scholarly journals Application of neuro-fuzzy model to estimate the characteristics of local scour downstream of stilling basins

2009 ◽  
Vol 12 (2) ◽  
pp. 201-211 ◽  
Author(s):  
J. Farhoudi ◽  
S. M. Hosseini ◽  
M. Sedghi-Asl
Keyword(s):  
Fuzzy Model ◽  
Local Scour ◽  
Bridge Piers ◽  
Type I ◽  
Effective Parameters ◽  
Promising Alternative ◽  
Neuro Fuzzy ◽  
Scour Hole ◽  
Stilling Basins ◽  
Tail Water

The local scour phenomenon in the vicinity of bridge piers and stilling basins has received considerable attraction from designers due to its consequences which may endanger these structures. Various factors govern the pattern of scour evolution which results in the complexity of this phenomenon. Many researchers indicated that the use of fuzzy logic in modeling this phenomenon could be a promising alternative to reflect the vagueness and ambiguity of effective parameters. The aim of this study is to investigate the performance of a neuro-fuzzy model based on Takagi and Sugeno's theory in estimating the maximum depths, pattern and time evolution of scour hole downstream of a stilling basin of U.S.B.R. type I. The investigation was conducted under various discharges, tail-water depths (low, balanced and high), different bed materials and model sizes. The characteristics of the equilibrium state of the scour phenomenon as well as the time to reach the maximum scour depth were considered. The results showed a significant conformity between estimated and experimental data which recommends an acceptable outcome using a neuro-fuzzy model to forecast the properties of scour hole downstream of stilling basins. This would contribute to predicting the design geometry of stilling pools and taking the appropriate precautions to protect the downstream channel bed.

Erosion of unconsolidated gravel beds

1985 ◽  
Vol 12 (3) ◽  
pp. 559-566 ◽  
Author(s):  
S. P. Chee ◽  
E. M. Yuen
Keyword(s):  
Analytical Study ◽  
Local Scour ◽  
Hydraulic Control ◽  
Control Structures ◽  
Gravel Beds ◽  
Water Jets ◽  
River Bed ◽  
Motion Condition ◽  
Scour Hole ◽  
Tail Water

In any riverbed degradation phenomenon, the vertical dimension of the deepest part of the scour hole is a pertinent parameter since all the other erosion parameters describing the configuration of the scour hole depend on its numerical value. Hence, it is necessary to be able to evaluate the maximum depth of the scour hole.For most practical situations, the impingement of submerged water jets on a granular riverbed occurs at an angle, and it is the object of this study to include the effects of obliqueness in the analysis. Some examples of the effects of impingement by water jets are the erosion problems caused by plunging water jets from hydraulic control structures as they discharge into the tail-water downstream.Basic to an understanding of the mechanism of local scour is the concept of "initiation of motion." Hence, the analytical study will use this concept to derive generalized relations that will link the incipient motion condition at the deepest point of the scour hole with the numerical value of the scoured depth. In addition, care was taken to ensure that only those hydraulic variables that are frequently used in hydraulic engineering design are included in the analysis in order to make the results useful to practicing engineers. Key words: local scour, maximum erosion, river bed, plunge basin, diving jets, energy dissipation, riverbed degradation.

CFD prediction of local scour hole around bridge piers

2012 ◽  
Vol 19 (1) ◽  
pp. 273-281 ◽  
Author(s):  
Zhi-wen Zhu ◽  
Zhen-qing Liu
Keyword(s):  
Local Scour ◽  
Bridge Piers ◽  
Scour Hole

scholarly journals Improving the 2D Numerical Simulations on Local Scour Hole around Spur Dikes

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1462
Author(s):  
Chung-Ta Liao ◽  
Keh-Chia Yeh ◽  
Yin-Chi Lan ◽  
Ren-Kai Jhong ◽  
Yafei Jia
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth ◽  
Foundation Design ◽  
Mobile Bed ◽  
Scour Hole ◽  
Scour Holes ◽  
Spur Dikes

Local scour is a common threat to structures such as bridge piers, abutments, and dikes that are constructed on natural rivers. To reduce the risk of foundation failure, the understanding of local scour phenomenon around hydraulic structures is important. The well-predicted scour depth can be used as a reference for structural foundation design and river management. Numerical simulation is relatively efficient at studying these issues. Currently, two-dimensional (2D) mobile-bed models are widely used for river engineering. However, a common 2D model is inadequate for solving the three-dimensional (3D) flow field and local scour phenomenon because of the depth-averaged hypothesis. This causes the predicted scour depth to often be underestimated. In this study, a repose angle formula and bed geometry adjustment mechanism are integrated into a 2D mobile-bed model to improve the numerical simulation of local scour holes around structures. Comparison of the calculated and measured bed variation data reveals that a numerical model involving the improvement technique can predict the geometry of a local scour hole around spur dikes with reasonable accuracy and reliability.

scholarly journals Energy Dissipation in Stilling Basins with Side Jets from Highly Convergent Chutes

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1343
Author(s):  
Rafael Moran ◽  
Miguel Ángel Toledo ◽  
Javier Peraita ◽  
Raffaella Pellegrino
Keyword(s):  
Energy Dissipation ◽  
Research Work ◽  
High Capacity ◽  
Design Parameters ◽  
Type I ◽  
Promising Alternative ◽  
Arch Dams ◽  
Stilling Basin ◽  
Stilling Basins ◽  
Conventional Alternative

Spillways with Highly Converging Chutes (HCCs) are a non-conventional alternative that can be applied to achieve a higher outflow capacity when the weir length exceeds the width of the valley at the toe of gravity or arch dams. This kind of spillway has been used in the past, but no general studies have yet been published. This article summarizes experimental research work aiming to increase the knowledge of the effect of some design parameters of HCCs on the energy dissipation in the stilling basin at the toe of the dam. As a comparison reference, we use the Type I stilling basins, widely known by the technical dam engineering community. The obtained results show that spillways with HCCs are a promising alternative to traditional designs, combining the ability to increase the weir length with a high capacity to dissipate energy through the impingement effect of the frontal and the side jets inside the stilling basin.

scholarly journals Prediction of maximum scour depth around piers with debris accumulation using EPR, MT, and GEP models

2016 ◽  
Vol 18 (5) ◽  
pp. 867-884 ◽  
Author(s):  
Mohammad Najafzadeh ◽  
Mohammad Rezaie Balf ◽  
Esmat Rashedi
Keyword(s):  
Polynomial Regression ◽  
Gene Expression Programming ◽  
Laboratory Data ◽  
Experimental Studies ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth ◽  
Effective Parameters ◽  
Pier Scour ◽  
Debris Accumulation

Pier scour phenomena in the presence of debris accumulation have attracted the attention of engineers to present a precise prediction of the local scour depth. Most experimental studies of pier scour depth with debris accumulation have been performed to find an accurate formula to predict the local scour depth. However, an empirical equation with appropriate capacity of validation is not available to evaluate the local scour depth. In this way, gene-expression programming (GEP), evolutionary polynomial regression (EPR), and model tree (MT) based formulations are used to develop to predict the scour depth around bridge piers with debris effects. Laboratory data sets utilized to perform models are collected from different literature. Effective parameters on the local scour depth include geometric characterizations of bridge piers and debris, physical properties of bed sediment, and approaching flow characteristics. The efficiency of the training stages for the GEP, MT, and EPR models are investigated. Performances of the testing results for these models are compared with the traditional approaches based on regression methods. The uncertainty prediction of the MT was quantified and compared with those of existing models. Also, sensitivity analysis was performed to assign effective parameters on the scour depth prediction.

scholarly journals Impact of Bed Material on the Local Scour Downstream Fayoum Type Weir with Various Designs of Floor Jets

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Ahmed Mahmoud Ibraheem
Keyword(s):  
Local Scour ◽  
Medium Sand ◽  
Stilling Basin ◽  
Water Jets ◽  
Materials By Design ◽  
Stilling Basins ◽  
Bed Materials ◽  
Tail Water ◽  
Bed Material ◽  
Fine Gravel

Local scour downstream hydraulic structures should be studied well to avoid damage or even failure of these structures. In this paper, an experimental model was conducted to study the influence of bed material size on the local scour downstream stilling basins of Fayoum type weir as a hydraulic structure. Two bed material were tested. The model included stilling basin and five rows of water jets. Forty-five test runs were carried out for each bed material. Different cases were implemented during this study including three flow discharges, three tail water depths and five various designs of floor jets. Based on the obtained results, it was found that the maximum and minimum scour depths for the two bed materials occurred by design A and design D. The maximum scour lengths happened for medium sand by design C and for fine gravel by both designs A and E, while the minimum scour lengths were recorded for medium sand by design D and for fine gravel by design A. The maximum scour volumes were found for the two bed materials by design A, while the minimum scour volumes occurred by both designs C and D for medium sand and by design E for fine gravel. Employing fine gravel instead of medium sand as a bed material achieved maximum reduction percentages of 86.8 %, 53.3 % and 89.8 % for scour depth, scour length and scour volume, respectively.

NEURO-FUZZY MODEL FOR ENVIRONMENTAL IMPACT ASSESSMENT

2011 ◽  
Vol 10 (3) ◽  
pp. 381-386 ◽  
Author(s):  
Alexandru Trandabat ◽  
Marius Pislaru ◽  
Silvia Avasilcai
Keyword(s):  
Environmental Impact ◽  
Impact Assessment ◽  
Environmental Impact Assessment ◽  
Fuzzy Model ◽  
Neuro Fuzzy

scholarly journals Neuro-Fuzzy Transformation with Minimize Entropy Principle to Create New Features for Particulate Matter Prediction

2021 ◽  
Vol 11 (14) ◽  
pp. 6590
Author(s):  
Krittakom Srijiranon ◽  
Narissara Eiamkanitchat
Keyword(s):  
Particulate Matter ◽  
Fuzzy Model ◽  
Original Data ◽  
Northern Region ◽  
National Standard ◽  
Minimum Entropy ◽  
Fuzzy Transformation ◽  
Neuro Fuzzy ◽  
Proposed Model ◽  
Entropy Principle

Air pollution is a major global issue. In Thailand, this issue continues to increase every year, similar to other countries, especially during the dry season in the northern region. In this period, particulate matter with aerodynamic diameters smaller than 10 and 2.5 micrometers, known as PM10 and PM2.5, are important pollutants, most of which exceed the national standard levels, the so-called Thailand air quality index (T-AQI). Therefore, this study created a prediction model to classify T-AQI calculated from both types of PM. The neuro-fuzzy model with a minimum entropy principle model is proposed to transform the original data into new informative features. The processes in this model are able to discover appropriate separation points of the trapezoidal membership function by applying the minimum entropy principle. The membership value of the fuzzy section is then passed to the neural section to create a new data feature, the PM level, for each hour of the day. Finally, as an analytical process to obtain new knowledge, predictive models are created using new data features for better classification results. Various experiments were utilized to find an appropriate structure with high prediction accuracy. The results of the proposed model were favorable for predicting both types of PM up to three hours in advance. The proposed model can help people who are planning short-term outdoor activities.

Characterization of polymer based composite using neuro-fuzzy model

2021 ◽  
Author(s):  
Safaa A.S. Almtori ◽  
Imad O. Bachi Al-Fahad ◽  
Atheed Habeeb Taha Al-temimi ◽  
A.K. Jassim
Keyword(s):  
Fuzzy Model ◽  
Neuro Fuzzy
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