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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) ; 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
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) ; 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) ; 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...
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) ; 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%...
An Online Portfolio Selection Algorithm Using Pattern-matching Principle
, M.Sc. Thesis Sharif University of Technology ; 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 ; 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) ; 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
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) ; 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
Modeling and Simulation of Non-Darcy Gas Flow During Underground Gas Storage in One of Iranian Reservoirs
, M.Sc. Thesis Sharif University of Technology ; 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,...
Automatic Blank Verse Poet Identification Using Linguistic Features
, M.Sc. Thesis Sharif University of Technology ; 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....
Analysis and Modeling of Air Pollution using Big Data Methods in Tehran City
, M.Sc. Thesis Sharif University of Technology ; 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 ; 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...
Network vulnerability analysis through vulnerability take-grant model (VTG)
, Article 7th International Conference on Information and Communications Security, ICICS 2005, Beijing, 10 December 2005 through 13 December 2005 ; Volume 3783 LNCS , 2005 , Pages 256-268 ; 03029743 (ISSN); 3540309349 (ISBN); 9783540309345 (ISBN) ; Sadoddin, R ; Jalili, R ; Zakeri, R ; Omidian, A. R ; Sharif University of Technology
2005
Abstract
Modeling and analysis of information system vulnerabilities helps us to predict possible attacks to networks using the network configuration and vulnerabilities information. As a fact, exploiting most of vulnerabilities result in access rights alteration. In this paper, we propose a new vulnerability analysis method based on the Take-Grant protection model. We extend the initial Take-Grant model to address the notion of vulnerabilities and introduce the vulnerabilities rewriting rules to specify how the protection state of the system can be changed by exploiting vulnerabilities. Our analysis is based on a bounded polynomial algorithm, which generates the closure of the Take-Grant graph...
Sequence dependence of the binding energy in chaperone-driven polymer translocation through a nanopore
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 1 , January , 2011 ; 15393755 (ISSN) ; Ejtehadi, M. R ; Metzler, R ; Sharif University of Technology
2011
Abstract
We study the translocation of stiff polymers through a nanopore, driven by the chemical-potential gradient exerted by binding proteins (chaperones) on the trans side of the pore. Bound chaperones prevent backsliding through the pore and, therefore, partially rectify the polymer passage. We show that the sequence of chain monomers with different binding affinity for the chaperones significantly affects the translocation dynamics. In particular, we investigate the effect of the nearest-neighbor adjacency probability of the two monomer types. Depending on the magnitude of the involved binding energies, the translocation speed may either increase or decrease with the adjacency probability. We...
First passage time distribution of chaperone driven polymer translocation through a nanopore: Homopolymer and heteropolymer cases
, Article Journal of Chemical Physics ; Volume 135, Issue 24 , 2011 ; 00219606 (ISSN) ; Metzler, R ; Ejtehadi, M. R ; Sharif University of Technology
2011
Abstract
Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on...
Reply: Abedpour, asgari, and tabar
, Article Physical Review Letters ; Volume 106, Issue 20 , 2011 ; 00319007 (ISSN) ; Asgari, R ; Tabar, M. R. R ; Sharif University of Technology
2011
Irreversibility in response to forces acting on graphene sheets
, Article Physical Review Letters ; Volume 104, Issue 19 , May , 2010 ; 00319007 (ISSN) ; Asgari, R ; Tabar, M. R. R ; Sharif University of Technology
2010
Abstract
The amount of rippling in graphene sheets is related to the interactions with the substrate or with the suspending structure. Here, we report on an irreversibility in the response to forces that act on suspended graphene sheets. This may explain why one always observes a ripple structure on suspended graphene. We show that a compression-relaxation mechanism produces static ripples on graphene sheets and determine a peculiar temperature Tc, such that for T
Analysis of design goals of cryptography algorithms based on different components
, Article Indonesian Journal of Electrical Engineering and Computer Science ; Volume 23, Issue 1 , 2021 , Pages 540-548 ; 25024752 (ISSN) ; Aref, M. R ; Khorshiddoust, R. R ; Sharif University of Technology
Institute of Advanced Engineering and Science
2021
Abstract
Cryptography algorithms are a fundamental part of a cryptographic system that is designed and implemented to increase information security. They are the center of attention of experts in the information technology domains. Although the cryptography algorithms are implemented to attain the goals such as confidentially, integrity, and authenticity of designing, but other matters that must be noticed by designers include speed, resource consumption, reliability, flexibility, usage type, and so on. For the useful allocation of hardware, software, and human resources, it is important to identify the role of each of the factors influencing the design of cryptographic algorithms to invest in the...
Conservation of statistical results under the reduction of pair-contact interactions to solvation interactions
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 72, Issue 6 , 2005 ; 15393755 (ISSN) ; Farzami, R. R ; Ejtehadi, M. R ; Sharif University of Technology
2005
Abstract
We show that the hydrophobicity of sequences is the leading term in Miyazawa-Jernigan interactions. Being the source of additive (solvation) terms in pair-contact interactions, they were used to reduce the energy parameters while resulting in a clear vector manipulation of energy. The reduced (additive) potential performs considerably successful in predicting the statistical properties of arbitrary structures. The evaluated designabilities of the structures by both models are highly correlated. Suggesting geometrically nondegenerate vectors (structures) as proteinlike structures, the additive model is a powerful tool for protein design. Moreover, a crossing point in the log-linear diagram of...
Multifunctional hyperelastic structured surface for tunable and switchable transparency
, Article Applied Sciences (Switzerland) ; Volume 11, Issue 5 , 2021 , Pages 1-11 ; 20763417 (ISSN) ; Goudarzi, T ; Fleury, R ; Naghdabadi, R ; Sharif University of Technology
MDPI AG
2021
Abstract
We leverage the crucial hyperelastic properties of a multifunctional structured surface to optimize the reconfigurability of the electromagnetic transmission under large nonlinear mechanical deformations. This multiphysics, multifunctional, hyperelastic structured surface (HSS) offers two simultaneous intriguing functionalities; tunability and switchability. It is made of copper reso-nators and a Polydimethylsiloxane (PDMS) substrate, which is one of the most favorable deformable substrates due to its hyperelastic behavior. The proposed HSS is fabricated via an original cost-effective technique and the multiphysics functionalities are captured in both experimental tests and numerical...