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Maximizing capacity of underground mine water chilling machines rejecting heat into a limited supply of water pumped to surfaceWright, Clifford Dale 26 July 2016 (has links)
A project report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering.
Johannesburg, 2016 / Underground chilling installations have an important role in deep mining operations because the total cost of cooling a mine is minimized when underground machines deliver as high a proportion of the required cooling as practicable. Thus the refrigerating load of an underground installation should be maximized to the extent permitted both by the environment in which the installation operates, and by the physical characteristics of the machines in the installation. This study analyses how, and to what extent, the refrigerating load of older, already installed water chilling machines rejecting heat into a limited supply of return water may be maximized through configuration of their water circuits and capacity control of their compressors. Multiple-machine installations are simulated in a range of scenarios, using the thermodynamically efficient series-counterflow arrangement, to predict both the potential maximum refrigerating load and the expected refrigerating load of such installations. The simulation results indicate significant potential for installations to chill water more efficiently and thus deliver larger, maximized, refrigerating loads. For scenarios where a larger-than-design flowrate of return water is available, so permitting machines to be operated with little or no capacity control, the simulated chilling efficiency and thus the expected refrigerating loads tend toward, and in some cases almost match, the potential maximum values. For simulations in which compressor capacity control is used to prevent the return water temperature from exceeding its maximum permitted value, expected refrigerating loads fall short of their potential values, by varying amounts, due to the low machine cycle efficiency caused largely by reduced compressor isentropic efficiency at part load. For a limited supply of return water for heat rejection, the simulations indicate that load maximization efforts should focus on the machines in an installation being connected in a series-counterflow arrangement and operated, as far as practicable, at or near full capacity to create the best prospect for approaching potential maximum refrigerating load.
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Evaluation and selection of commercially available recreation equipment for use by physically handicapped childrenPaul, Steven K January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
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Spear soil opener effects on soil physical properties & impact on wheat production / Rohan William Rainbow.Rainbow, Rohan William January 2000 (has links)
Includes bibliographical references (leaves 11-1-11-26). / xv, 222 leaves : ill. (some col.) : 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Adelaide University, Dept. of Agronomy and Farming Systems, 2001
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Implementation of radiation film dosimetry system to be used for the verification of a 3-D electron pencil-beam algorithm on a radiation treatment planning systemJones, Quyen L. 11 June 2004 (has links)
Radiation film dosimetry process using the RIT 113 v.4 dosimetry software and the
film digitizer VXR-l2plus was used to evaluate the accuracy of electron dose
calculations of the RAHD radiation therapy treatment planning system at Samaritan
Regional Cancer Center. Kodak Ready-Pack EDR-2 film is recommended for
dose distribution analysis in clinically practical dose ranges. The pencil-beam
algorithm has a limitation for calculating dose in the penumbra region and in the
tail region where the dose falls off. / Graduation date: 2005
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The quantitative evaluation of radiological workplace indicatorsBrock, Terry A. 05 September 2002 (has links)
Graduation date: 2003
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Multiple antenna wireless systems: capacity and user performance limitsAiry, Manish 28 August 2008 (has links)
Not available / text
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SIMULATED ANNEALING AND ESTIMATION THEORY IN CODED-APERTURE IMAGING (RECONSTRUCTION, MONTE CARLO, WIENER FILTER).SMITH, WARREN ESCHHOLZ. January 1985 (has links)
Coded-aperture imaging without detector motion can be used to reconstruct three-dimensional radionuclide distributions in the context of nuclear medicine. This approach offers several advantages over the rotating gamma-ray camera systems presently employed in the clinic. These advantages include improved sensitivity, potentially better spatial resolution, and the capability of doing dynamic studies. There are two problems associated with the coded-aperture approach, however. First, the data is "multiplexed", which refers to the fact that many line integrals of the source distribution are combined together and not measured individually, so that information is lost. Second, the number of resolvable detector elements is typically an order of magnitude less than the number of object elements to be reconstructed, so that the reconstruction problem is underdetermined. Consequently, the reconstruction is not unique. By using various types of a priori information in forming the reconstruction, however, it is possible to augment the incomplete data set. Two algorithms are presented to reconstruct objects from their coded-image projections and various types of a priori information. The first, a Monte Carlo algorithm, is a flexible and computationally efficient approach using the a priori knowledge of positivity and nearest-neighbor correlation. This algorithm is used to qualitatively explore the effect of the data-taking geometry on reconstruction performance. The second algorithm is a linear estimator incorporating as a priori knowledge completely general first- and second-order statistical information about the object class to be reconstructed. The linear-estimator formalism also provides a minimum-variance expression for system optimization. This linear algorithm is used to explore the effects of correct and incorrect a priori information on reconstruction performance, and to quantitatively investigate reconstruction quality with respect to data-taking geometry.
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Management of continuous system models in DEVS-SCHEME: Time windows for event-based controlWang, Qingsu, 1952- January 1989 (has links)
This thesis describes the design and implementation of an extended knowledge-based modeling and simulation environment, in which the management of continuous-time models in DEVS-SCHEME is realized to meet the requirements of the modeling and simulation of a robot-managed laboratory aboard the forthcoming Space Station Freedom. The modular hierarchical modeling scheme is preserved in the continuous models by using DYMOLA, a continuous modeling language, as a bridge between the abstracted DEVS models and the continuous simulation language code (in DESIRE). Through operations on the System Entity Structure (SES), a knowledge representation scheme, models at different granularity levels are generated. Time-windows can be obtained by manipulating a pruned SES. These time windows can be used to generate an equivalent discrete-event model at a coarser granularity. Therefore, an event-based intelligent control strategy can be realized in this knowledge-based multi-facetted modeling environment. Continuous-time and discrete-event modeling and simulation can be merged with AI techniques.
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Light conversion, S/N characteristics of x-ray phosphor screensLum, Byron Kwai Chinn January 1980 (has links)
No description available.
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Effects of fat levels and cage density on energy utilization by laying hensMadrid Lopez, Arturo January 1980 (has links)
No description available.
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