Papers by Keyword: Direct Observation

Abstract: Engineers in the communication and multimedia industries in Malaysia exposed to the risk factors of work-related musculoskeletal disorders. A comprehensive study was conducted to perform ergonomic studies for indoor spectrum measurement activity to improve productivity and occupational safety and health. The study consisted of two phases, where the participative assessments and direct observations were conducted on 17 engineers. In the first phase, the indoor spectrum measurement problem identification was performed by using the portable and handheld spectrum analyser. The questionnaire, body part assessments and archival operation records were investigated. In the second phase, the ergonomics intervention was introduced with a low-cost trolley that removed the work-related musculoskeletal disorders from the engineers. The same test subject, environments, work procedures and evaluation method in phase one were repeated in phase two. The analysis was done by comparing the findings between both phases through statistical analysis, and the significant improvements of ergonomic interventions were identified. The outcome of the study concluded that the analysis and results meet the main objective.

Abstract: This paper emphasizes an ergonomics intervention to fit jobs for workers in the handling of air handler panels in a manufacturing factory. Ergonomic risk factors were identified by means of qualitative and quantitative data from general survey, participative assessments, and direct observations. Ergonomics intervention via real life experiment was implemented. Post survey incorporating participative assessments and direct observations was subsequently conducted to gauge its effectiveness. This intervention comprises the introduction of a steel trolley for horizontal placing of steel panels and a mobile steel rack for vertical placing of those panels. This action-oriented study produced results which were in line with the objective of the research.

Abstract: Although several computer simulation codes have been developed to predict and prevent defects of lost foam castings, most of them are focused on aluminum alloy castings. This paper presents a new simulation method suitable for not only aluminum alloy but also cast iron. First of all, main assumptions and numerical schemes are as below: 1) Gas flow in the mold follows the D’Arcy’s law. 2) The gas pressure in the kinetic zone (gas gap) is uniform in each gas group and is solved by using the flow field of melt one time-step before. 3) The gas obeys the ideal gas law. 4) Latent heats of evaporative pattern degradation are simplified by an overall latent heat in which both melting and evaporation are considered. 5) The pattern absorbs heat of melt through conduction, radiation and convection. Further, X-ray direct observations of mold filling behaviors of cast iron were carried out in order to better understand the physical fundamentals and to evaluate simulated results. It was found that: 1) Mold filling behaviors of cast iron are quite different from those of aluminum alloy castings depending on the gating system and thickness of the casting. 2) Bubble floating-up often occurred in the case of the downward flow. 3) Although the newly developed simulation code could predict the mold filling to some extent, further work needs to be done, including better understanding of the heat transfer mechanism between the melt and pattern.

Abstract: Asymmetric rolling has been considered as a possible way to obtain severe plastic deformation (SPD) since it will give an extra shear deformation to the processed materials during rolling. Previous researches have confirmed such a shear deformation. Very recently, the method of inserting-block is used to characterize the shear deformation through direct observation, but when the reduction is more than 70%, the lineation scratched on the side face of internal mark becomes vague and illegible. In order to directly observe the shear deformation of metallic material with large reduction, the internal mark method is employed in this research and asymmetric rolling was performed with pure aluminum and iron at room temperature. In severe plastic deformation, the shear deformation caused by asymmetric rolling was clearly observed and measured through employing internal mark method. Remarkable extra shear deformation during asymmetric rolling was confirmed. Very high equivalent strains were achieved when sheet samples were asymmetrically rolled to high reduction ratio. These strain values fall into the range of SPD.