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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...
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 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...
On the maximum triangle problem
, Article Scientia Iranica ; Volume 31, Issue 14 , 2024 , Pages 1143-1148 ; 10263098 (ISSN) ; Zarrabi Zadeh, H ; Sharif University of Technology
2024
Abstract
Given a set P of n points in the plane, the maximum triangle problem asks for funding a triangle with three vertices in P that encloses the maximum number of points from P . While the problem is easily solvable in O(n3) time, it has been open whether a subcubic solution is possible. In this paper, we show that the problem can be solved in o(n3) time, using a reduction to min-plus matrix multiplication. We also provide some improved approximation algorithms for the problem, including a 4-approximation algorithm running in O(n log n log h) time, and a 3-approximation algorithm with O(nh log n + nh2) runtime, where h is the size of the convex hull of P . © 2024 Sharif University of Technology
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...
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 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...
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...
A general model for I/O system theory, Proceedings of AIMC31 [electronic resource]
, Article Iranian Journal of Fuzzy Systems ; 2006, Volume 3, Issue 2, Page 1-19 ; Hashem, Amir ; Sharif University of TechnologyIranian 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
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...
Experimental and Numerical Study of Spray Combustion under Hot-diluted Conditions
, M.Sc. Thesis Sharif University of Technology ; Mardani, Amir (Supervisor)
Abstract
In this thesis, combustion of liquid fuel spray under the condition of hot and diluted oxidizer, has been investigated. To this end, a novel type laboratory-scale test rig was designed to study the physics governing the MILD-Spray combustion conditions with an applied approach. The underlined test rig eliminates the operational problems of its predecessor test stands and is used for a heavier fuel with much more complex chemical composition (kerosene). The test section is axially symmetrical, in which the fuel is injected by a pressure-swirl atomizer in the direction of hot and diluted co-flowing air. With the use of the aforesaid test rig, the effect of variables such as oxygen...
General theory of translation invariant systems [electronic resource]
, Article Mathematics and Its Applications ; Volume 329, 1995, pp 77-89 ; Sharif University of Technology
Abstract
The basic goal of this article is to present an abstract system-theoretic approach to morphological filtering and the theory of translation invariant systems which is mainly based on residuated semigroups. Some new results as well as a number of basic questions are also introduced
Duality in a generalized model for translation invariant systems [electronic resource]
, Article Fuzzy Sets and Systems ; 1996, Volume 83, Issue 3, Pages 347–352 ; Sharif University of Technology
Abstract
In a previous paper we introduced a generalized model for translation invariant (TI) operators. In this model we considered the space, φ of all maps from an abelian group G to ω U {-∞}, called LG-fuzzy sets, where ω is a complete lattice-ordered group; and we defined TI operators on this space. Also, in that paper, we proved strong reconstruction theorem to show the consistency of this model. This theorem states that for an order-preserving TI operator Y one can explicitly compute Y(A), for any A, from a specific subset of φ called the base of Y. In this paper duality is considered in the same general framework, and in this regard, continuous TI operators are studied. This kind of operators...
Reconstruction in a generalized model for translation invariant systems [electronic resource]
, Article Fuzzy Sets and Systems ; 1996, Volume 83, Issue 1, Pages 51–55 ; Sharif University of Technology
Abstract
We consider translation invariant (TI) operators on Φ, the set of maps from an abelian group G to Ω ∪ {−∞} , called LG-fuzzy sets, where 0 is a complete lattice ordered group. By defining Minkowski and morphological operations on Φ and considering order preserving operators, we prove a reconstruction theorem. This theorem, which is called the Strong Reconstruction Theorem (SRT), is similar to the Convolution Theorem in the theory of linear and shift invariant systems and states that for an order preserving TI operator Y one can explicitly compute Y ( A ), for any A , from a specific subset of Φ called the base of Y . The introduced framework is a general model for the theory of translation...
Residuated semigroups and morphological aspects of translation invariant systems [electronic resource]
, Article 1997, Volume 90, Issue 1, Pages 69–81 ; Fuzzy Sets and Systems ; Sharif University of Technology
Abstract
The main goal of this paper is to verify classical properties of morphological operators within the general model of translation invariant (TI) systems. In this model, TI operators are defined on the space of LG-fuzzy sets Φ i.e. Φ = {A: G → Ω ∪ {− ∞}} in which G is an abelian group and Ω is a complete lattice ordered group. A TI operator Y is an operator on Φ which is invariant under translation on G and Ω as groups. We consider the generalization of Minkowski addition (D on Φ and we emphasize that (Φ,⊛) is an involutive residuated topological monoid. We verify all properties of traditional (set-theoretic) morphological operators as well as classical representations (Matheron, 1967) for...
Forcing structures and cliques in uniquely vertex colorable graphs [electronic resource]
, Article SIAM Journal on Discrete Mathematics ; 2001, Volume 14, Issue 4, Pages 433-445 ; Sharif University of Technology
Abstract
Let G be a simple undirected uniquely vertex k-colorable graph, or a k-UCG for short. M. Truszczyński [Some results on uniquely colorable graphs, in Finite and Infinite Sets, North-Holland, Amsterdam, 1984, pp. 733--748] introduced $e^{^{*}}(G)=|V(G)|(k-1)-{k \choose 2}$ as the minimum number of edges for a k-UCG and S. J. Xu [J. Combin. Theory Ser. B, 50 (1990), pp. 319--320] conjectured that any minimal k-UCG contains a Kk as a subgraph. In this paper, first we introduce a technique called forcing. Then by applying this technique in conjunction with a feedback structure we construct a k-UCG with clique number k-t, for each $t \geq 1$ and each k, when k is large enough. This also...
Graph homomorphisms and nodal domains [electronic resource]
, Article Linear Algebra and its Applications ; 2006, Volume 418, Issue 1, Pages 44–52 ; Sharif University of Technology
Abstract
In this paper, we derive some necessary spectral conditions for the existence of graph homomorphisms in which we also consider some parameters related to the corresponding eigenspaces such as nodal domains. In this approach, we consider the combinatorial Laplacian and co-Laplacian as well as the adjacency matrix. Also, we present some applications in graph decompositions where we prove a general version of Fisher’s inequality for G-designs