Aerodynamic stiffness of an unbound eccentric whirling centrifugal impeller with an infinite number of blades

An unbounded eccentric centrifugal impeller with an infinite number of log spiral blades undergoing synchronous whirling in an incompressible fluid is considered. The forces acting on it due to coriolis forces, centripetal forces, changes in linear momentum, changes in pressure due to rotating and changes in pressure due to changes in linear momentum are evaluated

Dynamic Characteristics and Stability Analysis of Space Shuttle Main Engine Oxygen Pump

The dynamic characteristics of the Space Shuttle high pressure oxygen pump are presented. Experimental data is presented to show the vibration spectrum and response under actual engine operation and also in spin pit testing for balancing. The oxygen pump appears to be operating near a second critical speed and is sensitive to self excited aerodynamic cross coupling forces in the turbine and pump. An analysis is presented to show the improvement in pump stability by the application of turbulent flow seals, preburner seals, and pump shaft cross sectional modifications

The Australian Movement against Uranium Mining: Its Rationale and Evolution

This paper begins with a brief historical overview of the Australian movement against uranium mining, before focussing on two major campaigns: Roxby and Jabiluka. It describes the reasons the activists gave at the time for their blockades of the Roxby Downs uranium mine in South Australia in 1983 and 1984. These reasons – such as perceptions that the industry is unsafe - have changed little over time and were the basis for the campaign against the proposed Jabiluka mine in the Northern Territory in 1998. They continue to be cited by environmental groups and Aboriginal Traditional Owners to this day as new situations arise, such as the 2011 Fukushima Daiichi nuclear accident.The paper then describes how the movement evolved between the Roxby and Jabiluka blockades, with changes to the movement’s philosophy, strategy, tactics and internal dynamics. This analysis includes a comparison between two anti-nuclear bike rides, one a year after the 1984 Roxby blockade and involving some of the same activists, and another at the time of the Jabiluka blockade. This author was present at all these events, and provides an emic (insider) perspective within a longitudinal participant-observation methodology. Although this perspective obviously has a subjective element, the paper fills a gap in that there is little written history of these blockades (particularly Roxby) and more generally of Australian resistance to uranium mining, let alone the aspects of nonviolence and movement evolution. It is an introductory history of these campaigns, examining the direct action components, the practicalities of nonviolent campaigning, and the evolution of Australian anti-uranium activism

Hydraulic forces on a centrifugal impeller undergoing synchronous whirl

High speed centrifugal rotating machinery with large vibrations caused by aerodynamic forces on impellers was examined. A method to calculate forces in a two dimensional orbiting impeller in an unbounded fluid with nonuniform entering flow was developed. A finite element model of the full impeller is employed to solve the inviscid flow equations. Five forces acting on the impeller are: Coriolis forces, centripetal forces, changes in linear momentum, changes in pressure due to rotation and pressure changes due to linear momentum. Both principal and cross coupled stiffness coefficients are calculated for the impeller

Are there prehistoric shell middens on Rottwest Island?

In August 1973 a number of different types of shell bed were observed at Rottnest Island. The most massive of these were seen around the lakes at the eastern end of the island and there is no doubt that these are natural marine shell beds. However elsewhere shelly deposits were seen whose origin we could not determine with certainty. A number of midden like lenses of shell were exposed in road sections, particularly along the north side of the island. All of these deposits displayed some of the characteristics of Aboriginal shell middens

Editorial: Mining in a Sustainable World

Humanity has reaped great benefits from mining. Over the millennia that humans have practiced mining, there have been many obvious improvements in mining’s environmental and social impacts. However, some aspects of mining still involve an element of ecological violence and, in Australia, there is a growing amount of conflict concerned with mining. These two related issues – ‘ecological violence’ and ‘conflict’ – were explored at the ‘Mining in a Sustainable World’ conference on 13 to 15 October 2013 at the University of New England campus in Armidale, Australia. The conference was a joint initiative of the University of New England’s Peace Studies and Australian Centre for Agriculture and Law. Specifically, conference delegates were interested in exploring the work being done to reduce ecological violence and conflict. Articles in this special edition of the International Journal of Rural Law and Policy arose from that conference. This editorial provides an overview of the rationale for the conference and the issues explored.

Dependence of energy dissipation on annealing temperature of melt–spun NdFeB permanent magnet materials

A model of magnetic hysteresis which was developed originally for soft magnetic materials has been applied to melt–spun ribbons of Nd2Fe14B‐based material. The crucial ideas in the model description of hysteresis center on a dissipation of energy due to hysteresis which is proportional to the change in magnetization. The Nd2Fe14B material was melt–spun amorphous and then annealed for a period of 24 h at temperatures ranging from 700 to 950 °C. This resulted in different grain sizes, depending on annealing temperature. Consequently the hysteresis curves represent the properties of the material as a function of both annealing temperature and grain size. It was found that the magnetic properties varied systematically with annealing temperature, and hence grain size, as would be expected. When modeling the magnetic properties it was found that the model parameters also varied systematically, in particular, the energy dissipation parameter k was to a first approximation a simple linear function of the annealing temperature and decreased with increasing annealing temperature as a result of grain growth. Therefore, this study revealed a basic relationship between materials processing conditions, microstructure, model parameters, and magnetic properties