Software Development for Laser Engineered Net Shaping

Laser Engineered Net Shaping, also known as LENSTM, is an advanced manufacturing technique used to fabricate near-net shaped, fully dense metal components directly from computer solid models without the use oftraditional machining processes. The LENSTM process uses a high powered laser to create a molten pool into which powdered metal is injected and solidified. Like many SFF techniques, LENSTM parts are made through a layer additive process. In the current system, for any given layer, the laser is held stationary, while the part and its associated substrate is moved, allowing for the each layer's geometry to be formed. Individual layers are generated by tracing out the desired border, followed by filling in the remaining volume. Recent research into LENSTM has highlighted the sensitivity ofthe processes to multiple software controllable parameters such as substrate travel velocity, border representation, and fill patterns. This research is aimed at determining optimal border outlines and fill patterns for LENSTM and at developing the associated software necessary for automating the creation ofthe desired motion control.Mechanical Engineerin

Guidance and Control in a Josephson Charge Qubit

In this paper we propose a control strategy based on a classical guidance law and consider its use for an example system: a Josephson charge qubit. We demonstrate how the guidance law can be used to attain a desired qubit state using the standard qubit control fields.Comment: 9 pages, 5 figure

Seismic behaviour of reinforced concrete frames in Australia

Many intra-tectonic plate regions are considered to have low to moderate seismic risk. However, devastating earthquakes can occur in these regions and result in high consequences in terms of casualties and damage. This paper presents an experimental and analytical investigation to understand the seismic capacity of typically detailed Australian reinforced concrete (RC) frames. The experimental programme included a series of progressively increasing earthquake simulator tests, using base motion with design spectrum similar to that for firm soil sites in Australian design code. The analytical study consisted of inelastic time-history analyses of 3-, 5- and 12-storey RC frames with ground acceleration patterns based on artificially generated earthquake data for Boston region (on the east coast of the US). The main objectives of this research were (1) to investigate the behaviour of non-seismically designed RC frames under a 500 year return period (YRP) earthquake and (2) to determine the different magnitudes of earthquake (YRP) that are likely to cause excessive structural and nonstructural damage or collapse of gravity-load-designed (GLD) RC frames. The performance of the frames was analysed in relation to the drift limits, base shear, ductility and overstrength.J. Kashyap, M. Griffith & T. Ozbakkalogluhttp://www.aees.org.au/Proceedings/2008_Index.pd

ATPMN: accurate positions and flux densities at 5 and 8 GHz for 8,385 sources from the PMN survey

We present a source catalogue of 9,040 radio sources resulting from high-resolution observations of 8,385 PMN sources with the Australia Telescope Compact Array. The catalogue lists flux density and structural measurements at 4.8 and 8.6 GHz, derived from observations of all PMN sources in the declination range -87 deg < delta < -38.5 deg (exclusive of galactic latitudes |b| 70 mJy (50 mJy south of delta = -73 deg). We assess the quality of the data, which was gathered in 1992-1994, describe the population of catalogued sources, and compare it to samples from complementary catalogues. In particular we find 127 radio sources with probable association with gamma-ray sources observed by the orbiting Fermi Large Area Telescope.Comment: 20 pages, 21 figure

Measurement of Linear Stark Interference in 199Hg

We present measurements of Stark interference in the 6$^1S_0$ $\rightarrow$ 6$^3P_1$ transition in $^{199}$Hg, a process whereby a static electric field $E$ mixes magnetic dipole and electric quadrupole couplings into an electric dipole transition, leading to $E$-linear energy shifts similar to those produced by a permanent atomic electric dipole moment (EDM). The measured interference amplitude, $a_{SI}$ = $(a_{M1} + a_{E2})$ = (5.8 $\pm$ 1.5)$\times 10^{-9}$ (kV/cm)$^{-1}$, agrees with relativistic, many-body predictions and confirms that earlier central-field estimates are a factor of 10 too large. More importantly, this study validates the capability of the $^{199}$Hg EDM search apparatus to resolve non-trivial, controlled, and sub-nHz Larmor frequency shifts with EDM-like characteristics.Comment: 4 pages, 4 figures, 1 table; revised in response to reviewer comment