Z. Wang

We present a monolithic silicon photonic integrated circuit coherent modulator and receiver that works from 1260 to 1630 nm. We demonstrate 200-Gb/s unamplified 16-QAM transmission and long-range optical coherence tomography.

We present results from new optical and UV spectroscopy of the unusual binary system SS 433, and we discuss the relationship of the particular spectral components that we observe to the properties of the binary. These spectral components include

We present three-dimensional direct numerical simulation (DNS) results of a horizontal flexible pipe conveying two-phase incompressible flow at moderate Reynolds numbers (400 ∼ 700). We find that the Reynolds number (Re) and the void fraction (α) essentially determine the onset of self-sustained oscillations in the two-fluid/pipe system. We employ a phase-field formulation to solve the Navier-Stokes coupled with the Cahn-Hilliard equation and the structure equation in an arbitrary Lagrangian Eulerian (ALE) framework. A spectral/hp element method is adopted for the fluid solver and a Galerkin method for the structure solver. We construct stability diagrams showing the transitions between different states of the two-fluid/pipe system. Specifically, we focus on the transition from a stable state to a planar oscillatory state and also to an out-of-plane oscillatory state as a function of four non-dimensional parameters, the Reynolds number Re, the void fraction α, the fluid-tension parameter Ip, and the averaged flow velocity U. By comparing simulation results with those for a pipe conveying single-phase flow under similar conditions, we find that the two-fluid/pipe system loses stability at a lower Reynolds number. We also find that, under similar Re, Ip, and U, at values of void fraction α∈0.6∼0.8, corresponding to the slug/churn flow regimes, the pipe experiences the largest vibrations, which is consistent with previous experimental and theoretical studies. We also perform a spectral analysis and identify the different excited modes, which are found to vary depending on the values of the void fraction α.

Three-dimensional simulations of hydrodynamic jets are computed at rather high resolution using the ZEUS-3D code. The parameters we employ are suitable for moderate-to-high-power radio jets emerging through a galactic atmosphere or halo and eventually crossing a tilted pressure-matched interface with a hotter intracluster medium. Before they cross this interface, these simulations aim the jets so that they hit massive clouds within the galactic halo, with densities 10 or more times higher than the ambient atmospheric density and hundreds to thousands times the jet density. Such clouds are set up with radii several times that of the jet and could correspond to giant molecular cloud complexes or small cannibalized galaxies. We find that while powerful jets eventually disperse the clouds, for off-center collisions, nonaxisymmetric instabilities are induced in those jets. Those instabilities grow faster for lower Mach number jets and can disrupt the jets substantially sooner than occurs for similar simulations of jets not hitting clouds. Such interactions could be related to some compact steep-spectrum source morphologies. Weak jets can be effectively halted or destroyed by reasonably massive clouds, and this type of interaction may have relevance for the paucity of extended radio jets in spiral galaxies. Slow, dense jets may be bent yet remain stable for fairly extended times, and such interactions can be responsible for some of the wide-angle tail and most of the "dogleg" radio source morphologies.

Modern design processes such as set-based design and TIES (Technology Identification, Evaluation and Selection) depend on the ability to explore a large design space rather than attempting to optimize a single design. In this paper, we investigate methods for expanding the design space that can be explored using the S3D (Smart Ship System Design) software environment. We then detail the most recent advancements in the templating process, with the goal of automated system assembly and evaluation using pre-designed system segments called templates.