Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 37 for “"Ploughing"”.
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Shearing, ploughing, and wear in orthogonal machining
… tool, force components due to the rubbing and ploughing of the edge or wear land becomes significant. Predicting forces--and therefore other process outputs such as machined part quality--under these conditions requires an estimate of the effects of ploughing and wear. Furthermore, both …
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The performance of pipeline ploughs
… non-velocity dependant resistance of the plough. Ploughing tests were conducted at various relative densities in three sands of different permeability. The effects of ploughing rate on model plough behaviour under these various conditions was explored using an instrumented model plough, with …
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The potential for environmental management to contribute to malaria vector control in western Niger
… the form of leveling a topographic depression, ploughing the land surface to enhance infiltration and providing barriers to surface runoff on hillslopes. The hydrologic model described by Bomblies et al. (2008) was used for the modeling investigation, calibrated using environmental observations …
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Modeling and Analysis of Micro -End Milling Dynamics
… for which the cutting mechanisms vary from ploughing-dominated to shearing-dominated. The stability characteristics based on the regenerative effect that are unique in the micro-end mill have also been studied. Vibration contour maps have been generated to investigate the dynamic behavior of …
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Is local plant extinction a product of mutualism breakdown? A case study of the Namaqualand spring flora
… lands. Geophytes were completely eliminated by ploughing, however, the cause of their local extinction is not necessarily due to mutualism breakdown and may be explained by a lack of seed banks. The model was shown to be useful for predicting distribution patterns for annuals. However, further …
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The effects of grassland management practices, and the role of hedgerows, on farmland carbon sequestration and storage
… grassland reseeding, during spring and autumn ploughing events, and land use change from grassland to cropland. The role that hedgerows play in agricultural landscapes to sequester and store carbon was also investigated as these ubiquitous features are routinely missing from carbon assessments. …
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Investigation of the critical specific gravity for cables and pipelines during various backfilling and installation processes
… of pipelines/cables can be achieved using either ploughing or jet trenching with remotely operated vehicles.<br/><br/>In this thesis the issues arising while embedding pipelines and cables using jet trenching and backfill ploughing were investigated by means of scaled physical model tests. The …
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The effects of shrub removal and grazing on vegetation and soils in a shrub-encroached Australian woodland
… effects of mechanical shrub removal by blade−ploughing, with and without grazing, on vegetation and soils in shrub−encroached woodlands in eastern Australia. The results show that the combination of ploughing and grazing creates dramatic effects on soils and vegetation in this dryland system. …
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Palaeoecology and vegetation dynamics in the Cederberg wilderness area
… in the fire regime, combined with disturbance by ploughing and grazing have increased the abundance of Poaceae and Cyperaceae, resulting in a decrease in Restionaceae. Ploughing affected the height structure and species composition of the site, and allowed the invasion and persistence of exotic …
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Analytical model for force prediction when machining metal matrix composites
… were considered including: shearing force, ploughing force, and particle fracture force. Chip formation force was obtained by classical orthogonal metal cutting mechanics and the Johnson-Cook Equation. The ploughing force was formulated while the fracture force was calculated from the slip …
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Evaluating abrasive wear resistance of extruder tooling materials using the dry sand rubber wheel abrasion test
… mechanism for the composite materials, with some ploughing and microcutting, while ploughing and microcutting were the primary mechanisms in the wear of the steels. Evaluation of parts made from a composite material which were removed from service indicated that matrix erosion was the primary wear …
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Abrasive wear testing of steels in soil
… The removal of material through predominantly ploughing or cutting mechanisms has been shown to be dependent on the heat treatment and composition of the steels together with the nature of the abrasive. White surface layers have been observed to form on medium and high carbon steels subjected …
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Hydrodynamic characterisation of soil subsurface flows for water conservation purposes.
… sample before it is further agitated to simulate ploughing and subsequent infiltration experiments are carried out on it, making four samples on the whole. The Van Genuchten model of the soil water characteristics curve has been used for the verification of the experimental data. The volumetric …
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The impact of agricultural modernization on women's activities
… modernization perform additional tasks such as ploughing, application of fertilizers and pesticides, shelling, bagging and transporting the crop to the markets.This study, therefore, concludes that agricultural modernization leads to an increased involvement of women in agriculture. Finally, the …
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The impact of agricultural modernization on women's activities
… modernization perform additional tasks such as ploughing, application of fertilizers and pesticides, shelling, bagging and transporting the crop to the markets.This study, therefore, concludes that agricultural modernization leads to an increased involvement of women in agriculture. Finally, the …
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Understanding the friction between human fingers and contacting surfaces
… rectangular ridged surfaces are adhesion, ploughing friction and a reduction in friction force due to an energy return from the finger forming back to its original shape. These tests showed that for a large friction force, surfaces should have high, narrow and widely spaced ridges. This, …
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The Mechanisms of wear of the video head
… the head is an abrasive process characterised by ploughing of the ferrite surface and chipping of the edges of the head gap. Both phenomena appear to be caused by poor iron oxide and head cleaning particles, which create isolated asperities on the tape surface.
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The mechanics of power hacksawing and the cutting action of blunt tools
… cutting, some new light is thrown upon the ploughing process.</p> <p>A slip-line field is proposed which qualitatively represents the assumed chip formation mechanism under steady state cutting conditions. The application of an empirical relationship between the chip tool contact length and …
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A biophysical analysis of the occlusal wear of dental materials
… mm at 300K masticatory cycles) demonstrated a ploughing effect on the surface supporting an abrasive wear mechanism. The composite wear was intermediate(volume .046 .007 mm^3, depth .059 .01 mm). Posterior composites are thought to wear by an abrasive as well as fatigue mechanism. The …
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