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Evaluation of Strength Loss due to Diagonal Crack and Parameters Affecting it in Masonry Infill Walls
, M.Sc. Thesis Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
Masonry infills are vastly used as surrounding walls and partitions. Presence of infill in a building causes some change in strength, stiffness, period and generally seismic behavior of the structure.Mainly there are 5 modes of failure including 1- interface cracking 2- sliding along bed joint 3- diagonal cracking 4- corner crushing and 5- ultimate failure. According to these failures, three stages of strength as shear strength, corner strength and ultimate strength can be defined.Diagonal crack can be calculated by slip surface method grown in Sharif university of Technology. Based on this method the strength of infill wall falls down as the cohesive strength of mortar loses and so the slip...
Synchronization of chaotic systems using variable structure controllers
, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 10716947 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Alasty, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006
Abstract
In this paper a variable structure system based upon sliding mode control with time varying sliding surface and variable boundary layer is introduced to synchronize two different chaotic systems with uncertain parameters. The method is applied to Lur'e-Genesio chaotic systems, as drive-response systems to investigate the effectiveness and robustness of the controlling method. In addition the simulation is repeated with a conventional sliding mode to compare the performance of the proposed sliding mode technique with a simple sliding mode control. The results show the high quality and improved performance of the method presented in the paper for synchronization of different drive-response...
Finite time control of robotic manipulators with position output feedback
, Article International Journal of Robust and Nonlinear Control ; Volume 27, Issue 16 , 2017 , Pages 2982-2999 ; 10498923 (ISSN) ; Moravej Khorasani, M ; Haeri, M ; Sharif University of Technology
Abstract
This paper deals with the robust finite time tracking of desired trajectories for a wide group of robotic manipulators in spite of unknown disturbances, uncertainties, and saturations of actuators while only manipulator's positions are available and its velocities are not measurable physically. A new form of chattering-free second order fast nonsingular terminal sliding mode control scheme is introduced to design input torques for fulfilling the determined tracking objective in the adjustable total finite settling time. The proposed control algorithm is incorporated with two nonlinear observers to estimate disturbances and velocities of joints within finite settling times. The global finite...
Stabilisation of commensurate fractional-order polytopic non-linear differential inclusion subject to input non-linearity and unknown disturbances
, Article IET Control Theory and Applications ; Volume 7, Issue 12 , 2013 , Pages 1624-1633 ; 17518644 (ISSN) ; Haeri, M ; Sharif University of Technology
2013
Abstract
In this study, a fractional-order adaptive-sliding mode control (SMC) scheme is proposed to stabilise commensurate fractional-order polytopic non-linear differential inclusion systems containing sector and dead-zone nonlinearities in the control inputs and unknown bounded disturbances. The suggested control method is composed of fractional-order sliding surfaces, adaptive-SMC inputs and adaptation laws for unknown bounds of disturbances. The Lyapunov stability theorem is used to prove the stability of the closed-loop system. A practical system and two numerical examples are simulated to show the effectiveness and performance of the proposed control technique
A new fast finite time fractional order adaptive sliding-mode control for a quadrotor
, Article 7th International Conference on Control, Instrumentation and Automation, ICCIA 2021, 23 February 2021 through 24 February 2021 ; 2021 ; 9780738124056 (ISBN) ; Vedadi Moghaddam, T ; Emamifard, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Fast finite time adaptive sliding mode control of a quadrotor in the presence of uncertainties and unbounded external disturbances is dealt in this paper. To this end, a fractional order sliding surface is first defined and then, an adaptive sliding mode controller is designed to guarantee finite time stability with fast convergence of quadrotor states to the desired trajectory. In this controller, it is assumed that the upper bound of the model uncertainties and external disturbances is a nonlinear function with unknown coefficients. These coefficients are estimated via stable adaptive laws. Finite time stability of the closed-loop system is analyzed using Lyapunov theorem. Simulation...
Optimal sliding mode control of AFM tip vibration and position during manipulation of a nanoparticle
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Vol. 12, Issue. PART A , 2010 , pp. 205-214 ; ISBN: 9780791843857 ; Khorsand, M ; Meghdari, A ; Alasty, A ; Sharif University of Technology
Abstract
This research regards to a two-dimensional lateral pushing nanomanipulation using Atomic Force Microscope (AFM). Yet a reliable control of the AFM tip position during the AFM-based manipulation process is a chief issue since the tip can jump over the target nanoparticle and then the process can fail. However, a detailed Modeling and understanding of the interaction forces on the AFM tip is important for prosperous manipulation control and a nanometer resolution tip positioning. In the proposed model, Lund-Grenoble (LuGre) dynamic friction model is used as friction force on the contact surface between the nanoparticle and the substrate. This model leads to a stick-slip behavior of the...
Optimal sliding mode control of AFM tip vibration and position during manipulation of a nanoparticle
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings, 13 November 2009 through 19 November 2009, Lake Buena Vista, FL ; Volume 12, Issue PART A , 2010 , Pages 205-214 ; 9780791843857 (ISBN) ; Khorsand, M ; Meghdari, A ; Alasty, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2010
Abstract
This research regards to a two-dimensional lateral pushing nanomanipulation using Atomic Force Microscope (AFM). Yet a reliable control of the AFM tip position during the AFM-based manipulation process is a chief issue since the tip can jump over the target nanoparticle and then the process can fail. However, a detailed Modeling and understanding of the interaction forces on the AFM tip is important for prosperous manipulation control and a nanometer resolution tip positioning. In the proposed model, Lund-Grenoble (LuGre) dynamic friction model is used as friction force on the contact surface between the nanoparticle and the substrate. This model leads to a stick-slip behavior of the...
Time saving simulation of long train derailment
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 17 , 2009 , Pages 461-465 ; 9780791848784 (ISBN) ; Jalili, M. M ; Sharif University of Technology
2009
Abstract
This article presents a new method in determining long train derailment. A new strategy for building train models with large number of wagons has been developed. Previous studies have shown that in a train model, some of the details in the model of the wagons neighboring the wagon under study play minor role in dynamic behavior of the spotted wagon. To reduce the size of the overall model, one would tend to eliminate some of the details of the complex neighboring model having minor effect on overall behavior and trade a small approximation in results for large saving in computation time. In this research this idea is used to develop a train model with one full detail wagon model linked in a...
Sliding mode robust control of the horizontal wind turbines with model uncertainties
, Article 2020 9th International Conference on Modern Circuits and Systems Technologies, MOCAST 2020, 7 September 2020 through 9 September ; 2020 ; Moradi, H ; Vossoughi, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Wind turbines are generally controlled based on two control objectives: Turbine protection and the generation of acceptable power for the grid. In this paper, a robust control strategy is presented for switching between various operating modes of the turbine. The rotor angular speed is hold below the allowable speed in all operation time. It is also attempted to catch a constant power in a desirable amount during the most of operation time. For the elimination of model/environmental uncertainties, sliding mode controllers are used. For the objective of power tracking, the stability of sliding mode controller is proved for a set of sliding surfaces. Advantages and disadvantages of the...
Application of fractional derivative in control functions
, Article Proceedings of the INDICON 2008 IEEE Conference and Exhibition on Control, Communications and Automation, 11 December 2008 through 13 December 2008, Kanpur ; Volume 1 , 2008 , Pages 252-257 ; 9781424427475 (ISBN) ; Haeri, M ; Sharif University of Technology
2008
Abstract
Application of fractional derivative in control problems such as sliding surface design in Sliding Mode Control, training of MLP in neural networks, and parameters updating in Model Reference Adaptive Control is studied in this paper. Use of the fractional derivative increases possibility of improving the control performance by reducing the convergence time in the mentioned control problems. This gain is attained due to the higher degree of freedom exist in the fractional dynamical systems. We study such control problems by replacing the integer order derivative with the fractional order derivative. The performance of the proposed methods is illustrated through computer simulations of gyro...
A non-linear controller design for the evaporator of a heat recovery steam generator
, Article Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy ; Volume 223, Issue 5 , 2009 , Pages 535-541 ; 09576509 (ISSN) ; Nademi, H ; Sharif University of Technology
2009
Abstract
This article addresses a combined approach of sliding mode control (SMC) with generalized predictive control (GPC) to achieve fluid temperature control in the evaporator of a heat recovery steam generator. The evaporator is modelled as a first-order plus dead time process. The model is developed using the experimental data obtained at an actual power plant. An output error identification algorithm is used to minimize the error between the model and the experiments in different operating conditions. A GPC method is exploited to optimize the sliding surface and the coefficients of the switching functions used in SMC. The proposed control schemes are evaluated by thorough simulation for...