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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

Borehole Dimension Impact on LHD Operation in Malmberget Mine

Danielsson, Markus January 2016 (has links)
Sublevel caving is a highly mechanizable mass mining method normally utilized in large, steeply dipping orebodies. The fragmented ore flows freely, aided by gravity, down to the drawpoint while the surrounding waste rock caves in due to induced stresses and gravity. Fragmentation of the blasted ore is a vital component in any mining operation and directly affects productivity and efficiency of the following production steps (Nielsen et. al, 1996). In an attempt to reduce mining induced seismicity in Malmberget, LKAB is initiating various trials. One of these trials involves a reduction in blasthole dimension and an increase in the number of blastholes utilized in each ring. A reduction in blasthole dimension is undertaken to achieve a less impactful mining operation in terms of disturbances to surface populated areas, particularly addressed to ground vibrations. Therefore, it is of utmost importance to analyse if fragmentation and production is affected as a consequence of this change. This thesis sets out to evaluate how fragmentation and the LHD operation is affected by variations in blasthole dimension. The evaluation is carried out through analysis of logged production data, on-site filming of the loading sequence and interviews with the LHD operators. The discoveries will be presented chronologically to illustrate the complexities related to compiling a viable dataset to rely on for a credible analysis. The initial theory did not hold up properly and therefore the project was reshaped along the course of progression to provide further information and clarify uncertainties. Unfortunate, major production delays inhibited a quantitative comparison of two parallel drifts with different blasthole dimensions. Hence, no final answer can be provided in this thesis whether a change in blasthole dimension causes any differences in loadability and/or fragmentation or not. However, an analysis of how cycle times vary depending on causes such as operator induced differences, machine induced differences and road conditions will be provided. The field test also provides information on various loading scenarios and the difficulties connected to these. The result obtained in this project mainly addresses the significant operator difference in terms of cycle times which can extend to, on average, 60% depending on experience, road conditions and, most likely, preferences amongst operators. Time differences amongst seemingly experienced operators can reach more than, on average, 30% in hauling time alone. Roughly 96% of the operators state that road conditions in the production area is the controlling factor for hauling speed. Many of the operators further states that the risk of injuries is directly related to road conditions and this is a likely cause to why cycle times vary in this magnitude. Fragmentation was found to affect loadability but not to the same extent as shape and looseness of the muck pile. Compaction of the muck pile and flow disturbances where normally found to be connected to one another. Hence, good loadability would indicate a low occurrence of flow disturbances and a continuous flow of material into the drawpoint. This thesis is written as a part of the final stage of the civil engineering program at Luleå University of Technology (LTU) and represents 30 credits in the field of Soil and Rock Construction. The thesis is a part of a larger project, Face to surface, which sets out to analyse the impact of fragmentation on different stages in the production chain.
12

Modernism and fragmentation

Timmer, Cornelis, University of Western Sydney, Faculty of Performance, Fine Arts and Design, School of Design January 1998 (has links)
The aim of my dissertation, as the title indicates, is to determine the relationship between modernism and fragmentation. The objective, however, is twofold. In addition to the argument through which I explicate the neglected discussion of the connection between modernism and fragmentation, this paper reveals the thought processes and artistic influences crucial to my own development as a painter. The majority of artists I discuss have informed my practice stylistically as well as aesthetically. The thesis therefore serves not only as a theoretical discussion but also as a partial justification of my personal conceptions regarding my work, on which I will elaborate in appendix. This paper demonstrates that the resolution of all things depends upon the collection, selection, arrangement and rearrangement of fragments, including my painting and this paper itself / Master of Arts
13

Spatial distribution and movement of the common shrew (Sorex araneus) and the pygmy shrew (Sorex minutus) in a heterogeneous landscape

Lewis, Alexandra J. G. January 1999 (has links)
No description available.
14

Production of nuclei near the neutron drip-line by projectile fragmentation

Kwan, Elaine. January 2006 (has links)
Thesis (Ph. D.)--Michigan State University. Dept. of Physics and Astronomy, 2006. / Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 124-130). Also issued in print.
15

Resonance production and nuclear fragmentation for space radiation

Norman, Ryan Bradley. January 2008 (has links)
Dissertation (Ph.D.)--Worcester Polytechnic Institute. / Keywords: nuclear physics, particle physics, phyiscs, resonance, nuyclear fragmentation, nucleon-nucleon interactions, radiation shileding, heavy-ion physics, space radiation. Includes bibliographical references (leaves 163-141).
16

Contribution à la physique du procédé de mécanosynthèse /

Chen, Ying. January 1992 (has links)
Th. univ.--Sci. des matériaux--Paris 11, 1992. N°: 2284. / Bibliogr. p. 19-21. Résumé en français et en anglais.
17

Ejection of large fragments in high-energy nuclear reactions

Crespo, Vitor Pereira. January 1961 (has links)
Thesis (Ph.D.)--University of California, Berkeley, 1961. / "UC-34 Physics" -t.p. "TID-4500 (16th Ed.)" -t.p. Includes bibliographical references (p. 55-61).
18

Contribution à l'étude des grands systèmes : saisie et traitement des informations appliqués à la modélisation d'un circuit industriel de broyage à sec de talc.

Jacquemin, Pierre, January 1900 (has links)
Th. doct.-ing--Génie géol. et minier--Nancy--I.N.P.L., 1980.
19

Modélisation d'un processus minéralurgique : approche expérimentale de la dynamique du broyage discontinu et simulation.

Saint-étienne, Victor, January 1900 (has links)
Th. 3e cycle--Génie géol. et minier--Nancy--I.N.P.L., 1979.
20

Assessing the Impacts of Habitat Fragmentation on Biodiversity Across Scales: The Case of Thousand Island Lake, China

January 2018 (has links)
abstract: Habitat fragmentation, the loss of habitat in the landscape and spatial isolation of remaining habitat patches, has long been considered a serious threat to biodiversity. However, the study of habitat fragmentation is fraught with definitional and conceptual challenges. Specifically, a multi-scale perspective is needed to address apparent disagreements between landscape- and patch-based studies that have caused significant uncertainty concerning fragmentation’s effects on biological communities. Here I tested the hypothesis that habitat fragmentation alters biological communities by creating hierarchically nested selective pressures across plot-, patch-, and landscape-scales using woody plant community datasets from Thousand Island Lake, China. In this archipelago edge-effects had little impact on species-diversity. However, the amount of habitat in the surrounding landscape had a positive effect on species richness at the patch-scale and sets of small islands accumulated species faster than sets of large islands of equal total size at the landscape-scale. In contrast, at the functional-level edge-effects decreased the proportion of shade-tolerant trees, island-effects increased the proportion of shade- intolerant trees, and these two processes interacted to alter the functional composition of the regional pool when the total amount of habitat in the landscape was low. By observing interdependent fragmentation-mediated effects at each scale, I found support for the hypothesis that habitat fragmentation’s effects are hierarchically structured. / Dissertation/Thesis / Doctoral Dissertation Biology 2018

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