abbas barani

In this work, a multi-objective optimization process based on the genetic algorithm is employed to damp the vibrations of a piezo actuating composite beam. A new mathematical model for the control effort is proposed and optimized with two objective functions. Conflicting objectives are considered as the displacement of the beam and the second derivative of the control voltage. The coefficients of the proposed control voltage model are regarded as the design variables for this optimization process. The corresponding Pareto front represents non-dominated optimum solutions with different choices to designers. The time behaviors of displacement, velocity and acceleration as well as the related control effort at the midpoint of the beam for three optimum design points are illustrated. The simulation of the time responses of a selected optimum point exhibits the advantage of the planned optimum strategy with regard to those stated in some research such as the cases used in the maximum principle for the same structure.

Urmia Lake, as a hyper saline and very shallow lake, located in the northwest of Iran, has had reduced water level of about 40 centimeters each year over the past two decades and is drying, which this problem has led to social and environmental consequences. In this research, the indexes of environmental and agricultural sustainability were evaluated using performance criteria influenced by climate change and water management strategies for the Zerrinehrud and Siminehrud river basins as the largest sub-basin of Urmia Lake Basin. Modeling of hydrologic behavior of these basins was performed by WEAP21 model. The LARS-WG downscaling model was used to simulate climate change.Then the model was analyzed for three future emission scenarios (A2, A1B and B1), for the period 2015-2040, and five water management scenarios: (1) keeping the existing situation (S0), (2) crop pattern change (S1), (3) improving the conveyance and distribution efficiency (S2), (4) combining the improvement of conveyance and distribution efficiency with improving the application efficiency using modern technology (S3), and (5) the combination of crop pattern change with the improvement of total irrigation efficiency (S4). The results showed that the highest values of indices ​​of environmental sustainability and agricultural sustainability were related to the scenario of combining the crop pattern change with improving the total irrigation efficiency under the B1 emission scenario (B1S4). In this scenario, the average annual flow of water entering the Urmia Lake from Zarrinehrud and Siminehrud river basins will be equal to 1292 and 351 MCM per year, and as a result, the environmental flow requirements of the lake will be supplied from these basins.

  One of the general categories for discretization of equations and creation of computational geometry in the numerical methods is mesh-based and mesh-free methods. Previously, mesh-based methods have been a useful tool for flow modeling. However, these methods have some limitations for modeling of free surface flows, changeable boundaries and complicated geometry. In recent years, new generation of computational fluid dynamics methods named mesh-free methods has been introduced which one of them is smoothed particle hydrodynamics method. Smoothed particle hydrodynamics method is a fully Lagrangian method which solves the computational domain without using meshes. In this method, the integral expression is used for the approximation of functions, and smoothed functions have a key role in integral approximations. In the present study, the Incompressible Smoothed Particle Hydrodynamics method has been utilized for modeling of the dam break waves. In order to validation of the computational results, the reports of two experiments of dam break problem have been used. For the numerical modeling, the cubic spline function and initial distance between particles of 0.003 m, 0.004 m, 0.006 m & 0.008 m have been used, and the sensitivity analysis has been done on the effect of the initial distance between particles. Also, the effects of quantic spline smoothed function and beta smoothed function on results of modeling for two experimental data with the initial distance between particles of 0.006 m have been performed to reduce the computational costs. After reviewing the results of the modeling and comparison of the mean relative error related to each of smoothed functions were found that the most accurate results are related to the cubic spline smoothing function. In order to investigate the influence of the initial distance between particles in the modeling, a comparison was made between the results of the numerical model for various distances of 0.003 m, 0.004 m, 0.006 m, and 0.008 m for two experimental dam break tests for the superior cubic spline smoothed function. The results demonstrated that the ability of the numerical model has been enhanced by reducing the initial distance between the particles (increase the number of particles) in which applying the initial distance of 0.003 m would improve the results of the wave front by 43.5% and water level oscillation by 93.7% compared to the initial distance of 0.008 m. Keywords: Free-surface flows, Dam break, Numerical modeling, Incompressible Smoothed Particle Hydrodynamics method

Estimation of maximum scour depth is an important factor in designing structures that are embedded in rivers. Using a hydraulic model, the mechanism of local scour around bridge piers that are embedded in cohesive soils has been studied. Experiments were performed in a flume of 22m long, 0.77m wide and 0.60 m deep with a pier of 0.1 m in diameter. Also, three types of cohesive soils with different percent clay were used. While changing parameters, such as current velocity, flow depth, initial moisture content, clay percentage, and undrained shear strength in each experiment, the scour depths were measured.The measured data was adjusted by hyperbolic law. Using dimensional analysis, a relationship between the ultimate scour depth and effective parameters was developed. Finally, the ultimate scour depths obtained by experiments were compared with those calculated by empirical equations.

Estimation of maximum scour depth is an important factor in designing structures that are embedded in rivers. Using a hydraulic model, the mechanism of local scour around bridge piers that are embedded in cohesive soils has been studied. Experiments were performed in a flume of 22m long, 0.77m wide and 0.60 m deep with a pier of 0.1 m in diameter. Also, three types of cohesive soils with different percent clay were used. While changing parameters, such as current velocity, flow depth, initial moisture content, clay percentage, and undrained shear strength in each experiment, the scour depths were measured.The measured data was adjusted by hyperbolic law. Using dimensional analysis, a relationship between the ultimate scour depth and effective parameters was developed. Finally, the ultimate scour depths obtained by experiments were compared with those calculated by empirical equations.