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Numerical Simulation of Reacting Flow with Chemical Kinetics using a Modified Dual-Algorithm
, Ph.D. Dissertation Sharif University of Technology ; Darbandi, Masoud (Supervisor) ; Ghafourian, Akbar ($item.subfieldsMap.e)
Abstract
An important issue in aerospace propulsion systems is the reacting flow analyses, which involve many different concepts and physics including various chemical reactions mechanisms and radiation and convection heat transfer physics. As known, the computer simulation is a powerful tool to analyze the reacting flow physics in various combusting environments. It can suitably provide details of both chemical reaction occurrences and heat transfer physics. In combustion environments, the temperature gradient is noticeably affected by the density gradient. On the other hand, the accurate modeling of density gradients highly affects the computational results. In practice, the density-based methods...
Numerical simulation of low-mach-number laminar mixing and reacting flows using a dual-purpose pressure-based algorithm
, Article Numerical Heat Transfer, Part B: Fundamentals ; Volume 59, Issue 6 , Jun , 2011 , Pages 495-514 ; 10407790 (ISSN) ; Darbandi, M ; Hosseinizadeh, S. F ; Sharif University of Technology
2011
Abstract
Benefitting from an analogy between compressible and incompressible governing equations, a novel dual-purpose, pressure-based finite-volume algorithm is suitably extended to simulate laminar mixing and reacting flows in low-Mach-number regimes. In our test cases, the Mach number is as high as 0.00326. Definitely, such low-Mach-number flows cannot be readily solved by either regular density-based solvers or most of their extensions. To examine the accuracy and performance of the extended formulation and algorithm, we simulate two benchmark cases including the mixing natural-convection flow in a square cavity with strong temperature gradients and the premixed reacting flow through annuli with...
Analytical approximate solution of the cooling problem by Adomian decomposition method
, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 14, Issue 2 , 2009 , Pages 462-472 ; 10075704 (ISSN) ; Sedighi, K ; Farhadi, M ; Ebrahimi Kebria, H. R ; Sharif University of Technology
2009
Abstract
The Adomian decomposition method (ADM) can provide analytical approximation or approximated solution to a rather wide class of nonlinear (and stochastic) equations without linearization, perturbation, closure approximation, or discretization methods. In the present work, ADM is employed to solve the momentum and energy equations for laminar boundary layer flow over flat plate at zero incidences with neglecting the frictional heating. A trial and error strategy has been used to obtain the constant coefficient in the approximated solution. ADM provides an analytical solution in the form of an infinite power series. The effect of Adomian polynomial terms is considered and shows that the...
Solution of the falkner-skan equation for wedge by adomian decomposition method
, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 14, Issue 3 , 2009 , Pages 724-733 ; 10075704 (ISSN) ; Farhadi, M ; Sedighi, K ; Ebrahimi Kebria, H. R ; Ghafourian, A ; Sharif University of Technology
2009
Abstract
The Adomian Decomposition Method is employed in the solution of the two dimensional laminar boundary layer of Falkner-Skan equation for wedge. This work aims at the solution of momentum equation in the case of accelerated flow and decelerated flow with separation. The Adomian Decomposition Method is provided an analytical solution in the form of an infinite power series. The effect of Adomian polynomials terms is considered on accuracy of the results. The velocity profiles in boundary layer are obtained. Results show a good accuracy compared to the exact solution. © 2007 Elsevier B.V. All rights reserved
Numerical and Experimental Study of the Partially Premixed Combustion Used in a Compressed Natural Gas Spark-Ignition Direct-Injection Engine
, Ph.D. Dissertation Sharif University of Technology ; Kazemzadeh Hannani, Siamak (Supervisor) ; Ebrahimi, Reza (Supervisor) ; Metghalchi, Hamid (Co-Advisor)
Abstract
Direct injection spark ignition lean burn engine with stratified mixture is concerned recently and research and development are in its initial stage. In this thesis, at first a thermodynamic simulation of these engines was done for investigating of stratified mixture effects on combustion characterization and compare it with homogeneous one. In this modeling we use from turbulent flame speed model for mass burning rate analysis, multizone model for exact measuring of temperature distribution, full chemical kinetic model for emission concentrations and some proposed mixture formation for predicting of stratified mixture. The results shown that stratification is caused to improve combustion...
Investigating the Effect of Patent Activities on the Centrality Indices of Scientific Collaboration Network of Faculty Members in Selected Iranian Universities
, M.Sc. Thesis Sharif University of Technology ; Mirnezami, Reza (Supervisor)
Abstract
Scientific collaboration and the resulting outputs have been always of interest to the scientific community. Specifically, drawing and understanding the elements of scientific collaboration network and identifying its determinants are important step in prescribing and implementing policies in various fields and disciplines of science. Focusing on the Iran context, this study examines the scientific collaborations of faculty members in selected Iranian universities (Sharif University of Technology, University of Tehran, Iran University of Science and Technology, Amirkabir University of Technology, Isfahan University of Technology, and Ferdowsi University of Mashhad). We have drawn the...
Investigating Effects of Interphase on Mechanical Properties of Particulate Metal-Matrix Nanocomposites Using Surface Elasticity
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor)
Abstract
Due to ignoring the effect of length scale and neglecting the details at nanosize, classical methods are not sufficiently accurate to determine the properties of nanostructured materials. More reliable results can be obtained, using surface elasticity theory. Lots of analytical, experimental and numerical investigations have been done on the effect of interphase on the mechanical properties of polymer nanocomposites whereas metal matrix nanocomposites are in the first stages of analytical and numerical researches and have attracted so much attention.
The main objective of this research is to investigate the effects of interphase as well as coating, on the mechanical behavior of metal...
The main objective of this research is to investigate the effects of interphase as well as coating, on the mechanical behavior of metal...
Evaluation and Simulation of using Magnetite as Heat Transfer Medium in Direct Solar Absorption Collectors
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
In this study, application of a Magnetic Nanofluid consisting of Magnetite as Nanoparticle and Water as base fluid in DASC systems is investigated. The DASC system is modeled theoretically and behavior of such system is predicted.In this study a comparison between magnetite Nanofluid and some other common Nanofluids is conducted. The study shows that Magnetite Nanofluid has a better performance and efficiency than Water, Al2O3 Nanofluid and SiO2 Nanofluid. Also magnetite Nanofluid and TiO2 Nanofluid function are almost similar.Also effect of external magnetic field on the performance of magnetite Nanofluid is investigated. It is showed that when the magnetic Nanofluid is subjected to an...
Experimental Investigation of Cooling Surfaces with Electrospray Using a Porous Nozzle
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor)
Abstract
Electrospray, as a novel and efficient method in jet production, utilizes a combination of hydrodynamic and electrostatic forces. In electrohydrodynamic systems, by controlling effective parameters, it is possible to achieve a wide range of fluid flow regimes. Among these, the stable cone-jet mode has attracted special attention from researchers due to its stability and controllability characteristics. The unique features of this mode include uniformity in droplet size resulting from jet breakup (which is effective in reducing temperature gradients on hot surfaces), the ability to control fluid flow characteristics through adjustable parameters such as electrical voltage, and spray...
Identification of the Set of Single Nucleotide Variants in Genome Responsible for the Differentiation of Expression of Genes
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor) ; Beigi, Hamid (Supervisor)
Abstract
Single nucleotide polymorphs, There are changes caused by a mutation in a nucleotide in the Dena sequence. Mononucleotide polymorphisms are the most common type of genetic variation. Some of these changes have little or no effect on cells, while others cause significant changes in the expression of cell genes that can lead to disease or resistance to certain diseases. Because of the importance of these changes and their effect on cell function, the relationships between these changes are also important. Over the past decade, thousands of single disease-related mononucleotide polymorphisms have been identified in genome-related studies. Studies in this field have shown that the expression of...
Synthesis & Characterization of Au-HKUST-1 Nanocomposite and Evaluation of Plasmonic Properties of Gold Nanoparticles in this Nanocomposite
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
In the past few years, many research works on the controllable integration of metal nanoparticles and metal-organic frameworks were done, since the obtained composite material shows a synergism effect in catalysis and photocatalysis, drug delivery applications, gas, and energy storage, as well as sensing. For the first time, in this study, we employed template-assisted growth to synthesize Au-HKUST-1 Nanocomposite. XRD analysis entirely confirms that employing this strategy in synthesizing Au-HKUST-1 was wholly successful, and the plasmonic properties of this nanostructure were studied via UV-visible spectroscopy. In the course of synthesis, gold nanoparticles with 70nm diameter were...
Live Layered Video Streaming over Multichannel P2P Networks
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
Nowadays, video streaming over peer-to-peer networks has become an interesting field to deliver video in large scale networks. As multi-channel live video streaming networks increase,distributing video with high quality among channels faces many challenges. The most significant challenges cause from frequent channel churns, unbalanced channel resources, network heterogeneity and diversity of users’ bandwidths. They include: nodes’ unstability, low users participations, large startup and playback delays, low video quality received by users and lack of resources in unpopular channels.In order to solve the above problems, we have proposed several solutions such as: 1- using distribution groups...
Local Community Detection in Social
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
The fast growth of social networks and their wide range of applications have made the anal-ysis of them an interesting field of research. The growth of concern in modeling large social networksand investigation of their structural features leads studies towards community detec-tion in such networks. In recent years, a great amount of effort has been done for introducing community detection algorithms, many of which are based on optimization of a global cri-terion which needs network’s topology. However, because of big size of most of the social networks , accessing their global information tends to be impossible. Hence, local commu-nity detection algorithms have been introduced. In this...
Improving Graph Construction for Semi-supervised Learning in Computer Vision Applications
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
Semi-supervised Learning (SSL) is an extremely useful approach in many applications where unlabeled data can be easily obtained. Graph based methods are among the most studied branches in SSL. Since neighborhood graph is a key component in these methods, we focus on methods of graph construction in this project. Graph construction methods based on Euclidean distance have the common problem of creating shortcut edges. Shortcut edges refer to the edges which connect two nearby points that are far apart on the manifold. Specifically, we show both in theory and practice that using geodesic distance for selecting and weighting edges results in more appropriate neighborhood graphs. We propose an...
Investigating Conformal Vector Field on Riemannian Manifolds
, M.Sc. Thesis Sharif University of Technology ; Fanai, Hamid Reza (Supervisor)
Abstract
At first the killing vector fields will be investigated. Conditions are introduced for the hypersurface of a Riemannian manifold with a killing vector field to be equipped with the same killing vector field. Then 2-killing vector field is studied and its relation with killing vector fields and monotone vector fields is presented. After that conformal vector fields are discussed and conditions are introduced in order that the Riemannian manifold equipped with a conformal vector field, isisometric to n-dimensional sphere with constant curvature. Finally we will present the conditions which conformal vector field is a 2-killing vector field. Then we will present the results in which the...
Network Topology Inference from Incomplete Data
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
During the last decade, there have been a great number of researches on complex networks.Data aggregation is the first step in the analysis of these networks. However, due to the large scale of them, almost never is there complete information about a network’s different aspects. Therefore, analysis of a complex network is usually done based on the incomplete data. Al-though a good sampling approach in a way that the achieved sample is a good representative of the whole network has its own challenges, analysis of incomplete data causes a significant alternation in the estimation results. Consequently, one of the first problems emerging after sampling is the possibility of predicting the...
Continuous Time Modeling of Marked Events
, Ph.D. Dissertation Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
A great deal of information are continuously generated by users in different contexts such as social networks and online service providers in terms of temporal marked events. These events indicate that what happened to who by when and where.Modeling such events and predicting future ones has interesting applications in different domains such as item recommendation in online service providers and trending topic prediction in online social networks. However, complex longitudinal dependencies among such events makes the prediction task challenging. Moreover, nonstationarity of generative model of events and large size of events, makes the modeling and learning the models challenging.In this...
Analysis and Modeling of User Behavior over Social Media
, Ph.D. Dissertation Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
Nowadays many of us spend a big part of our daily times on social media.One of the most important research problems in social media analysis is how to engage users. The trace of user activity over these websites is a valuable resource for user understanding and engagement, but this data is very huge and unstructured. An approach to deal with this problem is user behavior modeling. In this process, first a behavioral model is considered for users, then using the activity data and the behavioral model, some parameters are learned. Finally, using the learned parameters, a user profile is constructed for each user. This profile can be used for user engagement and many other applications....
Nonlinear Modelling of Return and Volatility in IRANs Auto Industry
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Hadad, Golam Reza (Supervisor)
Abstract
Long memory in assets return is important on the theoretical as well as the practical aspects and since it is a special form of nonlinear dynamics, in this study an ARFIMA model was used with the aim of considering the long memory in the return conditional average of automobile industry index. Then, due to the observation of ARCH effects, the simultaneous conditional average modeling and turbulences in the automotive industry index return using an ARFIMA-FIGARCH model was considered in the residuals of the best fitted model and results were that for modeling the returns and turbulences of automobile industry stocks which has a special long memory, FIGARCH will provide better and more...
Enhancing Branch Target Buffer Efficiency with a Bias-Aware (Re)placement Policy
, M.Sc. Thesis Sharif University of Technology ; Sarbazi Azad, Hamid (Supervisor) ; Hessabi, Shaahin (Supervisor)
Abstract
Branch Target Buffer is a widely used component in modern processors. While there are different designs for BTB, they generally have a set-associative structure keeping branches and their target to help the frontend fetch the instructions on the correct path. To achieve high performance, it’s essential to obtain a high hit rate out of the BTB. Prior works has shown that BTB suffers from frequent misses that require large sizes or sophisticated BTB prefilling mechanisms to overcome the problem. However, the first solution imposes a significant storage overhead, and the latter results in limited benefits. Prior works have shown that branches exhibit different behaviors from being strongly...