There is evidence of a statistically significant increase in Ht over the course of a single warm-water scuba dive. This increase is small and is within the range of error associated with the techniques of Ht estimation employed in this study. Depth exposure was found to correlate with Ht increase. In view of the small magnitude of change in the Ht, there is no reason to amend protocols for fluid resuscitation of recreational scuba divers suspected to have experienced decompression injury in tropical locations.

No abstract

The rate of heat transfer to the mold during solidification determines the cooling rate of castings, which significantly impacts their characteristics. The use of an insert produced by additive manufacturing in the mold, with appropriately designed cooling channels, enables adequate cooling control of the entire piece. This article investigates the heat transfer properties at the interface between two types of steel used for die casting molds (steel A) and additively manufactured cooling inserts (steel B). The study analyzed the impact of coolant water flow rate channel (215, 300, and 425 mL/min.) and contact pressure between the two types of steel (0, 15, and 30 bar) on the thermal behavior of the mold/insert assembly in both transient and steady states. The time constants of the system associated with the coolant flow rate transitions from 215 to 300 mL/min and from 215 to 425 mL/min were determined during the transient mode. The findings indicated that increasing the proximity of the cooling channel to the interface, coolant flow rate, and contact pressure resulted in a faster cooling response in the transient state. For the tested conditions, the determination of thermal contact resistance (TCR) was carried out in the steady state. The TCR values were affected by the contact pressure between the two steel pieces, showing, with an increase of 30 bar, a decrease of 21% and 33% for cooling channels located at 6.5 and 9.5 mm from the interface, respectively. Within the tested range, the TCR values were not significantly affected by variations in cooling flow rates. Lower TCR values were observed when the cooling channel was positioned closer to the interface (~ 28%). The study provides valuable insights into the factors affecting thermal contact resistance and process parameters. It can aid in optimizing cooling insert design for casting molds, namely by numerical analysis.

No abstract

Fatigue strength properties of welded joints of high-strength weldable structural steel.Particularly with regard to weld joints, high-strength and super high-strength structural steels under unfavourable boundary conditions is hardly superior to normal-strength steel. These studies aim at analyzing whether the fatigue strength characteristics of butt joint and cruciform joint samples can be improved by optimizing the weld seam geometry and by subsequent mechanical treatment by shot peening with ceramic balls or with steel scraps, and at determining which difficulties may occur during this process. The practical tests were supported and completed by theoretical calculations according to the FE-method. A final comparison with the standards will illustrate the difficulties in determining admissible fatigue strength values of weld joints.