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Wear behaviour of in situ Cu-Al2O3 composites produced by internal oxidation of as cast alloys
, Article Tribology - Materials, Surfaces and Interfaces ; Volume 3, Issue 3 , 2009 , Pages 125-131 ; 17515831 (ISSN) ; Abachi, P ; Purazrang, K ; Sharif University of Technology
2009
Abstract
In the present study, the wear behaviour of Cu-Al2O3 composites and Cu-Al alloys has been investigated. The experiment involved casting of Cu-Al alloys with 0•37, 1, 2 and 3 wt-% of aluminium under inert gas atmosphere. The composites were produced by internal oxidation of alloys at 950°C for 10 h in presence of Fe2O3 and Al 2O3 powders mixture. The microstructures of composites were studied using SEM and atomic force microscopy. To identify wear behaviour of specimens, dry sliding pin-on-disk wear tests were conducted according to ASTM G99-95a standard. The normal loads of 20, 30, and 40 N were applied on specimens during wear tests. The sliding speed and distances were selected as 0•5 m...
Rubberized alkali-activated slag mortar reinforced with polypropylene fibres for application in lightweight thermal insulating materials
, Article Construction and Building Materials ; Volume 270 , 2021 ; 09500618 (ISSN) ; Shoaei, P ; Shariati, M ; Ameri, F ; Musaeei, H. R ; Behforouz, B ; de Brito, J ; Sharif University of Technology
Elsevier Ltd
2021
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...
A vacuum-re lled tensiometer for deep monitoring of in-situ pore water pressure
, Article Scientia Iranica ; Volume 27, Issue 2 , 2021 , Pages 596-606 ; 10263098 (ISSN) ; Chiu, A. C. F ; Ng, C. W. W ; Jafarzadeh, F ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
Real-time measurement of soil water pressure has been recognized as an essential part of investigating water ow in unsaturated soils. Tensiometry, amongst di erent measuring techniques, is a common method for direct evaluation of water pressure. However, the lower limit of measurable water pressure by a conventional tensiometer becomes even more limited by increasing its length in the vertical installation. This paper describes the development of a Vacuum-Re lled Tensiometer (VRT) for monitoring soil water pressure independent of installation depth. This is achieved by xing the distance between pressure sensor and ceramic cup together with incorporating an ancillary vacuum-re lling assembly...
A conceptual new model for use of solar water heaters in hot and dry regions
, Article Sustainable Energy Technologies and Assessments ; Volume 49 , 2022 ; 22131388 (ISSN) ; Zarezade, M ; Khalifeh Soltani, S. R ; Hosseini Dehshiri, S. J ; Hosseini Dehshiri, S. S ; Ao Xuan, H ; Arockia Dhanraj, J ; Techato, K ; Chowdhury, S ; Issakhov, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Solar heater has been known as an application of the solar thermal energy that is commonly employed for water heating. Purpose of this research is to introduce a conceptual model for employing solar water heaters (SWHs) in Yazd, Iran. Moreover, structural equation modeling (SEM) is used for assessing effect(s) of the available parameters on the suggested model. Political-cultural-social issues, economic issues, financial support, geographic location, infrastructure, and interactions were assessed as the independent variables of the study. AMOS was used to implement the processes and design the research questionnaire. According to SEM, the dependent variable “interaction” via “economic...
Preparation of biodegradable gelatin/PVA porous scaffolds for skin regeneration
, Article Artificial Cells, Nanomedicine and Biotechnology ; Volume 45, Issue 5 , 2017 , Pages 928-935 ; 21691401 (ISSN) ; Dadbin, S ; Frounchi, M ; Rajabi, S ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
Porous scaffolds composed of gelatin/poly (vinyl alcohol), (Gel/PVA), were prepared using combination of freeze gelation and freeze drying methods. The effect of polymer concentration, gelatin/PVA ratio, and glutaraldehyde/gelatin ratio (GA/Gel) was investigated on morphology of pores, swelling ratio, biodegradation, and skin cell culture. At optimum preparation conditions the scaffolds had uniform pore size distributions showing high swelling ratio of 23.6. The scaffolds were of biodegradable nature and almost degraded in 28 days. Human dermal fibroblast cells (HDF) were cultured on the scaffolds and MTS assay was conducted to evaluate the influence of PVA on growth and proliferation of the...
Dehydration of THF Using Different Zeolites
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
The aim of this work was to investigate the performance of different kinds of Linde type A zeolite (LTA) for the dehydration of Tetrahydrofuran (THF)-water solution. Batch experiments were carried out to evaluate the effect of various operating parameters such as contact time, initial concentration, mixing temperature (10, 15,and 25 C), amount of adsorbent, and zeolite type(3A, 4A, and 5A zeolites). In theoretical studies, we took the advantage of several types of equilibrium model isotherms such as Langmuir, Freundlich, Dubin-Kaganer-Radushkevich (DKR) to describe the experimental adsorption data. Besides, three adsorption kinetic models including pseudo-first-order, pseudo-second-order,...
Fabrication and Chracatization of Novel Electrospun Chitosan Fibers Reinforced with Bacterial Cellulose and Nanodiamond for Wound Dressing Applications
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
Chronic wounds are among the serious injuries which have called the attention of scientists to invest in an effort to fabricate temporary skin grafts and wound dressing materials. One of the widely acceptable solutions to this obstacle is to design a bioactive scaffold capable of regenerating tissue as well as delivering active agents to the site specific area. To this end, natural biopolymers are considered as suitable candidates to be employed in regenerative medicine due to their excellent biocompatibility. In addition, nanoparticles possess special properties such as the ability in sequestering the drug release which make them promising candidates in the fabrication of the...
Fabrication and Characterization of Nanocomposite Bone Scaffold with Gradient Structure Based on Thermoplastic Starch
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
Tissue regeneration by bio-compatible/degradable scaffolds is one of the widely used approaches in the field of tissue engineering. In this study, a thermoplastic starch based nanocomposite scaffold with gradient structure was fabricated by unidirectional freeze drying method. To increase the stability of the scaffold in the aqueous media, PVA was added to starch solution. Then, the PVA and starch molecules were cross-linked by adding citric acid to the mixture. On the one hand, to improve the mechanical properties of the scaffold, and control its bio-degradability on the other, cellulose nano-fibers were employed. Also, the bioactivity of the scaffold was induced by using hydroxyapatite...
Impact of Hydraulic Hysteresis on Hydro-mechanical Behaviour of Infilled Fractured Rocks in Unsaturated Condition
, M.Sc. Thesis Sharif University of Technology ; Khosravi, Ali (Supervisor)
Abstract
Recent studies have shown that comprehensive characterization of the behavior of infilled rock fractures under saturated and unsaturated conditions requires knowledge of morphological details of fracture surface, as well as state of stress of infill materials and their initial innate conditions (e.g., void ratio, water content, degree of saturation and dry density). This study presents the details and typical results from a new testing approach to study the hydro-mechanical behavior of the infilled rock fractures under different stress states and saturation conditions. The new testing approach incorporates the axis translation technique for suction control, a flow pump for the measurement of...
Design of an Optimized Gas-liquid Auxiliary Heat Exchanger to Improve Performance of a Rankin Cycle Using CFD
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
The enviromental wind would cause serious drop in the performance of Heller cooling systems in thermal powerplants working on Rankin cycle. Therfore, it is necessary to consider the wind velocity in the design of such cooling tower systems. We use the computational fluid dynamics (CFD) and simulate the 3D buoyant flow passing through and over a heel cooling tower. We consider three different wind veocities of 0, 5 and 10 m/s in our simulations. In order to consider the low efficiency of the cooling system in efficiency drop of the main rankin cycle, we need to consider actual power generated by the powerplant generator, which is directly affected by the turbine back pressure. To connect the...
Investigation of Water Consumption Reduction and Exergoeconomic Analysis of Hybrid Cooling Towers
, M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Hassan (Supervisor) ; Asghari, Mohsen (Supervisor)
Abstract
Nowadays, cooling towers are widely used in power plants, refineries, petrochemicals and ventilation industries, but the water consumption of these towers is high and because of water crisis in Middle East and Iran, it is necessary to devise in order to reduce the water consumption of these towers. In this study separated hybrid cooling tower are used to investigate the water consumption at power plants. The rigorous Poppe method are used in order to estimate the exact amount of water loss due to evaporation in wet cooling towers. First, the effect of ambient condition, wet cooling tower cells and dry cooling tower size on the performance of hybrid cooling tower are investigated, then the...
Investigating the Performance of Fluidized bed Dryer in Immobilization and Drying of A-amylase Enzyme
, M.Sc. Thesis Sharif University of Technology ; Roostaazad, Reza (Supervisor)
Abstract
Enzyme immobilization/drying operations are among the important operations of many biotechnological industrial units. The enzyme used in this study is bacterial alpha-amylase, which is widely used in various industries, including detergents. The production of alpha-amylase enzyme contains a large percentage of water in its composition; therefore, a wet wall tower was designed to conduct the experiments to evaporate the water present in the enzyme liquor, analyze its effects on activity, and also to validate the device. The results showed that in a flow of air around 240m3/hr and ambient temperature of 20◦C, enzyme liquor has a 250% increase in biological activity, which indicates the...
Theoretical and Experimental Study to Conversion of AUC to UO2 by Microwave Heating
, Ph.D. Dissertation Sharif University of Technology ; Otukesh, Mohammad (Supervisor) ; Ghannadi Maragheh, Mohammad (Co-Advisor) ; Ghasemi, Mohammad Reza (Co-Advisor)Preparation of Porous PVA Nanocomposite Hydrogels Via Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
In this research, porous polyvinyl¬ alcohol (PVA)/Montmorillonite nanoclay and polyvinyl alcohol/polyvinyl pyrrolidone (PVP)/Montmorillonite nanoclay nanocomposite sponges (foams) were fabricated by freeze-drying method. The foams were crosslinked using gamma irradiation. The pore size and interconnectivity of nanocomposites characterized by scanning electron microscopy (SEM), showed bimodal pore size distribution resulting from preparation method.
SEM micrographs displayed that addition of PVP ( wt% of total solid polymer) to the PVA sponges increased the pore size and interconnectivity, due to the optimal number of hydrogen bonds between functional groups of polymeric matrices....
SEM micrographs displayed that addition of PVP ( wt% of total solid polymer) to the PVA sponges increased the pore size and interconnectivity, due to the optimal number of hydrogen bonds between functional groups of polymeric matrices....
An Experimental-Theoretical Study on Batch (Static) Sublimation and Derivation of a Correlation for its Heat Transfer Coefficient
, M.Sc. Thesis Sharif University of Technology ; Otukesh, Mohammad (Supervisor)
Abstract
The major features of batch sublimation were investigated in an experimental-theoretical study. An experimental setup with real-time displays, sublimated dry ice blocks of different sizes, with circular or rectangular geometries. When temperature of hotplate was changed from -30 to 200 oC, heat transfer coefficient “hsub” decreased from 126 to 70 W/m2K, while thermal flux increased, linearly. Weight and area of the block had a positive/negative effects on “hsub”, respectively. In theoretical part, at first, two “linear-gradient” and “cubic” models were developed by a combined mass-momentum-energy balance. The latter used Von Karman temperature profile, and in cases of circular and...
Experimental Modeling of a Transparent Fuel Cell with Aid of Deep Neural Network to Measure Water Coverage Ratio and Fuzzy Control
, M.Sc. Thesis Sharif University of Technology ; Alasty, Aria (Supervisor) ; Kermani, Mohammad Jafar (Supervisor) ; Boroushaki, Mehrdad (Co-Supervisor)
Abstract
Polymer membrane fuel cell is a rich source of renewable energy. Two problems of short life and low reliability in fuel cells are the main problems of this system. The difference in partial pressure of hydrogen and oxygen causes serious damage to the fuel cell and inefficiency of the electricity production capacity. On the other hand, the life and optimal performance of the fuel cell depends on the moisture content of the membrane because the membrane needs sufficient moisture to pass ions. Transparent fuel cells can be used to study the water in the fuel cell. With direct imaging of this type of fuel cells, the phenomenon of water creation in the fuel cell can be studied with the help of...
Laboratory Investigation of the Effects of Sodium Chloride Concentration on Soil Water Retention Curve and Volumetric behavior Using an Unsaturated Automatic Oedometer
, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed (Supervisor)
Abstract
Laboratory studies to investigate the effects of different saline concentrations (such as sodium chloride or calcium chloride) on the soil water retention behavior of clayey soils and their volumetric changes have received much attention recently. However, many previous studies have investigated these effects in only one path of the SWRC (wetting or drying path) and the effects of saline concentration on hydraulic hysteresis have not been considered. In addition, researchers have frequently studied these effects on SWRC on clay samples, and little research has been done on collapsible soils. Therefore, the most important purpose of this study is to investigate the effects of increasing...
Thermal-hydraulic Analysis of Dry Storage Cask of the Spent Nuclear Fuel and Construction of a Prototype Experimental Setup for its Simulation
, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohammad (Supervisor) ; Mousavian, Khalil (Supervisor) ; Rezaeian, Mahdi (Co-Supervisor)
Abstract
Storage of the spent nuclear fuels is one of the topics of interest in recent years and many researches have been conducted in this field in order to design storage casks for spent nuclear fuels. In this study, thermal-hydraulic analysis of a dry storage cask for Bushehr Nuclear Power Plant spent nuclear fuels is carried out. Geometry of the analyzed cask is taken from a Russian transportation cask TK-13. Drawing of the geometry is achieved with SolidWorks and it’s meshing is completed in Gambit. 3 different cases were considered for cask’s geometry and design: cask without spacers inside, cask with spacers inside, and cask with spacers inside and fins on the outside surface of the cask....
Determination of Strain Dependent Dynamic Parameters of Unsaturated a Silty Soil During Drying path using Resonant Column-Torsional Shear Device
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
Shear modulus and damping ratio are the most important parameters for evaluating the performance of geotechnical systems under seismic and dynamic loads. According to the definition, secant shear modulus is the slope of the hysteresis shear stress-shear strain loop and damping ratio indicates the dissipation of wave energy during propagation in the soil. These parameters depend on stress state, shear strain and void ratio of the soil. Shear strain amplitude has an important effect on the behavior of shear modulus and damping ratio and it is necessary to study the behavior of these parameters in the range of small to large strains. In addition to dynamic loading, climate change and wet and...
Fabrication and Characterization of Nickel-Cobalt Catalyst by One-pot Combustion Synthesis Method for Synthesis Gas Production in Dry Reforming Methane Process
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
Dry reforming methane is a process during which two greenhouse gases, CH4 and CO2, using Ni-based catalysts, are altered into valuable H2 and CO gases, which are very useful from an economic and environmental point of view. The main problem with Ni-based catalysts is the formation of carbon in the dry methane reforming, which leads to rapid deactivation of the catalyst. In this research, a 10Ni-5Co/Al2O3 bimetallic catalyst was prepared by one-pot microwave-assisted combustion synthesis with a stoichiometric amount of fuel (urea) and without the use of additives. The catalyst was then calcined for 12 h at 550oC. The structure, chemical composition, particle distribution, and morphology of...