Shojaee S.,Shahid Bahonar University of Kerman |
Mohammadian M.,Islamic Azad University at Ferdows
Structural and Multidisciplinary Optimization | Year: 2011
In this paper, we combine a Piecewise Constant Level Set (PCLS) method with a MBO scheme to solve a structural shape and topology optimization problem. The geometrical boundary of structure is represented implicitly by the discontinuities of PCLS functions. Compared with the classical level set method (LSM) for solving Hamilton-Jacobi partial differential equation (H-J PDE) we don't need to solve H-J PDE, thus it is free of the CFL condition and the reinitialization scheme. For solving optimization problem under some constraints, Additive Operator Splitting (AOS) and Multiplicative Operator Splitting (MOS) schemes will be used. To increase the convergency speed and the efficiency of PCLS method we combine this approach with MBO scheme. Advantages and disadvantages are discussed by solving some examples of 2D structural topology optimization problems. © 2011 Springer-Verlag.
Mirzaei S.M.,Islamic Azad University at Ferdows |
Moattar M.H.,Islamic Azad University at Mashhad
International Journal of Electrical and Computer Engineering | Year: 2015
Fish robot precision depends on a variety of factors including the precision of motion sensors, mobility of links, elasticity of fish robot actuators system, and the precision of controllers. Among these factors, precision and efficiency of controllers play a key role in fish robot precision. In the present paper, a robot fish has been designed with dynamics and swimming mechanism of a real fish. According to equations of motion, this fish robot is designed with 3 hinged links. Subsequently, its control system was defined based on the same equations. In this paper, an approach is suggested to control fish robot trajectory using optimized PID controller through Bacterial Foraging algorithm, so as to adjust the gains. Then, this controller is compared to the powerful Fuzzy controller and optimized PID controller through PSO algorithm when applying step and sine inputs. The research findings revealed that optimized PID controller through Bacterial Foraging Algorithm had better performance than other approaches in terms of decreasing of the settling time, reduction of the maximum overshoot and desired steady state error in response to step input. Efficiency of the suggested method has been analyzed by MATLAB software. © 2015 Institute of Advanced Engineering and Science. All rights reserved.
Choobbasti A.J.,Babol Noshirvani University of Technology |
Zahmatkesh A.,Islamic Azad University at Ferdows |
Noorzad R.,Babol Noshirvani University of Technology
Geotechnical and Geological Engineering | Year: 2011
Stone columns (or granular piles) are increasingly being used for ground improvement. This study investigates the qualitative and quantitative improvement in soft clay by stone columns. Finite element analyses were carried out to evaluate the performance of stone columns in soft clay. A drained analysis was carried out using Mohr-Coulomb's criterion for soft clay, stones, and sand. The interface elements were used at the interface between the stone column and soft clay. Analyses and calculations were carried out to determine equivalent parameters of soil/columns system. The bearing capacity ratio (BCR) of the soil has been estimated for homogeneous and heterogeneous soil. The results have shown that the values of BCR for homogeneous soil are obviously higher than those for heterogeneous soil. © 2011 Springer Science+Business Media B.V.
Amini M.M.,Islamic Azad University at Ferdows |
Motlagh M.R.J.,Iran University of Science and Technology
Proceedings - 2011 2nd International Conference on Control, Instrumentation and Automation, ICCIA 2011 | Year: 2012
In this paper the new one-degree and two-degree of freedom H ∞ loop shaping robust controllers are designed for a seeker scan loop, which has model uncertainty and subjects to external & internal disturbances. Both one-degree and two-degree of freedom H∞ loop shaping are constructed of two main stages; first, the nominal plant is dynamically diagonalized and shaped by pre- and post-compensators to give a desired shape to the singular values of the open loop frequency response and then shaped plant robustly stabilized with respect to coprime factor uncertainty using simple H∞ optimization and γ-iteration for one-degree of freedom H∞ loop shaping and two-degree of freedom H∞ loop shaping respectively. Finally, designed controllers are applied to the plant and simulation results in time and frequency domains such as step response, external and process disturbances rejection, robust performance and scan performance are shown and compared for these controllers and some other works. © 2011 IEEE.
Es'haghi Z.,Payame Noor University |
Mohtaji M.,Islamic Azad University at Mashhad |
Hasanzade-Meidani M.,Islamic Azad University at Mashhad |
Hasanzade-Meidani M.,Islamic Azad University at Ferdows |
Masrournia M.,Islamic Azad University at Mashhad
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2010
New pre-concentration technique, triple phase suspended droplet microextraction (SD-LPME) and liquid chromatography-photodiode array detection was applied to determine ecstasy, MDMA (3,4-methylendioxy-N-methylamphetamine) in hair samples. In this research MDMA in hair was digested and after treatment extracted. The effective parameters were investigated and method was evaluated. Under the optimal conditions, the MDMA was enriched by factor 98.11. Linearity (r = 0.9921), was obtained in the range of 10-15,000 ng mL-1 and detection limit was 0.1 ng mL-1. © 2010 Elsevier B.V. All rights reserved.