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Direct Speed Control of Permenant Magnet Synchronous Machine
, M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad (Supervisor)
Abstract
Accurate and fast position controlling is an important issue in today’s industrial needs. Drives used for position control require fast dynamics on speed control. Cascade linear controllers have sluggish response due to bandwidth limitations on speed and current loop. These structures limit the dynamics above all in high power applications where the switching frequency is low. In this thesis, deadbeat direct speed control is proposed, which overcomes limitations by cascade loops resulting in high-speed control dynamics. This approach uses a model of the plant to generate the control signals. According to measured speed and currents, the controller specifies the best voltage vector in order...
Simulation and Investigation of Mechanical Behavior of Non Pneumutic Tires
, M.Sc. Thesis Sharif University of Technology ; Arghavani Hadi, Jamal (Supervisor)
Abstract
Due to the relatively high freedom of selection of materials associated with a simple manufacturing method, a nonpneumatic tire (NPT) can be manufactured with low viscoelastic energy loss material. NPTs consisting of flexible spokes and the shear band are still at an early stage of research and development. An optimization study of NPTs’ geometry needs to be conducted, which is the objective of this thesis. Parametric studies and design of experiments (DOE) of an NPT are conducted with a hyper-viscoelastic finite element (FE) model to determine the effects of four design variables on rolling resistance, contact pressure and vertical deflection. Considering vehicle load carrying capacity and...
Analysis of modal reflectivity of optical waveguide end-facets by the characteristic green's function technique
, Article Journal of Lightwave Technology ; Vol. 32, Issue. 6 , 2014 , Pages 1168-1176 ; ISSN: 07338724 ; Shishegar, A. A ; Faraji Dana, R ; Sharif University of Technology
2014
Abstract
A novel method for computation of guided mode reflectivity from optical waveguide end-facet is presented. The method is based on the characteristic Green's function (CGF) technique formulation combined with the complex images (CIs) method for dielectric planar waveguides. By separability assumption of the structure, a uniform and closed-form expression of spatial Green's function is obtained. Derived expression consists of discrete and continuous spectrum contributions which denote guided and radiation modes effects, respectively. Having a full-wave solution, efficient optimization procedure is then used to calculate the exact reflection coefficients of guided modes at the end-facets. To...
An efficient closed-form derivation of spatial green's function for finite dielectric structures using characteristic green's function-rational function fitting method
, Article IEEE Transactions on Antennas and Propagation ; Vol. 62, issue. 3 , 2014 , pp. 1282-1292 ; ISSN: 0018926X ; Shishegar, A. A ; Faraji-Dana, R ; Sharif University of Technology
2014
Abstract
A uniform and closed-form spatial Green's function for finite dielectric structures is derived by using a combination of the characteristic Green's function (CGF) and rational function fitting method (RFFM). Employing the concept of quasi leaky waves, CGF-RFFM represents both of the discrete and continuous spectrum contributions efficiently by using the modified VECTFIT algorithm. The method is examined for 2-D truncated dielectric slab while it can be implemented for 3-D structure straightforwardly. An error of less than 0.2% is achieved compared with the direct numerical integration of the spectral integral. The derived Green's function is exact for separable structures while it is...
Application of the characteristic green's function technique in closed-form derivation of spatial green's function of finite dielectric structures
, Article CEM 2013 - Computational Electromagnetics International Workshop ; number 6617132 , 2013 , Pages 54-55 ; 9781479914326 (ISBN) ; Shishegar, A. A ; Faraji Dana, R ; Sharif University of Technology
2013
Abstract
A closed-form spatial Green's function for finite dielectric structures is derived by using a combination of the characteristic Green's function (CGF) and rational function fitting method (RFFM). CGF-RFFM represents both of the discrete and continuous spectrum contributions efficiently by using the modified VECTFIT algorithm. To obtain more accurate results, reflection coefficient correction due to the surface waves (SWs) incident on the the end-facet is considered. The main advantage of this method lies in its speed as well as accuracy. Excellent agreements with the rigorous method of moments (MoM) are shown in several examples
Novel sulfobetaine-sulfonic acid-contained superswelling hydrogels
, Article Polymers for Advanced Technologies ; Volume 16, Issue 9 , 2005 , Pages 659-666 ; 10427147 (ISSN) ; Faraji Dana, S ; Zohuriaan Mehr, M. J ; Sharif University of Technology
2005
Abstract
Novel hydrogels based on zwitterionic monomer [3-(methacrylamido)propyl] dimethyl (3-sulfopropyl) ammonium hydroxide (MPDSAH) and a strong acid monomer (2-acrylamido-2-methylpropane sulfonic acid, AMPS) were synthesized through solution polymerization under normal conditions to achieve nearly quantitative gel yield. The structure of the gels was confirmed using infrared spectroscopy. Thermal properties were simultaneously studied by differential scanning calorimetry and thermogravimetric analysis (DSC/TGA). The effects of the polymerization variables on the swelling capacity of the products were investigated. It was found that, in a certain range of the monomers mol ratio, increase of AMPS...
Environmental parametric cost model in oil and gas EPC contracts
, Article Sustainability (Switzerland) ; Volume 10, Issue 1 , 2018 ; 20711050 (ISSN) ; Toutounchian, S ; Dana, T ; Abedi, Z ; Toutounchian, S ; Sharif University of Technology
MDPI AG
2018
Abstract
This study aims at identifying the parameters that govern the environmental costs in oil and gas projects. An initial conceptual model was proposed. Next, the costs of environmental management work packages were estimated, separately and were applied in project control tools (WBS/CBS). Then, an environmental parametric cost model was designed to determine the environmental costs and relevant weighting factors. The suggested model can be considered as an innovative approach to designate the environmental indicators in oil and gas projects. The validity of variables was investigated based on Delphi method. The results indicated that the project environmental management's weighting factor is...
Improvement and Expansion of Characteristic Green’s Function-Complex Images Method for Extraction of Green’s Function of Finite Dielectric Structures
, Ph.D. Dissertation Sharif University of Technology ; Shishegar, Amir Ahmad (Supervisor) ; Faraji-Dana, Reza (Co-Advisor)
Abstract
Finite dielctric structures are commonly used in optical devices, Microwave Integrated Circuitc (MICs) and printed antennas. To analyze these structures, full-wave analysis methods cannot be employed easily. They need huge computer resources and are time-consuming especially for electrically large structures. On the other hand, asymptotic techniques may not be exact enough for these structures. In this thesis, MPIE technique is chosen as an accurate and efficient technique for analyzing these structres. To use this technique, the magnetic vector potential and electric scalar potential are required. Uniform and closed-form spatial Green's function for finite dielectric structures is...
Magnetic carbon nanocomposite derived from waste tire rubber for atrazine removal from aqueous solutions
, Article Desalination and Water Treatment ; Volume 252 , 2022 , Pages 219-232 ; 19443994 (ISSN) ; Borghei, M ; Takdastan, A ; Javid, A. H ; Zazouli, M. A ; Sharif University of Technology
Desalination Publications
2022
Abstract
In this study magnetite nanoparticles (Fe3 O4) were synthesized and embedded in activated carbon (AC) derived from waste tire rubber to produce magnetic activated carbon. The atrazine (C8 H14 ClN5) adsorption was performed over (AC/Fe3 O4) nanocomposite in an aqueous solution and adsorp-tion isotherms and kinetics were determined. The effects of some parameters such as (pH, contact time, adsorbent dosage and initial pesticide concentration) were investigated. Characterization of nanocomposite was carried out by high-resolution scanning electron microscopy and transmission electron microscopy, X-ray powder diffraction, vibrating sample magnetometer, Brunauer–Emmett– Teller, Fourier-transform...