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Stabilizing control structures: An optimization framework
, Article IEEE Transactions on Automatic Control ; 2021 ; 00189286 (ISSN) ; Babazadeh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
This paper presents a new optimization-based approach to determine the class of stabilizing control structures with the necessary set of feedback links for interconnected systems. The proposed approach relies on a graph theoretic interpretation and its equivalence in terms of binary linear programs (BLP). To carry out the primary goal, first, the stabilizability of an LTI system under the decentralized control structure is presented in terms of a BLP. Next, two graph-based criteria are proposed to characterize stabilizing control structures with the required feedback links. Finally, all possible stabilizing control structures with the necessary feedback links are derived via solving a set of...
Computational analysis of heat and mass transfer in a micropolar fluid flow through a porous medium between permeable channel walls
, Article International Journal of Nonlinear Sciences and Numerical Simulation ; 2021 ; 15651339 (ISSN) ; Ashraf, M ; Ali, K ; Nisar, K. S ; Sharif University of Technology
De Gruyter Open Ltd
2021
Abstract
The present work numerically investigates the mass and heat transport flow of micropolar fluid in a channel having permeable walls. The appropriate boundary layer approximations are used to convert the system of flow model equations in ODEs, which are then numerically treated with the quasi-linearization method along with finite difference discretization. This technique creates an efficient way to solve the complex dynamical system of equations. A numerical data comparison is presented which assures the accuracy of our code. The outcomes of various problem parameters are portrayed via the graphs and tables. The concentration and temperature accelerate with the impacts of the Peclet numbers...
Computational analysis of heat and mass transfer in a micropolar fluid flow through a porous medium between permeable channel walls
, Article International Journal of Nonlinear Sciences and Numerical Simulation ; 2021 ; 15651339 (ISSN) ; Ashraf, M ; Ali, K ; Nisar, K. S ; Sharif University of Technology
De Gruyter Open Ltd
2021
Abstract
The present work numerically investigates the mass and heat transport flow of micropolar fluid in a channel having permeable walls. The appropriate boundary layer approximations are used to convert the system of flow model equations in ODEs, which are then numerically treated with the quasi-linearization method along with finite difference discretization. This technique creates an efficient way to solve the complex dynamical system of equations. A numerical data comparison is presented which assures the accuracy of our code. The outcomes of various problem parameters are portrayed via the graphs and tables. The concentration and temperature accelerate with the impacts of the Peclet numbers...
Optimization-based distribution system reliability evaluation: An enhanced MILP model
, Article 4th International Conference on Smart Energy Systems and Technologies, SEST 2021, 6 September 2021 through 8 September 2021 ; 2021 ; 9781728176604 (ISBN) ; Lehtonen, M ; Fotuhi Firuzabad, M ; Munoz Delgado, G ; Contreras, J ; Arroyo, J. M ; University of Vaasa ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Standard mathematical-programming-based models have attracted considerable attention for optimizing distribution system planning and operation due to their salient advantages. More specifically, mixed-integer linear programming (MILP) has proven very effective in modeling such problems. The availability of optimization software for efficiently solving MILP problems with guaranteed convergence to optimality while providing a measure of the distance to the optimal solution has made MILP models more popular. Although a plethora of efficient MILP formulations have been proposed for planning and operating studies of distribution grids, incorporating reliability into such models is still...
Identification of a linearized Fitzhugh-nagumo neuron model using a combinational multi layer perceptron network
, Article Proceedings of the 14th IASTED International Conference on Applied Simulation and Modelling, Benalmadena, 15 June 2005 through 17 June 2005 ; 2005 , Pages 144-149 ; 0889864691 (ISBN) ; Sadughi, S ; Hamza M. H ; Sharif University of Technology
2005
Abstract
In this paper, the authors have focused their attention on developing a model, which is capable of being identified so that it mimics faithfully the behavior of an individual physiological neuron from input-output point of view. A hierarchical method is introduced to identify the parameterized nonlinear FN equation with respect to the achieved input-output data from a physiological trial on a neuron. In this hierarchy, four steps are outstanding, which are: linearization of nonlinear FN in the rest regime of Action Potential, identification of the parameters of this linear system with hard data, substitution of achieved parameters in original nonlinear system and finally, fine tuning the...
A low-order H∞ controller design for an active suspension system via linear matrix inequalities
, Article JVC/Journal of Vibration and Control ; Volume 10, Issue 8 , 2004 , Pages 1181-1197 ; 10775463 (ISSN) ; Sadati, N ; Sharif University of Technology
2004
Abstract
We present an application of a new controller order reduction technique with stability and performance preservation based on linear matrix inequality optimization to an active suspension system. In this technique, the rank of the residue matrix of a proper rational approximation of a high-order H ∞ controller subject to the H∞ norm of a frequency-weighted error between the approximated controller and high-order H∞ controller is minimized. However, since solving this matrix rank minimization problem is very difficult, the rank objective function is replaced with the nuclear-norm that can be reduced to a semidefinite program, so that it can be solved efficiently. Application to the active...
H∞ formulation of decentralized stabilization problem
, Article Proceedings of the Thirty-Sixth Southeastern Symposium on System Theory (SSST04), Atlanta, GA., 14 March 2004 through 16 March 2004 ; Volume 36 , 2004 , Pages 79-83 ; Sadati, N ; Sharif University of Technology
2004
Abstract
This paper considers the problem of stabilizing a class of linear time-invariant large-scale systems composed of a number of subsystems using several local dynamic output feedback controllers. For this problem, a sufficient condition on each closed-loop individual subsystem is derived under which the decentralized controller composed of the local controllers designed for individual subsystems, achieves stability for the overall system. This condition is used to convert the decentralized stabilization problem to a set of the H∞ disturbance rejection subproblems
A sufficient condition for decentralized stabilization
, Article Iranian Journal of Electrical and Computer Engineering ; Volume 3, Issue 2 , 2004 , Pages 175-179 ; 16820053 (ISSN) ; Sadati, N ; Sharif University of Technology
2004
Abstract
This paper considers the problem of stabilizing a class of linear time-invariant large-scale systems composed of a number of subsystems using several local dynamic output feedback controllers. For this problem, a sufficient condition on each closed-loop individual subsystem is derived under which the decentralized controller composed of the local controllers designed for individual subsystems, achieves stability for the overall system. This condition is used to convert the decentralized stabilization problem to a set of the H∞ disturbance rejection subproblems
Maximal subgroups of GL n (D)
, Article Journal of Algebra ; Volume 259, Issue 1 , 2003 , Pages 201-225 ; 00218693 (ISSN) ; Ebrahimian, R ; Momenaee Kermani, H ; Salehi Golsefidy, A ; Sharif University of Technology
Academic Press Inc
2003
Abstract
In this paper we study the structure of locally solvable, solvable, locally nilpotent, and nilpotent maximal subgroups of skew linear groups. In [S. Akbari et al., J. Algebra 217 (1999) 422-433] it has been conjectured that if D is a division ring and M a nilpotent maximal subgroup of D*, then D is commutative. In connection with this conjecture we show that if F[M]F contains an algebraic element over F, then M is an abelian group. Also we show that ℂ* ∪ ℂ*j is a solvable maximal subgroup of real quaternions and so give a counterexample to Conjecture 3 of [S. Akbari et al., J. Algebra 217 (1999) 422-433], which states that if D is a division ring and M a solvable maximal subgroup of D* then...
Active control of trusses under heavy static loads
, Article Neural Network World ; Volume 11, Issue 3 , 2001 , Pages 285-292 ; 12100552 (ISSN) ; Sharif University of Technology
2001
Abstract
Trusses are suitable load-bearing structural systems for heavy concentrated loads. In this paper, it is shown that it is possible to use active control mechanisms to enhance the load-bearing capacity of the trusses. Under heavy loading, some elements of a truss might experience high stresses and show non-linear behavior, resulting in large deformations in the truss. Under such a condition, some elements of the truss might damage which can lead to the collapse of the truss. Application of control forces on some of the degrees of freedom of the truss can render help the truss tolerate larger forces before its collapse. A neural network can then be trained to learn the relationship between the...
Fast correlation attacks on the summation generator
, Article Journal of Cryptology ; Volume 13, Issue 2 , 2000 , Pages 245-262 ; 09332790 (ISSN) ; Salmasizadeh, M ; Dawson, E ; Sharif University of Technology
Springer New York
2000
Abstract
Abstract. The linear sequential circuit approximation method for combiners with memory is used to find mutually correlated linear transforms of the input and output sequences in the well-known summation generator with any number of inputs. It is shown that the determined correlation coefficient is large enough for applying a fast correlation attack to the output sequence to reconstruct the initial states of the input linear feedback shift registers. The proposed attack is based on iterative probabilistic decoding and appropriately generated low-weight parity-checks. The required output sequence length and the computational complexity are both derived. Successful experimental results for the...
Stabilizing control structures: An optimization framework
, Article IEEE Transactions on Automatic Control ; Volume 67, Issue 7 , 2022 , Pages 3738-3745 ; 00189286 (ISSN) ; Babazadeh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This article presents a new optimization-based approach to determine the class of stabilizing control structures with the necessary set of feedback links for interconnected systems. The proposed approach relies on a graph-theoretic interpretation and its equivalence in terms of binary linear programs (BLPs). To carry out the primary goal, first, the stabilizability of a linear time-invariant (LTI) system under the decentralized control structure is presented in terms of a BLP. Next, two graph-based criteria are proposed to characterize stabilizing control structures with the required feedback links. Finally, all possible stabilizing control structures with the necessary feedback links are...
Computational analysis of heat and mass transfer in a micropolar fluid flow through a porous medium between permeable channel walls
, Article International Journal of Nonlinear Sciences and Numerical Simulation ; Volume 23, Issue 5 , 2022 , Pages 761-775 ; 15651339 (ISSN) ; Ashraf, M ; Ali, K ; Nisar, K. S ; Sharif University of Technology
De Gruyter Open Ltd
2022
Abstract
The present work numerically investigates the mass and heat transport flow of micropolar fluid in a channel having permeable walls. The appropriate boundary layer approximations are used to convert the system of flow model equations in ODEs, which are then numerically treated with the quasi-linearization method along with finite difference discretization. This technique creates an efficient way to solve the complex dynamical system of equations. A numerical data comparison is presented which assures the accuracy of our code. The outcomes of various problem parameters are portrayed via the graphs and tables. The concentration and temperature accelerate with the impacts of the Peclet numbers...
Quasi-Linearization analysis for entropy generation in mhd mixed-convection flow of casson nanofluid over nonlinear stretching sheet with arrhenius activation energy
, Article Symmetry ; Volume 14, Issue 9 , 2022 ; 20738994 (ISSN) ; Faridi, A. A ; Ahmad, S ; Jamshed, W ; Hussain, S. M ; Tag-Eldin, E. S. M ; Sharif University of Technology
MDPI
2022
Abstract
Thermal performance of magnetically driven Casson nanofluid over a nonlinear stretching sheet under the influence of entropy, activation energy and convective boundary conditions was analyzed numerically, employing the quasi-linearization method (QLM). The collective behavior of thermophoretic diffusion and Brownian motion along with special effects of viscous dissipation, thermal radiation, heat generation and joule heating are considered in the energy equation for the flow problem. The addition of nanoparticles helps to stabilize the flowing of a nanofluid and maintain the symmetry of the flowing structure. The governing highly nonlinear coupled differential equations of velocity,...
Mixed integer linear programming problem for personnel multi-day shift scheduling: A case study in an Iran hospital
, Article Alexandria Engineering Journal ; Volume 61, Issue 1 , 2022 , Pages 419-426 ; 11100168 (ISSN) ; Sharifnia, S. M. E ; Cárdenas Barrón, L. E ; Sharif University of Technology
Elsevier B.V
2022
Abstract
The application of mathematical and systematic models and approaches to health is on the rise. In this study, a mixed-integer linear programming problem with cost (staff payroll) objective function is proposed to determine homogeneous personnel shift scheduling so that the constraints of the number of personnel per shift are met. The purpose of this study is to optimize the scheduling of personnel with the same skills to minimize variable hospital costs. In a hospital, homogeneous personnel might be skilled nurses who can work in the same departments or service staff of the departments. First, a mathematical model is proposed for scheduling as a linear problem and solved using Lingo...
On the assignability of LTI systems with arbitrary control structures
, Article International Journal of Control ; Volume 95, Issue 8 , 2022 , Pages 2098-2111 ; 00207179 (ISSN) ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
In this paper, the assignability of linear time-invariant (LTI) systems with respect to arbitrary control structures is addressed. It is well established that the closed-loop spectrum of an LTI system with an arbitrary control structure is confined to the set containing the fixed-modes of the system with respect to that control structure. However, the assignment of the closed-loop spectrum is not merely limited by the existence of fixed-modes in practical scenarios. The pole assignment may require excessive control effort or even become infeasible due to the presence of small perturbations in the system dynamics. To offer more insights in such more realistic scenarios, a continuous measure...
A new pseudolinear solution to bearing-only tracking
, Article IEEE National Radar Conference - Proceedings ; 2013 ; 10975659 (ISSN) ; 9781467357920 (ISBN) ; Khalili, M. M ; Norouzi, Y ; Nayebi, M. M ; Sharif University of Technology
2013
Abstract
The main focus of this paper is on the estimation of target motion parameters using bearing measurements. Here, based on a linearization of measurements, a recursive least squares (RLS) solution is developed. The performance of the proposed method is compared to PLE which uses the same approach in measurement linearization. Simulation results show the excellence of the proposed method over the PLE, and RLS results are in vicinity of the CRLB
Improved linear cryptanalysis of reduced-round SIMON-32 and SIMON-48
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 6 December 2015 through 9 December 2015 ; Volume 9462 , December , 2015 , Pages 153-179 ; 03029743 (ISSN); 9783319266169 (ISBN) ; Alizadeh, J ; Alkhzaimi, H. A ; Aref, M. R ; Bagheri, N ; Gauravaram, P ; Biryukov A ; Goyal V ; Sharif University of Technology
Springer Verlag
2015
Abstract
In this paper we analyse two variants of SIMON family of light-weight block ciphers against variants of linear cryptanalysis and present the best linear cryptanalytic results on these variants of reducedround SIMON to date. We propose a time-memory trade-off method that finds differential/ linear trails for any permutation allowing low Hamming weight differential/ linear trails. Our method combines low Hamming weight trails found by the correlation matrix representing the target permutation with heavy Hamming weight trails found using a Mixed Integer Programming model representing the target differential/linear trail. Our method enables us to find a 17-round linear approximation for SIMON-48...
Partial integrity of unstable LTI systems
, Article 24th Mediterranean Conference on Control and Automation, 21 June 2016 through 24 June 2016 ; 2016 , Pages 1302-1306 ; 9781467383455 (ISBN) ; Nobakhti, A ; Babazadeh, M ; MCA ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
Abstract
This paper considers the Integral Stabilizability (IS) and partial integrity of Linear Time Invariant (LTI) systems with an unstable sub-system. The main contribution of the paper is to show that if the unstable sub-system can be stabilized by means of output feedback, then one obtains an integrity condition which is actually equivalent to that of open-loop stable systems, with two additional assumptions. This means the condition may be evaluated solely on the basis of plant information and does not rely on the knowledge of the values of the controller parameters
Visibility extension via mirror-edges to cover invisible segments
, Article Theoretical Computer Science ; Volume 789 , 2019 , Pages 22-33 ; 03043975 (ISSN) ; Ghodsi, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Given a simple polygon P with n vertices, the visibility polygon (VP) of a point q, or a segment pq‾ inside P can be computed in linear time. We propose a linear time algorithm to extend the VP of a viewer (point or segment), by converting some edges of P into mirrors, such that a given non-visible segment uw‾ can also be seen from the viewer. Various definitions for the visibility of a segment, such as weak, strong, or complete visibility are considered. Our algorithm finds every edge that, when converted to a mirror, makes uw‾ visible to our viewer. We find out exactly which interval of uw‾ becomes visible, by every edge middling as a mirror, all in linear time. In other words, in this...