Electrophoretic Deposition of Ni/SiO2 Nanocomposite Coating: Fabrication Process and Tribological and Corrosion Properties

, M.Sc. Thesis Sharif University of Technology Ghalayani Isfahani, Arash (Author) ; Ghorbani, Mohammad (Supervisor)

Abstract

Ni/SiO2 nanoparticle composite coatings were prepared by electrophoretic deposition (EPD) and their hardness, wear and corrosion resistance were examined. Additionally, the morphology of the coatings was observed. In the first phase, the feasibility of coating with Scanning Electron Microscopy (SEM) as well as X-ray diffraction (XRD) and Energy Dispersive Spectra (EDS) techniques was evaluated. After finding the effect of concentration of nanoparticles on coating characteristics and the results of using SEM, optimum conditions for uniform coating, acceptable adhesion at 20V and concentrations of 10 g/L for Ni, 1.2 g/L for SiO2, and choosing NiCl2 as additive with a concentration of 0.2 g/L...

Hegel's ontology of power : the structure of social domination in capitalism

, Book Abazari, Arash

Cambridge University Press 2020

Electrophoretic deposition of Ni/SiO2 nanocomposite coating: Fabrication process and tribological and corrosion properties

, Article Journal of Nano Research ; Volume 26 , 6 January , 2014 , Pages 45-51 ; ISSN: 16625250 Isfahani, A. G ; Ghorbani, M ; Sharif University of Technology

2014

Abstract

To the best of our knowledge, this work presents the first successful effort to fabricate and study nanostructured Ni-based composite coatings using the electrophoretic deposition method with nanostructured SiO2 particles. In this work, Ni/SiO2 nanoparticle composite coatings were prepared by electrophoretic deposition (EPD) [1] and their hardness, wear and corrosion resistances [2] were examined. After studying the morphology of the coatings and finding the optimum conditions for uniform coating, in order to improve the mechanical properties as well as resistance to corrosion, sintering was performed. The Ni/SiO2 nanocomposite coatings show excellent hardness (∼376 HV), reduced Young's...

Flight Frequency Determination and Aircraft Routing Problem: Model and Solution

, M.Sc. Thesis Sharif University of Technology Nasr Isfahani, Hossein (Author) ; Shafahi, Yusof (Supervisor)

Abstract

This study aims to solve weekly Flight Frequency Determination and Aircraft Maintenance Routing Problem (AMRP) simultaneously. The objective function here is to maximize the total net profit of an assumptive airline with predetermined airfare and origin-destination market demand. All the needed constraints regarding AMRP is added to the modified version of original model which proposed by Ghafoori in 2011. On the other hand, while this kind of model is based on travelling salesman problem, the occurrence of sub-tours is inevitable. Thus, the model will be, secondly, restricted with more constraints which help eliminate infeasible solutions. The proposed model, then, is tested for three...

A New Model for Track Maintenance Management System (Case study: Iranian Railway)

, M.Sc. Thesis Sharif University of Technology Share Isfahani, Hajar (Author) ; Shafahi, Yusof (Supervisor)

Abstract

Railway managers have strong economic incentive to minimize the cost of track maintenance in order to conserve safety standards and provide adequate service levels for train operators. The main object of this study is to provide a method for railway repairing and maintaining management and improve previous researchs.
In this study, a cumulative damage model based upon a nonhomogeneous Markov process is developed to model track deterioration. The maintenance of deteriorating facilities can be a great challenge because the process of deteriorating has random features for some facilities.
The genetic algorithm is used to find the optimal repair for each possible track state in the...

Leg Design for Quadrupedal Planetary Explorer Robot

, M.Sc. Thesis Sharif University of Technology Samiei Isfahani, Saman (Author) ; Hadadpour, Hassan (Supervisor)

Abstract

Road casualty is the fifth leading cause of death in Iran. To adopt proper countermeasures there is a need to evaluate the consequences of the implemented policies. Despite the development of crash time series models, these methods have not been in accordance with the multivariate, seasonal, and non-linear nature of crash data. On the other hand, the interpretable crash causal analysis frameworks are descriptive and they lack predictive power. Moreover, the unobserved homogeneity between observations has been widely overlooked in the crash causal analysis literature. This thesis introduces a novel causal analysis methodology by combining the interpretability and prediction power of the...

The most optimal barrier height of InGaN light-emitting diodes

, Article Applied Physics A: Materials Science and Processing ; Volume 127, Issue 2 , 2021 ; 09478396 (ISSN) Alam Varzaneh Isfahani, M. H ; Faez, R ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2021

Abstract

In this paper, a novel structure is presented in order to decrease the polarization charges of quantum wells. The main purpose of this design is to make electron and hole wavefunctions closer to each other and to increase overlap integral following an increase of radiative recombination rates and internal quantum efficiency. Furthermore, carriers will be increased and become more balanced and identical which leads to an increase in efficiency of light-emitting diodes. The improvement of radiative recombination rates is studied in new structures. Energy bands diagram, carriers density, current density–voltage, and power density–current density are used to demonstrate the superior performance...

The most optimal barrier height of InGaN light-emitting diodes

, Article Applied Physics A: Materials Science and Processing ; Volume 127, Issue 2 , 2021 ; 09478396 (ISSN) Alam Varzaneh Isfahani, M. H ; Faez, R ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2021

Abstract

In this paper, a novel structure is presented in order to decrease the polarization charges of quantum wells. The main purpose of this design is to make electron and hole wavefunctions closer to each other and to increase overlap integral following an increase of radiative recombination rates and internal quantum efficiency. Furthermore, carriers will be increased and become more balanced and identical which leads to an increase in efficiency of light-emitting diodes. The improvement of radiative recombination rates is studied in new structures. Energy bands diagram, carriers density, current density–voltage, and power density–current density are used to demonstrate the superior performance...

A new approach for touching cells segmentation

, Article BioMedical Engineering and Informatics: New Development and the Future - 1st International Conference on BioMedical Engineering and Informatics, BMEI 2008, Sanya, Hainan, 27 May 2008 through 30 May 2008 ; Volume 1 , 2008 , Pages 816-820 ; 9780769531182 (ISBN) Nasr Isfahani, S ; Mirsafian, A ; Masoudi Nejad, A ; Sharif University of Technology

2008

Abstract

Automatic cell segmentation has various applications in different parts of science. The development of automated methods for cell segmentation, remains challenging in situations where there are touching cells. In this paper we propose a new method for separating touching cells. As the first step, we use a combination of graph segmentation algorithm and thresholding for segmenting foreground objects and producing a binary image. Next, boundary points of separation zone are selected by using a corner detection algorithm. Finally, the marker controller watershed transform is applied to separate touching cells at selected points. © 2008 IEEE

A more accurate prediction of liquid evaporation flux

, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 23, Issue 2 , 2004 , Pages 45-53 ; 10219986 (ISSN) Khosravi Darani, K ; Sabzyan, H ; Zeini Isfahani, A ; Parsafar, G ; Sharif University of Technology

Iranian Journal of Chemistry and Chemical Engineering 2004

Abstract

In this work, a more accurate prediction of liquid evaporation flux has been achieved. The statistical rate theory approach, which is recently introduced by Ward and Fang and exact estimation of vapor pressure in the layer adjacent to the liquid-vapor interface have been used for prediction of this flux. Firstly, the existence of an equilibrium layer adjacent to the liquid-vapor interface is considered and the vapor pressure in this layer and its thickness calculated. Subsequently, by using the Fick's second law, an appropriate vapor pressure expression for the pressure of equilibrium layer is derived and by this expression and the statistical rate theory approach, evaporation flux is...

Theoretical and Experimental Investigation of Biogas Production Reactor Performance

, Ph.D. Dissertation Sharif University of Technology Ghofrani Isfahani, Parisa (Author) ; Shahrokhi, Mohammad (Supervisor) ; Vossoughi, Manouchehr (Supervisor)

Abstract

Due to the high cost and destructive effects of fossil fuels, the biogas production as a renewable and environmentally friendly fuel attracted much attention. In this regard, several targets are considered in this research. First, in order to increase of biogas production yield and accelerating the rate limiting steps in anaerobic digestion of wheat straw (lignocellulosic feedstock), the effect of additives containing trace elements (Fe and Ni) in form of nanoparticles and their salts was investigated through batch experiments. The results showed that addition of nanoparticles or salts resulted in the increase of methane production rate during the first 4 days of experiments. Then, a...

About Space Time

, M.Sc. Thesis Sharif University of Technology Naderi, Mojtaba (Author) ; Rastegar, Arash (Supervisor)

Abstract

Einstein's general theory of relativity is an admirable successful and unifier geometrical modeling among concepts of space, time and gravity. This theory along with special theory of relativity made a massive change in our physical view and this, especially in its historical context, has deep and interesting consequences in man's philosophical viewpoint which can be studied. Some parts of this thesis relates to these consequences. Some of these interesting consequences may be hidden by computional or mathematical viewpoint and often these equations do not contain enough intuition. in one part, we provide a formulizatin of Einstein's equaion that is intuitional which can be translated in...

Tropical Algebraic Geometry

, M.Sc. Thesis Sharif University of Technology Yaghmayi, Keyvan (Author) ; Rastegar, Arash (Supervisor)

Abstract

Tropical algebraic geometry is a fairly new branch in geometry which is called so in honor of Brazilian mathematician Imre Simon who was pioneer of this field.The set equipped with the addition and multiplication is a semifield.Algebraic geometry objects like algebraic varieties can be defined over.Polynomials and rational functions are defined over.The functions that they define are piecewise linear and concave functions and the set of points where they are nonlinear is a tropical variety which is a concave polyhedral. Thus, tropical algebraic geometry is a piecewise linear version of algebraic geometry.Another approach to tropical algebraic geometry comes back to the works of Russian...

Evaluating the Effect of Crumb Rubber on the Fracture Properties of Asphaltic Materials Using a Standardized Composite

, M.Sc. Thesis Sharif University of Technology Ghanbari, Amir (Author) ; Motamed, Arash (Supervisor)

Abstract

Fatigue cracking has a major impact on the performance of flexible pavements. Many test methods have been established to evaluate and estimate the fatigue life of asphaltic materials. Most of these test methods cannot successfully examine the fatigue properties of asphaltic materials. Recent studies demonstrate that using a standardized composite, which consists of glass beads and asphalt binder, can simulate the stress states that binder experiences in the field. This research used standardized composite to investigate the effect of crumb rubber on the fracture properties of asphaltic materials. To validate the test results, the authors conducted fracture tests on the Fine Aggregate Matrix...

Novel View Synthesis Using Light Field Camera

, M.Sc. Thesis Sharif University of Technology Bemana, Mojtaba (Author) ; Amini, Arash (Supervisor)

Abstract

In the last two decades, novel view synthesis has become increasingly important in the movie and game industries. The new generated views correspond to virtual viewpoints, where no real camera has taken snapshot. Depending on the amount of available information from the scene, different approaches have been proposed to create novel views. If the depth information is available, then by knowing camera relative motion, novel views can be constructed. The conventional cameras only record the intensity of the captured scene, and discard the depth information. In the recent concept of light field cameras, by locating an array of micro-lenses between the camera sensor and the main lens, one can...

Developing a New Method to Evaluate and Quality Control of Chip Seal

, M.Sc. Thesis Sharif University of Technology Jahi, Hamed (Author) ; Motamed, Arash (Supervisor)

Abstract

Chip seal is one of the most economical pavement maintenance practice that extends pavement life. To ensure chip seal good performance several quality control methods have been developed. However, most of these methods are qualitative and only measure the stone loss under a certain number on loading. This research developed a new method for quality control of chip seal, based on the assumption that characteristics of the bond between chips and pavement surface play a key role in chip seal performance. To validate this test method, the authors used a wheel track loading test. The results from this research clearly showed that the characteristics of the bond between chips and pavement surface...

Investigating the Effect of Various Additives on the Curing Time of Chip Seal and Chip Seal Treatments in Different Climate Conditions.

, M.Sc. Thesis Sharif University of Technology Sadeghi, Amir (Author) ; Motamed, Arash (Supervisor)

Abstract

Recently, a new method to investigate chip seal performance has developed by a research team at Sharif University of Technology. This study investigates the effect of various additives such as CRM, SBR Latex, Hydrated Lime and Ordinary Portland Cement (OPC), on the curing time of chip seal by this method. In addition, the chip seal treatments were investigated in different climate conditions like Wet and Wet-Freeze zones. The overall performance of mixture specimens evaluated using creep loading test. In fact, the bonding properties between aggregates and surface of Hot Mix Asphalt measured. The test results were analyzed by using of the work and time parameters. These parameters were...

Brandom’s Conception of Trust

, M.Sc. Thesis Sharif University of Technology Razzaghi, Ashkan (Author) ; Abazari, Arash (Supervisor)

Abstract

A Spirit of Trust results from Brandom's thirty-year effort to give a pragmatistic reading of Hegel's Phenomenology of Spirit. In A Spirit of Trust, Brandom reformulates Hegel's arguments in the language of contemporary Analytical Philosophy and gives a unique interpretation of Hegel's key concepts. In this Thesis, we will examine one of its key concepts, namely, Trust; We will pursue the following questions: First, What is Trust? And what is its connection to other aspects of Brandom's philosophy? Second, How does Trust help us in overcoming Alienation? Third, Are Confession and Forgiveness, which are the constitutive concepts of Trust, psychologistic or normative? Fourth, What is the...

Design of Stress Absorbing Membrane Interlayer (Sami) and Overlay to Reduce Reflective Cracking

, M.Sc. Thesis Sharif University of Technology Taheri, Amir (Author) ; Motamed, Arash (Supervisor)

Abstract

Cracks or construction joints in an overlayed pavement can propagate into the overlay over time due to various factors, the most important of which are traffic and temperature loading, and cause premature failure of pavement. This propagated cracks are called reflective cracks and the phenomenon of crack propagation into the overlay is called reflective cracking. Use of stress-absorbing membrane interlayers (SAMI) is one of the ways can reduce the occurrence of reflective cracking and/or delay it. One of the most common SAMIs is an asphalt mixture consists of bitumen and aggregate layed down between the old and the veneer layers. The function of the SAMI depends on several factors such as...

An Investigation on the Effect of Filler Type and Content on the Performance of Asphaltic Materials

, M.Sc. Thesis Sharif University of Technology Hamidi, Arman (Author) ; Motamed, Arash (Supervisor)

Abstract

The objective of this research is evaluating the effect of filler type and content on the characteristics of asphaltic materials. The properties of the asphalt mixture are greatly influenced by its components. As asphalt mixtures are composed of two prominent components, aggregates and binder, the change in type and contents of these materials may lead to altering the performance of asphalt mixtures. Aggregates in the asphalt mixtures are categorized into three groups based on their particle sizes: coarse aggregate, fine aggregate and mineral filler. The effect of filler on the characteristics of asphalt mixtures can be examined by changing the type and content of filler and holding the...