![]() The calculated intensities were compared with those derived from focal peak pressure measurements made using a calibrated hydrophone. ![]() Spatial- peak intensities were estimated for 8 transducers at three drive powers levels: low (approximately 1 W), moderate (~10 W) and high (20-70 W). 20 259-69), (ii) a numerical method derived from theory, (iii) a method using measured sidelobe to focal peak pressure ratio, and (iv) a method for measuring the focal power fraction (FPF) experimentally. Four methods are compared: (i) a solid spherical bowl approximation (after Hill et al 1994 Ultrasound Med. Improved strategies for determining focal peak intensity from a measurement of total acoustic power are proposed. A hole in the centre of the transducer results in over-estimation of the peak intensity. This paper demonstrates theoretically and experimentally that this expression is only strictly valid for spherical bowl transducers without a central (imaging) aperture. 20 259-69) provided a simple equation for estimating spatial- peak intensity for solid spherical bowl transducers using measured acoustic power and focal beamwidth. These data provide further knowledge of the peak activity profiles of international rugby competition, and this information can be used to assist coaches and practitioners in adequately preparing athletes for the most demanding periods of play.įocused ultrasound transducer spatial peak intensity estimation: a comparison of methodsĬivale, John Rivens, Ian Shaw, Adam ter Haar, GailĬharacterisation of the spatial peak intensity at the focus of high intensity focused ultrasound transducers is difficult because of the risk of damage to hydrophone sensors at the high focal pressures generated. The current study has presented a framework to describe the peak running intensities achieved during international rugby competition by position, which are considerably higher than previously reported whole-period averages. Halfbacks demonstrated the greatest relative distance and P met outputs but were similar to outside backs and loose forwards in AveAcc demands. P met demands were at least likely greater for outside backs and halfbacks than for the tight 5 (ES = 0.86-0.99). There were likely small to moderate increases in relative distance and AveAcc for outside backs, halfbacks, and loose forwards compared with the tight 5 group across all moving-average durations (effect size = 0.27-1.00). Peak running intensity increased as the length of the moving average decreased. Differences between positions and durations were described using a magnitude-based network. A moving-average approach was used to identify the peak relative distance (m/min), average acceleration/deceleration (AveAcc m/s 2 ), and average metabolic power (P met ) for a range of durations (1-10 min). Global positioning systems (GPS) were used to assess the activity profile of 67 elite-level rugby union players from 2 nations across 33 international matches. To quantify the duration and position-specific peak running intensities of international rugby union for the prescription and monitoring of specific training methodologies. Peak Running Intensity of International Rugby: Implications for Training Prescription.ĭelaney, Jace A Thornton, Heidi R Pryor, John F Stewart, Andrew M Dascombe, Ben J Duthie, Grant M Using two different methods, the peak current near ground in these dart leaders is estimated to range from 0.1 to 6 kA. In addition, the peak relative intensity near ground is evaluated for 22 dart leaders, and a mean ratio of peak dart leader to peak return stroke relative light intensity was found to be 0.1 with a range of 0.02-0.23. The correlation between L(R) and the maximum rate of current rise is also examined, but less correlation than between L(R) and I(R) is found. Although a relation between L(R) and I(R) is evident in these data, none of the analytical relations considered is clearly favored. Correlations, significant at better than the 0.1 percent level, were found for several functional relationships. The measurements of peak relative light intensity were obtained from photographic streak recordings using calibrated film and microsecond resolution. One flash contained 19 strokes and the other 20 strokes for which direct measurements were available of the return stroke peak current at ground. The correlation between peak relative light intensity L(R) and stroke peak current I(R) is examined for 39 subsequent return strokes in two triggered lightning flashes. ![]() Correlated peak relative light intensity and peak current in triggered lightning subsequent return strokes
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