Loading...
Search for:
molavi-kakhki--amin
0.112 seconds
Total 299 records
Study of the Effect of Surfactant and Fe Concentration on the Size and Physical Properties of Magnetic Fe-Au Core-Shell Nano Particles, Synthesized Via Reverse Nicelle
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor) ; Abachi, Parvin (Supervisor)
Abstract
The aim of this research is to study the effect of surfactant type and the concentration reactants on the size, shape and magnetic properties of iron-gold core-shell magnetic nanoparticles (NPs) useable for biomedical application. The reverse micelle procedure was employed to synthesize iron NPs using two surfactants of CTAB and SDS. A gold shell with a thickness in the range of 10 to 40 nm was induced by reverse micelle method in order to prevent oxidation of the iron core. The size and morphology of NPs were studied by transition electron microscopy (TEM). It was found that the size of NPs increases by the increasing the reactants concentration while the morphology of the NPs was not...
Synthesis and Characterization of Chitosan-Modified Metal-Organic Framework to Remove Contaminants from Aquatic Environment
, M.Sc. Thesis Sharif University of Technology ; Hamzehluyan, Tayebeh (Supervisor) ; Shojaei Segherloo, Akbar (Supervisor) ; Molavi, Hossein (Co-Supervisor)
Abstract
In the present work, a series of nanohybrids based on ZIF-8 as a physicochemical stable metal-organic framework (MOF) and different amounts of Chitosan (CS) (0.5–15 wt%) were synthesized and used as adsorbents for anionic (Congo Red, CR) and cationic (malachite green, MG) dyes from contaminated water in single and binary dye solutions. The single adsorbents and their nanohybrids were characterized by FESEM, FTIR, XRD, TGA, BET, and zeta potential measurements. The experimental adsorption results displayed that the synthesized nanohybrids presented higher adsorption capacity for anionic dyes compared to cationic dyes in both single and binary dye solutions. It was deduced that the...
Fractional order model reduction approach based on retention of the dominant dynamics: Application in IMC based tuning of FOPI and FOPID controllers
, Article ISA Transactions ; Volume 50, Issue 3 , July , 2011 , Pages 432-442 ; 00190578 (ISSN) ; Haeri, M ; Sharif University of Technology
2011
Abstract
Fractional order PI and PID controllers are the most common fractional order controllers used in practice. In this paper, a simple analytical method is proposed for tuning the parameters of these controllers. The proposed method is useful in designing fractional order PI and PID controllers for control of complicated fractional order systems. To achieve the goal, at first a reduction technique is presented for approximating complicated fractional order models. Then, based on the obtained reduced models some analytical rules are suggested to determine the parameters of fractional order PI and PID controllers. Finally, numerical results are given to show the efficiency of the proposed tuning...
Temperature control of a cutting process using fractional order proportional-integral-derivative controller
, Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME ; Volume 133, Issue 5 , March , 2011 ; 00220434 (ISSN) ; Haeri, M ; Sharif University of Technology
2011
Abstract
In this paper, the fractionalized differentiating method is implemented to reduce commensurate fractional order models complexity. The prominent properties of this method are its simplicity and guarantee of preserving the stability of a specific class of fractional order models in their reduced counterparts. The presented reduction method is employed in simplifying complicated fractional order controllers to a fractional order PID (FOPID) controller and proposing tuning rules for its parameters adjustment. Finally, the efficiency of the FOPID tuning rule obtained based on the proposed reduction method is shown in the temperature control of a cutting process
The minimal state space realization for a class of fractional order transfer functions
, Article SIAM Journal on Control and Optimization ; Volume 48, Issue 7 , 2010 , Pages 4317-4326 ; 03630129 (ISSN) ; Haeri, M ; Sharif University of Technology
2010
Abstract
In this paper, the minimal state space realization of a fractional order transfer function is investigated in the sense of inner dimension both for commensurate and incommensurate cases. It is shown that while the traditional tools are applicable to check the minimality of a commensurate realization, there is no specific procedure to be certain about the minimality of incommensurate realizations. In this regard, the necessary and sufficient conditions are obtained for a specific class of fractional order transfer functions by which one can verify the existence of minimal realizations with inner dimension 2. Furthermore, a transformation is introduced through which all these realizations can...
Model reduction in commensurate fractional-order linear systems
, Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 223, Issue 4 , 2009 , Pages 493-505 ; 09596518 (ISSN) ; Haeri, M ; Sharif University of Technology
2009
Abstract
In this paper, some commonly used model reduction methods for integer-order systems are employed to approximate commensurate fractional-order linear systems. In comparison with the original system, the approximating model possesses a smaller inner dimension, while its fractional order is the same as that of the original system. The applied methods fall into the global reduction category, such as direct truncation and singular perturbation methods, and into the local reduction category, such as Pade approximation, partial realization, shifted Pade approximation, and rational interpolation methods. The applicability of these methods is illustrated by approximating a sample high-dimensional,...
Presenting a rule based loan evaluation expert system
, Article 4th International Conference on Information Technology-New Generations, ITNG 2007, Las Vegas, NV, 2 April 2007 through 4 April 2007 ; 2007 , Pages 495-502 ; 0769527760 (ISBN) ; 9780769527765 (ISBN) ; Daneshvar Kakhki, M ; Sharif University of Technology
2007
Abstract
A core process in investment banks is evaluation of loan requests. In this paper we have presented the development of a rule based expert system for evaluation of loan request. The purpose of system is to evaluate the loan request and do some sensitivity analyses on the evaluation result to find the critical criteria. To achieve this purpose, Inference engine works both forward (evaluation) and backward chaining (sensitivity analysis). This system is designed for the Iranian bank of Industry and Mine. © 2007 IEEE
Fractional Simplification of Linear Fractional Order Models
, Ph.D. Dissertation Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
In recent years, increasing attention has been paid to the fractional calculus as a powerful tool for more precise modeling of real world phenomena. Also, it has been shown that using this tool in designing control systems results in controllers that are more efficient in comparison with their traditional integer order counterparts. In spite of the advantages of fractional order models, the difficulties in the implementation of this type of models are still the main concern of the control system community. Clearly, as a model becomes simpler, its implementation becomes more convenient. Therefore, one way to rectify the implementation problems is to model the intended system as simple as...
Estimation of the order and parameters of a fractional order model from a noisy step response data
, Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME ; Vol. 136, issue. 3 , May , 2014 ; ISSN: 00220434 ; Tavazoei, M. S ; Sharif University of Technology
2014
Abstract
This paper deals with integral based methods to estimate the order and parameters of simple fractional order models from the extracted noisy step response data of a process. This data can be obtained from both open-loop and closed-loop tests. Numerical simulation results are presented to verify the robustness of these proposed methods in the presence of the measurement noise
Compensation by fractional-order phase-lead/lag compensators
, Article IET Control Theory and Applications ; Volume 8, Issue 5 , 2014 , Pages 319-329 ; ISSN: 17518644 ; Tavakoli Kakhki, M ; Sharif University of Technology
2014
Abstract
This study deals with a generalised version of lead/lag compensators known as fractional-order lead/lag compensators. Exact and simple formulas are found for designing this introduced type of fractional-order compensators in order to provide the required magnitude and phase at a given frequency. Also, the region in the phase-magnitude plane, which is accessible by these compensators, is analytically found. Moreover, numerical examples and experimental results are presented to show the applicability of the achievements of this study in control system design
Proportional stabilization and closed-loop identification of an unstable fractional order process
, Article Journal of Process Control ; Vol. 24, Issue. 5 , 2014 , pp. 542-549 ; ISSN: 09591524 ; Tavazoei, M. S ; Sharif University of Technology
2014
Abstract
This paper deals with proportional stabilization and closed-loop step response identification of the fractional order counterparts of the unstable first order plus dead time (FOPDT) processes. At first, the necessary and sufficient condition for stabilizability of such processes by proportional controllers is found. Then, by assuming that a process of this kind has been stabilized by a proportional controller and the step response data of the closed-loop system is available, an algorithm is proposed for estimating the order and the parameters of an unstable fractional order model by using the mentioned data
Minimal realizations for some classes of fractional order transfer functions
, Article IEEE Journal on Emerging and Selected Topics in Circuits and Systems ; Volume 3, Issue 3 , 2013 , Pages 313-321 ; 21563357 (ISSN) ; Tavakoli Kakhki, M ; Sharif University of Technology
2013
Abstract
It has been known that finding a minimal pseudo state space realization for a fractional order transfer function is helpful in circuitry implementation of such a transfer function with the minimum number of fractional capacitors. Considering this importance, the present paper deals with finding minimal realizations for some classes of fractional order transfer functions. To this end, at first some upper bounds are obtained for the minimal inner dimension of a fractional order transfer function. By considering these upper bounds and also the lower bounds, previously presented in literature, the minimal inner dimension is exactly found for some classes of fractional order transfer functions....
Static feedback versus fractionality of the electrical elements in the Van der Pol circuit
, Article Nonlinear Dynamics ; Volume 72, Issue 1-2 , 2013 , Pages 365-375 ; 0924090X (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
2013
Abstract
In this paper, it is shown that by benefiting from a static feedback control signal it is possible to reduce the effect of fractionality of the electrical capacitors on the amplitude of the oscillations produced by a Van der Pol circuit. The averaging method is used in this paper for the behavior analysis of the approximated responses of the under study circuits. Numerical simulation results are presented to confirm the effectiveness of the proposed control technique
Mixed-matrix composite membranes based on uio-66-derived MOFs for CO 2 separation
, Article ACS Applied Materials and Interfaces ; Volume 11, Issue 9 , 2019 , Pages 9448-9461 ; 19448244 (ISSN) ; Shojaei, A ; Sharif University of Technology
American Chemical Society
2019
Abstract
We demonstrated a novel mixed-matrix composite membrane (MMCM) based on acrylated polyurethane (APU) and UiO-66 nanoparticles to separate CO 2 /N 2 mixture. UiO-66 and functionalized UiO-66 including NH 2 -UiO-66 and glycidyl methacrylate (GMA)-UiO-66 were loaded into APU/2-hydroxyethyl methacrylate (APUH) matrix at variable concentrations between 3 and 30 wt %. APUH/GMA-UiO-66 MMCMs exhibited strong adhesion with a support layer of polyester/polysulfone, which was not deteriorated after immersion in water for a long time (20 days). Incorporation of UiO-66 and its functionalized forms increased simultaneously permeability and CO 2 /N 2 selectivity, which were indeed superior in comparison...
Study on control input energy efficiency of fractional order control systems
, Article IEEE Journal on Emerging and Selected Topics in Circuits and Systems ; Volume 3, Issue 3 , July , 2013 , Pages 475-482 ; 21563357 (ISSN) ; Haeri, M ; Tavazoei, M. S ; Sharif University of Technology
2013
Abstract
Control input energy efficiency is an important issue which should be considered in designing any control system. Due to the importance of this subject, in the present paper fractional order control systems are studied in the viewpoint of control input energy efficiency. In this study, the divergent terms of the control input energy function of fractional order control systems are obtained. It is shown that these terms have a significant role in the amount of the energy injected to the plant by the controller. Finally, two examples are provided to demonstrate the usefulness of the presented results in the paper
Notes on the state space realizations of rational order transfer functions
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 58, Issue 5 , 2011 , Pages 1099-1108 ; 15498328 (ISSN) ; Haeri, M ; Tavazoei, M. S ; Sharif University of Technology
2011
Abstract
In this paper, the concept of minimal state space realization for a fractional order system is defined from the inner dimension point of view. Some basic differences of the minimal realization concept in the fractional and integer order systems are discussed. Five lower bounds are obtained for the inner dimension of a minimal state space realization of a fractional order transfer function. Also, the concept of optimal realization, which can be a helpful concept in practice, is introduced for transfer functions having rational orders. An algorithm is suggested to obtain the optimal realizations of rational order transfer functions. The introduced concept might be used to get minimal...
Parameter and order estimation from noisy step response data
, Article IFAC Proceedings Volumes (IFAC-PapersOnline) ; 2013 , Pages 492-497 ; 14746670 (ISSN) ; 9783902823274 (ISBN) ; Tavazoei, M. S ; Mesbahi, A ; Sharif University of Technology
2013
Abstract
In this paper, two integral based methods are proposed to estimate the order and the parameters of simple fractional order models from the noisy step response data. Numerical simulation results show the efficiency of the proposed methods in the presence of the measurement noise
Simple fractional order model structures and their applications in control system design
, Article European Journal of Control ; Volume 16, Issue 6 , 2010 , Pages 680-694 ; 09473580 (ISSN) ; Haeri, M ; Tavazoei , M. S ; Sharif University of Technology
2010
Abstract
In this paper, firstly a four-parameter fractional order model structure is introduced to approximate processes having S-shaped step responses. Three different strategies are presented in order to determine the parameters of the proposed model. In a special case where the proposed model is not satisfactory, another fractional order model structure with five free parameters is introduced to improve the model approximation. Also in this case, a procedure is provided to estimate the parameters of the introduced five-parameter model. Then, some common classical integer order control design approaches are modified or extended to their fractional order counterparts in order to incorporate the...
Over-and under-convergent step responses in fractional-order transfer functions
, Article Transactions of the Institute of Measurement and Control ; Volume 32, Issue 4 , June , 2010 , Pages 376-394 ; 01423312 (ISSN) ; Haeri, M ; Tavazoei, Mohammad Saleh ; Sharif University of Technology
2010
Abstract
In this paper we highlight a remarkable difference between the step responses of a classical second-order transfer function and its fractional-order counterpart. It can be easily shown that the step response of a stable classical second-order transfer function crosses its final value infinitely over time. In contrast, it is illustrated here that the step responses of a fractional-order counterpart of the classical second-order model possess only a finite number of such crossovers. In other words, for such a system one can find a specific time instant after which the step response is over or under-convergent to its final value. This property interprets some phenomena observed in the...
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...