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shayegh--zahra
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Intrinsic kinetic model for reaction of synthesis-gas to light olefins on CO/Mn catalyst
, Article 8th World Congress of Chemical Engineering: Incorporating the 59th Canadian Chemical Engineering Conference and the 24th Interamerican Congress of Chemical Engineering, 23 August 2009 through 27 August 2009, Montreal, QC ; 2009 , Pages - ; Manafi, H ; Ghotbi, C ; Bozorgmehri, R ; Sharif University of Technology
2009
Abstract
The kinetic experiments for the reaction of synthesis gas to light olefin over CO/Mn/TiO 2 catalyst were carried out in a micro-fixed-bed reactor. Rate expressions for reactions were selected based on the carbide mechanism. A differential reactor model considering both FTS and WGS kinetic models was used to describe the reaction systems. The simulation estimation of proposed kinetic model was conducted with a generic algorithm. This is an abstract of a paper presented at the 8th World Congress of Chemical Engineering (Montréal, Quebec, Canada 8/23-27/2009)
Effect of operation conditions on the catalytic performance of the Co/Mn/TiO2 catalyst for conversion of synthesis gas to light olefins
, Article Scientia Iranica ; Volume 17, Issue 2 C , November , 2010 , Pages 168-176 ; 10263098 (ISSN) ; Ghotbi, C ; Bozorgmehry Boozarjomehry, R ; Rashtchian, D ; Sharif University of Technology
2010
Abstract
The effect of operation variables, such as the H2/CO molar feed ratio, gas hourly space velocity (GHSV), temperature, and pressure, on the catalytic performance of the Co/Mn/TiO2 catalyst prepared at the Research Institute of the Petroleum Industry (RIPI) was investigated, and optimum reactor conditions were obtained to produce the maximum amount of light olefins. The catalyst was prepared by co-precipitation of Co and Mn phases in the presence of commercial TiO2 with maximum selectivity for ethylene and propylene production. It was found that the [H2]/[CO]=2/1, space velocity (GHSV) of 1800 h-1, 280°C temperature and 4 bar pressure were optimum operating conditions for the modified catalyst...
Photoactive TiO2–SiO2 Thin Films on 316L Stainless Steel for Self-Cleaning Application, Tribological Properties and Corrosion Protection
, Ph.D. Dissertation Sharif University of Technology ; Afshar, Abdollah (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
In this study, TiO2-SiO2 nanocomposite films with different amount of SiO2 were prepared by sol-gel process and were coated onto stainless steel 316L. The effect of addition of various amounts of SiO2 in the precursor solution on the structure, morphology, photocatalysis, photo-generated hydrophilicity, self-cleaning property and mechanical properties of TiO2 thin films and corrosion behavior of AISI 316L stainless steel substrate, was investigated. For this purpose, X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements, UV spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, depth-sensing indentation technique supporting...
Mesoporous silica nanoparticles (MCM-41) coated PEGylated chitosan as a pH-Responsive nanocarrier for triggered release of erythromycin [electronic resource]
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; 2014, Volume 63, Issue 13, Pages 692-697 ; Mazaheri Tehrani, Zahra ; Sharif University of Technology
Abstract
A pH-responsive drug delivery system based on core shell structure of mesoporous silica nanoparticle (MSN) and chitosan-PEG copolymer was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-resolution transmission microscope (HR-TEM) techniques. In order to improve compatibility MSN and drug, mesoporous nanosilica was modified by 3-aminopropyl triethoxysilane. The release of erythromycin (a macrolide antibiotic) as a model drug was investigated in two pHs, 7.4 and 5.5
Formation of Lanthanum hydroxide nanostructures: effect of NaOH and KOH solvents
, Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 2 , 2008 , Pages 169-176 ; 1728-144X (ISSN) ; Zanganeh, S ; Kajbafvala, A ; Shayegh, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
Materials and Energy Research Center
2008
Abstract
Lanthanum hydroxide (La(OH)3) nanostructures, including elliptical nanoparticles, octahedral rods and irregular nanoparticles were prepared chemically in NaOH and KOH solutions with 10 M concentration. The obtained powders were characterized with XRD, SEM, TEM and DTA. Crystallinities, morphologies and thermal behavior of the obtained nanostructure powders were investigated under the influence of above mentioned solvents. The effect of chemical's temperature was also determined in one of the solvents (i.e. NaOH). The formation of growth in nanostructure mechanism under the influence of alkali solutions (i.e., KOH and NaOH) have been discussed considerably in this paper
Nano-Zeolite Synthesis Adsorbents for Removal of Mercaptanes from the Butane and the Propane
, M.Sc. Thesis Sharif University of Technology ; Soltanieh, Mohammad (Supervisor) ; Shayegh, Flora (Supervisor) ; Soltanali, Saeed (Co-Advisor)
Abstract
In this study nano zeolite was hydrothermally synthesized in order to remove ethyl and methyl mercaptans from propane and butane stream. Fifteen experimental runs were conducted using D-Optimal method experimental design to synthesize NaY, NaX and NaA zeolites. The products were characterized by measuring the morphology, particle and crystal size, surface area, adsorption isotherm, pore size, and pore volume of the products by XRD, FE-SEM, TEM and BET analyses. The pore size for NaA type zeolites is about 4 Angstrom whereas the molecular size for ethyl mercaptan and methyl mercaptan is between 4 and 5 Angtrom, Therefore, NaA zeolite is inappropriate for removing ethyl and methyl mercaptans...
Design of a Mechanism and Construction of a Waste Collection Vessel Model for Port Waters
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehrani Fard, Majid (Supervisor)
Abstract
Today, environmental pollution has become a global issue, affecting both land and air, and oceans are no exception. Marine environments increasingly suffer from various forms of chemical and solid pollution, with floating solid waste among the most prevalent forms. Beaches and ports are the main sources of this waste, a significant portion of which is plastic. With the rapid growth in plastic production, concerns about floating waste have intensified globally. Consequently, numerous cultural initiatives and technological solutions have been proposed to combat this pollution. Waste collection systems are among the most effective approaches, and various types have been implemented. Since Iran...
Theoretical and Computational Investigation of Quantum Plasmonic Properties of Nanocluster Dimers
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Zahra (Supervisor)
Abstract
In today's era, metal nanoparticles play an important role in technologies emerging from different sciences, such as chemistry, physics, optics, material science, due to their unique characteristics. In the development of nanooptics science, it can be said that metal nanoparticles play an important role. The ability of conductive electrons collective oscillation causes surface charge density fluctuations in nanoparticles, this phenomenon is known as surface plasmons. Surface plasmons are surprisingly coupled with light and cause the significant increase in the intensity of optical fields induced in nanoparticles. Therefore, with the presence of localized surface plasmons or plasmon...
Theoretical Investigation of Ab-initio MD Approach to Increase the Efficiency and Accuracy of VCD Spectrum Calculation
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Zahra (Supervisor)
Abstract
Understanding of the Molecules is the main purpose of the chemistry. Ab-initio molecular dynamics (AIMD) as a branch of the computational chemistry, tries to give us a deep comprehension of the molecule, and its chemical, physical and optical activities. This comprehension, relies on the accuracy of quantum mechanics, in addition to the speed of the classical mechanics. The mixing of the quantum mechanics and the classical mechanics could simulate activities of the atoms in the time-domain, provided the mixing is done with precaution. This, in turn, helps us to forecast the response of a molecule in different situations, and also translating the macroscopic phenomena in a nanoscopic...
Investigation of Plasmonic Excitation in Carbonic Nanostructures Within Near-IR
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Zahra (Supervisor)
Abstract
To date, the plasmonic properties of many metallic and semi-conducting materials have been investigated and used in various industries. One of the plasmonic material categories that have always been considered is polycyclic aromatic hydrocarbon or PAH, whose plasmonic resonance energy depends on the charge state of the molecule. In this regard, it is easy to change the plasmonic resonance energy via changing the induced charge, which is a unique feature of the mentioned materials. In addition, plasmonic structures with excitations in the infrared region are able to enhance the vibration intensity of absorbed molecules by increasing the electric field around themselves. Therefore, they have...
Using Nonlinear Effects of Light for Optical Signal Processing
, M.Sc. Thesis Sharif University of Technology ; Kavehvash, Zahra (Supervisor)
Abstract
Ultrafast signal processing in time-domain with high resolution and reconfigura-bility is a challenging task. This paper, for the first time, introduces a time-varying metasurface consisting of graphene microribbon array for implementing time-lens in the terahertz domain. Given that the surface conductivity of graphene is proportional to the Fermi energy level in the THz regime, it is possible to change the phase property of the incident electromagnetic pulse by changing the Fermi level while the Fermi level itself is a function of voltage. Upon this fact, a quadratic temporal phase modulator, namely time-lens has been realized. This phase modulation is applied to the impinging signal in the...
Using Simulation-Optimization Approach for Fire Station Location and Vehicle Assignment Problem: a Case Study in Tehran, Iran
, M.Sc. Thesis Sharif University of Technology ; Amini, Zahra (Supervisor)
Abstract
In this research, the problem of locating fire stations and allocating equipment has been studied and a simulation-optimization approach has been presented to solve the problem. The mathematical models of this research were developed based on the idea of the randomness of the covered demand and the maximum expected coverage model. In these models, the issue of non-availability of equipment to cover accidents, the random nature of accidents, various fire incidents and the equipment needed to cover them are considered. Two mathematical models with deterministic and non-deterministic approach with different scenarios for demand are proposed. The non-deterministic model is developed with the aim...
Introducing An Integrated Framework For Solving The Fleet Planning Problem Using A Simulation-Optimization Approach
, M.Sc. Thesis Sharif University of Technology ; Amini, Zahra (Supervisor)
Abstract
One of the main concerns of industrial companies’ managers is providing an efficient logistics system. To achieve an efficient logistics system, the fleet planning problem is studied by many researchers in recent years. This problem consists of multiple sub-problems at three levels: operational, tactical, and strategic. These sub-problems are closely related to each other and need to be studied and addressed in an integrated manner. In this research, an attempt is made to provide an integrated framework to solve the vehicle routing problem (operational), outsourcing problem (tactical), and fleet composition problem (strategic). These problems have various uncertainties, including customer...
Super gas wet and gas wet rock surface: state-of- the art evaluation through contact angle analysis
, Article Petroleum ; 2021 ; 24056561 (ISSN) ; Dehghan Monfared, A ; Shayegh, F ; Barzegar, F ; Ghazanfari, M. H ; Sharif University of Technology
KeAi Communications Co
2021
Abstract
Recently, super gas wet and gas wet surfaces have been extensively attended in petroleum industry, as supported by the increasing number of publications in the last decade related to wettability alteration in gas condensate reservoirs. In many cases, contact angle measurement has been employed to assess the wettability alteration. Even though contact angle measurement seems to be a straightforward approach, there exist many misuses of this technique and consequently misinterpretation of the corresponding results. In this regard, a critical inspection of the most recent updated concepts and the intervening parameters in the contact angle based wettability evaluation of liquid-solid-gas...
Super gas wet and gas wet rock surface: State of the art evaluation through contact angle analysis
, Article Petroleum ; Volume 9, Issue 1 , 2023 , Pages 1-7 ; 24056561 (ISSN) ; Dehghan Monfared, A ; Shayegh, F ; Barzegar, F ; Ghazanfari, M. H ; Sharif University of Technology
KeAi Communications Co
2023
Abstract
Recently, super gas wet and gas wet surfaces have been extensively attended in petroleum industry, as supported by the increasing number of publications in the last decade related to wettability alteration in gas condensate reservoirs. In many cases, contact angle measurement has been employed to assess the wettability alteration. Even though contact angle measurement seems to be a straightforward approach, there exist many misuses of this technique and consequently misinterpretation of the corresponding results. In this regard, a critical inspection of the most recent updated concepts and the intervening parameters in the contact angle based wettability evaluation of liquid-solid-gas...
Optimizing Structure of Catalysts and Development of Kinetic Parameters for Synthesis Gas to Olefin Reaction
, Ph.D. Dissertation Sharif University of Technology ; Ghotbi, Siroos (Supervisor) ; Bozorg Mehri, Ramin (Supervisor) ; Zarrinpashne, Saeid (Supervisor)
Abstract
Synthesis gas to light olefin reactions especially propylene production is one of the important path for clean fuel production in gas conversion processes. The object of this study is to define true kinetic model of process first step (e.g. Synthesis gas to light Olefins). For that, kinetic model for Co/Mn/TiO2 catalyst, which has the best conversion and selectivity for propylene, has been developed. Kinetic reaction parameters were measured by kinetic modeling in (220-300)0C temperature , (1-5)bar pressure , H2/CO=(1:3) and (450-600)hr-1 space velocity .After studying with significant models ,the best fitting can obtained with "KPCO P 1/2H2/(1+aPco+bPH2 1/2)2"equation. Later to...
Analytical Modelling and Optimization of Disk Type, Slot Less Resolver
, M.Sc. Thesis Sharif University of Technology ; Nasiri Gheidari, Zahra (Supervisor)
Abstract
Resolvers, due to their robust structure, are widely used in automation systems. Among the types of resolvers, the accuracy of the Wound Rotor (WR) resolver in the occurrence of common mechanical errors is higher than other types of resolvers. therefore, in this thesis, an AFWRR is studied to improve the performance. Increasing the number of poles in WR resolvers is a good solution for increasing the accuracy of these electromagnetic position sensors. However, high-speed WR resolvers due to employing fractional slot windings suffer from rich sub-harmonics in the induced voltages. A common solution for suppressing the undesirable sub-harmonics is using multi-layer winding with appropriate...
A Survey on Searchable Symmetric Encryption Schemes
, M.Sc. Thesis Sharif University of Technology ; Khazaei, Shahram (Supervisor)
Abstract
Using “Searchable Encryption” enables us to encrypt the data, while preserving the possibility of running search queries. One of the most important applications of the mentioned is in Cloud Storage. As users do not trust the Cloud space, they are not inclined to store their data on the Could. The solution to this problem is of course, Cryptography. However, ordinary Cryptography methods, eliminate the data’s searchability. Hence, we need encryption schemes that code the data while retaining their searchability. So far, various schemes has been proposed that differ in their performance, security level, and usage. In this thesis, we aim to discuss and analyze these methods
Time Domain Optical Signal Processing Based on the Duality Between Dispersion and Diffraction
, M.Sc. Thesis Sharif University of Technology ; Kavehvash, Zahra (Supervisor)
Abstract
In the last decades, due to the growing demand of transferring information with high transmission rates, the complexity and development of telecommunication and optical systems is remarkable. Researchers around the world attempt to explore extraordinary potential of light to process information. In the mid-19th century, scientists discovered a mathematical symmetry between the spatial and temporal optics fields, which originated from the similarity of equations governing the paraxial diffraction of beams and the dispersion of narrow-band pulses known as space– time duality in scientific texts. This new approach provides more advanced and potent methods to temporal processing and...
Improving the Stability of an Urban Traffic Network with Limited Data by Using Percolation Theory and Dynamic Clustering
, M.Sc. Thesis Sharif University of Technology ; Amini, Zahra (Supervisor)
Abstract
One of the most vital aspects of understanding the traffic phenomenon is scrutinizing the traffic transition status, such as the transition from free flow to congestion. The Percolation Theory is a renowned theory focusing on analyzing various network types to detect the critical zones, which are the zones including links that are important to control to improve stability. By calculating the quality indices of network links, the Percolation Theory can simulate the traffic percolation propagation in the network and determine possible critical zones for further analysis. Most studies in this field assume access to data of several traffic parameters for the entire transportation network, such...