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Effect of deep cryogenic treatment on wear resistance and tool life of M2 HSS drill
, Article Journal of Materials Processing Technology ; Volume 206, Issue 1-3 , 12 September , 2008 , Pages 467-472 ; 09240136 (ISSN) ; Nejati, E ; Khomamizadeh, F ; Sharif University of Technology
2008
Abstract
The influence of deep cryogenic treatment on wear resistance and tool life of M2 HSS drills in high-speed dry drilling configuration of carbon steels was studied. The experimental results indicated 77 and 126% improvement in cryogenic-treated and cryogenic- and temper-treated drill lives, respectively. The results of wear rate test were in agreement with drill life test. Chemical composition of chips were also reported to show the onset of seizure in drilling test and the consequence of seizure in promoting dissolution wear by diffusion mechanism. Wear resistance improvement was mainly attributed to the resistance of cryogenically treated drills against diffusion wear mechanism, due to the...
Sol-gel nanostructured titanium dioxide: Controlling the crystal structure, crystallite size, phase transformation, packing and ordering
, Article Microporous and Mesoporous Materials ; Volume 112, Issue 1-3 , 2008 , Pages 392-402 ; 13871811 (ISSN) ; Fray, D. J ; Mohammadi, A ; Sharif University of Technology
2008
Abstract
The anatase phase of titania was stabilised with physically modifying particulate sol-gel process. Two major parameters, peptisation temperature and drying temperature, were identified which were responsible for retarding the anatase to rutile phase transformation, crystal growth and packing of primary particles. The critical nucleus size of transformation was controlled by natural (at 25 °C) and artificial (at 50 and 70 °C) peptisation techniques. Moreover, sintering of primary particles was controlled by cool (at 0 and 5 °C) and normal (at 25 °C) drying techniques. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that a full conversion of titanium isopropoxide is obtained...
Crack-free nanostructured BaTiO3 thin films prepared by sol-gel dip-coating technique
, Article Ceramics International ; Vol. 40, issue. 6 , 2014 , pp. 8613-8619 ; Nemati, A ; Sasani Ghamsari, M ; Sharif University of Technology
Abstract
In this report, crack-free nanostructured barium titanate thin films are prepared by a sol-gel processing method. Glacial acetic acid, barium acetate, titanium tetraisopropyl alkoxide, 2-propanol and deionized water are used as precursors for preparing stable precursor solution. Then very thin films (thickness=26 nm) are deposited on fused silica substrates. In order to prepare crack-free thin films of BaTiO3, much attention is given to solvent evaporation process and a controlled pre-drying process is developed. It is found that the control of the process, especially in the initial stage of drying process is crucial and important for preparation of the crack-free ultrathin nanostructured...
A dynamic thermal based reliability model of cast-resin dry-type transformers
, Article 2010 International Conference on Power System Technology: Technological Innovations Making Power Grid Smarter, POWERCON2010, 24 October 2010 through 28 October 2010 ; 2010 ; 9781424459407 (ISBN) ; Bigdeli, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
Abstract
In this paper, some models have been introduced for dynamic thermal modeling of cast-resin transformers which are based on genetic algorithm. A typical 400kVA cast-resin transformer has been selected and the model parameters are estimated and validated with the help of experimental data extracted from different load cycles. The estimated models are used to generate a reliability model for cast-resin dry-type transformers and the effects of variation in load, ambient temperature and atmosphere conditions on the reliability of castresin transformer are illustrated. As it will be shown in this paper, the effects of working conditions on the life-time of insulation in dry-type transformers is...
Drying shrinkage in alkali-activated binders – A critical review
, Article Construction and Building Materials ; Volume 190 , 2018 , Pages 533-550 ; 09500618 (ISSN) ; Kinnunen, P ; Dalvand, A ; Mohammadi Firouz, R ; Illikainen, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Alkali-activated binders have been proposed and have emerged as an alternative to ordinary Portland cement (OPC) binders with acceptable mechanical and durability performances in addition to positive environmental impacts. These alternative binders use a wide range of aluminosilicate precursors, with differing availabilities, reactivities, costs and CO2 emissions. Despite all the studies published on improving the characteristics of these materials in the last decades, some aspects of alkali-activated binders require further investigations. For instance, shrinkage in alkali-activated binders due to the different chemical processes being involved is more complicated than OPC composites and it...
Performance of glued-in rod timber joints under seawater and UV exposure cycles
, Article Construction and Building Materials ; Volume 322 , 2022 ; 09500618 (ISSN) ; Shakiba, M ; Yekrangnia, M ; Tannert, T ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Timber joints with glued-in rod connections provide an interesting technical solution for numerous structural applications, also under harsh environmental conditions; yet little research is available on this topic. This paper experimentally investigated the effect of exposure to seawater wetting/drying cycles and seawater wetting/drying plus UV radiation cycles on the pull-out performance of glued-in rod timber connections. Three rod diameters, three anchorage lengths, and four exposures were considered, leading to manufacturing and testing a total of 189 specimens. The quasi-static monotonic pull-out resistance of joints was a function of rod diameter and anchorage length as well as...
Effect of rare-earth promoters (Ce, La, Y and Zr) on the catalytic performance of NiO-MgO-SiO2 catalyst in propane dry reforming
, Article Molecular Catalysis ; Volume 522 , 2022 ; 24688231 (ISSN) ; Rezaei, M ; Kazemeini, M ; Farhadi, F ; Keshavarz, A. R ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In this contribution, NiO-MgO-SiO2 catalysts containing 3 wt. % of CeO2, La2O3, Y2O3, and Zr2O3 were examined for propane dry reforming at 550-750 °C. The samples were synthesized by a co-precipitation route, followed by a hydrothermal treatment, and characterized by BET, XRD and TPX analyses. The results indicated that the addition of promoters enhanced the metal-support interaction and basic characteristics, while the acidic nature of the promoted catalyst was changed in a different way. The highest propane conversion of 39.6% was observed over Ce-promoter sample, while the un-promoted catalyst possessed a value of 36.8% at 700 °C. Nevertheless, La and Y-promoted catalysts possessed a...
An intelligent approach for improved predictive control of spray drying process
, Article INES 2010 - 14th International Conference on Intelligent Engineering Systems, Proceedings, 5 May 2010 through 7 May 2010, Las Palmas of Gran Canaria ; 2010 , Pages 127-136 ; 9781424476527 (ISBN) ; Neshat, N ; Saberi, M ; Sharif University of Technology
2010
Abstract
A flexible meta modelling approach is presented to predictive control of a drying process using Adaptive Neuro-Fuzzy Inference System (ANFIS), Artificial Neural Network (ANN) and Partial Least Squares (PLS) analysis. In the proposed approach, the PLS analysis is used to pre-process actual data and to provide the necessary background to apply ANN and ANFIS approaches. A reasonable section of this study is assigned to the modelling with aim at predicting the granule particle size and executing by ANFIS and ANN. ANN hold the promise of being capable of producing non-linear models, being able to work under noise conditions and being fault tolerant to the loss of neurons or connections. Also, the...
Effect of drying conditions on the catalytic performance, structure, and reaction rates over the Fe-Co-Mn/MgO catalyst for production of light olefins
, Article Bulletin of Chemical Reaction Engineering & Catalysis ; Volume 13, Issue 1 , 2018 , Pages 97-112 ; 19782993 (ISSN) ; Arsalanfar, M ; Mirzaei, N ; Zamani, Y ; Sharif University of Technology
Diponegoro University
2018
Abstract
The MgO-supported Fe-Co-Mn catalysts, prepared using co-precipitation procedure, were tested for production of light olefins via CO hydrogenation reaction. The effect of a range of drying conditions including drying temperature and drying time on the structure and catalytic performance of Fe-Co-Mn/MgO catalyst for Fischer-Tropsch synthesis was investigated in a fixed bed micro-reactor under the same operational conditions of T = 350 °C, P = 1 bar, H2/CO = 2/1, and GHSV = 4500 h-1. It was found that the catalyst dried at 120 °C for 16 h has shown the best catalytic performance for CO hydrogenation. Furthermore, the effect of drying conditions on different surface reaction rates was also...
A comparative study of earthquake source models in high-order accurate tsunami simulations
, Article Ocean Modelling ; Volume 141 , 2019 ; 14635003 (ISSN) ; Bonev, B ; Hesthaven, J. S ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
The discontinuous Galerkin method is used to solve the non-linear spherical shallow water equations with Coriolis force. The numerical method is well-balanced and takes wetting/drying into account. The two fold goal of this work is a comparative study of dynamic and static tsunami generation by seabed displacement and the careful validation of these source models. The numerical results show that the impact of the choice of seabed displacement model can be significant and that using a static approach may result in inaccurate results. For the validation of the studies, we consider measurements from satellites and buoy networks for the 2011 Tohoku event and the 2004 Sumatra–Andaman tsunami. The...
Rubberized alkali-activated slag mortar reinforced with polypropylene fibres for application in lightweight thermal insulating materials
, Article Construction and Building Materials ; 2020 ; Shoaei, P ; Shariati, M ; Ameri, F ; Musaeei, H. R ; Behforouz, B ; de Brito, J ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Every year, about a thousand million tires reach the end of their service life, more than half of which are disposed of in landfills. The waste tire rubber has a great potential for application as aggregate phase in production of lightweight concrete/mortar. This study is aimed at evaluating the effects of using crumb rubber (CR) as fine aggregate at replacement ratios of 0–60% (by volume) in alkali-activated slag mortars. Furthermore, polypropylene fibre (PPF) was used at 0.5% and 1% of volume of the mix to enhance the properties of mortar mixes such as flexural strength and shrinkage behaviour. The compressive strength, flexural strength, water absorption, thermal conductivity, drying...
Preparation and Surface Modification of PC Membranes for Gas Separation
, M.Sc. Thesis Sharif University of Technology ; Soltanieh, Mohammad (Supervisor) ; Goodarznia, Iraj (Supervisor)
Abstract
The gas separation properties of polycarbonate (PC) membranes were investigated in this study. These membranes were prepared via dry and dry-wet phase inversion technique. Pure O2, N2, and CO2 gases were permeated through prepared membranes. The effects of membrane preparation conditions, including solvent type, non-solvent type, non-solvent/solvent volumetric ratio, polymer weight fraction, and drying temperature on the gas separation properties of dry PC membranes were investigated using Taguchi experimental design. Taguchi analysis show that polymer weight fraction offers the most important effect on the separation characteristics of the dry PC membranes. To get the highest...
Simulation of Complex and Dry Reforming of Natural Gas to Produce Synthesis Gas And Their Technical and Economical Comparison
, M.Sc. Thesis Sharif University of Technology ; Kazemeini, Mohammad (Supervisor) ; Zamanian, Akbar (Supervisor) ; Baghalha, Morteza (Supervisor)
Abstract
In this study, two units of production of synthesis gas has been stimulated into 2 forms of natural gas complex (steam/Co2¬) reforming and dry reforming. They have been examined from technical and economical views. The product from this process is synthesis gas by the unit ratio of Hydrogen and Carbon Monoxide which is used in Arak petrochemical complex for producing 2EH. For producing this synthesis gas in 900C (reactor temperature) and 15 bar of total pressure , the ratio of feeding parts into reforming reactor for total input carbon (methane and other hydrocarbon) and Carbon dioxide gas and water vapor in representation ( [CH4 + other hydrocarbons : CO2 : H2O ] ) for complex reforming ...
Removal of Fluorine from radioactive solid waste of Esfahan Uranium Conversion Facility
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Khanchi, Alireza (Supervisor) ; Gasemi, Hosein (Co-Advisor)
Abstract
Uranium is the most important element in the nuclear fuel cycle. Recovery of uranium from waste produced at every stage of the fuel cycle is not only economically important, but also environmentally important. In the production phase of uranium hexafluoride, certain amount of solid waste is produced in the bottom of the fluorination reactor. In order to extract the uranium from this waste, we have to eliminate the fluorine contained in the waste. This is because the fluorine forms strong complex with uranyl ions during the extraction process, and prevents from efficient extraction of uranium. In the current thesis؛ first, we examined the characteristics of the waste ...
Volume Reduction of Solid Waste at Bushehr Nuclear Power Plant by Incineration Method; a Feasibility Study
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Aghabeigi, Hamid Reza (Supervisor)
Abstract
Operational wastes of nuclear power plants are classified according to their radioactivity level & physical state. According to the radioactivity level, operational wastes are divided into low level waste (LLW) & intermediate wastes (ILW); & based on physical state they are divided into 3 groups of wet solid & liquid wastes, dry solid wastes & gaseous wastes.Bushehr nuclear power plants produce 1600 barrels of waste per year, among which dry solid waste is about 40 percent. According to the physical nature & treatment methods used, the dry solid waste is further classified into combustible, non- combustible, compressible & incompressible wastes.The purposes of dry solid waste treatment is...
Studing the Performance of Rotary Dryer in Drying Enzyme Products
, M.Sc. Thesis Sharif University of Technology ; Roosta Azad, Reza (Supervisor)
Abstract
Drying is one of the important downstream processes in the production of biotechnological products. The dryer design for heat-sensitive materials such as proteins requires special process considerations. In this study, a rotary dryer evaluated for drying protein products. The used liquid enzyme as model, a bacterial α-amylase, first, immobilized on sodium sulfate and sodium tripolyphosphate as carriers in a spraying mode and then, the obtained wet solid materials containing the enzyme, dried in a batch dryer. The performance of this dryer investigated to achieve suitable properties such as the enzyme activity and the final moisture content of product by changing the process conditions....
Increasing the Stability of Enzyme by Immobilization
, M.Sc. Thesis Sharif University of Technology ; Roosta Azad, Reza (Supervisor) ; Tahmasebpoor, Maryam (Co-Supervisor)
Abstract
Almost all of the country's industrial enzyme needs are met through imports. In this regard, much attention has been paid to industrial production of detergent enzymes such as protease, lipase, amylase and cellulase. Proteases, are the most important industrial enzymes with 60% of the world's enzyme market. Extracellular alkaline proteases of microbial origin are most widely used in the laundry detergent industry to help clear protein stains on clothing caused by blood, milk, eggs, and meat. In this study, bacterial alkaline protease enzyme produced by Bacillus subtilis ATCC6633 was used as a model of functional enzymes in detergent industries.Enzyme immobilization-drying operations are one...
Drying in Spouted Beds with Draft Tube
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Simulation runs have been conducted to predict the evolution of sand drying in conical spouted beds with a non-porous draft tube. In the simulation runs, the moisture content of the solid phase was assumed to be 7 % (kg water/kg sand). The simulation results were validated against experimental results reported by Olazar et al. and good agreement was obtained.Influences of various physical and geometrical parameters such as superficial gas velocity, inlet temperature, length and diameter of draft tube and initial moisture content on the sand drying were investigated. Temperature and gas velocity are the most important parameters for improving the drying process and reduce the drying time of...
Re-Creation of Lost Gas Layer on Superhydrophobic Surfaces with Micro/Nanostructures
, M.Sc. Thesis Sharif University of Technology ; Mosavi, Ali (Supervisor)
Abstract
Due to their unique characteristics, such as drag reduction, anti-fouling, and enhancing condensation, hydrophobic and superhydrophobic surfaces have attracted a lot of attention in the past decades. Since approximately 4% of the fossil fuel usage and 14-19% of the air pollution (including greenhouse gases, sulfur, and so forth) are attributed to naval activities, and the dominant form of drag on vessels is friction, drag reduction will not only reduce the cost and usage of fossil fuels, but it will also have numerous environmental benefits
Behavior of a Four Degree of Freedom Jeffcott Rotor with Clearance and Rubbing in Supports
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Roholla (Supervisor)
Abstract
different phenomena occur between rotor and support rub impact causing system parts failure. Still Increasing the accuracy of manufacturing and decreasing the clearance of supports but the probability of rub impact between the rotor and support grows and this phenomenon is going to be more critical. This research would rub impact at two ends of four degrees of freedom Jeffcott rotor considering supports directional degree of freedom. Because the contact points are at two ends of the rotor, the rotational degree of freedom of the rotor is also considered. The system is modeled with 8-DOF and after numerical solving and comparison, the results with other papers, the system's behavior including...