No abstract

No abstract

Dynamic separation phenomena in spring-supported rotary face seals are studied, employing a mathematical model which simulates the dynamic response characteristics of the system. Parameters considered in the model include support resilience, amplitude of shaft pulsation and mating ring wobble, initial preset, operating frequency, and contact surface friction. Inclusion of contact friction necessitates consideration of dynamic coupling in the equations governing the motion of the seal carrier. Combinations of operating conditions and system variables which produce incipient mechanical separation are predicted by examining the behavior of the contact force distribution between the seal and mating ring. Equations and graphs are presented which specify the theoretical preset required to maintain continuous contact as a function of the system parameters considered in the analysis.

The present research was concerned with whether the occurrence of habituation to auditory stimuli during sleep might attenuate the disruptive effects these stimuli can have on waking performance. Human subjects were exposed on different nights to either 0, 6, or 24 presentations of a 15-sec burst of filtered auditory noise, and their morning waking performance was measured by a reaction-time task previously shown to be sensitive to minimal sleep disturbances. The results indicated that on nights when 24 stimuli were presented, the subjects' average arousal response was significantly less as compared to the nights when only 6 stimuli were presented, thus demonstrating the occurrence of habituation. However, the decreased average arousal when 24 stimuli occurred was not associated with superior morning performance. On the contrary, the subjects performed significantly better following the nights when only 6 stimuli occurred even though the average arousal associated with the stimulus presentations was significantly greater. The data thus suggest that the relation between sleep disruption and waking performance is a function of not only the arousal produced by the individual stimulus occurrences but also, and perhaps more importantly, the number of stimuli occurring during the night. Recent evidence has suggested that minimal sleep disturbances can have effects on waking behavior and that it is possible to detect these effects with a simple reaction-time memory task soon after an individual awakens (LeVere, Bartus, & Hart, 1972). Since waking

Mechanical separation between cam and pick ball in fly-shuttle looms gives rise to impact and vibration which causes significant noise emission. Elimination of separation is analyzed using a mathematical model which simulates the dynamic response characteristics of the system. Parameters considered in the study include equivalent stiffness, mass, and damping of the system, amplitude of excitation, effect of preload provided by a retaining spring, and operating frequency. Combinations of system parameters and operating conditions which give rise to separation are predicted by examining the contact force developed between cam and cam-follower. Equations and graphs are presented that specify the preload required to eliminate separation as a function of the system parameters.