Resource scheduling approach for multimedia cloud content management

With the development of multimedia application and services, the multimedia technology has already permeated each aspect of our life. Multimedia cloud is used for processing multimedia services. However due to huge data volume, high concurrency, strict real-time, resource scheduling for content dissemination in multimedia cloud still remain challenges. In order to increase the user satisfaction and decrease completion time of content dissemination, the resource scheduling for content dissemination in multimedia cloud is proposed in this paper. The multimedia jobs are clustered according to user expectation and job complexity. The job with highest priority will be executed first. Moreover, considered multimedia task types and the impact of stragglers, the multimedia task scheduling based on task types and node workload is presented, which is a time-efficient scheduling approach. The experiments are conducted and the experiment results show that the job clustering algorithm-based user expectation and job complexity in multimedia cloud has better user satisfaction and shorter completion time, while the multimedia task scheduling based on task types and node workload can reduce completion time and achieve load-balancing.     

Integration of task networks and cognitive user models using coloured Petri nets and its application to job design for safety and productivity

Changes of task demands due to unforeseen events and technological changes can cause variations in job design such as modifications to job procedures and task allocation. Failure to adapt to job design variations can lead to human errors that may have severe consequences for system safety. Existing techniques for task modelling cannot adequately model how task networks can be adapted to changing work conditions and task demands. Therefore, there is a need to integrate task networks with cognitive user models that indicate how operators process information, make decisions, or cope with suspended tasks and errors. The work described here presents a tool for integrating task and cognitive models using coloured Petri nets. The cognitive user model comprises two modules of attention management (selective and divided attention), a module of memory management of suspended tasks and a module of work organization. Performance Shaping Factors (e.g., workload, fatigue and mental-tracking load) are calculated at any point in time to take into account the context of work (e.g., competing activities, errors and suspended tasks). Different types of human error can be modelled for rule-based behaviours required in proceduralized work environments. Simulation analysis and formal analysis techniques can be applied to process control tasks to verify job procedures, workload management strategies and task allocation schemes in response to technological changes and unfamiliar events.     

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Abstract

In a real work situation the operative strategy choosen by subjects depends on three variables, the characteristics of the operator (training, motivation, age, health, etc.); the characteristics of the task, i.e. the level of task requirements; and the level of workload, which itself results from the operative strategy. Ergonomista try often to measure the workload, but do not pay enough attention to the regulating effects exerted by the workload, through feed-back, on the strategy used by operators. This paper summarizes an experimental study carried out in a ATCC, showing how air traffic controllers modify their operative methods when workload increases.     

Resource Allocation for Reliable Communication Between Controllers and Switches in SDN

In software-defined networking (SDN), the communication between controllers and switches is very important, for switch can only work by relying on flow tables received from its controller. Therefore, how to ensure the reliability of the communication between controllers and switches is a key problem in SDN. In this paper, we study this problem from two aspects: the controller placement and the resource backup aspect. Firstly, in order to implement the reliable communication and meet the required propagation delay between controllers and switches, a min-cover based controller placement approach is proposed. Then, in order to protect both controllers and control paths from regional failure, a backup method based on an exponential decay failure model is proposed, which considers the regional influence and the survivability of backup controllers and control paths. Simulations show that our controller placement approach can meet the reliability and delay requirement with appropriate controller allocation scheme, and our backup method can improve the survivability of backup controllers and control paths while ensuring the performance of control network.     

Whither workload?

Although the demands placed on flight deck personnel are not continuously excessive, the short periods of high load combine to produce a cumulative effect at the end of an operation. At the RAF Institute of Aviation Medicine, aircrew are examined on their in-flight workload by a questionnaire method and this is compared with other methods including physiological measurement. The effects of work away from the flight deck, and of factors peripheral to the job situation, are considered, and it is suggested that care must be taken to avoid eliminating job satisfaction with reduction in workload.     

Doing a Good Job—the Effect of Primary Task Quality on Well‐Being and Job Satisfaction

This paper investigates whether employees’ assessment of their primary task quality has a significant impact on their well‐being and job satisfaction, respectively. Furthermore, the paper hypothesizes that professional values and norms affect employees’ quality expectations on their work tasks and thus their assessment of primary task quality. The paper proposes a measure for primary task quality and uses it in the analyses of responses from 1,247 preschool teachers and teaching assistants in 94 public daycare centers in Denmark. The results indicate that an important factor for employees is their experience of quality in the job they perform. Moreover, quality expectations can differ between employees performing the same task due to, for example, difference in professional training. This leads us to propose a new research direction for job design theory that addresses employees’ assessment of the quality of their primary task job performance.     

Human performance assessment of a single air traffic controller conducting multiple remote tower operations

The innovative concept of multiple remote tower operations (MRTO) can maximize cost savings by applying video panorama‐based remote tower working positions, which can facilitate fewer air traffic controllers (ATCO) to provide the air traffic services (ATS) function for more airports. Five subject‐matter experts, qualified remote tower ATCOs, participated in this research work by applying the human error template (HET) and comparing workload between physical tower operations and MRTO using NASA‐TLX (Task Load Index). The results demonstrate that augmented visualization provided sufficient technical support for a single ATCO to perform tasks originally designed to be performed by four ATCOs, however, the demands of the associated multiple tasks induced significant workload. There were significant differences in ATCOs’ mental demand, temporal demand, effort, and frustration between MRTO and physical tower operations. This innovative technology may induce human–computer interaction (HCI) issues that impact ATCO's perceived workload. This creates a need for further research on how to manage ATCO's workload in a multiple remote tower environment. This research work provided scientific evidence that MRTO can achieve the objectives of Single European Sky Air Traffic Management Research program. The findings can be applied to both ATCO training design and remote tower system design.     

Web集群服务器中分发静态请求的调度算法*

为分发静态请求提出一种自适应的基于文档大小的调度算法ADSB,它使用资源占用时间来衡量负载,并根据被请求文档的大小来分发请求,均衡各个后台服务器的负载;ADSB根据负载历史周期地预测即将到来的负载统计特性,并根据预测结果来调整算法的参数;由于有着目标位置特性,ADSB能获得很高的缓存命中率;因为实际静态文档的大小服从重尾分布,所以分发大小不同的文档到不同的服务器,使ADSB减小了小文档的平均响应时间,同时大文档也没受到明显的影响。实验表明,ADSB的性能优于已有的经典的调度算法。     

Modeling and predicting mental workload in en route air traffic control: critical review and broader implications

OBJECTIVE: We perform a critical review of research on mental workload in en route air traffic control (ATC). We present a model of operator strategic behavior and workload management through which workload can be predicted within ATC and other complex work systems. BACKGROUND: Air traffic volume is increasing worldwide. If air traffic management organizations are to meet future demand safely, better models of controller workload are needed. METHOD: We present the theoretical model and then review investigations of how effectively traffic factors, airspace factors, and operational constraints predict controller workload. RESULTS: Although task demand has a strong relationship with workload, evidence suggests that the relationship depends on the capacity of the controllers to select priorities, manage their cognitive resources, and regulate their own performance. We review research on strategies employed by controllers to minimize the control activity and information-processing requirements of control tasks. CONCLUSION: Controller workload will not be effectively modeled until controllers' strategies for regulating the cognitive impact of task demand have been modeled. APPLICATION: Actual and potential applications of our conclusions include a reorientation of workload modeling in complex work systems to capture the dynamic and adaptive nature of the operator's work. Models based around workload regulation may be more useful in helping management organizations adapt to future control regimens in complex work systems.     

Establishment of overall workload assessment technique for various tasks and workplaces

A model for assessing workloads called overall workload level (OWL) was developed by introducing linguistic variable sets and applying the analytic hierarchy process (AHP) to estimate the external workload imposed on a human operator in man–machine systems. To do this, a five-point linguistic variable set scale was constructed and their hierarchical prioritization procedures were set up. The task and workplace variables (e.g., physical, environmental, postural, and mental job demand workloads) which can obtain the operator's perception of workload are selected as workload factors and the AHP technique is used to collect different weights. Finally, OWL is calculated using a computer-assisted system to determine the level of overall workload impinged on an operator. The OWL was implemented in an actual industrial environment from a physiological and epidemiological viewpoint to determine the validity of the model. Furthermore, the results obtained by applying OWL were compared to the results obtained by applying the overall workload (OW) of the NASA task load index (TLX). The results show that there is a close linear relationship among the physiological measurements, the severity of injury and illness rates, OW, and OWL. Thus, this approach can be used for problem identification and for solving widespread occupational workloads.

Relevance to industry

The determination of workloads imposed on a human operator plays an important role in designing and evaluating an existing man–machine system. Therefore, a model for assessing workloads was developed to estimate the external workload imposed on a human operator in man–machine systems. This model can be used for problem identification and for solving widespread occupational workload.     

A novel method to monitoring changes in cognitive load in video‐based learning

One of the golden rules in instructional design methods is to optimize the use of working memory capacity and avoid cognitive overload. The study of cognitive load has historically relied on one's introspection. However, it is difficult to capture changes in cognitive load levels during learning sensitively. This paper suggests an approach to investigating dynamic changes in cognitive load by using a pupillometry. With the method, this study explores the effects of learners' prior knowledge and task complexity on cognitive load. An experiment was conducted on two groups of students (N = 19) with distinct levels of prior knowledge. In the experimental session, participants watched a video lecture on a mathematics proposition, while being eye‐tracked. The lecture consists of sections, which can be either a high task complexity or a low task complexity based on elements they have. Pupil dilations acquired in each section were used to explore the time course of cognitive load. To formulate cognitive load patterns, a time‐series clustering was used. The research conducted a chi‐square analysis to test differences in cognitive load patterns by prior knowledge and task complexity. Results show that pupil dilation patterns can be applied to monitor changes in cognitive load during learning.     

Job performance through mobile enterprise systems: The role of organizational agility,location independence,and task characteristics

This study examines how organizational workers improve their perceived job performance through the use of Mobile Enterprise Systems (MES), while also investigating the impact of perceived organizational agility and location independence on technology acceptance of MES. This study also tests the moderating role of task characteristics (task significance and feedback) on the relationship between MES usage and perceived job performance. Based on the extant technology acceptance model (TAM), we proposed an extended TAM and conducted a large-scale survey among organizational workers who use MES in their workplace across industries. Our findings suggest that both positive attitude toward MES and a high level of habitual MES usage are positively associated with perceived job performance, and that task characteristics positively moderate the relationship between habitual usage (attitude toward MES) and perceived job performance. More importantly, we also found that organizational agility is positively associated with both perceived ease of use and perceived usefulness, while location independence is positively associated with perceived ease of use. The present findings provide us with a deeper understanding of how organizational workers utilize MES and how they improve their perceived job performance through the use of MES. Based on these findings, we discuss further implications and limitations.     

Mediating Effect between Supportive Culture and Job Satisfaction in Administrative Services at Higher Education Institutions

The purpose of this article is to examine halo effect and organizational commitment in relation to employees' job satisfaction and organizational supportive culture at universities in Taiwan. The study used a questionnaire to collect data from 210 female faculty members of Taiwanese universities. The conceptual model was tested mediating the effect of structural equation modeling with maximum likelihood estimation. This study not only found the mediating role of halo effect and organizational commitment between supportive culture and job satisfaction, but also proved that a supportive culture in universities is directly and positively related to job satisfaction and that emotional and identification‐oriented organizational commitment may affect job satisfaction in a positive way among female faculty members. © 2012 Wiley Periodicals, Inc.     

The Regulation of Working Methods as a Function of Work-load among Air Traffic Controllers

Abstract

A series of field studies among air traffic controllers is reviewed. It largely concentrated on regulatory aspects of operational behaviour, using a model based on the concept of ‘ economy ’ in the individual's selection of operating procedures.

Attention is directed at processes involving reasoning, the receipt and transmission of information, and the division of tasks between controllers at the same station. The basic hypothesis, which is supported by numerous data, is that for a given task and a given controller certain operating procedures are less costly than others; that is, they generate lower levels of load. These procedures will therefore be more and more employed as work demand increases, together with the relaxation of certain, self-imposed, qualitative criteria.

This regulatory feedback between work-load and operating methods is used by the controller to avoid the abrupt onset of overload conditions and to delay satiation. For the investigator, these progressive changes in operating procedure can provide indirect indices of load. Several ergonomic consequences of this approach for system design are discussed.     

Assessing mental workload in virtual reality based EOT crane operations: A multi-measure approach

BackgroundEye-movement metrics and subjective workload measures are extensively used to determine mental workload of participants. The aim of this study was to assess Electric overhead travelling (EOT) crane operators’ mental workload variability based on eye movement metrics such as fixation frequency, fixation duration, saccade duration, saccade amplitude, and fixation/saccade ratio during EOT crane operations in virtual reality (VR) based EOT crane simulator.MethodsA 2^k (k = 3) factorial experiment with factors namely, hazardous scenario, activity level, and trial was designed and conducted to demonstrate the proposed assessment approach. Throughout the experiment, we recorded the eye movements of 12 EOT crane operators of a steel industry of authors’ country. Post experiment, the National Aeronautics and Space Administration task load index (NASA-TLX) was adopted as a subjective workload measure and run time of task completion was recorded. Eye-movement metrics, subjective workload measure, run time were tested with multivariate analysis of variance (MANOVA), and three way repeated measure analysis of variance (ANOVA).ResultsAt the level of α = 0.05, the experimental factors significantly influence the means of eye movement metrics, subjective ratings and run time. There was also significant influence among their interactions. A positive correlation was also found for eye movements metrics with NASA-TLX and run time.ConclusionsEye movement metrics help in understanding the mental workload of participants unobtrusively and continuously. Analysis of subjective workload measure and run time along with eye-gaze analysis provide a deeper understanding on the pattern of mental workload.     

A psychophysiological investigation of system efficiency in public telephone switchrooms

Subjective mood and performance efficiency among operators of public telephone switchboards were studied as a function of interface design and operating procedures. A within-subjects field study was carried out to compare system efficiency within two different types of switchroom; one employing earlier-designed ‘cord’ switchboards, the other employing ‘cordless’ technology in a more ergonomically-designed switchroom. Fifteen subjects were studied, using a minimal intervention technique as they performed their normal operating task, to provide data throughout one working day in either system. EEG and ECG measures were obtained continuously in addition to a variety of sampled performance data and mood ratings.

On the cord design of switchboard, operators were found: (i) to carry a consistently heavier workload of concurrent calls; (ii) to be dramatically more responsive to diurnal fluctuations in call-traffic level, while maintaining more stable ‘caller waiting times’ and ‘effective call connections’; (iii) to display these advantages without exhibiting higher levels of physiological stress and (iv) to report consistently higher levels of psychological well-being.

From these findings and the results of two earlier studies it is concluded that the cord operators' greater efficiency, and professed higher levels of job satisfaction, derive mainly from the advantages which their more comprehensible and flexible system provides them in attaining and maintaining a high-quality service.     

How agile software development methods reduce work exhaustion: Insights on role perceptions and organizational skills

Agile methods are widely used in the software industry as a way to more rapidly develop and deliver new software. They define iterative work processes, advocate self‐organization and openness for change, and prescribe how software developers interact with each other and external stakeholders. Despite their popularity, it is unclear how agile methods influence work exhaustion in software developers and how developer skills play into this effect. On the one hand, agile methods may reduce software developers' work exhaustion by levelling out their workload across the entire duration of a project. On the other hand, agile methods exert a high level of pressure on software developers to continuously deliver working software, create many intensive social interactions, and to frequently adapt to changes. In light of these effects, prior research could not explain why some software developers become less exhausted from using agile methods, whereas others perceive the exact opposite. Based on the job demand‐control model, we develop a theoretical model connecting agile method use to individual developer skills and to two established determinants of employee exhaustion: role conflict and role ambiguity. We tested our research model in a field study among 1894 software developers in 217 project teams that used agile methods. The random coefficient modelling results show that agile method use facilitates the achievement of clear and unambiguous role perceptions and thereby reduces work exhaustion in developers, particularly if developers possess the organizational skills to effectively interact with others in their organization. We highlight implications for theory on the individual‐level effects of software development methods and provide practical insights for software companies.     

Variations in ATC-Work Load as a Function of Variations in Cockpit Workload

Abstract

The relation between pilots‘ workload and radar controllers‘ workload was investigated. Pilots‘ workload served as the independent variable. It was assumed that a number of levels of workload can be distinguished in a standard airport, traffic circuit under visual flight rules. The dependent variable (controllers’ workload) was measured by response frequency on an auditory binary choice task. Results indicate a rise in radar controllers’ workload in a predicted direction for a number of pilots’ workload levels.     

面向高性能计算环境的作业优化调度模型的设计与实现

高性能计算环境聚合了多个分布在不同地域、不同组织机构的高性能计算资源,面向用户提供统一的访问入口和使用方式,由系统中间件根据用户作业请求匹配合适的高性能计算资源。随着环境应用编程接口的开放以及作业请求数量的大幅增加,面对高并发作业提交请求时,目前采用的即时调度模型会由于网络等原因导致一定数量的请求处理失败,同时缺乏灵活性。针对此问题,优化了环境作业调度模型,引入作业环境队列,细化了作业系统层状态,增加了作业调度策略可配置性,并基于环境中间件SCE实现了系统原型。经测试,在单核心服务每分钟处理近200个作业提交请求的工作负载下,无因系统和网络原因引起的作业提交出错现象;在共计1 000个作业中,近500个作业提交命令请求在0.3s以内完成,800余个作业提交命令请求在0.5s以内完成。