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    Synthesis of CaO Impregnated on Carbon Nano Tube for Biodiesel Production

    , M.Sc. Thesis Sharif University of Technology Malakootikhah, Mohammad (Author) ; Khorashe, Farhad (Supervisor) ; Tabatabaei, Meisam (Supervisor) ; Rashidi, Alimorad (Supervisor)
    Abstract
    In the current work, jatropha oil was studied in the hetrogenious solid catalytic transesterfication reaction. For this perpous, KOH/CNT catalyst which was prepared by dry impregnation method was used. SEM, XRD and TGA were applied for the catalyst characterization. The results showed that for the KOH/CNT catalyst, by increasing the loading of KOH, the activity of the catalyst increased and the most active catalyst was prepared by 20% loading of KOH. The optimum conditions for transesterfication reaction in the percense of this catalyst were: 4.7% catalyst weigth and the 24.5 molar ratio of methanol to oil and also the reaction time of 2 houres which the rate of reaction at this time is... 

    Kierkegaardian Faith: On The Subject of Faith and Her Hope

    , M.Sc. Thesis Sharif University of Technology Masoudi, Hamid (Author) ; Sefidkhoh, Meisam (Supervisor) ; Azadegan, Ebrahim (Supervisor)
    Abstract
    In this treatise, it will be shown that the subject of faith is the subject who loves God and in showing her love to God, she sacrifices her dearest things in the world. By doing that, she would free herself from everything that mind herself. She doesn’t do this action to be given a better reward by God. Her motivation for performing this action is nothing but love. Meanwhile, the subject of faith hopes God to respond to her love and engage in an I-Thou relationship with her. Now, her hope would be justified when God plays an active role in the world and admires her action, i.e., when eros can be attributed to God  

    Heidegger on Science and Tool (Emphasized on "Being and Time")

    , M.Sc. Thesis Sharif University of Technology Khalili, Mahdi (Author) ; Sefidkhosh, Meisam (Supervisor) ; Taghavi, Mostafa (Co-Advisor)
    Abstract
    This thesis is going to investigate the ontological foundation of Science and Tool. To this aim, it refers to Heidegger’s works especially the Being and time. Heidegger gets involve in analyzing Science in the Being and Time. He emphasizes on importance of establishment of a fundamental knowledge which should ontologically recognize basic concepts and methods of Sciences, to cause a real progress in sciences. Heidegger also asserts that the Mathematical interpretation of the world is not a fundamental, and it must be replaced with phenomenological interpretation, which clarifies the ontological foundation of the theoretical view, and regards to all aspects of world’s existence. In this... 

    Investigation of Equilibrium and Kinetics of Uranium Solvent Extaction by Cyanex 301 Using a Single Drop Column

    , M.Sc. Thesis Sharif University of Technology Bardestani, Raoof (Author) ; Samadfam, Mohammad (Supervisor) ; Torab-Mostaedi, Meisam (Supervisor)
    Abstract
    Uranium separation from other metals in ore and nuclear waste is one of the most important stagesin nuclear fuel cycling. Solvent extraction is the common method for uranium extraction that reagent plays important rule in this technique. In this investigation, uranium solvent extraction is carried out by Cyanex 301 as reagent from nitric acid. At beginning, equilibrium batch extraction was carried and the effect of parameters such as pH, reagent concentration, temperature, shaking time of two phases, volumetric ratio of two phases, diluent and nitric acid concentration on extraction was investigated and optimum value of parameters was calculated. Uranium concentration effect was also... 

    Study of Dispersed Phase Holdup and Slip Velocity in a Pulsed Disc and Doughnut Extraction Column

    , M.Sc. Thesis Sharif University of Technology Jalilvand, Hossein (Author) ; Outukesh, Mohammad (Supervisor) ; Torab Mostaedi, Meisam (Supervisor)
    Abstract
    Dispersed phase holdup has been measured in a 75 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phases flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis holdup in transition and emulsion regions. Empirical correlations are derived for prediction of... 

    Robots’ cooperation for finding a target in streets

    , Article 1st IFIP WG 1.8 International Conference on Topics in Theoretical Computer Science, 26 August 2015 through 28 August 2015 ; Volume 9541 , 2016 , Pages 30-43 ; 03029743 (ISSN) ; 9783319286778 (ISBN) Mehrizi, M. A ; Ghodsi, M ; Tabatabaei, A
    Springer Verlag  2016
    Abstract
    We study the problem of finding a target t from a start point s in street environments with the cooperation of two robots which have a minimal sensing capability; that is, robots do not know any information about the workspace including information on distances, edges, coordinates, angles etc. They just can detect the discontinuities in the visibility region of their location. The robots can detect target point t as soon as it enters their visibility region and have communication peripherals to send messages to each other. Our aim is to minimize the length of the path passed by the robots. We propose an online algorithm for robots such that they move in the workspace and find the target.... 

    Walking in streets with minimal sensing

    , Article Journal of Combinatorial Optimization ; Volume 30, Issue 2 , 2014 , Pages 387-401 ; ISSN: 13826905 Tabatabaei, A ; Ghodsi, M ; Sharif University of Technology
    2014
    Abstract
    We consider the problem of walking a robot in an unknown polygon called “street”, starting from a point (Formula presented.) to reach a target (Formula presented.). The robot is assumed to have minimal sensing capability in a way that cannot infer any geometric properties of the environment, such as its coordinates, angles or distances; but it is equipped with a sensor that can only detect the discontinuities in the depth information (or gaps). Our robot can also locate the target point (Formula presented.) as soon as it enters in robot’s visibility region. In addition, one pebble is assumed to be available to the robot to be used as an identifiable point and to mark any position of the... 

    Optimal strategy for walking in streets with minimum number of turns for a simple robot

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Vol. 8881, issue , 2014 , p. 101-112 Tabatabaei, A ; Ghodsi, M ; Sharif University of Technology
    2014
    Abstract
    We consider the problem of walking a simple robot in an unknown street. The robot that cannot infer any geometric properties of the street traverses the environment to reach a target t, starting from a point s. The robot has a minimal sensing capability that can only report the discontinuities in the depth information (gaps), and location of the target point once it enters in its visibility region. Also, the robot can only move towards the gaps while moving along straight lines is cheap, but rotation is expensive for the robot. We maintain the location of some gaps in a tree data structure of constant size. The tree is dynamically updated during the movement. Using the data structure, we... 

    Walking in streets with minimal sensing

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Chengdu ; Volume 8287 LNCS , 2013 , Pages 361-372 ; 03029743 (ISSN); 9783319037790 (ISBN) Tabatabaei, A ; Ghodsi, M ; Sharif University of Technology
    2013
    Abstract
    We consider the problem of walking in an unknown street, starting from a point s, to reach a target t by a robot which has a minimal sensing capability. The goal is to decrease the traversed path as short as possible. The robot cannot infer any geometric properties of the environment such as coordinates, angles or distances. The robot is equipped with a sensor that can only detect the discontinuities in the depth information (gaps) and can locate the target point as soon as it enters in its visibility region. In addition, a pebble as an identifiable point is available to the robot to mark some position of the street. We offer a data structure similar to Gap Navigation Tree to maintain the... 

    CRA based Control of non-minimum phase fractional order systems

    , Article Proceedings of the IEEE International Conference on Control Applications ; 2012 , Pages 855-858 ; 9781467345033 (ISBN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    2012
    Abstract
    In this paper the characteristic ratio assignment (CRA) method is employed to control transient response of a class of non-minimum phase fractional order systems. Since fractional order all-pass filter could not be realized, the fractional unstable zeros are converted to integer unstable zeros by multiplying complementary polynomials to numerator and denominator polynomials of system's transfer function. Doing so, the closed loop system would be an integer order all-pass filter multiple an all-pole fractional transfer function determined from CRA method. Computer simulation results are presented to illustrate the performance of the proposed method. m  

    Sensitivity analysis of CRA based controllers in fractional order systems

    , Article Signal Processing ; Volume 92, Issue 9 , September , 2012 , Pages 2040-2055 ; 01651684 (ISSN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    Elsevier  2012
    Abstract
    This paper focuses on robust performance analysis of a closed loop fractional order system through a sensitivity approach. The characteristic ratio assignment method is selected to attain a desired closed loop transient response. Then, we compute the sensitivity of such a desired transfer function with respect to its characteristic ratio and we explore its specifications. The relation between the coefficient diagram shape and the relative stability of the closed loop system is discussed. Also, the closed loop poles variations due to the changes in the characteristic ratios are investigated. Finally, we study a pseudo second order process to verify the robust performance of the characteristic... 

    CRA based control of fractional order systems subject to control signal constraint

    , Article International Conference on Control, Automation and Systems ; 2011 , Pages 268-272 ; 15987833 (ISSN) ; 9781457708350 (ISBN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    2011
    Abstract
    An approach is proposed to control transient response of fractional order systems with maximum permissible control signal. This goal is achieved using a newly suggested characteristic ratio assignment method. Based on the proposed method, the generalized time constant τ and the characteristic ratios including their pattern, an adjustable parameter β, and the product of two successive characteristic ratios ρ are determined such that predefined level of overshoot and time specification of closed loop step response are obtained while the control signal is confined to a pre assigned maximum magnitude. The raised issue is solved by defining an optimization problem in which the design parameters... 

    Design of fractional order proportional-integral-derivative controller based on moment matching and characteristic ratio assignment method

    , Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 225, Issue 8 , December , 2011 , Pages 1040-1053 ; 09596518 (ISSN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    2011
    Abstract
    This paper presents a new analytical method to design fractional-order proportional- integral-derivative (PID) controllers. The control parameters are calculated so that the closedloop system approximates a desired transfer function with transient response requirements. This function is determined based on the characteristic ratio assignment method. The control parameters are calculated by matching the first three moments of the closed-loop transfer function with the corresponding values of the desired system. Furthermore, to ensure closed-loop stability the proposed method is improved by using the shifted moments around the crossover frequency. Illustrative examples are given to show the... 

    Characteristic ratio assignment in fractional order systems (case 0 < v ≤ 0.5)

    , Article Transactions of the Institute of Measurement and Control ; Volume 35, Issue 3 , 2013 , Pages 360-374 ; 01423312 (ISSN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    2013
    Abstract
    Five different approaches are presented to assign characteristic ratios for commensurate fractional order systems having order in (0,0.5]. Through the indirect methods, a closed-loop or plant transfer function is converted to a commensurate order one with an order greater than 0.5 so that the previously designed CRA method by the authors is applicable. The first method among the proposed direct ones is based on increasing the order of the desired closed-loop transfer function that allows the employment of positive characteristic ratios. In the second method the closed-loop response is sped up by augmenting an appropriate zero. The final method uses negative characteristic ratios to reach the... 

    Characteristic ratio assignment in fractional order systems

    , Article ISA Transactions ; Volume 49, Issue 4 , October , 2010 , Pages 470-478 ; 00190578 (ISSN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    2010
    Abstract
    In this paper the characteristic ratios and generalized time constant are defined for all-pole commensurate fractional order systems. The sufficient condition for stability of these systems in terms of their characteristic ratios is obtained. Also an analytical approach for characteristic ratio assignment (CRA) to have a non-overshooting fast closed loop step response is introduced. The proposed CRA method is then employed to design a fractional order controller. Computer simulation results are presented to illustrate the performance of the CRA based designed fractional order controllers  

    Design and simulation of a novel integrated microfluidic chip for cell isolation and culture

    , Article Biotechnology and Applied Biochemistry ; Volume 70, Issue 3 , 2023 , Pages 1230-1244 ; 08854513 (ISSN) Tabatabaei, S.A ; Javaherchian, J ; Sharif University of Technology
    John Wiley and Sons Inc  2023
    Abstract
    The lab on a chip is utilized as a background and a substrate for creating a proper flow for cellular processes in medicine. In this study, the concepts of cell isolation and cell transfer methods have been discussed. After that, the device of separation and transfer systems has been designed, simulated, and verified by placing the frequency of particle separation and droplet formation, which is tried to introduce a new device that can be used in cellular studies. The optimal operation conditions for the problem have also been investigated. High separation efficiency (99%) could be achieved when the velocity of the sample inlet in the microchannel separator is 180 μm/s. Also, a microfluidic... 

    Characterization of Warm Mix Asphalt Containing Reclaimed Asphalt Binders

    , M.Sc. Thesis Sharif University of Technology Safazadeh, Faramarz (Author) ; Tabatabaei, Nader (Supervisor)
    Abstract
    Utilization of RAP in HMA reduces the initial costs, conserves natural sources and avoids disposal problems. Aged binder from RAP will have some effects on resultant binder. To date, solvent extraction and recovery is the only method that physically separates the RAP binder from the RAP aggregate for characterization. Time consuming for recovery, altering the physical properties of the recovered asphalt binder like binder hardening and the possibility that Asphalt binder is not completely extracted from the aggregate are the weak points of this method. Addressing the need for non-solvent based RAP binder characterization; procedures for low temperature characterization of RAP binder... 

    Path Planning in Unknown Environment with Minimal Sensing

    , Ph.D. Dissertation Sharif University of Technology Tabatabaei, Azadeh (Author) ; Ghodsi, Mohammad (Supervisor)
    Abstract
    In this research, path planning in unknown environment is considered. It is assumed that the robot’s sensors are the only tools to collect information from the scene. Volume of the information gathered from the environment depends on the capability of the sensor. So, a detour from the optimal path is unavoidable. In this research, the basic robot is equipped with a minimal sensing system that only detects the iscontinuities in depth information (gaps). We present some online search strategies that guide such a robot to navigate unknown streets from a start point s to reach a target point t. Then, we empower the robot by adding a compass to patrol more general classes of polygons. We present... 

    Characterization of RAP Binder and Warm Mix Asphalt Containing High RAP Percentage and Crumb Rubber

    , M.Sc. Thesis Sharif University of Technology Morsali, Atefeh (Author) ; Tabatabaei, Nader (Supervisor)
    Abstract
    Increased environmental concerns and high oil prices have encouraged highway agencies to maximize the use of recycled materials like Reclaimed Asphalt Pavements (RAP) in pavement construction. However, utilization of RAP has limited to low percentage, generally less than 25%. This is due aged, stiffer, and less strain tolerant asphalt binder in RAP. As the RAP proportion increases, a large amount of the aged binder will be introduced into the mixture. The excessive stiffness of HMA mixture tends to lead to less workable mixture. Studies were conducted to examine the effect of Sasobit on the workablility of high RAP mixtures. The results indicated while the utilization of Sasobit had improved... 

    Study of the Effects of Rrest Time and Loading Time on Viscoplastic Strain of Asphalt Concrtee

    , M.Sc. Thesis Sharif University of Technology Jahangiri, Behnam (Author) ; Tabatabaei, Nader (Supervisor)
    Abstract
    Asphalt concrete exhibits viscoelastic and viscoplastic behavior which is dependent on rate and temperature. To model this behavior, various mechanical modelshave been presented in which total strain, as the response of the applied stress, is decomposed by various researchers to recoverable and permanent strains.Accumulation and expansion of permanent response result in rutting which is a dominant and prevalent distress in hot mixed asphalt (HMA) in hot climates. The available models are not capable of accurately calculate the viscoplastic strain under cyclic loading.
    To close this gap, recovered viscoelastic strain at rest (unloading) period was introduced. This parameter accounted for...