A robust design to reduce variability in glass container inspection

This article presents research efforts made to assist a Fortune 500 glassmaker in reducing the variability of its automated visual inspection systems in assessing product quality. Through interviewing line workers, engineers and managers, and direct observations of the inspection process possible causes leading to large variability observed in the inspection process were identified. Responding to these findings, solutions related to equipment setup, job changes, and operational procedures were suggested in order to minimize the inspection process variations as well as to improve the replicability of the inspection stations. Additionally, a unique statistical experiment was conducted to analyze how three factors (namely, operator, defect size, and threshold value used) would affect the mean of the defective ratio. A robust design aiming at controlling these variations was then given to optimize the system's performance.     

A COMPARISON OF TWO SUBSIDIARY TASKS USED TO MEASURE FATIGUE IN CAR DRIVERS

Abstract

Car driving has been studied by combining it with a subsidiary task, performance on which is negatively correlated with the perceptual load imposed by changing conditions of traffic. The present experiment compares a subsidiary task which required almost continuous attention to an auditory display, and which involved memory spans of only 3 sec, with an alternative task which did not require continuous attention, but which involved memory spans of up to 55 sec. The former was found to have some advantages. This comparison was combined with a study of men engaged in 8-hour spells of car driving. Some explanations are offered for the finding that performance on the subsidiary tasks was better at the end of the work-spell than at the beginning.     

Day of the week lost time occupational injury trends in the US by gender and industry and their implications for work scheduling

While there is a growing body of research on the impact of work schedules on the risk of occupational injuries, there has been little investigation into the impact that the day of the week might have. The present research was completed to explore day of the week trends, reasons for such trends and the corresponding implications for work scheduling. Data for the number of injuries and illnesses involving days away from work (lost time; LT) in 2004 were provided by the US Bureau of Labor Statistics Office of Safety and Health Statistics. Data from the American Time Use Survey database were used to estimate work hours in 2004. From these two data sources, the rate of LT injuries and illnesses (per 200 000 work hours) by day of the week, industry sector and gender were estimated. The analysis revealed clear differences by day of the week, gender and major industry sector. Sundays had the highest rate overall – nearly 37% higher than the average of the remaining days, Monday to Saturday. Mondays had the next highest rate followed closely by Saturdays. This pattern was not the same for males and females. For males, Mondays had the highest LT rate (27% higher than the average of all other days) with all remaining days having essentially the same rate. For females, Sundays and Saturdays had much higher LT rates – 122% and 60% higher, respectively, than the average weekday rate. There were also differences by industry and differences between genders by industry. The present analysis suggests that several factors may be contributing to the weekend and Monday trends observed. Lower-tenured (and younger) workers on the weekends, lower female management/supervision and second jobs on the weekend seem to be contributors to the high Saturday and Sunday LT rates. Differences in day of the week employment by industry did not account for the trends observed. Fraud and overtime also could not be confirmed as contributing to these trends. Monday trends were more complex to explain, with possible explanations including non-work-related weekend injuries being reported on Mondays, soft-tissue symptoms becoming more noticeable on Mondays, greater Monday morning flexion risk and reduced supervision in the construction industry on Mondays. Interpretation of these trends and the implications for work scheduling are discussed.     

Influence of three principles of pacing on the temporal organisation of work during cyclic assembly and disassembly tasks

A study was conducted to investigate the influence of different approaches to arranging the pace and temporal organisation of repetitive assembly and disassembly tasks on both average performance and its variability and to compare assembly and disassembly times derived with psychophysical methods to a more traditional methods-time measurement (MTM) approach. The conditions studied were a traditional assembly line arrangement, where assemblies were started at a pace of 110 MTM (repeated on two occasions), a batch condition, where subjects were required to complete 36 assemblies within the total amount of time allowed at 110, MTM and a psychophysical condition, where subjects were allowed to choose their pace (repeated on two occasions). Overall, the results suggest that the mean time spent working in each cycle (the ‘on-time’) remained fairly constant across conditions, while the idle ‘off-time’ in between on-times was shorter and of less varied duration in the more autonomous batch and psychophysical conditions. During the second psychophysical (self-paced) condition, subjects completed a significantly higher number of assemblies than during the 110 MTM line condition. The higher pace was achieved through reduction in mean off-times and the potential implications for musculoskeletal risk are discussed.

Statement of Relevance: Higher levels of autonomy over work pace, which intuitively would be beneficial from an ergonomics standpoint, actually led to subjects selecting to organise work such that off-times (idle times) were reduced. In contrast, active ‘on’ times were not affected much by autonomy. These results point to a reason that piecework would be associated with increased risk for musculoskeletal disorders.     

HUMAN LIMITATIONS AND VEHICLE DESIGN∗

This paper contains a review of research on road vehicle design in relation to human physiological, anthropometric and psychological factors     

A question of our marketing or our preconceptions: Commentary on the paper ‘A strategy for human factors/ergonomics: developing the discipline and profession’

The present paper is a commentary on the recently published IEA strategy for human factors/ergonomics (Dul, J., et al. (2012), A strategy for human factors/ergonomics: developing the discipline and profession. Ergonomics, 55(4), 377–395). Two main issues that demand attention are: (i) the way others understand our profession and discipline, and (ii) the way we understand our profession and added value to industry. First, it is advocated that the discussion on the future of human factors/ergonomics (HFE) should be focused more on the quality of the delivered value of HFE and less on its visibility and marketing. Second, the three fundamental characteristics of HFE, as proposed in the report, are discussed and the consequences of this proposal are further developed. Arguments are put forward on the endemic epistemological vagueness within the discipline and on the optimistic definition of its aim. Finally, a proposal is made at the epistemological level, which challenges some established convictions of the discipline. It is advocated that such an epistemological evolution may be necessary if HFE is to make progress towards contributing to system performance.

Practitioner Summary: The paper is a commentary on the IEA strategy for human factors/ergonomics. Issues discussed are, the way others understand our profession and the way we understand our profession and added value to industry. Some of the established convictions of the discipline are challenged and proposals are made to overcome these.     

耦合渐变槽线天线及其和差波束的矩量法分析

本文阐述一种新型渐变槽线天线（ＴＳＡ）结构,耦合渐变槽线天线ＣＴＳＡ。单片的ＣＴＳＡ除可降低副瓣电平,提高增益,改善Ｅ面Ｈ面波束的对称外,还可通过与之配合的平面印刷奇偶模双工器馈电,同时实现和差波束。本文应用空间域矩量法（ＭｏＭ）建立了分析各种ＴＳＡ结构的数值模型;该方法在没有介质基片的情况下是严重的,本文集中讨论简化ＭｏＭ中阻抗矩阵积分运算的各种技术,有效地减小了计算量,并获得较高的精度。计算结     

声学综合无损检测技术

论述了检测复合材料和胶接结构不连续（缺陷）的新型多模综合无损检测技术。该技术以声与超声检测技术为基础,包含五种不同检测模式,用以检测复合材料与胶接结构的失粘、脱粘、分层、疏松、夹芯压皱及其他缺陷。它适用于复合材料与构件的制造、维修和使用现场。它的适用对象范围广泛,几乎覆盖了现有常用的复合材料和胶接结构。它的检测可靠性高,重复精度好。文章还讨论了组成多膜声学综合胶接检测仪的五种不同检测模式的原理,并从我们和国内外同行的大量实践经验出发,说明了综合无损检测技术的巨大发展前景。     

模块化多电平变换器优化调度调制策略研究

由于MMC电源的模块电容电压存在波动,一般认为它较为适用于定频运行。首先,定义了MMC电源的2种工作模式,即高效放电的工作模式和高效充电的工作模式;然后在此基础上提出了MMC电源的优化调度调制方法,该方法能够实现MMC变频变压运行时的低电容电压波动和高效控制;最后仿真结果验证了所提方法的有效性。