| 1. |
- Chen, F., et al.
(author)
-
Evaluation of a workstation for letter sorting in the Beijing post office
- 1993
-
In: Occupational and environmental economics. - : Indian Society of Ergonomics.. - 819005080X ; , s. 61-66
-
Conference paper (peer-reviewed)abstract
- In the Chinese postal system, letters are sorted manually using a sorting frame, consisting of vertical and horizontal arrays of pigeon-holes of different dimensions. Letter sorting is a time consuming and a mentally intensive task involving repetitive movements of shoulder and hand muscles. Musculoskeletal complaints and disorders of the lower back, shoulder and hand occur frequently among the letter sorting workers. A total of 293 letter-sorters (71 males and 222 females) from Beijing Postal Sorting Office were subjected to a general health check-up including musculoskeletal disorders coupled with administration of a questionnaire. The worker's daily work load was evaluated by counting the number of letters sorted in each pigeon-hole in the sorting frame and also by considering their arm movements and body postures. The workplace dimensions were also measured. Results revealed that 62.1% of the workers complained of low back pain, 78.5% of shoulder pain and 48.8% of hand pain. A high percentage of workers seemed to have mental intensive symptoms, such as, headache, dizziness and drowsiness. Almost 25% of the female wokers indicated irregularity in their menstruation. An improved ergonomic design of the sorting frame is recommended.
|
|
| 2. |
|
|
| 3. |
- Li, Wen-Bin, et al.
(author)
-
Instantaneous and residual stresses developed in hot isostatic pressing of metals and ceramics
- 1991
-
In: Metallurgical and Materials Transactions. A. - 1073-5623 .- 1543-1940. ; 22:5, s. 1071-1078
-
Journal article (peer-reviewed)abstract
- Under many conditions, hot isostatic pressing (HIP) of metallic or ceramic porous preforms occurs by the densification of a shell at the surface of the preform, which then thickens until the whole sample is fully densified. The development of such a dense shell reduces the effective pressure acting to densify the remaining porosity. Furthermore, this pressure difference can lead to anisotropic creep of the shell, and this may be a contributary cause of shape change of samples during HIP. The stresses occurring during cooling of the sample and the residual stresses are calculated as a function of all of the various material and pressing parameters. It is found that, in many cases, the cooling stresses which are tensile at the surface may well be large enough to cause cracking in ceramic samples
|
|
