Shear strength, consolidation and drainage of colliery tailing lagoons

Colliery tailings are laminated sediments which vary from coal-rich horizons of coarse sand size, to fine silt horizons composed mainly of quartz, illite and kaolinite. The proportion of finer laminae increases away from the inlet of the containing lagoon, although both fine and coarse bands are found everywhere in the lagoon. Coal itself has a low specific gravity and high friction coefficient. The density increases and the shear strength decreases away from the inlet. Both the average coal content (47%) and friction angle (35º) are higher for tailings than for coarse colliery discard (14% and 31º respectively). The permeability of the contrasting laminae differs greatly, and consolidation and drainage in lagoons is therefore dominated by the horizontally laminated structure. Much of the water in lagoons drains laterally to the embankments. This water contains dissolved solids which reflect the groundwater chemistry of the Coal Measures at depth, being both saline and rich in sulphates. Overtipping lagoons with coarse discard is being used increasingly for waste disposal purposes. It is possible to overtip with a 1.5m high layer of discard using a D6 vehicle at a sediment shear strength of 3 KN/m(_2) . However, to include a safety margin, 4.5 KN/m(_2) should be the lower bound. An effective stress stability study of overtipping indicates that a desiccated surface is necessary; the operation cannot progress where supernatant water remains on the lagoon. In terms of liquefaction hazards, vehicle vibration levels are not high enough to be of concern. Similarly, measured ground vibrations produced by explosives did not liquefy a lagoon being overtipped. It is suggested that a 200-year return period earthquake will not cause problems in this respect

Glass ceramics from a South African pulverised fuel ash

Bibliography: pages 92-101.The generation of electricity by the combustion of pulverised coal produces large quantities of coal ash (PF A). The disposal of this ash lias become a matter of concern due to the unsightly and hazardous nature of the PF A, and it has been the subject of intense investigations into its suitability as a raw material. Many uses have been proposed for the PF A. When used as landfill or mining backfill, the attraction is the low cost of the material. Other uses, as in the concrete industry, use PF A because of the improvements in quality of the resultant product. PF A has been suggested as a raw material for the production of wear resistant materials. The PF A is composed in the main of SiO₂ and AI₂O₃, and is a suitable material for the production of alumino-silicate ceramic materials, which are known to be tough and wear resistant. To establish the suitability of PF A from the Lethabo Power Station as a raw material, a project to prepare glass ceramic materials from the PF A was started. The conversion of the PF A to a glass ceramic material is a complex process involving many stages, and the processing at each stage will affects the final properties of the material. It is not possible in a short project such as this to examine all the factors which exert some control on the process, and so a small subset of these parameters was selected for study, namely the effect of added oxides on the crystallisation behaviour. Glass items which crystallise on holding at high temperatures commonly do so by growth of crystals from the surface of the item. This results in a material that is mechanically weak, due to the highly oriented microstructure that results. Nucleating agents can be used to obviate this. By providing sites for crystal growth in the bulk of the sample, they induce the crystallisation of fine grained ceramics with good mechanical properties. This study examines the effect of TiO₂, P₂O₅, and a mixture of iron and chrome oxides on the crystallisation of the glass prepared using PF A. The effect of these oxides was evaluated by examination of the microstructure of the crystalline specimens, and the kinetics of crystallisation were analysed by fitting data obtained by isothermal crystallisation of the specimens to the Avrami equation. Finally, the mechanical properties of the materials were tested by solid particle erosion, and the materials ranked against a selection of other materials used for their wear resistance

A Method for Greatly Reduced Edge Effects and Crosstalk in CCT Magnets

Iron-free CCT magnet design offers many advantages, one being the excellent field quality and the absence of multipole components. However, edge effects are present, although they tend to integrate out over the length of the magnet. Many modern accelerator applications, however, require that these magnets are placed in an area of rapidly varying optics parameters, so magnets with greatly reduced edge effects have an advantage. We have designed such a magnet (a quadrupole) by adding multipole components of the opposite sign to the edge distortions of the magnet. A possible application could be the final focus magnets of the FCC-ee, where beam sizes at the entry and exit point of the magnets vary by large factors. We have then used this technique to effectively eliminate cross talk between adjacent final focus quadrupoles for the incoming and outgoing beams.Comment: Poster presented at MT25,25th International Conference on Magnet Technology, Amsterdam, August 27 - September 1, 201

Oocyte cryopreservation as an adjunct to the assisted reproductive technologies

The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included. See page 2 of PDF for this item.Keith L Harrison, Michelle T Lane, Jeremy C Osborn, Christine A Kirby, Regan Jeffrey, John H Esler and David Mollo

Quasi-planar steep water waves

A new description for highly nonlinear potential water waves is suggested, where weak 3D effects are included as small corrections to exact 2D equations written in conformal variables. Contrary to the traditional approach, a small parameter in this theory is not the surface slope, but it is the ratio of a typical wave length to a large transversal scale along the second horizontal coordinate. A first-order correction for the Hamiltonian functional is calculated, and the corresponding equations of motion are derived for steep water waves over an arbitrary inhomogeneous quasi-1D bottom profile.Comment: revtex4, 4 pages, no figure

A peer-to-peer infrastructure for resilient web services

This work is funded by GR/M78403 “Supporting Internet Computation in Arbitrary Geographical Locations” and GR/R51872 “Reflective Application Framework for Distributed Architectures”, and by Nuffield Grant URB/01597/G “Peer-to-Peer Infrastructure for Autonomic Storage Architectures”This paper describes an infrastructure for the deployment and use of Web Services that are resilient to the failure of the nodes that host those services. The infrastructure presents a single interface that provides mechanisms for users to publish services and to find hosted services. The infrastructure supports the autonomic deployment of services and the brokerage of hosts on which services may be deployed. Once deployed, services are autonomically managed in a number of aspects including load balancing, availability, failure detection and recovery, and lifetime management. Services are published and deployed with associated metadata describing the service type. This same metadata may be used subsequently by interested parties to discover services. The infrastructure uses peer-to-peer (P2P) overlay technologies to abstract over the underlying network to deploy and locate instances of those services. It takes advantage of the P2P network to replicate directory services used to locate service instances (for using a service), Service Hosts (for deployment of services) and Autonomic Managers which manage the deployed services. The P2P overlay network is itself constructed using novel Web Services-based middleware and a variation of the Chord P2P protocol, which is self-managing.Postprin