28,577 research outputs found

    Exercise Technique: Reverse Lunge into a Step-Up

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    THE TECHNIQUE OF A REVERSE LUNGE INTO A STEP-UP IS DESCRIBED AND DEMONSTRATED THROUGH THE USE OF PHOTOGRAPHS IN THIS COLUMN. AN EXERCISE PRESCRIPTION IS GIVEN

    A Conditioning Program for Skill Positions Using Lunge Variations

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    Prone Torso Rotation Exercise Using a Stability Ball

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    THIS COLUMN PROVIDES A DETAILED DESCRIPTION AND PHOTOGRAPHS OF THE PROPER EXERCISE TECHNIQUE FOR A PRONE TORSO ROTATION EXERCISE USING A STABILITY BALL

    Alternating Inchworm and Pike from a Plank Exercise Using a Stability Ball.

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    THE TECHNIQUE OF THE ALTERNATING INCHWORM AND PIKE FROM A PLANK EXERCISE USING A STABILITY BALL IS DESCRIBED AND DEMONSTRATED IN THIS COLUMN

    EFFECTS OF AL(2)O(3) NANOPARTICLES DEPOSITION ON CRITICAL HEAT FLUX OF R-123 IN FLOW BOILING HEAT TRANSFER

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    In this study, R-123 flow boiling experiments were carried out to investigate the effects of nanoparticle deposition on heater surfaces on flow critical heat flux (CHF) and boiling heat transfer. It is known that CHF enhancement by nanoparticles results from porous structures that are very similar to layers of Chalk River unidentified deposit formed on nuclear fuel rod surfaces during the reactor operation period. Although previous studies have investigated the surface effects through surface modifications, most studies are limited to pool boiling conditions, and therefore, the effects of porous surfaces on flow boiling heat transfer are still unclear. In addition, there have been only few reports on suppression of wetting for decoupled approaches of reasoning. In this study, bare and Al2O3 nanoparticle-coated surfaces were prepared for the study experiments. The CHF of each surface was measured with different mass fluxes of 1,600 kg/m(2)s, 1,800 kg/m(2)s, 2,100 kg/m(2)s, 2,400 kg/m(2)s, and 2,600 kg/m(2)s. The nanoparticle-coated tube showed CHF enhancement up to 17% at a mass flux of 2,400 kg/m(2)s compared with the bare tube. The factors for CHF enhancement are related to the enhanced rewetting process derived from capillary action through porous structures built-up by nanoparticles while suppressing relative wettability effects between two sample surfaces as a highly wettable R-123 refrigerant was used as a working fluid. Copyright (C) 2015, Published by Elsevier Korea LLC on behalf of Korean Nuclear Societyclose0

    Beam-beam simulation code BBSIM for particle accelerators

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    A highly efficient, fully parallelized, six-dimensional tracking model for simulating interactions of colliding hadron beams in high energy ring colliders and simulating schemes for mitigating their effects is described. The model uses the weak-strong approximation for calculating the head-on interactions when the test beam has lower intensity than the other beam, a look-up table for the efficient calculation of long-range beam-beam forces, and a self-consistent Poisson solver when both beams have comparable intensities. A performance test of the model in a parallel environment is presented. The code is used to calculate beam emittance and beam loss in the Tevatron at Fermilab and compared with measurements. We also present results from the studies of two schemes proposed to compensate the beam-beam interactions: a) the compensation of long-range interactions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at CERN with a current-carrying wire, b) the use of a low energy electron beam to compensate the head-on interactions in RHIC

    Signatures of unconventional pairing in near-vortex electronic structure of LiFeAs

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    A major question in Fe-based superconductors remains the structure of the pairing, in particular whether it is of unconventional nature. The electronic structure near vortices can serve as a platform for phase-sensitive measurements to answer this question. By solving Bogoliubov-de Gennes equations for LiFeAs, we calculate the energy-dependent local electronic structure near a vortex for different nodeless gap-structure possibilities. At low energies, the local density of states (LDOS) around a vortex is determined by the normal-state electronic structure. However, at energies closer to the gap value, the LDOS can distinguish an anisotropic from a conventional isotropic s-wave gap. We show within our self-consistent calculation that in addition, the local gap profile differs between a conventional and an unconventional pairing. We explain this through admixing of a secondary order parameter within Ginzburg-Landau theory. In-field scanning tunneling spectroscopy near vortices can therefore be used as a real-space probe of the gap structure
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