78,652 research outputs found

    Non-Gaussian statistical models of surface wave fields for remote sensing applications

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    Based on the complete Stokes wave model with the bias term and using a simple mapping approach and an iteration solution method, we established a formula for the joint probability density function of the surface slope elevation of a nonlinear random wave field. The formula requires three parameters to define the whole density function: the rms surface elevation and slope values and the significant slope. This model represents the dynamics of the wave in a more direct way than the Gram-Charlier approximation. Based on this new statistical model and laboratory experiments, formula and numerical values of EM bias and dynamics bias are derived. The results indicate that various biases should be considered seriously if accuracy of the altimeter measurement is required in centimeter range

    Hamiltonian formalism of the DNLS equation with nonvanished boundary value

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    Hamiltonian formalism of the DNLS equation with nonvanishing boundary value is developed by the standard procedure.Comment: 11 page

    Studies related to ocean dynamics. Task 3.2: Aircraft Field Test Program to investigate the ability of remote sensing methods to measure current/wind-wave interactions

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    The feasibility of remote sensing of current flows in the ocean and the remote sensing of ocean currents by backscattering cross section techniques was studied. It was established that for capillary waves, small scale currents could be accurately measured through observation of wave kinematics. Drastic modifications of waves by changing currents were noted. The development of new methods for the measurement of capillary waves are discussed. Improvement methods to resolve data processing problems are suggested

    Neutrino Breakup of A=3 Nuclei in Supernovae

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    We extend the virial equation of state to include 3H and 3He nuclei, and predict significant mass-three fractions near the neutrinosphere in supernovae. While alpha particles are often more abundant, we demonstrate that energy transfer cross-sections for muon and tau neutrinos at low densities are dominated by breakup of the loosely-bound 3H and 3He nuclei. The virial coefficients involving A=3 nuclei are calculated directly from the corresponding nucleon-3H and nucleon-3He scattering phase shifts. For the neutral-current inelastic cross-sections and the energy transfer cross sections, we perform ab-initio calculations based on microscopic two- and three-nucleon interactions and meson-exchange currents.Comment: 6 pages, 2 figures, minor additions, to appear in Phys. Rev.

    Strategies for protecting intellectual property when using CUDA applications on graphics processing units

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    Recent advances in the massively parallel computational abilities of graphical processing units (GPUs) have increased their use for general purpose computation, as companies look to take advantage of big data processing techniques. This has given rise to the potential for malicious software targeting GPUs, which is of interest to forensic investigators examining the operation of software. The ability to carry out reverse-engineering of software is of great importance within the security and forensics elds, particularly when investigating malicious software or carrying out forensic analysis following a successful security breach. Due to the complexity of the Nvidia CUDA (Compute Uni ed Device Architecture) framework, it is not clear how best to approach the reverse engineering of a piece of CUDA software. We carry out a review of the di erent binary output formats which may be encountered from the CUDA compiler, and their implications on reverse engineering. We then demonstrate the process of carrying out disassembly of an example CUDA application, to establish the various techniques available to forensic investigators carrying out black-box disassembly and reverse engineering of CUDA binaries. We show that the Nvidia compiler, using default settings, leaks useful information. Finally, we demonstrate techniques to better protect intellectual property in CUDA algorithm implementations from reverse engineering

    Hamiltonian formalism of the Landau-Lifschitz equation for a spin chain with full anisotropy

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    The Hamiltonian formalism of the Landau-Lifschitz equation for a spin chain with full anisotropy is formulated completely, which constructs a stable base for further investigations.Comment: 11page

    Heliospheric plasma sheets

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    [1] As a high-beta feature on scales of hours or less, the heliospheric plasma sheet (HPS) encasing the heliospheric current sheet shows a high degree of variability. A study of 52 sector boundaries identified in electron pitch angle spectrograms in Wind data from 1995 reveals that only half concur with both high-beta plasma and current sheets, as required for an HPS. The remaining half lack either a plasma sheet or current sheet or both. A complementary study of 37 high-beta events reveals that only 5 contain sector boundaries while nearly all (34) contain local magnetic field reversals, however brief. We conclude that high-beta plasma sheets surround current sheets but that most of these current sheets are associated with fields turned back on themselves. The findings are consistent with the hypothesis that high-beta plasma sheets, both at and away from sector boundaries, are the heliospheric counterparts of the small coronal transients observed at the tips of helmet streamers, in which case the proposed mechanism for their release, interchange reconnection, could be responsible for the field inversions

    Consistency relation for the Lorentz invariant single-field inflation

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    In this paper we compute the sizes of equilateral and orthogonal shape bispectrum for the general Lorentz invariant single-field inflation. The stability of field theory implies a non-negative square of sound speed which leads to a consistency relation between the sizes of orthogonal and equilateral shape bispectrum, namely fNLorth.≲−0.054fNLequil.f_{NL}^{orth.}\lesssim -0.054 f_{NL}^{equil.}. In particular, for the single-field Dirac-Born-Infeld (DBI) inflation, the consistency relation becomes fNLorth.≃0.070fNLequil.≲0f_{NL}^{orth.}\simeq 0.070 f_{NL}^{equil.}\lesssim 0. These consistency relations are also valid in the mixed scenario where the quantum fluctuations of some other light scalar fields contribute to a part of total curvature perturbation on the super-horizon scale and may generate a local form bispectrum. A distinguishing prediction of the mixed scenario is τNLloc.>(65fNLloc.)2\tau_{NL}^{loc.}>({6\over 5}f_{NL}^{loc.})^2. Comparing these consistency relations to WMAP 7yr data, there is still a big room for the Lorentz invariant inflation, but DBI inflation has been disfavored at more than 68% CL.Comment: 4 pages, 2 figures; v2: title changed, some mistakes corrected; v3: refs added, version accepted for publication in JCA
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