1,720,963 research outputs found
The effect of speed variation on initial and sustaned forces during pushing and pulling activities: a preliminary study
No full textPush and pull activities characterize a significant part of manual material handling tasks in industry. Epidemiological studies show that pushing and pulling activities are associated with shoulder and low back pain. The International Standard 11228-2 describes the approach for risk assessment of push/pull activities, providing the maximum acceptable initial and sus-tained forces for pushing and pulling. The Standard defines maximum acceptable forces, re-quiring not to push/pull faster than a prescribed speed limit (0.1m/s for initial force and 0.3m/s for sustained force). Previous studies and current practice show that workers push carts faster.
The purpose of this study was to evaluate the relationships between speed variation and push forces for pushing tasks in industry. An industrial cart was pushed at different speed val-ues. Maximum initial and sustained push forces were measured. Results showed that increas-ing speed was highly correlated to increasing push forces. The findings have practical value for researchers, occupational physicians and ergonomics practitioners
A thorough investigation on pushing activities in industry: The impact of the variation in the speed of motion and load conditions on initial and sustained forces
Full text linkPushing and pulling wheeled objects represent a significant part of manual material handling activities in industry. Medical investigations and epidemiological studies proved the correlation between such activities and the occurrence of lumbago, low back pain and adverse effects on the shoulders. The ISO 11228–2:2007 provides the recommended limits for pushing and pulling. Such values are the results of psychophysical studies realized under prescribed speed conditions referring to a slow walk. However, observation of real industrial and service sector environments reveals that workers are required to perform pushing activities at higher speed of motion.
The aim of this study was to investigate the impact of the variation in the speed of motion and load conditions on push forces. 96 subjects performed a total of 2592 trials consisting of pushing an industrial trolley for warehouse applications, at different speed values and load conditions. Results confirm the presence of correlation between the increasing speed of motion and push forces. The findings have practical value for researchers, occupational physicians and ergonomics practitioners
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Engineering controls and industrial applications for ergonomics.
No full textRepetitive work including manual material handling of loads at high frequency involves a significant stress of the upper limb, mainly affecting hand and wrist, but even shoulders and low back. Lifting, reaching, and performing repetitive activities with moderate force, cause excessive stress on joints and tendons if performed at high frequency or for a long time. These activities commonly lead to deteriorated postures, awkward body positions and muscular fatigue. Such behaviors are the main cause of occupational diseases as cumulative trauma disorders and work-related musculoskeletal disorders (WMSDs), e.g., tendonitis, low back pain and carpal tunnel syndrome.
WMSDs are considered one of the most common and expensive occupational diseases. Furthermore, work-related WMSDs increase the risk of errors and frequently result in reduced productivity and quality.
Physical and psychosocial factors as the characteristics of tasks and workers, and the work organization are the main risk factors for work-related WMSDs. Other additional factors include the work conditions as noise, illumination, climate and vibration. The health and safety regulations and guidelines require to eliminate the risk or to reduce the exposure by means of engineering and administrative controls. Specifically, engineering controls eliminate or reduce exposure to a physical hazard through the adoption or substitution of engineered machinery and equipment. Administrative controls, or work practice controls, involve changes in the work organization or in work procedures, e.g., training of workers, safety procedures and job schedules.
This chapter presents a brief review on recent innovative engineering controls for the ergonomics of manual workers in several industries (e.g., construction, agriculture, meat-processing, retail and personal service assistance). A procedure for planning the implementation of engineering controls to support the risk elimination or reduction is introduced, together with two practical applications on different industrial workplaces. The ergonomic risk assessment before the introduction of the engineering controls revealed some major risk factor associated with work-related WMSDs. After the adoption of the solutions, the achieved ergonomic improvements led to the reduction of the risk factors. The proposed engineering controls are included in the Solutions Database, a research project for the development of informative documents to support and update the companies about available automated solutions and tools improving ergonomics in occupational environment characterized by manual material handling and repetitive work. The results of this study showed that improving ergonomics and workers’ health and safety is possible even with limited resources
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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