Operational Considerations for Tube Bundle Gas Monitoring Systems

Tube bundle gas monitoring systems are now common practice in the Australian underground coal mining industry. Systems are in operation at all underground coal mines in Queensland, all longwall coal mines in New South Wales, and most bord and pillar coal mines in New South Wales. This paper utilises the information assessed by Simtars as part of the project “The Application of Tube Bundle Systems in the Prevention of Mine Fires and Explosions and Post-Event Response”, prepared for the National Institute for Occupational Safety and Health (NIOSH), under contract number 200-2013-56949. The operational considerations and decisions required to ensure the optimum operation of the system will be outlined. Installation, maintenance, training requirements, alarm settings and interpretation of the gas results will be taken into account. Practical solutions and explanations will be provided, drawing on Australian and overseas experience, as well as information publicised by the National Coal Board in the United Kingdom and the United States Bureau of Mines (USBM)

Bimanual finger tapping: effects of frequency and auditory information on timing consistency and coordination

The authors' goal in this study was to probe the basis for an earlier, unexpected finding that preferred-frequency finger tapping tends to have higher frequencies and to be less stable for in-phase than for antiphase tasks. In follow-up experiments, 3 protocols were employed: a preferred-frequency replication in both coordination modes, a metronome-driven matching of the preferred frequencies to each of the coordination modes, and a frequency scaling of both modes. The original findings were affirmed for preferred frequency. Tapping to a metronome had a differential effect on in-phase and antiphase: A more stable coupling across frequencies was exhibited during in-phase. Under frequency scaling, the antiphase pattern decomposed at lower frequencies than did in-phase, but no phase transitions were observed. The loss of stable coordination in both modes was attended by sudden increases in frequency differences between fingers and by phase wandering. The emergence of those effects is discussed in light of asymmetric modifications to the Haken-Kelso-Bunz model (H. Haken, J. A. S. Kelso, & H. Bunz, 1985) and the task constraints of tappin

The effect of nonspecific task constraints on quadrupedal locomotion: II. Joint kinematics

The effects of directional and postural constraints on preferred speed quadrupedal gait patterns were studied by comparing responses to four hand-foot crawling tasks: forward and backward prone (FP and BP) and forward and backward supine (FS and BS). A central question was whether the task dynamics evident at the end-effector level also appear at the joint effector system level. Timing of reversals in each limb's proximal effector system joints was shown to be related to the functional role (propulsion or reaching) of the limb. Within joints, task constraint changes strongly tended to affect reversal times, and time-reversed directional comparisons tended to show "mirroring" responses. Peak reaching positions were also closely associated with forelimb touchdowns and interlimb coordination. Discussion centers on task function, task dynamics, and their influence on effector system behavio

Dual-finger preferred-speed tapping: effects of coordination mode and anatomical finger and limb pairings

Interlimb and interfinger coordination were examined on a dual-finger tapping paradigm in which 16 subjects performed at preferred frequencies. Three bimanual finger combinations, in random order (2 index; 2 middle; and 1 index and 1 middle), were performed in in-phase and antiphase coordination modes, in addition to 1 unimanual combination (antiphase index middle). Relative phase means were within 3% accuracy for all conditions. A lower tapping frequency was found in all antiphase vs. in-phase conditions, accompanied by lower phasing variability and lower intrafinger consistency in the antiphase. When frequency was changed from the preferred rate, the 2 coordination modes became more alike in variability and, within the same frequency range, demonstrated no significant differences. The bimanual mixed-fingers tapping tended to have significantly lower phasing values (a small fixed point drift) and higher tapping frequencies than the symmetric conditions. The unimanual task was similar to all other antiphase conditions. Changes in preferred frequency with different coordination modes may be related to differing perceptual informational constraints. Current models addressing natural frequencies of coupled oscillators do not account for the present dat

The effect of nonspecific task constraints on quadrupedal locomotion: I. Interlimb coordination

The present study examined the effect of nonspecific task constraints on the multilimb coordination task of preferred-speed crawling. Adult subjects undertook three trials each of the following randomly ordered conditions: forward prone (FP), backward supine (BS), backward prone (BP) and forward supine (FS). Subjects adopted specific coordinative solutions consistent with task-related function rather than anatomical specification. The patterns were relatively stable, with BP being least stable. Across conditions, subjects changed their velocity in a predictable order that corresponded to the various constraints. These velocity changes were largely attributable to stride length adjustments and not limb frequency. Within a condition, neither velocity nor anthropometrics appeared to influence the coordinative solution. Overall, rather large differences were found in coordinative solutions, possibly owing to the nature of the tasks and/or individual searching strategies. The results were interpretable within a dynamic approach to coordination and support the idea that coordination is functionally rather than anatomically determine

A note on time-frequency analysis of finger tapping

Finger tapping involves 3 important features: time, spatial amplitude, and frequency. In classical analysis, investigators examine timing parameters; in spectral analysis, they examine frequency parameters. Both types of analysis are based on stationary tap information. The authors propose that time-frequency analysis is a useful tool for analyzing nonstationary finger tapping. They describe the method and give examples of frequency modulation, age difference, and speed transition that demonstrate additional insights one can gain by using this analysi

Individual differences and similarities in the stability, timing consistency, and natural frequency of rhythmic coordinated actions

Under preferred speed conditions, 15 adults undertook bimanual in-phase and antiphase tapping, clapping, galloping, galloping while clapping, and crawling on their hands and feet. We measured stability of interlimb coordination (standard deviation of mean interlimb relative phasing), single limb timing consistency (coefficient of variation of mean single limb cycle durations), and natural limb frequency. Pearson product-moment correlations among tasks established that only the natural limb frequencies were significantly correlated (specifically among gross motor actions in which larger contributions of inertial loads contribute to natural frequencies). Intraclass correlations were high for tasks, meaning that within each task, all participants performed similarly. Thus, only frequency has a tendency to show a common time-based process within a participant, but common time-based processes exist between participant