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    Crystallization behavior of mica glass-ceramics with nanophase structure

    , Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 42, Issue 3 , 2012 , Pages 420-423 ; 15533174 (ISSN) Ghasemzadeh, M ; Nemati, A ; Sharif University of Technology
    2012
    Abstract
    The influence of Zr 2 on the crystallization behavior, microstructure, and machinability of SiO 2-Al 2O 3-MgO-K 2O-B 2O 3-F glasses was investigated. The crystallization of the glass-ceramic was markedly affected by addition of ZrO 2. These glasses crystallize more rapidly. The number of mica crystals increases, whereas the size of the mica crystals decreases drastically. Machining of these glass-ceramics was found to be good, as confirmed by a drilling test using conventional steel tools. Such mechanical properties are attributable to the microstructure of these glass-ceramics. Very fine crystals are homogeneously distributed in glass matrix  

    Role of MgF2 on properties of glass-ceramics

    , Article Bulletin of Materials Science ; Volume 35, Issue 5 , October , 2012 , Pages 853-858 ; 02504707 (ISSN) Ghasemzadeh, M ; Nemati, A ; Sharif University of Technology
    Springer  2012
    Abstract
    Formation of machinable glass-ceramic in the system MgO-SiO 2-Al2O3-K2O-B2O 3-F with and without addition of MgF2 has been investigated. Crystallization of glass sample was done by controlled thermal heat treatment at nucleation and crystallization temperatures. The results showed that MgF2 in high concentration had a synergistic effect and enhanced the formation of interlockedmica crystals. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses were changed in the range of 235-405 kJ/mol, while the crystallization activation energies of samples with addition of MgF2 were changed in the range of 548-752 kJ/mol  

    Effect of different additives on the properties of alumina-spinel castables

    , Article Ceramica ; Volume 58, Issue 348 , 2012 , Pages 489-494 ; 03666913 (ISSN) Ghasemzadeh, M ; Nemati, A ; Sharif University of Technology
    2012
    Abstract
    Physical properties of low cement castable containing 22 wt.% Al 2O3-rich MgO-Al2O3 spinel and 1.7 wt.% CaO with addition of polyacrylates, castament FS20, TPP and citric acid were investigated. Results showed castables including castament FS20 have higher flow values and better final properties comparing with castables including Darvan 7S and TPP. Also in this study we investigated the effect of addition of microsilica up to 4 wt.% on the properties of alumina-spinel castables. Microsilica is the finest particles in the system and due to suitable distribution of microsilica among other particle the open porosity reduced and mechanical strength increased. Slag penetrations resistance... 

    The effects of CaF2 in mica glass-ceramics

    , Article Defect and Diffusion Forum ; Volume 334-335 , 2013 , Pages 258-263 ; 10120386 (ISSN) ; 9783037856628 (ISBN) Ghasemzadeh, M ; Nemati, A ; Sharif University of Technology
    2013
    Abstract
    Different concentrations of CaF2 were incorporated in mica glass-ceramics to evaluate their effects on the crystallization and microstructure. The kinetics of phase transformations, and the microstructures of the final crystalline phase were found to be dependent on the concentration of nucleation agents. The results showed that CaF2 in high concentration had a synergistic effect and enhanced the formation of interlocked mica crystals. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses were changed in the range of 235-405 kJ/mol, while the crystallization activation energies of samples with addition of CaF2 were changed in the range of 419-747... 

    Design and Synthesis of Heterogeneous Nano Catalyst Based on Immobilized Palladium Metal on Double Network Hydrogel and Its Application in Organic Reactions

    , M.Sc. Thesis Sharif University of Technology Ghasemzadeh, Solmaz (Author) ; Pourjavadi, Ali (Supervisor)
    Abstract
    In the past few decades, many attempts have been made to combine the benefits of homogeneous and heterogeneous catalysts. The immobilization of homogeneous catalysts onto the surface of heterogeneous supports is the result of such efforts. In this research, immobilized heterogeneous catalysts were designed and synthesized based on double network hydrogels, which produce from interpenetrating of two biocompatible and biodegradable polymer networks. In order to provide magnetic responsibility and easy separation of catalyst from the reaction mixture, the magnetic nanoparticles were dispersed onto the surface of double network hydrogel. Finally, various metal nanoparticles such as palladium and... 

    A Model for Network Telescope on White IP Address Space

    , M.Sc. Thesis Sharif University of Technology Ghasemzadeh, Hamed (Author) ; Kharrazi, Mehdi (Supervisor)
    Abstract
    Network Telescopes are used to extract security features of large a?a?s targeted large net-works.In this method all tra?cs received targeted to an unused address blo? are processedto ?nd useful informations about descriptive parameters of work propagation.Currently all resear?es are focused on dark addresses or unused address blo?s, in this re-sear? the idea is generalized to cover used and white address blo?s. Also the structure ofnetwork telescope is de?ned with a new manner whi?added more details to prediction andestimation methods. To extract security features of a?a?events, a newmethod have been introduced for inferenceabout a?a? parameters. ?e proposed method may be used to predict... 

    Design and Performance Optimization of a Diverterless Supersonic Inlet

    , M.Sc. Thesis Sharif University of Technology Ghasemzadeh, Abolfazl (Author) ; Farahani, Mohammad (Supervisor)
    Abstract
    One of the most modern types of inlets in aircraft is the Diverterless supersonic inlet, which is used in some new UAVs and fighters, and has many advantages over other types of inlets, especially in removing the boundary layer. The most important part of DSI design is the creation of bump geometry, which requires special precision and elegance. There are various methods for designing and creating bump geometry, some of which are mentioned in this report, and finally the method of creating bump geometry is selected based on the flow around the primary cone, which is in accordance with the analytical method and is in fact the most basic and widely used method.In this study, a DSI with cowl... 

    Effects of nucleation agents on the preparation of transparent glass-ceramics

    , Article Journal of the European Ceramic Society ; Volume 32, Issue 11 , August , 2012 , Pages 2989-2994 ; 09552219 (ISSN) Ghasemzadeh, M ; Nemati, A ; Baghshahi, S ; Sharif University of Technology
    Elsevier  2012
    Abstract
    Formation of transparent glass-ceramic in the system MgO-SiO 2-Al 2O 3-K 2O-B 2O 3-F with and without addition of LiF and NaF has been investigated. Crystallization of glass-sample was conducted by controlled thermal heat-treatment, at determined nucleation and crystallization temperatures. In this regard, the effects of addition of LiF and NaF were investigated on the crystallization behavior and transparency of the samples. Low transmission (less than 80% at 600. nm) was observed in the basic composition (K).The addition of NaF and LiF caused more intense phase separation in the system. The results indicated that the glass-ceramic can remain transparent if fine grains with nano size are... 

    A Corporate Supply Optimizer with flow network

    , Article Scientia Iranica ; Volume 17, Issue 1 E , June , 2010 , Pages 70-83 ; 10263098 (ISSN) Sepehri, M ; Fayazbakhsh, K ; Ghasemzadeh, F ; Sharif University of Technology
    2010
    Abstract
    A holding or a multi-business corporate seeks to coordinate its supply for minimum overall costs. A Corporate Supply Optimizer (CSO), as a central entity taking advantage, of the notion of flow networks, gathers necessary operational information from members of the corporate supply chain. The CSO then guides supply chain members on ordering decisions for a minimum overall cost for the entire supply chain. Its computational engine models the entire supply chain with multiple members in four stages to satisfy customer demand. The CSO seeks a solution with minimum total costs, unlike noncooperative supply chains where individual members compete, to optimize, their local costs. The existing... 

    Salt- and pH-resisting collagen-based highly porous hydrogel

    , Article Polymer Journal ; Volume 40, Issue 2 , 2008 , Pages 94-103 ; 00323896 (ISSN) Pourjavadi, A ; Kurdtabar, M ; Ghasemzadeh, H ; Sharif University of Technology
    2008
    Abstract
    A novel approach was developed to prepare a highly porous hydrogel with superior salt- and pH-resisting properties. According to this method, synthetic comonomers, i.e. acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), were polymerized and crosslinked in the presence of hydrolyzed collagen as a natural backbone. The characterizations of hydrogels were investigated by swelling experiment, Fourier transform infrared (FT-IR) spectroscopy, acid-base titration and thermogravimetric analysis (TGA). Morphology of the samples was examined by scanning electron microscopy (SEM). Experimental results indicate that the hydrogel has an absorbency of 360 and 73-82 g/g for distilled... 

    Fast-swelling superabsorbent hydrogels from poly(2-hydroxy ethyl acrylate-co-sodium acrylate) grafted on starch

    , Article Starch/Staerke ; Volume 60, Issue 2 , 2008 , Pages 79-86 ; 00389056 (ISSN) Pourjavadi, A ; Samadi, M ; Ghasemzadeh, H ; Sharif University of Technology
    2008
    Abstract
    Fast-swelling highly porous superabsorbent hydrogels were synthesized through a rapid radical polymerization under normal atmospheric conditions. To synthesize a biopolymer-based superabsorbent hydrogel, 2-hydroxyethyl acrylate (HEA) and sodium acrylate (AANa) were grafted on the starch backbone in an aqueous solution. The graft copolymerization reaction was carried out in the presence of ammonium persulfate (APS) as an initiator and N, N′-methylenebisacrylamide (MBA) as a cross-linker in a homogeneous medium. The chemical structure of the hydrogels was confirmed by FT-IR spectroscopy and thermogravimetric analysis (TGA). The morphology of the samples was examined by scanning electron... 

    Temperature sensitive superabsorbent hydrogels from poly(N-t-butyl acrylamide-co-acrylamide) grafted on sodium alginate

    , Article Macromolecular Symposia ; Volume 274, Issue 1 , December , 2008 , Pages 177-183 ; 10221360 (ISSN) Pourjavadi, A ; Samadi, M ; Ghasemzadeh, H ; Sharif University of Technology
    2008
    Abstract
    Temperature-sensitive hydrogels based on N-t-butylacrylamide (TBA), acrylamide (AAm), and sodium alginate were prepared by free radical polymerization method. Methylenebisacrylamide (MBA) and amonium persulfate (APS) were applied as water soluble crosslinker and initiator, respectively. The chemical structure of the hydrogels was confirmed by FT-IR spectroscopy and thermogravimetric analysis (TCA) methods. Morphology of the samples was examined by scanning electron microscopy (SEM). By changing the initial TBA/AAm mole ratios, hydrogels with different swelling properties were obtained. The rate parameters were found to be 2.0, 2.4, and 3.5 min for the superabsorbents with AAm/TBA weight... 

    Synthesis, characterization and swelling behavior of chitosan-sucrose as a novel full-polysaccharide superabsorbent hydrogel

    , Article Journal of Applied Polymer Science ; Volume 109, Issue 4 , 15 August , 2008 , Pages 2648-2655 ; 00218995 (ISSN) Pourjavadi, A ; Aghajani, V ; Ghasemzadeh, H ; Sharif University of Technology
    2008
    Abstract
    A novel full-polysaccharide hydrogel was prepared by crosslinking of chitosan with periodate-oxidized sucrose. A tetraaldehyde molecule is synthesized via periodate oxidation of sucrose and then applied as a crosslinking agent to form a new hydrogel network. A mechanism for the superabsorbent hydrogel formation via reductive N-alkylation was also suggested. The structure of the hydrogel was confirmed by FTIR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). It is shown that crosslinking of chitosan can improve its thermal stability. The effects of crosslinker concentration, pH, and inorganic salt on the swelling behavior of the hydrogel were studied. The... 

    E-policy making: A system approach based on evaluting ICT's impacts

    , Article 2006 IEEE International Conference on Service Operations and Logistics, and Informatics, SOLI 2006, Shanghai, 21 June 2006 through 23 June 2006 ; 2006 , Pages 34-39 ; 1424403189 (ISBN); 9781424403189 (ISBN) Mohamadian, A ; Elahi, S ; Ghasemzadeh, F ; Sharif University of Technology
    2006
    Abstract
    Information and Communication Technologies (ICTs) are now widely accepted by developing countries as a critical tool in their efforts, so policy makers should develop ICT policies or e-policies in order to monitor and evaluate political, socio-economic and cultural impacts of ICT and also measure progress in the use of ICTs to achieve the development strategies and policies. The paper focuses on the ICT's impacts as an important part in developing e-policies, including a comprehensive model based on system approach, appropriate frameworks for determining affecting and affected elements of ICT and a conceptual framework for analyzing and prioritizing different dimensions of the society. The... 

    Requirement Management Fundamentals for an Air Transport Fleet to Investigate and Improve Airport Runway Saturation Points

    , M.Sc. Thesis Sharif University of Technology Ghasemzadeh, Alireza (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    Air transport system of each country consists of three interconnected elements (players); namely (1) Airlines, (2) Airports and (3) Air-Traffic Control. Any increase in the air transport capacity requires consistent growth in each sector. Obviously, any player can start such a process, but cannot continue without proper contribution of the other two. In this work, we study the process of growth capacity increase in the air-transportation system with an emphasis on the Airline characteristics. We show how the growth of an independent Airline will lead to the condition for which any subsequent investment will not have any effect on the quality of services provided by the system. We refer to... 

    The Impact of Climate Change on Iran’s Agricultural Sector

    , M.Sc. Thesis Sharif University of Technology Ziaeian Ghasemzadeh, Negar (Author) ; Vesal, Mohammad (Supervisor)
    Abstract
    Agriculture consists a significant share in the economies of developing countries, and since temperatures and precipitation are considered to be the inputs for crop production, climate change has a direct impact on the agricultural sector. In this study, we are investigating the effect of climate change on the production and yield of crops in Iran, and for this purpose, we have used annual changes in temperature, precipitation, production, and yield of crops taking into account the fixed effects of year and district. To do this, we have used the panel data of districts between 1993 and 2015 regarding temperature and precipitation, the area under cultivation, and the amount of crops.... 

    A novel and low-energy PKC-based key agreement protocol for WSNs

    , Article 2013 10th International ISC Conference on Information Security and Cryptology, ISCISC 2013 ; 2013 Ghasemzadeh, H ; Aref, M. R ; Payandeh, A ; Sharif University of Technology
    IEEE Computer Society  2013
    Abstract
    Security is a critical and vital task in WSNs. Recently, key management as the core of a secure communication has received lots of attention, but in most of the proposed methods security has been compromised in favor of reducing energy consumption. Consequently, perfect resiliency has not been achieved by most of the previous works. Hostile environment, ability of adversary to capture the nodes, and dead nodes with sensitive data scattered in the region, calls for a more secure and yet practical method. This paper proposes a novel authentication scheme based on broadcast messages from BS to improve security of key management system. Through simulation it is shown that energy consumption of... 

    Labeling Video Signal Obtained from an Event Camera

    , M.Sc. Thesis Sharif University of Technology Ghasemzadeh, Mehdi (Author) ; Bagheri Shouraki, Saeed (Supervisor)
    Abstract
    Event cameras are bio-inspired sensors. They have outstanding properties compared to frame based cameras: high dynamic range (120 vs 60), low latency, no motion blur. Event cameras are appropriate for using in challenging scenarios such as vision system in self-driving cars and they have been used for high level machine vision tasks such as semantic segmentation, depth estimation. In this project, we worked on semantic segmentation using an event camera for self-driving cars. i) We introduce a large dataset, our dataset was produced using Carla simulator and it contains RGB images, events and semantic segmentation labels. ii) This project introduces new event based semantic segmentation... 

    A queueing approach to production-inventory planning for supply chain with uncertain demands: Case study of PAKSHOO Chemicals Company

    , Article Journal of Manufacturing Systems ; Volume 29, Issue 2-3 , July , 2010 , Pages 55-62 ; 02786125 (ISSN) Teimoury, E ; Modarres, M ; Ghasemzadeh, F ; Fathi, M ; Sharif University of Technology
    2010
    Abstract
    In some industries such as the consumable product industry because of small differences between products made by various companies, customer loyalty is directly related to the availability of products required at that time. In other words, in such industries demand cannot be backlogged but can be totally or partly lost. So companies of this group use make-to-stock (MTS) production policy. Therefore, in these supply chains, final product warehouses play a very important role, which will be highlighted by considering the demand uncertainty as it happens in real world, especially in the consumable product industries in which demand easily varies according to the customer's taste variation,... 

    Classification of sleep stages based on LSTAR model

    , Article Applied Soft Computing Journal ; Volume 75 , 2019 , Pages 523-536 ; 15684946 (ISSN) Ghasemzadeh, P ; Kalbkhani, H ; Sartipi, S ; Shayesteh, M. G ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Sleep study is very important in the health since sleep disorders affect the productivity of individuals. One of the important topics in sleep research is the classification of sleep stages using the electroencephalogram (EEG) signal. Electrical activities of brain are measured by EEG signal in the laboratory. In real-world environments, EEG signal is also used in portable monitoring devices to analyze sleep. In this study, we propose an efficient method for classification of sleep stages. EEG signals are examined by a new model from autoregressive (AR) family, namely logistic smooth transition autoregressive (LSTAR) to study sleep process. In contrast to the AR model, LSTAR is a non-linear...