j. parsa

Accurate prediction of pore water pressure in the body of earth dams during construction with accurate methods is one of the most important components in managing the stability of earth dams. The main objective of this research is to develop hybrid models based on fuzzy neural inference systems and meta-heuristic optimization algorithms. In this regard, the fuzzy neural inference system and optimizing meta-heuristic algorithms including genetic algorithms (GA), particle swarm optimization algorithm (PSO), differential evolution algorithm (DE), ant colony optimization algorithm (ACOR), harmony search algorithm (HS), imperialist competitive algorithm (ICA), firefly algorithm (FA), and grey wolf optimizer algorithm (GWO) were used to improve training system. Three features including fill level, dam construction time, and reservoir level (dewatering) obtained from the dam instrumentation were selected as the inputs of hybrid models. The results showed that the hybrid model of the genetic algorithm in the test period had the best performance compared to other optimization algorithms with values of R2, RMSE, NRMSE, and MAE equal to 0.9540, 0.0866, 0.1232, and 0.0345, respectively. Also, ANFIS-GA, ANFIS-PSO, ANFIS-ICA, and ANFIS-HS hybrid algorithms performed better than ANFIS-GWO, ANFIS-FA, ANFIS-ACORE, and ANFIS-DE in improving ANFIS network training and predicting pore water pressure in the body earthen dams at the time of construction.

Duckbill weirs do not have a straight crest in the direction perpendicular to the flow. The plan view of the weir consists of multiple and broken linear crests that increase its effective length. The advantages of this type of weirs are their higher discharge capacity, easy aeration as well as low fluctuations of water surface at the weir upstream. In this study, discharge coefficient of the duckbill weir is investigated numerically. Numerical modeling is carried out by Fluent v. 6.2. The simulated velocity and pressure field are coupled by using "Piso" method. Reynolds governing equations, turbulence k –ε model, and the Volume of Fluid (VOF) model are numerically solved to define pressure and velocity. Also a few equations are proposed to define the relationship of discharge coefficients with some dimensionless hydraulic Parameters. Results showed that as the height of weir is increased, the discharge coefficient increases and the value of discharge coefficient is constant after H/P = 0.3 and is fixed on 0.47. Also the increase in weir height has a significant effect on the increase in the duckbill weir on discharge coefficient, which is an important factor in designing these weirs. Equation 8, with error value of 0.01695, is presented as the best equation to estimate the discharge coefficient over duckbill weirs.

For a cost-effective design of wave screen, an accurate estimation of dynamic pressure and wave force is needed. This study investigates the dynamic pressure action on elements of wave screen. The wave screen consists of several horizontal pipes with constant distance between them. This wave screen provides convection, interchanges of seawater within the harbor district, and makes available wave energy absorption effectively. The experimental were done on regular waves with 3 heights and 6 periods of waves at a constant water depth of 0.6 m. Also 3 difference diameters were considered for wave screen pipes. Dynamic pressures distribution along and around the pipes were measured by the pressure transducers. The results indicated that with increasing of the porosity, the pressure difference was decreased and with increasing of the incident wave height, pressure fluctuation for different porosity was increased. Furthermore, the maximum dynamic pressure fluctuation occurred at the angle more than 45°.