Child pedestrian's exposure,accidents and behavior†

Empirical data on children's exposure, accidents and behavior are a necessary prerequisite for the selection of the most important educational objectives, as specified in a concrete form by a more theoretical “behavior requirements analysis”. In this report an attempt is made to summarize the most important empirical findings in this area within the framework of a pedestrian task analysis developed earlier. The report starts with the presentation of a conceptual framework relating the concepts exposure, behavior, conflicts and accidents. The last chapter mentions several research needs which are relevant for the identification and selection of educational objectives and for the evaluation of educational and environmental countermeasures.     

Fear and danger appraisals of a road-crossing scenario: a developmental perspective

Children's actual performance of visual timing task is possibly deficient, and road-crossing training programs focusing on visual timing elements result in questionable improvement in performance. The present study focused on conceptual, rather than perceptual, examination of the visual timing elements of distance and speed, as integrated into appraisals of risks related to a traffic scenario. Preschool children, third-grade children and adults appraised pedestrian fear and danger associated with four scenarios conceptually depicted using a table-top model. Each scenario described either a child or an adult pedestrian approached by a vehicle at various distances (near/far) and speeds (slow/fast). Results suggest that whereas the adult subjects integrated the danger and fear appraisals by giving separate weights to both distance and speed concepts, preschoolers failed to properly realize the danger associated with speed, and third-graders failed to integrate both concepts in their appraisals. In addition, children seem to be unaware of their underprivileged pedestrian status compared to adult pedestrians, as evidenced by similar appraisal patterns for both pedestrian age groups. The safety implications of these findings are discussed.     

Task-specific information for imaging system analysis

Imagery is often used to accomplish some computational task. In such cases there are some aspects of the imagery that are relevant to the task and other aspects that are not. In order to quantify the task-specific quality of such imagery, we introduce the concept of task-specific information (TSI). A formal framework for the computation of TSI is described and is applied to three common tasks: target detection, classification, and localization. We demonstrate the utility of TSI as a metric for evaluating the performance of three imaging systems: ideal geometric, diffraction-limited, and projective. The TSI results obtained from the simulation study quantify the degradation in the task-specific performance with optical blur. We also demonstrate that projective imagers can provide higher TSI than conventional imagers at small signal-to-noise ratios.     

Classification of human motions

Stages in the development of the classification for human motions are reviewed from the 17th century up to the present day, with special emphasis on the discrete events approach to the classification of human motions as advocated by the Gilbreths. It is put forward that this approach is inappropriate both from the psychological and the physiological view point; while at the same time it is emphasized that, although the therblig approach contributed significantly to the understanding of human motions and skills, nevertheless it may be more harmful than beneficial in the long run. The additive properties of the discrete events approach to the analysis of human motions are considered. Results of the investigations reported here suggest that, in the performance of repetitive tasks of the nature described here, the therblig times of the task are independent units within a work cycle, when analysed by means of 100 cycles. Thus, the times are additive in the mathematical sense, but when the same task is repeated only once, or a very few times, and analysed by single cycles, the therblig times form an integrated part of the entire work cycle and, therefore, their times are not additive in the mathematical sense.     

The effects of practice with MP3 players on driving performance

This study examined the effects of repeated iPod interactions on driver performance to determine if performance decrements decreased with practice. Nineteen younger drivers (mean age=19.4, range 18-22) participated in a seven session study in the University of Calgary Driving Simulator (UCDS). Drivers encountered a number of critical events on the roadways while interacting with an iPod including a pedestrian entering the roadway, a vehicle pullout, and a lead vehicle braking. Measures of hazard response, vehicle control, eye movements, and secondary task performance were analyzed. Increases in perception response time (PRT) and collisions were found while drivers were performing the difficult iPod tasks, which involved finding a specific song within the song titles menu. Over the course of the six experimental sessions, driving performance improved in all conditions. Difficult iPod interactions significantly increased the amount of visual attention directed into the vehicle above that of the baseline condition. With practice, slowed responses to driving hazards while interacting with the iPod declined somewhat, but a decrement still remained relative to the baseline condition. The multivariate results suggest that access to difficult iPod tasks while vehicles are in motion should be curtailed.     

Measurement: a beginner's guide

This paper provides an introduction to measurement theory for psychometricians. The central concept in measurement theory is that of a continuous quantitative attribute and explaining what measurement is requires showing how this central concept leads on to those of ratio and real number and distinguishing measurements from measures. These distinctions made, the logic of quantification is described with particular emphasis upon the scientific task of quantification, as opposed to the instrumental task. The position presented is that measurement is the estimation of the magnitude of a quantitative attribute relative to a unit and that quantification is always contingent upon first attempting the scientific task of acquiring evidence that the relevant attribute is quantitative in structure. This position means that the definition of measurement usually given in psychology is incorrect and that psychologists' claims about being able to already measure psychological attributes must be seriously questioned. Just how the scientific task of investigating whether psychological attributes are quantitative may be undertaken in psychology is then considered and the corollary that psychological attributes may not actually be quantitative is raised.     

The role of Body Mass Index in child pedestrian injury risk

The goal of the current investigation was to examine obesity as a potential risk factor for childhood pedestrian injury. A racially diverse sample of 7- and 8-year-old children completed a road-crossing task in a semi-immersive virtual environment and two pedestrian route selection tasks. Multiple linear regression analyses revealed that children with a higher Body Mass Index (BMI) waited less before crossing, had a smaller temporal buffer between themselves and oncoming traffic while crossing, and had more collisions with traffic. Girls were more cautious than boys when crossing the virtual roadway. Unlike the results from the virtual road-crossing task, BMI was not associated with risky route selection. Instead, race emerged as the strongest predictor, with African–American children selecting riskier routes for crossing. Together, these findings suggest overweight and obese children may be at increased risk for pedestrian injury. The discussion considers explanations for why obese children may exhibit riskier road-crossing behavior.     

Research of psychological characteristics and performance relativity of operators

Based on the working tasks of an operator being taken into full consideration in this paper, on the one hand the table of measuring psychological characteristics is designed through the selection of special dimensions; on the other hand the table of performance appraisal is drafted through the choice of suitable standards of an operator. The paper analyzes the results of two aspects, sets relevant nuclear power plant operators as the research objective, and obtains the psychological characteristics and performance relativity of operators. The research can be as important and applied reference for the selection, evaluation and use of operators.     

Task allocation in multiserver systems — A survey of results

Jobs consisting of one or more tasks arrive to a system comprising several servers, each with its own queue. Each task requires a single service at any of the servers, and a job completes service when all its constituent tasks have been serviced. Such models arise in the performance modelling of distributed computing systems, computer communication networks, and manufacturing systems. We survey the literature on this class of models. We classify jobs as being of one of three types: single tasks, multitask with precedence constraints, and multitask stream jobs. After surveying the optimal allocation problem for single task jobs, we discuss the results on the performance analysis and optimal allocation of tasks for the other two job types.     

认知老化视角下健康管理终端的多层次任务交互设计研究

目的 为提升老年群体居家场景下的慢病健康管理体验,聚焦认知老化现象,提升不同操作任务与认知需求的适配度,优化家庭健康管理终端产品交互设计。方法 通过文献查阅归纳老年人在认知活动中感知觉、智力、情感等相关特征要素,完成认知老化特征向设计指标映射;与此同时,引入SRK认知理论及其决策图,对设计载体完成关键任务分层;进一步将上述设计指标与任务层级作为模型变量,通过问卷数据分析,构建结构方程模型并获取分析结果,明确不同任务层级下的设计指标权重。结论 以家庭健康管理产品交互设计为例,通过结构方程模型分析,发现感官性体验对完成技能型任务具有显著正向影响、感官性体验和可用性体验对完成规则型任务具有显著正向影响、感官性体验和可用性体验及情感性体验均对知识型任务有显著正向影响,并获取每个体验维度中应重点关注的评价指标。实现从不同任务类型的角度分层次优化交互体验,为居家场景下的医疗健康管理产品适老化交互设计提供理论参考。     

虚拟现实中多通道信息呈现方式的认知负荷定量研究

目的 针对虚拟现实体验系统中的不同信息呈现方式,对使用者交互效率影响难以确定及量化的问题,进行定量研究。方法 通过搭建虚拟现实场景,以信息呈现通道的类别与数量作为变量,展开跟踪–检测响应双任务实验;通过记录任务行为数据中的跟踪误差和响应时间,以及生理数据中的瞳孔直径大小,分析并讨论在不同通道刺激影响因素下的实验中,任务绩效及眼动生理反应变化规律;同时结合主观负荷评价数据,建立了基于BP神经网络的多通道认知负荷模型,以认知负荷作为交互效率的综合评价指标,量化任务执行效率。结果 信息呈现的通道类别及其数量对任务效率均有显著的影响。结论 信息呈现通道数量与任务绩效及生理反应呈一定程度的正相关;多个任务使用相同通道呈现信息会损害所有任务的绩效,增加认知负荷。模型输出的负荷值与主观认知负荷评估值吻合较好,相对误差为8.2%,验证了其有效性。     

Modelling the effects of land use and temporal factors on child pedestrian casualties

This study investigates the suitability of land use variables in predicting the number of child pedestrian casualties; a subject of concern in Great Britain despite sustained improvements in road safety over the past decade. The relationship between land use and transport is used to establish a link between land use and child pedestrian travel; trip attractors and generators are considered as variables that lead child pedestrians to exposure to high risk environments. Casualty records for Newcastle upon Tyne are analysed to reveal trends of temporal variation of child pedestrian casualty numbers. Land use data is combined with the casualty data using GIS techniques to generate relevant inputs for the analysis. Six Generalized Linear Models (GLMs) are developed to analyse the association of child pedestrian casualty numbers and trip attractor land use types. Two are the main models; the first investigates all types of casualty data including slight, serious and fatal events and the second uses only KSI (Killed or Seriously Injured) data in the analysis. The other four models are developed to investigate the temporal variation of child pedestrian KSI and slight casualties over the day (school time and non-school time) and week (weekday and weekend). The results show that secondary retail and high density residential land use types are associated with all child pedestrian casualties. In addition, educational sites, junction density, primary retail and low density residential land use types are also associated with child casualties at different time periods of the day and week. The study findings are found to concur with the current child road safety policies in Great Britain and will, in fact, provide some guidance for local authorities to deliver successful child road safety audits.     

Children as pedestrians: Abilities and limitations†

The purpose of this paper is to present information on the feasibility of educational objectives in the field of traffic education for young children. In order to do so. it is necessary to answer four questions. These are: (1) Which behavior is desired? (2) Which functions and abilities are required for a safe performance of the tasks described in question 1? On the basis of existing literature a large number of necessary functions and abilities could be distinguished. These were combined into four groups related to: the perception of oncoming traffic, judgments to be made, the decision-making process and some additional tasks. (3) How do the necessary functions and abilities develop and at what age can they be used adequately? A survey of the traffic safety literature as well as the general child development literature forms the main part of this paper. (4) What implications does this development have for the leaching objectives? The results of the literature survey show, that a great lack of relevant research does exist. The relation of most studies with the actual traffic task is often a very weak one, even within the traffic safety literature. Only a few studies have been carried out in actual traffic situations and even in these studies the relation with crossing behavior has not been studied. Hence, it is not possible at present to give a detailed set of objectives feasible at a certain age. Although some objectives can be defined, much more research is necessary before final conclusions can be reached.     

Investigation of pedestrian crashes on two-way two-lane rural roads in Ethiopia

Understanding pedestrian crash causes and contributing factors in developing countries is critically important as they account for about 55% of all traffic crashes. Not surprisingly, considerable attention in the literature has been paid to road traffic crash prediction models and methodologies in developing countries of late. Despite this interest, there are significant challenges confronting safety managers in developing countries. For example, in spite of the prominence of pedestrian crashes occurring on two-way two-lane rural roads, it has proven difficult to develop pedestrian crash prediction models due to a lack of both traffic and pedestrian exposure data. This general lack of available data has further hampered identification of pedestrian crash causes and subsequent estimation of pedestrian safety performance functions. The challenges are similar across developing nations, where little is known about the relationship between pedestrian crashes, traffic flow, and road environment variables on rural two-way roads, and where unique predictor variables may be needed to capture the unique crash risk circumstances. This paper describes pedestrian crash safety performance functions for two-way two-lane rural roads in Ethiopia as a function of traffic flow, pedestrian flows, and road geometry characteristics. In particular, random parameter negative binomial model was used to investigate pedestrian crashes. The models and their interpretations make important contributions to road crash analysis and prevention in developing countries. They also assist in the identification of the contributing factors to pedestrian crashes, with the intent to identify potential design and operational improvements.     

Dynamic allocation of communicating tasks in computational grids

This paper studies task allocation in computational grids operating in a dynamic and uncertain environment. Computational grids consist of loosely coupled heterogeneous resources or agents with finite buffer capacities. These grids are primarily used to process large-scale applications consisting of several interdependent tasks. The task allocation problem is modeled as an infinite horizon Markov decision process, with the resource service times and the task arrivals following general probability distributions. We explicitly consider the communication cost between agents incurred in coordinating the execution of interdependent tasks. We show that a stationary optimal policy exists for this task allocation problem. Furthermore, we develop an action elimination procedure for reducing the complexity of computational methods in finding the optimal policy. We also present a real-time heuristic policy based on certain structural properties of the problem. Finally, computational results are presented that compare the performance of the heuristic policy with respect to other approaches for allocating tasks in the grid. Results from this paper are also applicable to the task allocation problem in manufacturing and service areas such as distributed design, project management and supplier coalitions.     

构建类教育玩具游戏任务的结构类型分析

目的 构建类教育玩具的游戏任务结构对学习功效的实现具有非常重要的影响。对构建类教育玩具游戏任务的结构类型进行分析,有利于厘清游戏任务的布局规律,为设计合理的、承载优良学习理念的构建类教育玩具提供了重要参考。方法 围绕目前主流的学习理论及其与学习工具之间的关系进行梳理,在此基础上对构建类教育玩具游戏任务的主要结构类型进行逐一分析。结论 在形式纷繁的构建类教育玩具的游戏任务中,其内部结构可依据相关学习理论的内涵归结为“单线型游戏任务结构”“多线归一型游戏任务结构”“多线开放型游戏任务结构”“建构型游戏任务结构”4种类型,它们分别适配于不同的游戏化学习目标,其价值可在构建类教育玩具的“外形”“连接”“功能”3个设计维度上得到集中体现。     

Performance evaluation for document analysis

A framework for evaluating the performance of a document analysis system is presented. This framework takes into account the task definition for the document analysis system, a data base on which that system is evaluated, the metrics used to evaluate performance, and the generalization of the results achieved beyond the confines of the test. Several recent significant efforts in evaluating document analysis systems are surveyed. How these efforts fit the general framework is discussed. The specific task that was evaluated, the data base used for the evaluation, and the generalization of the derived performance is presented. Most of these projects were designed for limited applications in which the translation of images of text into ASCII was the primary consideration. However, this is only part of what a document analysis system must often calculate. Other, less easily measured tasks, such as the subdivision of a document image into zones that represent regions of graphics, photographs, and text, must also be performed. Generally accepted solutions for measuring the performance of such tasks often do not exist. Several of them are mentioned as areas for future research. © 1996 John Wiley & Sons, Inc.     

Reliability of drivers in urban intersections

The concept of human reliability has been widely used in industrial settings by human factors experts to optimise the person-task fit. Reliability is estimated by the probability that a task will successfully be completed by personnel in a given stage of system operation. Human Reliability Analysis (HRA) is a technique used to calculate human error probabilities as the ratio of errors committed to the number of opportunities for that error. To transfer this notion to the measurement of car driver reliability the following components are necessary: a taxonomy of driving tasks, a definition of correct behaviour in each of these tasks, a list of errors as deviations from the correct actions and an adequate observation method to register errors and opportunities for these errors. Use of the SAFE-task analysis procedure recently made it possible to derive driver errors directly from the normative analysis of behavioural requirements. Driver reliability estimates could be used to compare groups of tasks (e.g. different types of intersections with their respective regulations) as well as groups of drivers’ or individual drivers’ aptitudes. This approach was tested in a field study with 62 drivers of different age groups. The subjects drove an instrumented car and had to complete an urban test route, the main features of which were 18 intersections representing six different driving tasks. The subjects were accompanied by two trained observers who recorded driver errors using standardized observation sheets. Results indicate that error indices often vary between both the age group of drivers and the type of driving task. The highest error indices occurred in the non-signalised intersection tasks and the roundabout, which exactly equals the corresponding ratings of task complexity from the SAFE analysis. A comparison of age groups clearly shows the disadvantage of older drivers, whose error indices in nearly all tasks are significantly higher than those of the other groups. The vast majority of these errors could be explained by high task load in the intersections, as they represent difficult tasks. The discussion shows how reliability estimates can be used in a constructive way to propose changes in car design, intersection layout and regulation as well as driver training.     

Typical pedestrian accident scenarios for the development of autonomous emergency braking test protocols

An increasing proportion of new vehicles are being fitted with autonomous emergency braking systems. It is difficult for consumers to judge the effectiveness of these safety systems for individual models unless their performance is evaluated through track testing under controlled conditions. This paper aimed to contribute to the development of relevant test conditions by describing typical circumstances of pedestrian accidents. Cluster analysis was applied to two large British databases and both highlighted an urban scenario in daylight and fine weather where a small pedestrian walks across the road, especially from the near kerb, in clear view of a driver who is travelling straight ahead. For each dataset a main test configuration was defined to represent the conditions of the most common accident scenario along with test variations to reflect the characteristics of less common accident scenarios. Some of the variations pertaining to less common accident circumstances or to a minority of casualties in these scenarios were proposed as optional or supplementary test elements for an outstanding performance rating. Many considerations are incorporated into the final design and implementation of an actual testing regime, such as cost and the state of development of technology; only the representation of accident data lay within the scope of this paper. It would be desirable to ascertain the wider representativeness of the results by analysing accident data from other countries in a similar manner.     

Analysis of scheduling algorithms for master–slave systems

The master-slave paradigm finds important applications in many industrial settings. In the master-slave model considered in this paper a set of jobs is to be processed by a system of processors. Each job consists of a preprocessing task, a slave task and a postprocessing task that must be executed in this order. The pre- and postprocessing tasks are to be processed by a master processor, whereas the slave task is processed by a slave processor. We consider three different specifications for the relative order of pre- and postprocessing tasks; namely order preserving sequences, reverse order sequences, and sequences where no order constraint is imposed. For the problem of minimizing makespan in master-slave systems with multiple masters, we develop heuristic algorithms with good bounded performance, for all three order specifications. Our computational results indicate that the average performance of our heuristics is near optimal. Furthermore, we identify the production environment and workload characteristics that favor each order specification.