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1
Zhang, Zhiming, Sai Wu, Huimin Miao, and Tong Zhang. "Numerical Investigation of Flow Channel Design and Tapered Slope Effects on PEM Fuel Cell Performance." Sustainability 14, no. 18 (September 6, 2022): 11167. http://dx.doi.org/10.3390/su141811167.
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High-power proton exchange membrane (PEM) fuel cell vehicles are important for the realization of carbon neutrality in transportation. However, it is difficult to maintain enough fuel supply and quick water removal capacity at a high current density where reactant gas transportation and water concentration are directly affected by flow channel configurations. This study aims to investigate the tapered slope effects of a flow channel on fuel cell performance using a 3-D CFD model. The positive, negative, zero and hybrid tapered slopes are proposed to illustrate the fuel cell voltage, reactant gas and water vapor concentration in the flow channels. Among them, the flow channel with a positive tapered slope performs better, especially at a high current density. Then, the positive tapered slope effects are discussed, including different tapered slopes, inlet depths and widths of flow channels. The results show that the larger the tapered slope, the smaller the depth and width, and the better the fuel cell performs; the corresponding current densities are increased by a maximum of 6.53%, 12.72% and 61.13%. The outcomes stated above provide a key direction for flow channel design that can particularly achieve higher fuel cell power density at high current densities.
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Debabeche, Mahmoud, Sonia Cherhabil, Amin Hafnaoui, and Bachir Achour. "Hydraulic jump in a sloped triangular channel." Canadian Journal of Civil Engineering 36, no. 4 (April 2009): 655–58. http://dx.doi.org/10.1139/l08-136.
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The hydraulic jump in a sloped triangular channel of 90° central angle is theoretically and experimentally examined. The study aims to determine the effect of the channel's slope on the sequent depth ratio of the jump. A theoretical relation is proposed for the inflow Froude number as function of the sequent depth ratio and the channel slope. An experimental analysis is also proposed to find a better formulation of the obtained relation. For this motive, six positive slopes are tested. The relations obtained are recommended for designing irrigation ditches.
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Moldamuratov, Zh N., A. A. Iglikov, E. B. Madaliyeva, S. Zh Daurbekova, and A. Sh Asylbekov. "CROSS-SECTION CHANNELS OF HYDRAULICALLY AND STATICALLY STABLE SHAPE." Bulletin of Kazakh Leading Academy of Architecture and Construction 86, no. 4 (December 15, 2022): 199–209. http://dx.doi.org/10.51488/1680-080x/2022.4-20.
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The article presents the results of research on the substantiation of giving a stable shape of cross-section to the channels of hydro-reclamation systems of southern Kazakhstan. The calculations on the stability of irrigation channel slopes were made, as well as their design features and practical substantiation of stable profiles were presented. The shapes of stable slope were determined using of actual values of geotechnical parameters of slope soils. The results showed that the slope profile takes a stable shape during the channel operation, close to the parabolic.
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Huyghe, Pascale, Michel Foata, Eric Deville, Georges Mascle, and Caramba Working Group. "Channel profiles through the active thrust front of the southern Barbados prism." Geology 32, no. 5 (May 1, 2004): 429–32. http://dx.doi.org/10.1130/g20000.1.
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Abstract Submarine channels of the Orinoco River were analyzed using high-quality, dense- coverage bathymetric and seismic data provided by a recent marine survey on the southern Barbados prism. Analysis of the syntectonic sediments on seismic profiles shows that the four to five frontmost structures show evidence of recent tectonic movement. Slope analysis of the major channels was performed. From their headwaters to domains of little or no active tectonics, the channels display <0.2% slope and form levees. Slope and incision increase gradually in domains of moderate tectonics, but deep canyons with ∼2% mean slope form where the channels cross the active frontal folds of the prism. Detailed correlation between the active structures, their geometry, and canyon slope suggest that systematic variations in channel gradient highlight variations in substrate uplift rate. Steep slopes induced by uplift accelerate sediment flow and enhance incision. Nonetheless, such slope analysis is subject to complications introduced by variations in sediment flux and transient erosional conditions.
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Li, Guang Ming, Chun Yuan Liu, and Pei Chen. "Study on the Channel Slope Safe Stability." Applied Mechanics and Materials 256-259 (December 2012): 311–14. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.311.
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It is well known that the slope stability analysis is the core of the slope engineering study .The key of the study slope safety stability is optimize the slop coefficient。And the reasonable coefficient decides the design of slope type structure.This paper used the simplified Bishop method which according to the limit equilibrium theory as the foundation and the finite element numerical simulation to solve the south-to-north water transfer engineering slope instability problem.So it can provide the theory basis and design opinion for the slop construction engineering in the future.
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Locat, Jacques, Ali Azizian, Jim Stronach, Aurélien Hospital, Chris Young, Dominique Turmel, and Andrew Bevan. "Morphological signature of gully development by rapid slide retrogression in a layered coarse-grained delta foreslope." Geological Society, London, Special Publications 500, no. 1 (2020): 219–34. http://dx.doi.org/10.1144/sp500-2019-159.
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AbstractCoarse-grained deltas are often characterized by steep foreslopes (often more than 10°) that are traversed by delta-front channels. The channels thus erode into relatively steeply inclined bedding. In this context, the slopes flanking the channels can be steeper than the friction angle since they include a component of dip related to the delta-front slope as well as the channel-related erosion slope. In this study, part of the Busu River delta (Papua New Guinea) was imaged using a high-resolution multibeam bathymetry survey over an area where the angle of the slopes flanking the channels locally reaches 50°. A detailed analysis of the delta slope morphology has revealed an additional source of instability due to erosion within the main channels. In some places, erosion cuts into the channel flank forming a local knickpoint inclined in a direction approaching that of the bed dip. The cut can then initiate breaching or static liquefaction failure from that point up to the crest of the interfluve resulting in a V-shaped gully.
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Sümeghy, Borbála, and Tímea Kiss. "Morphological and hydrological characteristics of paleo-channels on the alluvial fan of the Maros River, Hungary." Journal of Environmental Geography 5, no. 1-4 (January 2, 2012): 11–19. http://dx.doi.org/10.14232/jengeo-2012-43803.
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The aim of our research was to identify and map the paleo-channel systems on the alluvial fan of the Maros River and to analyse their spatial characteristics. The study on flow directions, horizontal channel parameters and paleo-discharge of the channels can help to forecast the maximum flood discharge and channel changes influenced by climate variations. The paleo-channel generations on the Maros alluvial fan form 13 zones with well defined boundaries. These zones can be either dominated by meandering (5), braided (2), or the mixture of meandering and braided patterns (3). The remaining three paleo-channel zones exhibit an anastomosing pattern but they were not analysed in this study. The horizontal morphological parameters of the braided, the meandering and the misfit channels were measured. Based on these morphometric parameters and regional discharge equations the bankfull discharge of the meandering zones was calculated. The greatest discharge was around 2655 m3/s while the smallest was 27 m3/s in case of a misfit paleo-channel. Based on the slope conditions the alluvial fan was divided into three parts. The greatest slope (31.0 cm/km) was found in the central part of the alluvial fan, whilst slightly lower slopes (23.8 cm/km and 24.9 cm/km) characterise its axial and distal parts. These parameters refer to a normal radial profile of an alluvial fan. The channel pattern changes are in close relation with differences in slope. This is the most obvious in zone No. IX, where braided channels transform into meandering and then braided again from east to west in accordance with slope conditions.
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Harishidayat, Dicky, and Wasif Rehman Raja. "Quantitative Seismic Geomorphology of Four Different Types of the Continental Slope Channel Complexes in the Canterbury Basin, New Zealand." Applied Sciences 12, no. 9 (April 26, 2022): 4386. http://dx.doi.org/10.3390/app12094386.
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Modern marine seismic reflection data have allowed for the study of the morphology of submarine channels in a 3D perspective. This study presents a quantitative analysis of continental slope channel complexes morphology within the Canterbury Basin (New Zealand). It aims to characterize the morphology and seismic facies of submarine channels to better understand their formative sedimentary processes, paleoenvironment, and petroleum prospectivity. Submarine channel morphometric parameters are measured at 150 m intervals perpendicular to the axis of channels complexes. Based on the morphology analysis of erosional surfaces and seismic facies of channel complexes filling deposits, four types of continental slope channel complexes are found in the study area. These are vertical migrating channels, lateral migrating channels, V-shaped channels, and U-shaped channels. Furthermore, our work shows that channel morphometry varies over distances of 0.1 to 14 km in this continental slope system. These changes indicate a combination of submarine gravity flow process and channel wall collapse responsible for the development of continental slope channel complexes. Regionally, the evolution of the channels indicated less significant regional plate movement. This quantitative seismic geomorphology approach of characterizing submarine channels system has broader applications for better interpretation of paleoenvironment and petroleum prospectivity within frontier basins.
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Lee, Kyutae, Ali R. Firoozfar, and Marian Muste. "Technical Note: Monitoring of unsteady open channel flows using the continuous slope-area method." Hydrology and Earth System Sciences 21, no. 3 (March 30, 2017): 1863–74. http://dx.doi.org/10.5194/hess-21-1863-2017.
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Abstract. The advent of low-cost pressure transducers capable of directly measuring water surface elevation enables continuous measurements of dynamic water surface slopes. This opens up a new possibility of dynamically monitoring unsteady flows (i.e., hysteresis) during the course of flood wave propagation. Hysteresis in this context refers to a looped stage–discharge rating caused by unsteadiness of flows. Hysteresis is monitored in this study using a continuous slope area (CSA) method, which uses Manning's equation to calculate unsteady discharges based on continuously measured water surface slopes. In the rising stage, water surface slopes become steeper than a steady water surface slope, resulting in higher discharges than steady-based discharges, while the trends are reversed in the falling stage. The CSA method applied to Clear Creek near Oxford (Iowa, USA) estimates the maximum differences of peak discharges by 30–40 %, while it shows sound agreements for a low to medium range of discharges against USGS steady-based records. The primary cause of these differences is the use of a single channel bed slope in deriving Manning's roughness coefficients. The use of a single channel bed slope (conceptually equal to the water surface slopes at every stage in uniform flow conditions) causes substantial errors in estimating the channel roughness, specifically at high stages, because non-uniformities of natural channels result in varying (non-uniform) steady water surface slopes at each stage. While the CSA method is promising for dynamically tracking unsteady water surface slopes and flows in natural streams, more studies are still needed to increase the accuracy of the CSA method in future research.
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Jiongxin, Xu. "Channel pattern discrimination based on the relationship between channel slope and width." Zeitschrift für Geomorphologie 48, no. 3 (September 29, 2004): 391–401. http://dx.doi.org/10.1127/zfg/48/2004/391.
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Sougnez, N., and V. Vanacker. "Spatial variability in channel and slope morphology within the Ardennes Massif, and its link with tectonics." Hydrology and Earth System Sciences Discussions 7, no. 5 (September 16, 2010): 6981–7006. http://dx.doi.org/10.5194/hessd-7-6981-2010.
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Abstract. Geomorphic processes that produce and transport sediment, and incise river valleys are complex; and often difficult to quantify over longer timescales of 103 to 105 years. Morphometric indices that describe the topography of hill slopes, valleys and river channels have commonly been used to compare morphological characteristics between catchments and to relate them to hydrological and erosion processes. This work focuses on a wide range of slope and river channel morphometric indices to study their behavior and strength in regions affected by low to moderate tectonic activity. We selected 10 catchments of about 150 to 250 km2 across the Ardennes Massif that cover various tectonic domains with uplift rates ranging from about 0.06 to 0.20 mm year−1 since mid-Pleistocene times. The morphometric analysis indicates that the slope and channel morphology of third-order catchments is not yet in topographic steady-state, and exhibits clear convexities in slope and river profiles. Our data indicate that the fluvial system is the main driver of topographic evolution and that the spatial pattern of uplift rates is reflected in the distribution of channel steepness and convexity. The spatial variation that we observe in slope and channel morphology between the 10 third-order catchments suggests that the response of the fluvial system was strongly diachronous, and that a transient signal of adjustment is migrating from the Meuse valley towards the Ardennian headwaters.
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Liu, Da, Jianglin Gao, Fang Chen, Songtao Hu, Xiaohua Zhao, and Yan Li. "Analysis of Mechanical Properties and Slope Stability of Red Bed Soft Rock: A Case Study in Xinjiang Irrigation Diversion Channel." Advances in Civil Engineering 2022 (November 16, 2022): 1–9. http://dx.doi.org/10.1155/2022/9453702.
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The channel slope in the red-bed soft rock area is prone to instability and collapse due to the influence of the channel flow movement, rainfall, weathering, and other factors. Under long-term operation conditions, the sediment stripped from the channel side wall is liable to silt along the process of water flow transportation in the channel, which seriously leads to elevation of the channel bottom, increase of channel width, and reduction of the horseway, which affect the normal water conveyance and operation safety of channels. In view of the collapse and instability of Zhetang diversion irrigation channel project in Xinjiang hydraulic project, through on-site sampling and indoor rock mechanics test, the strength mechanical parameters of slope rock samples are obtained, and the indoor rheological test is carried out, and the triaxial rheological law is obtained. Under different levels of stress, the axial creep strain accounts for more than 50% of the total axial strain, indicating that the rheological effect of sample rock is obvious. Based on the strength parameters of rock samples, a numerical model is established. The stability of red-bed soft rock channel bank slope is studied by using the strength reduction method of finite element method. The seepage field of channel slope under conventional working conditions is analyzed, and the slope stability under different operating conditions is compared and calculated. The results show that the slope stability safety factor of Zhetang diversion irrigation channel slope is 1.60 under conventional working conditions and 1.33 under check working conditions, which are greater than the recommended value in the specification.
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Turowski, Jens Martin. "Alluvial cover controlling the width, slope and sinuosity of bedrock channels." Earth Surface Dynamics 6, no. 1 (February 6, 2018): 29–48. http://dx.doi.org/10.5194/esurf-6-29-2018.
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Abstract. Bedrock channel slope and width are important parameters for setting bedload transport capacity and for stream-profile inversion to obtain tectonics information. Channel width and slope development are closely related to the problem of bedrock channel sinuosity. It is therefore likely that observations on bedrock channel meandering yields insights into the development of channel width and slope. Active meandering occurs when the bedrock channel walls are eroded, which also drives channel widening. Further, for a given drop in elevation, the more sinuous a channel is, the lower is its channel bed slope in comparison to a straight channel. It can thus be expected that studies of bedrock channel meandering give insights into width and slope adjustment and vice versa. The mechanisms by which bedrock channels actively meander have been debated since the beginning of modern geomorphic research in the 19th century, but a final consensus has not been reached. It has long been argued that whether a bedrock channel meanders actively or not is determined by the availability of sediment relative to transport capacity, a notion that has also been demonstrated in laboratory experiments. Here, this idea is taken up by postulating that the rate of change of both width and sinuosity over time is dependent on bed cover only. Based on the physics of erosion by bedload impacts, a scaling argument is developed to link bedrock channel width, slope and sinuosity to sediment supply, discharge and erodibility. This simple model built on sediment-flux-driven bedrock erosion concepts yields the observed scaling relationships of channel width and slope with discharge and erosion rate. Further, it explains why sinuosity evolves to a steady-state value and predicts the observed relations between sinuosity, erodibility and storm frequency, as has been observed for meandering bedrock rivers on Pacific Arc islands.
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Sougnez, N., and V. Vanacker. "The topographic signature of Quaternary tectonic uplift in the Ardennes massif (Western Europe)." Hydrology and Earth System Sciences 15, no. 4 (April 4, 2011): 1095–107. http://dx.doi.org/10.5194/hess-15-1095-2011.
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Abstract. Geomorphic processes that produce and transport sediment, and incise river valleys are complex; and often difficult to quantify over longer timescales of 103 to 105 y. Morphometric indices that describe the topography of hill slopes, valleys and river channels have commonly been used to compare morphological characteristics between catchments and to relate them to hydrological and erosion processes. This study aims to analyze the link between tectonic uplift rates and landscape morphology based on slope and channel morphometric indexes. To achieve this objective, we selected 10 catchments of about 150 to 250 km2 across the Ardennes Massif (a Palaeozoic massif of NW Europe, principally located in Belgium) that cover various tectonic domains with uplift rates ranging from about 0.06 to 0.20 mm yr−1 since mid-Pleistocene times. The morphometric analysis indicates that the slope and channel morphology of third-order catchments is not yet in topographic steady-state, and exhibits clear convexities in slope and river profiles. Our analysis indicates that the fluvial system is the main driver of topographic evolution and that the spatial pattern of uplift rates is reflected in the distribution of channel steepness and convexity. The spatial variation that we observe in slope and channel morphology between the 10 third-order catchments suggests that the response of the fluvial system was strongly diachronic, and that a transient signal of adjustment is migrating from the Meuse valley towards the Ardennian headwaters.
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A.Merry, Marwa. "EXPERIMENTAL STUDY FOR DETERMINE MANNING'S COEFFICIENT WITH DIFFERENT SLOPES AND CHANNEL BED MATERIALS." Kufa Journal of Engineering 8, no. 3 (November 12, 2017): 76–88. http://dx.doi.org/10.30572/2018/kje/8031160.
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Water resources and hydraulic engineering projects have been upward rapidly in all over the world, accordingly the prediction of roughness coefficient is essential criteria to design open channels, and related hydraulic structures. The aims of this research are to find out the effect of changing beds materials and discharge on coefficient of roughness (n), the beds that used in the tests are smooth which represented by original channel bed (steel plate), rough bed material which is a gravel bed and waved bed .The experimental work was performed in a rectangular flume with dimension of (15 m* 0.3 m* 0.45 m) long, wide and deep, respectively with different value of slope (1:200 and 1:500) to analyze slope effect on coefficient of roughness in addition to the effect of channel bed material. The experimental work showed that The coefficient of roughness reduced when the discharge increases for specified slope and channel bed, The slope of the channel and bed roughness is the main factors affected on determining coefficient of roughness and when the channel slope increases the coefficient of roughness increases, the coefficient of roughness is decreased when using smooth bed and it is increased when channel bed is waved. The percentage change in the Manning coefficient due to changing in slope and channel bed is (112.6%) when slope equal to (1/200) and the channel bed changed from smooth to rough , (184%) when the bed changed from rough to waved, and (33.6%) when channel bed changed from rough to waved. And for (1/500) slope, the percentage change in the Manning coefficient equal to (33.5%) when the bed changed from smooth to rough, (80%) when changed from smooth to waved, and (33.1%) when changed from rough to waved.
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Sun, Hui, Bo Hu, and Guo Qiang Zhang. "Analysis of Fissured Expansive Soil Slope Stability and its Reinforcement with Anti-Slippery Piles." Applied Mechanics and Materials 275-277 (January 2013): 1489–92. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.1489.
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Fissure is one of the most important characteristics in expansive soil. It’s an important factor affecting slope stability in the expansive soil area. With the study of expansive soils typical channel slope fissured characters in the South-to-North Water Diversion Project, different impaction on slope stability such as location and inclination of the fissure are analyzed. By using the limit equilibrium method, the stability of expansive soil slope is analyzed; the most adverse condition of expansive soil slope is concluded. Then anti-slippery pile reinforcement in expansive soil channel slope is studied by using finite difference method. The research is of great significance to the construction and reinforcement of expansive soil slopes in South-to-North Water Diversion Project.
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Chitrakar, Suman, Scott N. Miller, Edward W. Kempema, Paul A. Caffrey, and Justin Stern. "Impact of Channel Slope on Cutthroat Flume Performance." Transactions of the ASABE 61, no. 1 (2018): 117–20. http://dx.doi.org/10.13031/trans.12468.
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Abstract. Cutthroat flumes are widely used in field projects to estimate discharge via a stage-discharge relationship. Flumes are commonly tested and calibrated in a laboratory to develop the stage-discharge relationship, but field installations often occur under non-idealized conditions, specifically with respect to bed slope. We calibrated a cutthroat flume with dimensions of 0.91 m length and 0.35 m throat width for bed slopes ranging from 0% to 2% to represent a range of field conditions. The experiment was conducted in the Water Resources Lab of the College of Engineering at the University of Wyoming, which provided highly accurate discharge measurements. Results showed negligible impact of slope on the resulting stage-discharge relationship under free flow conditions. We were able to generate a composite rating curve for bed slopes ranging from 0% to 2% for flumes of this size. Our study indicates that, under free flow conditions, longitudinal floor slopes ranging from 0% to 2% do not significantly affect the cutthroat flume rating curve. Keywords: Cutthroat flume, Flume calibration, Free flow, Rating curve, Stream discharge.
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El Bouanani, Latifa, Khadija Baba, Ghizlane Ardouz, and Fatimaezzahraa Latifi. "APPLICATION OF CONCRETE LOZENGES CHANNELS IN SLOPE EROSION PROTECTION." Journal of Southwest Jiaotong University 57, no. 4 (August 29, 2022): 262–71. http://dx.doi.org/10.35741/issn.0258-2724.57.4.23.
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Water erosion is a phenomenon that threatens not only agricultural land but also road and rail infrastructure. This article investigates the slope stability against water erosion for five embankments situated on the north axis and east axes of the Moroccan linear railroad infrastructure and proposes the use of concrete lozenges channels for slope erosion protection. Using RUSLE erosion model, the assessment of the sensitivity of these infrastructures to water erosion has enabled us to deduct the essential role of water, the type of soil and the slope inclination in triggering instabilities. The new concrete lozenges channel technique proposed by this paper makes it possible to improve a percentage decrease of the soil loss rate by more than 35%. Indeed, the soil loss rate reduction depends on the concrete lozenges channel number. An increase in this number decreases the soil loss rate. For a study case, the concrete lozenges channels were sized to define the number of lozenges necessary in the vertical and horizontal directions of the slope. Important parameters must be defined for this new technique design, namely, the inclined channel section and the ditch section. In fact, the concrete lozenges channel numbers decrease if the number of ditches and inclined channel sections increases. However, the stability of these drainage structures and the project budget must be studied to find an optimal design that considers the quality-price ratio.
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Arnold, D. J., Y. M. Stokes, and J. E. F. Green. "Thin-film flow in helically-wound rectangular channels of arbitrary torsion and curvature." Journal of Fluid Mechanics 764 (December 23, 2014): 76–94. http://dx.doi.org/10.1017/jfm.2014.703.
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AbstractLaminar helically-symmetric gravity-driven thin-film flow down a helically-wound channel of rectangular cross-section is considered. We extend the work of Stokes et al. (Phys. Fluids, vol. 25 (8), 2013, 083103) and Lee et al. (Phys. Fluids, vol. 26 (4), 2014, 043302) to channels with arbitrary curvature and torsion or, equivalently, arbitrary curvature and slope. We use a non-orthogonal coordinate system and, remarkably, find an exact steady-state solution. We find that the free-surface shape and flow have a complicated dependence on the curvature, slope and flux down the channel. Moderate to large channel slope has a significant effect on the flow in the region of the channel near the inside wall, particularly when the curvature of the channel is large. This work has application to flow in static spiral particle separators used in mineral processing.
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Mendonça, Vinícius V. O., César A. da Silva, Claudia R. O. S. G. Mendonça, Cícero J. da Silva, and Claudinei M. Guimarães. "Lettuce production in hydroponic and fish-farming aquaponic under different channel slopes and nutrient solutions in the NFT system." Revista Brasileira de Engenharia Agrícola e Ambiental 27, no. 9 (September 2023): 746–54. http://dx.doi.org/10.1590/1807-1929/agriambi.v27n9p746-754.
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ABSTRACT The slope of cultivation channels and types of nutrient solutions in hydroponics and aquaponics influence nutrient absorption and plant production. This research aimed to evaluate lettuce production under different channel slopes and nutrient solutions in hydroponic and aquaponic systems using the nutrient film technique (NFT). A randomized block design was used, with three replicates, in a 3 × 5 split-plot scheme, with three nutrient solutions (conventional hydroponic solution and two wastewaters from the tilapia fish diets, with 15 and 18% of crude protein) and five slopes (2, 4, 6, 8 and 10%) of cultivation channels (PVC tubes). The following variables were evaluated: fresh and dry mass of shoot and roots and the chemical elements of the solutions. In the tilapia feed, the nutrient solution with 18% of protein (wastewater) provides greater production and accumulation of nutrients (N and P) in the lettuce shoot. The slope of 8% on cultivation channels provides greater production of iceberg lettuce, cultivar Lucy Brown. The different slopes and nutrient solutions studied did not influence the potassium (K) accumulation in the lettuce shoot.
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Alibekov, A. K., and G. A. Аlibekov. "MODELS FOR DETERMINING MAXIMUM DEGREE FILLING CHANNELS OF CIRCULAR SECTION SHAPE." Herald of Dagestan State Technical University. Technical Sciences 46, no. 2 (August 28, 2019): 28–36. http://dx.doi.org/10.21822/2073-6185-2019-46-2-28-36.
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Objectives The task was to obtain a model for determining the maximum possible degree of filling the circular section channels in the earthen channel based on the condition of ensuring the stability of slopes and the minimum volume of excavation during their construction, as well as finding the optimum degree of filling fortified channels of a closed profile corresponding to maximum throughput.Method In work analytical methods of differential calculus and the solution of implicit equations are used.Result The experience of domestic and foreign researchers was taken into account to solve the set tasks, select research methods and criteria for optimizing channel parameters. Two cases of circular-shaped channels are considered: 1) in the earth channel, 2) reinforced with a closed transverse profile. For the case of a hydraulically most advantageous circular channel in the earthchannel channel, equating the first derivative of the equation of a circle with the reciprocal of the allowable embedding coefficient of the slopes obtained an analytical solution for determining the maximum degree of filling from the slope stability condition, which was not dependent on hydraulic flow elements. In the case of non-cohesive soils that form the channel, the circular channel can be filled to a depth not exceeding 20 percent of the channel radius. At the same time, the average flow rate should remain in the range from non-venting to non-blurring. In order to be able to determine the flow rate, analytical expressions are given for finding hydraulic flow elements in a circular channel. When determining the volume of excavation for the construction of the channel, the excess of the channel edge above the maximum water level in the channel was taken into account. For the case of a fortified channel of a closed transverse profile, by taking the derivatives from the Chezy formula, we obtained the optimal values of flow rate and average velocity.Conclusion A fortified closed circular profile channel has a maximum capacity with a relative degree of filling of 0.938, and the maximum average velocity of a fluid in a pressureless channel is achieved with a degree of filling of 0.815. To determine the maximum permissible relative degree of filling in the case of a circular section channel in the earthen channel, analytical dependences were obtained, before using which, according to the reference literature, it is necessary to take the value of the slope coefficient for this type of channel bed soil.
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GOLDING, MADELEINE J., and HERBERT E. HUPPERT. "The effect of confining impermeable boundaries on gravity currents in a porous medium." Journal of Fluid Mechanics 649 (April 13, 2010): 1–17. http://dx.doi.org/10.1017/s0022112009993223.
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The effect of confining boundaries on gravity currents in porous media is investigated theoretically and experimentally. Similarity solutions are derived for currents when the volume increases as tα in horizontal channels of uniform cross-section with boundary height b satisfying b ~ a|y/a|n, where y is the cross-channel coordinate and a is a length scale of the channel width. Experiments were carried out in V-shaped and semicircular channels for the case of gravity currents with constant volume (α=0) and constant flux (α=1). These showed generally good agreement with the theory.Typically, we find that the propagation of the current is well described by L ~ tc for some scalar c. We study the dependence of c on the time exponent of the volume of fluid in the current, α, and the geometry of the channel, parameterized by n. For all channel shapes, there exists a critical value of α, αc = 1/2, above which increasing n causes an increase in c and below which increasing n causes a decrease in c, where increasing n corresponds to opening up the channel boundary to the horizontal. The current height increases or decreases with respect to time depending on whether α is greater or less than αc. It is this fact, along with global mass conservation, which explains why varying the channel shape n affects the propagation rate c in different ways depending on α.We also consider channels inclined at an angle θ to the horizontal. When the slope of the channel is much greater than the slope of the free surface of the current, the component of gravity parallel to the slope dominates, causing the current to move with a constant velocity, Vf say, regardless of channel shape n and flux parameter α, in agreement with results for a two-dimensional gravity current obtained by Huppert & Woods (1995) and some initially axisymmetric gravity currents presented by Vella & Huppert (2006). If the effect of the component of gravity perpendicular to the channel may not be neglected, i.e. if the slopes of the channel and free surface of the current are comparable, we find that, in a frame moving with speed Vf, the form of the governing equation for the height of a current in an equivalent horizontal channel is recovered. We calculate that the height of a constant flux gravity current down an inclined channel will tend to a fixed depth, which is determined by the channel shape, n, and the physical properties of the fluid and rock. Experimental and numerical results for inclined V-shaped channels agree very well with this theory.
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Mohd Yusof, Muhammad Azizol, Suraya Sharil, and Wan Hanna Melini Wan Mohtar. "THE HYDRODYNAMIC CHARACTERISTICS FOR VEGETATIVE CHANNEL WITH GRAVEL BED DUNES." Jurnal Teknologi 84, no. 2 (January 27, 2022): 93–102. http://dx.doi.org/10.11113/jurnalteknologi.v84.17045.
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Aquatic plants are known to provide flow resistance and impact the turbulence intensity and turbulent kinetic energy within the vegetated area. This paper further investigates the impact of both vegetation and dunes in open channels to the hydrodynamic characteristic of flow. Emergent vegetations were built from rigid wooden rod in staggered arrangement with 0.5% vegetations density were applied in the flume. Experiments were conducted with flow rate of 0.0058 m3/s throughout the experiments. Dunes were constructed from gravel of 2 mm size diameter in the shape of standing waves of three different lee slope angles of 3⁰, 6⁰ and 9⁰. Flow velocities are measured by using a velocimeter to get the raw data for the three-dimensional flow velocity in the x, y, and z directions. The velocities data were then analysed to calculate the mean velocity, turbulence intensity and turbulent kinetic energy. Experimental results showed that, for all three lee slope angles presented higher flow velocity in the vegetated channel compared to the non-vegetated channel. It was also found that greater lee slope angle dunes generate higher velocity for both channels with and without vegetation. Higher turbulence intensity can be found near the bed area and greater turbulence intensity also shown in the positive slope of a dunes compared to negative slope area. Higher turbulent kinetic energy values were recorded within the vegetated channel compared to the non-vegetated channels.
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Hansen, Bogi, Turið Poulsen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, Svein Østerhus, Elin Darelius, Barbara Berx, Detlef Quadfasel, and Kerstin Jochumsen. "Atlantic water flow through the Faroese Channels." Ocean Science 13, no. 6 (November 13, 2017): 873–88. http://dx.doi.org/10.5194/os-13-873-2017.
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Abstract. Through the Faroese Channels – the collective name for a system of channels linking the Faroe–Shetland Channel, Wyville Thomson Basin, and Faroe Bank Channel – there is a deep flow of cold waters from Arctic regions that exit the system as overflow through the Faroe Bank Channel and across the Wyville Thomson Ridge. The upper layers, in contrast, are dominated by warm, saline water masses from the southwest, termed Atlantic water. In spite of intensive research over more than a century, there are still open questions on the passage of these waters through the system with conflicting views in recent literature. Of special note is the suggestion that there is a flow of Atlantic water from the Faroe–Shetland Channel through the Faroe Bank Channel, which circles the Faroes over the slope region in a clockwise direction. Here, we combine the observational evidence from ship-borne hydrography, moored current measurements, surface drifter tracks, and satellite altimetry to address these questions and propose a general scheme for the Atlantic water flow through this channel system. We find no evidence for a continuous flow of Atlantic water from the Faroe–Shetland Channel to the Faroe Bank Channel over the Faroese slope. Rather, the southwestward-flowing water over the Faroese slope of the Faroe–Shetland Channel is totally recirculated within the combined area of the Faroe–Shetland Channel and Wyville Thomson Basin, except possibly for a small release in the form of eddies. This does not exclude a possible westward flow over the southern tip of the Faroe Shelf, but even including that, we estimate that the average volume transport of a Circum-Faroe Current does not exceed 0.5 Sv (1 Sv = 106 m3 s−1). Also, there seems to be a persistent flow of Atlantic water from the western part of the Faroe Bank Channel into the Faroe–Shetland Channel that joins the Slope Current over the Scottish slope. These conclusions will affect potential impacts from offshore activities in the region and they imply that recently published observational estimates of the transport of warm water towards the Arctic obtained by different methods are incompatible.
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Faug, Thierry, Mohamed Naaim, and Florence Naaim-Bouvet. "Experimental and numerical study of granular flow and fence interaction." Annals of Glaciology 38 (2004): 135–38. http://dx.doi.org/10.3189/172756404781814870.
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AbstractDense snow avalanches are regarded as dry granular flows. This paper presents experimental and numerical modelling of deposition processes occurring when a gravity-driven granular flow meets a fence. A specific experimental device was set up, and a numerical model based on shallow-water theory and including a deposition model was used. Both tools were used to quantify how the retained volume upstream of the fence is influenced by the channel inclination and the obstacle height. We identified two regimes depending on the slope angle. In the slope-angle range where a steady flow is possible, the retained volume has two contributions: deposition along the channel due to the roughness of the bed and deposition due to the fence. The retained volume results only from the fence effects for higher slopes. The effects of slope on the retained volume also showed these two regimes. For low slopes, the retained volume decreases strongly with increasing slope. For higher slopes, the retained volume decreases weakly with increasing slope. Comparison between the experiments and computed data showed good agreement concerning the effect of fence height on the retained volume.
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Gao, Zhenran, Weijing Li, Yan Zhu, Yongchao Tian, Fangrong Pang, Weixing Cao, and Jun Ni. "Wireless Channel Propagation Characteristics and Modeling Research in Rice Field Sensor Networks." Sensors 18, no. 9 (September 15, 2018): 3116. http://dx.doi.org/10.3390/s18093116.
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Wireless channel propagation characteristics and models are important to ensure the communication quality of wireless sensor networks in agriculture. Wireless channel attenuation experiments were carried out at different node antenna heights (0.8 m, 1.2 m, 1.6 m, and 2.0 m) in the tillering, jointing, and grain filling stages of rice fields. We studied the path loss variation trends at different transmission distances and analyzed the differences between estimated values and measured values of path loss in a free space model and a two-ray model. Regression analysis of measured path loss values was used to establish a one-slope log-distance model and propose a modified two-slope log-distance model. The attenuation speed in wireless channel propagation in rice fields intensified with rice developmental stage and the transmission range had monotone increases with changes in antenna height. The relative error (RE) of estimation in the free space model and the two-ray model under four heights ranged from 6.48–15.49% and 2.09–13.51%, respectively, and these two models were inadequate for estimating wireless channel path loss in rice fields. The ranges of estimated RE for the one-slope and modified two-slope log-distance models during the three rice developmental stages were 2.40–2.25% and 1.89–1.31%, respectively. The one-slope and modified two-slope log-distance model had better applicability for modeling of wireless channels in rice fields. The estimated RE values for the modified two-slope log-distance model were all less than 2%, which improved the performance of the one-slope log-distance model. This validates that the modified two-slope log-distance model had better applicability in a rice field environment than the other models. These data provide a basis for modeling of sensor network channels and construction of wireless sensor networks in rice fields. Our results will aid in the design of effective rice field WSNs and increase the transmission quality in rice field sensor networks.
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Mua, Kang Edwin, and Kometa Sunday Shende. "The Response of Stream Competence to Topographic and Seasonal Variations in The Bamenda-Menchum Drainage Basin, North West Region, Cameroon." Journal of Geography and Geology 11, no. 2 (May 30, 2019): 21. http://dx.doi.org/10.5539/jgg.v11n2p21.
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The flow direction of streams remains an establishing mechanism in understanding drainage basin function and stream competence. The ability of streams to erode, transport and deposit loads in fluvial geomorphology exert a benchmark precursor for slope dynamics given the differential geological outcrop of the Bamenda-Menchum basin. Such competence in stream network generates slope instability as materials continuously move down slope from the volcanic escarpment face of Bamenda highlands to the sedimentary lowland area of Lower Bafut-Menchum basin. This paper investigate the influence of stream flow direction and stream competence on slope dynamics and how such dynamism affects the development prospects of the drainage basin. Slope range was obtained from AVL/EBI.JHO measurement. Stream length, density and flow direction were gotten from GIS Arc 21. Stream depth, channel width, flow rate and sedimentation levels were measured. Gully depth on slopes and landslide angles were measured using 30m tape and a graduated pole. Questionnaires were used to collect information on the vulnerability of households to slope dynamics orchestrated by stream competence. Findings revealed that stream competence varies from the two geological basements and that the escarpment face respond to high flow gravity and hydraulic action contributing to rapid erosion and transportation of loads. The results equally showed that the Bamenda escarpment face that is linked to the crystalline rocks produce differential erosion and landslide. 76.7% of slope instability is explained by geological structure and seasonality effect in the basin while 23.3% of slope dynamics is explained by other variables not specified in the study. The lower basin remains liable to deposition of materials on river channels and flood plain. The accumulation of sand, stones and alluvial deposits are extracted and exploited for the development prospects of the basin. The study recommends channel and slope management by integrating slope development control policy in drainage basin management and development.
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Zhang, Yu, Fei Yu, Shan Xiong Chen, Xiao Jie Chu, and Zhang Jun Dai. "A Study on the Settlement Character of High Fill Channels." Applied Mechanics and Materials 513-517 (February 2014): 2639–42. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.2639.
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The settlement of high fill channels has great influence on the structural stability of the impervious panels in the North Water Diversion Project. For the high fill channels, the settlement study on the filling body and water channel slope of the channels after the completion of the filling is systematically carried out. The study result shows that the post-settlement development law of the channels accord with the hyperbolic, the settlement of the slope is uneven, and the deformation and the deformation rate of the slope is mainly controlled by vertical settling.
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Edwards, Chris, Sean McQuaid, Stewart Easton, Don Scott, Andrew Couch, Ron Evans, and Stephen Hart. "Lateral accretion in a straight slope channel system: an example from the Forties Sandstone of the Huntington Field, UK Central North Sea." Geological Society, London, Petroleum Geology Conference series 8, no. 1 (January 16, 2017): 413–28. http://dx.doi.org/10.1144/pgc8.33.
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AbstractA rich dataset of core, well logs and 3D seismic data has been integrated to establish a depositional hierarchy of a Paleocene-aged, Forties slope channel system of the Huntington Field, Block 22/14b of the Central North Sea. The reservoir consists of a mix of high-concentration turbidites and muddy and sandy debrites deposited as a series of laterally offset, slope channel fills. Seismic data reveal that the channels were remarkably straight and devoid of meander bends, more commonly associated with sinuous slope channel networks. Paradoxically, the internal offlapping architecture draws close comparisons with lateral accretion packages that are widely accepted to be the products of secondary flow circulation around sinuous channel bends. The straight nature of the Huntington channels precludes such an interpretation but can be explained as a consequence of Coriolis effects acting upon suspension-dominated flows in Northern Hemisphere high latitudes, resulting in the preferential accretion of sediment along the right-hand bank (when viewed downstream) and leading to the eventual lateral avulsion of the channel. The observed architecture has been incorporated into a reservoir model in order to characterize the static connectivity of the field that will in turn serve as a basis for understanding production behaviour.
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Zhang, Li, Tiejian Li, Guangqian Wang, Jeffrey S. Kwang, Jeffrey A. Nittrouer, Xudong Fu, and Gary Parker. "How canyons evolve by incision into bedrock: Rainbow Canyon, Death Valley National Park, United States." Proceedings of the National Academy of Sciences 117, no. 26 (June 15, 2020): 14730–37. http://dx.doi.org/10.1073/pnas.1911040117.
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Incising rivers may be confined by low-slope, erodible hillslopes or steep, resistant sidewalls. In the latter case, the system forms a canyon. We present a morphodynamic model that includes the essential elements of a canyon incising into a plateau, including 1) abrasion-driven channel incision, 2) migration of a canyon-head knickpoint, 3) sediment feed from an alluvial channel upstream of the knickpoint, and 4) production of sediment by sidewall collapse. We calculate incision in terms of collision of clasts with the bed. We calculate knickpoint migration using a moving-boundary formulation that allows a slope discontinuity where the channel head meets an alluvial plateau feeder channel. Rather than modeling sidewall collapse events, we model long-term behavior using a constant sidewall slope as the channel incises. Our morphodynamic model specifically applies to canyon, rather than river–hillslope evolution. We implement it for Rainbow Canyon, CA. Salient results are as follows: 1) Sediment supply from collapsing canyon sidewalls can be substantially larger than that supplied from the feeder channel on the plateau. 2) For any given quasi-equilibrium canyon bedrock slope, two conjugate slopes are possible for the alluvial channel upstream, with the lower of the two corresponding to a substantially lower knickpoint migration rate and higher preservation potential. 3) Knickpoint migration occurs at a substantially faster time scale than regrading of the bedrock channel itself, underlying the significance of disequilibrium processes. Although implemented for constant climactic conditions, the model warrants extension to long-term climate variation.
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Wallert, M. A., M. J. Ackerman, D. Kim, and D. E. Clapham. "Two novel cardiac atrial K+ channels, IK.AA and IK.PC." Journal of General Physiology 98, no. 5 (November 1, 1991): 921–39. http://dx.doi.org/10.1085/jgp.98.5.921.
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Two K(+)-selective channels in neonatal rat atrial cells activated by lipophilic compounds have been characterized in detail. The arachidonic acid-stimulated channel (IK.AA) had a slope conductance of 124 +/- 17 pS at +30 mV in symmetrical 140 mM potassium and a mean open time of approximately 1 ms, and was relatively voltage independent. IK.AA activity was reversibly increased by lowering pH to 6.0. Arachidonic acid was most effective in activating this channel, although a number of lipophilic compounds resulted in activation. Surprisingly, choline, a polar molecule, also activated the channel. A second K+ channel was activated by 10 microM phosphatidylcholine applied to the intracellular surface of inside-out atrial patches. This channel (IK.PC) had a slope conductance of 60 +/- 6 pS at +40 mV and a mean open time of approximately 0.6 ms, and was also relatively voltage independent. Fatty acids are probably monomeric in the membrane under the conditions of our recording; thus detergent effects are unlikely. Since a number of compounds including fatty acids and prostaglandins activated these two channels, an indirect, channel-specific mechanism may account for activation of these two cardiac K+ channels.
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Waltham, D. "Slope Control on Submarine Channel Widths." Journal of Sedimentary Research 78, no. 5 (May 1, 2008): 317–22. http://dx.doi.org/10.2110/jsr.2008.036.
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Jarosch, A. H., and M. T. Gudmundsson. "A numerical model for meltwater channel evolution in glaciers." Cryosphere Discussions 5, no. 5 (October 11, 2011): 2605–28. http://dx.doi.org/10.5194/tcd-5-2605-2011.
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Abstract. Meltwater channels form an integral part of the hydrological system of a glacier. Better understanding of how meltwater channels develop and evolve is required to fully comprehend supraglacial and englacial meltwater drainage. Incision of supraglacial stream channels and subsequent roof closure by ice deformation has been proposed in recent literature as a possible englacial conduit formation process. Field evidence for supraglacial stream incision has been found in Svalbard and Nepal. In Iceland, where volcanic activity provides meltwater with temperatures above 0 °C, rapid enlargement of supraglacial channels has been observed. By coupling, for the first time, a numerical ice dynamic model to a hydraulic model which includes heat transfer, we investigate the evolution of meltwater channels and their incision behaviour. We present results for different, constant meltwater fluxes, different channel slopes, different meltwater temperatures as well as temporal variations in meltwater flux. The key parameters governing incision rate and depth are the channel slope and the meltwater temperature loss to the ice. Meltwater flux controls channel width and to a lesser degree incision behaviour. Calculated Nusselt numbers suggest that turbulent forced convection is the main heat transfer mechanism in the studied meltwater channels.
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Hu, Qingfeng, Yingchao Kou, Jinping Liu, Wenkai Liu, Jiuyuan Yang, Shiming Li, Peipei He, et al. "TerraSAR-X and GNSS Data for Deformation Detection and Mechanism Analysis of a Deep Excavation Channel Section of the China South–North Water-Diversion Project." Remote Sensing 15, no. 15 (July 29, 2023): 3777. http://dx.doi.org/10.3390/rs15153777.
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Due to expansive soils and high slopes, the deep excavated channel section of the China South–North Water-Diversion Middle-Route Project has a certain risk of landslide disaster. Therefore, examining the deformation law and mechanism of the channel slope in the middle-route section of the project is an extreme necessity for safe operation. However, the outdated monitoring method limits research on the surface deformation law and mechanism of the entire deep excavation channel section. For these reasons, we introduced a novel approach that combines SBAS-InSAR and GNSS, enabling the surface domain monitoring of the study area at a regional scale as well as real-time monitoring of specific target regions. By using SBAS-InSAR technology and leveraging 11-view high-resolution TerraSAR-X data, we revealed the spatiotemporal evolution law of surface deformations in the channel slopes within the study area. The results demonstrate that the predominant deformation in the study area was uplifted, with limited evidence of subsidence deformation. Moreover, there is a distinct region of significant uplift deformation, with the highest annual uplift rate reaching 19 mm/y. Incorporating GNSS and soil-moisture-monitoring timeseries data, we conducted a study on the correlation between soil moisture and the three-dimensional deformation of the ground surface, revealing a positive correlation between the soil moisture content and vertical displacement of the channel slope. Furthermore, combining field investigations on surface uplift deformation characteristics, we identified that the main cause of surface deformation in the study area was attributed to the expansion of the soil due to water absorption in expansive soils. The research results not only revealed the spatiotemporal evolution law and mechanism of the channel slope deformation in the studied section of the deep excavation channel but also provide successful guidance for the prevention and control of channel slope-deformation disasters in the study area. Furthermore, they offer effective technical means for the safe monitoring of the entire South–North Water-Diversion Middle-Route Project and similar long-distance water-conveyance canal projects.
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Yao, Hongyun, Guanlin Song, and Yibo Li. "Displacement Prediction of Channel Slope Based on EEMD-IESSA-LSSVM Combined Algorithm." Applied Sciences 13, no. 17 (August 24, 2023): 9582. http://dx.doi.org/10.3390/app13179582.
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Slope displacement is a crucial factor that affects slope stability in engineering construction. The monitoring and prediction of slope displacement are especially important to ensure slope stability. To achieve this goal, it is necessary to establish an effective prediction model and analyze the patterns and trends of slope displacement. In recent years, monitoring efforts for high slopes have increased. With the growing availability of means and data for slope monitoring, the accurate prediction of slope displacement accidents has become even more critical. However, the lack of an accurate and efficient algorithm has resulted in an underutilization of available data. In this paper, we propose a combined EEMD-IESSA-LSSVM algorithm. Firstly, we use EEMD to decompose the slope displacement data and then introduce a more efficient and improved version of the sparrow search algorithm, called the irrational escape sparrow search algorithm (IESSA), by optimizing it and incorporating adaptive weight factors. We compare the IESSA algorithm with SSA, CSSOA, PSO, and GWO algorithms through validation using three different sets of benchmark functions. This comparison demonstrates that the IESSA algorithm achieves higher accuracy and a faster solving speed in solving these functions. Finally, we optimize LSSVM to predict slope displacement by incorporating rainfall and water level data. To verify the reliability of the algorithm, we conduct simulation analysis using slope data from the xtGTX1 monitoring point and the xtGTX3 monitoring point in the Yangtze River Xin Tan landslide and compare the results with those obtained using EEMD-LSSVM, EEMD-SSA-LSSVM, and EEMD-GWO-LSSVM. After numerical simulation, the goodness-of-fit of the two monitoring points is 0.98998 and 0.97714, respectively, which is 42% and 34% better than before. Using Friedman and Nemenyi tests, the algorithms were ranked as follows: IESSA-LSSVM > GWO-LSSVM > SSA-LSSVM > LSSVM. The findings indicate that the combined EEMD-IESSA-LSSVM algorithm exhibits a superior prediction ability and provides more accurate predictions for slope landslides compared to other algorithms.
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Barnes, S., and B. Hille. "Veratridine modifies open sodium channels." Journal of General Physiology 91, no. 3 (March 1, 1988): 421–43. http://dx.doi.org/10.1085/jgp.91.3.421.
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The state dependence of Na channel modification by the alkaloid neurotoxin veratridine was investigated with single-channel and whole-cell voltage-clamp recording in neuroblastoma cells. Several tests of whole-cell Na current behavior in the presence of veratridine supported the hypothesis that Na channels must be open in order to undergo modification by the neurotoxin. Modification was use dependent and required depolarizing pulses, the voltage dependence of production of modified channels was similar to that of normal current activation, and prepulses that caused inactivation of normal current had a parallel effect on the generation of modified current. This hypothesis was then examined directly at the single-channel level. Modified channel openings were easily distinguished from normal openings by their smaller current amplitude and longer burst times. The modification event was often seen as a sudden, dramatic reduction of current through an open Na channel and produced a somewhat flickery channel event having a mean lifetime of 1.6 s at an estimated absolute membrane potential of -45 mV (23 degrees C). The modified channel had a slope conductance of 4 pS, which was 20-25% the size of the slope conductance of normal channels with the 300 mM NaCl pipette solution used. Most modified channel openings were initiated by depolarizing pulses, began within the first 10 ms of the depolarizing step, and were closely associated with the prior opening of single normal Na channels, which supports the hypothesis that modification occurs from the normal open state.
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Tofelde, Stefanie, Sara Savi, Andrew D. Wickert, Aaron Bufe, and Taylor F. Schildgen. "Alluvial channel response to environmental perturbations: fill-terrace formation and sediment-signal disruption." Earth Surface Dynamics 7, no. 2 (July 1, 2019): 609–31. http://dx.doi.org/10.5194/esurf-7-609-2019.
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Abstract. The sensitivity of fluvial systems to tectonic and climatic boundary conditions allows us to use the geomorphic and stratigraphic records as quantitative archives of past climatic and tectonic conditions. Thus, fluvial terraces that form on alluvial fans and floodplains as well as the rate of sediment export to oceanic and continental basins are commonly used to reconstruct paleoenvironments. However, we currently lack a systematic and quantitative understanding of the transient evolution of fluvial systems and their associated sediment storage and release in response to changes in base level, water input, and sediment input. Such knowledge is necessary to quantify past environmental change from terrace records or sedimentary deposits and to disentangle the multiple possible causes for terrace formation and sediment deposition. Here, we use a set of seven physical experiments to explore terrace formation and sediment export from a single, braided channel that is perturbed by changes in upstream water discharge or sediment supply, or through downstream base-level fall. Each perturbation differently affects (1) the geometry of terraces and channels, (2) the timing of terrace cutting, and (3) the transient response of sediment export from the basin. In general, an increase in water discharge leads to near-instantaneous channel incision across the entire fluvial system and consequent local terrace cutting, thus preserving the initial channel slope on terrace surfaces, and it also produces a transient increase in sediment export from the system. In contrast, a decreased upstream sediment-supply rate may result in longer lag times before terrace cutting, leading to terrace slopes that differ from the initial channel slope, and also lagged responses in sediment export. Finally, downstream base-level fall triggers the upstream propagation of a diffuse knickzone, forming terraces with upstream-decreasing ages. The slope of terraces triggered by base-level fall mimics that of the newly adjusted active channel, whereas slopes of terraces triggered by a decrease in upstream sediment discharge or an increase in upstream water discharge are steeper compared to the new equilibrium channel. By combining fill-terrace records with constraints on sediment export, we can distinguish among environmental perturbations that would otherwise remain unresolved when using just one of these records.
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Deguchi, Ichiro, Masanobu Ono, Toru Sawaragi, and Kiseong Bae. "Reduction of Shoaling of Navigation Channel Using Composite Channel Slope." PROCEEDINGS OF CIVIL ENGINEERING IN THE OCEAN 8 (1992): 457–62. http://dx.doi.org/10.2208/prooe.8.457.
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Kosaj, Rasool, Rafid S. Alboresha, and Sadeq O. Sulaiman. "Comparison Between Numerical Flow3d Software and Laboratory Data, For Sediment Incipient Motion." IOP Conference Series: Earth and Environmental Science 961, no. 1 (January 1, 2022): 012031. http://dx.doi.org/10.1088/1755-1315/961/1/012031.
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Abstract In this paper, the laboratory data were compared with computational fluid dynamics (CFD) Flow3D for predicting the beginning of sediment incipient motion in rigid boundary channel for two types of sands, irrigation, and sewer types, in rectangular flume (0.5*0.5)m cross-section. Tests were made for soil samples with different diameters, specific weights. The testing was performed in slopes ranging from 0.001-0.003 for irrigation types and 0.0025-0.025 for sewer types depending on the original parameter. The Flow-3D software has simulated the laboratory work using scouring models MPM and Nielsen. the relation between sediment incipient motion velocity, particle size, and channel bed slope was predicted. The results were relatively more than laboratory data for the MPM model, while grating convergence for Nielsen model, especially for small diameter sediment. Also, the laboratory results are more close to the results of Flow3D using the Nielsen model when the value of bed slope of the channel is greater, and vice versa when the slope decreases.
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Setiyadi, Setiyadi. "PEMROGRAMAN SLOPE MINIMUM DAN KONSENTRASI SEDIMEN MAKSIMUM SEBAGAI ALTERNATIF PENDIMENSIAN SALURAN." Jurnal Rekayasa Teknik Sipil dan Lingkungan - CENTECH 1, no. 1 (April 25, 2020): 54–65. http://dx.doi.org/10.33541/cen.v1i1.1431.
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ABSTRACT
Design of dimension channel can use Minimum Slope and Maximum Concentration Sediment method. Minimum Slope is slope of channel, where is condition it the energy of flow is minimum, so channel condition is stabile. Maximum Sediment Concentration is method of sediment transport capacity, resistant and optimum it. Two methods are to produce of the same dimension of channel.
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Yang, Tan Shu, Yang Qu Tan, and Cui Juan Luo. "Application of Pine Piles for Strengthening High Slope Channel Retaining Walls on Soft Soil Subgrade." Applied Mechanics and Materials 438-439 (October 2013): 1190–94. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.1190.
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In the modification of narrow deep soil channels of early urban excavation, because of great depth and steep slope, the gravity retaining wall slope will be needed. The problems of soft soil subgrade treatment at channel bottom have to be solved. Combined with the old channel treatment project of a city, as practical example, the method by which the soft subgrade of channel retaining walls strengthening with pine piles, is described. By application of Coulomb Theory, the stability calculation for gravity pitch-up oblique retaining walls is conducted. The results show that using pine piles is a good method for strengthening the soft soil subgrade with small thickness below the water level.
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Mei, Han, Hu Xiewen, and Hu Kai. "Comparative study between debris flow of wide-gentle and narrow-steep channel based on numerical simulation and prevention measures." Journal of Nepal Geological Society 55, no. 1 (June 4, 2018): 167–72. http://dx.doi.org/10.3126/jngs.v55i1.22808.
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Along the Duwen freeway in the Wenchuan earthquake area, there are two main types of debris flow channels, that is, wide-gentle channel and narrow-steep channel. The wide-gentle channel has the feature of gentle longitudinal slope, large mean width and catchment area. Whereas the narrow-steep one generally shows opposite features with narrow longitudinal slope, small mean width and catchment
area. During the heavy rainfall, these channels are subject to large-scale debris flows due to huge amount of earthquake-induced collapsing and sliding materials. With field investigation on the formation conditions and development characteristics in the Taoguan and the Mozi gullies, we analysed the resulting impact, burying and blockage to the Duwen freeway and the Minjiang River. The sediment characteristic in the above-mentioned types of debris flow gully was intensively studied. Finally, prevention measures of the debris flow and effectiveness analysis of the treatment were proposed based on the features of the two types of channels.
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Das, Prosenjit, Sudip K. Samanta, Himadri Chattaopadhyay, and Pradip Dutta. "Studies on Rheocasting Using Cooling Slope." Solid State Phenomena 192-193 (October 2012): 341–46. http://dx.doi.org/10.4028/www.scientific.net/ssp.192-193.341.
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In the present work, a cooling channel is employed to produce semi-solid A356 alloy slurry. To understand the transport process involved, a 3D non-isothermal, multiphase volume averaging model has been developed for simulation of the semi-solid slurry generation process in the cooling channel. For simulation purpose, the three phases considered are the parent melt, the nearly spherical grains and air as separated but highly coupled interpenetrating continua. The conservation equations of mass, momentum, energy and species have been solved for each phase and the thermal and mechanical interactions (drag force) among the phases have been considered using appropriate model. The superheated liquid alloy is poured at the top of the cooling slope/channel, where specified velocity inlet boundary condition is used in the model, and allowed to flow along gravity through the channel. The melt loses its superheat and becomes semisolid up to the end of cooling channel due to the evolving -Al grains with decreasing temperature. The air phase forms a definable air/liquid melt interface, i.e. free surface, due its low density. The results obtained from the present model includes volume fractions of three different phases considered, grain evolution, grain growth rate, size and distribution of solid grains. The effect of key process variables such as pouring temperature, slope angle of the cooling channel and cooling channel wall temperature on temperature distribution, velocity distribution, grain formation and volume fraction of different phases are also studied. The results obtained from the simulations are validated by microstructure study using SEM and quantitative image analysis of the semi-solid slurry microstructure obtained from the experimental set-up.
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Święchowicz, Jolanta. "The assessment of influence of soil erosion by water in the transformation of agricultural slopes of the Wiśnicz Foothills." Landform Analysis 36 (December 30, 2018): 85–95. http://dx.doi.org/10.12657/landfana.036.008.
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The main aim of the paper is to assess influence of soil erosion by water in the transformation of agricultural slopes of the edge of Wiśnicz Foothills. Low hills are typical in the morphology of the area. Results presented come from measurements of soil erosion by water in 2007–2009. Soil erosion took place during short transformation periods and was caused by events of high magnitude and low frequency during which soil particles are transported from the slope to the channel, but its supply was only local and episodic. In the foothill area slope and channel are weakly linked.
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Senjyu, Tomoharu. "Deep current structure in the Toyama Deep-Sea Channel in the Japan Sea." Journal of Oceanography 78, no. 1 (October 29, 2021): 25–34. http://dx.doi.org/10.1007/s10872-021-00622-5.
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AbstractThe flow field in the Toyama Deep-Sea Channel (TDSC) in the Japan Sea was investigated based on mooring observations. An asymmetric current system accompanying offshore and onshore currents over the east- and west-side slopes in the channel, respectively, is suggested. A bottom intensified flow characteristic was observed at the offshore stations in the Yamato Basin. The asymmetric current system in the channel is also suggested by the asymmetric distribution of water characteristics across the TDSC in Toyama Bay; a cold dense water mass with higher dissolved oxygen (DO) and higher transmittance (Tr) was found over the west-side slope of the channel, whereas a water mass with lower DO and lower Tr was distributed over the east-side slope, suggesting a turbidity current from the head of Toyama Bay. The currents facing the shallower depth on their right-hand-side, along with the density distribution in the TDSC, suggest a density current system under the influence of the earth’s rotation. The dissolved oxygen concentration in the TDSC was significantly lower than that in the offshore region of the same temperature range. This suggests that the water mass over the west-side slope in the TDSC is a modified offshore water mass which experienced significant mixing with the low DO water mass over the east-side slope in the TDSC, probably due to strong shear between the offshore and onshore currents in the narrow channel.
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Drijfhout, Sybren, and Leo R. M. Maas. "Impact of Channel Geometry and Rotation on the Trapping of Internal Tides." Journal of Physical Oceanography 37, no. 11 (November 1, 2007): 2740–63. http://dx.doi.org/10.1175/2007jpo3586.1.
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Abstract The generation and propagation of internal tides has been studied with an isopycnic three-dimensional ocean model. The response of a uniformly stratified sea in a channel, which is forced by a barotropic tide on its open boundary, is considered. The tide progresses into the channel and forces internal tides over a continental slope at the other end. The channel has a length of 1200 km and a width of 191.25 km. The bottom profile has been varied. In a series of four experiments it is shown how the cross-channel geometry affects the propagation and trapping of internal tides, and the penetration scale of wave energy, away from the continental slope, is discussed. In particular it is found that a cross-channel bottom slope constrains the penetration of the internal tidal energy. Most internal waves refract toward a cross-channel plane where they are trapped. The exception is formed by edge waves that carry part of the energy away from the continental slope. In the case of rotation near the continental slope, the Poincaré waves that arise in the absence of a cross-channel slope no longer bear the characteristics of the wave attractor predicted by 2D theory, but are almost completely arrested, while the right-bound Kelvin wave preserves the 2D attractor in the cross-channel plane, which is present in the nonrotating case. The reflected, barotropic right-bound Kelvin wave acts as a secondary internal wave generator along the cross-channel slope.
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Baar, Anne, Marcio Boechat Albernaz, Wout van Dijk, and Maarten Kleinhans. "The influence of transverse slope effects on large scale morphology in morphodynamic models." E3S Web of Conferences 40 (2018): 04021. http://dx.doi.org/10.1051/e3sconf/20184004021.
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Large-scale morphology is greatly affected by the amount of downslope sediment transport on slopes transverse to the main flow direction, which determines bar length and bifurcation dynamics. Consequently, the transverse slope parameter is a crucial part of morphodynamic models. However, existing models have the tendency to overpredict channel depth and braiding index, and therefore slope effects are often increased when calibrating on existing morphology. The objective of this study is to identify possible causes of the overdeepening of channels in the morphodynamic model Delft3D, and to show how different slope effect parameterisations affect morphology in rivers and estuaries. Results show that the two methods to calculate transverse sediment transport in Delft3D have a significantly different effect on the predicted morphology and this effect is larger for environments with a large braiding index, in combination with the sediment transport predictor of Engelund-Hansen. Results furthermore imply that even when models are initially calibrated on existing morphology, results could significantly differ downstream when calibrated with a different choice of transverse slope option.
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Jarosch, A. H., and M. T. Gudmundsson. "A numerical model for meltwater channel evolution in glaciers." Cryosphere 6, no. 2 (April 16, 2012): 493–503. http://dx.doi.org/10.5194/tc-6-493-2012.
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Abstract. Meltwater channels form an integral part of the hydrological system of a glacier. Better understanding of how meltwater channels develop and evolve is required to fully comprehend supraglacial and englacial meltwater drainage. Incision of supraglacial stream channels and subsequent roof closure by ice deformation has been proposed in recent literature as a possible englacial conduit formation process. Field evidence for supraglacial stream incision has been found in Svalbard and Nepal. In Iceland, where volcanic activity provides meltwater with temperatures above 0 °C, rapid enlargement of supraglacial channels has been observed. Supraglacial channels provide meltwater through englacial passages to the subglacial hydrological systems of big ice sheets, which in turn affects ice sheet motion and their contribution to eustatic sea level change. By coupling, for the first time, a numerical ice dynamic model to a hydraulic model which includes heat transfer, we investigate the evolution of meltwater channels and their incision behaviour. We present results for different, constant meltwater fluxes, different channel slopes, different meltwater temperatures, different melt rate distributions in the channel as well as temporal variations in meltwater flux. The key parameters governing incision rate and depth are channel slope, meltwater temperature loss to the ice and meltwater flux. Channel width and geometry are controlled by melt rate distribution along the channel wall. Calculated Nusselt numbers suggest that turbulent mixing is the main heat transfer mechanism in the meltwater channels studied.
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Yang, Xu Liang, Ri Chen Ji, Wen Wen Bai, and Xi Chen. "Steady Seepage Analysis of the Filled Channel Slope with Anisotropy." Advanced Materials Research 1033-1034 (October 2014): 411–15. http://dx.doi.org/10.4028/www.scientific.net/amr.1033-1034.411.
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Middle Route of South-to-North Water Transfer Project main canal is grand supplied channel, it has the high requirements for transfer water reliability, so seepage control is particularly important for the channel slope along canal. According to conditions of seepage field and transformed relations of permeability coefficient to respectively simulate the seepage of channel slope with the homogeneous isotropic seepage field and the homogeneous anisotropic seepage field, the mathematical model and finite element model were created for the seepage of the filled channel slope with stratified and rolled, using ANSYS thermal analysis module for steady seepage analysis. Compared analysis shows that the seepage of the stratified and rolled channel slope in homogeneous anisotropic of seepage field is more intense than in homogeneous isotropic of seepage field, the analysis of the stratified channel slope by the homogeneous anisotropic seepage field matches the actual and is also more reasonable.
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Al-Masgari, Abd Al-Salam, Mohamed Elsaadany, Numair A. Siddiqui, Abdul Halim Abdul Latiff, Azli Abubakar, Qazi Sohai Imran, Ismailalwali Babikir, Muhammad Khan, and Teslim Adeleke. "Potential stratigraphic traps delineation utilizing the spectral decomposition approach for RGB color blending attribute generation: a case study in the Malay Basin." IOP Conference Series: Earth and Environmental Science 1003, no. 1 (April 1, 2022): 012015. http://dx.doi.org/10.1088/1755-1315/1003/1/012015.
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Abstract Implementing the RGB color blending attribute of the decomposed spectral has been successfully conducted for delineating the potential stratigraphic traps within the geomorphological elements of the studied interval from -1253ms to -800ms. The investigated area is situated in the peninsular Malaysia-Malay Basin and covering two neighbouring fields (Inas and Melor). Several fluvial system deposits dominate the studied interval. These interval’s time slices maps reveal several geomorphological features such as low meandering and superimposed fluvial channels system. Moreover, several structural elements and seismic artefacts are also delineated within the depositional sequences (DS-01-02) of Inas and Melor fields. The channel's sinuosity degree reflects the slope ratio of the substratum during the river's lifetime along the channel pathways. However, the low sinuosity of the main channel reflects the higher slope of the bedrock, while the high sinuousness of channels implies a lower depositional substratum slope. Validation steps have been performed utilized the gamma-ray logs signatures from several wells.