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Performance and Rheological Characteristics of Modified Binders
, M.Sc. Thesis Sharif University of Technology ; Tabatabaee, Nader (Supervisor)
Abstract
The ever increasing usage of modified binders in road construction requires that the effect of different modifiers on the performance characteristics of the asphalt binder be determined through laboratory testing. The current Superpave protocol for performance grading asphalt binders has proven to be insufficient to properly characterize modified binders, thus researchers have searched for other testing methods to complement or possibly replace some of the Superpave tests. Most notable are the time sweep test for fatigue resistance, the multiple stress creep and recovery test (MSCR) for rutting resistance and the direct tension test (DTT) for low temperature cracking characteristics. In the...
Low Temperature Performance Evaluation of Modified Asphalt Binders
, M.Sc. Thesis Sharif University of Technology ; Tabatabaei, Nader (Supervisor)
Abstract
Low temperature cracking is the most important type of asphalt pavement distress that occurs in cold climates. Up until the development of performance grading (PG) based binder specification, there was no irect indication of low temperature suitability of asphalt binders. PG specification was mainly developed for and validated by neat binders.
With increased use of modified asphalt binders in recent years, some of the limitations and shortcomings of the original PG specifications have surfaced.Considering that low temperature cracking is a fracture failure, it was hypothesized that tests based on the fracture mechanics and fracture energy parameter can lead to better classification of...
With increased use of modified asphalt binders in recent years, some of the limitations and shortcomings of the original PG specifications have surfaced.Considering that low temperature cracking is a fracture failure, it was hypothesized that tests based on the fracture mechanics and fracture energy parameter can lead to better classification of...
Microstructure Investigation of Low Temperature Carburized Precipitation Hardenable 17-4 And 13-8 Mo Stainless Steels
, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous (Supervisor)
Abstract
Recently, low temperature carburizing of stainless steels, especially austenitic stainless steels, have been considered by so many researchers. The improvement of tribological properties of which is so impressive so much so that such properties like hardness and wear resistance increase to manifold. In this research, low temperature carburizing was done on two kinds of precipitation hardenable stainless steels 17-4 and 13-8 Mo. After that, microstructural investigations were done on the carburized surfaces and in 5, 10, 20, 80, and 150 micrometer depths. Moreover, in each depth, in order to phase structure and tribological properties investigation, XRD and microhardness tests were done,...
Experimental and Numerical Study on Reactivity Controlled Compression Combustion Ignition Natural Gas-diesel
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Vahid (Supervisor)
Abstract
According to limitation of fossil fuel consumption and cost, reduction of fuel consumption is very important in internal combustion engine. This requirement becomes twofold in light of the greenhouse effect of CO2 on global warming. Therefore, the use of engines with less fuel consumption is a global success. Diesel engines are among the most productive internal combustion engines. They have a lower fuel economy and carbon monoxide. But unfortunately, these engines respectively in rich and dilute blend have highly soot and nitrogen oxides. One of the methods in the development of the combustion process is the low temperature combustion method, which reduces the production of Knox due to low...
On the Microstructure and Mechanical Properties of Aluminum after Low-temperature Multi-directional Forging
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Severe Plastic Deformation (SPD) has been used as an effective approach to access fine grain (FG) and ultra-fine grain (UFG) materials.the Temperature of SPD is a dominant parameter to controlling ultimate properties. SPD at room-temperature and the high temperature was used widely in literature but the low-temperature process (sub-zero and cryogenic temperatures) was not used comparably. In this study, Low-temperature Multi-Directional Forging (LMDF) was applied on commercially pure aluminum and room-temperature MDF (RMDF) was attained for contrast temperature effects, and resulting in more fine grains. The grain refinement was attributed to the fragmentation process with a limitation in...
Investigation and Accomplishment of CO2 Capturing with Solid Sorbent
, M.Sc. Thesis Sharif University of Technology ; Safekordi, Ali Akbar (Supervisor)
Abstract
Carbon dioxide emissions account for 80% of current greenhouse gas emissions that contribute to global warming; this majority stake held by carbon dioxide indicates that reduction in its release to the atmosphere and capturing emissions accomplished is imperative in conservation of human life in earth. The aim of this project is CO2 capturing from ambient air to decrease air pollution with uses building surface that is wide available surface, as basis of adsorbent. In this research, we select CaO as absorbent that it is proven good absorbent in high temperature for CO2. We studied this absorbent in low temperature and pressure. We experimented different weight amount of sorbent 2,3,4,5,6.5...
CFD Modeling of PCCI Combustion for early Direct Injection of Diesel Fuel
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Vahid (Supervisor) ; Taghizadeh Manzari, Mehrdad (Supervisor)
Abstract
At today’s crowded world, the importance of automobile transportation is obvious for all. Due to energy crisis and air pollution problems, designing and manufacturing high-performance and low emission engines is very important. Because of high efficiency and low fuel consumption, diesel engines have attracted more attention. In addition to the mentioned advantages, diesel engine’s nitrogen oxide and particulate matter emissions are very high. So to limit these pollutants, strict standards was legislated by different countries and nations. Recently in the field of diesel engines emission reduction, low temperature combustion concept is proposed that can reduce nitrogen oxide and particulate...
Evaluation of Warm Mix Asphalt containing Sasobit
, M.Sc. Thesis Sharif University of Technology ; Tabatabaee, Nader (Supervisor)
Abstract
Warm mix asphalt has received considerable attention over the past decade particularly due to its potential environmental benefit such as lower energy consumption and emission, its ability to be placed at lower ambient temperatures making it a suitable material for areas with short construction season. There are three warm mix asphalt (WMA) techniques are available; organic additive, foaming, and chemical additive. This study examined Sasobit, a micro crystalline wax which is an organic additive. The concentrations tested were 1.5, 2.5 and 3.5 percent of the base binder. A PG 64-22 asphalt binder from an Iranian refinery (Tehran refinery) was used as the base binder. Superpave binder...
Design and Optimization of Helium Recovery Process from Natural Gas
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor) ; Farhanieh, Bijan (Co-Supervisor)
Abstract
Helium is a valuable substance that is widely used in industry and medicine because of its unique properties. Due to the increasing demand for helium in the global market, several helium extraction units have been launched in the world in recent years; Nevertheless, there is still a significant gap between projected global helium production capacity and demand. Today, natural gas is known as the main source of helium on the earth. The method of industrial extraction of helium from natural gas is cryogenic. Due to the low temperature of this process, relatively high power consumption is used to extract helium from natural gas. Therefore, the optimization of this process is of great...
Numerical and Experimental Analysis of Homogeneous Charge Compression Ignition with Normal Paraffins, Branched-chain Paraffins and Aromatics Combined Fuels
, Ph.D. Dissertation Sharif University of Technology ; Hosseini, Vahid (Supervisor) ; Mozafari, Ali Asghar (Supervisor)
Abstract
The purpose of this dissertation is to experimentally and numerically investigate the effect of molecular structure, composition, and physical and chemical properties of fuel on HCCI combustion. A well-equipped laboratory was set up to perform the required tests, capable of performing HCCI tests with different fuels. All tests used a single-cylinder diesel engine modified to operate in HCCI mode. Also, for numerical simulation, a chemical kinetic multi-zone model was developed to predict HCCI combustion behavior with appropriate accuracy. To investigate the effect of fuel chemical structure on HCCI combustion, three fuels, toluene, iso-octane and normal heptane, with entirely different...
SnO2 Layer Curing as a Low Temperature Electron Transporting Layer in Perovskite Solar Cell
, M.Sc. Thesis Sharif University of Technology ; Taghavinia, Nima (Supervisor)
Abstract
Perovskite solar cells have attracted much attention due to their high photovoltaic performance. The excellent performance of perovskite solar cells is attributed to the superior electrical properties of each layer, including the electron-transporting layer, the light-absorbing layer, and the hole-transporting layer. The electron transport layer plays a key role in influencing the photovoltaic parameters of perovskite solar cells. SnO2 is considered as an ideal electron transport layer for perovskite solar cells due to its high carrier mobility, deep conduction band, suitable band gap and low temperature processing. Surface modification of SnO2 has significantly improved device performance...
Experimental and Numerical Investigations of Reactivity Controlled Compression Ignition (RCCI)Combustion Fueled by Diesel and Natural Gas
, Ph.D. Dissertation Sharif University of Technology ; Hosseini, Vahid (Supervisor) ; Shamloo, Amir (Supervisor)
Abstract
In this thesis, reactivity controlled compression ignition (RCCI) combustion fueled by diesel and natural gas is experimentally and numerically investigated. Natural gas as a fuel with low reactivity is injected into the intake manifold, and diesel as a fuel with high reactivity is injected directly into the combustion chamber. One of the main goals of this thesis is to experimentally examine the effect of important parameters on combustion phasing control, operational range extension, and pollutants. Natural gas is one of the important sources of energy in Iran and the world. Using natural gas in internal combustion engines can cause methane to slip into the atmosphere and intensify the...
Experimental Study of the Conversion of Heat to Electricity Using Movement of a Magnet Inside an Oscillating Heat Pipe
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
Heat sources with temperatures less than 100 °C are available in various processes in the form of waste heat and from renewable sources such as solar energy. One of the methods of gaining benefit from these ubiquitous and abundant heat sources is using thermal harvesters that convert low-temperature heat into electrical energy without the need for the power grid. Portable harvesters can be a reliable and low-cost option for providing stable energy for low-power electronic devices such as wireless sensors. Many studies have been conducted at the global level to design and develop efficient low-temperature heat harvesting mechanisms. However, each of them is associated with fundamental...
Efficient, hysteresis-free, and flexible inverted perovskite solar cells using all-vacuum processing.Efficient, hysteresis-free, and flexible inverted perovskite solar cells using all-vacuum processing
, Article Solar RRL ; 2020 ; Yadav, P ; Prochowicz, D ; Tavakoli, R ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
The fabrication of efficient perovskite solar cells (PSCs) using all-vacuum processing is still challenging due to the limitations in the vacuum deposition of the hole transporting layer (HTL). Herein, inverted PSCs using copper (II) phthalocyanine (CuPC) as an ideal alternative HTL for vacuum processing are fabricated. After proper optimization, a PSC with a power conversion efficiency (PCE) of 20.3% is achieved, which is much better than the PCEs (16.8%) of devices with solution-based CuPC. As it takes a long time to dissolve CuPC in the solution-based device, the evaporation approach has better advantage in terms of fast processing. In addition, the device with the evaporated CuPC HTL...
Design of a novel HSLA steel with a combination of high strength (140-160 ksi) and excellent toughness
, Article International Journal of Materials Research ; Volume 112, Issue 10 , 2021 , Pages 800-811 ; 18625282 (ISSN) ; Ghazvinian, S ; Amirsalehi, M ; Momeni, A ; Sharif University of Technology
Walter de Gruyter GmbH
2021
Abstract
Three steels were designed based on HSLA-100 with additional levels of Mn, Ni, Cr and Cu. The steels were prepared by controlled rolling and tempered at temperatures in range of 550-700°C. The continuous cooling time curves were shifted to longer times and lower temperatures with the increased tendency for the formation of martensite at lower cooling rates. The microstructures revealed that controlled rolling results in austenite with uniform fine grain structure. The steel with the highest amount of Mn showed the greatest strength after tempering at 750 °C. The top strength was attributed to the formation of Cu-rich particles. The steel with 1.03 wt.% Mn, tempered at 650 °C exhibited the...
Experimental and numerical investigation of low-temperature performance of modified asphalt binders and mixtures
, Article Road Materials and Pavement Design ; 2016 , Pages 1-22 ; 14680629 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This...
Insights into application of acorn shell powder in drilling fluid as environmentally friendly additive: filtration and rheology
, Article International Journal of Environmental Science and Technology ; Volume 18, Issue 4 , 2021 , Pages 835-848 ; 17351472 (ISSN) ; Ramezani Saadat Abadi, A ; Rukavishnikov, V ; Minaev, K ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
Conventional additives used in drilling fluid may have detrimental short- and long-term impacts on the surrounding environment. The employment of biodegradable green material in drilling fluid as alternative additives will eliminate these harmful impacts. In this study, acorn shell powder is proposed as a novel biodegradable additive for application in drilling fluid. First, the acorn shell powder was prepared and then characterized in terms of chemical structure, particle size, and morphology. The acorn shell powder, with four different concentrations, was then introduced into a water-based fluid; its functionality in the fluid system was evaluated with respect to rheological and filtration...
Tailoring of morphology and crystal structure of nanomaterials in MgO-TiO 2 system by controlling Mg:Ti molar ratio
, Article Journal of Sol-Gel Science and Technology ; Volume 64, Issue 1 , October , 2012 , Pages 135-144 ; 09280707 (ISSN) ; Fray, D. J ; Sharif University of Technology
Springer
2012
Abstract
The morphological manipulation and structural characterisation of TiO 2-MgO binary system by an aqueous particulate sol-gel route were reported. Different crystal structures including pure MgTiO 3, mixtures of MgTiO 3 and TiO 2 and mixtures of MgTiO 3 and Mg 2TiO 4 were tailored by controlling Mg:Ti molar ratio and annealing temperatures as the processing parameters. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that all compounds crystallised at the low temperature of 500 °C. Furthermore, it was found that the average crystallite size of the compounds depends upon the Mg:Ti molar ratio as well as the annealing temperature, being in the range 3-5 nm at...
Insights into application of acorn shell powder in drilling fluid as environmentally friendly additive: filtration and rheology
, Article International Journal of Environmental Science and Technology ; 2020 ; Ramazani S. A, A ; Rukavishnikov, V ; Minaev, K ; Sharif University of Technology
Springer
2020
Abstract
Conventional additives used in drilling fluid may have detrimental short- and long-term impacts on the surrounding environment. The employment of biodegradable green material in drilling fluid as alternative additives will eliminate these harmful impacts. In this study, acorn shell powder is proposed as a novel biodegradable additive for application in drilling fluid. First, the acorn shell powder was prepared and then characterized in terms of chemical structure, particle size, and morphology. The acorn shell powder, with four different concentrations, was then introduced into a water-based fluid; its functionality in the fluid system was evaluated with respect to rheological and filtration...
An investigation on perpetual asphalt pavements in Minnesota
, Article International Journal of Pavement Research and Technology ; Volume 13, Issue 3 , 2020 , Pages 247-254 ; Sharif University of Technology
Springer
2020
Abstract
Asphalt Pavement Alliance (APA) created the Perpetual Pavement Award program in 2001. This program requires that the roadway has at least 35 years of service at the time of award and had experienced no structural failures. In addition, the program limits candidate roadways to those that have not received more than 100 mm of new asphalt nor have been resurfaced at a frequency exceeding 13 years. Minnesota Department of Transportation (MnDOT) currently owns the record for the most award winners and has received an award every year from 2002 through 2017. This study reviews all the award-winning roadways in Minnesota to determine common material, design factors and considerations which may have...