Sequencing labor-intensive production by ergonomic assessment for reduction of work-related musculoskeletal disorders

For labor-intensive environments, feasibility of the production schedule is determined in part by the physical human capacity to complete jobs assigned in the sequence. While the physical effect of the production schedule might be perceptible, it is likely not a decision factor when allocating jobs to the sequence. In the most basic sense, this is an inefficient use of finite human capacity but more severely, the physical factors associated with job processing requirements may be contributing to the development of a work-related musculoskeletal disorder. Identification of musculoskeletal risks is well demonstrated by ergonomic assessment but the challenge of intervention and absent in existing methods is cohesion between the demands of production and preservation of humans in the relative short-term. This thesis will therefore define novel job dispatching rules considerate of cumulative effects and musculoskeletal risk for job processing requirements based on the Rapid Entire Body Assessment (REBA). In this way, the sequence of jobs may function as an ergonomic administrative control that exposes the human processor to the minimal necessary physical burden or risk associated with the production schedule

Report of the panel on geopotential fields: Magnetic field, section 9

The objective of the NASA Geodynamics program for magnetic field measurements is to study the physical state, processes and evolution of the Earth and its environment via interpretation of measurements of the near Earth magnetic field in conjunction with other geophysical data. The fields measured derive from sources in the core, the lithosphere, the ionosphere, and the magnetosphere. Panel recommendations include initiation of multi-decade long continuous scalar and vector measurements of the Earth's magnetic field by launching a five year satellite mission to measure the field to about 1 nT accuracy, improvement of our resolution of the lithographic component of the field by developing a low altitude satellite mission, and support of theoretical studies and continuing analysis of data to better understand the source physics and improve the modeling capabilities for different source regions

The fund-flow approach. A critical survey

The fund-flow approach to production theory was first proposed by Nicholas Georgescu-Roegen almost half a century ago. Since then, from time to time it has received attention, but, probably because of its analytical complexity and difficulty to deliver sound "operational conclusions", it is now almost abandoned. The approach has been also recently criticized for its instrumental assumption of constant efficiency of funds, by emphasizing its limitations in addressing issues related to fixed capital depreciation. The paper critically surveys Georgescu-Roegen's original model, together with the later developments and modifications. It also discusses the recent criticisms. The conclusion is that, despite its drawbacks, the fund-flow approach has a "competitive advantage" in the actual description of production as a process unfolding in time and entailing a temporal coordination between different elements. In this respect, it seems that most of its fruitful applications have yet to come.Fund-flow model; Georgescu-Roegen; Production theory;Returns to scale; Technical coefficients

Liberating clocks: Developing a critical horology to rethink the potential of clock time

Across a wide range of cultural forms, including philosophy, cultural theory, literature and art, the figure of the clock has drawn suspicion, censure and outright hostility. In contrast, even while maps have been shown to be complicit with forms of domination, they are also widely recognised as tools that can be critically reworked in the service of more liberatory ends. This paper seeks to counteract the tendency to see clocks in this way, arguing that they have many more interesting possibilities than they are usually given credit for. An analysis of approaches to clocks in continental philosophy critiques the way they have too often been dismissed as unworthy of further analysis, and argues that this dismissal is based upon an inadequate understanding of how clocks operate. Seeking to move towards more critical and curious approaches, the paper draws inspiration from critical cartography in order to call for the development of a ‘critical horology’ which would emphasise both the fundamentally political nature of clocks, and the potential for designing them otherwise. A discussion of temporal design provides a range of examples of how clocks might open up new horizons within the politics of time

Development of a job rotation model for a noise hazard reduction

Job rotation is a significant approach of job design used in manufacturing, assembly or any service providing system, which requires the workers to move between different tasks, at fixed or irregular periods of time. Nowadays, an effective job rotation is increasingly employed in organizations because it helps to reduce and balance the hazard exposure among the workers. An effective job rotation requires optimum rotation parameter setting to ensure the final results will give benefits, for both occupational safety and health, and operational cost. Most of the job rotation studies by previous researchers have been performed for heavy engineering industry such as automotive assembly, forestry and construction site, but a lack of study is observed for the food and beverage manufacturing industries. In this thesis, a job rotation model of a food and beverage manufacturing company has been developed by using Mathematical Programming, and in particular, Integer Linear Programming to eliminate repetitive tasks (with high exposure of noise hazard) for each of the workers, while maintaining a constant level of production. This study was performed among 9 workers, and the proposed model was simulated under few scenarios based on machine availability and worker’s competency requirement. The proposed model was then transformed into MATLAB programming framework and the optimum solutions were then analysed to verify their effectiveness. Final results are given illustrating the validity and practicality of the proposed model for different operational scenarios

Determination of the range of safe-comfortable lifting postures using the aesthetic ergonomics theory

Past research indicates that, in general, individuals performing material handling tasks tend to underestimate lower back stress, i.e. L5/S1 disk compression, adopting free style lifting postures that often results a greater biomechanical stress in the lower back, increasing their potential risk of developing low back injuries in the short, mid and long terms.;The main objective of this research was to identify within theoretically safe workstation layouts, the subgroup of layouts that would lead workers to adopt cognitively comfortable and at the same time physically safe lifting postures. This research objective was achieved through the use of the Aesthetic Ergonomics Dual process discipline deployed in 2 interlinked stages: (1) the development, implementation and analysis of a survey where 121 experienced workers identified important cognitive factors and attributes which lead them to adopt perceived comfortable starting lifting postures in the sagittal plane, and (2) the design, implementation and analysis of a laboratory experiment where 20 workers experienced in material handling performed 12 different lifting, using a magnitude estimation scale to rate their perceived comfort at each lifting task. All lifting tasks were designed based on a lifting index, LI, which was set equal to one (1) according to the 1981 NIOSH Lifting guide.;Results of this study indicated that independent of horizontal reaches and container weights, workstations should be designed with a vertical height of approximately 30 inches. When compression and shear forces on the L5/S1 disc and subjects\u27 average heart rate were considered in the analysis, the results support the recommendation that 30 inches should be the preferred vertical height in the design of workstations where lifting is frequently performed. The highest vertical height evaluated, 45 , was associated with lifting tasks that posed a significantly higher physical demand on subjects\u27 shoulders, depicted as an inconsistency between subjects\u27 perceived comfort for 45 and this height\u27s corresponding average shear and compressive forces estimates for subjects\u27 L5/S1 disc. It was also found that average subject\u27s perceived comfort decreased as the weight of the object lifted increased, is independent of the horizontal distance of the lift. However, the weight of the object lifted resulted in a significant increase in the subjects\u27 estimated L5/S1 compression force with an increase in the height, which indicates that the counterpart nested factor in Zn, the horizontal distance, had a decreasing contribution as the vertical distance increased. In that matter, the vertical height found to have a greater potential impact on reducing the estimated L5/S1 was 30 inches

A method to design job rotation schedules to prevent work-related musculoskeletal disorders in repetitive work

This is an Accepted Manuscript of an article published by Taylor & Francis Group in International Journal of Production Research in 2012, available online: http://www.tandfonline.com/10.1080/00207543.2011.653452.Job rotation is an organisational strategy widely used in human-based production lines with the aim of preventing work-related musculoskeletal disorders (WMSDs). These work environments are characterised by the presence of a high repetition of movements, which is a major risk factor associated with WMSDs. This article presents a genetic algorithm to obtain rotation schedules aimed at preventing WMSDs in such environments. To do this, it combines the effectiveness of genetic algorithms optimisation with the ability to evaluate the presence of risk by repeated movements by following the OCRA ergonomic assessment method. The proposed algorithm can design solutions in which workers will switch jobs with high repeatability of movements with other less demanding jobs that support their recovery. In addition, these solutions are able to diversify the tasks performed by workers during the day, consider their disabilities and comply with restrictions arising from the work organisation.The authors wish to thank the Universitat Politecnica de Valencia which supported this research through its Program for the Support of Research and Development 2009 and its financing through the project PAID-06-09/2902.Asensio Cuesta, S.; Diego-Mas, JA.; Cremades Oliver, L.; González-Cruz, M. (2012). A method to design job rotation schedules to prevent work-related musculoskeletal disorders in repetitive work. International Journal of Production Research. 50(24):7467-7478. https://doi.org/10.1080/00207543.2011.653452S74677478502

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 127, April 1974

This special bibliography lists 279 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1974