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Application of population balance equation in modeling of asphaltene particle size distribution and characterization of aggregation mechanisms under miscible gas Injection
, Article Journal of Molecular Liquids ; Volume 232 , 2017 , Pages 207-213 ; 01677322 (ISSN) ; Hamed Mahvelati, E ; Ameli, F ; Dabir, B ; Rashtchian, D ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Particle size distribution (PSD) is an important factor that determines how asphaltene instability can damage porous media during natural depletion and enhanced oil recovery processes. In this work, aggregate size distribution under natural depletion and miscible nitrogen injection processes are determined via image analysis techniques and the results are modelled by population balance equation. Unimodal distribution curves in natural depletion show the dominance of particle-particle aggregation mechanism and the clustering is detected only around crude oil bubble point pressure. It is also observed that miscible nitrogen injection considerably increases the number and size of asphaltene...
Designing an Automated and Smart Electric Power Distribution System
, M.Sc. Thesis Sharif University of Technology ; Vakilian, Mehdi (Supervisor)
Abstract
Feeder reconfiguration is one of the most prominent tasks for loss reduction, reliability improvement and also congestion alleviation in distribution networks. Besides improving abovementioned operational issues, during a long period of time, proper switching in appropriate times can causes a lot of economic savings. Furthermore, it can be intensified when capacitors are implemented and controlled in the network. To reach this purpose, most of the previous literature focuses merely on the power grid reconfiguration. Few of these researches have considered this problem as a dynamic one and studied that in a period of time, e.g. one day, considering fixed level of loads despite the others that...
Proposing a Control Strategy for Treatment of Hepatitis C Disease
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
Due to the importance of hepatitis disease, especially hepatitis C, from public health view point, this research aims to investigate and suggest an efficient medical therapy for this disease. First, available models are analyzed and the suitable one is chosen. Three controllers namely, fixed PI, adaptive PI and exact linearization control (GLC) are designed to control the hepatitis C disease using the drug efficacy as the manipulated variabel. Controller parameters are determined by the Genetic Algorithm (GA) and their performances are evaluated using the selected model. Uncertainties have been considerd in both model structure and parameters and controllers performances are investigated in...
A novel simultaneous reconfiguration and capacitor switching method to improve distribution networks operation
, Article 2014 14th International Conference on Environment and Electrical Engineering, EEEIC 2014 - Conference Proceedings ; May , 2014 , pp. 295-300 ; ISBN: 9781479946617 ; Davari-Nejad, E ; Kamyab, F ; Vakilian, M ; Haghifam, M. R ; Sharif University of Technology
2014
Abstract
Due to the important role that distribution systems play in quality of power delivered to the customers, there has always been a great deal of interest in investigating different methods of efficiency enhancement for these networks. Two of these methods are Feeder Reconfiguration (FR) and Capacitor Allocation (CA); both have been widely employed to reduce losses and improve several other operational characteristics in electrical power distribution systems. As in FR process the topology of the network changes, it is necessary to change some previous settings; for instance: the capacity of capacitor banks in service in each bus, after each reconfiguration process. This is due to the fact that...
Iranian national olympiad in informatics
, Article International Conference Joint with the 29th International Olympiad in Informatics, IOI 2017, 28 July 2017 through 4 August 2017 ; Volume 11, Issue Special Issue , 2017 , Pages 25-33 ; 18227732 (ISSN) ; Asadi, A ; Jabal Ameli, A ; Seddighin, S. R ; Shahmohammadi, F ; Sharif University of Technology
Vilnius University
2017
A parametric study on residual stresses and forging load in cold radial forging process
, Article International Journal of Advanced Manufacturing Technology ; Volume 33, Issue 1-2 , 2007 , Pages 7-17 ; 02683768 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
2007
Abstract
In this work, a comprehensive study of radial forging process is presented through 2-D axisymmetric and 3-D finite element simulations while considering internal tube profile. The tube used in this investigation has four internal helical grooves along its length. The material is modeled with the elastic-plastic behavior, and sliding-sticking friction model is utilized to model the die-workpiece and mandrel-workpiece contacts. The numerical results in the 2-D case are compared with available experimental data. Residual stresses in the forged product, stress concentration around the grooves, pressure distribution on the hammers and mandrel and maximum forging load are studied. The effects of...
A Lightweight Deep Learning Model for Online Network Traffic
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
Traffic classification is crucial for the execution of many security and managerial tasks in a network, such as identifying malicious data, detecting disruptive users, and preventing the passage of traffic from certain applications. Nowadays, a significant portion of traffic in computer networks is encrypted. Therefore, the classification of encrypted traffic requires the use of solutions for analyzing encrypted traffic. In recent years, many solutions based on machine learning and deep learning have been proposed for analyzing encrypted traffic. While most of these solutions focus on improving the accuracy of network traffic classification, less attention has been paid to their...
Continual Learning Using Unsupervised Data
, M.Sc. Thesis Sharif University of Technology ; Soleymani Baghshah, Mahdieh (Supervisor)
Abstract
The existing continual learning methods are mainly focused on fully-supervised scenarios and are still not able to take advantage of unlabeled data available in the environment. Some recent works tried to investigate semi-supervised continual learning (SSCL) settings in which the unlabeled data are available, but it is only from the same distribution as the labeled data. This assumption is still not general enough for real-world applications and restricts the utilization of unsupervised data. In this work, we introduce Open-Set Semi-Supervised Continual Learning (OSSCL), a more realistic semi-supervised continual learning setting in which out-of-distribution (OoD) unlabeled samples in the...
Modeling interfacial tension of normal alkane-supercritical CO2 systems: Application to gas injection processes
, Article Fuel ; Volume 253 , 2019 , Pages 1436-1445 ; 00162361 (ISSN) ; Hemmati Sarapardeh, A ; Tatar, A ; Zanganeh, A ; Ayatollahi, S ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
To study the gas injection scenario for successful implementation of enhanced oil recovery (EOR)processes, the prediction of interfacial tension (IFT)between injected gas and the crude oil is of paramount significance. In the present study, some intelligent methods were developed for determining IFT values between supercritical CO2 and normal alkanes. IFT was considered as a function of temperature, pressure, and molecular weight of normal alkanes. The developed methods were Multilayer perceptron (MLP), Genetic Algorithm Radial Basis Function (GA-RBF), and Conjugate Hybrid-PSO ANFIS (CHPSO-ANFIS). The average absolute percent relative errors (AAREs)for the stated techniques were found to be...
A dynamic method for feeder reconfiguration and capacitor switching in smart distribution systems
, Article International Journal of Electrical Power and Energy Systems ; Volume 85 , 2017 , Pages 200-211 ; 01420615 (ISSN) ; Ahmadifar, A ; Shariatkhah, M. H ; Vakilian, M ; Haghifam, M. R ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In distribution systems, feeder reconfiguration (FR) can lead to loss reduction, reliability improvement and some other economic savings. These advantages can be intensified by proper control and switching of Capacitor Banks (CBs). In this paper, using Ant Colony Optimization (ACO) technique, a novel method is proposed for simultaneous dynamic scheduling of FR and CB switching in the presence of DG units having uncertain and variant generations over time. This method is applicable to both smart and classic distribution systems. While for the latter, state estimation method should be used to estimate the loads at different buses by employing a limited number of measurements. The objective of...
Secure deep-JSCC against multiple eavesdroppers
, Article Proceedings - IEEE Global Communications Conference, GLOBECOM ; 2023 , Pages 3433-3438 ; 23340983 (ISSN); 979-835031090-0 (ISBN) ; Letafati, M ; Erdemir, E ; Khalaj, B. H ; Behroozi, H ; Gündüz, D ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
In this paper, a generalization of deep learning-aided joint source channel coding (Deep-JSCC) approach to secure communications is studied. We propose an end-to-end (E2E) learning-based approach for secure communication against multiple eavesdroppers over complex-valued fading channels. Both scenarios of colluding and non-colluding eavesdroppers are studied. For the colluding strategy, eavesdroppers share their logits to collaboratively infer private attributes based on ensemble learning method, while for the non-colluding setup they act alone. The goal is to prevent eavesdroppers from inferring private (sensitive) information about the transmitted images, while delivering the images to a...
Effect of heating profile on desorption curve in temperature programmed desorption analysis: Case study of acid sites distribution of SAPO-34
, Article Journal of Porous Materials ; Volume 16, Issue 5 , 2009 , Pages 599-603 ; 13802224 (ISSN) ; Farhadi, F ; Khorasheh, F ; Yan, Z. F ; Sharif University of Technology
2009
Abstract
Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some...
Theoretical and experimental study of cascade solar stills
, Article Solar Energy ; Volume 90 , April , 2013 , Pages 205-211 ; 0038092X (ISSN) ; Sharak, A. Z ; Moghadam, H ; Tabrizi, F. F ; Sharif University of Technology
2013
Abstract
Most part of Iran is dominated by arid and semi-arid areas due to low annual rainfall. The need for production of fresh water from brackish water is considerably high, especially in dry regions. In this study 1 month daily-based experimental data from a solar still site has been reported. The technical and operational problems of this site which finally contributed to the total cease of the site are described. Then a detailed analysis is investigated on progress of a prototype which constructed in order to solve the site's problems. The results of 1 month of experimental data of the final design showed that the last prototype could be used to solve the current problems of the site. The...
Application of a continuous kinetic model for the hydrocracking of vacuum gas oil
, Article Petroleum Science and Technology ; Vol. 32, Issue. 18 , 2014 , Pages 2245-2252 ; ISSN: 10916466 ; Khorasheh, F ; Farhadi, F ; Sharif University of Technology
2014
Abstract
Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and...
An improved methodology for design of custom-made hip prostheses to be fabricated using additive manufacturing technologies
, Article Rapid Prototyping Journal ; Volume 18, Issue 5 , 2012 , Pages 389-400 ; 13552546 (ISSN) ; Abbaszadeh, F ; Farahmand, F ; Sharif University of Technology
Emerald
2012
Abstract
Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance...
Evaluation and enhancing of operational performance and training objective in accordance with Line Operations Safety Audit (LOSA)
, Article International Air Safety Seminar Proceedings, 1 November 2011 through 3 November 2011 ; November , 2011 , Pages 78-99 ; 02705176 (ISSN) ; 9781618393975 (ISBN) ; Goodarzi, F ; Sharafbafi, F ; Sharif University of Technology
2011
Real-time impulse noise suppression from images using an efficient weighted-average filtering
, Article IEEE Signal Processing Letters ; Volume 22, Issue 8 , 2015 , Pages 1050-1054 ; 10709908 (ISSN) ; Hessar, F ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this letter, we propose a method for real-time high density impulse noise suppression from images. In our method, we first apply an impulse detector to identify the corrupted pixels and then employ an innovative weighted-average filter to restore them. The filter takes the nearest neighboring interpolated image as the initial image and computes the weights according to the relative positions of the corrupted and uncorrupted pixels. Experimental results show that the proposed method outperforms the best existing methods in both PSNR measure and visual quality and is quite suitable for real-time applications
Kinetic modeling of pyrolysis of scrap tires
, Article Journal of Analytical and Applied Pyrolysis ; Volume 84, Issue 2 , 2009 , Pages 157-164 ; 01652370 (ISSN) ; Farhadi, F ; Khorasheh, F ; Sharif University of Technology
2009
Abstract
The disposal of used tires is a major environmental problem. With increasing interest on recovery of wastes, pyrolysis is considered as an alternative process for recovering some of the value in scrap tires. An accurate kinetic model is required to predict product yields during thermal or catalytic pyrolysis of scrap tires. Pyrolysis products contain a variety of hydrocarbons over a wide boiling range. A common approach for kinetic modeling of such complex systems is lumping where each lump is defined by a boiling point range. Available experimental data for thermal and catalytic pyrolysis of scrap tires from the literature were used to evaluate two types of lumping models; discrete and...
Determine oil content in petroleum waxes
, Article Hydrocarbon Processing ; Volume 85, Issue 6 , 2006 , Pages 95-97 ; 00188190 (ISSN) ; Yazdani, F ; Farhadi, F ; Sharif University of Technology
2006
Analytical modeling of variable-reluctance tubular resolver based on magnetic equivalent circuit and conformal mapping
, Article IEEE Transactions on Instrumentation and Measurement ; Volume 70 , 2021 ; 00189456 (ISSN) ; Zare, F ; Tootoonchian, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Compared with flat linear structures, tubular linear machines do not face edge effects, making their performance better than their flat counterparts. In this article, a novel linear variable-reluctance resolver with tubular configuration is proposed. To optimize the design of an electromagnetic structure, modeling methods are used. Thus, in this article, an analytical model for the proposed resolver is presented. This model is based on the magnetic equivalent circuit (MEC) method and is considerably less time-consuming than finite element analysis (FEA), yet provides accurate results. A conformal mapping is employed to compute the permeance of the air-gap. The proposed model is then utilized...