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.
Lifting in four restricted lifting conditions: psychophysical, physiological and biomechanical effects of lifting in stooped and kneeling postures.
Many underground coal mines are less than 1.2 m in height, and require that manual lifting tasks be performed in restricted postures (usually stooped or kneeling). Unfortunately, little is known about how these postures affect the underground coal miner's capabilities to perform such work. A previous Bureau of Mines study indicated that lifting capacity is greater when stooped than kneeling when lifting under a 1.2 m roof height (Gallagher et al, 1988). However, many low-seam coal mines present even more restricted headroom than 1.2 m. Therefore, a study was conducted to: (1) examine the psychophysical lifting capacity of low-seam coal miners under four restricted lifting conditions, (2) investigate the associated metabolic costs, and (3) analyse the electromyography (EMG) of trunk muscles when lifting in these restricted positions. Subjects were 12 coal miners accustomed to handling materials in restricted postures (mean age = 35.9 yrs +/- 6.4 SD). Results of this study indicated that lifting capacity was greater when the subjects could assume a stooped posture than when kneeling (p < 0.01). Furthermore, the metabolic cost was greater in the kneeling posture for heart rate (p < 0.001), oxygen consumption (p < 0.001), minute ventilation (p < 0.05] ), and respiratory exchange ratio (p < 0.05), despite the fact that miners lifted less weight in this posture. Analysis of the EMG data indicated increased activity of the electores spinae when kneeling (p < 0.001), but higher latissimus dorsi activity when stopped (p < 0.001). The findings of this study indicate that the weight of supply items should be reduced approximately 14-18% when the kneeling posture must be used for lifting.
CAUSES OF FLUCTUATIONS IN R&D EXPENDITURES A QUANTITATIVE ANALYSIS
Introduction 124 The stylised facts of R&D in OECD economies 124 The determinants of business R&D expenditures 127 Modelling R&D expenditures 130 Conclusion 135 Bibliography 137 Annex: The model 138