Loading...
Search for:
kamankesh--amin
0.135 seconds
Total 246 records
Stability Analysis of Nonlinear Periodically Time-Varying Dynamic Systems By Studying Typical Insect-Like Flapping Wing
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
Designing Nonautonomous periodic systems such as helicopters, multirotors, monocopters or the dynamics of flapping wings requires stability analysis and careful examination in order to identify and determine their dynamic behaviour. In practice, analysis and design are interdependent and the design of nonlinear control systems involves an iterative process. To know the importance of identifying and to accurately implement methods to analyse this kind of systems in the field of aerospace, the flapping wing can be a good example. The issue of stability and the control of the flapping wings have not yet had a clear solution, and the current research including controller design based on linear...
Seismic Vulnerability Assessment of Masonry Infilled RC Frames with Different Infill Configuration and Opening
, M.Sc. Thesis Sharif University of Technology ; Bakhshi, Ali (Supervisor)
Abstract
Reinforced concrete buildings with open ground storey are vulnerable to accumulate of large lateral displacement at the ground story. This is due to drastic reduction in the relative stiffness of the ground story compared to the upper stories, a phenomenon known as soft storey effect. Furthermore inevitable Existence of Opening in masonry infill and increasing it’s area reduces both the lateral strength and stiffness of the fully infilled RC frames so when percentage of the central opening is very high, the behaviour of the infilled frame approaches the bare frame. It is a perception about open ground storey buildings that openings in the upper stories infilled frame offset the soft storey...
Stability analysis for design improvement of bio-inspired flapping wings by energy method
, Article Aerospace Science and Technology ; Volume 111 , 2021 ; 12709638 (ISSN) ; Banazadeh, A ; Sharif University of Technology
Elsevier Masson s.r.l
2021
Abstract
This study attempts to reach a broad understanding of the stability properties of nonlinear time-periodic flapping wing structures. Two bio-system models, Hummingbird (6DOF) and Hawkmoth (3DOF) are developed for this purpose. Initial analysis on the Hummingbird model, which is based on the Floquet theory, kinetic energy integration, and phase portrait technique, indicates lack of stability in hover flight. Kinetic energy integration is carried out on the extended model of the Hawkmoth to find the domain of attraction and increase the level of stability by varying the design parameters. Here, the hinge location of the wing, flapping amplitude, flapping frequency, and mean angle of attack are...
Frequency domain identification of a tapered beam embedded by piezoelectric layer
, Article 2016 International Conference on Advanced Mechatronic Systems, ICAMechS 2016, 30 November 2016 through 3 December 2016 ; 2017 , Pages 312-317 ; 23250682 (ISSN); 9781509053469 (ISBN) ; Ahranjani, F. F ; Kamankesh, Z ; Sharif University of Technology
IEEE Computer Society
2017
Abstract
This study is conducted aiming to identify the dynamics of a tapered beam, embedded by piezoelectric layer. Narrowing the tip of the beam equipped with piezoelectric patches leads to optimize the output power after excitation by the frequency sweep input. An accelerometer is installed on the beam base, which measures the acceleration that is applied to the system. Piezoelectric sensors also measure the generated voltage. The experimental test data is handled through CIFER software, using Fourier transform and Bode plot in the frequency domain, to obtain appropriate transfer functions. MATLAB is used for nonlinear simulation and validation of discrete transfer functions by a set of data that...
Effect of strain path change on mechanical properties and final microstructure of Cu-Al2O3 in equal channel angular pressing
, Article Materials Science and Technology (United Kingdom) ; Volume 29, Issue 2 , 2013 , Pages 210-218 ; 02670836 (ISSN) ; Serajzadeh, S ; Akhgar, J. M ; Kamankesh, A ; Sharif University of Technology
2013
Abstract
In the present work, the process of equal channel angular pressing of dispersion strengthened Cu-1̇1 wt-%Al2O3 containing nanometric alumina particles was investigated by means of mathematical modelling and experimental testing. Through the modelling, deformation parameters such as hydrostatic pressure distribution and strain field were determined, and the effect of deformation path on these parameters was estimated. Equal channel angular pressing as well as mechanical and microstructural evaluations were also conducted to assess mechanical properties, grain structure and void volume fraction after deformation in different routes. The results indicate that distributions of plastic strain and...
Liquid-liquid equilibrium (LLE) data for ternary mixtures of {aliphatic+p-xylene+[EMpy][ESO 4]} at T=313.15K
, Article Fluid Phase Equilibria ; Volume 332 , 2012 , Pages 48-54 ; 03783812 (ISSN) ; Vossoughi, M ; Shamloo, A ; Mirkhani, S. A ; Akbari, J ; Sharif University of Technology
Elsevier
2012
Abstract
Liquid-liquid equilibrium (LLE) data for the ternary systems (heptane. +. p-xylene. +. 1-ethyl-3-methylpyridinium ethylsulfate) and (n-octane. +. p-xylene. +. 1-ethyl-3-methylpyridinium ethylsulfate) were measured at . T=. 313.15. K and atmospheric pressure. The selectivity and aromatic distribution coefficients, calculated from the equilibrium data, were used to determine if this ionic liquid can be used as a potential extracting solvent for the separation of p-xylene from heptane and n-octane. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations
Introducing a Simulation-Based Model to Improve the Design and Layout of Workstations Inside Airport Terminals in Iran
, M.Sc. Thesis Sharif University of Technology ; Alvanchi, Amin (Supervisor)
Abstract
The airport terminal is difficult to plan and design due to the different components and the intricate complexity of its parts. At the airport terminal, we face a queue system which simulation is always a good way to analyze. In addition, computer simulation using modern softwares with the capability to model different types of systems, including the airport terminal, while being less realistic than analytical models, is less costly than operational Exercise.In this study, a supportive approach for better and specific management of Iranian airport terminal buildings with discrete-event simulation is proposed, considering the need for managing the airport terminals building in the country and...
Evaluation of Process Partitioning of Enzyme in Polymer-Salt Aqueous Two-PHase Systems
, M.Sc. Thesis Sharif University of Technology ; Alamzadeh, Iran (Supervisor) ; Vossoughi, Manouchehr (Supervisor) ; Pazuki, Gholamreza (Supervisor)
Abstract
In this research, the amount of partitioning Invertase to be evaluated in nine systems, these systems contain Peg 2000,Peg 4000 & Peg 6000 with three different salt.In first, Binodal curve for nine systems to be drown by cloudy point method, then five point be selected in each system such as sample feed. Invertase in every systems to be solved in constant weight fraction. The analysis of every phasesto be achieved by Merchuk method. For correlation data of this method to be used by Othmer-Tobias method and then using equation Mrchvk ensure the accuracy of phase analysis , analysis of the results obtained with the UV method was studied.Accuracy of UV analysis was studied by using lattice...
, M.Sc. Thesis Sharif University of Technology ; Alvanchi, Amin (Supervisor)
Abstract
Limited water resources in Iran have made dams an important part of the country’s infrastructure. As a result of the large number of in-progress and expected dam projects in the country, consideration of sustainability factors during planning, construction and operation phases of dam projects can create significant economical, social and environmental impacts in the long term. To come up with an inclusive sustainable development, new sustainability assessment approaches seek for sustainable development at the entire project’s life-cycle; they are looking for sustainable development at all design, construction, operation, maintenance and even demolition phases. In this research we have...
The Insider Threat: Analyzing and Modeling
, M.Sc. Thesis Sharif University of Technology ; Hendesi, Faramarz (Supervisor)
Abstract
Nowadays, most of businesses are becoming computer-based. This trend causes the organizations to become more vulnerable to internal and external threats. Internal threats are done through insiders. Insiders unlike outsiders have capabilities which aid them to easily carry out their illicit activities. Unfortunately, most of research in computer security has focused on the outsider threats, whereas the most damaging is the result of insiders’ illicit activities.This dissertation addresses three primary necessities of the research in the area of insider threat: a consistent definition of insider threat, a classification of types of insider threats, and a classification of vulnerabilities which...
Integrity Analysis in the Time-Delay Systems
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
Integrity of closed-loop systems with integral action control is characterized by using a series of successively more difficult to obtain conditions: Integral Stabilizable (IS), Integral Controllable (IC), Integral Controllable with Integrity (ICI), and Decentralized Integral Controllability (DIC). The IS condition requires that for a Linear Time-Invariant (LTI) finitedimensional (FD) plant, G(s), one finds a stabilizing decentralized controller with integral action. For G(s) to be IC, in addition to being IS, one should be able to reduce the gain of
all control loops by the same factor from a finite value to (but not including) zero without introducing instabilities. ICI requires that...
all control loops by the same factor from a finite value to (but not including) zero without introducing instabilities. ICI requires that...
Design of a Plantwide Decentrlized Structure Controller for the Tennessee Eastman Challenge Problem
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
This project focuses on the Tennessee East-man challange problem(TEP) and the impact of setpoint changes and controller tunning on plant performance and profitability. TE has four major units. it is an unstable system due to the reaction within the reactor and a recycle streamcausing snow ball effect. As a result the control of this system is not easy. The study has been conducted along two main directions. First, selecting the optimal values for the setpoints and applying them in the simulation. secondly, try to find better parameter for controller in simulation. Simulation is based on working of Ricker. In TEP like the other multivariable systems, it is ameanable to use a centralized...
A Thesis Submitted in Partial Fulfillment of the Requirement for the Degree of Master of Science in Electrical Engineering
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
Intraction in multi input multi output (MIMO) system makes control of these systems difficult.There are two ways to control such systems; Centralized and Decentralized control. One way in which a centralized controller is designed is using a precompensator. With application of the pre-compensator, the MIMO sytem is decoupled into several SISO systems and one can control these seperatly. Almost all previews methods for the design of pre-compensator assume that the model of the plant containsno uncertainties.In this thesis a new method is proposed which takes into account model uncertaintes in the design of the pre-compensator.The form of the uncertainties considred an interval-parametric
Convex Methods for the Design of Low Order Dynamic Pre-Compensators
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
Decentralized control is a typical method for the design of industrial MIMO control systems. However, in most multivariable systems, the existence of large interactions limit the achievable performance of such controllers. In the Nyquist Array design method proposed by Rosenbrock, the system interactions can be reduced using a precompensator, such that a decentralized controller may be used with acceptable performance. A well designed pre-compensator will effectively decouple the system and the multivariable systems may be considered as a set of SISO systems. It is therefore obvious that the key element in the Nyquist Array design method is the design of the pre-compensator. There are two...
Developing a Sustainable Model for Bridge Maintenance in Big Organisations
, M.Sc. Thesis Sharif University of Technology ; Alvanchi, Amin (Supervisor)
Abstract
For increasing longevity of a structure, it is not enough to notice only to designing aspects. In operation phase of a construction, we can increase the level of service and longevity. Asset-based Organizations, in addition to design their new assets, should maintain them. Infrastructures, such as road, bridge, dam, and water network, are important because of social and economic aspects. So they need special attention. There are efficient models for infrastructure maintenance that consider infrastructure element information, such as condition rate, weight, dimensions, deterioration rate, and cost of maintenance as inputs and give planning for maintenance in future. This planning, involves a...
Conditions for Integrity of Multivariable Systems with Input Saturation
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
Multivariable control systems as used in the industry usually contain integral action in order to improve tracking of the output with respect to step reference changes. These systems are usually subject to input saturation due to actuator or sensor nonlinearities. The aim of this work is find the conditions for the integrity concept of such multivariable system, e.g. IS, IC, ICI and DIC. First we develop the conditions on the controller gains necessary stabilize the systems and then show that these conditions can changes when one examines integrity conditions
Decentralized Integral Controller Design to Possess Integrity
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
Design of fault tolerant controllers with a reliable and robust control structure that can accommodate sensor and actuator failure is a challenging problem. In the process control literature, the term “integrity” is used to characterize these properties for decentralized control systems. It refers to the ability to retain system stability when one or some of the control loops get in or out of service or when loop gains are detuned.Conditions pertaining to the integrity of the closed-loop system are described by a series of successively more difficult to attain criteria whose evaluation is only based on the process steady state gains. These are Integral stabilizibility (IS), Integral...
Disturbance Diagnosis In Plant-wide Processes
,
M.Sc. Thesis
Sharif University of Technology
;
Nobakhti, Amin
(Supervisor)
Abstract
In continous chemical process, disturbances usually propagate along the process. This project describes a data-driven method for identifying the direction of propagation of disturbances using historical process data. The concept is the application of Transfer Entropy, a method based on the conditional probability density functions that measures directionality of variation. For demonstration purposes the transfer entropy method is used to isolate the root-cause of the disturbance in the Tennassee Eastman benchmark process
Disturbance Reduction Servo Motor Controller Design and Implementation
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
The servomechanisms have wide industrial application such as robotics, Computer Numerical Control (CNC) machines, automated manufacturing and solar tracking. Several methods have already been proposed for servo motor control that the most important of them are Proportional Integral Derivative (PID), H2/H--, intelligent based controllers, and model predictive control. Problem specifications and user requirements, will determine the appropriate approach in each case. The aim of this thesis is construction of a real-life camera stabilizer to be used in the motion picture industry. Effects of base movement on the performance should be decreased by choosing appropriate sensors and control...
Optimization of Sparse Control Structures in Multivariable Systems
, Ph.D. Dissertation Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
In this thesis, the optimal control structure selection and design of sparse multi-variable control systems is addressed. A fundamental challenge which frequently emerges in engineering, social, and economic sciences, is the optimal selection of a subset of elements, in order to maximally fulfil a design objective. In practice, it is required to solve this underlying selection problem in conjunction with a non-linear or non-convex optimization which is designed to ensure desired performance. The requirement to solve these two problems simultaneously is what makes it inherently difficult; one which has thus far eluded efforts to develop a systematic means of determining its solution. In spite...