Time variation of scour depth around complex abutment

2014 ◽  
pp. 455-460 ◽  
Author(s):  
R Mohammadpour ◽  
A Ghani ◽  
N Zakaria
Keyword(s):  
Time Variation ◽  
Scour Depth

scholarly journals Prediction of time variation of scour depth around spur dikes using neural networks

2011 ◽  
Vol 14 (1) ◽  
pp. 180-191 ◽  
Author(s):  
Hojat Karami ◽  
Abdollah Ardeshir ◽  
Mojtaba Saneie ◽  
S. Amin Salamatian
Keyword(s):  
Neural Networks ◽  
Regression Model ◽  
Time Variation ◽  
Back Propagation ◽  
Maximum Depth ◽  
Scour Depth ◽  
Effective Parameters ◽  
Spur Dike ◽  
Feed Forward Back Propagation ◽  
Spur Dikes

The maximum depth of scouring around spur dikes plays an important role in the hydraulic design process. There have been many studies on the maximum depth of scouring, but there is little information available on the time variation of scour depth. In this paper, the time variation of scouring around the first spur dike in a series was investigated experimentally. Experiments were carried out in four different bed materials under different flow intensities (U/Ucr). To achieve a time development of scouring around the first spur dike, more than 750 sets of experimental data were collected. The results showed that 70–90% of the equilibrium scour depths were occurring during the initial 20% of the overall time of scouring. Based on the data analysis, a regression model and artificial neural networks (ANNs) were developed. The models were compared with other empirical equations in the literature. However, the results showed that the developed regression model is quite accurate and more practical, but the ANN models by feed forward back propagation and radial basis function provide a better prediction of observation. Finally, by sensitivity analysis, the most and the least effective parameters, which affected time variation of scouring, were determined.

Improvement in Computational Accuracy of Output Transition Time Variation Considering Threshold Voltage Variations

2009 ◽  
Vol E92-A (4) ◽  
pp. 990-997
Author(s):  
Takaaki OKUMURA ◽  
Atsushi KUROKAWA ◽  
Hiroo MASUDA ◽  
Toshiki KANAMOTO ◽  
Masanori HASHIMOTO ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Time Variation ◽  
Transition Time ◽  
Computational Accuracy

A striped pattern of snowfall and snow cover

1993 ◽  
Vol 18 ◽  
pp. 27-32
Author(s):  
Yasuaki Nohguchi ◽  
Takashi Ikarashi ◽  
Osamu Abe ◽  
Atsushi Sato
Keyword(s):  
Snow Cover ◽  
Atmospheric Turbulence ◽  
Layered Structure ◽  
Time Variation ◽  
Vertical Wall ◽  
Striped Pattern

A striped pattern can be seen by spraying ink on a vertical wall of a snow pit to observe the layered structure of a snow cover. This pattern is caused by variations of snowfall in time, particularly pauses in snowfall, and its structure is related to a kind of fractal. In this paper, we consider snowfall and snow cover from a viewpoint of fractals and show that the layered structure of snow cover is a record of fractals on atmospheric-turbulence phenomena through the time variation of snowfall.

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