scholarly journals Case Study on the Estimation Accuracy of the Parameters of a Rock Physical Model

2016 ◽  
Author(s):  
Anett Kiss
Keyword(s):  
Physical Model ◽  
Estimation Accuracy ◽  
Rock Physical Model

A Review on Enhanced Stability Analyses of Soil Slopes Using Statistical Design

2018 ◽  
pp. 446-481
Author(s):  
Srđan Kostić
Keyword(s):  
Slope Stability ◽  
External Validation ◽  
Statistical Design ◽  
Estimation Accuracy ◽  
Rupture Surface ◽  
Stability Of Slopes ◽  
Mathematical Expressions ◽  
Grid Search Method ◽  
Homogeneous Soil

This chapter deals with the application of experimental design in slope stability analysis. In particular, focus of the present chapter is on the application of Box-Behnken statistical design for assessment of stability of slopes in homogeneous soil (general case), for estimation of slope stability in clay-marl deposits at the edge of Neogene basins (case study) and for the extension of grid search method for locating the critical rupture surface. Extensive statistical analysis, internal and external validation imply high estimation accuracy and reliability of developed mathematical expressions for slope safety factor and for parameters of location of critical rupture surface. Main advantages and limitations of the proposed approach are thoroughly discussed with suggestions for main directions of further research.

scholarly journals Estimating Fire Background Temperature at a Geostationary Scale—An Evaluation of Contextual Methods for AHI-8

2018 ◽  
Vol 10 (9) ◽  
pp. 1368 ◽  
Author(s):  
Bryan Hally ◽  
Luke Wallace ◽  
Karin Reinke ◽  
Simon Jones ◽  
Chermelle Engel ◽  
...  
Keyword(s):  
Contextual Information ◽  
Window Size ◽  
Fire Detection ◽  
Estimation Accuracy ◽  
Significant Deterioration ◽  
Temperature Estimation ◽  
Landscape Characteristics ◽  
Detection And Attribution ◽  
Background Temperature

An integral part of any remotely sensed fire detection and attribution method is an estimation of the target pixel’s background temperature. This temperature cannot be measured directly independent of fire radiation, so indirect methods must be used to create an estimate of this background value. The most commonly used method of background temperature estimation is through derivation from the surrounding obscuration-free pixels available in the same image, in a contextual estimation process. This method of contextual estimation performs well in cloud-free conditions and in areas with homogeneous landscape characteristics, but increasingly complex sets of rules are required when contextual coverage is not optimal. The effects of alterations to the search radius and sample size on the accuracy of contextually derived brightness temperature are heretofore unexplored. This study makes use of imagery from the AHI-8 geostationary satellite to examine contextual estimators for deriving background temperature, at a range of contextual window sizes and percentages of valid contextual information. Results show that while contextual estimation provides accurate temperatures for pixels with no contextual obscuration, significant deterioration of results occurs when even a small portion of the target pixel’s surroundings are obscured. To maintain the temperature estimation accuracy, the use of no less than 65% of a target pixel’s total contextual coverage is recommended. The study also examines the use of expanding window sizes and their effect on temperature estimation. Results show that the accuracy of temperature estimation decreases significantly when expanding the examined window, with a 50% increase in temperature variability when using a larger window size than 5 × 5 pixels, whilst generally providing limited gains in the total number of temperature estimates (between 0.4%–4.4% of all pixels examined). The work also presents a number of case study regions taken from the AHI-8 disk in more depth, and examines the causes of excess temperature variation over a range of topographic and land cover conditions.

scholarly journals The Effects of Hydraulic Jumps Instability on a Natural River Confluence: The Case Study of the Chiaravagna River (Italy)

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2027 ◽  
Author(s):  
Annalisa De Leo ◽  
Alessia Ruffini ◽  
Matteo Postacchini ◽  
Marco Colombini ◽  
Alessandro Stocchino
Keyword(s):  
Physical Model ◽  
Hydraulic Jump ◽  
Low Frequency ◽  
Water Levels ◽  
Entire Area ◽  
Hydraulic Conditions ◽  
River Confluence ◽  
Series Of Experiments ◽  
Small River Basin

The occurrence and the effects of hydraulic jump instabilities on a natural river confluence in a small river basin in Liguria (Italy) is here investigated. Hydraulic jump instability has been extensively studied in controlled and simplified laboratory rectangular flumes. In the present study, a scaled physical model of the Chiaravagna River and Ruscarolo Creek confluence has been used, retaining the realistic geometry of the reaches. This reach has been subject to frequent floods in the last twenty years and the entire area of the confluence has been redesigned to decrease the flood risk. A series of experiments has been performed varying the discharge on the two reaches and the geometrical configurations. Free surface levels and two dimensional horizontal velocities have been measured in several positions along the physical model. The analysis of the water levels and velocities reveals that oscillations characterised by large amplitude and low frequency occur under particular hydraulic conditions. These oscillations have been found to be triggered by the hydraulic jump toe instability of the smallest reach of the confluence. Aiming at reducing the amplitude of the oscillations, which can be of the order of the flow depth, possible constructive solutions have been tested to control or damp the oscillations. Indeed, the insertion of a longitudinal dyke at the confluence has proven to be an effective solution to limit the amplitude of the transversal oscillations.

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