Heart Rate Variability and Direct Current Measurement Characteristics in Professional Mixed Martial Arts Athletes

This study’s purpose was to examine heart rate variability (HRV) and direct current potential (DC) measures’ sensitivity and correlations between changes in the acute recovery and stress scale (ARSS) and the previous day’s training load. Training load, HRV, DC and ARSS data were collected from fourteen professional mixed martial arts athletes (32.6 ± 5.3 years, 174.8 ± 8.8 cm, 79.2 ± 17.5 kg) the following morning after hard, easy and rest days. Sensitivity was expressed as a signal-to-noise ratio (SNR, inter-day typical error (TE) or coefficient of variation (%CV) divided by intra-day TE or %CV). Correlations between HRV, DC and ARSS with training load were also examined. The SNRs for the various HRV and DC measures were acceptable to good (1.02–2.85). There was a 23.1% CV average increase between measures taken between different locations versus the same location. Training load changes were not correlated with HRV/DC but were correlated with ARSS stress variables. Practitioners should be aware of HRV/DC variability; however the daily training signal was greater than the test-retest error in this investigation. Upon awakening, HRV/DC measures appear superior for standardization and planning. HRV and DC measures were less sensitive to the previous day’s training load than ARSS measures.

Structural, Morphological and Electrical Properties of CdO Thin Film Produced by Sol–Gel Spin Coating Procedure

A sol–gel spin coating procedure was used to produce cadmium oxide (CdO) thin film on the precleaned glass substrate. The structural, morphological and electrical properties of the produced film were specified by XRD, SEM and two-probe method. The polycrystalline nature with cubical structure of the cadmium oxide (CdO) thin film was confirmed by X-ray diffraction (XRD). Scanning electron microscope (SEM) confirms the uniform formation of film. The semiconducting character of the film was confirmed by electrical conductivity (direct current) measurement in dark. The Hall effect measurement of cadmium oxide film confirms the n-type conductivity.

A Direct Current Measurement Method Based on Terbium Gallium Garnet Crystal and a Double Correlation Detection Algorithm

When applying an optical current transformer (OCT) to direct current measurement, output signals exhibit a low signal-to-noise ratio and signal-to-noise band overlap. Sinusoidal wave modulation is used to solve this problem. A double correlation detection algorithm is used to extract the direct current (DC) signal, remove white noise and improve the signal-to-noise ratio. Our sensing unit uses a terbium gallium garnet crystal in order to increase the output signal-to-noise ratio and measurement sensitivity. Measurement errors of single correlation and double correlation detection algorithms are compared, and experimental results showed that this measurement method can control measurement error to about 0.3%, thus verifying its feasibility.

Use of cross-compiling in the programming of an intelligent device for measuring electrical quantities

A device for voltage and direct current measurement, built by coupling a Raspberry Pi microcomputer with an Arduino series microcontroller is presented in this paper. The structure of the device is presented and the method of implementing proprietary programs for both devices is described. A touch screen of the device allows the user to decide on the measurement mode (automatic or manual) and on the method of archiving and visualizing the effects of measurements. The application uses the so-called cross-compiling, thanks to which it is possible to effectively couple such different platforms as Raspberry Pi and Arduino.