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Modelling of fischer-tropsch synthesis in a fluidized bed reactor

, Article Advanced Materials Research ; Volume 586 , 2012 , Pages 274-281 ; 10226680 (ISSN) ; 9783037855232 (ISBN) Kazemeini, M ; Maleki, R ; Fattahi, M

2012

Abstract

The FT reaction involves the conversion of syngas which is derived from natural gas or coal to different kinds of products according to the operating conditions and the type of the catalyst. In other words, it is a practical way to convert solid fuel (coal) and natural gas to various hydrocarbons (C1-C60) and oxygenates such as alkanes, alkenes etc. The main products of the reaction are naphtha and gasoline. This paper deals with developing a proper product distribution model for FT process using the appropriate kinetic model, optimizing the respective rate constants while applying them in product distribution equations. The results revealed only 8.09% deviations from the olefin experimental...

A fuzzy random minimum cost network flow programming problem [electronic resource]

, Article Journal of Industrial and Systems Engineering (JISE)-Iranian Institute of Industrial Engineering ; Article 3, Volume 6, Issue 1, Spring 2012, Page 34-47 Nematian, J. (Javad) ; Eshghi, Kourosh ; Sharif University of Technology

Abstract

In this paper, a fuzzy random minimum cost flow problem is presented. In this problem, cost parameters and decision variables are fuzzy random variables and fuzzy numbers respectively. The object of the problem is to find optimal flows of a capacitated network. Then, two algorithms are developed to solve the problem based on Er-expected value of fuzzy random variables and chance-constrained programming. Furthermore, the results of two algorithms will be compared. An illustrative example is also provided to clarify the concept

Special classes of mathematical programming models with fuzzy random variables [electronic resource]

, Article Journal of Intelligent and Fuzzy Systems, Published In: IOS Press ; Volume 19, Number 2, 2008 Eshghi, K. (Kourosh) ; Nematian, Javad ; Sharif University of Technology

Abstract

In this paper, we will discuss two special classes of mathematical programming models with fuzzy random variables. In the first model, a linear programming problem with fuzzy decision variables and fuzzy random coefficients is introduced. Then an algorithm is developed to solve the model based on fuzzy optimization method and fuzzy ranking method. In the second model, a fuzzy random quadratic spanning tree problem is presented. Then the proposed problem is formulated and solved by using the scalar expected value of fuzzy random variables. Furthermore, illustrative numerical examples are also given to clarify the methods discussed in this paper

A special class of fuzzy integer programming model with all different constraints [electronic resource]

, Article Scientia Iranica ; Vol. 16, No. 1, pp. 1-10, 2009 Eshghi, K. (Kourosh) ; Nematian, Javad ; Sharif University Of Technology

Abstract

In this paper, a fuzzy approach is applied to special classes of integer programming problems with all diierent constraints. In the rst model, a fuzzy integer programming model is developed to represent the all-diierent constraints in mathematical programming. In order to solve the proposed model, a new branching scheme for the Branch and Bound algorithm is also presented. In the second model, a special class of large-scale multi-objective fuzzy integer programming problems with all-diierent constraints is introduced. A solution method for the proposed model is also developed by using the decomposition technique, weighting method and Branch and Bound algorithm. An illustrative numerical...

Fuzzy random minimum cost network problem [electronic resource]

, Article Journal of Industrial and Systems Engineering ; Vol. 6, No. 1, pp 34-47, 2012 Nematian, J. (Javad) ; Eshghi, Kourosh ; Sharif University of Technology

Abstract

In this paper, a fuzzy random minimum cost flow problem is presented. In this problem, cost parameters and decision variables are fuzzy random variables and fuzzy numbers respectively. The object of the problem is to find optimal flows of a capacitated network. Then, two algorithms are developed to solve the problem based on Er-expected value of fuzzy random variables and chance-constrained programming. Furthermore, the results of two algorithms will be compared. An illustrative example is also provided to clarify the concept

Novel manufacturing process of nanoparticle/Al composite filler metals of tungsten inert gas welding by accumulative roll bonding

, Article Materials Science and Engineering A ; Volume 648 , 2015 , Pages 47-50 ; 09215093 (ISSN) Fattahi, M ; Noei Aghaei, V ; Dabiri, A. R ; Amirkhanlou, S ; Akhavan, S ; Fattahi, Y ; Sharif University of Technology

Elsevier Ltd 2015

Abstract

In the present work, accumulative roll bonding (ARB) was used as an effective method for manufacturing nanoparticle/Al composite filler metals of tungsten inert gas (TIG) welding. After welding, the distribution of ceramic nanoparticles and mechanical properties of welds were investigated. By applying ARB, ceramic nanoparticles were uniformly dispersed in the composite filler metals. Consequently, the welds produced by these filler metals had a uniform dispersion of ceramic nanoparticles in their compositions. The test results showed that the yield strength of welds was greatly increased when using the nanoparticle/Al composite filler metals. The improvement in the yield strength was...

Exploring of Influence of Boron on Acidity of Organic Functional Groups by DFT Calculation

, M.Sc. Thesis Sharif University of Technology Mehrpajouh, Sima (Author) ; Fattahi, Alireza (Supervisor)

Abstract

Acidity values of some compound (e.g., alkanes, alcohols, carboxylic acids and amines) with or without boron substitute have been studied theoretically to evaluate the influence of boron on acidity of organic functional groups. We have derived the unoccupied reactive orbital that show the maximum localization on the boron pπ atomic orbital overlapping with the lone-pair orbital of an electron donor. Localization of unoccupied reactive orbital on the boron pπ atomic and the polarizability of the boron center are two factors which affect acidity values of functional groups. Conformational searching was performed using MM (Molecular Mechanics). The most important conformations were optimized at...

, M.Sc. Thesis Sharif University of Technology Eiravani, Hossaen (Author) ; Fattahi, Alireza (Supervisor)

Abstract

It is believed that intramolecular hydrogen bonding and also conjugation can affect the acidity power of organic molecules. But simultaneous effects of intramolecular hydrogen bonding and conjugation have not investigated systematically yet. In this project, we choose Ascorbic acid as a basic structure. Then we have changed its structure conveniently, and have explored the roles of hydrogen bonding and conjugation on the acidity of this molecule by using B3LYP functional with the 6-311++G(d,p) basis set. After that we similarly investigate these effects on the acidity of three different systems, including enols, enamines and alcohols. In this project we probe the effect of different hydrogen...

AdS3/CFT2 In The Presence of N=1 Supergravity

, M.Sc. Thesis Sharif University of Technology Fattahi, Mohammad (Author) ; Rouhani, Shahin (Supervisor)

Abstract

Brown and Henneaux showed that asymptotic symmetries of asymptotically form a conformal group in two dimensions [1]. Also they could derive classical central charge of theory. Fourteen years later, Maldacena, conjectured that this Holographic correspondence could be true for a specific theory a simplified chromodynamics in the boundary of ), this holographic theory attracted physicist communitee's attention. Many physicists tried to make this conjecture more precise. It is worth to say that, no example of holographic correspondence has been completely proven, till now, Because of the difficulty of the calculation. However these days we consider Madacena conjectrure in any arbitrary...

Direct Torque Control of Brushless Doubly-Fed Induction Machines Using Fuzzy Logic

, M.Sc. Thesis Sharif University of Technology Fattahi, Javad (Author) ; Khayyat, Amir (Supervisor)

Abstract

This thesis contributes two separate predictive direct torque control methods; based on hysteresis and fuzzy logic for Brushless Doubly Fed Induction Machine (BDFM). Initially Chapter 1, focuses on BDFM history and concept of this machine and after that a short review about the development of BDFM and the Field Oriented Control will be studied. Chapter 2 introduces the d-q-0 state transformation matrix, dynamic equation of BDFM and represents its steady-state equivalent. Furthermore, in this chapter the bond graph model of BDFM is studied and via distinguishing all energy ports the bond graph model of this motor is introduced and validated, finally the result of this model is compared with...

A Meta Heuristic Approach for Design of a Network System in Mass Customization

, M.Sc. Thesis Sharif University of Technology Puresmaili, Ehsan (Author) ; Fattahi, Omid (Supervisor)

Abstract

This study discusses about mass customization and optimization of supply network in which both goal considering to set the flow of raw material and final product to satisfy the customer demand. The mass customization is more important concept in this study, so that this goal is placed to the first objective. In this research, the model which contained both goal is presented. The model focus on mass customization and try to satisfy various products demand, which constitute 3 kind of speed demands. Each product can satisfy in 3 way: fast, normal, slow.In the first model the new approach present in which the speed affects all of supplying, manufacturing and distributing system. The system try...

Identifying the risks of Iranian Knowledge BasedFirms Using Fault Tree Analysis (FTA)

, M.Sc. Thesis Sharif University of Technology Sarhadi, Maryam (Author) ; Fattahi, Omid (Supervisor)

Abstract

Knowledge Based Firms are considered to be important for the economic development of a country in regards to both employment growth and innovative activity. The latter is believed to contribute significantly to the increase in productivity and therefore the competitiveness of Iran’s economy. This study contributes to the above literature by investigating the factors that are believed to treat the growth of such firms in Iran. The purpose of this study is to identify functional risks of vital signs monitors via Fault Tree Analysis (FTA) method to use as a guide for manufacturers to identify and control hazards. Therefore, 30 knowledge based firms were selected as sample. Then, based on a...

Conversion of a weak organic acid to a super acid in the gas phase

, Article Journal of Physical Organic Chemistry ; Volume 21, Issue 2 , 2008 , Pages 112-118 ; 08943230 (ISSN) Fattahi, A ; Tavasoli, E ; Sharif University of Technology

2008

Abstract

The effects of selected metal ions on the gas-phase acidity of weak organic acids have been explored using the DFT and Moller-Plesset Perturbation Theory (MP2) calculations. The three organic acids selected for this study were acetic acid (aliphatic), benzoic acid (aromatic), and glycine (amino acid). The acidities of these compounds are compared with the acidity of their Li +-, Na+-, and K+ -complexed species. The results indicate that upon complexation with Li+, Na+, and K+ at 298K, the gas-phase acidity of acetic acid, for example, varies from 345.3 to 218.8, 230.2, and 240.1 kcal/mol, respectively (i.e., its dissociation becomes much less endothermic). These values indicate that a weak...

Design of Drug Structures in Order to Inhibit Met, A Member of the Tyrosine Phosphatase Protein Family to Replace Existing Drugs

, M.Sc. Thesis Sharif University of Technology Zeinal, Mostafa (Author) ; Fattahi, Alireza (Supervisor)

Abstract

This project aims to design a novel structure that can inhibit the activitvation of the c-Met enzyme using amino acids and sugars building blocks. The c-Met enzyme is a receptor tyrosine kinase that plays a significant role in several biological activities such as cell proliferation, survival, and invasion. Abnormal activity of the enzyme is linked to the progression of various types of cancer, including breast, lung, liver, and stomach cancer. The proposed sugar amino acid conjugate structures is expected to increase stability amino acids and dipeptides in the physiological environment, improve membrane permeability via active transport mechanism, and reduce toxicity and side effects by...

Investigating the Effect of the Proposed CSF-1R Protein Inhibitor,with a Structure Containing Natural Biomolecules and based on the Approved Drug Vimseltinib

, M.Sc. Thesis Sharif University of Technology Ebtehaj, Pouria (Author) ; Fattahi, Alireza (Supervisor)

Abstract

Vimseltinib, a small molecule inhibitor, represents a promising avenue for combating cancers linked to macrophage-associated processes through its targeted action on the CSF1R tyrosine kinase receptor. CSF1R, a pivotal member of the tyrosine kinase receptor family, plays a crucial role in macrophage differentiation and function. This protein's significance is underscored in conditions such as tenosynovial giant cell tumors (TGCTs) and the presence of tumor-associated macrophages, wherein overproduction of CSF1 by neoplastic cells recruits CSF1R-dependent immune cells, fostering tumor expansion. The intricate interplay extends to tumor-associated macrophages, particularly the M2 subtype,...

DFT Study on Mechanism and Kinetic of Thiotepa and Tepa Interaction with its DNA Receptor

, M.Sc. Thesis Sharif University of Technology Torabifard, Hedieh (Author) ; Fattahi, Alireza (Supervisor)

Abstract

N, N′, N″-triethylenethiophosphoramide (Thiotepa) and its oxo analogue (Tepa) as the major metabolite are trifunctional alkylating agents with a broad spectrum of antitumor activity. In vivo and vitro studies show alkylation of DNA by Thiotepa and Tepa can follow two pathways, but it remains unclear which pathway represents the precise mechanism of action. In pathway 1, these agents are capable of forming cross-links with DNA molecules which can be carried out via two different mechanisms. In the first mechanism, the ring opening reaction is initiated by protonating the aziridine, which then becomes the primary target of nucleophilic attack by the N7-Guanine of DNA. The second one is the...

Influence of Intramolecular Hydrogen Bonding on Ability of Leaving Group in SN2 Reactions

, M.Sc. Thesis Sharif University of Technology Ahmadi, Aliakbar (Author) ; Fattahi, Alireza (Supervisor)

Abstract

Many of the significant reactions in chemistry and biology are related to bimolecular nucleophilic substitution (SN2) reactions which have been studied first by Hughes and Ingold in the 1930s. Afterward, many organic chemists have continued this work. Up to now, numerous experimental kinetic and theoretical researches have studied the mechanism of these reactions. Since most SN2 reactions occur in solution, a large number of these studies have been devoted to the solvent effects. One of these effects that has been examined extremely is H-bonding via protic solvents that lowers the energy of an anionic nucleophile relative to the transition state, in which the charge is more diffuse, and...

Product Portfolio Management Using Life Cycle Considerations

, M.Sc. Thesis Sharif University of Technology Ebrahimian, Mahsa (Author) ; Fattahi, Omid (Supervisor)

Abstract

Today’s organizations always encounter limitations on the way of achieving their goals. Budget constraint, inventory constraints, capital constraints are issues which complicates management decision making.
Global market has enabled manufacturers compete globally. Even position their factories in other countries and use of competitive advantages and other markets demand. This is why decision making in production and manufacturing domain has been complicated. Decision making in production and manufacturing should become faster and more precise in order to keep market competitiveness. Organization should make long term or strategic decisions and short term decisions about keeping the...

Study of Change of Thermochemical Properties of DNA bases in the Presence of Neutral, Anionic, and Radical Species

, M.Sc. Thesis Sharif University of Technology Mottaghizadeh, Ayda (Author) ; Fattahi, Alireza (Supervisor)

Abstract

Since we are exposed to many air pollutants such as different gases daily, this project has attempted to investigate how these gases affect nucleobases, which are the main constituent of the DNA chain. The gases used in this study are sulfur dioxide (SO2), carbon monoxide (CO) and nitric oxide (NO). Each of these gases was studied separately along with the most stable nucleobase in the neutral, anionic and cationic states. The AT and GC base pairs were also exposed to each of these gases and changes (for exampl, the acidity, proton affinity) created in the AT and GC base pairs were examined.The most important properties studied during this project include gas-nucleobase interactions, proton...

Production of Uranium Dioxide Nano Powder With Hydrothermal Method in Supercritical Water Reactor

, M.Sc. Thesis Sharif University of Technology Golzary, Abooali (Author) ; Outokesh, Mohammad (Supervisor) ; Ahmadi, Javad (Supervisor) ; Karimi Sabet, Javad (Co-Advisor)

Abstract

Hydrothermal supercritical method is one of the most suitable methods for metal oxide nano powder, ceramics and mineral catalyst synthesis. Metal oxides nanopowder in its pure or mixed form has wide potential application as chemical industrial catalyst, hot Superconductors, magnetic material, gas sensors and car catalyst convertors. One of the most important metal oxides aspects of application is uranium oxide as nuclear reactor fuel is used. In addition, UO2 is selective catalyst for converting methane to methanol process and Decomposition of organic Chlorine material. In Supercritical hydrothermal method done in high pressure reactor with critical to fluid, is new method for the...