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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Performance of paste fill fences at Red Lake Mine

Hughes, Paul B. 05 1900 (has links)
Advancements in technology in mining have allowed previously unfeasible ore bodies to be developed. Paste backfill is one technological advancement that has allowed for the development of high-grade, low tonne production when employing the cut and fill mining method. Goldcorp Inc.'s Red Lake Mine currently utilizes this method and is the site for the study of this thesis. Paste backfill (paste) is defined as a mine backfill material that consists of eighty-five percent solids by weight and does not bleed water when placed often consisting of between two and fifteen percent Portland cement by weight. A paste barricade or paste fill fence is a constructed barricade whose purpose is to retain backfill within a mined out stope. The construction of the barricade varies with different operations, for Red Lake Mine the barricade consists of an anchored rebar skeleton covered with an adequate thickness of shotcrete. The majority of the applicable barricade research focuses on hydraulic fill barricades in open stope mining. The barricade pressures in these instances are much larger than those experienced in paste backfill barricades. As such, the current paste loading theory is based on material with a different loading mechanism. Although some research is currently underway, the majority of the barricade research is based on brick barricades and not the shotcrete, rebar skeleton as used at Red Lake. Catastrophic failures of barricades can occur without an understanding of the loading mechanisms. Based on the catastrophic risk, this thesis provides an investigation into the behaviour of the paste backfill and paste barricades at Red Lake Mine in order to provide a safe, cost effective design of paste barricades. This thesis develops an understanding of paste loading mechanisms and barricade capacity derived from a field study of nine instrumented fill fences at Red Lake Mine. Eight of thefences were instrumented to monitor the reaction strain in the fence and the applied pressures during standard production paste pours, the ninth fence was a controlled destructive test that determined the ultimate capacity of the fence. The data for these tests were gathered in real time and was subsequently reduced to assist in analysis. Yield Line Theory, Rankine Theory, strain induced stress, stress vs. strain analysis and numerical modeling were used to develop an understanding of the paste loading mechanisms and the capacity of the paste fill barricades. The analysis determined that the paste backfill behaves as a Rankine-like soil in the initial stages of loading with an average coefficient of lateral earth pressure, Ka, of 0.56. The destructive test determined that the yielding stress of a paste barricade is approximately 100 kPa. Further findings from the research determined that the rate of placement of paste does effect the loads applied to the fence and that the largest pressures exerted on the fill fence occur when paste lines were flushed with water at the end of the pour. This thesis provides an understanding of the paste loading and fill fence interaction with respect to failure. Based on this research the Red Lake Mine should be able to increase production without increasing risk to mine personnel by quantifying the overall loading and strengths of the fill barricade.
12

Performance of paste fill fences at Red Lake Mine

Hughes, Paul B. 05 1900 (has links)
Advancements in technology in mining have allowed previously unfeasible ore bodies to be developed. Paste backfill is one technological advancement that has allowed for the development of high-grade, low tonne production when employing the cut and fill mining method. Goldcorp Inc.'s Red Lake Mine currently utilizes this method and is the site for the study of this thesis. Paste backfill (paste) is defined as a mine backfill material that consists of eighty-five percent solids by weight and does not bleed water when placed often consisting of between two and fifteen percent Portland cement by weight. A paste barricade or paste fill fence is a constructed barricade whose purpose is to retain backfill within a mined out stope. The construction of the barricade varies with different operations, for Red Lake Mine the barricade consists of an anchored rebar skeleton covered with an adequate thickness of shotcrete. The majority of the applicable barricade research focuses on hydraulic fill barricades in open stope mining. The barricade pressures in these instances are much larger than those experienced in paste backfill barricades. As such, the current paste loading theory is based on material with a different loading mechanism. Although some research is currently underway, the majority of the barricade research is based on brick barricades and not the shotcrete, rebar skeleton as used at Red Lake. Catastrophic failures of barricades can occur without an understanding of the loading mechanisms. Based on the catastrophic risk, this thesis provides an investigation into the behaviour of the paste backfill and paste barricades at Red Lake Mine in order to provide a safe, cost effective design of paste barricades. This thesis develops an understanding of paste loading mechanisms and barricade capacity derived from a field study of nine instrumented fill fences at Red Lake Mine. Eight of thefences were instrumented to monitor the reaction strain in the fence and the applied pressures during standard production paste pours, the ninth fence was a controlled destructive test that determined the ultimate capacity of the fence. The data for these tests were gathered in real time and was subsequently reduced to assist in analysis. Yield Line Theory, Rankine Theory, strain induced stress, stress vs. strain analysis and numerical modeling were used to develop an understanding of the paste loading mechanisms and the capacity of the paste fill barricades. The analysis determined that the paste backfill behaves as a Rankine-like soil in the initial stages of loading with an average coefficient of lateral earth pressure, Ka, of 0.56. The destructive test determined that the yielding stress of a paste barricade is approximately 100 kPa. Further findings from the research determined that the rate of placement of paste does effect the loads applied to the fence and that the largest pressures exerted on the fill fence occur when paste lines were flushed with water at the end of the pour. This thesis provides an understanding of the paste loading and fill fence interaction with respect to failure. Based on this research the Red Lake Mine should be able to increase production without increasing risk to mine personnel by quantifying the overall loading and strengths of the fill barricade.
13

Spatial And Temporal Trends In Sediment Dynamics And Potential Aerobic Microbial Metabolism, Upper San Pedro River, Southeastern Arizona

Hamblen, Jennifer M. January 2003 (has links) (PDF)
Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 241-246).
14

Performance of paste fill fences at Red Lake Mine

Hughes, Paul B. 05 1900 (has links)
Advancements in technology in mining have allowed previously unfeasible ore bodies to be developed. Paste backfill is one technological advancement that has allowed for the development of high-grade, low tonne production when employing the cut and fill mining method. Goldcorp Inc.'s Red Lake Mine currently utilizes this method and is the site for the study of this thesis. Paste backfill (paste) is defined as a mine backfill material that consists of eighty-five percent solids by weight and does not bleed water when placed often consisting of between two and fifteen percent Portland cement by weight. A paste barricade or paste fill fence is a constructed barricade whose purpose is to retain backfill within a mined out stope. The construction of the barricade varies with different operations, for Red Lake Mine the barricade consists of an anchored rebar skeleton covered with an adequate thickness of shotcrete. The majority of the applicable barricade research focuses on hydraulic fill barricades in open stope mining. The barricade pressures in these instances are much larger than those experienced in paste backfill barricades. As such, the current paste loading theory is based on material with a different loading mechanism. Although some research is currently underway, the majority of the barricade research is based on brick barricades and not the shotcrete, rebar skeleton as used at Red Lake. Catastrophic failures of barricades can occur without an understanding of the loading mechanisms. Based on the catastrophic risk, this thesis provides an investigation into the behaviour of the paste backfill and paste barricades at Red Lake Mine in order to provide a safe, cost effective design of paste barricades. This thesis develops an understanding of paste loading mechanisms and barricade capacity derived from a field study of nine instrumented fill fences at Red Lake Mine. Eight of thefences were instrumented to monitor the reaction strain in the fence and the applied pressures during standard production paste pours, the ninth fence was a controlled destructive test that determined the ultimate capacity of the fence. The data for these tests were gathered in real time and was subsequently reduced to assist in analysis. Yield Line Theory, Rankine Theory, strain induced stress, stress vs. strain analysis and numerical modeling were used to develop an understanding of the paste loading mechanisms and the capacity of the paste fill barricades. The analysis determined that the paste backfill behaves as a Rankine-like soil in the initial stages of loading with an average coefficient of lateral earth pressure, Ka, of 0.56. The destructive test determined that the yielding stress of a paste barricade is approximately 100 kPa. Further findings from the research determined that the rate of placement of paste does effect the loads applied to the fence and that the largest pressures exerted on the fill fence occur when paste lines were flushed with water at the end of the pour. This thesis provides an understanding of the paste loading and fill fence interaction with respect to failure. Based on this research the Red Lake Mine should be able to increase production without increasing risk to mine personnel by quantifying the overall loading and strengths of the fill barricade. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate
15

Scour and fill in a gravel-bed channel : observations and stochastic models

Haschenburger, Judith Kay 05 1900 (has links)
This study investigates channel bed scour and fill as a result of individual flood events in a gravel-bed channel. Given the complexity of interactions between hydraulic force, the texture and arrangement of bed material, and input of sediment to a particular point of the channel bed, study objectives were pursued with the view that bed material movement is a stochastic phenomenon. A two-year field program was conducted in Carnation Creek, a small gravel-bed stream draining 11 km2 on the west coast of Vancouver Island, British Columbia. In the 900 m study reach, an array of measurement techniques, including scour indicators, magnetically-tagged stones, and conventional survey, yielded information about the fluctuations of the channel bed elevation and movement of scoured material for individual flooding periods. Frequency distributions of scour and fill depths associated with individual flooding periods are adequately modeled by negative exponential functions over the range of flood peak magnitudes observed in Carnation Creek. Analysis of scour depths measured in streams on the Queen Charlotte Islands demonstrates the applicability of the exponential model to flooding periods and flood seasons. Further, exploratory analysis suggests that a regional scour depth model is possible. Power functions relating mean depths of scour and fill to flood peak discharge show that depth increases with an increase in peak magnitude. Observed maximum scour depths in flooding periods are linked, in general, to streambed conditions influenced by antecedent flow conditions. These patterns in scour and fill exist within an overall pattern of increasing variability in depths of scour and fill as peak discharge increases. Evaluation of a heuristic model for mean travel distance as a function of particle size proposed by Church and Hassan (1992) provides convincing evidence for its general merit. Mean travel distance decreases inversely with particle size as size increases beyond the median diameter of subsurface sediment. This trend is consistent in both individual flooding periods as well as flood seasons. The majority of material finer than the median diameter of surface sediment is supplied from subsurface material, which influences the travel distances of these finer fractions because of burial. Computation of volumetric transport rates of bed material, based on the active scour depth and width of the channel bed, the virtual velocity of particle movement, and sediment porosity, suggests the potential for building scale correlations with streamflow, which have usually been defined by bedload sampling during floods. Error analysis indicates that determination of active width contributes most significantly to the imprecision of transport rate estimates. Results underscore the stochastic nature of sediment transport in gravel-bed channels. / Arts, Faculty of / Geography, Department of / Graduate
16

Proposal of Flowable Fill Designs for improvement of excavation and filling works of trenches in sanitation systems

Cruz, J., Cruz, J., Ñiquin, J., Bragagnini, I., Sotomayor, C. 28 February 2020 (has links)
Population grow in recent years requires an extension of the current pipeline sanitary system. For this purpose, granular excavation and landfill works are associated with pedestrian traffic congestion. Therefore, it is necessary to develop an innovative and sustainable alternative to reduce the problems generated during the execution of the conventional process. This research proposes the use of flowable fill due to the multiple advantages offered by this material. On the one hand, it is economical for medium to large trench fill volumes, considering savings in labor (it is done with a small number of workers), in equipment (does not require the rental or purchase of compaction equipment) and in time (the pouring is done by directly pumping the mixture, from the mixing machines to the excavation). On the other hand, being self-compacting and self-leveling decreases the width of the trenches, reducing excavation and filling volumes; which, in turn, incur money savings. Also, this material guarantees work safety, since people are not required inside the excavation and fill in poorly accessible areas without any problem. Dosages were established for ten flowable fill mixtures with cement contents of 50, 60, 70, 80 and 90 kg of cement and a range of admixture from 1.75 to 2.00%; The results indicated that decreasing the fine aggregate - coarse aggregate ratio, the compressive strength of the mixtures increases and the slumps of the mixtures decreases, and the compressive strength increases directly proportional to the cement content.
17

Estimating the potential for natural ecosystem recovery at the Pietersielieskloof palmiet wetland, Western Cape.

Mamphoka, Monkgane Faith January 2019 (has links)
Doctor Educationis / Recent research has highlighted the importance of cut-and-fill cycles in valley-bottom wetlands. This study considers the impact of longitudinal and lateral sediment connectivity on the natural recovery potential of valley-bottom wetlands. Pietersielieskloof is a Prionium serratum (commonly known as palmiet) dominated discontinuous valley-bottom wetland. P. serratum is considered to be a peat-forming ecosystem engineer that enhances sediment infill in valleybottom wetlands. Due to its ecological importance and potential as a carbon store, this wetland has been earmarked for rehabilitation by Working for Wetlands. The study ascertains the importance of including sedimentological and geomorphological input in wetland rehabilitation and management strategies. A study of wetland geomorphology was conducted to develop an understanding of the natural dynamic of cut-and-fill processes as context for recent erosion and deposition events. Sediment samples from gully walls and cores were collected for organic content and particle size analysis and five sediment samples predating the current phase of erosion were radiocarbon dated. The valley form was surveyed using cross-sections and long profiles, and historical change was digitised using 30 m – 5 to 30 mm resolution aerial imagery from 1938-2016 in ArcMap.
18

The stratigraphy,chronology and palaeoenvironment of The Pleistocene Cave Fill, Gladysvale Cave, South Africa

Pickering, Robyn 22 March 2006 (has links)
Master of Science - Science / The South African hominin bearing caves have yielded a wealth of early hominin and other faunal material, which has been the subject of many studies. Little work, however, has been undertaken on the cave fills themselves, as the breccias are complex, poorly stratified, highly calcified, inadequately exposed and too old to date by conventional radiometric means (Partridge, 2000). Gladysvale Cave is an exception to this, as the younger, internal deposits are well exposed from mining, are extremely well stratified, and are preliminarily dated to between 200 and 250 kyr, making this an ideal location to document the three dimensional stratigraphy and sedimentology of a cave fill fan and to test other models of cave sedimentation. The chronostratigraphic approach of Moriarty et al. (2000) was used to divide the deposit at Gladysvale into flowstone bounded units (FBU). The younger, internal deposit at Gladysvale was shown to consist of six major FBU and two minor ones, which in general occur throughout the cave. Binding flowstones are not always present, and are limited to areas directly below and in close proximity to major palaeodrip sources. The majority of sediment entered the cave through a single, central entrance and then split into two lobes around a number of stalagmitic bosses. This entrance eventually choked, and final stage sedimentation entered through a slit-like entrance across the front wall of the cave. As accommodation space inside the cave is fixed, the morphology of the units is defined by their relative position in the cave and the topography of the underlying units. Six major facies types are described, and facies changes from the proximal to distal portions of the deposit are described. Facies changes in time were controlled by the sediment supply rates. A number of intercalated flowstones and stalagmites were dated via ICP-MS Uranium-series dating, and despite problems with detrital contamination, ten reliable and robust dates were acquired, only three of which required correction for excess 232Th. The internal fan deposit is between ~570 and 7 kyr, making it both older and younger than previously thought. The dated speleothems all grew in the recovery period following a full interglacial or major inter stadial, indicating that these were periods of increased effective precipitation, during which the cave entrance was restricted to incoming clastic sediment. The dated flowstones show good concordance with the rainfall record of the Tswaing Impact Crater, and this record was used to generate an age model for the undated flowstones and intercalated breccia units. Carbon and oxygen isotope analysis of the breccias and flowstones provided further climatic control. Oxygen isotopes are invariant between flowstone and breccia, and any original signature was most likely overprinted by the residence time of the groundwater in the dolomite host rock. Carbon isotopes show more variation, and there is clear partitioning between flowstone and breccia, and ä13C values are interpreted as representing changing amounts of C3 and C4 vegetation respectively. The C4 signal for the breccias is confirmed by the presence of granular soil micropeds seen in thin sections. The succession of flowstones and breccias, the U-series dates and the stable light isotope data provide a ~600 kyr record of terrestrial climate change, which is, to date, the oldest such record for southern Africa, and shows excellent concordance with various other climate change records, both global, local and marine. The synchronicity of these records suggests a strong allocyclic control, which is attributed to changes in atmospheric circulation, in particular the size and position of the circumpolar vortex above Antarctica. A climatically controlled model for the nature and rate of sedimentation at Gladysvale Cave is proposed, in which flowstones grow during the warm, wet recovery period following full interglacials, during which C3 vegetation dominates and cave entrances are restricted. Sediments are washed into more open caves, during arid, C4 dominated conditions, corresponding to glacial periods. As this model is climatically controlled, and the Cradle of Humankind World Heritage Site is a relatively small area, the other caves in the area would have experience the same conditions, and if open at the time should contain fills of similar ages. This study has shown the value of the cave fills themselves, which are often understudied. The breccias at Gladysvale are strongly climatically controlled, being deposited only once certain climactic thresholds are crossed, hence producing a highly punctuated record. The hominin and other faunal remains from these caves should be viewed within this context. Gladysvale Cave also contains a ~600 kyr record of climate change, which will contribute to our understanding of terrestrial climatic changes and the landscape’s response to them.
19

Influência da técnica restauradora/ciclagem mecânica na adesão à dentina de pré-molares superiores / Influence of restorative technique/mechanical cycling on dentin adhesion of upper premolars

Matos, Laís Lopes Machado de 27 January 2017 (has links)
A resina bulk fill vem ampliando as indicações dos compósitos na qual permite a inserção em incrementos com espessura de até 5mm. A interface adesiva é a principal responsável pela durabilidade de restaurações estéticas. Objetivo: Avaliar a integridade da interface dente/restauração, e a resistência adesiva da dentina após a ciclagem mecânica de dentes restaurados com a resina bulk fill. Materiais e Métodos: Foram selecionados 40 prémolares superiores birradiculares que receberam um preparo MOD com término cervical mesial em esmalte e o término distal em dentina e foram divididos em 2 grupos: 1 incremento de resina e 2 incrementos de resina, e, dois subgrupos: com e sem ciclagem mecânica (n=10). Em seguida, os espécimes foram restaurados, analisados inicialmente em microscopia confocal a laser e posteriormente levados para ciclagem mecânica onde foram realizados 300.000 ciclos na frequência de 1Hz e carga de 80N. Após a ciclagem mecânica, os espécimes foram novamente avaliados em microscopia confocal a laser para avaliação da qualidade da interface, e foi realizado o teste de microtração na dentina das paredes proximais e pulpar dos dentes com ciclagem e sem ciclagem. Posteriormente, foi realizada a análise do padrão de fratura em microscopia confocal a laser. Os valores obtidos na mensuração de gaps foram analisados estatisticamente através da ANOVA seguido de Holm-Sidak; e os valores obtidos na microtração foram analisados estatisticamente através da ANOVA seguido de Tukey. Resultados: Observou-se que o fator incremento promoveu diferença estatística significante tanto em esmalte como em dentina antes e após a ciclagem (p<0,05). A ciclagem promoveu fendas tanto para esmalte como para dentina (p<0,05). Para resistência adesiva não foi observada diferença entre os grupos de 1 e 2 incrementos antes e após a ciclagem (p>0,05), nem na dentina em suas diferentes porções ao comparar os incrementos (p>0,05), mas foi possível observar diferença significante antes e após a ciclagem nas diferentes regiões de dentina (p<0,05). Conclusão: Previamente à ciclagem mecânica, o fator incremento não afetou a interface, a resistência adesiva e os términos cervicais proximais. Posteriormente à ciclagem, a qualidade da interface foi afetada negativamente, o término cervical em dentina apresentou fendas maiores, mas a resistência adesiva se manteve. A ciclagem mecânica influenciou o aumento da quantidade de gaps e trincas e prejudicou a adesão, principalmente na dentina da região distal. / The bulk fill resin extended the composites indications in which it allows the insertion in increments with thickness of up to 5mm. The adhesive interface is the main responsible for the durability of aesthetic restorations. Objective: To evaluate the integrity of the tooth/ restoration interface and dentin adhesive resistance after mechanical cycling of restored teeth with bulk fill resin. Materials and Methods: 40 upper biradicular premolars were selected for the study and received a MOD preparation with mesial cervical terminus in enamel and the distal cervical terminus in dentin and were divided into 2 groups: resin in 1 increment and resin in 2 increments, and 2 subgroups: with and without mechanical cycling (n = 10). Afterwards, the specimens were restored, initially analyzed by confocal laser scanning microscopy and submitted to mechanical cycling with 300,000 cycles, 1Hz frequency and 80N load. After the mechanical cycling, the specimens were evaluated again in confocal laser scanning microscopy to evaluate the interface quality, and microtensile test was performed on the dentin of the proximal walls and pulp of the teeth cycled or not. Later, the analysis of the fracture pattern was performed in confocal laser scanning microscopy. The values obtained in the measurement of gaps were analyzed by ANOVA following test Holm-Sidak and microtensile were analyzed by ANOVA following test Tukey. Results: The increment factor promoted a significant statistically difference for enamel (p <0.05) and dentin (p <0.05) after cycling. The cycling promoted significant cracks for enamel (p <0.05) and dentin (p <0.05). No difference in adhesive resistance was observed between the groups of resin in 1 and 2 increments, before and after cycling. There was no difference in dentin adhesive resistance in the different portions when the increments were compared, but it was possible to observe a significant difference (p <0.05) in the different regions of dentin (p <0.05). Conclusion: Previously to mechanical cycling, the increment factor did not affect the interface, the adhesive resistance and proximal cervical terminus. After the cycling, the interface quality was adversely affected, the cervical terminus in dentin presented higher cracks, but the adhesive resistance remained. Mechanical cycling influenced in the increase of gaps and cracks number and impaired the adhesion, mainly in the dentin of the distal region.
20

Comparing Packet Fill Strategies in Ethernet-Based Data Acquisition Systems

Penna, Sérgio D. 10 1900 (has links)
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / Ethernet-based data acquisition systems are becoming more and more common in the Flight Test Instrumentation environment. Digitized analog sensor output and various other types of digital data is captured and inserted into Ethernet packets using a "packet fill" strategy that in general is under control of the user. This paper discuss and compares two strategies "FILL-TO-TIME" and "FILL-TO- SIZE" for the acquisition of ARINC-429 digital data bus.

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