Development of Calculating Grinding Wheel-Profile Software Applied to the Sharping Grinder Machine

The grinding wheel-profile is mostly formed by adjusting the angle of cylindrical profile model when regrinding gear hob with the large helix flute. Repeat trial cutting is needed with this method, which results in low efficiency. In order to improve the efficiency of processing, a mathematical model of grinding wheel profile was establish in according to forming principle of the rake face of gear hob and accurately calculate grinding wheel-profile. A automatic programming system of calculating grinding wheel-profile and automatically generate NC code is developed with the developing tool of VC++.

Human thermoregulatory responses during serial cold-water immersions

This study examined whether serial cold-water immersions over a 10-h period would lead to fatigue of shivering and vasoconstriction. Eight men were immersed (2 h) in 20°C water three times (0700, 1100, and 1500) in 1 day (Repeat). This trial was compared with single immersions (Control) conducted at the same times of day. Before Repeat exposures at 1100 and 1500, rewarming was employed to standardize initial rectal temperature. The following observations were made in the Repeat relative to the Control trial: 1) rectal temperature was lower and heat debt was higher ( P < 0.05) at 1100; 2) metabolic heat production was lower ( P < 0.05) at 1100 and 1500; 3) subjects perceived the Repeat trial as warmer at 1100. These data suggest that repeated cold exposures may impair the ability to maintain normal body temperature because of a blunting of metabolic heat production, perhaps reflecting a fatigue mechanism. An alternative explanation is that shivering habituation develops rapidly during serially repeated cold exposures.