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    Algebraic bound for the phase–frequency response of the commande robuste d'ordre non-entier approximation of fractional differentiators and its applications in control systems analysis

    , Article JVC/Journal of Vibration and Control ; 2021 ; 10775463 (ISSN) Neshat, K ; Tavazoei, M. S ; Sharif University of Technology
    SAGE Publications Inc  2021
    This article deals with analyzing the phase–frequency response of commande robuste d'ordre non-entier approximations of fractional-order differentiators. More precisely, an algebraic tight upper bound is derived for the phase of the approximations obtained from the commande robuste d'ordre non-entier method. Then, some applications for this achievement are discussed in the viewpoint of control systems analysis. These applications include usefulness of the obtained upper bound in stability preservation analysis during the commande robuste d'ordre non-entier–based approximation process and applicability of such a bound in finding necessary or sufficient conditions for test of positive... 

    Storage-aware value prediction

    , Article Proceedings - 13th Euromicro Conference on Digital System Design: Architectures, Methods and Tools, DSD 2010, 1 September 2010 through 3 September 2010, Lille ; 2010 , Pages 722-728 ; 9780769541716 (ISBN) Salehi, M ; Baniasadi, A ; Sharif University of Technology
    Despite the huge potential, value predictors have not been used in modern processors. This is partially due to the complex structures associated with such predictors. In this paper we study value predictors and investigate solutions to reduce storage requirements while imposing negligible coverage cost. Our solutions build on the observation that conventional value predictors do not utilize storage efficiently as they allocate too much space for small and frequently appearing values. We measure data width requirement and entropy in a subset of predictor resources and show that values stored in predictors show limited sizes and very small entropy. We exploit this behavior and suggest... 

    Control and manipulation of multibody objects

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 579-584 ; 9780791849170 (ISBN) Beigzadeh, B ; Meghdari, A ; Sohrabpour, S ; Sharif University of Technology
    In this work, we study a kind of manipulation process during which we deal with active objects. An active object is a concept covering a variety of objects that are not rigid and need to be controlled during the manipulation process. Here, we use a multi-link mechanism with active motors (actuator) as the object and a series of simple planar manipulators to perform the manipulation process. Dynamic, control, motion planning, and stability at the presence of impact are the most important challenges in this work  

    Singularity reduction of a 3-UPS mechanism with 6 DOF for haptic applications

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 3 , 2010 , Pages 619-626 ; 9780791849170 (ISBN) Vossoughi, G. R ; Khodabakhsh, M ; ASME Turkey Section ; Sharif University of Technology
    A method for singularity reduction in a triangular 3-UPS mechanism is discussed. This mechanism usually has singularity near the origin. Changing the active joint angle can arrive at a suitable workspace near the origin without any singularity. Moreover, a 4-UPS mechanism, based on adding one additional leg to the 3-UPS mechanism, has a larger singular free workspace. Moreover, force analysis of two different mechanisms shows a reasonable and consistent force distribution between the different actuators. Singular free workspace is one of the characteristics which makes this mechanism ideal for haptic applications  

    Renormalization of entanglement in the anisotropic Heisenberg (XXZ) model

    , Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 77, Issue 3 , 2008 ; 10502947 (ISSN) Kargarian, M ; Jafari, R ; Langari, A ; Sharif University of Technology
    We have applied our recent approach to study the quantum-information properties of the anisotropic s=1/2 Heisenberg chain. We have investigated the underlying quantum-information properties such as the evolution of concurrence, entanglement entropy, nonanalytic behaviors, and the scaling close to the quantum critical point of the model. Both the concurrence and the entanglement entropy develop two saturated values after enough iterations of the renormalization of coupling constants. These values are associated with the two different phases, i.e., Néel and spin liquid phases. The nonanalytic behavior comes from the divergence of the first derivative of both measures of entanglement as the... 

    Renormalization of concurrence: The application of the quantum renormalization group to quantum-information systems

    , Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 76, Issue 6 , 20 December , 2007 ; 10502947 (ISSN) Kargarian, M ; Jafari, R ; Langari, A ; Sharif University of Technology
    We have combined the idea of renormalization group and quantum-information theory. We have shown how the entanglement or concurrence evolve as the size of the system becomes large, i.e., the finite size scaling is obtained. Moreover, we introduce how the renormalization-group approach can be implemented to obtain the quantum-information properties of a many-body system. We have obtained the concurrence as a measure of entanglement, its derivatives and their scaling behavior versus the size of system for the one-dimensional Ising model in transverse field. We have found that the derivative of concurrence between two blocks each containing half of the system size diverges at the critical point... 

    Unreliability of frequency-domain approximation in recognising chaos in fractional-order systems

    , Article IET Signal Processing ; Volume 1, Issue 4 , December , 2007 , Pages 171-181 ; 17519675 (ISSN) Tavazoei, M. S ; Haeri, M ; Sharif University of Technology
    The effects of using frequency-domain approximation in numerical simulation of fractional-order systems are analytically studied. The main aim in the study is to determine the number, location and stability property of the equilibriums in a fractional-order system and its frequency-based approximating counterpart. The comparison shows that the original fractional-order system and its frequency-based approximation may differ from each other in some or all issues considered in the study. Unfortunately, these differences can lead to wrong consequences in some special cases such as detecting chaos in the fractional-order systems. It is shown that using the frequency-domain approximation methods... 

    Anti-synchronization of two different chaotic systems via active control

    , Article Wec 05: Fourth World Enformatika Conference, Istanbul, 24 June 2005 through 26 June 2005 ; Volume 6 , 2005 , Pages 62-65 ; 9759845857 (ISBN); 9789759845858 (ISBN) Emadzadeh, A. A ; Haeri, M ; Sharif University of Technology
    This paper presents anti-synchronization of chaos between two different chaotic systems using active control method. The proposed technique is applied to achieve chaos antisynchronization for the Lu and Rössler dynamical systems. Numerical simulations are implemented to verify the results. COPYRIGHT © ENFORMATIKA  

    A finite volume central differencing scheme for simulation of the shut down procedure of a hydraulic system

    , Article International Journal of Fluid Power ; Volume 3, Issue 2 , 2002 , Pages 17-27 ; 14399776 (ISSN) Mazaheri, K ; Farahani, R. H ; Sharif University of Technology
    A new central differencing finite volume scheme is investigated for solution of unsteady hydraulic problems as water hammer in pipe systems. Special time stepping procedure similar to Runge-Kutta algorithm is used to stabilize this second order scheme. It is monotonized by adding dissipative terms including second and fourth derivatives of the conserved variables, with coefficients proportional to derivatives of pressure or volumetric flow, which keeps the second order of accuracy in smooth flow regions. The one-dimensional unsteady incompressible equations are solved for a water hammer situation, and results are compared to existing analytical solutions. Results are also compared with... 

    Improvement of the axial power distribution control capabilities in VVER-1000 reactors

    , Article Annals of Nuclear Energy, Exeter ; Volume 27, Issue 10 , 2000 , Pages 949-957 ; 03064549 (ISSN) Yousefpour, F ; Ghofrani, M. B ; Sharif University of Technology
    Elsevier Science Ltd  2000
    This article describes an automatic reactor power control system for VVER-1000 reactor and reports simulation analysis results for a typical daily load follow operation. The associated reactor control algorithm is called `mode G' that uses a heavy-worth bank (H-bank) dedicated to axial power shape control and the light-gray banks (G-banks) for reactor power change and reactivity compensation. The simulation results for daily load follow operation in three burnup states of first cycle illustrate that the load follow capability of VVER-1000 reactors using this algorithm will be improved  

    Analyzing organizational capabilities as systems: A conceptual framework

    , Article 18th International Dependency and Structure Modeling Conference: Sustainability in Modern Project Management, DSM 2016, 29 August 2016 through 30 August 2016 ; 2016 , Pages 67-76 Arasti, M ; Khaleghi, M ; Sharif University of Technology
    International Dependency and Structure Modeling Conference  2016
    Operational capabilities are used in resource based view in strategic management literature to explain how the difference in performing similar activities results in heterogeneity between firms. In order to advance our understanding of this concept, using a system metaphor, we try to shape a framework for micro-level analysis of operational capabilities. Following two stages of holism and focus for identifying system boundaries through looking related literatures, we propose knowledge, skills and tools as general micro elements of operational capabilities in form domain. Using Dependency Structure Matrix (DSM), we finally synthesize our conceptual framework to capture interactions of... 

    Standard test systems for modern power system analysis: an overview

    , Article IEEE Industrial Electronics Magazine ; Volume 13, Issue 4 , 2019 , Pages 86-105 ; 19324529 (ISSN) Peyghami, S ; Davari, P ; Fotuhi Firuzabad, M ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    The reliable design, planning, and operation of power systems are of paramount importance for providing reliable services to customers. This article reviews the different aspects of power system reliability, ranging from planning to operation. Standard benchmarks employed for power system studies are reviewed according to nearly 2,500 IEEE journal papers from 1986 to early 2019. Our overview provides the pros and cons of existing test systems, implying the lack of appropriate benchmarks for future power system studies, including renewable resources and modern technologies. Furthermore, this article presents requirements for updating and modifying the benchmarks for modern power systems... 

    Addition of learning to critic agent as a solution to the multi-agent credit assignment problem

    , Article ICSCCW 2009 - 5th International Conference on Soft Computing, Computing with Words and Perceptions in System Analysis, Decision and Control, 2 September 2009 through 4 September 2009 ; 2009 ; 9781424434282 (ISBN) Rahaie, Z ; Beigy, H ; Sharif University of Technology
    Multi-agent systems (MAS) is a solution to the nowadays encountered problems, which have the characteristics such as distributiveness, dynamism and the need to adaptation, robustness, efficiency, and reusability. This paper proposed a solution to multi-agent credit assignment problem. The contribution is to equip the critic agent (who is responsible for distributing reinforcements among agents) with learning capability. Some criteria are used to propose an inner feedback to the critic. Results of simulation show the applicability of the method to a task, which has the characteristic that the agent has to decide from a large set of actions. The research is a preliminary step to more in-depth... 

    A new analytical approach in modeling of multi-loop feed-forward linearized microwave power amplifiers

    , Article AEU - International Journal of Electronics and Communications ; Volume 62, Issue 6 , 2008 , Pages 421-429 ; 14348411 (ISSN) Afshin Hemmatyar, A. M ; Farzaneh, F ; Sharif University of Technology
    Elsevier GmbH  2008
    Feed-forward is one of the main methods for linearization of microwave power amplifiers. Although the complexity of the system is increased, the level of inter-modulation rejection (IMR) of a feed-forward system can be improved using a multi-loop configuration. Predicting the IMR of such a system is of prime importance. A new analytical approach in modeling a multi-loop feed-forward system for predicting the linearization performance of the system is presented. The first loop of the multi-loop system is substituted by an equivalent amplifier model and then the reduced system as a new feed-forward system is evaluated. The predicted IMR values are verified using the ADS simulator and a MATLAB... 

    Design and application of industrial machine vision systems

    , Article Robotics and Computer-Integrated Manufacturing ; Volume 23, Issue 6 , December , 2007 , Pages 630-637 ; 07365845 (ISSN) Golnabi, H ; Asadpour, A ; Sharif University of Technology
    In this paper, the role and importance of the machine vision systems in the industrial applications are described. First understanding of the vision in terms of a universal concept is explained. System design methodology is discussed and a generic machine vision model is reported. Such a machine includes systems and sub-systems, which of course depend on the type of applications and required tasks. In general, expected functions from a vision machine are the exploitation and imposition of the environmental constraint of a scene, the capturing of the images, analysis of those captured images, recognition of certain objects and features within each image, and the initiation of subsequent... 

    Measuring the geometrical parameters of steel billets during molding process using image processing

    , Article 6th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2006, Vancouver, BC, 27 August 2006 through 30 August 2006 ; 2006 , Pages 59-63 ; 0780397541 (ISBN); 9780780397545 (ISBN) Mohammadiha, N ; Sahraeian, M ; Vosoughi Vahdat, B ; Azizi, A ; Ahmadi, A. S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    This paper presents a designed system for measuring three dimensions (height, width and length) of steel billets during molding process. The system has been equipped with a GigaEthernet camera and an industrial computer (IPC). The billet is moved in front of the inspection system with an external moving mechanism. Image processing techniques and calibration are used to measure dimensions from the succeeding single view images. ©2006 IEEE  

    DBMSS: An event-based simulator for analyzing concurrency protocols in database systems

    , Article 2006 Canadian Conference on Electrical and Computer Engineering, CCECE'06, Ottawa, ON, 7 May 2006 through 10 May 2006 ; 2006 , Pages 1874-1877 ; 08407789 (ISSN); 1424400384 (ISBN); 9781424400386 (ISBN) Jalali, L ; Abdollahzadeh, A ; Aliakbarian, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    This paper explores design and implementation of an event-based simulator namely DBMSS for analyzing concurrency protocols in database systems. In the design of DBMSS we interested in event-based approach to create a real world with variety range of event possibilities. DBMSS is explored in the context of the development of a complex simulator for simulating real world conditions and provide an event-based environment to test and evaluate concurrency protocols in database systems. First we discuss the architecture of DBMSS and use it to provide arrival transactions to test and evaluate concurrency protocols in database system. We present the comparison of 4 concurrency protocols in variety... 

    Feedforward multiple-input active noise control systems

    , Article 2003 ASME International Mechanical Engineering Congress, Washington, DC., 15 November 2003 through 21 November 2003 ; Volume 72, Issue 1 , 2003 , Pages 143-150 Ohadi, A. R ; Mehdigholl, H ; Esmailzadeh, E ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2003
    The use of adaptive feedforward controllers has proven to be a very successful strategy for controlling noise and vibration in a variety of applications. One reason is that the feedforward controller is an open loop controller, which can be designed to cancel the undesired noise in one position with any accuracy. However, the feedforward controller requires an input signal, called a reference signal, correlated to the noise source. As a consequence, a single reference controller can only reduce noise radiated from a single noise source. In many applications, there is a need to attenuate noise produced by several noise sources. In this paper, three different structures, single, modulating and... 

    Supporting non-contiguous processor allocation in mesh-based CMPs using virtual point-to-point links

    , Article Proceedings -Design, Automation and Test in Europe, DATE ; 2011 , p. 413-418 ; ISSN: 15301591 ; ISBN: 9783981080179 Asadinia, M ; Modarressi, M ; Tavakkol, A ; Sarbazi-Azad, H ; Sharif University of Technology
    In this paper, we propose a processor allocation mechanism for run-time assignment of a set of communicating tasks of input applications onto the processing nodes of a Chip Multiprocessor (CMP), when the arrival order and execution lifetime of the input applications are not known a priori. This mechanism targets the on-chip communication and aims to reduce the power and latency of the NoC employed as the communication infrastructure. In this work, we benefit from the advantages of non-contiguous processor allocation mechanisms, by allowing the tasks of the input application mapped onto disjoint regions (sub-meshes) and then virtually connecting them by bypassing the router pipeline stages of... 

    Kinematic effects of gimbal joints on a 3URU parallel manipulator

    , Article ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis, ESDA 2012 ; Volume 3 , 2012 , Pages 205-210 ; 9780791844861 (ISBN) Baghi, S ; Razban, F ; Osgouie, K. G ; Sharif University of Technology
    Gimbal transmissions are non-linear direct transmissions and can be used in robotic arms replacing the traditional revolute joints. They offer potential advantages for critical cases such as joint space and task space singularities or where a different mechanical advantage is needed compared to what traditional revolute joints provide. This can be obtained by properly adjusting the different parameters of Gimbal joints used in different joints of the manipulator (such as their offset angle and/or chamfer angle). In this paper the concept of Gimbal mechanism as a joint is investigated. Then, as an example, Gimbal joints are used to replace the basic revolute joints of a 3-UPU parallel...