83,489 research outputs found

    Soil analyses and evaluations at the impact dynamics research facility for two full-scale aircraft crash tests

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    The aircraft structural crash behavior and occupant survivability for aircraft crashes on a soil surface was studied. The results of placement, compaction, and maintenance of two soil test beds are presented. The crators formed by the aircraft after each test are described

    Laboratory requirements for in-situ and remote sensing of suspended material

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    Recommendations for laboratory and in-situ measurements required for remote sensing of suspended material are presented. This study investigates the properties of the suspended materials, factors influencing the upwelling radiance, and the various types of remote sensing techniques. Calibration and correlation procedures are given to obtain the accuracy necessary to quantify the suspended materials by remote sensing. In addition, the report presents a survey of the national need for sediment data, the agencies that deal with and require the data of suspended sediment, and a summary of some recent findings of sediment measurements

    Lattice QCD and Hydro/Cascade Model of Heavy Ion Collisions

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    We report here on a recent lattice study of the QCD transition region at finite temperature and zero chemical potential using domain wall fermions (DWF). We also present a parameterization of the QCD equation of state obtained from lattice QCD that is suitable for use in hydrodynamics studies of heavy ion collisions. Finally, we show preliminary results from a multi-stage hydrodynamics/hadron cascade model of a heavy ion collision, in an attempt to understand how well the experimental data (e.g. particle spectra, elliptic flow, and HBT radii) can constrain the inputs (e.g. initial temperature, freezeout temperature, shear viscosity, equation of state) of the theoretical model.Comment: 10 pages, 12 figures. Proceedings for the 26th Winter Workshop on Nuclear Dynamics, Ocho Rios, Jamaica, Jan 2-9, 201

    Laboratory requirements for in-situ and remote sensing of suspended material

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    Recommendations for laboratory and in-situ measurements required for remote sensing of suspended material are presented. This study investigates the properties of the suspended materials, factors influencing the upwelling radiance, and the various types of remote sensing techniques. Calibration and correlation procedures are given to obtain the accuracy necessary to quantify the suspended materials by remote sensing. In addition, the report presents a survey of the national need for sediment data, the agencies that deal with and require the data of suspended sediment, and a summary of some recent findings of sediment measurements

    A design study for an optimal non-linear receiver/demodulator Final report

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    Design study for optimal nonlinear receiver demodulato

    Analysis of B-> \phi K Decays in QCD Factorization

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    We analyze the decay BϕKB\to \phi K within the framework of QCD-improved factorization. We found that although the twist-3 kaon distribution amplitude dominates the spectator interactions, it will suppress the decay rates slightly. The weak annihilation diagrams induced by (SP)(S+P)(S-P)(S+P) penguin operators, which are formally power-suppressed by order (Λ/mb)2(\Lambda/m_b)^2, are chirally and logarithmically enhanced. Therefore, these annihilation contributions are not subject to helicity suppression and can be sizable. The predicted branching ratio of BϕKB^-\to\phi K^- is (3.8±0.6)×106(3.8\pm0.6)\times 10^{-6} in the absence of annihilation contributions and it becomes (4.31.4+3.0)×106(4.3^{+3.0}_{-1.4})\times 10^{-6} when annihilation effects are taken into account. The prediction is consistent with CLEO and BaBar data but smaller than the BELLE result.Comment: 13 pages, 3 figures. A major change for the presentation of branching-ratio predictions. Experimental data are update

    Non-linear vortex dynamics and transient effects in ferromagnetic disks

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    We report a time resolved imaging and micromagnetic simulation study of the relaxation dynamics of a magnetic vortex in the non-linear regime. We use time-resolved photoemission electron microscopy and micromagnetic calculations to examine the emergence of non-linear vortex dynamics in patterned Ni80Fe20 disks in the limit of long field pulses. We show for core shifts beyond ~20-25% of the disk radius, the initial motion is characterized by distortions of the vortex, a transient cross-tie wall state, and instabilities in the core polarization that influence the core trajectories.Comment: 11 pages, 3 figures, submitted to Phys. Rev. Let

    Phase soliton and pairing symmetry of a two-band superconductor: Role of the proximity effect

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    We suggest a mechanism which promotes the existence of a phase soliton -- topological defect formed in the relative phase of superconducting gaps of a two-band superconductor with s+- type of pairing. This mechanism exploits the proximity effect with a conventional s-wave superconductor which favors the alignment of the phases of the two-band superconductor which, in the case of s+- pairing, are pi-shifted in the absence of proximity. In the case of a strong proximity such effect can be used to reduce soliton's energy below the energy of a soliton-free state thus making the soliton thermodynamically stable. Based on this observation we consider an experimental setup, applicable both for stable and metastable solitons, which can be used to distinguish between s+- and s++ types of pairing in the iron-based multiband superconductors.Comment: New references, added discussion about self-consistency of the GL description of a phase soliton in the presence of a proximity patc
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