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RISS 인기검색어
- 검색키워드
- 저자 : Arman Nasri (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Design a Methodology to Model-Reference Control of First Order Delays System
Arman Jahed,Farzin Piltan,Saman Namvarrechi,Iman Nazari,Ali Roshanzamir,Nasri B. Sulaiman 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.3
Design a nonlinear controller for second order nonlinear uncertain dynamical systems is one of the most important challenging works. This research focuses on the design, and analysis of a model-reference sliding mode controller for first order delay system, in presence of uncertainties. In order to provide high performance nonlinear methodology, model-reference sliding mode controller is selected. Pure sliding mode controller can be used to control of partly known nonlinear dynamic parameters. Conversely, pure sliding mode controller is used in many applications; it has an important drawback namely; chattering phenomenon. To attenuation the chattering, new filter based high speed control technique is introduced. In this technique, two type derivative techniques are used to improve the rate of delay as well stability, robustness and chattering attenuation. This technique cased to improve the rate of delay compare with conventional PID controller and conventional sliding mode controller.
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TADAS Dampers in Very Large Deformations
Reza Karami Mohammadi,Arman Nasri,Azin Ghaffary 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.2
Triangular-plate Added Damping and Stiffness (TADAS) dampers are special kinds of passive control devices that can be used in seismic design and retrofitting of structural systems. However, when exposed to large deformations, primary members of a structure can be in danger of serious damage due to improper geometric characteristics of these dampers. In this study, response of a one bay frame equipped with a TADAS device, previously tested in the laboratory, was simulated using a detailed FE model in ABAQUS. A monotonic analysis was then conducted on the TADAS damper alone, which indicated that in large deformations, TADAS damper pins hit the top of the holes, resulting in an abrupt stiffness increase in the damper. Seismic analysis of a six story moment resisting frame with TADAS dampers, using a series of twelve scaled earthquake ground motions, was also conducted in OpenSees which indicated that with sudden stiffness increase in dampers, the value of moments in beams as well as axial forces in braces will increase, causing possible damages in these areas. At the end, a method for calculating the optimal height for the holes in the damper was proposed, which is shown to be in good agreement with detailed ABAQUS models.
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Research on Nonlinear Automation for First Order Delays System
Ali Roshanzamir,Farzin Piltan,Arman Jahed,Saman Namvarchi,Nasri B. Sulaiman,Iman Nazari 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.9
First order delay system (FODS) is in class of nonlinear systems. In these systems design control algorithms are very important. In this research nonlinear terms of incremental Proportional Integral Derivative (PID) algorithm is used to nonlinear model-free integrate large amounts of control methodology in a single methodology. This work, proposes a developed method to design nonlinear based PID controller. In this methodology nonlinear model-free sliding mode algorithm help incremental PID to estimate and linearization of first order delay system. According to this research, the controller robustness improved based on nonlinear term of sliding mode algorithm and the chattering is reduced/eliminate based on PID incremental method.
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Improved analytical formulation for Steel-Concrete (SC) composite walls under out-of-plane loads
Saeid Sabouri-Ghomi,Arman Nasri,Younes Jahani,Anjan K. Bhowmick 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.4
The concept of using Steel-concrete (SC) composite walls as retaining walls has recently been introduced by the authors and their effectiveness of resisting out-of-plane loads has also been demonstrated. In this paper, an improved analytical formulation based on partial interaction theory, which has previously been developed by the authors, is presented. The improved formulation considers a new loading condition and also accounts for cracking in concrete to simulate the real conditions. Due to a limited number of test specimens, further finite element (FE)simulations are performed in order to verify the analytical procedure in more detail. It is observed that the results from the improved analytical procedure are in excellent agreement with both experimental and numerical results. Moreover, a detailed parametric study is conducted using the developed FE model to investigate effects of different parameters, such as distance between shear connectors, shear connector length, concrete strength, steel plate thickness, concrete cover thickness, wall’s width to thickness ratio, and wall’s height to thickness ratio, on the behavior of SC composite walls subjected to out-of-plane loads.
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Flexural performance of composite walls under out-of-plane loads
Saeid Sabouri-Ghomi,Arman Nasri,Younes Jahani,Anjan K. Bhowmick 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.4
This paper presents a new structural system to use as retaining walls. In civil works, there is a general trend to use traditional reinforced concrete (RC) retaining walls to resist soil pressure. Despite their good resistance, RC retaining walls have some disadvantages such as need for huge temporary formworks, high dense reinforcing, low construction speed, etc. In the present work, a composite wall with only one steel plate (steel–concrete) is proposed to address the disadvantages of the RC walls. In the proposed system, steel plate is utilized not only as tensile reinforcement but also as a permanent formwork for the concrete. In order to evaluate the efficiency of the proposed SC composite system, an experimental program that includes nine SC composite wall specimens is developed. In this experimental study, the effects of different parameters such as distance between shear connectors, length of shear connectors, concrete ultimate strength, use of compressive steel plate and compressive steel reinforcement are investigated. In addition, a 3D finite element (FE) model for SC composite walls is proposed using the finite element program ABAQUS and load-displacement curves from FE analyses were compared against results obtained from physical testing. In all cases, the proposed FE model is reasonably accurate to predict the behavior of SC composite walls under out-of-plane loads. Results from experimental work and numerical study show that the SC composite wall system has high strength and ductile behavior under flexural loads. Furthermore, the design equations based on ACI code for calculating out-of-plate flexural and shear strength of SC composite walls are presented and compared to experimental database.
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