Search for: modularity
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    Fault tolerant operation strategy design for modular multilevel converters

    , Article IECON Proceedings (Industrial Electronics Conference), 24 October 2016 through 27 October 2016 ; 2016 , Pages 2172-2176 ; 9781509034741 (ISBN) Haghnazari, S ; Vahedi, H ; Zolghadri, M. R ; Sharif University of Technology
    IEEE Computer Society  2016
    In this paper a new post fault operation strategy is proposed for modular multilevel converter (MMC). The conventional MMC fault tolerant operation methods use redundant cells in spinning or cold reserve schemes, however in this work the MMC fault tolerant operation is achieved without requiring any redundant cells. The introduced strategy modifies capacitors reference voltages and arms modulation reference waveforms in faulty leg of MMC while other legs operate normally. The applied technique leads to having some degree of overvoltage in faulty leg capacitors which could be neglected since the number of cells is high. Simple realization and significant economic savings would be attained as... 

    Feasibility analysis of the use of rigid polyurethane foam in modular sandwich panels for rapid assembly structures

    , Article International Journal of GEOMATE ; Volume 15, Issue 51 , 2018 , Pages 113-120 ; 21862982 (ISSN) Samali, B ; Nemati, S ; Sharafi, P ; Yaghmaei, F ; Farrokhi, A ; Sharif University of Technology
    GEOMATE International Society  2018
    Mobile and rapidly assembled structures play an important role in building temporary and semi-permanent accommodations and shelters in post-disaster management. One of the most efficient construction systems that can be used in rapidly assembled buildings is lightweight panelized systems. Use of rapidly assembled panelized systems is becoming very popular for cutting the construction time and transportation costs that make them suitable options for rapid assembly construction. In addition, when acoustic and thermal insulation of buildings is important, foam filled composite sandwich panels are an effective solution. Soft, semi-rigid and rigid Polyurethane (PU) foams, which are first... 

    Modular verification of a component-based actor language

    , Article Journal of Universal Computer Science ; Volume 11, Issue 10 , 2005 , Pages 1695-1717 ; 0958695X (ISSN) Sirjani, M ; De Boer, F. S ; Movaghar, A ; Sharif University of Technology
    Rebeca is an actor-based language for modeling concurrent and distributed systems as a set of reactive objects which communicate via asynchronous message passing. Rebeca is extended to support synchronous communication, and at the same time components are introduced to encapsulate the tightly coupled reactive objects which may communicate by synchronous messages. This provide us a language for modeling globally asynchronous and locally synchronous systems. Components interact only by asynchronous messages. This feature and also the eventdriven nature of the computation are exploited to introduce a modular verification approach in order to overcome the state explosion problem in model... 

    Model checking, automated abstraction, and compositional verification of Rebeca models

    , Article Journal of Universal Computer Science ; Volume 11, Issue 6 , 2005 , Pages 1054-1082 ; 0958695X (ISSN) Sirjani, M ; Movaghar, A ; Shali, A ; De Boer, F. S ; Sharif University of Technology
    Actor-based modeling, with encapsulated active objects which communicate asynchronously, is generally recognized to be well-suited for representing concurrent and distributed systems. In this paper we discuss the actor-based language Rebeca which is based on a formal operational interpretation of the actor model. Its Java-like syntax and object-based style of modeling makes it easy to use for software engineers, and its independent objects as units of concurrency leads to natural abstraction techniques necessary for model checking. We present a front-end tool for translating Rebeca to the languages of existing model checkers in order to model check Rebeca models. Automated modular... 

    Modularity of Semi-stable Elliptic Curves

    , M.Sc. Thesis Sharif University of Technology Mahkam, Roohallah (Author) ; Jafari, Amir (Supervisor)
    Let E be a semi-stable elliptic curve over Q with conductor N and L(E,s) as its L-function. We say that E is modular if there exists an eigenform of weight 2 and level N over X_0(N) such that L(E,s) equals the L-function of f or L(E,s)=L(f,s). Wilse's method to prove this was by proving that the Galois representations induced by E and f are equivalent. First we will discuss that equivalency of those representations is equivalent to equality of L-functions and after that we will use deformation theory for Galois representations to overlook the main ideas of the proof of the modularity theorem. Wiles using the idea of deformation of Galois representaions proved that under proper conditions... 

    Improved iterative techniques to compensate for interpolation distortions

    , Article Signal Processing ; Volume 92, Issue 4 , 2012 , Pages 963-976 ; 01651684 (ISSN) Parandehgheibi, A ; Ayremlou, A ; Akhaee, M. A ; Marvasti, F ; Sharif University of Technology
    In this paper a novel hybrid algorithm for compensating the distortion of any interpolation has been proposed. In this Hybrid method, a modular approach was incorporated in an iterative fashion. The proposed technique features an impressive improvement at reduced computational complexity. The authors also extend the scheme to 2-D signals and actual (real) images and find that the solution exhibits great potential. Both the simulation results and mathematical analysis confirm the superiority of the Hybrid model over competing methods and demonstrate its robustness against additive noise  

    Cascading failure tolerance of modular small-world networks

    , Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 58, Issue 8 , 2011 , Pages 527-531 ; 15497747 (ISSN) Babaei, M ; Ghassemieh, H ; Jalili, M ; Sharif University of Technology
    Many real-world networks have a modular structure, and their component may undergo random errors and/or intentional attacks. More devastating situations may happen if the network components have a limited load capacity; the errors and attacks may lead to a cascading component removal process, and consequently, the network may lose its desired performance. In this brief, we investigate the tolerance of cascading errors and attacks in modular small-world networks. This brief studies the size of the largest connected component of the networks when cascading errors or attacks occur. The robustness of the network is tested as a function of both the intermodular connection and intramodular... 

    Fully Homomorphic Encryption Implementation

    , M.Sc. Thesis Sharif University of Technology Heydarian, Mohammad Javad (Author) ; Shabany, Mahdi (Supervisor)
    After being introduced in 2009, the first fully homomorphic encryption (FHE) scheme has created significant excitement in academia and industry. Despite rapid advances in the last 6 years, FHE schemes are still not ready for deployment due to an efficiency bottleneck. Here we introduce a hardware/software codesign, in fact a hardware accelerator optimized for a class of reconfigurable logic to bring homomorphic encryption schemes one step closer to deployment in real-life applications. The accelerator we present is connected via a fast PCIe interface to a CPU platform to provide homomorphic evaluation services to any application that needs to support blinde computations. Specifically we... 

    A framework for extending agile methodologies with aspect-oriented features

    , Article Proceedings - International Conference on Research Challenges in Information Science, 19 May 2011 through 21 May 2011, Gosier ; 2011 ; 21511349 (ISSN) ; 9781424486694 (ISBN) Gerami, M ; Ramsin, R ; Sharif University of Technology
    Aspect-Oriented Software Development (AOSD) concentrates on determination and modularization of orthogonal concerns that cut across system modules. An aspect-oriented extension framework helps transform existing methodologies into processes which support AOSD. The authors propose a framework for extending agile methodologies with AOSD features. The stages required for constructing the framework have been identified by scrutinizing existing aspect-oriented methodologies and practices in order to extract the AOSD-specific stages required in each phase of the agile development process. Analysis shows that a methodology extended through this framework can be superior in agility in comparison to... 

    Compensating for distortions in interpolation of two-dimensional signals using improved iterative techniques

    , Article ICT 2010: 2010 17th International Conference on Telecommunications, 4 April 2010 through 7 April 2010 ; April , 2010 , Pages 929-934 ; 9781424452477 (ISBN) ParandehGheibi, A ; Rahimian, M. A ; Akhaee, M. A ; Ayremlou, A ; Marvasti, F ; Sharif University of Technology
    In this paper we extended a previously investigated modular method that is designed to compensate for interpolation distortions of one-dimensional signals, to two dimensions (2-D). Next the proposed 2-D modular technique was applied in an iterative fashion and was shown through both simulations and theoretical analyses to enhance the convergence of the iterative technique. In fact, with only a few modules we were able to achieve drastic improvements in signal reconstruction, and with a much less computational complexity. Moreover, both the simulations and the theoretical analysis confirmed the robustness of the proposed scheme against additive noise  

    A novel voltage measurement technique for modular multilevel converter capacitors

    , Article 41st Annual Conference of the IEEE Industrial Electronics Society, 9 November 2015 through 12 November 2015 ; 2015 , Pages 238-243 ; 9781479917624 (ISBN) Haghnazari, S ; Zolghadri, M. R ; IEEE Industrial Electonics Society (IES) ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    In this paper a new voltage measurement technique for modular multilevel converter (MMC) capacitors is proposed. While all the capacitors voltages should be known for closed loop control of MMCs, only the arms voltages are measured employing the proposed method. Therefore, the number of voltage sensors reduced dramatically to one per arm. The capacitors voltage quantities are updated continuously using the arms voltage and the switching signals. Although the proposed method precision is depended on the equality of the capacitors, presented investigations show that the steady state error and even transient error in capacitors voltage estimation is ignorable for the proper operation of the... 

    A new fault detection method for modular multilevel converter semiconductor power switches

    , Article 41st Annual Conference of the IEEE Industrial Electronics Society, 9 November 2015 through 12 November 2015 ; 2015 , Pages 50-55 ; 9781479917624 (ISBN) Haghnazari, S ; Shahbazi, M ; Zolghadri, M. R ; IEEE Industrial Electonics Society (IES) ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    This paper proposes a new fault detection method for the modular multilevel converter (MMC) semiconductor power switches. While in common MMCs, the modules capacitor voltages are measured directly for control purposes, in this paper voltage measurement point changes to module output terminal improving fault diagnosis ability. Based on this measurement reconfiguration, a novel fault detection algorithm is designed for MMCs semiconductor power switches. The open circuit and short circuit faultsare detected based on unconformity between modules output voltage and switching signals. Simulations results confirm accurate and fast operation of the proposed algorithm in faulty module diagnosis.... 

    Complexity of the improper twin edge coloring of graphs

    , Article Graphs and Combinatorics ; Volume 33, Issue 4 , 2017 , Pages 595-615 ; 09110119 (ISSN) Abedin, P ; Akbari, S ; Demange, M ; Ekim, T ; Sharif University of Technology
    Let G be a graph whose each component has order at least 3. Let s: E(G) → Zk for some integer k≥ 2 be an improper edge coloring of G (where adjacent edges may be assigned the same color). If the induced vertex coloring c: V(G) → Zk defined by c(v)=∑e∈Evs(e)inZk, (where the indicated sum is computed in Zk and Ev denotes the set of all edges incident to v) results in a proper vertex coloring of G, then we refer to such a coloring as an improper twin k-edge coloring. The minimum k for which G has an improper twin k-edge coloring is called the improper twin chromatic index of G and is denoted by χit′(G). It is known that χit′(G)=χ(G), unless χ(G)≡2(mod4) and in this case χit′(G)∈{χ(G),χ(G)+1}.... 

    Full characterization of a spin liquid phase: From topological entropy to robustness and braid statistics

    , Article Journal of Physics A: Mathematical and Theoretical ; Volume 50, Issue 14 , 2017 ; 17518113 (ISSN) Jahromi, S. S ; Langari, A ; Sharif University of Technology
    Institute of Physics Publishing  2017
    We use the topological entanglement entropy (TEE) as an efficient tool to fully characterize the Abelian phase of a Z2 ×Z2 spin liquid emerging as the ground state of topological color code (TCC), which is a class of stabilizer states on the honeycomb lattice. We provide the fusion rules of the quasiparticle (QP) excitations of the model by introducing single- or two-body operators on physical spins for each fusion process which justify the corresponding fusion outcome. Besides this, we extract the TEE from Renyi entanglement entropy (EE) of the TCC, analytically and numerically by finite size exact diagonalization on the disk shape regions with contractible boundaries. We obtain that the EE... 

    Ihara-Type results for siegel modular forms

    , Article Bulletin of the Iranian Mathematical Society ; Volume 46, Issue 3 , 2020 , Pages 693-716 Rastegar, A ; Sharif University of Technology
    Springer  2020
    Let p be a prime not dividing the integer n. By an Ihara result, we mean existence of a cokernel torsion-free injection from a full lattice in the space of p-old modular forms into a full lattice in the space of all modular forms of level pn. In this paper, we will prove an Ihara result in the number field case, for Siegel modular forms. The case of elliptic modular forms is discussed in Ihara (Discrete subgroups of Lie groups and applications to moduli, Oxford University Press, Bombay, 1975). We will use a geometric formulation for the notion of p-old Siegel modular forms (Rastegar in BIMS 43(7):1–23, 2017). Then, we apply an argument by Pappas, and prove the Ihara result using density of... 

    Integrating module checking and deduction in a formal proof for the perlman Spanning Tree Protocol (STP)

    , Article Journal of Universal Computer Science ; Volume 13, Issue 13 , 2007 , Pages 2076-2104 ; 0958695X (ISSN) Hojjat, H ; Nakhost, H ; Sirjani, M ; Sharif University of Technology
    In the IEEE 802.1D standard for the Media Access Control layer (MAC layer) bridges, there is an STP (Spanning Tree Protocol) definition, based on the algorithm that was proposed by Radia Perlman. In this paper, we give a formal proof for correctness of the STP algorithm by showing that finally a single node is selected as the root of the tree and the loops are eliminated correctly. We use formal inductive reasoning to establish these requirements. In order to ensure that the bridges behave correctly regardless of the topology of the surrounding bridges and LANs, the Rebeca, modular verification techniques are applied. These techniques are shown to be efficiently applicable in model checking... 

    Eigenvalue determination by mixed modular networks

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 28, Issue B1 , 2004 , Pages 31-41 ; 10286284 (ISSN) Joghataie, A ; Kamali, M. T ; Sharif University of Technology
    Smart systems in general, and specifically neural networks, are expected to be of great assistance in large scale matrix computation. However it was necessary to work with smaller problems at first step. To this end, a method based on using perceptrons and Kohonen networks for determining the first three modal frequencies of frames of up to 20 stories high and two bays wide from their stiffness and mass matrices, was developed. This paper introduces this modular network as a preferable alternative for designing smart systems for learning large scale mapping problems in structural engineering, and in addition, reports the successful application of this modular network to the eigenvalue and... 

    Investigating optimum procedures needed to maintain a model satellite's CG stable about design point, under subsystem configuration changes

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 4 , 2010 , Pages 585-588 ; 9780791849187 (ISBN) Dastoom Laatleyli, H ; Abedian, A ; Teimouri, H ; Sharif University of Technology
    During design, microsatellites are subject to different changes like the changes in weight, location and dimension of parts and elements of subsystems and the payload. These changes should be accumulated by the structure subsystem in a way that some key structural parameters like the center of gravity (CG) and inertia moments remain unchanged. This subject is also important regarding the design of a modular structure of a satellite. In the present study it is tried to accommodate any changes in weight and location of any part(s) and element(s) of a microsatellite by optimum (minimum) rearrangement of other parts on their plane of rest in order to keep the CG and inertia moments unchanged.... 

    Community Detection in Very Large Networks

    , M.Sc. Thesis Sharif University of Technology Goli, Amir Hossein (Author) ; Beigy, Hamid (Supervisor)
    Nowadays Systems in different fields of research like computer science, biology, social networks, information networks, and economics are modeled as graphs. The graphs which model real world systems have very different topological characteristics than those of classic networks. One of the prominent characteristics of these networks, is that its not practical to describe a general model for their structure and behavior. As a consequence of this complexity in modeling and structure, these networks are called complex networks. One of the most important observations in complex networks is the presence of communities, it means that in such networks one can separate vertices in disjoint sets, such... 

    Finding Proper Modular Robots Structure by Using Genetic Algorithm

    , M.Sc. Thesis Sharif University of Technology Haghzad Klidbary, Sajad (Author) ; Bagheri Shouraki, Saeed (Supervisor)
    Modular Robots are group of robots which are made of small components called modules. The advantage of these robots to others is their ability to change physical configuration. Using of these robots in configuration changing due to environmental conditions is popular. While, reconfiguration is one of the most important features in modular robot, it’s the most important concern too. Path planning problem is one of the important problems in robotics .So far, most of presented path planning methods and algorithms are based on fixed-structure and they had little attention to path planning and configuration changing, simultaneously. In this thesis, the Genetic Algorithm is used to find path and...