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Convex Hypersurfaces With Pinched Principal Curvatures And Flow Of Convex Hypersurfaces By High Powers Of Curvature, Ben Andrews, James Mccoy
Convex Hypersurfaces With Pinched Principal Curvatures And Flow Of Convex Hypersurfaces By High Powers Of Curvature, Ben Andrews, James Mccoy
Faculty of Informatics - Papers (Archive)
We consider convex hypersurfaces for which the ratio of principal curvatures at each point is bounded by a function of the maximum principal curvature with limit 1 at infinity. We prove that the ratio of circumradius to inradius is bounded by a function of the circumradius with limit 1 at zero. We apply this result to the motion of hypersurfaces by arbitrary speeds which are smooth homogeneous functions of the principal curvatures of degree greater than one. For smooth, strictly convex initial hypersurfaces with ratio of principal curvatures sufficiently close to one at each point, we prove that solutions remain …
Potential Reduction In Energy Use From A High Speed Rail Network In Australia, Philip Laird
Potential Reduction In Energy Use From A High Speed Rail Network In Australia, Philip Laird
Faculty of Informatics - Papers (Archive)
High Speed Rail or HSR with electric passenger trains using steel wheels on steel rails with maximum operating speeds of 250km/h or more is now operational in 12 countries. It is now under review in Australia. The paper considers energy use on the 10 top routes of the Melbourne-Sydney and Sydney-Brisbane corridors and finds that HSR was in place by 2020, HSR could reduce the use of aviation fuel by over 450 million litres each year. External costs and Sydney airport issues are also noted.
Factors Associated With Trends In Bare Ground In High Country, Heather North, Kenneth G. Russell
Factors Associated With Trends In Bare Ground In High Country, Heather North, Kenneth G. Russell
Faculty of Informatics - Papers (Archive)
Soil erosion in the Canterbury high country has been a concern for many years, and Environment Canterbury wishes to encourage land management practices that will preserve soil quality and vegetative cover. Environment Canterbury brought to MISG2005 a data set spanning three decades of bare ground monitoring in the Canterbury high country, along with data on factors with potential to impact on the processes of revegetation. These include topographic and climate data, soil nutrient status and land management factors. The study group analysed these data with the aim of determining whether trends in bare ground can be predicted from the potential …
Preliminary Design Of A High Tc Superconducting Persistent Mode Current Switch, Christopher J. Hawley, Dominic Cuiuri, Steve Gower
Preliminary Design Of A High Tc Superconducting Persistent Mode Current Switch, Christopher J. Hawley, Dominic Cuiuri, Steve Gower
Faculty of Informatics - Papers (Archive)
Persistent Mode Current Switches (PMCS) are made from coils of superconductor that in theory will provide zero conduction losses when closed. By causing a section of the superconductor to leave its superconducting state and become resistive, the switch is effectively opened. There are currently 3 methods to open a PMCS; 1) applying heat, 2) applying a magnetic field or 3) application of current above the critical current (Ic) of the tape. The first two methods are not suitable for power applications as the switching time is too slow. Recent work at the University of Wollongong and in literature has shown …
Modelling Of High Temperature Superconducting Wires And Coils, Christopher David Cook, T Hardono
Modelling Of High Temperature Superconducting Wires And Coils, Christopher David Cook, T Hardono
Faculty of Informatics - Papers (Archive)
This paper discusses modelling techniques for high temperature superconducting (HTSC) wires and coils. Models are developed based on the behaviour of Bi-2223/Ag wires and coils. For many power-engineering applications it is necessary to form HTSC wires into coils. PSpice models for HTSC coils will be presented in this paper. The aim is to develop models for HTSC wires and coils so that they can be treated as circuit elements in PSpice. The critical current of a coil will in general be different from the wire it is manufactured from and this change in current for a HTSC coil will be …
Characterisation Of High Temperature Superconducting Coils, Christopher David Cook, Sarath Perera, Thomas Hardjono
Characterisation Of High Temperature Superconducting Coils, Christopher David Cook, Sarath Perera, Thomas Hardjono
Faculty of Informatics - Papers (Archive)
Some power engineering systems, such as efficient energy storage for power quality improvement, can be potentially made more efficient if implemented with large coils made of high temperature superconductors (HTS). However, the losses of HTS coils carrying AC current limit their usage in practical applications. It has been shown previously that a thin pancake coil with relatively large diameter can be modelled as straight tapes arranged in a face-to-face stack. This paper reviews those results. In addition, measurements on a more realistic larger HTS coil were carried out. It is shown that the model assumptions provide less accurate results for …
Design Of A High Temperature Superconductor Magnetic Energy Storage Systems, R L Causley, Christopher David Cook, Steve Gower
Design Of A High Temperature Superconductor Magnetic Energy Storage Systems, R L Causley, Christopher David Cook, Steve Gower
Faculty of Informatics - Papers (Archive)
The University of Wollongong (UoW) has received funding for the research and development of a 20 kJ high temperature superconducting magnetic energy storage device (HTS SMES). This SMES will be operated at 25 K in contrast to most existing HTS designs, which operate at 77K. This paper includes a literature review of the current technology for the configuration of the SMES coil and a summary of the work done at UoW to date. Solenoidal and toroidal coils designs are compared to determine which will provide the required level of energy stored for a minimum superconductor and device volume. The design …
Behavioural Modelling Of High Temperature Superconducting Wires And Coils For Power Engineering Applications, Thomas Hardjono, Christopher David Cook, Sarath Perera
Behavioural Modelling Of High Temperature Superconducting Wires And Coils For Power Engineering Applications, Thomas Hardjono, Christopher David Cook, Sarath Perera
Faculty of Informatics - Papers (Archive)
Many aspects of the behaviour of high temperature superconducting (HTS) wires are well understood for dc applications. However, models of HTS suitable for use in circuit analysis by power engineers designing HTS applications are not readily available. This paper describes the initial development of suitable models for HTS wire. The V-I characteristics for wires carrying dc transport current can be empirically determined using a power law V=kIn. Experimentally measured V-I characteristics are fitted using the above power law. This enables the simulation of the behaviour of Bi-2223/Ag wire using the well-known circuit simulator PSpice. Other factors affecting the dc critical …