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salari--meysam
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The Course of Martin Heidegger’s Notion of Science in His Early Thought,Based on Works Preceding Being and Time
, M.Sc. Thesis Sharif University of Technology ; Sefidkhosh, Meysam (Supervisor)
Abstract
In this research, first of all, the main question of Heidegger and his epoch is investigated. If we read Heidegger along the tradition of German philosophy, then it is perceived that the problem of science is the most central subject matter standing against Heidegger. My question is this: how Heidegger reaches to this existential phenomenological view about science. Regarding that, by giving a coherent narration about a crucial problem called 'the crisis of science', in the first chapter I gave a short view to philosophies preceding Heidegger, some important of which is Dilthey's philosophy of life, phenomenology of Husserl, and south-west school of neo-Kantianism. The second chapter...
An ACO algorithm for the graph coloring problem [electronic resource]
, Article Computational Intelligence Methods and Applications, ICSC Congress on ; 2005 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
Ant colony optimization (ACO) is a well-known metaheuristic in which a colony of artificial ants cooperate in exploring good solutions to a combinatorial optimization problem. In this paper, an ACO algorithm is presented for the graph coloring problem. This ACO algorithm conforms to max-min ant system structure and exploits a local search heuristic to improve its performance. Experimental results on DIMACS test instances show improvements over existing ACO algorithms of the graph coloring problem
Explaining Moral Role of Artifacts With Regards to Value Laden Theory of Technology
, M.Sc. Thesis Sharif University of Technology ; Sefidkhosh, Meysam (Supervisor) ; Taghavi, Mostafa (Supervisor)
Abstract
In this thesis we review different approaches to the theory of value laden technology and realize that there are at least two major ideas about this. Some philosophers believe that technology is not a mere instrument and has a value laden nature. In contrast some others count technology as something neutral which contains no social or moral value. After explaining this ideas, in the second chapter we examine different models which explain the relation between technology and moral and social values and show how this values can contribute in design and use of technologies. In chapter three we talk about different methods used to steer technology in a desirable way which is in accordance with...
On the Topological Entropy of Geodesic Flows
, M.Sc. Thesis Sharif University of Technology ; Razvan, Mohammad Reza (Supervisor) ; Nassiri, Meysam (Supervisor)
Abstract
Let M be a connected, compact, Riemannian manifold. Geodesic flow is a flow on the unit tangent bundle of M . This flow can be studied in dynamics prespective. for example entropy or complexity of the geodesic flow. in this thesis we will follow methods of entropy estimation or computing for geodesic flow. we will follow the method of anthony manning and Ricardo Mañe for proving such result. Maning present two results linking the topological entropy of the geodesic flow on M. we expalin how he find exponential growth rate volume of balls in universal cover as a lower bound for topologycal entropy. another theorem , Mañe represent the equlity between exponential growth rate of avrage of...
Classification of Partial Hyperbolic Diffeomorphisms on 3-manifolds
, M.Sc. Thesis Sharif University of Technology ; Safdari, Mohammad (Supervisor) ; Nassiri, Meysam (Supervisor)
Abstract
In this dissertation, we will study partially hyperbolic diffeomorphisms. First, we are going to introduce partially hyperbolic diffeomorphisms and construct some examples. One of the important questions in the study of partially hyperbolic diffeomorphisms is their classification problem, which provides a deeper understanding of manifolds and also of partially hyperbolic diffeomorphisms themselves. We will go through this problem by examining Hammerlindl, Potrie’s [1]’s work. They have proved that a partially hyperbolic diffeomorphism on a 3-manifold with a virtually solvable fundamental group, that has no periodic torus tangent to contraction-center or expansion-center, is dynamically...
Experimental Study of Microbubbles Generation as a Contrast Agent in Blood, to Determine the Blood Flow by Echo-PIV Method
, M.Sc. Thesis Sharif University of Technology ; Shafiee, Behshad (Supervisor)
Abstract
Today microbubbles are broadly used as ultrasound contrast agents. These bubbles enhance the image resolution of B-mode pictures. Flow focusing in microchannels could provide us the goal of one-size bubbles generation. Microbubbles could use as tracers in Echo_PIV method to determine the velocity profile in main body vessels such as carotid. In this paper we introduce a new production method to fabricate a low-cost microchannel for preparing Microbubble contrast agents (less than 50 microns) by using some surface active agents and a viscosity enhancing material to obtain appropriate Microbubbles with desired life time and stability for any in vitro infusion for velocity measurement. By...
, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan (Supervisor)
Abstract
Centrifugal Fans are widely used in industrial and commercial applications, from shop ventilation to material handling to boiler applications. They consume extremely high amount of energy each year. Because of this high consumption, even a small efficiency improvement could led to high amount of energy saving. Many projects have been done with this goal up to now, and present work is one of them, with aim to optimize a industrial centrifugal BI fan performance, with wheel diameter about 400 mm. The research has been done based on 3D numerical methods, done by commercial code Fluent 6.3, in steady state. MRF and k-E models have been used to simulate flow around blades, and turbulence...
A Risk based Project value Model to Obtain the Optimum Value of Activities’ Costs
, M.Sc. Thesis Sharif University of Technology ; Kianfar, Farhad (Supervisor)
Abstract
In the proposed model, it is attempted to obtain the optimum cost of activities concerning their relevant risks. I n doing so, the concept of risk based project value (RPV) has been employed to measure the expected earn of each individual activity in the presence of risks. Generally, in the model, the risks are divided into critical and non-critical risks. Critical risks cause termination of activities and non-critical risks that are not as severe as critical risks and lead to monetary lost. In the next step, the risk response plans are utilized to reduce the possible adverse effects of risks. These plans, also known as action plans, are the preventive or adaptive actions that aim to reduce...
Studying the Effects of Sintering Parameters on the Microstructure and Properties of Porous Polymeric Products
, M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza (Supervisor)
Abstract
Nowadays filtration process is increasingly used in various areas such as water purification, food industries, filtering the air dust and other separation applications. In this work, the HDPE microporous filters have been fabricated at different temperature, pressure and time conditions via sintering process and then were characterized by different techniques. It can be expected that microstructure and mechanical properties of the samples could be controlled by changing the fabrication parameters of the process and also by changing the properties of the resin such as powder shape, particle size and rheological properties. In the first step, by using DSC, MFI, rheology test and optical...
Fabrication of sintered porous polymeric materials: effect of chain interdiffusion time on mechanical properties
, Article Polymer International ; Volume 67, Issue 4 , 2018 , Pages 422-430 ; 09598103 (ISSN) ; Pircheraghi, G ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
In this study, sintered porous polymeric materials made of high density polyethylene (HDPE) were fabricated through controlling the chain interdiffusion time at the transition temperature of semicrystalline and melt states. At this intermediate state, where both crystalline and amorphous phases coexist, the interfacial welding of HDPE particles is facilitated thanks to interdiffusion caused by chain relaxation phenomena. Then, by assuming a spherical shape and a cubic packing configuration of particles, a geometrical model was developed to predict porosity variations as sintering progresses. Moreover, the HDPE used, as a broad molecular weight distributed polymer, has different family chains...
Interdiffusion versus crystallization at semicrystalline interfaces of sintered porous materials
, Article Polymer ; Volume 156 , 2018 , Pages 54-65 ; 00323861 (ISSN) ; Pircheraghi, G ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Sintering process at temperature intervals close to the melting point of polymers is greatly important due to its role in synthesizing porous materials. During sintering, particles of polymeric materials coalesce throughout a process called interdiffusion. On the contrary, crystallization strongly affects the interdiffusion process at temperature intervals below and close to the melting point. Apparently, the outcome of the contention between these two factors would determine the interfacial width. Therefore, the current study presents a model, which takes both crystallization and interdiffusion into account, to predict sintering kinetic. Consequently, interfacial strength was assessed with...
Facile template-free synthesis of new α-MnO2 nanorod/silver iodide p-n junction nanocomposites with high photocatalytic performance
, Article New Journal of Chemistry ; Volume 44, Issue 18 , 2020 , Pages 7401-7411 ; Kohantorabi, M ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
In the present study, a novel α-MnO2/AgI photocatalyst was successfully fabricated by using hydrothermal/precipitation methods, and its photocatalytic performance was evaluated from the degradation of Acid blue 92 (AB92) dye under visible light irradiation. The surface and crystalline structure, morphology, and electro-chemical properties of the as-made photocatalyst were investigated by BET, XRD, XPS, SEM-EDS, TEM, DRS, PL, PC, and Raman analysis. The optimized nanocomposite (α-MnO2/AgI) with a weight ratio of 1:15 showed the best photocatalytic activity in the decomposition of AB92 with a removal efficiency of 100% in 40 min which was better than that of pure α-MnO2 (48%) and AgI (61%),...
Fabrication of novel Fe2O3/MoO3/AgBr nanocomposites with enhanced photocatalytic activity under visible light irradiation for organic pollutant degradation
, Article Advanced Powder Technology ; Volume 31, Issue 1 , 2020 , Pages 493-503 ; Kohantorabi, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In the present work, the novel ternary Fe2O3/MoO3/AgBr photocatalyst with different dosages of AgBr was successfully synthesized via a facile method. The physicochemical properties of the resultant catalyst were characterized by using various techniques such as XRD, SEM, EDX, BET, XPS, DRS, and VSM. The photocatalytic performance of as-prepared samples was evaluated by degradation of organic dye acid blue 92 (AB92) under visible light irradiation, and in dark. The impact of different operating parameters namely calcination temperature, amount of photocatalyst, dye concentration, and pH of solution were investigated in degradation reaction. Ternary nanocomposite exhibited the best...
Effect of microstructural inhomogeneities on texture evolution in 90-10 Brass sheets
, Article Journal of Materials Processing Technology ; Volume 182, Issue 1-3 , 2007 , Pages 440-444 ; 09240136 (ISSN) ; Akbarzadeh, A ; Sharif University of Technology
2007
Abstract
The control of texture and microstructure can be achieved by an appropriate thermomechanical treatment in industrial production. The effects of finish rolling temperature, cold reduction and annealing temperature on texture development and microstructure in Brass sheet were investigated. The role of deformation inhomogeneities on texture evolution has been considered. The formation of transition bands during hot rolling enforced the intensity of cube components. Shear bands increased the intensities of S and Cu components after cold rolling and at higher cold reductions. Transition from Cu to Y and Y to Bs was completed better because of mechanical twinning. Thermal twins annihilated the...
Heterogeneous photocatalytic degradation of organic pollutant in aqueous solutions by S-scheme heterojunction in nickel molybdate nanocomposites
, Article Journal of Environmental Chemical Engineering ; Volume 9, Issue 5 , 2021 ; 22133437 (ISSN) ; Kohantorabi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A novel ɑ-NiMoO4/ɑ-MoO3 binary nanocomposite was fabricated by using facile method. The fabricated nanocomposite was characterized by various techniques, and the photocatalytic activity was evaluated in degradation of Acid blue 92 dye. Among of as-made photocatalysts with various weight ratios of ɑ-MoO3, ɑ-NiMoO4/ɑ-MoO3 (1:5%w/w) exhibited the best photocatalytic performance, and selected as optimum photocatalyst. Under optimum reaction conditions ([dye] = 10 mg L−1, [catalyst] = 200 mg L−1, and pH = 7.0), complete removal efficiency was obtained within 100 min. Also, the first-order rate constant value of reaction in the presence of ɑ-NiMoO4/ɑ-MoO3 was calculated to be 0.032 min−1 that was...
An ACO algorithm for graph coloring problem
, Article 2005 ICSC Congress on Computational Intelligence Methods and Applications, Istanbul, 15 December 2005 through 17 December 2005 ; Volume 2005 , 2005 ; 1424400201 (ISBN); 9781424400201 (ISBN) ; Eshghi, K ; Sharif University of Technology
2005
Abstract
Ant Colony Optimization (ACO) is a well-known metaheuristic in which a colony of artificial ants cooperate in exploring good solutions to a combinatorial optimization problem. In this paper, an ACO algorithm is presented for the graph coloring problem. This ACO algorithm conforms to Max-Min Ant System structure and exploits a local search heuristic to improve its performance. Experimental results on DIMACS test instances show improvements over existing ACO algorithms of the graph coloring problem
Fault Detection of Offshore Wind Turbines Using Data Driven Methods
, M.Sc. Thesis Sharif University of Technology ; Sadati, Nasser (Supervisor)
Abstract
Technology systems are vulnerable to various defects. Acuator failures reduce the performance of control systems and even they can damage the entire system. Incorrect reading from the sensors is the cause of many inefficiencies, because errors can reduce the quality and efficiency of a product line. In addition, failure of a single system's component can cause a system failure. Electromechanical energy conversion devices are composed of hundreds different components and subunits that are subject to varying adverse environmental conditions, and that is why the sensors, actuators, and components are likely to malfunction. Unexpected defects and unplanned repairs result in high operating costs...
Strictly Toral Dynamics
, M.Sc. Thesis Sharif University of Technology ; Esfahanizadeh, Mostafa (Supervisor) ; Nassiri, Meysam (Supervisor)
Abstract
This dissertation deals with nonwandering (e.g. area-preserving) homeomorphisms of the torus which are homotopic to the identity and strictly toral, in the sense that they exhibit dynamical properties that are not present in homeomorphisms of the annulus or the plane. This includes all homeomorphisms which have a rotation set with nonempty interior. There are two types of points: inessential and essential. It is known that the set of inessential points Ine(f ) is a disjoint union of periodic topological disks ("elliptic islands"), while the set of essential points Ess(f ) is an essential continuum, with typically rich dynamics ("the chaotic region"). One of the key results in this context is...
A numerical study of dust deposition effects on photovoltaic modules and photovoltaic-thermal systems
, Article Renewable Energy ; Volume 135 , 2019 , Pages 437-449 ; 09601481 (ISSN) ; Hakkaki Fard, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Dust deposition on the surface of solar systems is one of the main parameters that significantly affects the performance of such systems. In this study, the effect of dust deposition density on the performance of photovoltaic modules (PV) and photovoltaic-thermal systems (PVT) is numerically investigated. Accordingly, all layers of a monocrystalline silicon PV module for both systems are simulated. Moreover, the effect of various system parameters on the performance of both clean and dusty PV module and PVT system are studied. The studied parameters included: solar radiation intensity, ambient temperature, coolant inlet temperature, and coolant inlet velocity. The obtained results indicate...
Thermodynamic analysis of a photovoltaic thermal system coupled with an organic Rankine cycle and a proton exchange membrane electrolysis cell
, Article International Journal of Hydrogen Energy ; Volume 47, Issue 41 , 2022 , Pages 17894-17913 ; 03603199 (ISSN) ; Hakkaki Fard, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this study, the performance of a Photovoltaic Thermal-Organic Rankine Cycle (PVT-ORC) system combined with a Proton Exchange Membrane Electrolysis Cell (PEMEC) is investigated. A combined numerical/theoretical model of the system is developed and used to evaluate the effect of various system design parameters. In addition, the effects of using water, ethylene glycol, and a mixture of water and ethylene glycol (50/50) as the working fluid of the PVT system and R134a, R410a, and R407c as the working fluid of the ORC cycle on the performance of the PVT-ORC-PEMEC system are studied. Based on the results, R134a and water demonstrated the best performance as the working fluid of the ORC and PVT...