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Wind turbine power improvement utilizing passive flow control with microtab
, Article Energy ; Volume 150 , 2018 , Pages 575-582 ; 03605442 (ISSN) ; Movahhedi, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this study, the effect of deploying microtabs on performance improvement of a horizontal axis wind turbine blade is numerically investigated in three-dimensions. The NREL Phase VI, a stall-regulated upwind wind turbine, is used as the baseline case. Different cases are considered to investigate the effects of spanwise location as well as the height variation of tabs along the blade span, on the flow over the rotor blade. In all cases, the tab is located at 95% chord of the airfoil section on the lower surface of the blade. Results reveal that locating microtabs at the outboard part of the blade has a greater impact on the rotor performance than the inboard part. However, both cases...
Stabilizing periodic orbits of the fractional order chaotic van der pol system
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Vol. 8, Issue PARTS A AND B , 2010 , pp. 175-183 ; ISBN: 9780791844458 ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Abstract
In tins paper, stabilizing the unstable periodic orbits (UPO) in a chaotic fractional order system called Van der Pol is studied. Firstly, a technique for finding unstable periodic orbit in chaotic fractional order systems is stated. Then by applying tins technique to the van der Pol system, unstable periodic orbit of system is found. After that, a method is presented for stabilization of the discovered UPO based on theories stability of the linear integer order and fractional order systems. Finally, a linear feedback controller was applied to the system and simulation is done for demonstration of controller performance
Stabilizing periodic orbits of the fractional order chaotic van der pol system
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010, Vancouver, BC ; Volume 8, Issue PARTS A AND B , 2010 , Pages 175-183 ; 9780791844458 (ISBN) ; Salarieh, H ; Alasty, A ; Sharif University of Technology
2010
Abstract
In tins paper, stabilizing the unstable periodic orbits (UPO) in a chaotic fractional order system called Van der Pol is studied. Firstly, a technique for finding unstable periodic orbit in chaotic fractional order systems is stated. Then by applying tins technique to the van der Pol system, unstable periodic orbit of system is found. After that, a method is presented for stabilization of the discovered UPO based on theories stability of the linear integer order and fractional order systems. Finally, a linear feedback controller was applied to the system and simulation is done for demonstration of controller performance
Stabilizing periodic orbits of fractional order chaotic systems via linear feedback theory
, Article Applied Mathematical Modelling ; Vol. 36, Issue 3 , 2012 , pp. 863-877 ; ISSN: 0307904X ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Abstract
In this paper stabilizing unstable periodic orbits (UPO) in a chaotic fractional order system is studied. Firstly, a technique for finding unstable periodic orbits in chaotic fractional order systems is stated. Then by applying this technique to the fractional van der Pol and fractional Duffing systems as two demonstrative examples, their unstable periodic orbits are found. After that, a method is presented for stabilization of the discovered UPOs based on the theories of stability of linear integer order and fractional order systems. Finally, based on the proposed idea a linear feedback controller is applied to the systems and simulations are done for demonstration of controller performance...
Stabilizing periodic orbits of fractional order chaotic systems via linear feedback theory
, Article Applied Mathematical Modelling ; Volume 36, Issue 3 , 2012 , Pages 863-877 ; 0307904X (ISSN) ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Abstract
In this paper stabilizing unstable periodic orbits (UPO) in a chaotic fractional order system is studied. Firstly, a technique for finding unstable periodic orbits in chaotic fractional order systems is stated. Then by applying this technique to the fractional van der Pol and fractional Duffing systems as two demonstrative examples, their unstable periodic orbits are found. After that, a method is presented for stabilization of the discovered UPOs based on the theories of stability of linear integer order and fractional order systems. Finally, based on the proposed idea a linear feedback controller is applied to the systems and simulations are done for demonstration of controller performance...
Simulation and control of membrane reactors for catalytic reduction of dissolved oxygen from water
, Article Canadian Journal of Chemical Engineering ; 2017 ; 00084034 (ISSN) ; Golmakani, A ; Hosseinipoor, S ; Rokhforouz, M. R ; Sharif University of Technology
Wiley-Liss Inc
2017
Abstract
Removal of dissolved oxygen (DO) from water has gained much attention in recent decades to prevent different problems such as corrosion, bio-fouling, and performance degradation in many industries. The traditional physical and chemical methods for DO removal have found wide application in industries. However, physical methods have low efficiency and chemical methods often produce undesirable products. Therefore, catalytic reduction by hydrogen has been regarded by a variety of industries recently. In this study, catalytic reduction of DO from water is examined using membrane reactors. The mathematical model of this system is developed while considering the axial dispersion, membrane...
Simulation and control of membrane reactors for catalytic reduction of dissolved oxygen from water
, Article Canadian Journal of Chemical Engineering ; Volume 96, Issue 4 , 2018 , Pages 912-925 ; 00084034 (ISSN) ; Golmakani, A ; Hosseinipoor, S ; Rokhforouz, M. R ; Sharif University of Technology
Wiley-Liss Inc
2018
Abstract
The catalytic reduction of dissolved oxygen (DO) from water was examined using membrane reactors and a mathematical model that considers axial dispersion, membrane permeation, and chemical reaction. The model is solved in steady state mode and the effect of various parameters on the DO removal was assessed. The results of steady state mode were employed as initial conditions for solving the model in dynamic mode. The impact of operating conditions, e.g., water flow rate, DO concentration of influent water, hydrogen flow rate, and hydrogen pressure on the performance of the DO process was studied. Results of the dynamic simulation suggested that hydrogen pressure is the best option to be used...
Robust roll autopilot design to reduce couplings of a tactical missile
, Article Aerospace Science and Technology ; Volume 51 , 2016 , Pages 142-150 ; 12709638 (ISSN) ; Fathi Jegarkandi, M ; Moarrefianpour, A ; Sharif University of Technology
Abstract
The purpose of this work is to decrease coupling effects of a tactical missile by designing a robust autopilot for its roll channel. In tactical STT missiles due to control strategy, in order to execute acceleration commands, roll angular velocity should be kept close to zero. Generally, in the design of autopilot for many of tactical missiles the inter influences of channels is neglected. However, three channels of the missile impact each other in different ways including kinematic, inertia and aerodynamic couplings. Aerodynamic coupling is a dominant in roll channel dynamics appearing as induced and control cross coupling roll moments. In this paper first the coupling terms are modeled...
Robust control of LVAD based on the sub-regional modeling of the heart
, Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2934-2943 ; 10263098 (ISSN) ; Jahed, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
Left Ventricular Assist Devices (LVAD) have received renewed interest as a bridge-to-transplantation as well as a bridge-to-recovery device. Ironically, reports of malfunction and complications have hindered the growth of this device. In particular, the main concern is LVAD's susceptibility to excessive backlash and suction as a result of ows that are either too low or high, respectively. This study utilizes a well-established physiological model of the cardiovascular system as a reliable platform to study a proposed adaptive robust controller for a rotary motor based LVAD which overcomes such shortcomings. Proposed controller performance is evaluated by comparing simulated natural heart...
Planing craft control using pneumatically driven trim tab
, Article Mathematics and Computers in Simulation ; Volume 178 , December , 2020 , Pages 439-463 ; Zeinali, H ; Tamaddondar, M. H ; Sharif University of Technology
Elsevier B. V
2020
Abstract
Dynamic instabilities are quite common in planing crafts. This study deals with the elimination of one type of dynamic instabilities known as porpoising. The controller device is a pneumatically driven trim tab that applied to the transom of the boat. The governing dynamic equations of the planing craft and the pneumatically driven system are derived. The stability analysis of the system is carried out and porpoising instability is shown under some conditions. A dual control scheme consisting of the actuator control subsystem (inner control subsystem) and the planing craft (outer control subsystem) is proposed in order to control the planing craft from porpoising instability. Since the...
Notes on integral performance indices in fractional-order control systems
, Article Journal of Process Control ; Volume 20, Issue 3 , 2010 , Pages 285-291 ; 09591524 (ISSN) ; Sharif University of Technology
2010
Abstract
Integral performance indices as quantitative measures of the performance of a system are commonly used to evaluate the performance of designed control systems. In this paper, it is pointed out that due to existence of non-exponential modes in the step response of a fractional-order control system having zero steady state error, integral performance indices of such a system may be infinite. According to this point, some simple conditions are derived to guarantee the finiteness of different integral performance indices in a class of fractional-order control systems. Finally, some numerical examples are presented to show the applicability of the analytical achievements of the paper
Nonlinear optimal control of two-level large-scale systems; Part I - Interaction prediction principle
, Article ICIECA 2005: International Conference on Industrial Electronics and Control Applications 2005, Quito, 29 November 2005 through 2 December 2005 ; Volume 2005 , 2005 ; 0780394194 (ISBN); 9780780394193 (ISBN) ; Momeni, A. R ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
In this paper, which consists of two parts, a new two-level computational algorithm is used for nonlinear optimal control of large-scale systems. The two-level optimizer uses a new coordination strategy which is based on the gradient of interaction errors instead of the gradient of overall performance function. The advantages of the new method can be categorized into two parts: First, the new formulation is applicable to a large class of problems whilst the classical model coordination method is not. Second, it extremely reduces the number of iterations required for obtaining the overall optimal solution. Although the computational burden of the algorithm in the first level increases...
New robust control method applied to the locomotion of a 5-link biped robot
, Article Robotica ; 2019 ; 02635747 (ISSN) ; Salarieh, H ; Sharif University of Technology
Cambridge University Press
2019
Abstract
This paper proposes a new design of robust control combining feedback linearization, backstepping, and sliding mode control called FLBS applied to the locomotion of five-link biped robot. Due to the underactuated robot's model, the system has a hybrid nature, while the FLBS control can provide a stabilized walking movement even with the existence of large disturbances and uncertainties by implementing smooth chatter-free signals. Stability of the method is proven using the Lyapunov theorem based on the hybrid zero dynamics and Poincaré map. The simulations show the controller performance such as robustness and chatter-free response in the presence of uncertainty and disturbance. © 2020...
New robust control method applied to the locomotion of a 5-link biped robot
, Article Robotica ; 2019 ; 02635747 (ISSN) ; Salarieh, H ; Sharif University of Technology
Cambridge University Press
2019
Abstract
This paper proposes a new design of robust control combining feedback linearization, backstepping, and sliding mode control called FLBS applied to the locomotion of five-link biped robot. Due to the underactuated robot's model, the system has a hybrid nature, while the FLBS control can provide a stabilized walking movement even with the existence of large disturbances and uncertainties by implementing smooth chatter-free signals. Stability of the method is proven using the Lyapunov theorem based on the hybrid zero dynamics and Poincaré map. The simulations show the controller performance such as robustness and chatter-free response in the presence of uncertainty and disturbance. © 2020...
New robust control method applied to the locomotion of a 5-link biped robot
, Article Robotica ; Volume 38, Issue 11 , January , 2020 , Pages 2023-2038 ; Salarieh, H ; Sharif University of Technology
Cambridge University Press
2020
Abstract
This paper proposes a new design of robust control combining feedback linearization, backstepping, and sliding mode control called FLBS applied to the locomotion of five-link biped robot. Due to the underactuated robot's model, the system has a hybrid nature, while the FLBS control can provide a stabilized walking movement even with the existence of large disturbances and uncertainties by implementing smooth chatter-free signals. Stability of the method is proven using the Lyapunov theorem based on the hybrid zero dynamics and Poincaré map. The simulations show the controller performance such as robustness and chatter-free response in the presence of uncertainty and disturbance. Copyright ©...
Multimodel control of nonlinear systems: An improved gap metric and stability margin-based method
, Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME ; Volume 140, Issue 8 , 2018 ; 00220434 (ISSN) ; Haeri, M ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2018
Abstract
This paper presents a new multimodel controller design approach incorporating stability and performance criteria. The gap metric is employed to measure the distance between local models. An efficient method based on state feedback strategy is introduced to improve the maximum stability margin of the local models. The proposed method avoids local model redundancy, simplifies the multimodel controller structure, and supports employing of many linear control techniques, while does not rely on a priori experience to choose the gridding threshold value. To evaluate the proposed method, three benchmark nonlinear systems are studied. Simulation results demonstrate that the method provides the...
Modeling and Control of gas turbine combustor with dynamic and Adaptive Neural networks
, Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 1 , 2008 , Pages 71-84 ; 1728-144X (ISSN) ; Lahroodi, M ; Sharif University of Technology
Materials and Energy Research Center
2008
Abstract
This paper presents an Artificial Neural Network (ANN)-based modeling technique for prediction of outlet temperature, pressure and mass flow rate of gas turbine combustor. Results obtained by present modeling were compared with those obtained by experiment. The results showed the effectiveness and capability of the proposed modeling technique with reasonable accuracies of about 95 percent. This paper describes a nonlinear SVFAC (State Vector Feedback Adaptive Control) controller scheme for gas turbine combustor. In order to achieve the satisfied control performance, we have to consider the effect of nonlinear factors contained in controller. The controller is adaptively trained to force the...
Modeling and control of a grid-connected BDFM under unbalanced grid voltage conditions
, Article 2011 IEEE International Electric Machines and Drives Conference, IEMDC 2011, 15 May 2011 through 18 May 2011 ; May , 2011 , Pages 1647-1651 ; 9781457700613 (ISBN) ; Seyed Mahdi Izadkhast ; Khosravi, H ; Oraee, H ; Sharif University of Technology
2011
Abstract
This paper presents a mathematical model for Brushless Doubly-Fed Machine (BDFM) based on Stator Flux Orientation (SFO) in positive and negative reference frames under unbalanced grid voltage conditions. A negative controller is designed to eliminate the effects of unbalanced conditions on electrical torque. The model and controller performance during unbalanced conditions is validated by time domain simulation in MATLAB/Simulink
L1 Adaptive integrated guidance and control for flexible hypersonic flight vehicle in the presence of dynamic uncertainties
, Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 235, Issue 8 , 2021 , Pages 1521-1531 ; 09596518 (ISSN) ; Rezaee Ahvanouee, H ; Mohammadkhani, H ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
In this article, an integrated guidance and control design method for general nonlinear flexible hypersonic flight vehicles in the presence of dynamic uncertainties based on the (Formula presented.) adaptive state feedback control approach is presented. Initially, the 6-degree-of-freedom integrated guidance and autopilot dynamic model is organized using the combination of flexible uncertain hypersonic flight vehicle dynamic model and hypersonic flight vehicle-target relative motion model whereas aerodynamic and model uncertainties, cross-coupling effects, and disturbances are considered. The proposed integrated guidance and control method based on (Formula presented.) adaptive control scheme...
Introducing an adaptive robust controller for artificial heart
, Article Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, 24 June 2012 through 27 June 2012 ; June , 2012 , Pages 413-418 ; 21551774 (ISSN) ; 9781457711992 (ISBN) ; Jahed, M ; Sharif University of Technology
2012
Abstract
Prolonged and uncontrolled high shear stresses and turbulence can cause hemolysis, while alternating and low-level stresses may contribute to platelet activation and thrombus formation. Such deficiencies are reported for Total Artificial Heart (TAH) systems which are generally not fully capable of dynamic adaptation to sudden pressure and volume changes. This study introduces an adaptive robust controller for a linear motor based TAH (LMTAH) which overcomes such shortcomings. Proposed controller performance is compared with simulated natural heart in normal and stressed physiological conditions. Application of adaptive robust control results in flows with less stress variation and...