Analysis of information exchange activities to actualize and validate situation awareness during shift changeovers in nuclear power plants

Shift work situations occur in almost all safety‐critical organizations, and the investigations of some catastrophes like Chernobyl, Exxon Valdez, and the Gol/Legacy mid‐air collision indicated that shift work information exchange played an important role during the evolution of the situation before the accidents. Inadequate communications during shift changeovers challenged operators' work in the moments that preceded these accidents, because they got inadequate information about the current situation. Our research focuses on the information exchange activities (verbal, written, and nonverbal) of nuclear power plant control operators during shift changeovers. Our aim is to investigate how verbal exchanges and other representations enable operator crews to share information regarding the events that occurred in the previous shift to achieve adequate situation awareness. Our findings indicated the importance and richness of the information exchange during the shift changeover process to update and validate individual and collective situation awareness, showing that information adequately shared enables the ad hoc configurations of regulation loops and a safer use of simplified strategies that can be understood and be validated by other operators, reducing the occurrence of cognitive overloads and contributing to the construction of a common cognitive ground that enhances system resilience. © 2010 Wiley Periodicals, Inc.     

Effects of time pressure and communication environment on team processes and outcomes in dyadic planning

An experiment compared dyadic performance in a radio communication and a more sophisticated communication environment to face-to-face (FtF) meetings. Thirty-six dyads, working under low or high time-pressure conditions, needed to combine information and to produce a written plan. Teams working in the sophisticated communication environment collaborated from separate locations over a networked computer system allowing them to share a note-taking program, work in parallel, and exchange in real-time audio as well as video. Results revealed detrimental effects of time pressure on both team processes and outcomes, and supported our hypothesis that distributed teams can perform as well as FtF teams. No differences were found between FtF teams and teams working in the sophisticated communication environment on process and outcome measures, except for the quantity of performance: The sophisticated communication environment enabled distributed teams to work on the task more rapidly than their FtF counterparts. Radio teams produced plans of lower quality and were less satisfied with the quality of their planning process than FtF teams.     

Designing better shift systems

The results of some intervention studies on the effects of the change from weekly rotating to quicker rotating shift systems are presented. Consequently, the following recommendations for the design of shift systems according to physiological, psychological and social criteria are discussed: (1) Nightwork should be reduced as much as possible. If this is not possible, quickly rotating shift systems are preferable to slowly rotating ones. Permanent nightwork does not seem to be recommendable for the majority of shiftworkers. (2) Extended workdays (9-12 hours) should only be contemplated when the nature of work and the workload are suitable for extended working hours, and the shift system is designed to minimize the accumulation of fatigue and toxic exposure is limited. (3) An early start for the morning shift should be avoided. Flexible working time arrangements can be achieved in all shift systems. The highest flexibility is possible in the so-called 'time autonomous groups'. (4) Quick changeovers (e.g. from night shift to afternoon shift on the same day) should be avoided. The number of consecutive working days should be limited to five-seven. Every shift system should include some free weekends with at least two consecutive days off. (5) The forward rotation (phase delay, clockwise rotation: morning/evening/night shift) would seem to be most preferred.     

The design of shift systems

All shift systems have advantages and drawbacks. There is no single ‘optimum shift system’ which can be used in industry or commerce at all work places. However, there are shift systems which are more favourable, and others which are less favourable, in the context of physiological, psychological, and social recommendations for the design of shift systems. This article discusses the following recommendations:

(1) Nightwork should be reduced as much as possible. If this is not possible, quickly rotating shift systems are preferable to slowly rotating ones. Permanent nightwork does not seem to be advisable for the majority of shiftworkers.

(2) Extended workdays (9-12 h) should only be contemplated, if the nature of work and the workload are suitable; the shift system is designed to minimize the accumulation of fatigue; there are adequate arrangements for cover of absentees; overtime will not be added; toxic exposure is limited; and if it is likely that a complete recovery after work and a high acceptance of the working time arrangement are possible.

(3) An early start for the morning shift should be avoided. In all shiftsystems flexible working time arrangements- are realizable. The highest flexibility is possible in ‘time autonomous groups’.

(4) Quick changeovers (e.g., from night to afternoon shift at the same day or from afternoon to morning shift) must be avoided. The number of consecutive working days should be limited to 5-7 days. Every shift system should include some free weekends with at least two successive full days off.

(5) The forward rotation of shifts (phase delay, clockwise rotation) would seem to be recommendable at least in continuous shift systems.

Besides the design of a shift system, implementation strategy is of particular importance for the acceptance of the shift system.     

An algorithm for shift scheduling which considers circadian principles

The principles of circadian rhythms in human beings have been applied to devise a methodology for scheduling shift work in a hospital unit which is operating under several important constraints. Considered here are time off between shifts, number of consecutive work days, number of distinct shifts in any two calendar weeks, number of shifts per week and special staffing for informational and training meetings. It is shown how the method of Czeisler et al. (1982) can be adapted for the more constrained work environment. A set of evaluation scales for circadian theory violations is devised and applied to an example from Togus VA Hospital. Results include the actual schedules together with evaluations on three different aspects of circadian theory: length of cycle on a single shift, rotation involving night shifts and rotation not involving night shifts. Improvements of each of these evaluations with respect to previously published results are obtained.     

Temporal aspects in crisis management and its implications on interface design for situation awareness

Temporality should be considered in the design of information technology support for crisis management (CM), both because crises are dynamic events and because time is a part of situation awareness (SA). This study has used group interviews to explore how different temporal aspects of CM can be considered in CM design and how they can influence crisis managers SA. A prototype and a scenario were used as mediating materials. The result consists of two parts. The first part is comprised of the participants?? reflections on how timelines can be used to display information in CM information systems. According to the participants, timelines should present: deadlines, information sent to the public, incoming and outgoing information, an overview of where the current activities belong in the CM process and what has been going on since the last shift during shift changes. Timelines should not only display the listed information, but also provide functionality for adjusting the timescale so that information can be presented in alternative temporal perspectives. The second part of the result contains several obstacles that might influence the crisis managers?? ability to obtain SA. Obstacles elicited from the group discussions are: information overflow, fast changes of SA due to incoming information, difficulties to share SA with actors outside the CM centre, forgetting things that need attention and that SA depends on the quality of incoming information. The two parts of the result have been compiled into six design principles for how temporality can be considered in CM systems in order to support SA.     

Alertness of night nurses: two shift systems compared

The alertness of hospital trainee nurses during their night shift work was assessed by recording performance at night on an arousal-sensitive unprepared simple reaction time task. One group carried out a number of separate weeks on night shift throughout their three-year course. Here performance fell from first to seventh day of the week on night shift, implying progressive sleep deprivation. Another group covered their night work by a single three-month 'permanent' night shift of four (or three) nights on and three (or four) days off each week. Here initial performance level fell by the 45th night but had returned to normal by the last (90th) night. In both systems individuals varied considerably in their ability to maintain performance during sustained night work. These results strengthen the case for permanent night shifts, with careful selection of personnel, as a means of organizing night nursing in hospitals.     

考虑知识溢出下产业集群创新网络协同知识创造决策分析

协同知识创造对于企业维持和获取竞争优势具有重要作用,但是知识外溢会对企业的竞争力造成威胁,从而使企业在创新网络协同知识创造决策时陷入两难困境.鉴于此,通过构造由一个核心企业和n个从属企业组成的创新网络在协同知识创造过程中知识投入决策Stackelberg博弈模型,引入知识内溢系数、私有知识、知识外溢损失等变量,探讨知识溢出下,网络成员的知识投入决策和知识产出分配问题.研究结果表明:核心企业与从属企业的知识投入比和知识投入总量与协同知识创造绩效和知识内溢收益之和有关,而与私有知识外溢的损失无关;集群创新网络协同知识创造机制得以运行的条件是核心企业的知识创造收益(即知识创造绩效与知识内溢收益之和)足够大;核心企业的知识投入比与其边际收益和知识内溢系数正相关,与从属企业的边际收益和知识内溢系数负相关;协同知识创造过程中从属企业会根据其边际收益和知识内溢系数按比例分配知识的投入比.     

Influence on working hours among shift workers and effects on sleep quality – An intervention study

The aim of the present intervention study was to examine if increased influence on working hours among shift workers led to better sleep quality.391 employees were categorized into groups based on the performed activities: High (self-rostering), moderate (education and/or policy for working hours), and low intensity intervention (meetings and discussions) and reference. Sleep quality was assessed by Karolinska Sleep Questionnaire (KSQ) at baseline and follow-up (12 months). To elucidate the process of the intervention interviews were conducted.Influence on one’s own working hours increased only in the high intensity group (p < 0.001). No effects of interventions on sleep quality were observed. Thus, sleep quality was not improved by increasing work time influence in the present group of Danish elder care workers. This was partly due to program failure (failed intervention), but may also be due to other factors such as few participants working night and few working full time.     

Analyzing sharing strategies for finite buffer memory in a router among outgoing channels

We propose a model for a transit node in a data transmission network that distributes the incoming flow over several outgoing directions. We study the influence of the quality of communication channels, distribution of the shares of incoming traffic over outgoing directions, and strategies for dividing a limited buffer memory in the transit node among queues to outgoing communication channels on the throughput of the network fragment with incoming and outgoing interfaces of varying performance.     

限制链路数量对无线传感器网络寿命的影响

由于传感器节点能量受限,如何优化无线传感器网络(WSN)寿命是一项重要任务。借助混合二元线性规划(MBLP)框架,对限制传入/传出链路数量的WSN寿命影响进行了研究。利用MBLP最大化WSN寿命,并给出对应约束条件;通过线性网络拓扑结构,分析了节点数量、节点面积对WSN寿命的影响。性能分析表明,如果传入/传出链路数量至少为3时,网络寿命降低小于1.0%,从而进一步证明了分割流量为三部分足以平衡传感器节点间的能耗。     

The impact of shift and night work on health

Shift work, in particular night work, can have a negative impact on health and well-being of workers as it can cause: (a) disturbances of the normal circadian rhythms of the psychophysiological functions, beginning with the sleep/wake cycle; (b) interferences with work performance and efficiency over the 24 hour span, with consequent errors and accidents; (c) difficulties in maintaining the usual relationships both at family and social level, with consequent negative influences on marital relations, care of children and social contacts; (d) deterioration of health that can be manifested in disturbances of sleeping and eating habits and, in the long run, in more severe disorders that deal prevalently with the gastrointestinal (colitis, gastroduodenitis and peptic ulcer), neuro-psychic (chronic fatigue, anxiety, depression) and, probably, cardiovascular (hypertension, ischemic heart diseases) functions. Besides, shift and night work may have more specific adverse effects on women's health both in relation to their particular hormonal and reproductive function, and their family roles. It has been estimated that about 20% of all workers have to leave shift work in a very short time because of serious disturbances; those remaining in shift work show different levels of (mal)adaptation and (in)tolerance, that can become more or less manifest in different times, and with different intensity. In fact, the effects of such stress condition can vary widely among the shift workers in relation to many 'intervening variables' concerning both individual factors (e.g. age, personality traits, physiological characteristics), as well as working situations (e.g. work loads, shift schedules) and social conditions (e.g. number and age of children, housing, commuting).     

Reducing understaffing and shift work with Temporal Profile Optimization (TPO)

The ergonomic quality of shift schedules can be improved by reducing time periods with understaffing (resulting in work-pressure, poor quality, etc.) and evening, night and/or weekend work.Improving the quality of forecasts regarding future workforce requirements as well as the optimization of work processes by moving as much work as possible to more suitable time zones are two approaches to this.We introduce and propose Temporal Profile Optimization (TPO) as a systematic approach to question the demand as well as its translation to workforce planning. Temporal profiles describe the number of employees needed over time (e.g. for different days of the week, times of day, for different calendar days) as well as the shift-times and staffing levels planned to meet this workforce demand.With Temporal Profile Forecasts we introduce a forecasting method that is based on time-stamped historical data and methodologically supplements traditional time series models like SARIMA in many ways. With Temporal Profile Reengineering we use systematic and often participatory methods from business process reengineering to identify moveable work and streamline the load lines by (re-)distributing movable work such that shifts and schedules are improved.The approach is illustrated along two business cases. Using TP-Forecasts for air traffic controllers increased forecasting accuracy whereby a different shift design was possible resulting in 3–4% less shift work. In a warehouse of an Austrian freight carrier a TP-Forecast together with TP-Reengineering helped to rearrange work processes such that the resulting workforce requirements curve had a more even form. This allowed for shorter shifts than before (thereby decreasing overtime).Experiences made so far stress the potential of Temporal Profile Optimization.     

Tolerance of shift work

This study aimed to explore criteria for shift work tolerance and to investigate the relationships between personality traits and states and shift work tolerance. Eighty-nine policemen and police women completed a questionnaire, once during consecutive night shifts and again during rotating shifts, and their responses were used to assess anxiety, emotional control, positive and negative affect, health complaints, sleep quality, difficulties in social and domestic life, and perceptions about shift work. Both the criteria for tolerance and the relationship between tolerance and personality varied according to shift type. Night shift tolerance involved four factors--somatic health, flexibility, sleep and sleep need--while rotating shift tolerance involved three factors--somatic health, flexibility and fatigue. Tolerance of shift work was associated with anxiety, repressive emotional style and mood. During night shifts, anxiety was the most influential personality factor for the somatic health and sleep dimensions of shift tolerance. During rotating shifts, positive and negative moods, rather than trait personality factors, were important predictors of the somatic health and fatigue shift tolerance dimensions. These results suggest a mechanism for more effective matching of workers to suitable shift schedules.     

An exact algorithm for a Vehicle-and-Driver Scheduling Problem

This article introduces a combinatorial optimization problem that consists of assigning tasks to machines and operators, and sequencing the tasks assigned to each one. Two configurations exist. Machines alternate configurations, while the operators must start and finish the process in the same configuration. Moreover, machines and operator have limited capacities. The sequencing of the tasks must guarantee that each one is performed by a machine and an operator at the same time, and it is determined in order to minimize an overall cost function. Two critical aspects of the problem are the need of synchronizing the machine and the operator performing each task, and the need of minimizing the changeovers, which are pairs of tasks done consecutively by the same machine but by different operators. The problem is modeled as a vehicle routing problem with two types of vehicles and with two depots. We propose a mixed integer programming formulation, and introduce valid inequalities to strengthen its linear programming relaxation. We describe separation routines for these inequalities and design a branch-and-cut algorithm for the problem. The algorithm is tested on a set of benchmark instances showing that it is able to solve to optimality instances with up to 50 customers.     

Participants’ personal note-taking in meetings and its value for automatic meeting summarisation

This paper reports the results of novel quantitative research on multiple people’s personal note-taking in meetings with the long-term aim of aiding the creation of innovative meeting understanding applications. We present three experiments using a large number of group meetings taken from the Augmented Multi-party Interaction meeting corpus. Statistical techniques were employed for this work. Our findings suggest that temporal note-taking overlap information and the semantic content of the written private notes taken by many meeting participants both point to the majority of the most informative meeting events. Thus, the characteristics of note-taking can be seen as a contributing feature for new automatic meeting summarisation approaches and for the development of future meeting browser environments that better support the needs of individuals and organisations.     

Development of a hybrid expert system for nurse shift scheduling

In this article, we discuss the effect of nurse shift job on circadian rhythm, work stress, and some important ergonomics criteria. We also review and compare different nurse shift scheduling methodologies via the criteria of flexibility, consideration of nurse preference, and consideration of ergonomics principles. A hybrid expert system, entitled NURSE-HELP, is developed to facilitate the nurse scheduling process with an emphasis on considering ergonomics criteria. Moreover, the combination of a linear zero-one goal programming and an expert system program reduces the program run time while maintaining the quality of the schedule. The evaluation of the system is done by comparing 18 sets of four-week schedules generated by the head nurses manually and by NURSE-HELP. Concerning the amount of time to generate the schedules, NURSE-HELP averages less than 20 minutes while the head nurses spend about two to four hours. The quality of the schedules is measured by the following four criteria; minimum staff level not satisfied, day off request not granted, backward rotation, and maximum consecutive work periods on the night shift. The results show that NURSE-HELP is superior than the head nurses in preparing schedules, both in terms of time and quality.     

Night shift dose and stress at work

In a new approach to the problem of night work and its consequences, an investigation of the relationships between shift variables, stress at work (environmental and psychosocial aspects), well-being and health, and lifestyle characteristics was carried out, taking into consideration the actual number of remunerated night shifts (‘night shift dose’ (NSD)). Out of the entire workforce (n=173) of a manufacturing plant of the cement industry located in Lower Austria, a group of 31 shiftworkers, working approximately 44 night shifts per year on average was examined in detail. Between night shift dose and psychosocial stress, an important relationship was detected. Taking into account workers' well-being and health, the results suggest that psychosocial and environmental stress factors at work act independently from shift-related stress factors.     

Shell radiance texture functions

The appearance of an inhomogeneous translucent material depends substantially on its volumetric variations and their effects upon subsurface scattering. For efficient rendering that accounts for both surface mesostructures and volumetric variations of such materials, shell texture functions have precomputed irradiance within a volume with respect to incoming illumination, but even with this irradiance data a fair amount of runtime computation is still required. Rather than precompute volume irradiance, we introduce the shell radiance texture function (SRTF), which relates incoming illumination more directly to outgoing surface radiance by representing a set of subsurface transport components from which surface radiance can be calculated without ray marching or runtime evaluation of dipole diffusion. Using this precomputed SRTF information, inhomogeneous objects can be rendered in real time with distant local lighting or global lighting.     

Occupational health services for shift and night workers

It is important for an occupational health service to plan health supervision and measures for shift and night workers considering the biorhythmic and psychosocial desynchronisation, as well as the frequent prevalence of combined effects of adverse environmental and working conditions. The measures taken should be preventive to reduce the expected health risks rather than being rehabilitative. Both a medical surveillance and a counselling service are recommended before and during engagement in shift and night work. Sleep, digestive, metabolic and cardiovascular troubles should be noted and followed up. Medical counselling is especially necessary in the first months of shift and night work exposure and then after long-term exposure. The postulate for timed surveillance and intervention is supported by data of our epidemiologic investigations. The importance of the single health measures is underlined by direct reference to the relevant literature. Recommendations that should be applied in all countries and enterprises are in accordance with the ILO Night Work Convention 1990a and include: (1) appropriate occupational health services provided for night and shift workers, including counselling; (2) first aid facilities during all shift hours; (3) the option of transfer to day work when certified unfit for night work for reasons of health; and (4) measures for women on night shifts, in particular special maternity protection (transfer to day work, social security benefits or an extension of maternity leave). Examples of occupational health services already installed in some states for shift and night workers, and information on future developments are given. Up to now the medical service has been implemented mostly on the basis of collective agreements rather than on the basis of legal provisions. The Austrian Night Shift/Heavy Work Law Regulations of 1981, revised 1993, are cited: workers exposed to night shifts under defined single or combined additional heavy workloads are entitled to a special health assessment, additional rest pauses, additional free time and early retirement depending on years of exposure.