Rapid entire body assessment (REBA)

This technical note details the preliminary stage in the development of a postural analysis tool, Rapid Entire Body Assessment (REBA). REBA has been developed to fill a perceived need for a practitioner's field tool, specifically designed to be sensitive to the type of unpredictable working postures found in health care and other service industries. A team of ergonomists, physiotherapists, occupational therapists and nurses collected and individually coded over 600 postural examples to produce a new tool incorporating dynamic and static postural loading factors, human-load interface (coupling), and a new concept of a gravity-assisted upper limb position. Initial reliability for inter-observer coding shows promise but further work is needed to establish the validity of the tool.     

Good reasons for high variability (low inter-rater reliability) in performance assessment: Toward a fuzzy logic model

Regular performance assessment is an integral part of (high-) risk industries. Past research shows, however, that in many fields, inter-rater reliabilities tend to be moderate to low. This study was designed to investigate the variability of performance assessment in a naturalistic setting in aviation. A modified think-aloud protocol was used as research design to investigate the reasoning pairs of pilots use to assess the performance of an airline captain in a high-risk situation. Standard protocol analysis and interaction analysis methods were employed in the analysis of transcribed verbal protocols. The analyses confirm high variability in performance assessment and reveal the good, albeit fuzzy, justifications that assessor pairs use to ground their assessments. A fuzzy logic model exhibits a good approximation between predicted and actual ratings. Implications for the practice of performance assessment are provided.     

Comparison of ergonomic risk assessment outputs from OWAS and REBA in forestry timber harvesting

Globally, work-related (musculoskeletal disorders (MSDs) are one of the most important health problems encountered by ergonomists. Forest work, especially logging harvesting, is traditionally recognized as one of the most difficult types of physical work and has distinct characteristics. Harvesting works in forestry are composed of the following work stages: logging, skidding, and loading. This study aimed to examine risk factors of MSDs associated with different work postures during harvesting under variable external conditions by comparing work stages using the Ovako Working posture Assessment System (OWAS) and Rapid Entire Body Assessment (REBA). A statistically significant difference was observed between the two methods. While the difference in risk to the musculoskeletal system was statistically significant in different work stages using REBA, logging and skidding were assigned to the same risk level using OWAS. Easy-to-use ergonomic hand tools should be developed that are suitable for working conditions and help reduce MSD risk in forestry workers.     

Investigative study and sensitivity analysis of Rapid Entire Body Assessment (REBA)

The paper aims primarily to study the sensitivity of Rapid entire body assessment (REBA) and identification of insensitive and sensitive posture zones. The investigative study, and sensitivity analysis of REBA offer deeper insights into the methodology used for the assessment of posture. Full factorial design is divided into parts using a forward approach to access the sensitivity. One parameter is varied keeping other parameters constant to understand its effect on the output score. Combinations of posture where no change was observed were identified. Posture scores were also noted involving sudden jumps. Regression analysis was performed to identify relative importance or weightage of the body and other variables in estimating the final REBA score. The justification of the REBA methodology available in the existing literature is very limited. This paper also demonstrates the need for understanding of REBA method among the researchers. With this paper, ergonomic practitioners can be made aware of insensitive and sensitive zones in posture assessment.OriginalityThis is the first paper that primarily aims to establish the sensitivity of REBA and identifying insensitive postures or problems in REBA assessment. Few research gaps are identified.     

Generic methodology for the probabilistic reliability assessment of some structural properties: a graph theoretical approach

The graphical characterisation of many important structural properties, such as controllability, observability, diagnosability of many kinds of structured systems, uses mainly four types of elementary graphical conditions: connectivity, complete matching, linking and distance conditions. Since structural properties depend on different associations of elementary conditions, it is interesting to study elementary conditions. This paper is the first part of this global approach based on elementary graphical conditions and we choose to study the so-called connectivity and complete matching conditions. Starting from the graphical representation associated with a system, the paper provides Boolean expressions of the connectivity and complete matching conditions based on the edges validity, which can be linked to the physical components operating state. These expressions can then be used to define and compute the reliability of a structural property knowing the reliability of the system physical components. This knowledge can be important during both conception and exploitation stages. The proposed methods are quite intuitive and simple to implement and have basically polynomial complexity orders. This makes our approach well suited to analyse large-scale systems.     

BASE: an assistant tool to precisely simulate energy consumption and reliability of energy‐efficient storage systems

The concept of green storage in cluster computing has recently attracted enormous interest among researchers. Consequently, several energy‐efficient solutions, such as multi‐speed disks and disk spin down methods, have been proposed to conserve power in storage systems and improve disk access. Some researchers have assessed their proposed solutions via simulations, while others have used real‐world experiments. Both methods have advantages and disadvantages. Simulations can more swiftly assess the benefits of energy‐efficient solutions, but various measurement errors can arise from procedural shortcomings. For instance, many power simulation tools fail to consider how heat increases the power overhead of disk operations. Some researchers claim that their modeling methods reduce the measurement error to 5% in the single disk model. However, the demand for large‐scale storage systems is growing rapidly. Traditional power measurement using a single disk model is unsuited to such systems because of their complex storage architecture and the unpredictability of numerous disks. Consequently, a number of studies have conducted real machine experiments to assess the performance of their solutions in terms of power conservation, but such experiments are time consuming. To address this problem, this study proposes an efficient simulation tool called Benchmark Analysis Software for Energy‐efficient Solution (BASE), which can accurately estimate disks' power consumption in large‐scale storage systems. We evaluate the performance of BASE on real‐world traces of Academia Sinica (Taiwan) and Florida International University. BASE incorporates an analytical method for assessing the reliability of energy‐efficient solutions. The analytical results demonstrate that the measurement error of BASE is 2.5% lower than that achieved in real‐world experiments involving energy‐estimation experiments. Moreover, the results of simulations to assess solution reliability are identical to those obtained through real‐world experiments. Copyright © 2015 Copyright © 2015 John Wiley & Sons, Ltd.     

Multi-affect(ed): improving recommendation with similarity-enhanced user reliability and influence propagation

Traditional recommendation algorithms predict the latent interest of an active user by collecting rating information from other similar users or items. Recently, more and more recommendation systems attempt to involve social relations to improve recommendation performance. However, the existing works either leave out the user reliability or cannot capture the correlation between two users who are similar but not socially connected. Besides, they also take the trust value between users either 0 or 1, thus degenerating the prediction accuracy. In this paper, we propose an efficient social affect model, multiaffect(ed), for recommendation via incorporating both users’ reliability and influence propagation. Specifically, the model contains two main components, i.e., computation of user reliability and influence propagation, designing of user-shared feature space. Firstly, a reliability calculation strategy based on user similarity is developed for measuring the recommendation accuracy between users. Then, the factor of influence propagation relationship among users is taken into consideration. Finally, the multi-affect(ed) model is developed with user-shared feature space to generate the predicted ratings.     

MatCarloRe: An integrated FT and Monte Carlo Simulink tool for the reliability assessment of dynamic fault tree

With the aim of a more effective representation of reliability assessment for real industry, in the last years concepts like dynamic fault trees (DFT) have gained the interest of many researchers and engineers (dealing with problems concerning safety management, design and development of new products, decision analysis and project management, maintenance of industrial plant, etc.). With the increased computational power of modern calculators is possible to achieve results with low modeling efforts and calculating time. Supported by the strong mathematical basis of state space models, the DFT technique has increased its popularity. Nevertheless, DFT analysis of real application has been more likely based on a specific case to case resolution procedure that often requires a great effort in terms of modeling by the human operator. Moreover, limitations like the state space explosion for increasing number of components, the constrain of using exponential distribution for all kind of basic events constituting any analyzed system and the ineffectiveness of modularization for DFT which exhibit dynamic gates at top levels without incurring in calculation and methodological errors are faces of these methodologies. In this paper we present a high level modeling framework that exceeds all these limitations, based on Monte Carlo simulation. It makes use of traditional DFT systemic modeling procedure and by replicating the true casual nature of the system can produce relevant results with low effort in term of modeling and computational time. A Simulink library that integrates Monte Carlo and FT methodologies for the calculation of DFT reliability has been developed, revealing new insights about the meaning of spare gates.     

A new scoring system for the Rapid Entire Body Assessment (REBA) based on fuzzy sets and Bayesian networks

Traditional methods for assessing the risk of work-related musculoskeletal disorders (WMSDs) have a low sensitivity to changes in input variables. Using them, it is possible to obtain the same risk score for totally different postures, and in some cases, the effectiveness of ergonomic interventions cannot be demonstrated. This study aimed to develop a new scoring system for REBA, FBnREBA, using fuzzy sets and the Bayesian network (BN) approach to cover the drawbacks of the traditional REBA. First, the risk factors of WMSDs were defined in terms of fuzzy membership sets. Next, a BN model was developed based on REBA. Fourteen different postures were assessed using FBnREBA, and the results were compared with those of the original REBA. Lastly, a case study was performed to demonstrate how the new scoring system can be used to rank various interventions based on their effectiveness. FBnREBA is a BN model with 26 nodes and is based completely on REBA, but its results differ from those of REBA for identical postures. A comparison of the results of FBnREBA with those of REBA indicated that FBnREBA is more sensitive to changes in WMSDs risk factors than REBA. A case study was conducted using FBnREBA, and the effectiveness of modifying each body segment was determined and ranked. FBnREBA is more sensitive to changes in input variables so that it is unlikely to obtain the same risk score for different body postures. The introduced methodology can be used to modify the scoring systems of other similar methods.     

On the reliability of the occlusion technique as a tool for the assessment of the HMI of in-vehicle information and communication systems

In recent years considerable efforts have been spent on the development of the occlusion technique as a procedure for the assessment of the human-machine interface of in-vehicle information and communication systems (IVIS) designed to be used by the driver while driving. The importance and significance of the findings resulting from the application of this procedure depends essentially on its reliability. Because there is a lack of evidence as to whether this basic criterion of measurement is met with this procedure, and because questionable reliability can lead to doubts about their validity, our project strove to clarify this issue. This paper reports on a statistical reanalysis of data obtained from previous experiments. To summarise, the characteristic values found for internal consistency were almost all in the range of .90 for the occlusion technique, which can be considered satisfactory.     

Human factors assessment of conflict resolution aid reliability and time pressure in future air traffic control

Though it has been reported that air traffic controllers' (ATCos') performance improves with the aid of a conflict resolution aid (CRA), the effects of imperfect automation on CRA are so far unknown. The main objective of this study was to examine the effects of imperfect automation on conflict resolution. Twelve students with ATC knowledge were instructed to complete ATC tasks in four CRA conditions including reliable, unreliable and high time pressure, unreliable and low time pressure, and manual conditions. Participants were able to resolve the designated conflicts more accurately and faster in the reliable versus unreliable CRA conditions. When comparing the unreliable CRA and manual conditions, unreliable CRA led to better conflict resolution performance and higher situation awareness. Surprisingly, high time pressure triggered better conflict resolution performance as compared to the low time pressure condition. The findings from the present study highlight the importance of CRA in future ATC operations.

Practitioner Summary: Conflict resolution aid (CRA) is a proposed automation decision aid in air traffic control (ATC). It was found in the present study that CRA was able to promote air traffic controllers' performance even when it was not perfectly reliable. These findings highlight the importance of CRA in future ATC operations.     

Comparison of OWAS,RULA and REBA for assessing potential work-related musculoskeletal disorders

This study compared three representative observational methods for assessing musculoskeletal loadings: Ovako Working Posture Analysis System (OWAS), Rapid Upper Limb Assessment (RULA), and Rapid Entire Body Assessment (REBA). The comparison was based on 209 cases of upper-body musculoskeletal disorders (MSDs) diagnosed by medical doctors. The most awkward/stressful posture in each participant's tasks was assessed using these techniques. Postural loadings were rated more highly by the RULA than by the OWAS and REBA (p < 0.01). The chi-square test and logistic regression analysis showed that only RULA grand score and action level, and REBA action level were associated with MSD work-relatedness (p < 0.01, p < 0.05, and p < 0.05, respectively). The percentage concordant values of the logistic model for the RULA grand score and action level were 52.4% and 44.8%, respectively, while the percentage concordant value for the REBA action level was 22.1%. Therefore, the RULA may be the best system for estimating the postural loads and work-relatedness of MSDs.Relevance to industryWork-related musculoskeletal disorders are the leading cause of workplace disability in the developed countries. For preventing the disorders, quantification of musculoskeletal loads is required.     

An Evaluation of the Reliability of Complex Systems Using Shadowed Sets and Fuzzy Lifetime Data

In this paper, we consider the problem of the evaluation of system reliability using statistical data obtained from reliability tests of its elements, in which the lifetimes of elements are described using an exponential distribution. We assume that this lifetime data may be reported imprecisely and that this lack of precision may be described using fuzzy sets. As the direct application of the fuzzy sets methodology leads in this case to very complicated and time consuming calculations, we propose simple approximations of fuzzy numbers using shadowed sets introduced by Pedrycz (1998). The proposed methodology may be simply extended to the case of general lifetime probability distributions.     

Validity and reliability of the IAT: Measuring gender and ethnic stereotypes

The Implicit Association Test (IAT) was developed in response to reports of low validity of explicit (self-report) measures of attitudes, stereotypes, and prejudices. Usually, people are unwilling to report what they think and feel about other races, groups, and nationalities. The IAT has been written about in many books, newspapers, journal articles, websites, and has been featured frequently on radio and television many times; its web site has now reached a peak of 5 million visits. However, despite this popularity its validity and particularly its reliability is under question. This article reports on the validity and reliability of the IAT. Four different experiments were conducted on 150 students at California State University, Long Beach to investigate the temporal reliability of IAT. Also students’ opinion (trust) about the validity and reliability of the test was evaluated. The results showed that while there are numerous reports of moderate validity of the test, its reliability as measured in this study, particularly for the first time users, is relatively low. Familiarity with similar tests, however, improves its reliability.     

eMMC可靠性分析与增强对策研究

eMMC是可以自我管理的闪存（NAND flash）芯片,内部集成了控制器,实现了多芯片封装,简化了应用接口设计,节省了板级空间,在移动终端领域得到了广泛应用。然而,基于flash的存储器件在掉电时容易出现比特位损坏、元数据损坏、非串行写、甚至器件不可用等可靠性问题。针对如何提高eMMC的可靠性进行了研究,提出了一些可靠性增强措施。首先,全面梳理了eMMC规范提供的可靠性特性,包括分区管理、写保护管理、可靠写、数据标签、断电通知等。继而对现有的各种可靠性措施进行了综合分析,并提出了一些提升可靠性的措施,包括,文件系统感知的磨损均衡、根据数据属性映射到合理分区、减少写入次数降低写放大效应,面向手机应用的元数据去冗、应用差异化细粒度控制可靠性、确保一致性的前提下减少日志等。     

The validation of the E-Victimisation Scale (E-VS) and the E-Bullying Scale (E-BS) for adolescents

This study investigates the psychometric properties of the E-Victimisation Scale (E-VS) and E-Bullying Scale (E-BS) designed to assess Cyber Bullying among Chinese adolescents. Participants were 484 adolescents aged between 11–16 years randomly recruited from high schools within a region. Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) were applied to investigate the factorial structure of these scales. Reliability was examined by Cronbach’s alpha coefficients by sex. The convergent validity was investigated by correlations among these scales and the Centre for Epidemiological Studies-Depression for Children as well as the Zung’s Anxiety Scales. A single-factor model for the E-VS and a 2-factor model for the E-BS were resulted from the EFA with large factor loadings and about 47% and 56% of variance explained respectively. Cronhach’s alpha values provided evidence for good internal reliability with values ranging from 0.55 to 0.96. Correlations between the E-VS and Depression as well as Anxiety scales showed positive and significant relationships, however, the E-BS was only related to Depression. Psychometric evidence has shown that both E-VS and E-BS are valid instruments for measuring Cyber bullying behaviour and victimisation. Further studies are required on the test–retest reliability, discriminate validity, responsiveness, as well as normative information for standardisation.     

Validation of the Cybervictimization Questionnaire (CYVIC) for adolescents

The Cybervictimization Questionnaire (CYVIC) for adolescents was designed to assess the extent to which the informant is a victim of aggression by mobile phone or Internet. The goal of this study is to analyze its factor and criterion validity and reliability in a sample of adolescents of Asturias (Spain). For this purpose, the CYVIC was applied to 3159 young people, aged 12 to 18, along with three scales to measure Internet Risk Behaviors, Offline School Victimization, and Self-esteem. Regarding factor validity, the model that best represents the internal structure of the CYVIC has four factors (Impersonation, Visual-Sexual Cybervictimization, Written-Verbal Cybervictimization, and Online Exclusion) and four additional indicators of Visual Cybervictimization-Teasing/Happy slapping. Regarding criterion validity, the CYVIC scores correlate positively with Internet Risk Behaviors and Offline School Victimization, and negatively with Self-esteem, three variables that previous empirical evidence indicates correlate with cybervictimization. The reliability of the CYVIC factors and items are both adequate. Therefore, it is concluded that the CYVIC is a valid and reliable self-report measure of cybervictimization in adolescents.     

A method for exact reliability of consecutive2-out-of-(r, r)-from-(n, n):F systems

A new reliability model, consecutive 2‐out‐of‐(r, r)‐from‐(n, n):F model, is proposed. The consecutive 2‐out‐of‐(r, r)‐from‐(n, n):F system consists of a square grid of side n (containing n² components) such that the system fails if and only if there is at least one square of side r which includes among them at least two failed components. For i.i.d. case an algorithm is given for computing the reliability of the system. The reliability function can be expressed by the number of 0–1 matrices having no two or more 0s at any square of side r.     

Techniques of subjective workload assessment: a comparison of SWAT and the NASA-Bipolar methods

Abstract

Assessment of subjective workload is becoming increasingly important in the evaluation of human-machine systems. Two popular methods were compared: (1) the Subjective Workload Assessment Technique (SWAT) that employed a conjoint measurement procedure to confer interval scale properties on the workload ratings, and (2) a technique under development at NASA that used an individually weighted workload score. Both methods were applied in a laboratory experiment that required the rating of a number of single- and dual-tracking and spatial transformation tasks. Both subjective assessment techniques displayed similar sensitivity to the different task manipulations. However, both techniques failed to detect the resource competition effects in the dual-task performance, and were in general insensitive to response execution processing demands. A notable difference between the two techniques was that the NASA-Bipolar ratings consistently had a smaller between-subject variability than the SWAT ratings. Discussion of the results is centred around the issue of the validity of assessment of subjective workload in general, and the construct and concurrent validity of the two techniques in particular.