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ayati--behrouz
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Probabilistic Reasoning in Collaborative Filtering
, M.Sc. Thesis Sharif University of Technology ; Izadi, Mohammad (Supervisor)
Abstract
In this thesis the usage of probabilistic reasoning in collaborative filtering is investigated. The problem of predicting users' rating is formulated as a Bayesian decision problem and a generative probabilistic model is used in order to find the optimal decision. Two different probabilistic models are considered: user based model and rating based model. In user based model prediction of ratings is based on structural learning of Bayesian networks. In rating based model, we assume a predefined Bayesian network represents the joint distribution over model variables and rating prediction is carried out using McMc inference method. MovieLens dataset is chosen to evaluate and compare the results...
Experimental Investigation of the Effect of Nozzle Exit Flow on the Aerodynamic Behavior at Transonic Speed
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor)
Abstract
The aim of this investigation is the experimental study of nozzle exhaust jet flow effects on aerodynamic behavior of an air vehicle at transonic speeds. For this sake, a secondary jet injection is used by the ejector into test model. The ejector total pressure for jet injection varies between 0 (jet off) to 4 bar for simulating nozzle exhaust jet flow and supplying intake’s required mass flow rate. All tests were conducted at QRC Trisonic wind tunnel and at Mach number of 0.5 to 0.85 and angles of -4 to 6 deg. The aerodynamic force and pressure results were recorded in order to analyze the exhaust jet flow. This study revealed that the aerial vehicle drag becomes bigger than its free flight...
Design and Synthesis of Metal Nanocatalysts Immobilized on Magnetic Nanoparticles and their Application in Organic Reactions such as Coupling and Synthesis of Triazoles
, Ph.D. Dissertation Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
In this thesis, heterogenous catalysts based on magnetic nanoparticles coated with organosilanes and poly(ionic liquids) were synthesized. These catalysts were synthesized by hydrolysis of tetraethyl organosilanes and other organosilicons such as 3-aminopropyl triethoxy silane and polymerization of some monomers in the presence of ionic cross-link agents. The synthesized matrixes were used to stabilize precious metals such as Pd and Au. The magnetic properties of the catalysts aid to easy separation from the reaction medium by an external magnetic field. High thermal stability low toxicity and high-level loading of metals are some beneficiaries of the magnetic catalysts. At the end,...
A reconfigurable fault-tolerant routing algorithm to optimize the network-on-chip performance and latency in presence of intermittent and permanent faults
, Article Proceedings - IEEE International Conference on Computer Design: VLSI in Computers and Processors ; 2011 , Pages 433-434 ; 10636404 (ISSN) ; 9781457719523 (ISBN) ; Modarressi, M ; Sarbazi Azad, H ; Sharif University of Technology
2011
Abstract
As the semiconductor industry advances to the deep sub-micron and nano technology points, the on-chip components are more prone to the defects during manufacturing and faults during system operation. Consequently, fault tolerant techniques are essential to improve the yield of modern complex chips. We propose a fault-tolerant routing algorithm that keeps the negative effect of faulty components on the NoC power and performance as low as possible. Targeting intermittent faults, we achieve fault tolerance by employing a simple and fast mechanism composed of two processes: NoC monitoring and route adaption. Experimental results show the effectiveness of the proposed technique, in that it offers...
Dynamic Modeling and Congestion Control in Computer Networks
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor) ; Ebrahim, Behrouz (Co-Advisor)
Abstract
Active queue management (AQM) is a key factor in congestion control and should provide appropriate feedback for flow control in traffic sources to overcome the congestion problem. Beside providing congestion control, achieving predictable queuing delay, maximizing link utilization, simplicity and robustness are also the main objectives of an AQM controller. We propose in this thesis an improved queue dynamic model while incorporating the packet drop probability as well. The proposed model is evaluated using ns2 platform. By applying the improved model, a new compensated proportionalintegral- derivative (PID) AQM controller is developed for TCP network. The time-varying nature of the network...
Palladium immobilized onto functionalized magnetic nanoparticles as robust catalysts for amination and room-temperature ullmann homocoupling of aryl halides: a walk around the C−F bond activation
, Article Asian Journal of Organic Chemistry ; Volume 7, Issue 4 , 2018 , Pages 802-809 ; 21935807 (ISSN) ; Pourkaveh, R ; Karimi, A ; Ayati, E ; Sharif University of Technology
Wiley-VCH Verlag
2018
Abstract
The first example of a heterogeneous catalytically active system for Buchwald–Hartwig and Ullmann homocoupling of unactivated aryl halides (fluorobenzene) is presented. The novel magnetic heterogeneous palladium catalyst was synthesized by immobilization of palladium ions onto an aminopyridine-functionalized Fe3O4. The catalyst was fully characterized by FTIR spectroscopy, temperature-programmed reduction, thermogravimetric analysis, CHN elemental analysis, transmission electron microscopy, field-emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and atomic absorption spectroscopy. By using this catalyst system, various types of primary and...
Recovery of Uranium(VI) from UCF Waste by Selective Transportacross Aliquid Membrane
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Fasihi, Javad (Supervisor)
Abstract
Due to environmental and economical impacts, recovery of the uranium from nuclear wastes is of continuing interest.This work reports the separation of uranyl ionusing transport technique through chloroform liquid membrane containing a mixture of DBDA15C4 and oleic acidas cooperative carrier.The pH of the feed phase (10-4 M of UO22+) was adjusted with nitric acid and acetic acid/NaOH for pHrange of 2-6.The receiving phase was hydrochloric acid 1M.The organic phase was chloroform which includesthe carrier DBDA15C4 (0.0001 M) and also the oleic acid (0.015M).The results showed that the transport increased with increasing pH and reached to maximumat pH of 5.Maximum cooperative effect of oleic...
Overcoming drug resistance by co-targeting
, Article Proceedings - 2010 IEEE International Conference on Bioinformatics and Biomedicine, BIBM 2010, 18 December 2010 through 21 December 2010 ; December , 2010 , Pages 198-202 ; 9781424483075 (ISBN) ; Taheri, G ; Arab, S ; Wong, L ; Eslahchi, C ; Sharif University of Technology
2010
Abstract
Removal or suppression of key proteins in an essential pathway of a pathogen is expected to disrupt the pathway and prohibit the pathogen from performing a vital function. Thus disconnecting multiple essential pathways should disrupt the survival of a pathogen even when it has multiple pathways to drug resistance. We consider a scenario where the drug-resistance pathways are unknown. To disrupt these pathways, we consider a cut set S of G, where G is a connected simple graph representing the protein interaction network of the pathogen, so that G-S splits to two partitions such that the endpoints of each pathway are in different partitions. If the difference between the sizes of the two...
A novel highly dispersive magnetic nanocatalyst in water : Glucose as an efficient and green ligand for the immobilization of copper(II) for the cycloaddition of alkynes to azides
, Article RSC Advances ; Volume 6, Issue 83 , 2016 , Pages 80234-80243 ; 20462069 (ISSN) ; Saberi, V ; Kalhor, S ; Ayati, S. E ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
A new heterogeneous and highly dispersive nanocatalyst in water was prepared by the immobilization of Cu2+ onto glucose on Fe3O4. The catalyst was fully characterized by FT-IR, TGA, CHN, SEM, EDX, and atomic absorption spectroscopy. The synthesized catalyst was used in the synthesis of different derivatives of 1,2,3-triazole via a one-pot three-component reaction of alkynes, alkyl halides, and sodium azide. To the best of our knowledge, this novel catalyst adheres to the principles of green chemistry. The nanocatalyst could be recycled and reused in several runs without significant loss of activity
Copper loaded cross-linked poly(ionic liquid): Robust heterogeneous catalyst in ppm amount
, Article RSC Advances ; Volume 5, Issue 38 , 2015 , Pages 29609-29617 ; 20462069 (ISSN) ; Hosseini, S. H ; Matloubi Moghaddam, F ; Ayati, S. E ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
A novel heterogeneous copper catalyst was synthesized in which poly(1-vinyl imidazole-co-ionic liquid) was used as a solid heterogeneous support. The catalyst was readily synthesized in a large scale amount. The catalyst has a high loading level of copper ions and can be used in low weight percentages. The resulting catalyst was highly active in the preparation of triazoles by the Huisgen 1,3-dipolar cycloaddition method. In some cases the catalytic turnover number and frequency reached 70 002 and 3889 h-1, respectively. The catalyst was recycled many times without significant loss of activity. This journal is
Green and selective oxidation of alcohols by immobilized Pd onto triazole functionalized Fe 3O 4 magnetic nanoparticles
, Article Journal of Chemical Sciences ; 2018 ; 09743626 (ISSN) ; Naimi Jamal, M. R ; Matloubi Moghaddam, F ; Ayati, S. E ; Sharif University of Technology
2018
Abstract
Abstract: Carbonyl compounds were prepared by selective oxidation of alcohols in the presence of recoverable Fe 3O 4@ SiO 2@ Pd magnetic nanocatalyst in aqueous media as a green solvent. Molecular oxygen served as an oxidant. The catalyst was removed from the reaction media by external magnetic field, washed with methanol, and reused for six more times without any considerable reduction in its reactivity. The chemoselectivity and regioselectivity of the catalyst can serve for selective oxidation of primary alcohols in the presence of secondary ones, and for oxidation of unhindered alcohols in the presence of hindered ones. Graphical Abstract: Selective and facile oxidation of alcohols to...
Suzuki–Miyaura coupling reaction in water in the presence of robust palladium immobilized on modified magnetic Fe3O4 nanoparticles as a recoverable catalyst
, Article Applied Organometallic Chemistry ; Volume 32, Issue 2 , 2018 ; 02682605 (ISSN) ; Naimi Jamal, M. R ; Moghaddam, F. M ; Ayati, S. E ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
Aryl halides and especially inactive aryl chlorides were coupled to benzenoid aromatic rings in a Suzuki–Miyaura coupling reaction in the absence of organic solvents and toxic phosphine ligands. The reaction was catalysed by a recoverable magnetic nanocatalyst, Pd@Fe3O4, in aqueous media. This method is green, and the catalyst is easily removed from the reaction media using an external magnetic field and can be re-used at least 10 times without any considerable loss in its activity. The catalyst was characterized using scanning and transmission electron microscopies, thermogravimetric analysis, inductively coupled plasma spectroscopy, Fourier transform infrared spectroscopy, CHN analysis,...
Determination of Optimum Material and Thickness of Filter Based on Radiation Energy in Digital Industrial Radiography (CR) Using MCNP Monte Carlo Simulation Code
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Rokrok, Behrouz (Supervisor) ; Movafeghi, Amir (Co-Supervisor)
Abstract
In this study, the effect of external filter on the various parameters of image quality in digital industrial radiography by CR method for steel and aluminum piece has been investigated. The filter reduces the noise of scattered beams by absorbing the low-energy beams in the X-ray spectrum that are most likely to be scattered, but high filter thicknesses can attenuate the more energetic beams and have a negatively effect on the image quality. On the other hand, the absorption of those low-energy beams increases the average spectrum energy and thus reduce the contrast, so it is necessary to use the appropriate material and thickness of the filter. For this purpose, to examine the filter...
Organocopper-based magnetically recoverable and reusable nanocatalyst for efficient synthesis of novel 1,2,3-triazole-based sulfonamides in green medium
, Article Research on Chemical Intermediates ; Volume 44, Issue 1 , 2018 , Pages 601-612 ; 09226168 (ISSN) ; Sadighian, H ; Arabgari, M ; Mirjafary, Z ; Ayati, S. E ; Najafi, E ; Matloubi Moghaddam, F ; Sharif University of Technology
Springer Netherlands
2018
Abstract
Abstract: We report robust green synthesis of novel 1,2,3-triazole-based sulfonamides bearing different motifs such as fluorine under click conditions in presence of a copper-based magnetically recoverable and reusable heterogeneous nanocatalyst. The organocopper catalyst at 0.5 mol.% was highly recyclable (up to five times) when recovered using an external magnet without significant loss in catalytic activity. The mild reaction conditions and excellent yields (69–95 %) make this protocol an attractive method for efficient synthesis of the title compounds. The structure of product 3a was determined by Röntgen crystal structure analysis. Graphical Abstract: [Figure not available: see...