scholarly journals Global analysis of the stream power law parameters based on worldwide 10Be denudation rates

Geomorphology ◽  
2016 ◽  
Vol 268 ◽  
pp. 184-196 ◽  
Author(s):  
M.-A. Harel ◽  
S.M. Mudd ◽  
M. Attal
Keyword(s):  
Power Law ◽  
Global Analysis ◽  
Stream Power ◽  
Denudation Rates ◽  
Power Law Parameters

scholarly journals METHODS OF CFD MODELLING OF TWIN-SCREW PUMPS FOR NON-NEWTONIAN MATERIALS

2021 ◽  
Vol 2021 (6) ◽  
pp. 5366-5372
Author(s):  
MARIAN BOJKO ◽  
◽  
LUKAS HERTL ◽  
SYLVA DRABKOVA ◽  
◽  
...  
Keyword(s):  
Power Law ◽  
Food Industry ◽  
3D Model ◽  
Design Parameters ◽  
Cfd Modelling ◽  
Ansys Fluent ◽  
Screw Pump ◽  
Twin Screw ◽  
Definition Of ◽  
Power Law Parameters

The twin-screw pump is designed for pumping highly viscous materials in the food industry. Rheological characteristics of materials are important in the specification of design parameters of screw pumps. Analysis of flow in the twin-screw pumps with definition of non-newtonian materials can be made by numerical modelling. CFD generally oriented software ANSYS Fluent and ANSYS Polyflow has been used for modelling. In this study those software’s (ANSYS Fluent and ANSYS Polyflow) were defined for solution of flow in the twin-screw pumps. Results were compared for the same boundary conditions on the inlet and outlet of the 3D model. For definition of the viscosity were used the Nonnewtonian power law. Parameters as consistency coefficient and flow exponent for Nonnewtonian power law were analysed by software ANSYS Fluent and ANSYS Polyflow. Postprocessing form ANSYS Fluent and ANSYS Polyflow were made by contours of field and by graphs.

Correlation analysis of the power law parameters for viscosity of some engineering fluids

2017 ◽  
pp. 1-9 ◽  
Author(s):  
R.B. Haj-Kacem ◽  
J.V. Herráez ◽  
A.A. Al-Arfaj ◽  
M.A. Alkhaldi ◽  
N.O. Alzamil ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Power Law ◽  
Power Law Parameters

Influence of epoxidation conditions on the rheological properties of gel-like dispersions of epoxidized kraft lignin in castor oil

Holzforschung ◽  
2017 ◽  
Vol 71 (10) ◽  
pp. 777-784 ◽  
Author(s):  
Esperanza Cortés-Triviño ◽  
Concepción Valencia ◽  
José M. Franco
Keyword(s):  
Power Law ◽  
Castor Oil ◽  
Complex Modulus ◽  
Softening Temperature ◽  
Gel Strength ◽  
Rheological Characterization ◽  
Scanning Calorimetry ◽  
Small Amplitude Oscillatory Shear ◽  
Power Law Equation ◽  
Power Law Parameters

Abstract The modification of castor oil (CO) with lignin was the focus of this research to create a lubricating medium with improved gel-like properties. Namely, an alkali lignin (L) was epoxidized with epichlorohydrin (EP) and the resulting LEPs were dispersed in CO. The parameters of LEP synthesis were varied and the epoxidation index (EPI) of the LEPs was determined. The LEPs were also submitted to thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Rheological responses of the LEP/CO dispersions were investigated through small-amplitude oscillatory shear (SAOS) tests. Linear viscoelasticity functions are quantitatively affected by the epoxidation parameters, such as temperature, reaction time and L/EP and L/NaOH ratios. In general, lignins with higher EPI show higher values of the SAOS functions, which are indicative of better gel-strength due to a higher cross-linking density between the LEPs and CO. A power-law equation describes well the evolution of the complex modulus, G*, with frequency of gel-like dispersions, where the power-law parameters were found to increase almost linearly with the EPI. The thermo-rheological characterization provides a softening temperature beyond 50°C.

scholarly journals Millennial-scale denudation rates in the Himalaya of Far Western Nepal

2019 ◽  
Author(s):  
Lujendra Ojha ◽  
Ken L. Ferrier ◽  
Tank Ojha
Keyword(s):  
Stream Power ◽  
Denudation Rate ◽  
The Past ◽  
Cosmogenic Nuclide ◽  
Northern India ◽  
Denudation Rates ◽  
Cosmogenic 10Be ◽  
Channel Steepness ◽  
The Himalaya ◽  
Millennial Scale

Abstract. Over the past two decades, rates and patterns of Himalayan denudation have been documented through numerous cosmogenic nuclide measurements in central and eastern Nepal, Bhutan, and northern India. To date, however, few denudation rates have been measured in Far Western Nepal – a ~ 300-km-wide region near the center of the Himalayan arc – which presents a significant gap in our understanding of Himalayan denudation. Here we report new catchment-averaged millennial-scale denudation rates inferred from cosmogenic 10Be in fluvial quartz at seven sites in Far Western Nepal. The inferred denudation rates range from 385 ± 31 t km−2 yr−1 (0.15 ± 0.01 mm yr −1) to 8737 ± 2908 t km−2 yr−1 (3.3 ± 1.1 mm yr−1), and, in combination with our analyses of channel topography, are broadly consistent with previously published relationships between catchment-averaged denudation rates and normalized channel steepness across the Himalaya. These data show a weak correlation with catchment-averaged specific stream power, consistent with a Himalaya-wide compilation of previously published stream power values. Together, these observations are consistent with a dependence of denudation rate on both tectonic and climatic forcings, and represent a first step toward filling an important gap in denudation rate measurements in Far Western Nepal.

scholarly journals Parameterization of river incision models requires accounting for environmental heterogeneity: insights from the tropical Andes

2020 ◽  
Vol 8 (2) ◽  
pp. 447-470 ◽  
Author(s):  
Benjamin Campforts ◽  
Veerle Vanacker ◽  
Frédéric Herman ◽  
Matthias Vanmaercke ◽  
Wolfgang Schwanghart ◽  
...  
Keyword(s):  
Spatial Patterns ◽  
Rainfall Variability ◽  
Nonlinear Relationship ◽  
Stream Power ◽  
Denudation Rates ◽  
River Incision ◽  
Power Models ◽  
Bedrock River Incision ◽  
Lithological Heterogeneity

Abstract. Landscape evolution models can be used to assess the impact of rainfall variability on bedrock river incision over millennial timescales. However, isolating the role of rainfall variability remains difficult in natural environments, in part because environmental controls on river incision such as lithological heterogeneity are poorly constrained. In this study, we explore spatial differences in the rate of bedrock river incision in the Ecuadorian Andes using three different stream power models. A pronounced rainfall gradient due to orographic precipitation and high lithological heterogeneity enable us to explore the relative roles of these controls. First, we use an area-based stream power model to scrutinize the role of lithological heterogeneity in river incision rates. We show that lithological heterogeneity is key to predicting the spatial patterns of incision rates. Accounting for lithological heterogeneity reveals a nonlinear relationship between river steepness, a proxy for river incision, and denudation rates derived from cosmogenic radionuclide (CRNs). Second, we explore this nonlinearity using runoff-based and stochastic-threshold stream power models, combined with a hydrological dataset, to calculate spatial and temporal runoff variability. Statistical modeling suggests that the nonlinear relationship between river steepness and denudation rates can be attributed to a spatial runoff gradient and incision thresholds. Our findings have two main implications for the overall interpretation of CRN-derived denudation rates and the use of river incision models: (i) applying sophisticated stream power models to explain denudation rates at the landscape scale is only relevant when accounting for the confounding role of environmental factors such as lithology, and (ii) spatial patterns in runoff due to orographic precipitation in combination with incision thresholds explain part of the nonlinearity between river steepness and CRN-derived denudation rates. Our methodology can be used as a framework to study the coupling between river incision, lithological heterogeneity and climate at regional to continental scales.

Evaluation of the Gradation Effect on the Dynamic Modulus

2005 ◽  
Vol 1929 (1) ◽  
pp. 193-199 ◽  
Author(s):  
Bjorn Birgisson ◽  
Reynaldo Roque
Keyword(s):  
Power Law ◽  
Dynamic Modulus ◽  
Asphalt Mixture ◽  
Design Procedure ◽  
Maximum Size ◽  
Pavement Design ◽  
Aggregate Gradation ◽  
Higher Temperature ◽  
Power Law Parameters ◽  
Selection Of

The importance of aggregate characteristics has been emphasized in the Superpave® asphalt mixture design procedure. However, criteria for guidelines for the selection of suitable aggregate gradations–-other than gradation limits for different nominal maximum size aggregate blends, including the restricted zone–-have been neglected. With the move toward mechanistic–empirical pavement design, the dynamic modulus is used to account for mixture properties in the pavement design. It is of significant importance to mix designers to possess a framework for determining how to optimize a mixture for ensuring an adequate dynamic modulus. This paper presents the results from a study of the effects of gradation characteristics on the dynamic modulus. Power law–based gradation factors are obtained for 13 aggregate gradations (coarse and fine graded) composed of limestone and granite aggregates. These gradation factors were used to identify and evaluate relationships between gradation factors and the dynamic modulus at higher temperature (40°C). Subsequently, a tentative framework was established for optimizing mixture gradations for dynamic modulus values. Findings illustrate that gradation factors based on power law parameters can be used to optimize mixture gradations for key mixture properties, such as the dynamic modulus. Results also demonstrate the critical nature of aggregate gradation in achieving desired mixture properties.

scholarly journals On different types of adjustment usable to calculate the parameters of the stream power law

Geomorphology ◽  
2012 ◽  
Vol 138 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Alain Demoulin ◽  
Arnaud Beckers ◽  
Benoît Bovy
Keyword(s):  
Power Law ◽  
Stream Power ◽  
Different Types
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