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A dual-frame hybrid vector control of vector-modulated VIENNA I rectifier for unity power factor operation under unbalanced mains condition
, Article 2008 23rd Annual IEEE Applied Power Electronics Conference and Exposition, APEC, Austin, TX, 24 February 2008 through 28 February 2008 ; 24-28 Feb , 2008 , Pages 1402-1408 ; 10482334 (ISSN) ; 9781424418749 (ISBN) ; Moallem, A ; Zolghadri, M. R ; Ferdowsi, M ; Sharif University of Technology
2008
Abstract
In this paper, a dual-frame hybrid vector control (DFHVC) of vector-modulated VIENNA I rectifier is proposed. The purpose of this novel vector control system is not only to reduce second-order harmonic pulsation on the dc-side and consequently, to reduce odd-order harmonics on the ac side of VIENNA I rectifier under unbalanced mains, but also to ensure a near unity power factor operation of the rectifier under such circumstances. To serve this purpose, at first, a mathematical model of the VIENNA I rectifier under unbalanced condition is derived. In this model, besides demonstrating the nonlinear nature of the DC-link voltage dynamic, a new set of equations for current reference generation...
A DSP-based unified three phase/switch/level unity power factor rectifier using feedback linearization for DC-bus voltage control
, Article 7th International Conference on Power Electronics and Drive Systems, PEDS 2007, Bangkok, 27 November 2007 through 30 November 2007 ; 2007 , Pages 778-783 ; 1424406455 (ISBN); 9781424406456 (ISBN) ; Mirzaee Teshnizi, H ; Zolghadri, M. R ; Sharif University of Technology
2007
Abstract
In this paper, a unified hybrid vector control of vector modulated VIENNA I rectifier is presented. Feedback linearization technique is used for the DC-link voltage control. For this purpose, at first a mathematical model of the VIENNA I rectifier is derived. Using this model, it is shown that the dynamic of the rectifier falls into two categories; linear inner dynamic which consists of inner current control and neutral-point potential control and nonlinear outer dynamic which consists of the DC-link voltage control. Based on these facts, a hybrid vector control scheme meaning linear vector control of inner dynamics and nonlinear vector control of outer dynamic is devised. Simulations...
Performance-based seismic retrof itting of steel frames by the endurance time method
, Article Earthquake Spectra ; Volume 31, Issue 1 , February , 2015 , Pages 383-402 ; 87552930 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Earthquake Engineering Research Institute
2015
Abstract
The endurance time method (ET) is a dynamic analysis procedure in which intensifying dynamic excitations are used as the loading function. Seismic performance is evaluated over the entire range of equivalent seismic intensities of interest in each response history analysis, considerably reducing computational demand. In this paper, a general methodology for performance-based retrof itting of typical steel frames by the ET method is discussed. A baseline steel momentresisting frame is considered, and its seismic performance is evaluated by the ET method, considering viscous dampers and shear wall panels as strengthening alternatives. Each retrof itting option includes several design...
Attitude estimation and sensor identification utilizing nonlinear filters based on a low-cost MEMS magnetometer and sun sensor
, Article IEEE Aerospace and Electronic Systems Magazine ; Volume 30, Issue 12 , December , 2015 , Pages 20-33 ; 08858985 (ISSN) ; Shirazi, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
A combination of low-cost micro-electoro-mechanical sensors (MEMSs) and nonlinear attitude estimation algorithm techniques can provide an inexpensive and accurate system for navigation and attitude determination. The features of MEMSs are their light weight and small size; hence, the MEMSs have found significant attention in low-cost navigation and control systems [1]. A common disadvantage of these sensors is the significant errors that accompany the corresponding measurements. The accuracy obtained using MEMSs depends on a number of factors, such as scale factor, bias, and random noise corrections [2]. However, these low-cost sensors suffer from large noise and errors, making calibration...
Improved methodology for endurance time analysis: From time to seismic hazard return period
, Article Scientia Iranica ; Volume 19, Issue 5 , 2012 , Pages 1180-1187 ; 10263098 (ISSN) ; Estekanchi, H. E ; Vafai, A ; Sharif University of Technology
2012
Abstract
In the Endurance Time (ET) method, structures are subjected to a calibrated intensifying accelerogram and their performance is assessed based on their response at various equivalent intensity levels. Application of the ET method in performance-based design of structures has been studied by introducing a continuous performance target curve, which expresses the limit of the proper seismic performance of a structure along various times of the ET accelerogram. The correlation between time in the ET method and the return period for different structural periods is investigated. The procedure is based on the coincidence of response spectra obtained from the ET accelerogram at different times and...
Application of endurance time method in performance-based design of steel moment frames
, Article Scientia Iranica ; Volume 17, Issue 6 A , 2010 , Pages 482-492 ; 10263098 (ISSN) ; Estekanchi, H. E ; Vafai, A ; Sharif University of Technology
2010
Abstract
In this paper, application of the Endurance Time (ET) method in the performance-based design of steel moment frames is explained from a conceptual viewpoint. ET is a new dynamic pushover procedure that predicts the seismic performance of structures by subjecting them to a gradually intensifying dynamic action and monitoring their performance at various excitation levels. Structural responses at different excitation levels are obtained in a single time-history analysis, thus significantly reducing the computational demand. Results from three analyses are averaged to reduce the random scattering of the results at each time step. A target performance curve is presented based on the required...
Trimetallic Co-Ni-Mn metal-organic framework as an efficient electrocatalyst for alkaline oxygen evolution reaction
, Article Journal of Electroanalytical Chemistry ; Volume 922 , 2022 ; 15726657 (ISSN) ; Hatami, H ; Mirzaee Valadi, F ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Designing efficient and inexpensive catalysts toward the oxygen evolution reaction (OER) is vital for achieving sustainable and green hydrogen fuel production through water electrolysis. Herein, we have synthesized several bi- and trimetallic metal–organic frameworks (MOFs) composed of Co, Ni, and Mn metals and benzene-1,3,5-tricarboxylic acid linker. The MOFs were prepared via a simple hydrothermal method, and their electrocatalytic performances in alkaline OER were investigated. A battery of analytical techniques was employed to characterize the as-synthesized materials, including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM),...
Satellite Attitude Estimation Using MEMS
,
M.Sc. Thesis
Sharif University of Technology
;
Pourtakdoost, Hossein
(Supervisor)
Abstract
This thesis deals with the attitude estimation based on low cost sensor for a micro satellite in a circular, low earth orbit (LEO) and sensor calibration. With two body problem theory and Quaternion formulation, rotational motion is modeled. In addition gravity gradient effect is considered on satellite orbital elements. Using a 3-axis MEMS-based magnetometer and a sun sensor as two measurement systems, low cost attitude estimation is proposed. Bias and Scale factor are presented to model deterministic sensor error and white Gaussian noise to model stochastic sensor error. It is shown that by sensor calibration the estimation accuracy will improve. Non-linear estimation methods EKF, SRUKF...
NiSe2Nanoparticles supported on halloysite sheets as an efficient electrocatalyst toward alkaline oxygen evolution reaction
, Article Energy and Fuels ; Volume 36, Issue 23 , 2022 , Pages 14331-14340 ; 08870624 (ISSN) ; Hatami, H ; Mirzaee Valadi, F ; Akbarzadeh, E ; Sharif University of Technology
American Chemical Society
2022
Abstract
The oxygen evolution reaction (OER) with its sluggish kinetics has imposed a significant barrier to the sustainable and green generation of hydrogen fuel (via electrolysis of water) and the development of metal-air batteries. In this study, we report an efficient and novel OER electrocatalyst based on NiSe2nanoparticles (NPs) and the naturally abundant halloysite clay mineral. The NiSe2/halloysite nanocomposite (NiSe2/H) was prepared by a simple one-step hydrothermal route. The electrocatalytic performance of the as-synthesized nanocomposite and its components (pristine NiSe2and halloysite) toward OER in 1.0 KOH solution was examined. The NiSe2/H nanocomposite exhibited a significantly...
Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique
, Article Journal of Nanoparticle Research ; Volume 16, Issue 9 , September , 2014 ; ISSN: 13880764 ; Dolati, A ; Sharif University of Technology
2014
Abstract
Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO...
Effects of tin valence on microstructure, optical, and electrical properties of ITO thin films prepared by sol–gel method
, Article Journal of Sol-Gel Science and Technology ; Volume 75, Issue 3 , September , 2015 , Pages 582-592 ; 09280707 (ISSN) ; Dolati, A ; Sharif University of Technology
Kluwer Academic Publishers
2015
Abstract
Abstract: This study aimed to understand the microstructural, optical, and electrical properties of tin-doped indium oxide (ITO) prepared with tetravalent and divalent tin salts. The influence of tin valence on the electrical, optical, structural, and morphological properties of the films were characterized by the mean of four-point probe, thermogravimetric analysis, differential thermal analysis (DTA), UV–Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope. XRD results revealed formation of cubic bixbyite structure of In2 O3 with a small shift in major peak position toward lower angles with...
Deposition of Indium-tin-oxide on Glass By Sol-gel and Effect of Noble Dopants on the Optical and Electerical Properties of Indium-tin-oxide Thin Films
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
Thin film of Indium oxide doped with tin is used as a transparent electrode for different applications like screening panels, solar cells, touch panels and elechtrochromic tools. Trading thin films of ITO are precipitated using sputtering. However sol gel method can be simple and economic to make transparent electrodes. In this thesis first ITO sols is prepared using Indium nitrate and tin chloride with two or four capacities due to the production of transparent oxides on soda lime glass. Then the effect of tin chloride with two and four capacities is investigated on resistance and optic properties. Results show that tin chloride with four capacities in comparison with tin of two capacities...
Evaluation of the Endpoint Damage of Climate Change Due to Power Plant Emissions on the Human Health Using Life Cycle Analysis
, M.Sc. Thesis Sharif University of Technology ; Avami, Akram (Supervisor)
Abstract
Preserving and promoting the health of citizens in a society is one of the most important problems addressed in any country. The power sector discharges a huge volume of carbon dioxide which intensifies the climate change and consequent human health problems.The goal of this study is to evaluate the ultimate effect of climate change caused by power plant emissions on the human health using life cycle analysis approach for different provinces in Iran. An integrated model has been developed to evaluate the impact of climate change due to power plant emissions on the human health. This model includes the equations regarding the variations in carbon dioxide concentration in the atmosphere,...
Synthesis of CuCo2O4/BiVO4composites as promise and efficient catalysts for 4-nitrophenol reduction in water: Experimental and theoretical study
, Article Journal of Environmental Chemical Engineering ; Volume 9, Issue 4 , 2021 ; 22133437 (ISSN) ; Gholami, M. R ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study investigates the synthesis of CuCo2O4, BiVO4, and CuCo2O4/BiVO4 nanocomposite by the solvothermal method. The Physico-chemical properties of the samples were verified through Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Transmission Electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET). Evaluation of catalytic efficiency of the synthesized samples were done in promoting the 4-Nitrophenol reduction to 4-Aminophenol in the existence of high amount of sodium borohydride (NaBH4) as a reducing agent, and the progress of the catalytic reaction was monitored...
Application of Endurance Time Method in Performance-based Design
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
Endurance Time (ET) method is a dynamic analysis method in which the structure is subjected to an intensifying accelerogram and its response is recorded at different times.On the other hand a new method for designing earthquake resistant structures is Performance-Based Design (P-BD) method. P-BD is a methodology in which structural design criteria are expressed in terms of achieving a set of different performance objectives. In this research the application of ET method and target curve (which is defined based on ET method concepts) in the performance-based design has been studied.Correlating time in ET method and earthquake return period, the design,assessment and retrofitting of different...
A Historical Review on Darwin's Theories and Darwinism's Philosophical
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Hassan (Supervisor)
Abstract
This thesis reviews briefly historical backgrounds and contexts of Darwin's theory and summarizes and describes his arguments in the Origin, and studies philosophical issues around Darwinism. This thesis includes four chapters: chapter one reviews historical line from Greek thinkers to ninteenth century scientists; chapter two summarizes ideas and arguments in the Origin; chapter three discusses some philosophical issues briefly; and chapter four is devoted to some conclusion
A Deep Learning MIMO Communication System Based on Auto-encoder Design
, M.Sc. Thesis Sharif University of Technology ; Hossein Khalaj, Babak (Supervisor)
Abstract
Today, the use of deep learning algorithms in the design of communication systems has received much attention. One of these areas is the partial or total design of these systems using deep networks. The overall design of a communication system using deep networks allows for global optimization and can provide better performance in cases where classical methods have suboptimal performance without significantly increasing the computational load. In this research, a comprehensive architecture for designing communication systems based on Auto-encoder neural networks is presented. This architecture has the same functionality as classical systems, considering all parts of these systems including...
A case study in vapor phase synthesis of Mg-Al alloy nanoparticles by plasma arc evaporation technique
, Article Chemical Engineering Journal ; Volume 259 , 2015 , Pages 918-926 ; 13858947 (ISSN) ; Derakhshan, R ; Mirzaee, O ; Sharif University of Technology
Elsevier
2015
Abstract
Alloy nanoparticles in the Mg-Al system were prepared by plasma arc discharge method from the Mgx to Al (45%
Exact simulating of human arteries using lumped model and probing constriction in femoral and carotid arteries
, Article American Journal of Applied Sciences ; Volume 6, Issue 5 , 2009 , Pages 834-842 ; 15469239 (ISSN) ; Ghasemalizadeh, O ; Firoozabadi, B ; Sharif University of Technology
2009
Abstract
Problem statement: Modeling Human cardiovascular system was always an important issue from long past because by doing such modeling, investigation in cardiovascular system and its abnormities would be simpler. One of the most effective ways to do such modeling is using lumped method (Electrical analogy). Approach: Lumped method was used for simulating a complete model in this approach. A 36-vessel model was chosen to make equivalent circuit of lumped method from it. This complicated circuit includes equivalent segment for arteries, pulmonary, atrium, left and right ventricles. Furthermore, in this complex circuit some additional points were considered to improve this method. Some of the most...
MIL-88A derived CoFe-layered double hydroxides with optimized composition for the enhanced electrocatalytic oxygen evolution reaction
, Article New Journal of Chemistry ; Volume 47, Issue 11 , 2023 , Pages 5555-5563 ; 11440546 (ISSN) ; Hajilo, M ; Mirzaee Valadi, F ; Sharif University of Technology
Royal Society of Chemistry
2023
Abstract
The oxygen evolution reaction (OER) as the anodic half-reaction of water electrolysis has received growing attention due to its paramount role in the green and sustainable production of hydrogen fuel and metal-air batteries. Herein, we report the synthesis of five CoFe-layered double hydroxides (CoFe-LDHs) and their application toward the electrocatalytic OER in an alkaline medium. CoFe-LDHs were prepared via a novel hydrothermal route from the MIL-88A metal-organic framework (MOF). The Co-to-Fe ratios in the LDHs were systematically modified to tune the electrocatalytic activity in the OER. It was observed that the as-prepared Co0.39Fe0.61-LDH demonstrated a superior electrocatalytic...