Psychological and Physiological Features Associated with Swimming Performance

Background: The aim of the present research was to study the psychological and physiological features associated with aerobic and anaerobic performance in trained swimmers. Methods: A correlation and stepwise regression analyses were conducted with the data obtained in a RESTQ-76 sport questionnaire, a heart rate variability test, and an anaerobic and aerobic swimming performance efforts of 20 swimmers. Results: Aerobic performance correlated, principally, with parameters related to parasympathetic modulation measured in the frequency and time domains of the heart rate variability (LF/HF r: −0.806, p < 0.001; NN50 r: 0.937, p < 0.001). Swimmers’ anaerobic performance correlated to psychological features (low stress r: 0.526, p: 0.025, and high fatigue r: −0.506, p: 0.032). Conclusion: Swimming performance presented different psychological and physiological features depending on the probe characteristic. Specifically, swimmers’ anaerobic performance was associated with psychological features (low stress and high fatigue perception) and aerobic performance with physiological features (high parasympathetic modulation). This information could help coaches to know the variables to control in their swimmers, depending on the probe in which they compete (anaerobic or aerobic).

Diagnostics of low-pressure capacitively coupled RF discharge argon plasma

Low-pressure capacitively coupled RF discharge Ar plasma has been studied using Langmuir probe. The electron temperature, electron density and Debay length were calculated under different pressures and electrode gap. In this work the RF Langmuir probe is designed using 4MHz filter as compensation circuit and I-V probe characteristic have been investigated. The pressure varied from 0.07 mbar to 0.1 mbar while electrode gap varied from 2-5 cm. The plasma was generated using power supply at 4MHz frequency with power 300 W. The flowmeter is used to control Argon gas flow in the range of 600 standard cubic centimeters per minute (sccm). The electron temperature drops slowly with pressure and it's gradually decreased when expanding the electrode gap. As the gas pressure increases, the plasma density rises slightly at low gas pressure while it drops little at higher gas pressure. The electron density decreases rapidly with expand distances between electrodes.

About Hot-Wire Anemometer Applicability for Measurements in Nanopowder Flow

The paper is devoted to the detailed study of the hot-wire anemometer probe characteristic in the flow of silica nanopowder. The universal calibration graphs of hot-wire voltage and Nusselt number on the mean flow speed were determined. It was shown, that the hot-wire measures the speed fluctuations in nanopowder flow generally

The Effect of Al-17wt.%Si Alloy Melt Overheating on Solidification Process and Microstructure Evolution

The effect of overheating on the solidification process and microstructure evolution in AlSi17 silumin was discussed. The alloy melt was held for 40 minutes at 780, 860, 940 and 1020oC, and then cast at a temperature of 780oC to standard ceramic probe. Characteristic parameters of the AlSi17 alloy solidification process, especially Tliq, TE, Tsol, were determined. Examinations of microstructure were also carried out, showing that the higher was the overheating temperature, the higher was the degree of the primary silicon crystals refinement.