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ebrahimi--mojtaba
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A ZVS-resonant bifilar drive circuit for SRM with a reduction in stress voltage of switches
, Article International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2011 and Electromotion 2011 Joint Conference, Istanbul ; 2013 , Pages 125-128 ; 9781467350037 (ISBN) ; Najmi, V ; Ebrahimi, S ; Oraee, H ; Sharif University of Technology
2013
Abstract
Switched Reluctance Motors (SRMs) are widely used in high-speed and low voltage applications because of their attractive features such as robustness and simplicity. No winding on the rotor of this type of motors allows reaching high speed which is desired for many applications. Drive circuits of SRMs also play an important role in their performance and operation. In this paper, a new bifilar drive circuit for this type of motors has been proposed. This novel configuration has been tested and investigated by PSIM software. Results show that the new bifilar drive circuit highly reduces the voltage stresses on semiconductor switches, and also considerably reduces the switching losses which are...
Preparation, Surface Modification and Application of Nanocomposite Membranes Based on Transition Metals- Dichalcogenide Nanoparticles in Forward Osmosis Desalination Process
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor) ; Ahadian, Mohammad Mahdi (Supervisor) ; Amini, Mojtaba (Supervisor)
Abstract
Different parts of this research are focused on developing FO membranes and improving their performance. For this purpose, thin film composite (TFC) membranes with fixed composition of polyethersulfone/polyamide (PES/PA) have been used to investigate the effect of nanocomposites containing transition metal dichalcogenides (TMDs) on their performance. The support layer in all cases is PES, which is prepared through the phase inversion process and does not contain any nanofillers. The modification process takes place in the polyamide layer by dispersing the desired nanoparticles in the aqueous monomer solution necessary to form this active layer. Identification and characterization of...
Energy management of smart home considering residences' satisfaction and PHEV
, Article 2018 International Conference on Smart Energy Systems and Technologies, SEST 2018, 10 September 2018 through 12 September 2018 ; 2018 ; 9781538653265 (ISBN) ; Shokri Gazafroudi, A ; Corchado, J. M ; Ebrahimi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Regarding the increasing number of electrical devices in the smart homes that leads to increase in total electricity consumption and cost, it is essential to use energy management methods to reduce the electricity cost. However, this can cause resident's dissatisfaction. Hence, it is important to define a method in which cost and dissatisfaction be optimized simultaneously. Among different services, an electric vehicle is the one that can be used as an energy storage system, so it can reduce the daily cost despite of increasing the total energy consumption. In this paper, we study the effect of the EV on the cost and dissatisfaction in our proposed method. © 2018 IEEE
Measured impact of different back-off points and cooling methods on pulse-to-pulse stability and sidelobe level of a high-power solid-state amplifier
, Article IET Radar, Sonar and Navigation ; Volume 14, Issue 2 , 2020 , Pages 335-340 ; Khodarahmi, E ; Ebrahimi, E ; Ahmadi, B ; Jalali, M ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Using solid-state power amplifiers for next generation of weather radars becomes feasible by pulse compression techniques. In this study a 1.5 kW solid-state power amplifier (transmitter) for C-band weather radars is designed and fabricated by GaN high electron mobility transistor (HEMT) technology. An experimental setup based on heterodyne receiver with 16-bit digitiser is developed to investigate the behavior of the power amplifier under different cooling methods and back-off points. Several measurements with shaped LFM pulse show an approximately identical pulse to pulse (P2P) stability for 3 dB compression, P1dB and 2 dB back-off points while the best sidelobe level (SLL) is achieved for...
Synthesis and Study of Catalytic Activity of Iron (III)-bis(2-oxazolinyl) Methane complex by Urea Hydrogen Peroxide in Oxidation of Sulfides
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
Considerable effort has been directed in recent years towards the transition metal complex catalyzed oxidation of organic compounds. Herein the synthsis of the iron complex of bis(oxazoline) ligand as a novel catalyst is reported, and the catalytic activity of this complex in oxidation of sulfides is investigated. Bis(2-oxazolynil)methane as ligand is prepared by condensation of diethylmalonate with 2-aminoethanole in 1:2 molar ratio and finally corresponding complex is synthesized by the reaction between FeCl3.6H2O and Bis(2-Oxazolynil)methane in 1:1 molar ratio. The complex is characterized by using IR, UV-Vis, cyclic voltametery, conductometery and elemental analysis data. Moreover,...
Design of a Low Noise Amplifier without On-Chip Inductor
, M.Sc. Thesis Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
In this project a wide-band inductorless Low Noise Amplifier (LNA) has been designed using 0.18 micrometer CMOS technology. The specification of this amplifier has been explored in frequency band of 330MHz to 10GHz. Wide-band input and output impedance matching, low Noise-Figure (NF), reasonable voltage gain and low power consumption are the main challenges of Low Noise Amplifier design. Without using an inductor a better overall performance of LNA in a wide frequency band as well as a lower chip area has been achieved. In this design a novel noise cancellation technique in common-gate topology has been used for lowering the Noise Figure of the LNA. Group Delay of the designed LNA, which is...
Synthesis, Structure and Catalytic Application of Mn, Fe and Mo Complexes with Schiff base and Oxazoline ligands and Theoretical Mechanistic Studies on the Role of Heme and non-Heme Iron(IV)-Oxo Species in Hydroxylation and Epoxidation Reactions
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
The first part of this thesis describes the synthesis and characterization of several Mn, Fe and Mo complexes containing tridentate Schiff base and oxazoline ligands and their reactivities as catalysts in the oxidation of organic compounds like olefins and sulfides, as well. The crystal structures of newly prepared cis-dioxo-bis[2-(2′-hydroxyphenyl)-oxazolinato]molybdenum(VI), cis-[MoO2(phox)2] and (N-hydroxyphenyl-salicylidenamine)(acetylacetonato)ethanol iron(III), [FeIII(N-OPh-sal)(acac)EtOH] complexes have been described by X-ray crystallography. Due to the difficulties in the preparation of suitable single crystals of novel...
Designing and Fabricating the Active Phase Shifter
, M.Sc. Thesis Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
In this project, issues related to designing and fabricating active phase shifter blocks on the silicon substrate have been examined. Phase shifter circuits are designed in a way that have the most bandwidth and the less sensitivity to process characteristics changes and environmental conditions. The purpose of this research, is designing an active 6 bits phase shifter. The active phase shifter synthesizes the required phase using a phase interpolation process by adding quadrature phased input signals. It uses a new quadrature all-pass filter for quadrature signaling with a wide bandwidth. Also substitute structure has been suggested to this filter which is the main block in determining...
Wideband Frequency Synthesizer for Digital Video Tuners
, Ph.D. Dissertation Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
Integration of radio transceivers results in developing low power low cost wireless systems and allows delivery of multimedia contents to battery-powered mobile terminals. Portable reception of digital video for hand-held devices is one of the applications, for which, some telecommunications standards have been developed in the recent years. This research deals with the integrated implementation of the radio frequency parts of the digital video receiver, especially the frequency synthesizer. The key aspects of the digital video reception system are the required signal to noise ratio, which is relatively high, wide band input signals and strong interferers in the receiving band.
In...
In...
Design and Fabrication of RFID Front END Transceiver single chip with 2.5W Output Power
, Ph.D. Dissertation Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
This thesis deals with the front-End of an Integrated RFID Reader operated in 860MHz to 960MHz, which integrates a RF transceiver including PA, LNA and Mixer. In the receiver part, a power amplifier was fabricated and measured and in the transmitter part, LNA and Mixer were designed. There is a growing interest in utilizing CMOS technologies for RF power amplifiers (PAs). Although several advances have been made recently to enable full integration of PAs in CMOS, it is still among the most difficult challenges in achieving a truly single-chip radio system in CMOS. This is exacerbated by supply voltage reduction due to CMOS technology scaling and on-chip passive losses due to the conductive...
Synthesis and Study of Catalytic Reactivity Oxo Vanadium (IV)& (V) Complexes with N,N'-Ethylenebis(Salicylimine)Ligand in Oxidation of Sulfides and Epioxidation of Olfins by Urea Hydrogen Peroxide (UHP) and Tert-Butyl Hydroperoxide (TBHP)
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
The selective oxidation of sulfides to sulfoxides is an important method in organic synthesis because sulfoxides are useful synthetic intermediates for the construction of various chemically and biologically significant molecules. To date, the most important method of preparation involves the oxidation of sulfides. Various oxidizing agents are used for this purpose. Oxovanadium(IV)(Salen) and oxovanadium(V)(Salen)Cl were synthesised and screened in the vanadium-catalysed oxidation of sulfides to solfuxides with urea hydrogen peroxide(UHP) as terminal oxidant. Both complexes showed good activity and selectivity trough the catalytic reaction.characterized by elemental analyses, IR, 1H and 13C...
Design and Implementation of Fully Integrated Frequency Synthesizer for Biomedical Applications
, M.Sc. Thesis Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
Fully integrated frequency synthesizer is one of the important system-on-chips building blocks. Among this circuit’s remarkable applications, Bioelectronics field is very common. In these applications, advanced microelectronic circuits are used in order to diagnosis and treatment of diseases. The aim of this thesis is design and implementation a wideband frequency synthesizer in a 0.18um CMOS technology. The main usage of this circuit is in a fully integrated implantable biomedical sensory chip. This circuit generates two necessary local signals in sensory chip to stimulus cells and process the information.
Frequency synthesizer is based on phased locked loop (PLL) circuit and produce...
Frequency synthesizer is based on phased locked loop (PLL) circuit and produce...
Synthesis and Characterization of a novel Ruthenium(II) Complex With Bidentate O,N-donor OxazolineLigand and Study of Catalytic Oxidation of Sulfides and Alkanes
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
The 2-(2′-hydroxyphenyl)-oxazoline ligand (Hphox) is generated from 1:1 condensation of methyl salicylate with 2-aminoethanol. Novel [Ru(Hphox)2(H2O)2] (Hphox = 2-(2′-hydroxyphenyl)-oxazoline ) complex has been synthesized and characterized by physic-chemical methods. Oxidation of sulfides catalyzed by the mixed-ligand ruthenium(II) complex [Ru(Hphox)2(H2O)2]using urea-hydrogen peroxide (UHP) as oxidant was investigated under mild condition within 1 h. The results showed that mixed-ligand ruthenium(II) complex was effective catalyst in oxidation of sulfides in whichsulfoxideswere the only products. Using this catalytic system in the oxidation of alkanes, ketones were obtained as the main...
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
Inert gold become catalytically active when dispersed in the form of nanoparticles. Isolated gold nanoparticles have demonstrated high catalytic activity for both oxidation and reduction reactions. In order to obtain high catalytic activity, gold nanoparticles are generally dispersed on support materials, among which oxides are commonly used. However, a substantial decrease in activity and selectivity of the immobilized catalysts is frequently observed due to the heterogeneous nature of these support materials in reaction media. In the course of our study on the metal-based catalysis for synthesis of organic compounds, we herein report that rod-shaped Au nanoparticles in aqua solution...
Preparation of Heterogeneous Catalysts by Immobilization of Molybdenum and Manganese-shiff Base Complexes into the Nanopores of Zeolite and SBA-15
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
This thesisconsiders new fundamental approaches to yield heterogeneous catalysts in to three sections. The first section described the immobilization of the molybdenum-Schiff base complexes in pores of SBA-15 in two different methodologies depending on the actual structure of the complexes., (i) stepwise formation of the complex by initial covalent anchoring of one of the components and consecutive solid phase synthesis consisting of the condensation of the other components of the salen complex (iii) one-step complex immobilization by covalent binding through the ligand.Based on the first methodology, we report the preparation of ordered mesoporous silica SBA-15 containing a molybdenum...
Synthesis and Characterization of Various Transition Metal Complexes and the Application in Oxidation, Heck, Suzuki, Sonogashira and Olefin Metathesis
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In nature, catalysis is of vital importance in a wide variety of biochemical processes catalyzed by metalloenzymes. The functions performed by the metalloenzymes and their significance have inspired a range of biomimetic studies, and intense efforts have been concentrated on the synthesis of low molecular weight complexes to model the spectroscopic features of such enzymes. Concomitantly, a challenging frontier in the field of biomimetic chemistry is the development of highly reactive model compounds that are able to effect rapid and selective substrate conversion. Some important catalytic transformations that have gained attention in recent years involve the carbon-carbon coupling, olefin...
Synthesis of Core-Shell Nanoparticles Supported Iron and Vanadium Schiff Base and Their Application as a Catalyst for Oxidation of Sulfides, Alcohols and Olefins
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this work, synthesized Fe3O4 magnetic nanoparticles andcoated with SiO2 to prepare magnetic core-shell nanoparticles. Then immobilized Schiff baseof iron and vanadium complexes on magnetic core-shell nanoparticles was prepared as a recoverable magnetic nano catalysts. These catalysts were named Fe3O4@SiO2@L1@Fe, Fe3O4@SiO2@L2@Fe and Fe3O4@SiO2@L3@V. Furthermore,olefines epoxidation, sulfides and alcohols oxidation were studied with using iron and vanadium magnetic nano catalysts. The supported catalysts were characterized by atomic absorption, FT-IR and UV–Vis spectra.The catalytic performance of the synthesized iron catalyst was tested for the epoxidation of cyclohexene, styrene and...
Synthesis of Metal-Organic Frameworks and Self-supported Coordination Polymers of Transition Metals with Catalytic Potential as Template for Supported Pd Nanoparticles and Preparation of Metal Oxide Nanoparticles for Olefin Epoxidation and C-C Coupling Reactions
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this research, synthesis of new heterogeneous catalysts has been studied. These catalysts were prepared in three different areas of the synthesis of coordination polymers and metal-organic frameworks, supported palladium nanoparticles on these polymers, and production of metal oxide nanoparticles. At first, metal organic frameworks of cobalt and manganese transition metals were synthesized through hydrothermal method. In order to prepare these frameworks, 1,4-benzenedicarboxylic acid (terephthalic acid) and 2-amino-1,4-benzenedicarboxylic acid ligands were utilized as spacer ligands. X-ray analysis indicated that the structure of polymers is composed of secondary building units (SBUs) of...
Heterogenization of Ionic Complexes of Mo(VI) with Sulfonated Schiff Base Ligands on the Polysiloxane as Support for Catalytic Epoxidation of Olefins
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this project a new molybdenum (VI) complex with tetradentate Schiff base ligand which was soluble in water was synthesized and characterized. In the first step of ligand synthesis, the reaction was performed between salicylaldehyde and aniline, and then used concentrated sulfuric acid for sulfonation. In the next step 5- sulfosalicylaldehyde sodium salt was formed by removing of aniline with heating and using sodium carbonate. In the presence of ethylendiamine and bis (acetylacetonato) dioxomolybdenum(VI) the final product, cis-dioxo sodium (N,N-bis (5-sulfonatosalicyldene)1,2-diaminoethane) molybdenum (VI) complex was synthesized. The complex was characterized by (CHN) elemental...
Synthesis and Characterization of Cis-dioxomolybdenum(VI) Complex with an ONOtype Tridentate Schiff base Ligand and its Application as a Catalyst for Epoxidation of Olefinsin Water
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
New dioxomolybdenum(VI) complex has been synthesized by reacting N-hydroxyphenyl-[5-(triphenylphosphonium)methyl]salicylideneamine chloride (PPh3-H2sap) as a water soluble ligand and [MoO2(acac)2] in ethanolic solution. The water soluble ligand (PPh3-H2sap) was prepared by reaction of 2-aminophenol with (3-formyl-4-hydroxybenzyl)triphenylphosphonium chloride as a water solublesalicylaldehyde derivative. The resulting complex with the formula [MoO2(PPh3-H2sap)(EtOH)] which contains an ethanol molecule in sixth site of coordination, was characterized by elemental analyses, 1H NMR,31P NMR, IR and UV-Vis spectroscopic studies. This complex was tested as a catalyst for the homogeneous...