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 34 for “"sand bed"”.
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Vertical Velocity Distributions in Sand -Bed Alluvial Rivers
… average percent error of 22.2% when the smaller bedforms were used as the geometry in the Nelson-Smith method.
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Sand bed morphodynamics under water waves and vegetated conditions
… bathymetric features, which include large-scale sand bars upon which smaller-scale sand ripples are superimposed, as well as the presence of submarine vegetation. As a result, understanding the complex interaction among these features is imperative to determining coastline morphological changes …
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Fractional transport of bed-material load in sand-bed channels
… for predicting fractional transport rates of bedmaterial load in sand-bed channels. The proposed method is developed based on the concept of the transport capacity fraction (TCF) approach. The bed-material concentration for a given size fraction is obtained by weighting the bed-material …
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The spatiotemporal evolution of fine tailings in sand-bed rivers
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-12-01
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Bathymetric evolution of sand bed forms under partially standing waves
… interaction between water waves and a movable sand bed were investigated. Monochromatic and poly- chromatic waves of specified amplitudes and period were generated under cases of weak (R=0.2) and/or strong (R=0.9) reflections. Experiments included one of two mean grain sand sizes (0.2mm and …
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Bacterial and Sediment Transport in an Artificial Sand Bed Stream During Unsteady Flow
… water velocity, size and transport rates of bed sediments, and the FIB concentration in bed sediment. The objective of this work is to determine the effect of varying flow rates on the transport of bed-dwelling coliforms in sand bed streams. Artificial stream experiments were run with …
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How do sand-bed meandering rivers co-construct their own bankfull discharge and bankfull channel geometry? Analytical and numerical study
… channel shift, and iv) in-channel downstream bed material transport. The flow duration curve is casted so as to quantify the effect of these processes, as well as to account for the flow variability. This new model captures the spatiotemporal evolution of bankfull discharge, depth, width, and …
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Expanding the stratigraphic record of tsunami inundation along the semi-arid, siliciclastic coast of north-central Chile
… the site. The 2015 tsunami deposit and an older sand bed ~10 cm lower in the stratigraphy exhibit similar sedimentological characteristics. Both sand beds are composed of poorly to moderately sorted, gray-brown, fine- to medium-grained sand and are distinct from underlying and overlying …
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Depositional environments of the upper part of the Sentinel Butte Formation, southeastern McKenzie County, North Dakota
… interval is the top of the upper yellow marker bed. </p><p> An elongate, tabular sand bed was studied in detail. It is 12 meters thick and 3 kilometers wide and it is interpreted to have been deposited by lateral accretion in a high-sinuosity stream. Paleo current indicators are parallel to the …
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Numerical Simulation of the Propagation of Fine-Grained Sediment Pulses in Alluvial Rivers
… of these sediment-flow hazards in alluvial sand-bed rivers. Specifically, the study presented herein is divided into three separate parts to achieve this overarching goal. First, a component intended to improve the numerical modeling of morphodynamic processes in alluvial sand-bed rivers by …
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Non-Lignite Marker Beds in the Sentinel Butte formation, McKenzie and Dunn Counties, North Dakota
<p>Non-lignite marker beds in the Sentinel Butte Formation have been noted by several authors (Fisher, 1953; Meldahl, 1956; Clark, 1966; Royse, 1970; Cherven, 1973; Johnson, 1973). Five non-lignite marker beds listed by Royse (1970): 1) basal sand bed, 2) blue bed, 3) lower yellow bed, 4) upper …
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Developing a novel mechanistic model for four-phase oil-water-gas-sand stratified flow in a horizontal pipe.
Presence of sand and solid particles in untreated petroleum sometime is inevitable. Although many techniques have been developed to prevent sand particles from entering the pipeline, such as downhole gravel packs, these downhole sand control devices can cause significant production loss due to the …
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Distinguishing flood frequency and magnitude in the morphodynamics and sedimentology of rivers: insights from the South Saskatchewan River, Canada
… flood on the morphology and sedimentology of the sandy braided South Saskatchewan River, Canada was assessed. Comparison of 2004 - 2007 repeat GPR surveys and the production of DEMs of difference allowed quantification of the initial and long-term 2005 flood impact on reach morphology and …
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Stratigraphic and microfossil evidence of repeated late Holocene tsunami inundation at Sitkalidak Island, Alaska
… reveal three anomalous, laterally continuous sand beds with sharp upper and lower contacts preserved within a coastal peat sequence. The microfossil and lithostratigraphic characteristics of the sand beds, including the presence of anomalous marine planktonic diatoms, high fragmentation of …
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Trapping Efficiencies for the BLH-84, Helley-Smith, Elwha, and TR-2 Bedload Samplers
Bedload-trapping efficiencies for four types of pressure-difference bedload samplers – a standard Helley-Smith (intake-nozzle width and height of 76.2 mm x 76.2 mm), BLH-84 (76.2 mm x 76.2 mm), Elwha (203 mm x 102 mm) and Toutle River-2 (305 mm x 152 mm) a standard Helley-Smith, US BLH-84 (both …
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Development of the BASS rake acoustic current sensor : measuring velocity in the continental shelf wave bottom boundary layer
… concurrent LDV measurements over a natural sand bed in a flume. The single measurement accuracy of the BASS Rake is higher than that of the LDV and the multiple sample volumes confer other advantages. For example, the ability of the BASS Rake to image vertically coherent turbulent …
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Fate and transport of Asian carp eggs in spawning rivers
… as their diets overlap. Asian carp can lay thousands of eggs and have the potential to spawn up to three times per year. Moreover, there is a growing concern about Asian carp invading the Great Lakes, which could cause negative ecological and economic impact. Asian carp eggs are semi-buoyant and …
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Downstream suspended sediment dynamics of reservoir sediment flushing
… fine sediment transport in coarse immobile bed, which is a common phenomenon downstream of dams during flushing releases, dam removal and also in many mountain and canyon rivers, was investigated. Particularly, the dynamics of the downstream erosion and transport of fine sediments released …
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Wheel design optimization for locomotion in granular beds using resistive force theory
… sizes under many driving conditions in a common sand bed. How the relations may be derived alternatively by assuming Coulombic yielding and how the relations can be augmented to predict wheel performance in different ambient gravities is also explained. Next, a rotating-flap wheel that consists …
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Polyelectrolyte conditioning of ferric sulfate sludge
… sludge samples were applied to bench scale sand beds to determine the effect of conditioning on the dewatering rate of the sludge. Results indicated that all types of polyelectrolytes used reduced the specific resistance of the sludge. However, specific resistance was only a qualitative …
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