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RISS 인기검색어
- 검색키워드
- 저자 : Saeed Asil Gharebaghi (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Optimization of the Double Reduced Beam Section (DRBS) Connection
Saeed Asil Gharebaghi,Reza Fami Tafreshi,Nader Fanaie,Omid Sepasgozar Sarkhosh 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.4
The double reduced beam section (DRBS) connection is a newly developed steel moment connection. In this paper, the chaotic particle swarm optimization technique was utilized to optimize this connection for the best seismic performance. The resulting optimum DRBS connection shapes showed up to 39% better energy dissipation and up to respectively 50% and 55% lower rupture index ( RI ) and equivalent plastic strain ( PEEQ ) at the beam-column interface, compared to the conventional RBS connection. Also, the optimum design parameters determined in this paper led to up to a 28% increase in the objective function (energy dissipation) and up to respectively 36% and 38% decreases in the RI and PEEQ with respect to the original DRBS connection, indicating noticeable seismic performance enhancements. The results indicated that changing the size of the beam and column sections does not lead to any signifi cant change in the optimal shape of the beam fl ange cut or the seismic performance of the connection.
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Chaotic particle swarm optimization in optimal active control of shear buildings
Saeed Asil Gharebaghi,Ehsan Zangooei 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.3
The applications of active control is being more popular nowadays. Several control algorithms have been developed to determine optimum control force. In this paper, a Chaotic Particle Swarm Optimization (CPSO) technique, based on Logistic map, is used to compute the optimum control force of active tendon system. A chaotic exploration is used to search the solution space for optimum control force. The response control of Multi-Degree of Freedom (MDOF) shear buildings, equipped with active tendons, is introduced as an optimization problem, based on Instantaneous Optimal Active Control algorithm. Three MDOFs are simulated in this paper. Two examples out of three, which have been previously controlled using Lattice type Probabilistic Neural Network (LPNN) and Block Pulse Functions (BPFs), are taken from prior works in order to compare the efficiency of the current method. In the present study, a maximum allowable value of control force is added to the original problem. Later, a twenty-story shear building, as the third and more realistic example, is considered and controlled. Besides, the required Central Processing Unit (CPU) time of CPSO control algorithm is investigated. Although the CPU time of LPNN and BPFs methods of prior works is not available, the results show that a full state measurement is necessary, especially when there are more than three control devices. The results show that CPSO algorithm has a good performance, especially in the presence of the cut-off limit of tendon force; therefore, can widely be used in the field of optimum active control of actual buildings.
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A new hybrid optimization algorithm based on path projection
Gharebaghi, Saeed Asil,Ardalan Asl, Mohammad Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6
In this article, a new method is introduced to improve the local search capability of meta-heuristic algorithms using the projection of the path on the border of constraints. In a mathematical point of view, the Gradient Projection Method is applied through a new approach, while the imposed limitations are removed. Accordingly, the gradient vector is replaced with a new meta-heuristic based vector. Besides, the active constraint identification algorithm, and the projection method are changed into less complex approaches. As a result, if a constraint is violated by an agent, a new path will be suggested to correct the direction of the agent's movement. The presented procedure includes three main steps: (1) the identification of the active constraint, (2) the neighboring point determination, and (3) the new direction and step length. Moreover, this method can be applied to some meta-heuristic algorithms. It increases the chance of convergence in the final phase of the search process, especially when the number of the violations of the constraints increases. The method is applied jointly with the authors' newly developed meta-heuristic algorithm, entitled Star Graph. The capability of the resulted hybrid method is examined using the optimal design of truss and frame structures. Eventually, the comparison of the results with other meta-heuristics of the literature shows that the hybrid method is successful in the global as well as local search.
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A new hybrid optimization algorithm based on path projection
Saeed Asil Gharebaghi,Mohammad Ardalan Asl 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6
In this article, a new method is introduced to improve the local search capability of meta-heuristic algorithms using the projection of the path on the border of constraints. In a mathematical point of view, the Gradient Projection Method is applied through a new approach, while the imposed limitations are removed. Accordingly, the gradient vector is replaced with a new meta-heuristic based vector. Besides, the active constraint identification algorithm, and the projection method are changed into less complex approaches. As a result, if a constraint is violated by an agent, a new path will be suggested to correct the direction of the agent's movement. The presented procedure includes three main steps: (1) the identification of the active constraint, (2) the neighboring point determination, and (3) the new direction and step length. Moreover, this method can be applied to some meta-heuristic algorithms. It increases the chance of convergence in the final phase of the search process, especially when the number of the violations of the constraints increases. The method is applied jointly with the authors' newly developed meta-heuristic algorithm, entitled Star Graph. The capability of the resulted hybrid method is examined using the optimal design of truss and frame structures. Eventually, the comparison of the results with other meta-heuristics of the literature shows that the hybrid method is successful in the global as well as local search.
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In-plane and out-of-plane waves in nanoplates immersed in bidirectional magnetic fields
Keivan Kiani,Saeed Asil Gharebaghi,Bahman Mehri 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.1
Prediction of the characteristics of both in-plane and out-of-plane elastic waves within conducting nanoplates in the presence of bidirectionally in-plane magnetic fields is of interest. Using Lorentz’s formulas and nonlocal continuum theory of Eringen, the nonlocal elastic version of the equations of motion is obtained. The frequencies as well as the corresponding phase and group velocities pertinent to the in-plane and out-of-plane waves are analytically evaluated. The roles of the strength of in-plane magnetic field, wavenumber, wave direction, nanoplate’s thickness, and small-scale parameter on characteristics of waves are discussed. The obtained results show that the in-plane frequencies commonly grow with the in-plane magnetic field. However, the transmissibility of the out-of-plane waves rigorously depends on the magnetic field strength, direction of the propagated transverse waves, small-scale parameter, and thickness of the nanoplate. The criterion for safe transferring of the out-of-plane waves through the conducting nanoplate immersed in a bidirectional magnetic field is also explained and discussed.
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