No description available.

No description available.

In rotating machinery there exist mechanical and electrical losses. With the advent of more efficient power-electronic devices, the shift has been towards reducing mechanical losses. There are solutions that exist, such as air bearings and oil-mist bearings that go some way to reducing these losses. In order to produce an even more efficient machine, windage losses must be reduced. This can be achieved by placing the machine in a vacuum. It becomes clear, therefore, that the bearing system can only be of the magnetic type. An area of research interest that has developed as a result of higher-efficiency machines is that of flywheel-energy storage systems. The most effective machine for flywheel energy storage is the permanent-magnet machine. This does not require external excitation for motoring or generating and is easier to operate as a generator than an induction machine. In this work a permanent-magnet synchronous machine is designed and constructed, with the aid of finite-element analysis. The rotor is a novel design which uses six magnets in a two-pole configuration. This gives a rotor which is mechanically and magnetically good, yet it does not require the use of a can. The testing of this machine shows a good correlation between predicted and measured results. When a permanent-magnerto tor is placed in bearingst hat allow it to move radially, there exists an unbalanced magnetic pull between rotor and stator. These forces are predicted using a finite-element method and then measured. These results are then used as a basis . for the design of an active magneticb earing The magneticb earingw as found to be able to 0 C7 cope with these forces. The magnetic bearing itself was used as a novel way of measuring the unbalanced magnetic forces, which required no contact between the rotor and the transducer.

Forensic crime laboratories receive hair shafts as evidentiary samples and process them for DNA evidence as a means of identification of individuals. The Armed Forces DNA Identification Laboratory (AFDIL) provides DNA analysis to aid in the medico-legal death investigation of fallen service members and contributes to research and education in the field of forensic DNA analysis. The AFDIL receives hair samples from family members of service individuals as a reference standard as well as remains from both past and present day conflicts for identification. Often times nuclear DNA is too highly degraded in hair shafts to be obtained successfully. There are many more copies of mitochondrial DNA in a cell than nuclear DNA. Therefore, it is common practice to target mitochondrial DNA instead of nuclear DNA when processing a hair shaft for DNA evidence. Mitochondrial DNA also plays an important role at the AFDIL in familial identification when a self-reference standard is not available. The current validated protocol for extracting mitochondrial DNA (mtDNA) at the AFDIL is a manual digestion with a micro-tissue grinder followed by a 24-hour incubation step and an organic phenol-chloroform extraction. The first part of this study compares the currently validated organic extraction method with the new QIAGEN QIAamp® Fast DNA Tissue Kit extraction method. The QIAamp® Fast DNA Tissue Kit extraction is a mechanical, chemical, and enzymatic protocol involving a 2 mL disruption tube with a stainless steel bead which aides in disruption of the hair followed by a silica-column based purification. The QIAamp® Fast DNA Tissue Kit is a single day protocol which reduced lab processing time by more than half (7 hours to 3 hours). When results from six different hair samples extracted with the current organic method were compared with the same samples extracted with the QIAamp® Fast DNA Tissue Kit method, it was found that the two methods are comparable for mtDNA recovery, amplification, and sequencing. Recently, researchers at InnoGenomics© (New Orleans, LA) have developed nuclear DNA quantification and amplification kits that target small DNA fragments, creating the potential to obtain sufficient nuclear DNA data from samples containing highly degraded DNA. Instead of targeting loci that contain short tandem repeats (STRs), the InnoQuant™ DNA quantification kit and InnoTyper 21™ DNA typing kit (InnoGenomics©, New Orleans, LA) targets retrotransposable elements (REs). The second part of this study compares nuclear DNA extraction methods from hair shafts such as the QIAamp® Fast DNA Tissue Kit, a direct lysis procedure using ZyGEM® prepGEM™ enzyme, and direct lysis procedures using pronase. Nuclear DNA extracts were quantified InnoQuant™ and InnoTyper 21™ for DNA typing. Full profiles were obtained using the InnoTyper 21™ amplification kit from samples with as low as 0.0331 ng of DNA which were extracted with 0.05 mg/mL. However, no single extraction method demonstrated consistently higher DNA concentrations or more complete DNA profiles.

No description available.

No description available.

In recent years a number of research centres have endeavoured to provide a mathematical model that indicates the chief characteristics of ore flow in the sublevel caving mining method. Optimization of the design parameters for sublevel caving has ensued with the objective of maximizing ore recovery while minimizing waste dilution. Past studies have been confined by two simplifying assumptions: that the region of flow be approximated by a simple mathematical function, and that the flow analysis is static, ie extraction is calculated by employing an idealized ore-waste boundary position for each ring. Further investigation into models of ore flow has been stimulated on two counts.1. full scale tests have indicated that a more complex description is required;2. as a design tool, a dynamic analysis that monitors the displacement of the broken rock mass during extraction would yield more realistic recovery predictions under operating conditions, and enable variations on the method to be evaluated.This study reviews the various formulations currently available, or being developed to describe the flow of granular material. A viable solution in a mining context would be three dimensional, time dependent, and incorporate stress conditions. Although workers in diverse fields have analyzed the problem no solution exists at present. The majority of studies are either empirical in nature, or deficient in one or other of the above criteria. Two approaches are developed and implemented on a digital computer:(i) stochastic flow model(ii) empirical flow model based on the results of modelling studies, and full scale test. Although a number of concepts introduced in these models remain to be verified, the validity of these models would be measured by their success or failure as a simulation tool in a mining environment.

Thesis (M.S.)--Ohio University, June, 1987. / Title from PDF t.p.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 1997. / Due to the extreme costs of establishing new shaft systems in Witwatersrand gold mines it is essential that the resource estimation is optimised, The result of poor Of sub-optimal estimation could be catastrophic even.to the largest of mining companies. This project examines the application of Compound Lognormal Distribution theory and shows the advantages of this distribution model over more traditional models, for the Carbon Leader Reef. The incorporation of information from mined out areas of a deposit in resource estimation is demonstrated. The critical role played by accurate geological modelling is highlighted. The process of Macro Co-Kriging in conjunction with Compound Lognormal Theory is discussed in detail and is shown to be a more accurate estimation technique than traditional techniques using Lognormal theory. Finally the use of the Macro Co-kriged limits are shown to be useful in the classification of Mineral Resources. / AC2017

No description available.