Examination of space/volume requirements for US underground coal mine refuge alternatives
ABSTRACT The Mine Safety and Health Administration requires that 1.4 m2 (15 ft2) of floor space is to be provided for each person inside a refuge alternative (RA). However, the amount of floor space needed for a person to reside inside an RA and perform basic tasks is unknown. During testing, participants entered into an RA or a simulated RA of various space/volume configurations and performed several simulated tasks that are representative of the survivability tasks performed within an RA. The results indicate that the floor space requirements were generally adequate for the tasks studied. Certain tasks such as changing scrubber cartridges, using toilets, and moving about the RA were impacted by the minimum height tested (0.6 m). As such, RAs of this height will require critical design consideration as a whole and the supplies provided for use inside of the RA to ensure the ability to use an RA.
The Effects of Ejection Seat Cushion Design on Physical Fatigue and Cognitive Performance
Abstract : The detrimental effects of prolonged sitting during long-duration flights include deep vein thrombosis, pressure sores, and decreased awareness and performance. However, the cushion is often the only component of the ejection seat system that can be modified to mitigate these effects. This study investigated the long-duration effects of sitting in four ejection seat cushions over eight hours. Subjective comfort survey data and cognitive performance data were gathered along with comparative objective data, including seated pressures, muscular fatigue levels, and lower extremity oxygen saturation. Peak seated pressures ranged from 1.22-3.22 psi. Oxygen saturation in the lower extremities decreased over the eight hours. Cognitive performance increased over time regardless of cushion with the exception of the dynamic cushion, which induced a decrease in performance for females. Muscular fatigue increased throughout the eight hours regardless of cushion, with the exception of the dynamic cushion which promoted muscular recovery. Subjective comfort levels declined over the eight hours. Subjective measurements correlated with objective parameters for the static cushions. Trade-offs in performance and fatigue mitigation were apparent in the dynamic cushion which also highlighted the differences between genders. These results will be used to develop cushion design guidelines, both to prevent deep vein thrombosis and to promote performance and comfort for long-duration use.
Standing balance in healthy subjects. Evaluation of a quantitative test battery on a force platform.
A quantitative battery of tests for standing balance is needed in the assessment of functional impairments. The aims of the present study were to obtain stabilometric reference values for healthy females and males, 20-64 years of age, on a stable computerized force platform (AMTI) and to relate the balance data thus obtained to some traditional functional balance tests. Altogether, 152 subjects performed a series of tests. The test battery on the force platform comprised tests of standing with feet close together or on one leg while looking straight ahead or while blindfolded. Traditional functional balance tests were checked and various background data were collected through a questionnaire. Results of a separate test-retest reliability study of the test battery given on the force platform appeared promising, especially for the tests with eyes open. In the main study, results obtained on the force platform correlated significantly (p less than 0.001) with results of most of the functional tests. Women showed higher standing balance as compared with men. The results suggest the importance of relating the test-data not only to age but also to sex.