Proposition of Thermal-Diffusion-Induced Spiral Model for the Rapid Oil-Film Breakdown Process during Scuffing

Tribological characteristics of Al-Si alloy impregnated graphite composite (ALGR-MMC) in contact with bearing steel were investigated under insufficiently lubricated reciprocating sliding conditions. Ball (JIS SUJ2 bearing steel) on disk (ALGR-MMC) type wear tests were conducted under unlubricated conditions, i.e., in air with high (70%) and low (≤ 1%) relative humidity (RH), under drop-feed lubrication, i.e., oil-drops were deposed on the disk surface before commencing the tests, and under immersion lubrication, i.e., the ball-on-disk contact was submerged in a oil (SAE30) bath. Reciprocating sliding movement was maintained, under a contact load of 40 N at a frequency of 3.3 Hz and amplitude of 3.5 mm, for 100,000 cycles. Tribological properties were continuously monitored. Variation of the kinetic friction coefficient (KFC) versus the number of reciprocating cycles (NRC) was obtained for various amounts of oil (lubrication conditions) and two values of the air RH. For drop-feed lubrication the KFC has at beginning the same value as that under immersed lubrication, but if breakdown of the oil film has occurred after a certain NRC, it increases towards the value corresponding to unlubricated conditions. Connected to the oil film breakdown, there is a certain transition range, expressible both in terms of the oil amount and NRC. Minimum quantity of oil to avoid the film breakdown was found. Due to its self-lubricating properties, ALGR-MMC was able to endure adverse lubrication conditions such as insufficiently lubricated reciprocating sliding.

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Hostile and Hardened? An Experimental Study on (De-)Sensitization to Violence and Suffering Through Playing Video Games

Swiss Journal of Psychology ◽

10.1024/1421-0185.67.1.41 ◽

2008 ◽

Vol 67 (1) ◽

pp. 41-50 ◽

Cited By ~ 24

Author(s):

Frithjof Staude-Müller ◽

Thomas Bliesener ◽

Stefanie Luthman

Keyword(s):

Video Games ◽

Emotional Responses ◽

Physiological Measurement ◽

Different Types ◽

Downward Spiral ◽

Spiral Model ◽

Post Hoc ◽

Game Violence ◽

First Person Shooter ◽

Physiological Reactions

This study tests whether playing violent video games leads to desensitization and increased cardiovascular responding. In a laboratory experiment, 42 men spent 20 min playing either a high- or low-violence version of a “first-person shooter” game. Arousal (heart rate, respiration rate) was measured continuously. After playing the game, emotional responses to aversive and aggressive stimuli - pictures from Lang, Bradley, and Cuthbert’s (1999) International Affective Picture System - were assessed with self-ratings and physiological measurement (skin conductance). Results showed no differences in the judgments of emotional responses to the stimuli. However, different effects of game violence emerged in the physiological reactions to the different types of stimulus material. Participants in the high-violence condition showed significantly weaker reactions (desensitization) to aversive stimuli and reacted significantly more strongly (sensitization) to aggressive cues. No support was found for the arousal hypothesis. Post-hoc analyses are used to discuss possible moderating influences of gaming experience and player’s trait aggressiveness in terms of the General Aggression Model ( Anderson & Bushman, 2001 ) and the Downward Spiral Model ( Slater, Henry, Swaim, & Anderson, 2003 ).

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