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A blind H i survey of the extragalactic sky behind the southern Milky Way has been conducted with the multibeam receiver on the 64 m Parkes radio telescope. The survey covers the Galactic longitude range and Galactic latitudes to an rms sensitivity of 6 mJy per beam per 27 km s ⁻¹ channel and yields 883 galaxies to a recessional velocity of 12,000 km s ⁻¹. The survey covers the sky within the H i Parkes All-Sky Survey (HIPASS) area to greater sensitivity, finding lower H i mass galaxies at all distances, and probing more completely the large-scale structures at and beyond the distance of the Great Attractor. Fifty-one percent of the H

The derivation of the Helmholtz theorem of vector decomposition of a three-vector field requires that the field satisfy certain convergence properties at spatial infinity. This paper investigates if time-dependent electromagnetic radiation wave fields of point sources, which are of long range, satisfy these requirements. It is found that the requirements are satisfied because the fields give rise to integrals over the radial distance r of integrands of the form sin( kr)/ r and cos( kr)/ r. These Dirichlet integrals converge at infinity as required.

X-ray photoelectron spectra of some planar CuS ₄ copper N,N-dialkyl dithiocarbamate compounds in the formal +2 and +3 oxidation states and the CuO ₄ complex carbonate, Na ₂[Cu(CO ₃) ₂], have been recorded. Cu(2p _3/2) binding energies for the copper(II) dithiocarbamate and carbonate compounds are similar although the `shakeup' satellite structure for the dithiocarbamate compounds is relatively less intense. The modified Auger parameter, α', for the two sets of compounds is also similar but c a. 1-2 eV lower than the value reported for the most Cu(II) compounds. The copper binding and kinetic energy parameters for the Cu(III) compounds have been found to correspond to values found for the Cu(II) compounds with, however, an absence of secondary satellite structure. Differences between the compounds in the two oxidation states are also found in the ligand sulphur 2p binding energies which are c a....

A vertical levitation electrostatic comb drive actuator was manufactured for the purpose of measuring piezoelectric coefficients in small-scale materials and devices. Previous modelling work on comb drive levitation has focussed on control of the levitation in standard poly-silicon devices in order to minimize effects on lateral modes of operation required for the accelerometer and gyroscope applications. The actuator developed in this study was manufactured using a 20 μm electroplated Ni process with a 25 μm trench created beneath the released structure through chemical wet etching. A finite element analysis using ZINC was used to model electrostatic potential around a cross section of one static and one movable electrode, from which the net levitation force per unit electrode was calculated. The model was first verified using the electrode geometry from previously studied systems, and then used to study the variation of force as a function of decreasing substrate...

We report the development of a pulsed inductive microwave magnetometer for measurements of ultra-fast magnetization dynamics of soft magnetic thin films. This paper details the instrument construction and the measurement procedure. We show experimentally that our instrument detects nanosecond and sub-nanosecond magnetization precession/relaxation processes, in real time, without the need for data averaging, interpolation or any other post-measurement data processing. This enhanced detection resolution has been achieved by careful design and optimization of the coplanar waveguide, which will be described in detail in this paper. Moreover, we show that, unlike other similar instruments, our apparatus is significantly simplified, reducing the cost as well as the measurement procedure.

A micro-electro-mechanical systems (MEMS) vertical levitation comb drive actuator has been created for the measurement of piezoelectric coefficients in thin/thick films or piezoelectrically active micro-scale components of other MEMS devices. The device exerts a dynamic force of 33 μN at an applied voltage of 100 V. The charge developed on the piezoelectric test device is measured using a charge sensitive pre-amplifier and lock-in technique, enabling measurements down to 1×10 ⁻⁵ pC. The system was tested with ten different piezoelectric samples with coefficients in the range 70–1375 pC N ⁻¹ and showed a good correlation ( r = 0.9997) to measurements performed with macroscopic applied stresses, and piezoelectric impedance resonance techniques. The measurement of the direct piezoelectric effect in micro- and nano-scale piezo-materials has been made possible using MEMS processing technology. This new application of a MEMS metrology device has been de...

Prolonged operation of piezoelectric ceramic devices under high dc electric fields promotes leakage currents between the electrodes. This paper investigates the effects of ceramic porosity, edge conduction and electrode materials and geometry in the development of low resistance conduction paths through the ceramic. Localized changes in the ceramic structure and corresponding microscopic breakdown sites are shown to be associated with leakage currents and breakdown processes resulting from prolonged operation in harsh environments. The role of barrier coatings in mitigating the effects of humidity is studied, and results are presented on improved performance using composite diamond-like carbon/polymer coatings. In contrast to the changes in the electrical properties of the ceramic, the measurements of the piezoelectric properties showed no significant effect of humidity.

Motivated by quaint woodcut depictions often found in many late 16th and 17th century ballistic manuals of cannonballs fired in air, a comparison of their shapes with those calculated for the classic case of a projectile moving in a linear resisting medium is made. In considering the asymmetrical nature of such trajectories, the initial launch angle resulting in the greatest forward horizontal skew of the trajectory is found and compared to the corresponding launch angle which maximizes the range of the projectile. Limiting behaviour in the shape of the trajectory in the strong damping limit is also considered and compared to peculiar straight-lined triangular trajectory woodcuts from the late 16th century.

We investigate the existence and the global causal structure of plane symmetric spacetimes with weak regularity when the matter consists of an irrotational perfect fluid with pressure equal to its mass-energy density. Our theory encompasses the class of W ^{1, 2} regular spacetimes whose metric coefficients have square-integrable first-order derivatives and whose curvature must be understood in the sense of distributions. We formulate the characteristic initial value problem with data posed on two null hypersurfaces intersecting along a two-plane. Relying on Newman–Penrose's formalism and expressing our weak regularity conditions in terms of the Newman–Penrose scalars, we arrive at a fully geometrical formulation in which, along each initial hypersurface, two scalar fields describing the incoming radiation must be prescribed in L ¹ and W ^{−1, 2}, respectively. To analyze the future boundary of such a spacetime and identify its global ...

We show that a remark made by Hernández-Saldaña in 2010 ( Eur. J. Phys. 31 1319) concerning the validity of an expression first presented by us in 2006 ( Proc. 17th Biennial Congress of the Australian Institute of Physics Paper 27) for the optimal angle of projection for greatest forward skew in the trajectory of a projectile launched in a linear resisting medium is in error. We also draw attention to an earlier treatment (2006 Int. J. Math. Educ. Sci. Technol. 37 411) of the locus of apexes for such a projectile. When expressed in Cartesian form, the locus can be written in terms of the now familiar, though less common, secondary real branch of the Lambert W function.