Naval Surface Warfare Center

About: Naval Surface Warfare Center is a facility organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Radar & Sonar. The organization has 2855 authors who have published 3697 publications receiving 83518 citations. The organization is also known as: NSWC.

Nonlinear Meissner effect in a high-temperature superconductor: Local versus nonlocal electrodynamics

Abstract: Measured intermodulation distortion (IMD) power at 1.5 GHz in a series of ${\text{YBa}}_{2}{\text{Y}}_{3}{\text{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ stripline resonators of varying strip widths is compared to the predictions of two qualitatively distinct theories of the nonlinear Meissner effect. The stripline resonators are patterned from a single wafer to ensure uniformity of the material properties. According to the first theory [T. Dahm and D. J. Scalapino, Phys. Rev. B 60, 13125 (1999)], the IMD power is dominated by contributions from the strip edges, while according to the second theory [D. Agassi and D. E. Oates, Phys. Rev. B 72, 014538 (2005)] it is dominated by contributions from the body of the strip. The parameter-free comparison of the measured data with the theoretical predictions clearly favors the latter theory. We conclude that the nonlinear component of the penetration depth must be treated with nonlocal electrodynamics. The origins of this outcome are discussed briefly in the framework of a Green's-function approach.

Use of a kinematic constraint in tracking constant speed, maneuvering targets

Abstract: The use of a kinematic constraint as a pseudomeasurement in the tracking of constant speed, maneuvering targets is considered. A novel formulation of the constraint equation is presented and the rationale for this formulation is discussed. The filter using the kinematic constraint as a pseudomeasurement is shown to be unbiased, and sufficient conditions for stochastic stability of the filter are given. Simulation results indicate that the use of the novel formulation of the kinematic constraint improves the tracking of constant speed, maneuvering targets. >

Superconductor superlattice model for small-angle grain boundaries in Y-Ba-Cu-O.

Abstract: The measured critical current ratios of small-angle Y-Ba-Cu-O grain boundaries fabricated by Dimos {ital et} {ital al}., are calculated from a superconducting superlattice model where the periodicity is given by the Read-Shockley formula. The layers` thicknesses are estimated from stress-field calculations of a periodic edge-dislocations array model. The measured critical current dependence on the misalignment angle and the temperature are reproduced with a single fitting parameter. This parameter is related to the stress field in proximity to an edge dislocation. The model`s validity and comparison with other attempts at the same data are discussed.