Developments in efficiency and stability of fluid film bearings using new designs and test techniques

Recently developed techniques in the measurement of fluid film bearing dynamic behaviour, including stiffness and damping, have highlighted some interesting observations on the performance of a range of bearings. These are outlined together with suggested strands of further research aimed at improving the efficiency, reliability and cost of operating plant and equipment

The potential use of new forms of adjustable hydrodynamic bearings in the intelligent monitoring and maintenance of machine accuracies

New forms of adjustable fluid film hydrodynamic bearings have shown great potential for suppressing vibrations and maintaining accuracy of location of rotational centres. First demonstrated on a simulated grinding wheel machine tool rotor and spindle system, the principal has also been applied to the support bearings in a large marine gearbox application. In both cases the bearing adjustment feature was used to maintain or displace in a pro-active manner the centre of rotation irrespective of loads and changes of load, and to suppress instabilities and vibrations provoked by running at low and zero loads. It is felt that these characteristics could be of significant benefit in a range of applications when coupled with appropriate intelligent systems for monitoring and control

A novel continuously adjustable hydrodynamic bearing

A novel form of adjustable fluid film bearing has been devised whereby the hydrodynamic conditions can be changed in a continuously controlled manner during operation. The principle can be applied to conventionally orientated journal bearings, i.e. a shaft rotating within a stationary bearing housing; to inverse orientations, i.e. a rotor on a stationary shaft; and to thrust bearings. A theoretical model and computerised solution technique were developed in which the fluid film profile, temperature, viscosity and pressure fields were simultaneously solved. Experiments were conducted on journal bearing versions for which recently developed measurement techniques demonstrated stable operation at zero eccentricity, and the ability to move the rotational centre whilst in operation. Performance characteristics predicted by the computer model have been demonstrated in practice. The novel bearing has shown significant improvements over conventional designs in tems of stiffness, damping, rotational accuracy, power losses and temperature rise

The Australian Labour Market in 2007

Both global and domestic economic growth remained robust in 2007 resulting in historically low unemployment and high labour force participation in Australia. However, these favourable labour force statistics were overshadowed for much of the year by a number of other issues such as the continuing drought, high oil and petrol prices and associated inflation and interest rate pressures, a November federal election, and the first full year of the operation of the Work Choices legislation. This article will address each of these issues by presenting an analysis of the macroeconomy and labour market, and reviewing the labour market implications of the Work Choices legislation in Australia.economic performance; industrial relations legislation; labour market; Work Choices

Modeling asteroid collisions and impact processes

As a complement to experimental and theoretical approaches, numerical modeling has become an important component to study asteroid collisions and impact processes. In the last decade, there have been significant advances in both computational resources and numerical methods. We discuss the present state-of-the-art numerical methods and material models used in "shock physics codes" to simulate impacts and collisions and give some examples of those codes. Finally, recent modeling studies are presented, focussing on the effects of various material properties and target structures on the outcome of a collision.Comment: Chapter to appear in the Space Science Series Book: Asteroids IV. Includes minor correction

Testing for Dependence in Non-Gaussian Time Series Data

This paper provides a general methodology for testing for dependence in time series data, with particular emphasis given to non-Gaussian data. A dynamic model is postulated for a continuous latent variable and the dynamic structure transferred to the non-Gaussian, possibly discrete, observations. Locally most powerful tests for various forms of dependence are derived, based on an approximate likelihood function. Invariance to the distribution adopted for the data, conditional on the latent process, is shown to hold in certain cases. The tests are applied to various financial data sets, and Monte Carlo experiments used to gauge their finite sample propertiesLatent variable model; locally most powerful tests; approximate likelihood; correlation tests; stochastic volatility tests

Mean-field density functional theory of ananoconfined classical, three-dimensional Heisenberg fluid. I. The role of molecularanchoring

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 144, 194704 (2016) and may be found at https://doi.org/10.1063/1.4949330.In this work, we employ classical density functional theory (DFT) to investigate for the first time equilibrium properties of a Heisenberg fluid confined to nanoscopic slit pores of variable width. Within DFT pair correlations are treated at modified mean-field level. We consider three types of walls: hard ones, where the fluid-wall potential becomes infinite upon molecular contact but vanishes otherwise, and hard walls with superimposed short-range attraction with and without explicit orientation dependence. To model the distance dependence of the attractions, we employ a Yukawa potential. The orientation dependence is realized through anchoring of molecules at the substrates, i.e., an energetic discrimination of specific molecular orientations. If the walls are hard or attractive without specific anchoring, the results are “quasi-bulk”-like in that they can be linked to a confinement-induced reduction of the bulk mean field. In these cases, the precise nature of the walls is completely irrelevant at coexistence. Only for specific anchoring nontrivial features arise, because then the fluid-wall interaction potential affects the orientation distribution function in a nontrivial way and thus appears explicitly in the Euler-Lagrange equations to be solved for minima of the grand potential of coexisting phases.DFG, 65143814, GRK 1524: Self-Assembled Soft-Matter Nanostructures at Interface