Characteristic analysis of journal bearing under thin film lubrication—Layered Viscosity Model
Journal bearing is a kind of widely used bearing and its study never stops. The analysis is carried to journal bearing with layered viscosity model in this paper. Layered Viscosity Model regards viscosity as piecewise function and averages every segment in order to get more accurate expression, and the pressure distributing, load capacity and friction are obtained for journal sliding bearing under thin film lubrication. The condition of thin film lubrication actualizing is made certain. The theoretical base is provided for the analysis of aggradation and liniment surface layer lubrication. This work could promote the understanding and research of the mechanism of the nano - scale thin film lubrication.
Numerical Study of Slider Bearings With Limited Corrugation
Influence of corrugation of limited extent on the performance of fixed-incline slider bearings of infinite width is investigated numerically. Effects of the corrugated section's parameters like its location, length, and corrugation amplitude, on pressure distribution in the bearing's fluid film, its load supporting capacity W and flow rate, are considered. When this section is near the entrance to the bearing gap, pressure and W are reduced in comparison with the smooth wall case. As this section is located further downstream, peak pressure and W increase, whereas flow rate decreases. These effects are reinforced by longer corrugated section and larger corrugation amplitude. The results thus point to a simple way to substantially enhance a bearing's load-supporting capacity.
Mottle on computed radiographs of the chest in pediatric patients.
PURPOSE
To investigate the relationship between radiation exposure and perceived mottle at bedside pediatric chest examinations performed with screen-film and computed radiographic techniques.


MATERIALS AND METHODS
In a pediatric intensive care unit, chest radiographs were obtained with both computed radiography (60 radiographs) and a 600-speed screen-film system (14 radiographs). The relative radiation exposure was estimated by using the sensitivity value obtained in the processing of each computed radiograph. Five radiologists assessed the mottle present in the computed radiographs and screen-film images.


RESULTS
For computed radiographs, the perceived level of mottle was inversely related to radiation exposure. For the same radiation exposure, the perceived mottle on computed radiographs was significantly higher than that on screen-film images (P < .001 for small cassettes; P < .01 for large cassettes).


CONCLUSION
Pediatric computed radiography of the chest requires approximately twice the exposure of a 600-speed screen-film system to attain the same level of mottle.