81,184 research outputs found

    The tangent splash in \PG(6,q)

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    Let B be a subplane of PG(2,q^3) of order q that is tangent to ℓ∞\ell_\infty. Then the tangent splash of B is defined to be the set of q^2+1 points of ℓ∞\ell_\infty that lie on a line of B. In the Bruck-Bose representation of PG(2,q^3) in PG(6,q), we investigate the interaction between the ruled surface corresponding to B and the planes corresponding to the tangent splash of B. We then give a geometric construction of the unique order-qq-subplane determined by a given tangent splash and a fixed order-qq-subline.Comment: arXiv admin note: substantial text overlap with arXiv:1303.550

    Exterior splashes and linear sets of rank 3

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    In \PG(2,q^3), let π\pi be a subplane of order qq that is exterior to \li. The exterior splash of π\pi is defined to be the set of q2+q+1q^2+q+1 points on \li that lie on a line of π\pi. This article investigates properties of an exterior \orsp\ and its exterior splash. We show that the following objects are projectively equivalent: exterior splashes, covers of the circle geometry CG(3,q)CG(3,q), Sherk surfaces of size q2+q+1q^2+q+1, and \GF(q)-linear sets of rank 3 and size q2+q+1q^2+q+1. We compare our construction of exterior splashes with the projection construction of a linear set. We give a geometric construction of the two different families of sublines in an exterior splash, and compare them to the known families of sublines in a scattered linear set of rank 3

    On the splash singularity for the free-surface of a Navier-Stokes fluid

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    In fluid dynamics, an interface splash singularity occurs when a locally smooth interface self-intersects in finite time. We prove that for dd-dimensional flows, d=2d=2 or 33, the free-surface of a viscous water wave, modeled by the incompressible Navier-Stokes equations with moving free-boundary, has a finite-time splash singularity. In particular, we prove that given a sufficiently smooth initial boundary and divergence-free velocity field, the interface will self-intersect in finite time.Comment: 21 pages, 5 figure

    Analysing splash in competitive diving

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    Splash size is an important factor in competitive diving and is considered to have a large effect in final judged scores. The aim of this research was to develop a system to determine the splash size during different stages of the dive entry. One diver was recorded during a training session and their dives analysed using the developed system. Three splash metrics were calculated at time of complete entry and maximum splash: (1) width of splash, (2) height of splash and (3) size of splash. Results indicated that there was no relationship between the splash metrics at complete entry and time of maximum splash. This may have implications for the scoring of a dive if the judge is unable to distinguish between these two splash events

    Current stage of the ATCA follow-up for SPLASH

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    Four ground-state OH transitions were detected in emission, absorption and maser emission in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH). We re-observed these OH masers with the Australia Telescope Compact Array to obtain positions with high accuracy (~1 arcsec). According to the positions, we categorised these OH masers into different classes, i.e. star formation, evolved stars, supernova remnants and unknown origin. We found one interesting OH maser source (G336.644-0.695) in the pilot region, which has been studied in detail in Qiao et al. (2016a). In this paper, we present the current stage of the ATCA follow-up for SPLASH and discuss the potential future researches derived from the ATCA data.Comment: 2 pages, conference, IAU symposium 33

    Potential use of BEST® sediment trap in splash-saltation transport process by simultaneous wind and rain tests

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    The research on wind-driven rain (WDR) transport process of the splash-saltation has increased over the last twenty years as wind tunnel experimental studies provide new insights into the mechanisms of simultaneous wind and rain (WDR) transport. The present study was conducted to investigate the efficiency of the BEST® sediment traps in catching the sand particles transported through the splash-saltation process under WDR conditions. Experiments were conducted in a wind tunnel rainfall simulator facility with water sprayed through sprinkler nozzles and free-flowing wind at different velocities to simulate the WDR conditions. Not only for vertical sediment distribution, but a series of experimental tests for horizontal distribution of sediments was also performed using BEST® collectors to obtain the actual total sediment mass flow by the splash-saltation in the center of the wind tunnel test section. Total mass transport (kg m-2) were estimated by analytically integrating the exponential functional relationship using the measured sediment amounts at the set trap heights for every run. Results revealed the integrated efficiency of the BEST® traps at 6, 9, 12 and 15 m s-1 wind velocities under 55.8, 50.5, 55.0 and 50.5 mm h-1 rain intensities were, respectively, 83, 106, 105, and 102%. Results as well showed that the efficiencies of BEST® did not change much as compared with those under rainless wind condition
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