10 research outputs found
Transient flows through an infinite saturated aquifer of zero slope
No full textCER60WLH68.Includes bibliographical references (page 13)
Flume studies of the transport of pebbles and cobbles on a sand bed
No full textCER61RKF80.December 1961.Includes bibliographical references.Submitted to the Bulletin of Geological Society of America for publication.During experiments on sediment transport and resistance to flow with a uniform 0.33 mm sand, data were taken on the movement of individual rocks having intermediate diameters from about 0.1 to 0.5 foot. The experiments were conducted in a flume 2-foot wide by 80-feet long and for most runs, depth was held constant at 0.5 feet. The experiments showed that rocks on sand bed moved downstream consistently only if the flow was in the upper regime; that is, only if the bed forms were plain bed, standing waves, or antidunes. The rocks moved at velocities that were approximately one half of the average veloc1ty of the water. With all bed forms in the lower flow regime (ripples, ripples superimposed upon dunes, and dunes), the rocks always moved upstream and down into the bed. That is, the rocks moved into a scour pocket that formed at the upstream side of the rock. The movement upstream and down into the bed is limited by and approximately equal to the distance below the original rock position of the minimum bed elevation plus approximately one-half the rock diameter. The data indicate that cross bedded sand deposits formed by the ripple or dune phases of transport would contain few, if any, pebbles or cobbles. Because of the flow, in at least the downstream reaches of most rivers is in the lower regime, the upstream movement and scour into the bed demonstrated in the experiment is an important factor in the sorting process
Dual channel stream monitor: discussion
No full textCER62DWH23.July, 1962.From: Journal of the Hydraulics Division, 1962
Some effects of fine sediment on flow phenomena
No full textCER63-DBS-EVR-WLH56.Includes bibliographical references (pages 45-46) and index.Fine material (bentonite and kaolin clays) dispersed in water has a very definite effect on the viscosity and specific weight of the fluid. Tests at 24° C. with a Stormer viscosimeter showed that the apparent kinematic, viscosity of an aqueous dispersion consisting of 10 percent by weight bentonite was 8.75 times greater than that of pure water, and a dispersion consisting of kaolin was 1.40 times greater. The change is viscosity and density of the fluid changes the fall velocity of the bed material. The effect of fin material on the fall velocity of the bed material can be determined, as a first approximation, with the visual accumulation tube by using aqueous dispersions of clay as the sedimentation liquid. The results from visual accumulation analyses are comparable to those obtained by computation using the Reynolds number, drag relation, and the viscosity of the aqueous dispersion of clay as obtained from the Stormer viscosimeter. Experiments conducted in flumes at Colorado State University demonstrated that when changes in fall velocity caused by the changes in fluid properties occurred, the form of bed roughness was altered. Resistance to flow and sediment transport, because they are dependent on the form of bed roughness, were appreciably affected
Some properties of water clay dispersions and their effect on flow
No full textCER61WLH62.Includes bibliographical references.Fine sediments dispersed in water affect the apparent viscosity and specific weight of the resulting dispersion. Tests at 24 degrees centigrade with a Stormer viscosimeter showed that the apparent kinematic viscosity for a 10 percent by weight water-clay dispersion of an impure bentonite was 8.75 times greater than that of distilled water. A 10 percent water-kaolin dispersion was 1.40 times more viscous than distilled water. The change in viscosity and density of the water-fine sediment dispersion changes the fall velocity of the bed material. The fall velocity distribution of the bed material can be determined, as a first approximation, with the visual accumulation tube apparatus when water-clay dispersions are the sedimentation media. The results are comparable to the fall velocities computed by using the Reynolds number-drag relation, the measured viscosity of the water-clay dispersion and the density of the dispersion. Experiments conducted in water- sand flows with and without bentonite in the flumes at Colorado State University demonstrated that with bentonite in the flow the changes in fall velocity of the bed material particles, resulting from the changes in fluid properties, altered the bed configuration. Because the resistance to flow and bed-material transport are dependent on the form of the bed, they were appreciably affected. Generally, as concentration of fine sediment increases with a constant rate of stream flow, flow resistance and transport of bed material always increase in the upper flow regime and sometimes decrease in the lower flow regime
A study of flow in alluvial channels: the effect of large concentrations of fine sediment on the mechanics of flow in a small flume
No full textCER60DBS44.Includes bibliographical references.A small flume study of the variance in resistance to flow, form of bed roughness, and total bed material transport caused by introducing large fine sediment concentrations into the flow over a sand bed.A flume study was made using a natural river sand as the bed material, median diameter = 0.54 millimeters. Clear-water flow was compared with flow containing from 6,000 to 65,000 parts per million of fine sediment (bentonite). The study shows that the form of bed roughness could be changed by adding sufficient fine sediment (bentonite) to the clear-water flow. The total bed material transport was decreased by 50 percent with increasing fine sediment concentration with the dune bed form and was increased by as much as 550 percent for the transition, standing wave, and anti-tune forms of bed roughness. Resistance to flow was less (C/√g increased by 45 percent) with fine sediment-laden flow than with clear-water flow for the dune, and transition bed forms; and was greater (C/√g reduced by 25 percent) for the standing waves and the anti-dunes. A narrow range of bentonite concentration for each form of bed roughness was established as a limit below which only minor changes in bed form, bed material transport, and resistance to flow occurred. The variation of the liquid proper ties, specific weight and viscosity, for water-bentonite dispersions were studied and their effect on the properties of the bed material particles measured. The fall velocity of the particles in a dispersion of 100,000 parts per million fine sediment in water was reduced to about one-half their fall velocity in clear water
Effect of fine sediment on the mechanics of flow
No full textCER60DBS10.Includes bibliographical references.The effect of a fine sediment (bentonite clay) on resistance to flow, bed material transport, and the mechanics of flow was studied in a large recirculating laboratory flume at Colorado State University. Concentrations of fine sediment investigated ranged from 0 to 42,000 ppm. The presence of the fine sediment increases the density and viscosity of the water, reduces the effective fall diameter of bed material, alters and under certain conditions changes the form of the bed roughness completely, decreases the resistance to flow in the tranquil flow regime, increases the resistance to flow when anti-dunes exist; and in general, increases the bed material transport particularly with anti-dune flow. Based upon the results of the study, it is possible to qualitatively predict the effect of various concentrations of fine sediment on flow phenomenon in the field. However, additional studies should be conducted to determine the effect of larger concentrations of fine sediment and other types of fine sediment
A comparison of real-world data on adjuvant treatment in patients with stage III BRAF V600 mutated melanoma – Results of systematic literature research
No full textBackground: Over the past decade, PD-1-based immune checkpoint inhibitors (ICI) and targeted therapies (TT) with BRAF and MEK inhibitors transformed melanoma treatment. Both are widely used in the adjuvant setting. However, for patients with a BRAF V600 mutation, the optimal adjuvant therapy remains unclear due to the lack of head-to-head comparison studies. Methods: We conducted a systematic review of real-world data on adjuvant therapy in stage III melanoma to determine the best option for patients with BRAF V600 mutations. Kaplan-Meier curves were generated for TT and ICI using Digitizelt software. Results: Nine publications with 3625 patients were included. TT showed better relapse-free survival (RFS) at 6, 12, 24, and 36 months than ICI. A similar trend was observed for distant metastasis-free survival (DMFS), with no apparent difference in overall survival. Conclusion: Real-world data suggest that adjuvant TT may be associated with better RFS and DMFS in stage III BRAF V600-mutated melanoma compared to ICI.</p
