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    An Online Portfolio Selection Algorithm Using Pattern-matching Principle

    , M.Sc. Thesis Sharif University of Technology Azin, Pejman (Author) ; Khedmati, Majid (Supervisor)
    Abstract
    According to the rise of turnover and pace of trading, accelerating of analysis and making decision is unavoidable. Humans are unable to analyze big data quickly without behavioral biases so, using machines to analyze big data seems critical. Hence, financial markets tend to apply algorithmic trading in which some techniques like data mining and machine learning are notable. OLPS which sequentially allocates capital among a set of assets aiming to maximize the final return of investment in the long run, is the core problem in algorithmic trading. This article presents an online portfolio selection algorithm. The online portfolio selection sequentially selects a portfolio over a set of assets... 

    Taxing Auto Ownership and Use for Reduction of Urban Air Pollution

    , M.Sc. Thesis Sharif University of Technology Azin, Bahar (Author) ; Poorzahedy, Hossein (Supervisor)
    Abstract
    The purpose of this study is to model the long-term effects of taxes on different aspects of private cars upon auto ownership and use, and thereby auto industries in producing more fit cars, so as to minimize auto emission. It involves used car market, different car demands and auto industry production. The study follows some previous studies in this area and tries to enhance the various aspects of the model by directing it toward a more real situation. In order to visualize the effects of the model, it has been applied on the case of Shiraz in 1378. It has been shown that the model was able to reduce air pollution and fuel consumption by 90% and 50%, respectively, as compared to the “Do... 

    An 8-bit current-mode folding ADC with optimized active averaging network

    , Article Scientia Iranica ; Volume 15, Issue 2 , 2008 , Pages 151-159 ; 10263098 (ISSN) Azin, M ; Sharif Bakhtiar, M ; Sharif University of Technology
    Sharif University of Technology  2008
    Abstract
    In this paper, an 8-bit CMOS current-mode folding-interpolating ADC is presented. A new active averaging-interpolating network is described, which results in a better error correction factor compared to its resistive counterpart. Using novel circuits for fast settling and careful transistor sizing, a fast (>160 Msps) and low power (70 mW in 2.5 V supply voltage) 8-bit ADC, with a total chip area of 1 × 1.4 mm in a 0.25 micron CMOS process, is demonstrated. © Sharif University of Technology, April 2008  

    The prediction of the density of undersaturated crude oil using multilayer feed-forward back-propagation perceptron

    , Article Petroleum Science and Technology ; Volume 30, Issue 1 , 2011 , Pages 89-99 ; 10916466 (ISSN) Rostami, H ; Shahkarami, A ; Azin, R ; Sharif University of Technology
    2011
    Abstract
    Crude oil density is an important thermodynamic property in simulation processes and design of equipment. Using laboratory methods to measure crude oil density is costly and time consuming; thus, predicting the density of crude oil using modeling is cost-effective. In this article, we develop a neural network-based model to predict the density of undersaturated crude oil. We compare our results with previous works and show that our method outperforms them  

    An 8-bit 160 MS/s folding-interpolating adc with optimizied active averaging/interpolating network

    , Article IEEE International Symposium on Circuits and Systems 2005, ISCAS 2005, Kobe, 23 May 2005 through 26 May 2005 ; 2005 , Pages 6150-6153 ; 02714310 (ISSN) Azin, M ; Movahedian, H ; Bakhtiar, M. S ; Sharif University of Technology
    2005
    Abstract
    An 8-bit CMOS folding-interpolating analog-todigital converter is presented. A new method for designing optimized averaging circuit is also described. Careful circuit design and layout leads to a high-speed (160 MSPS) and low power (70 mW in 2.5 V supply voltage) ADC. The ADC is successfully implemented in 0.25um CMOS digital process and it takes 1x1.4 mm2 silicon area. © 2005 IEEE  

    Study of the VAPEX process in fractured physical systems using different solvent mixtures

    , Article Oil and Gas Science and Technology ; Volume 63, Issue 2 , 2008 , Pages 219-227 ; 12944475 (ISSN) Azin, R ; Kharrat, R ; Vossoughi, S ; Ghotbi, C ; Sharif University of Technology
    2008
    Abstract
    In this work, the vapour extraction (VAPEX) process is studied experimentally in a rectangular physical model at moderate-high pressure. The solvent was either pure propane or a mixture of propane/ methane with different compositions. The solvent and carrier gas were totally mixed before injection, so that a solvent with the desired composition flowed through the injector during experiments, and the solvent mixture was in thermodynamic equilibrium before injection into VAPEX cell. Effects of pressure and composition of solvent were studied. Results showed that at a fixed pressure, the process is more effective with pure solvent compared to the use of solvent mixtures. The main feature of... 

    Effect of fracture spacing on VAPEX performance in heavy oil fracture systems

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 27, Issue 1 , 2008 , Pages 35-45 ; 10219986 (ISSN) Azin, R ; Kharrat, R ; Ghotbi, C ; Vossoughi, S ; Sharif University of Technology
    2008
    Abstract
    The vapor extraction (VAPEX) process; a solvent-based enhanced oil recovery process has been found promising for some heavy oil reservoirs. In this work, the VAPEX process is studied using a compositional simulator on a number of single-block and multiple block fractured systems. PVT data of one of an Iranian heavy oil reservoir are used to tune the equation of state. Effects of fracture spacing on the performance of process were studied. It was found that the fracture network enhances the VAPEX process in low-permeability systems by increasing the contact area between solvent and oil contained in the matrix blocks. Also, the fracture network reduced the instabilities in the system pressure... 

    Modeling and Simulation of Non-Darcy Gas Flow During Underground Gas Storage in One of Iranian Reservoirs

    , M.Sc. Thesis Sharif University of Technology Dehghan, Hamzeh (Author) ; Taghikhani, Vahid (Supervisor) ; Azin, Reza (Supervisor)
    Abstract
    The Darcy’ law is valid for low velocity or low Reynolds number where merely viscous force is responsible for pressure loss in the porous media. At higher velocity, because of inertial forces and turbulency, the pressure loss would be higher than Darcy’ law estimates; therefore at these flow regimes the Darcy’ law is no longer valid. Hence, consideration of Non-Darcy flow effect is necessary to sufficiently model high gas velocity effects. The velocity is high in gas reservoirs especially those ones that are considered for underground gas storage. In this study, the effects of Non-Darcy flow on several parameters such as; estimation of differential pressure, flowing bottom hole pressure,... 

    The corresponding-states correlation for the prediction of crude Oil undersaturated densities

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 33, Issue 18 , Jul , 2011 , Pages 1739-1746 ; 15567036 (ISSN) Azin, R ; Eslami, H ; Shah Karami, A. R ; Keshavarz, G ; Sharif University of Technology
    2011
    Abstract
    In this work, a corresponding-states correlation is presented for prediction of crude oil density in an undersaturated state. The correlation is the extension of corresponding-states liquid densities correlation. The modified corresponding states liquid densities method for predicting saturated liquid densities was coupled with the Tait equation to predict undersaturated densities. Correlations are proposed for the temperature-dependence of Tait equation parameters. Applying proper mixing and combining rules, we calculated the density of 26 crude-oil samples, mainly from Iranian reservoirs. The mixtures included a variety of compositions including N2, H 2S, CO2, and hydrocarbons. The AAD%... 

    Automatic Blank Verse Poet Identification Using Linguistic Features

    , M.Sc. Thesis Sharif University of Technology Azin, Zahra (Author) ; Bahrani, Mohammad (Supervisor) ; Khosravi Zadeh, Parvaneh (Co-Advisor)
    Abstract
    Author identification using statistical methods is a branch of authorship attribution which is one of important problems in natural language processing. Using different statistical methods, an anonymous text is attributed to an author. One of the primary parts of the task is to choose the appropriate stylistic features of the text in order to study the significances of style. These features must be quantitatively studied and could be extracted in lexical level, character level, and syntactic or semantic levels. The next step is text classification in which different machine learning methods such as decision tree, Artificial Neural Networks, Naïve Bayes and other methods could be used.... 

    Parallelized numerical modeling of the interaction of a solid object with immiscible incompressible two-phase fluid flow

    , Article Engineering Computations (Swansea, Wales) ; Volume 34, Issue 3 , 2017 , Pages 709-724 ; 02644401 (ISSN) Ghasemi, A ; Nikbakhti, R ; Ghasemi, A ; Hedayati, F ; Malvandi, A ; Sharif University of Technology
    2017
    Abstract
    Purpose - A numerical method is developed to capture the interaction of solid object with two-phase flow with high density ratios. The current computational tool would be the first step of accurate modeling of wave energy converters in which the immense energy of the ocean can be extracted at low cost. Design/methodology/approach - The full two-dimensional Navier-Stokes equations are discretized on a regular structured grid, and the two-step projection method along with multi-processing (OpenMP) is used to efficiently solve the flow equations. The level set and the immersed boundary methods are used to capture the free surface of a fluid and a solid object, respectively. The full... 

    Oscillating pipe flow: High-resolution simulation of nonlinear mechanisms

    , Article 2006 ASME Joint U.S.- European Fluids Engineering Division Summer Meeting, FEDSM2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 1 SYMPOSIA , 2006 , Pages 1-10 ; 0791847500 (ISBN); 9780791847503 (ISBN) Ghasemi, A ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    Abstract
    A new perspective suitable for understanding the details of nonlinear pumping (formation of traveling shocks) inside a pressurized cavity is constructed in this paper. Full compressible axisymmetric three-dimensional Navier-Stokes equations are used as the starting point to cover all complexities of the problem that exceedingly increase for particular ranges of Mach, Reynolds and Prandtl numbers. Then a very high-order numerical method is introduced to preserve the user-defined order of accuracy for practical simulations. For removal of spurious waves, higher-order compact filters are derived. All equations are marched in time using the classical Runge-Kutta algorithm which is appropriate... 

    An optimized large-stencil approach for capturing near-PI frequencies

    , Article 12th AIAA/CEAS Aeroacoustics Conference, Cambridge, MA, 8 May 2006 through 10 May 2006 ; Volume 5 , 2006 , Pages 3010-3022 ; 1563478099 (ISBN); 9781563478093 (ISBN) Ghasemi, A ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2006
    Abstract
    Large-stencil schemes which their spectral properties are acceptable in the vicinity of ω = π are analyzed for the first time. A machine independent model for evaluating the efficiency of generalized time-marching finite-difference algorithms over periodic domains is developed. This model which is based on operation count reveals that for small values of Total Computational Cost(TCC), the previous low-order small-stencil schemes are more efficient while for moderate TCC, the efficiency of optimized large-stencil schemes abruptly increases. This important result is the motivation for developing optimized large-stencil schemes. The current schemes are successfully implemented in a full... 

    Numerical solution of high-frequency oscillations of a gas column using a modified lax-wendroff scheme

    , Article International Conference on Noise and Vibration Engineering 2006, ISMA 2006, Heverlee, 18 September 2006 through 20 September 2006 ; Volume 4 , 2006 , Pages 2191-2199 Ghasemi, A ; Sharif University of Technology
    Katholieke Universiteit Leuven  2006
    Abstract
    Recently, several high-order accurate methods have been developed for solving nonlinear equations governing in the high-frequency oscillations of a fluid column. If we assume that the value of Reynolds and Prandtl numbers are high enough then it is possible to neglect the effect of Stokes Layer and it has been previously shown that the calculated pressure profile obtained by solving three-dimensional axisymmetric compressible NS (Navier-Stokes) equations is in good agreement with one-dimensional adiabatic model of Ilinskii. For this particular flow which is the typical of engineering flows inside acoustical compressors, it is clear that high-resolution simulation of NS equations in higher... 

    Oscillating pipe flow: high-resolution simulation of nonlinear mechanisms

    , Article 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2006 , 2006 ; 0791837831 (ISBN); 9780791837832 (ISBN) Ghasemi, A ; Sharif University of Technology
    2006
    Abstract
    A new perspective suitable for understanding the details of nonlinear pumping (formation of traveling shocks) inside a pressurized cavity is constructed in this paper. Full compressible axisymmetric three-dimensional Navier-Stokes equations are used as the starting point to cover all complexities of the problem that exceedingly increase for particular ranges of Mach, Reynolds and Prandtl numbers. Then a very high-order numerical method is introduced to preserve the user-defined order of accuracy for practical simulations. For removal of spurious waves, higher-order compact filters are derived. All equations are marched in time using the classical Runge-Kutta algorithm which is appropriate... 

    Facile synthesis and simulation of MnO2 nanoflakes on vertically aligned carbon nanotubes, as a high-performance electrode for Li-ion battery and supercapacitor

    , Article Electrochimica Acta ; Volume 390 , 2021 ; 00134686 (ISSN) Abdollahi, A ; Abnavi, A ; Ghasemi, F ; Ghasemi, S ; Sanaee, Z ; Mohajerzadeh, S ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    This study reports the successful fabrication of high-performance flexible binder-free lithium-ion battery anode and supercapacitor based on the synthesis of 3D hierarchical MnO2 nanoflakes (NFs) on vertically aligned carbon nanotubes (VACNTs) grown upon stainless steel (SS). The experimental results revealed that the prepared electrodes were well served as supercapacitors with a tremendous specific capacitance of MnO2 NFs VACNT/SS 1131 F/g at 0.25 A/g in 0.5 mol.L−1 Na2SO4, 518.8% more than VACNT/SS (218 F/g). Compared to other MnO2 NFs/CNT composites, as-fabricated binder-free MnO2 NFs/VACNTs electrode achieves outstanding performance with high initial discharge and charge capacities of... 

    Facile synthesis and simulation of MnO2 nanoflakes on vertically aligned carbon nanotubes, as a high-performance electrode for Li-ion battery and supercapacitor

    , Article Electrochimica Acta ; Volume 390 , 2021 ; 00134686 (ISSN) Abdollahi, A ; Abnavi, A ; Ghasemi, F ; Ghasemi, S ; Sanaee, Z ; Mohajerzadeh, S ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    This study reports the successful fabrication of high-performance flexible binder-free lithium-ion battery anode and supercapacitor based on the synthesis of 3D hierarchical MnO2 nanoflakes (NFs) on vertically aligned carbon nanotubes (VACNTs) grown upon stainless steel (SS). The experimental results revealed that the prepared electrodes were well served as supercapacitors with a tremendous specific capacitance of MnO2 NFs VACNT/SS 1131 F/g at 0.25 A/g in 0.5 mol.L−1 Na2SO4, 518.8% more than VACNT/SS (218 F/g). Compared to other MnO2 NFs/CNT composites, as-fabricated binder-free MnO2 NFs/VACNTs electrode achieves outstanding performance with high initial discharge and charge capacities of... 

    Analysis and Modeling of Air Pollution using Big Data Methods in Tehran City

    , M.Sc. Thesis Sharif University of Technology Abrishambaf, Arman (Author) ; Boroushaki, Mehrdad (Supervisor) ; Avami, Akram (Supervisor) ; Nahvijou, Azin (Co-Supervisor)
    Abstract
    Air pollution is a prevalent and pressing issue in Tehran, with significant impacts on both the environment and human health. this study uses statistical techniques, such as Pearson correlation, to determine the direction of influence of meteorological parameters on air pollutant concentrations, and Convergent Cross Mapping to quantify the causal relationship between meteorological parameters and ambient air pollutant concentrations, as well as feedback effects. Additionally, the research delves into the correlation between consumption of fossil fuels and air pollutants, as well as the relationship between lung cancer incidence and mortality by histological subtype and long-term exposure to... 

    Agent-Based Modeling to Estimate Exposure to Urban Air Pollution from Transportation to Assess Carcinogenic Effect

    , M.Sc. Thesis Sharif University of Technology Doraki, Mohammad Erfan (Author) ; Avami, Akram (Supervisor) ; Boroushaki, Mehrdad (Supervisor) ; Nahvijou, Azin (Co-Supervisor)
    Abstract
    Air pollution in major cities has been a concern for over half a century, but its impact on public health has grown significantly in recent years, causing severe physical, mental, and financial harm. This project aims to propose effective policies to mitigate air pollution by focusing on the transportation sector. Transportation demand is analyzed through four scenarios, each addressing changes in public transportation usage, the promotion of cycling and walking culture, the penetration of digital solutions, and flexible working hours. The project, using the Huvaal model, forecasts transportation demand in 2050 under various population and climate conditions, based on artificial population... 

    Equipment failure rate in electric power distribution networks: An overview of concepts, estimation, and modeling methods

    , Article Engineering Failure Analysis ; Volume 145 , 2023 ; 13506307 (ISSN) Ghasemi, H ; Shahrabi Farahani, E ; Fotuhi Firuzabad, M ; Dehghanian, P ; Ghasemi, A ; Wang, F ; Sharif University of Technology
    Elsevier Ltd  2023
    Abstract
    The evolution of the organizational attitudes regarding strategic management of system physical assets and the emergence of new technologies call for special attention to maintenance and reliability. State-of-the-art literature suggested a number of techniques and strategies for estimating the equipment failure rates; however, paralyzed by lack of real-world data, existing literature mostly relied on simplifications that may bring about unique challenges and result in low-accuracy estimations. This paper reviews the existing literature in estimating and modeling the failure rate of power system equipment. The review includes the existing models and the ongoing research on degradation,...