First principles numerical model of avalanche-induced arc discharges in electron-irradiated dielectrics

The model consists of four phases: single electron dynamics, single electron avalanche, negative streamer development, and tree formation. Numerical algorithms and computer code implementations are presented for the first three phases. An approach to developing a code description of fourth phase is discussed. Numerical results are presented for a crude material model of Teflon

Effect of dynamic stall on the aerodynamics of vertical-axis wind turbines

Accurate simulations of the aerodynamic performance of vertical-axis wind turbines pose a significant challenge for computational fluid dynamics methods. The aerodynamic interaction between the blades of the rotor and the wake that is produced by the blades requires a high-fidelity representation of the convection of vorticity within the wake. In addition, the cyclic motion of the blades induces large variations in the angle of attack on the blades that can manifest as dynamic stall. The present paper describes the application of a numerical model that is based on the vorticity transport formulation of the Navier–Stokes equations, to the prediction of the aerodynamics of a verticalaxis wind turbine that consists of three curved rotor blades that are twisted helically around the rotational axis of the rotor. The predicted variation of the power coefficient with tip speed ratio compares very favorably with experimental measurements. It is demonstrated that helical blade twist reduces the oscillation of the power coefficient that is an inherent feature of turbines with non-twisted blade configurations

Values and aspirations for coastal waters of the Kimberley: social values and participatory mapping using interviews. Technical Report. Kimberley Marine Research Program Node of the Western Australian Marine Science Institution

This is the first report from the “Values and aspirations for coastal waters of the Kimberley” research project funded by the Western Australian Government and administered by the Western Australian Marine Science Institution (Kimberley Research Node Project 2.1.2). The study area extends from the south western end of Eighty Mile Beach to the Northern Territory Border, a coastline 13,296 km in length at low water mark including the islands. The aim of this 3-year research project is to document and analyse the social values and aspirations of people associated with the existing and proposed marine parks at Eighty Mile Beach, Roebuck Bay, Lalang-garram (Camden Sound) and North Kimberley, and with other coastal waters of the Kimberley

Human values and aspirations for coastal waters of the Kimberley: Social values and management preferences using Public Participation GIS. Technical Report

This is the second technical report produced from the Western Australian Marine Science Institution Kimberley Research Node Project 2.1.2 Values and aspirations for coastal waters of the Kimberley. The study area encompasses all State coastal waters extending from the south western end of Eighty Mile Beach to the Northern Territory Border (Simpson 2011). A primary focus of the funding for this research, by the Western Australian Government, is to support the management of the proposed marine parks at Eighty Mile Beach, Roebuck Bay, Lalang-garram (Camden Sound), Horizontal Falls and North Kimberley (Figure 1). This research also encompasses the surrounding marine environment which includes Commonwealth marine parks as well as non-marine park waters

Features of a Separating Turbulent Boundary Layer as Revealed by Laser and Hot-Film Anemometry

Experiments have been performed to determine the fundamental nature of boundary layer separation produced by an adverse pressure gradient. Measurements upstream and downstream of the separation zone have been made utilizing laser and hot-film anemometry techniques. A completely mobile backscattering laser anemometer was developed. This alone is a significant development because of the relatively long focal lengths required for measurements in a 36 wide wind tunnel. Signal processing was achieved by a digital signal sampling and storage system. Both mean and fluctuating velocities in both the unseparated and separated flow regions were measured. Experimental results are in fairly good agreement with hot-film measurements, with some recent improvements in data acquisition being noted. Flush-wall hot-film sensors were used to determine wall shear stresses and fluctuations, both upstream and downstream of separation. These data indicate that the law of the wall apparently is valid up to the location of intermittent separation or the location of intermittent backflow next to the wall. Visual observations indicate that the location of intermittent separation is in agreement with Sandborn\u27s criterion. The outer region flow downstream of the beginning of separation is characterized by a similarity mixing-layer velocity profile

Ferromagnetic redshift of the optical gap in GdN

We report measurements of the optical gap in a GdN film at temperatures from 300 to 6K, covering both the paramagnetic and ferromagnetic phases. The gap is 1.31eV in the paramagnetic phase and red-shifts to 0.9eV in the spin-split bands below the Curie temperature. The paramagnetic gap is larger than was suggested by very early experiments, and has permitted us to refine a (LSDA+U)-computed band structure. The band structure was computed in the full translation symmetry of the ferromagnetic ground state, assigning the paramagnetic-state gap as the average of the majority- and minority-spin gaps in the ferromagnetic state. That procedure has been further tested by a band structure in a 32-atom supercell with randomly-oriented spins. After fitting only the paramagnetic gap the refined band structure then reproduces our measured gaps in both phases by direct transitions at the X point.Comment: 5 pages, 4 figure

Effect of crumb rubber on mechanical properties of multi-phase syntactic foams

Syntactic foam is a lightweight and strong material which can be used in marine and aeronautical applications. However, the brittleness of the material limits its application to a broader range. Adding crumb rubber to the syntactic foam can increase its energy absorption capacity. The effect of crumb rubber on the fracture toughness and energy absorption capacity of 2-phase and 3-phase syntactic foam is evaluated under both static and impact loads. The experimental results have shown that the fracture toughness of the 2-phase rubberized syntactic foam increased by 8% while an increase of 22% of its fracture energy was observed. Under quasi-static loads, the 3-phase rubberized syntactic foam showed decreases in the compressive strength and elastic modulus but an increase in the energy absorption capacity as compared to the syntactic foam without crumb rubber. In addition, the impact energy absorption of the 3-phase rubberized syntactic foam increased by 24% as compared to that of the 3-phase syntactic foam without crumb rubber

Painless Obstructive Jaundice Secondary to a Common Bile Duct Abscess: A Delayed Sequela of Cholecystectomy

Complications related to cholecystectomy are well described. Most occur in the early postoperative period and are recognised either at the time of, or shortly after surgery. Clinical sequelae occurring years following cholecystectomy are rare and infrequently reported. In addition, most delayed complications are related to the continuing presence or new formation of gallstones. In this paper we present a unique case of an abscess of the common bile duct wall, presenting with painless obstructive jaundice more than 30 years following an open cholecystectomy, without the presence of gallstones. The clinical presentation, investigations, and treatment are discussed with a review of other relevant reported cases in the literature

Properties of Galactic Outflows: Measurements of the Feedback from Star Formation

Properties of starburst-driven outflows in dwarf galaxies are compared to those in more massive galaxies. Over a factor of roughly 10 in galactic rotation speed, supershells are shown to lift warm ionized gas out of the disk at rates up to several times the star formation rate. The amount of mass escaping the galactic potential, in contrast to the disk, does depend on the galactic mass. The temperature of the hottest extended \x emission shows little variation around $\sim 10^{6.7}$ K, and this gas has enough energy to escape from the galaxies with rotation speed less than approximately 130 km/s.Comment: 11 pages + 3 figues. Accepted for publication in the Astrophysical Journa