How practice produces suboptimal heuristics that render backup instruments ineffective

The operation of machines typically requires attention to instruments that signal the state of the machine. One safeguard against primary instrument malfunction is to provide backup instruments, but this works only if the operators react to malfunction by switching attention to the backups. Little is known about the effect of negative outcomes or feedback on allocation of attention to backup instruments. Four experiments demonstrated that prior practice causes operators of a simulated machine to adapt to instrument malfunction by changing to a suboptimal decision rule rather than by reallocating attention to a different set of instruments. This fallacy appears linked to the operators' failures to notice feedback that they should switch during the simulations and operators' failures to correctly interpret outcome feedback following the simulations. The results raise theoretical questions and warn interface designers not to overrate backup instruments.     

密度加权平均中间算子及其在多属性决策中的应用

针对已有的信息集结算子没有考虑属性信息分布疏密程度的情况,研究了一维数据聚类的问题,并给出一种一维聚类的方法.在此基础上,开发了密度加权平均（DWA）中间算子,并将该算子与已有的5种信息集结算子进行合成,得到的合成算子兼顾了多种算子的特点.最后通过一个算例验证了DWA算子及合成算子的一些新颖的特征.     

基于隧道技术的客户端策略路由研究

目前很多校园、小区、企业单位的网络,除了接入一条主干的ISP运营商提供的网络外,还同时接入多个不同的ISP运营商提供的网络.其目的是根据收费情况的不同最大程度地节省开销外,还使得原来比较脆弱的单一出口有了备份,不会因为一个ISP发生故障而中断和因特网的连接.但是,这种多出口网络体系结构必须解决策略路由的配置问题.探讨了如果通过隧道技术实现在客户端进行策略路由的方法.     

Effective attention allocation behavior and its measurement: a preliminary study

In general, evaluation of human–machine interface design remains a challenging task. Specifically, there remains a lack of method for tracking effective human operator's attention. This paper presents a study aimed at devising such a method. This method is based on a combination of operators' eye movement and hand movement behaviors. The eye movement reflects the operators' cognitive process and attention allocation, while the hand movement reflects the operators' physical action, which is the result of a cognitive process. Effectiveness of that piece of cognition (eye movement) can therefore be evaluated based on the result of an action (hand movement). The said measure, which may be called the hand–eye measure, is examined for its sensitivity to a good or poor operation behavior and patterns that are further correlated to the operator's behavior and performance. At present, the patterns across the whole operation period are explored. A reference system is employed to validate the hand–eye measure.     

Prevalence of data operators' musculoskeletal symptoms during the workday and workweek

. The aim of this report, which is part of a study on the factors of mental load in office work, was to determine whether 30 data operators' musculoskeletal symptoms varied during the workday and workweek. An ergonomic survey was also carried out to find measures to improve the workstations and to motivate the operators to recognize problem areas. The results showed that all musculoskeletal symptoms increased during the workday, but symptoms in the neck and shoulders most of all. There were no differences in the prevalences of symptoms between the beginning and the end of the workweek. In response to the questions on mental-load factors, operators described their work as not mentally demanding but as very pressing at times. They felt they received insufficient feedback and that their work was not appreciated by the work organization. These results led to the following recommendations: job rotation; increased feedback;, more instruction on how to adjust the worksite. Excercises for relaxation and the improvement of muscle awareness were also recommended.     

数控机床维修与维护技术

随着数控机床在各行业生产中的应用日益广泛,数控机床的维护与维修已成为保障生产、提高效率的关键。本文通过一些具体的故障实例,来介绍在数控机床故障处理方面的一些思路和方法。     

面向流式数据处理系统的高效故障恢复方法

针对流式数据处理系统Flink无法高效处理单点故障的问题,提出了一种基于增量状态和备份的故障容错系统Flink+。首先,提前建立备份算子和数据通路;然后,对数据流图中的输出数据进行缓存,必要时使用磁盘;其次,在系统快照时进行任务状态同步;最后,在系统故障时使用备份任务和缓存的数据恢复计算。在系统实验测试中,Flink+在无故障运行时没有显著增加额外容错开销;而在单机和分布式环境下处理单点故障时,与Flink系统相比,所提系统在单机8任务并行度下故障恢复时间减少了96.98%,在分布式16任务并行度下故障恢复时间减少了88.75%。实验结果表明,增量状态和备份方法一起使用可以有效减少流式系统单点故障的恢复时间,增强系统的鲁棒性。     

Postural modifications of VDU operators wearing bifocal spectacles

This paper describes the postural changes experienced by presbyopic operators of VDU workstations while wearing a pair of bifocal spectacles. All operators reported in this paper had suffered neck and back aches, in addition to generalised problems of asthenopia, while using the VDU workstation. The ages of the operators ranged between 47 and 58 years. The operators' head movements, in looking from the keyboard to the screen, were two to three times greater when bifocal spectacles were worn compared with specially prescribed single-vision occupational spectacles. There were also greater movements in the flexion of the wrist and elbow while using bifocal spectacles and looking from the keyboard to the screen. There was no relationship between the amount of head movement and the position of the bifocal reading segment with respect to the operators' pupil. It was concluded that the symptoms reported by these presbyopic operators were due to static loading of the muscles in the neck and back, induced by the use of bifocal spectacles.     

Safety implications of cultural and cognitive issues in nuclear power plant operation

This research project was designed to investigate cultural and cognitive issues related to the work of nuclear power plant operators during their time on the job in the control room and during simulator training (emergency situations), in order to show how these issues impact on plant safety. The modeling of the operators work deals with the use of operational procedures, the constant changes in the focus of attention and the dynamics of the conflicting activities. The paper focuses on the relationships between the courses of action of the different operators and the constraints imposed by their working environment. It shows that the safety implications of the control room operators' cognitive and cultural issues go far beyond the formal organizational constructs usually implied. Our findings indicate that the competence required for the operators are concerned with developing the possibility of constructing situation awareness, managing conflicts, gaps and time problems created by ongoing task procedures, and dealing with distractions, developing skills for collaborative work.     

Technological coupling, job characteristics and operators' well-being as moderated by desirability of control

This study proposes that the nature of Automated Manufacturing Technology (AMT)-as reflected in the degree of 'technological coupling' and as perceived by shop floor operators in terms of new job control characteristics (timing and method control, monitoring and problem solving demand, production responsibility)-affects operators' psychological well-being (satisfaction and mental health). The study sample consisted of 216 operators of AMT equipment. Findings indicate that technological coupling is negatively related to the job characteristics of timing and method control, and to psychological well-being variables. Operators' satisfaction is positively related to problem solving, production responsibility and timing and method control. Mental health is negatively related to production responsibility. Implications for job redesign and employees selection to AMT work units are discussed. Yet, results indicate that operators' response to technological coupling is contingent upon their desirability of control (DC). For operators with low DC (as opposed to high DC) coupling conditions did not make any difference in psychological well-being.     

扩大内桥接线备自投和TV并列回路的分析

介绍扩大内桥接线备自投逻辑,分析TV解列失败导致备自投拒动的原因,提出解决方法,并总结相应的防范措施。     

面向OpenStack/Ceph的虚拟机备份系统研究

针对OpenStack面临的虚拟机容灾备份问题,提出了一种基于Ceph存储快照的虚拟机容灾备份系统,备份时对虚拟机存储在Ceph中的磁盘生成快照,再根据备份要求计算有效数据或者变化数据,保存虚拟机的配置信息以及磁盘数据,恢复时自动创建相同配置的虚拟机并将当前快照点的磁盘数据恢复到该虚拟机中.实验表明,该方法比OpenStack的快照备份方法能有效节省备份时间和存储空间,并且可以实现后者不具有的增量备份、多磁盘备份等功能.     

Trust, control strategies and allocation of function in human-machine systems.

As automated controllers supplant human intervention in controlling complex systems, the operators' role often changes from that of an active controller to that of a supervisory controller. Acting as supervisors, operators can choose between automatic and manual control. Improperly allocating function between automatic and manual control can have negative consequences for the performance of a system. Previous research suggests that the decision to perform the job manually or automatically depends, in part, upon the trust the operators invest in the automatic controllers. This paper reports an experiment to characterize the changes in operators' trust during an interaction with a semi-automatic pasteurization plant, and investigates the relationship between changes in operators' control strategies and trust. A regression model identifies the causes of changes in trust, and a 'trust transfer function' is developed using time series analysis to describe the dynamics of trust. Based on a detailed analysis of operators' strategies in response to system faults we suggest a model for the choice between manual and automatic control, based on trust in automatic controllers and self-confidence in the ability to control the system manually.     

Cost effectiveness of ergonomic redesign of electronic motherboard

A case study to illustrate the cost effectiveness of ergonomic redesign of electronic motherboard was presented. The factory was running at a loss due to the high costs of rejects and poor quality and productivity. Subjective assessments and direct observations were made on the factory. Investigation revealed that due to motherboard design errors, the machine had difficulty in placing integrated circuits onto the pads, the operators had much difficulty in manual soldering certain components and much unproductive manual cleaning (MC) was required. Consequently, there were high rejects and occupational health and safety (OHS) problems, such as, boredom and work discomfort. Also, much labour and machine costs were spent on repairs. The motherboard was redesigned to correct the design errors, to allow more components to be machine soldered and to reduce MC. This eliminated rejects, reduced repairs, saved US dollars 581495/year and improved operators' OHS. The customer also saved US dollars 142105/year on loss of business.     

Spreadsheet calculations for the machine interference queueing model

The machine interference queueing model has numerous applications in different areas. Yet it is seldom used due, mainly, to the complexity of the associated calculations. In this paper, a simple and easy-to-implement spreadsheet application of the model is presented. This application calculates state probabilities and mean values for key parameters: machine utilization, operators’ load and system throughput. The application is parametric in the numbers of machines and operators, mean time between (machine) failures, and mean service time. This facilitates model analysis and turns the spreadsheet application into a powerful tool for analysis, design and decision support.     

Joint coverage and link utilization for fast IP local protection

To mitigate the impact of failures, many IP Fast Local Recovery (IPFLR) schemes have been proposed to reroute traffic in the events of failures. However, the existing IPFLR schemes either aimed to find the alternate backup routes to protect failures, or focused on balancing the traffic load routed on the backup routes. Furthermore, in Internet, flows are often managed by shortest path routing, and therefore purely determining the backup routing paths is not sufficient in protecting the error-prone networks. In this paper, we propose a Simulated Annealing based Load balancing and Protection (SALP) scheme to determine link weights for balancing link utilization in the non-failure state and simultaneously construct backup routing tables for protecting any single link failure in IP networks. In our proposed scheme, the two most significant issues, (1) load balancing and (2) coverage, are jointly considered to recover the network operation from single link failures. In the proposed scheme, upon a failure, only the nodes adjacent to a failure are activated to divert affected traffic to backup paths without disturbing regular traffic. Numerical results delineate that the proposed scheme achieves high coverage rate and load balancing at the expense of slightly increasing the entries of backup routing table.     

An ergonomics study on compatibility of controls of overhead cranes in a heavy engineering factory in West Bengal

Ergonomics studies, on the machine control and the resultant movements of the cabins and the hooks in 51 electric overhead travelling cranes in a heavy engineering factory, showed that control-movement compatibility is absent in most of the cranes. Also, the layout of the groups of controls and the orientations of each of the individual controls with respect to the operators' seats varied from one crane to another. As the operators were shifted from one crane to another every week, there was a high chance of making mistakes during moving the controls, which might have resulted in severe accidents, especially during periods of high workload. A number of low-cost ergonomics solutions have been recommended to minimize these problems.     

Building Edge-Failure Resilient Networks

We consider the design of resilient networks that are fault tolerant against link failures. Resilience against link failures can be built into the network by providing backup paths, which are used in the eventuality of an edge failure occurring on a primary path in the network. We consider several network design problems in this context; these problems are motivated by the requirements of current high-speed optical networks. In all the following problems the objective is to provide resilience in networks while minimizing the cost incurred. The main problem under consideration in this paper is that of backup allocation: this problem takes as its input an already provisioned primary network and a parameter k, and allocates backup capacity on the edges of the underlying network so that all the demand can be routed even in the presence of k edge failures. We also consider a variant of this problem where the primary network has a tree topology, and it is required that the restored network retains a tree topology. We then address the problem of simultaneous primary and backup allocation: we are given specifications of the traffic to be handled, and the goal is to provision both the primary as well as the backup network. Finally, we investigate a single-commodity problem motivated by a pragmatic scenario in which the primary network is not known in advance and demands between source--sink pairs arrive online.     

三维水声传感器网络中多径容错路由协议研究

针对三维水声传感器网络中因节点或链路故障导致的路由性能低下问题,提出一种多径容错路由协议。该协议通过为每个节点设计一种称为后备箱的数据结构,并利用节点的路由表和后备箱构造主后备链路和辅后备链路,以便在节点或链路发生故障的情况下修复路由路径,确保数据的正常传输。仿真结果表明,多径容错路由协议可以减小节点或链路故障对数据传输率和网络吞吐量的影响。