Observation of two-dimensional lattice interface solitons

We report on the experimental observation of two-dimensional solitons at the interface between square and hexagonal waveguide arrays. In addition to the different symmetry of the lattices, the influence of a varying refractive index modulation depth is investigated. Such variation strongly affects the properties of surface solitons residing at different sides of the interface.Comment: 14 pages, 5 figures, to appear in Optics Letter

Underwater Sound Characteristics of a Ship with Controllable Pitch Propeller

The time-dependent spectral characteristics of underwater sound radiated by an oceanic vessel have complex dependencies on ship machinery, propeller dynamics, and the hydrodynamics of the ship exhaust and motion, as well as onboard activities. Here, the underwater sound radiated by a ship equipped with a controllable pitch propeller (CPP) is analyzed and quantified via its (i) power spectral density for signal energetics, (ii) temporal coherence for machinery tonal sound, and (iii) spectral coherence for propeller amplitude-modulated cavitation noise. Frequency-modulated (FM) tonal signals are also characterized in terms of their frequency variations. These characteristics are compared for different propeller pitch ratios, ranging from 20% to 82% at a fixed number of propeller revolutions per minute (RPM). The efficacy and robustness of ship parameter estimation at different pitches are discussed. Finally, an analysis of one special measurement is provided: propeller pitch and RPM over the duration of the measurement when the ship changes speed. The 50% pitch was found to be a crucial point for this ship, around which the tonal characteristics of its underwater radiated sound attain their peak values while broadband sound and associated spectral coherences are at a minimum. The findings here elucidate the effects of pitch variation on underwater sound radiated by ships with controllable pitch propellers and has applications in ship design and underwater noise mitigation

Rigid Structure Response Analysis to Seismic and Blast Induced Ground Motions

AbstractComprehensive studies of rigid structure responses to seismic ground excitations have been reported. It was found that the rocking and sliding response of a rigid structure is highly nonlinear. The structure stability depends on the structure slenderness, as well as the ground motion amplitude, frequency and duration. Compared to an earthquake ground motion, ground shock induced by underground or surface explosion has very large amplitude, high frequency and short duration. Moreover, vertical component of a ground shock may be substantially larger than the gravitational acceleration g. This will cause the unanchored rigid structure jump or fly into air. Therefore, the responses and stability regions of a rigid structure to blast induced ground shock will be very different from those under seismic ground motions. No study of rigid structure response to ground shock of amplitude more than 1.0g can be found in the literature. As there might be many rigid structures such as computers, document shelfs, and other important equipments in a building or a military command center close to an explosion center, understanding rigid structure response to ground shock is essential for protection of such equipments. In this study, theoretical derivation and numerical prediction of rigid structure response to ground shock are carried out. Numerical results of stability regions of rigid structures to ground shock are derived. Particular attentions are paid to the case when the vertical ground shock is more than 1.0g and the rigid structure flies into the air. Results are compared to those obtained with earthquake ground motions. Discussions on the rigid structure stability to earthquake motion and ground shock are made

EP-1307: Innovative QA methodology for true patient-specific Dose Volume Histograms (DVHs) measurements

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Relayed-QKD and switched-QKD networks performance comparison considering physical layer QKD limitations

We experimentally evaluate the SKR generation for unoptimized QKD pairs in switched QKD and compare the performance of the switched-QKD with relayed-QKD networks to reveal they perform better for short distances and at large networks.Comment: 3 page

Observation of surface solitons in chirped waveguide arrays

We report the observation of surface solitons in chirped semi-infinite waveguide arrays whose waveguides exhibit exponentially decreasing refractive indices. We show that the power threshold for surface wave formation decreases with an increase of the array chirp and that for sufficiently large chirp values linear surface modes are supported.Comment: 12 pages, 3 figures, to appear in Optics Letter

EUHASS: The European Haemophilia Safety Surveillance system

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