generate recommendations about signal design and placement and provide quantitative guidance for the design of safer railway systems’ speed limits and the location of signals.

Practitioner Summary: Detailed ergonomic analysis of railway signals and rail infrastructure reveals problems of signal identification at this location. A record of driver eye movements measures attention, from which a quantitative model for out signal placement and permitted speeds can be derived. The paper is an example of how to combine field data, basic research and mathematical modelling to solve ergonomic design problems.     

Human factors data traceability and analysis in the European Community’s Major Accident Reporting System

This paper reports on human factors data traceability and analysis of the European Community’s Major Accident Reporting System (MARS). This is the main EU instrument to major accident data collection, analysis and dissemination for process industry according to the provisions of the Seveso II Directive. To date, the MARS database counts approximately 700 Seveso-type major events (November 2008). The MARS system is investigated in terms of human factors data and case studies exploring the relevance of human factors in accident events causation and identification issues. The human factors model and taxonomy as it is applied in the MARS system is reviewed. Criteria to enhance traceability and analysis about human related causes are then considered in detail. Finally, certain limitations affecting the system are pointed out. Findings are expected to favour future modelling and research efforts toward further MARS system improvements.     

基于系统调用的入侵检测系统研究

入侵检测是网络安全研究的热点技术之一，是新一代安全保障方案。该文实现了一种基于系统调用的异常入侵检测方法，使用系统调用作为输入，构建程序中函数的有限状态自动机，利用该自动机检测进程流程是否发生异常来确定是否发生了入侵。实验结果表明，该技术不仅能有效地检测出入侵行为，而且可以发现程序漏洞的位置，便于修改代码。     

Frequency slice algorithm for modal signal separation and damping identification

This paper focuses on modal signal separation and damping parameter identification by a new time–frequency analysis method. With the aid of the random decrement technique (RDT), an accurate estimation method is firstly introduced both in time and frequency domains for single modal damping identification. Next, the background of a new concept of frequency slice wavelet transform (FSWT) is revealed clearly. Then, some new properties of the FSWT are briefly discussed in contrast with the wavelet transform (WT). Based on the analysis of RDT and FSWT, a frequency slice algorithm (FSA) is designed for modal separation and parameter identification. The merits of FSWT and FSA with numerical simulations and experiments are demonstrated in this paper. We finally apply the proposed methods to analyze the free-decay responses (FDR) collected from a small laboratory bridge monitoring system (LBMS). Some conclusions are drawn that the RDT being used directly in FSWT domain can bring a good damping estimator. The FSA is not limited to FDR, and also can be used to random impacting response directly. FSWT itself is a new kind of good filter, and has high performance against noise. It is significant to get damping parameter with higher accuracy through modal separation by FSWT, and FSWT can be controlled adaptively in modal separation by dynamic scale method.     

FSA乘法器的设计与实现

鉴于有限状态机对于具有逻辑顺序和时序规律的事件能有清晰的描述,对传统乘法器设计进行改进。提出一种快速、低功耗的FSA乘法器设计。该设计使用VHDL语言进行实现,并在QuartusⅡ上通过了仿真。仿真结果表明基于状态机的与基于逻辑电路的设计相比,在运算过程中产生的功耗以及运算速度上有较大的改善。     

Mental causal models of incidents communicated in licensee event reports in a process industry

The present investigation describes some mental causal models used in incident reports. Some of the models (e.g., single-cause models) are simpler than others (e.g., causal-tree models). The models are also associated with different ways of explaining an incident or accident and with different recommendations for increasing the safety of a system. In study 1, incident reports from Swedish nuclear power plants known to use human or organisational factors were analysed. The analysis showed that the most frequent model was a simple single-cause model. Two-step models and more complex models were less frequent. Study 2 analysed all licensee event reports (including those reports not related to human organisational factors) from four reactors assessed by regulators during the year. The results showed that single-cause and two-step accident models were more frequent than more complex models. The analyses also revealed that different detection modes were related to different models.     

鱼群算法求解无人机任务规划问题

无人机任务规划问题是一个NP难问题,文中提出了一种带禁忌算子的鱼群算法对该问题进行求解.鱼群算法是在群体智能行为研究基础上提出的一种新型仿生优化算法,该算法根据"水域中鱼生存数目最多的地方一般就是该水域中富含营养最多的地方"这一特点来模拟鱼群的觅食行为以实现全局最优.文章在基本鱼群算法FSA的基础上,结合禁忌搜索的思想,对基本鱼群算法中的三种行为算子进行改进,在每种行为算子中增添对解领域的禁忌搜索规则,提出带禁忌算子的鱼群算法(FSAWTS).然后将该算法应用于无人机任务规划问题.仿真试验表明,与基本鱼群算法相比,改进后的鱼群算法能够更为有效得解决无人机任务规划问题.     

An observational comparison of the older and younger bus passenger experience in a developing world city

This study was an unobtrusive observational analysis of 333 older and younger bus passengers in Guadalajara, Mexico. A set of data were collected for each observed passenger, as well as more general observations related to driver behaviour, bus design and bus service characteristics. There were significant differences between older and younger passengers in terms of boarding and alighting times, use of handrails, seat location preferences, passenger stability and coping strategies in order to maintain postural stability. The conditions of travel are conducive to a poor passenger experience for the older passengers in particular. Although the problems may be attributed to bus design and driver behaviour typical of that in developing countries, they are also influenced by the wider transport infrastructure, and a lack of a regulatory regime which places drivers under time pressure and in direct competition with each other.

Practitioner Summary: Bus services must cater for all ages of passengers, including the elderly. This unobtrusive observational study investigated the passenger experience in a developing world city. Bus and wider service design were found to compromise the journey experience, with the older users being particularly negatively impacted. Design recommendations are provided.     

Dynamic Passenger Assignment for Major Railway Disruptions Considering Information Interventions

Passenger assignment models for major disruptions that require trains to be cancelled/short-turned in railway systems are rarely considered in literature, although these models could make a significant contribution to passenger-oriented disruption timetable design/rescheduling. This paper proposes a dynamic passenger assignment model, where the passengers who start travelling before, during and after the disruption are all considered. The model ensures that on-board passengers are given priority over waiting passengers, and waiting passengers are boarding under the first-come-first-serve rule. Moreover, the model allows information interventions by publishing information about service variations and train congestion at different locations with the aim of distributing passengers wisely to achieve less travel time increase due to the disruption. Discrete event simulation is adopted to implement the model, where loading/unloading procedures are realized and passengers re-plan their paths based on the information they receive. The model tracks individual travels, which helps to evaluate a disruption timetable in a passenger-oriented way.

     

Accimap and crowd flow in urban infrastructure: Case study of Elphinstone road railway station tragedy,Mumbai, India

The aim of this article is to show how Human Factors and Ergonomics (HFE) methods can be used to improve urban public infrastructure systems in densely populated countries, such as India. In this case, we use Accimap analysis with crowd flow approaches to inform safety and policy. We demonstrate the need for sociotechnical systemic safety by a case study of accident analysis of the Elphinstone Road railway station stampede. On September 29, 2017, the Elphinstone Road, Mumbai, India, railway platform bridge stampede killed at least 23 and injured 39 other commuters who traveled through the Mumbai Suburban railway. In this study, we understand the accident as it is presented in newspaper articles. We analyze the accident by a sociotechnical accident analysis method called the Accimap. The Accimap method helps by identification of various stakeholders and their interactions in the different levels of hierarchy in a sociotechnical system. This ensures moving away from individualistic and blame-based accounts of media reporting to a coherent sociotechnical account based on understanding the dynamics of the situation. The findings from the Accimap analysis identify the problem areas in the commuter transit system and provide recommendations. These recommendations range from commuter flow management to enforcement of rules for supporting pedestrian flow. The article concludes with an emphasis on the development of the sociotechnical dimension of public safety and infrastructure from a human factors perspective, above and beyond what is currently practiced in India.     

基于TRACEr失误辨识方法的电网调度人因风险认知分析

辨识和分析电网调度中的人为失误对于防范和控制人因风险、保障电网安全稳定运行至关重要。人为失误预测和确认方法在复杂系统的设计、评估和运行中已得到了广泛应用。结合电网调度业务知识和认知心理学模型,对认知差错追溯和预测技术(Technique for Ret-rospective and Predictive Analysis of Cognitive Errors,TRACEr)进行了分析和改进,研究了其在电网调度人为风险分析中的应用。运用提出的人为失误分析方法,对电网调度中的人因风险案例进行了分析,结果表明,基于TRACEr失误辨识方法能较为全面地分析电网调度员的人为失误,并为失误的补救和防范提供有效的改进措施。     

Motion sickness and motion characteristics of vessels at sea

Measurements of vessel motion and consequent seasickness amongst passengers have been made on six ships, two hovercraft and a hydrofoil. Data are presented for 20 029 passengers surveyed on 114 voyages involving 370?hours of motion recordings. Vomiting incidence and illness rating were found to be linearly related to the root-mean-square magnitude of the vertical z-axis acceleration. Sickness increased with increasing duration of exposure and a measure of motion ‘dose’ is examined as a convenient way of combining the variables of stimulus magnitude and duration. High frequency motion in hovercraft at about 0·6?Hz was found to be less provoking of sickness than similar magnitudes at lower frequencies. Motion in axes other than the vertical correlated less highly with sickness, although there was some intercorrelation between axes. The results presented enable predictions to be made of seasickness occurrence in marine vessels and other forms of transport where low frequency vertical oscillations are encountered.     

Chernobyl operators: criminals or victims?

The blame for the 1986 Chernobyl disaster has been variously attributed to the operating personnel, the plant management, the design of the reactor, and the lack of adequate safety information in the Soviet nuclear industry. This paper considers a number of design faults, operational shortcomings and human errors that combined in the accident. It examines the sequence of events leading up to the accident, design problems in the reactor and cooling rods, and the course of the accident itself. It considers the ergonomics aspects, and expresses the view that the main cause of the accident was inadequate human-machine interaction. Finally, it stresses the continuing inadequacies of the Soviet nuclear system, and emphasizes that unless the ergonomics lessons are fully learned, a similar disaster could still occur.     

Evolutionary design of discrete controllers for hybrid mechatronic systems

This paper investigates the issue of evolutionary design of controllers for hybrid mechatronic systems. Finite State Automaton (FSA) is selected as the representation for a discrete controller due to its interpretability, fast execution speed and natural extension to a statechart, which is very popular in industrial applications. A case study of a two-tank system is used to demonstrate that the proposed evolutionary approach can lead to a successful design of an FSA controller for the hybrid mechatronic system, represented by a hybrid bond graph. Generalisation of the evolved FSA controller to unknown control targets is also tested. Further, a comparison with another type of controller, a lookahead controller, is conducted, with advantages and disadvantages of each discussed. The comparison sheds light on which type of controller representation is a better choice to use in various stages of the evolutionary design of controllers for hybrid mechatronic systems. Finally, some important future research directions are pointed out, leading to the major work of the succeeding part of the research.     

LPDQ: A self-scheduled TDMA MAC protocol for one-hop dynamic low-power wireless networks

Current Medium Access Control (MAC) protocols for data collection scenarios with a large number of nodes that generate bursty traffic are based on Low-Power Listening (LPL) for network synchronization and Frame Slotted ALOHA (FSA) as the channel access mechanism. However, FSA has an efficiency bounded to 36.8% due to contention effects, which reduces packet throughput and increases energy consumption. In this paper, we target such scenarios by presenting Low-Power Distributed Queuing (LPDQ), a highly efficient and low-power MAC protocol. LPDQ is able to self-schedule data transmissions, acting as a FSA MAC under light traffic and seamlessly converging to a Time Division Multiple Access (TDMA) MAC under congestion. The paper presents the design principles and the implementation details of LPDQ using low-power commercial radio transceivers. Experiments demonstrate an efficiency close to 99% that is independent of the number of nodes and is fair in terms of resource allocation.     

Automatically composing and parameterizing skills by evolving Finite State Automata

We propose a robotics algorithm that is able to simultaneously combine, adapt and create actions to solve a task. The actions are combined in a Finite State Automaton whose structure is determined by a novel evolutionary algorithm. The actions parameters, or new actions, are evolved alongside the FSA topology. Actions can be combined together in a hierarchical fashion. This approach relies on skills that with which the robot is already provided, like grasping or motion planning. Therefore software reuse is an important advantage of our proposed approach. We conducted several experiments both in simulation and on a real mobile manipulator PR2 robot, where skills of increasing complexity are evolved. Our results show that (i) an FSA generated in simulation can be directly applied to a real robot without modifications and (ii) the evolved FSA is robust to the noise and the uncertainty arising from real-world sensors.     

Retrospective and prospective validity of aircraft accident risk indicators

Data from a national survey of pilots were used to examine the validity of measures for the prediction of aviation accidents that had occurred prior to the survey (retrospective analysis) and accidents that occurred after the survey (prospective analysis). Separate retrospective and prospective analyses were conducted, and 45 measures from the survey were found to be associated significantly with accident involvement in the retrospective analysis. However, only 13 of those 45 measures achieved significance in the prospective analysis. Most of the measures found to be significantly related to accident involvement concerned aviation exposure; the remaining measures related to pilots' perceived and actual level of caution. The study is unique in its use of a cohort design for the examination of aircraft accident risk prospectively, and the results suggest the need for caution in the interpretation of retrospective analyses in this research domain. Actual or potential applications of this research include the design of aviation safety programs and the design or interpretation of studies that address indicators of aircraft accident risk.     

On perspective,expertise and differences in accident analyses: arguments for a multidisciplinary integrated approach

This study draws attention to the importance of the fact that accident analyses, their conclusions and recommendations for improvements differ depending on the purpose of the analysis and the analyst's basic professional training. An accident in a hospital in which three patients died during dialysis was used as an illustrative example. The result of the legal analysis is presented first. Using this perspective, the cause of the accident was judged to be errors made by the chief nurse who was the only one who was found guilty of the deaths of three people. She was given a conditional prison sentence. The action taken at the hospital was to remove her from her job. Later, engineering and psychology experts were asked about how they attributed responsibility for the accident. Finally, the Accident Evolution and Barrier Function (AEB) method was also used to analyse the accident. This method models an accident as an interaction between technical and human factors systems. The results illustrated how the conclusions concerning action to avoid an accident in the future differed widely following a legal analysis and an AEB analysis of the same accident. The data also showed that the responsibility for the accident was attributed to one single person in the legal analysis but chiefly to other agents by engineers and psychologists. Analysts with a basic training in engineering tended to find relatively more human factors errors than technical errors in the AEB analyses. The number of acceptable solutions created to avoid future errors were related to the analyst's basic professional training and/or motivation, but the basic AEB modelling of the accident evolution was relatively less dependent on the basic professional training of the analysts and/or motivation. It was argued that a legal framework can be inefficient or even contraproductive in promoting improvements to the safety of complex integrated systems. This is particularly true if the convicted people are low in the hierarchy of an organization and cannot affect its future routines. It is also argued here that experts with different basic professional training should perform accident analyses jointly. This is because only then will there be an insightful coverage of the interactions between different systems as, for example, human factors and technological systems making it possible to increase the safety of a complex integrated system.     

An emergency aircraft evacuation simulation considering passenger emotions

The evacuation behavior of passengers was formulated as an autonomous agent and multi-agent model (AAMAS) evolving over a two-dimensional grid cell that represents aircraft cabins and passengers. In this model, the autonomous agents are initially placed in seat squares and move toward an emergency exit after an aircraft accident occurs. The autonomous agent mimics the behavior of passengers in the cabin, who must not only view their surroundings to collect the useful information but also select a route to an emergency exit. As the situation evolves, the agents feel the mental stress or strong fear or anxiety; thereby reacting unfavorably in the situation that they panic at. This abnormal evacuation behavior of panic agents generates time delays in the evacuation flow towards the exits. Therefore, such panic and its effect on evacuation behavior should be considered as an important factor in evacuation simulations. In this paper, it is supposed that the level of panic depends on three factors: remaining time, frequency of waiting and the difficulty of finding an exit. The dependencies of these factors on the time needed to complete an evacuation and the number of the panic agents in the aircraft were determined by the simulation. Considering the simulation results and situations of the actual aircraft accident “Garuda Indonesia Airways Accident”, it was possible to develop aircraft evacuation scenarios that considered passenger emotions.     

Foot surface area database and estimation formula

The purpose of this study is to establish a foot surface area (FSA) database and estimation formula based on 3-D foot scan data. For each gender, 135 subjects stratified in five statures and three body weights were drawn. The foot was measured using a high-resolution 3-D foot scanner, of which the precision and accuracy is within 1%. The FSA was computed by the triangular mesh summation method and five 1-D foot measurements were extracted automatically to be used as candidate estimators for FSA estimation formula. The results of the FSA measurements are tabulated on fifteen strata for the Male, the Female and the Total (the two genders combined). The comparison of these FSA measurements with previous studies shows that previous studies underestimated the FSA approximately 4.06% for the Total (for the Male, 6.93%; for the Female, 0.82%). Regression analyses using these five 1-D foot measurements were performed. The results show that foot-length and ball-girth are effective estimators of FSA for the total (FSA = 1.043 × foot-length × ball-girth, R² = 95.4%). A test on the necessity of gender-specific formula indicated that no gender-specific formula is needed, and the formula for the total is good for both genders.