Synthesis of Pure Aluminum Nanoparticles by Electromagnetic Levitation Melting Gas Condensation

, M.Sc. Thesis Sharif University of Technology Sabooni Tabari, Ra’na (Author) ; Halali, Mohammad (Supervisor)

Abstract

In current project, high purity nanoparticles were synthesized by use of Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. In this case high purity aluminum samples were melted by this method to a temperature of 1683 0C in a silica tube. High purity argon and helium gases were employed as carrier gases and cooling agents. To study particle size, morphology, and purity of obtained nanoparticles, Field Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), Dynamics Light Scattering (DLS), and ADS analysis were employed. The FE-SEM and DLS tests confirmed narrow size distribute of spherical shape pure aluminum nanoparticles under both inert gases. The...

Comparative evaluation of advanced gas turbine cycles with modified blade cooling models [electronic resource]

, Article Proceedings of the ASME Turbo Expo ; Volume 4, Pages 537-546 , 2006 Tabari, A ; Sharif University of Technology

2006

Abstract

Advanced gas turbine cycles use advanced blade cooling technologies to reach high turbine inlet temperature. Accurate modeling and optimization of these cycles depend on blade cooling model. In this study, different models have been used to simulate gas turbine performance. The first model is the continuous model and the second is stage-by-stage model with alternative methods for calculating coolant, stagnation pressure loss and SPR. Variation of specific heat and enthalpy with temperature are included in both models. The composition of gas stream in turbine is changed step by step due to air cooling. These models are validated by two case study gas turbine results, which show good agreement...

Modeling Persian Language in the Framework of Complex Networks

, M.Sc. Thesis Sharif University of Technology Sabooni Aghdam, Amir Mahdi (Author) ; Bahrani, Mohammad (Supervisor)

Abstract

The interest in analyzing human language with complex networks is on the rise in recent years and a considerable body of research in this area has already been accumulated.However unfortunately, the use of applications of complex networks in Persian Linguistics research is missing. With the goal of introducing complex networks and their applications in this field, two of these applications have been studied in this research. First, we tried to build an inclusive network model, considering two levels of Syntax and Word Cooccurrence, for the Persian Language and provide Linguistics interpretations for them. In addition, by comparing co-occurrence networks of different languages, garnered from...

Using Social Network Patterns to Improve Evolutionary Algorithms

, M.Sc. Thesis Sharif University of Technology Molaie Tabari, Behin (Author) ; Habibi, Jafar (Supervisor)

Abstract

Evolutionary algorithm is an important algorithm in software field. Today evolutionary algorithms are used in many applications such as Artificial Art, Automated Design, Bio-informatics, Communications, etc. Many articles has been published in this field. The Evaluation of this algorithms have two approaches, the quality of result and the runtime of the algorithm. In this thesis we proposed a new use of Social Networks in Genetic Algorithm, and we designed a parallel model of it on CUDA GPUs. The main idea was that we seen a good content spread in the social networks very easy and fast. We used this idea to improve genetic algorithm by creating a social network between people of a...

Efficient dye-sensitized solar cells based on carbon-doped TiO2 hollow spheres and nanoparticles

, Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 11 , 2015 , Pages 8863-8876 ; 09574522 (ISSN) Tabari Saadi, Y ; Mohammadi, M. R ; Sharif University of Technology

Springer New York LLC 2015

Abstract

Different structures of TiO2 photoelectrodes are fabricated with various arrangement modes of the layers. TiO2 nanoparticles, synthesized by stabilizing agent free non-hydrolytic sol–gel method, are employed as the under layer, whereas carbon-doped TiO2 hollow spheres, prepared by hydrothermally grown carbon template, are used as the scattering layer of solar cells. The nanoparticles (22 nm) have anatase structure, while 300–700 nm hollow spheres show mixtures of anatase and rutile phases. X-ray photoelectron spectroscopy confirms that carbon is doped into TiO2 hollow spheres, resulting in a decrease in band gap energy in the range 2.96–3.13 eV compared with 3.04 eV band gap energy for the...

Comparative evaluation of advanced gas turbine cycles with modified blade cooling models

, Article 2006 ASME 51st Turbo Expo, Barcelona, 6 May 2006 through 11 May 2006 ; Volume 4 , 2006 , Pages 537-546 ; 0791842398 (ISBN); 9780791842393 (ISBN) Tabari, A ; Khaledi, H ; Hajilouy Benisi, A ; Sharif University of Technology

2006

Abstract

Advanced gas turbine cycles use advanced blade cooling technologies to reach high turbine inlet temperature. Accurate modeling and optimization of these cycles depend on blade cooling model. In this study, different models have been used to simulate gas turbine performance. The first model is the continuous model and the second is stage-by-stage model with alternative methods for calculating coolant, stagnation pressure loss and SPR. Variation of specific heat and enthalpy with temperature are included in both models. The composition of gas stream in turbine is changed step by step due to air cooling. These models are validated by two case study gas turbine results, which show good agreement...

Retrofit and Design of Concrete Beams by Using Active Tendons

, M.Sc. Thesis Sharif University of Technology Mohsen Zadeh Tabari, Golnaz (Author) ; Khaloo, Alireza (Supervisor)

Abstract

Structural elements are exposed to different types of loading which may cause excessive deformations during their life cycle. These deflections may cause damage to the structure .Therefore; reduction of dynamic response of structures can be achieved by exploiting active control system.
In this research, the dynamic behavior of prestressed Eulthemer Bernollli concrete beam under moving Load, support excitation and multi support excitation, controlled by active tendon is studied.The control algorithm employed in this thesis is closed loop linear classical optimal control with displacement-velocity feedback. R and Q matrices are chosen in order to balance the source energy consumption and...

Synthesis of Titania Hollow Spheres in Dye Sensitized Solar Cell Application

, M.Sc. Thesis Sharif University of Technology Tabari Saadi, Yasaman (Author) ; Mohammadi, Mohammad Reza (Supervisor)

Abstract

In the current research, Anatase-Rutile Titania hollow spheres were synthesized using hydrothermally prepared carbon spheres as template. Different calcination temperatures were used to remove carbon template and crysalized Titania. The characterizations for the physicochemical properties of prepared samples were carried out by XRD, FESEM, XPS, DRS, UV-Vis and FTIR.It is found that doping of carbon in the crystal structure of Titania hollow sphere, cause red shift in band gap wavelenght and the absorption wavelength edge was expanded to the visible light region and the additional diffusive electronic states were observed on the valence band spectra of samples.The photoelectric conversion...

Promoting the optimal maintenance schedule of generating facilities in open systems

, Article International Conference on Power System Technology, PowerCon 2002, 13 October 2002 through 17 October 2002 ; Volume 1 , 2002 , Pages 641-645 ; 0780374592 (ISBN); 9780780374591 (ISBN) Tabari, N. M ; Ranjbar, A. M ; Sadati, N ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2002

Abstract

This paper presents a dynamic programming methodology for finding the optimum preventive maintenance schedule of generating units of a GENCO in open power systems. The objective function for the GENCO is to sell electricity as much as possible, according to the market price forecast. Various constraints such as generation capacity, duration of maintenance and maintenance crew are taken into account. In a case study, introducing a GENCO with six generating units, and implementing dynamic programming, we obtain the optimal maintenance schedule over the planning period. © 2002 IEEE

Spatio-temporal variation of hydro-climatic variables and extreme indices over Iran based on reanalysis data

, Article Stochastic Environmental Research and Risk Assessment ; Volume 36, Issue 11 , 2022 , Pages 3725-3752 ; 14363240 (ISSN) Malaekeh, S. M ; Safaie, A ; Shiva, L ; Tabari, H ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2022

Abstract

A comprehensive investigation of historical hydro-climatic changes at a county level is an essential prerequisite of developing any adaptation or mitigation strategies to deal with the destructive impacts of climate change. In this study, spatial distributions and trends in thirty-seven hydro-climatic mean and extreme indices across Iran were analyzed based on the state-of-the-art reanalysis datasets (ERA5-Land and AgERA5) at the county level from 1986 to 2015 using several nonparametric approaches such as multiple modified Mann–Kendall statistical tests and Sen’s Slope estimator. Their interannual oscillations were also examined using continuous wavelet transform to portray a complete...

Production of waste bio-fiber cement-based composites reinforced with nano-SiO 2 particles as a substitute for asbestos cement composites

, Article Construction and Building Materials ; Volume 31 , 2012 , Pages 105-111 ; 09500618 (ISSN) Hosseinpourpia, R ; Varshoee, A ; Soltani, M ; Hosseini, P ; Ziaei Tabari, H ; Sharif University of Technology

2012

Abstract

The environmental impact of asbestos fibers on human health and their consequent safety-related problems indicate that there is a significant need to replace this material in all asbestos-containing products. Many different types of fibers have been introduced to replace asbestos fibers. In this study, the performance of silica nano-particles combined with waste paper pulp fibers (sulfite fibers) has been investigated. Different mechanical (compressive and flexural strengths and bending performance), durability (water absorption), physical (bulk density and flowability), and microstructural (scanning electron microscopy) tests were conducted to examine the properties of manufactured green...

Experimental analysis and characterization of high-purity aluminum nanoparticles (Al-Nps) by electromagnetic levitation gas condensation (ELGC)

, Article Nanomaterials ; Volume 10, Issue 10 , 2020 , Pages 1-15 Sabouni Tabari, R ; Halali, M ; Javadi, A. A ; Khanjanpour, M. H ; Sharif University of Technology

MDPI AG 2020

Abstract

The production of high-purity aluminum nanoparticles (Al-NPs) is challenging due to the highly reactive nature of Al metals. Electromagnetic levitation gas condensation (ELGC) is a promising method to produce high-purity metallic particles as it avoids the interaction between molten metal and refractory-lined, which guarantees the removal of impurities such as oxygen (O). In this research, high-purity Al-NPs were successfully fabricated via ELGC process and fully characterized. The effects of power input and gas flow rate on particle size and distribution were analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and dynamic light...