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#### On linear transformations preserving at least one eigenvalue

, Article Proceedings of the American Mathematical Society ; Volume 132, Issue 6 , 2004 , Pages 1621-1625 ; 00029939 (ISSN) ; Aryapoor, M ; Sharif University of Technology
2004

Abstract

Let F be an algebraically closed field and T: Mn(F) → Mn(F) be a linear transformation. In this paper we show that if T preserves at least one eigenvalue of each matrix, then T preserves all eigenvalues of each matrix. Moreover, for any infinite field F (not necessarily algebraically closed) we prove that if T: Mn(F) → M n(F) is a linear transformation and for any A ∈ Mn(F) with at least an eigenvalue in F, A and T(A) have at least one common eigenvalue in F, then T preserves the characteristic polynomial

#### Fuzzy linear programming with grades of satisfaction in constraints

, Article Iranian Journal of Fuzzy Systems ; Volume 6, Issue 3 , 2009 , Pages 17-35 ; 17350654 (ISSN) ; Maali, Y ; Mahdavi Amiri, N ; Sharif University of Technology
Abstract

We present a new model and a new approach for solving fuzzy linear programming (FLP) problems with various utilities for the satisfaction of the fuzzy constraints. The model, constructed as a multi-objective linear programming problem, provides flexibility for the decision maker (DM), and allows for the assignment of distinct weights to the constraints and the objective function. The desired solution is obtained by solving a crisp problem controlled by a parameter. We establish the validity of the proposed model and study the effect of the control parameter on the solution. We also illustrate the efficiency of the model and present three algorithms for solving the FLP problem, the first of...

#### Tits alternative for maximal subgroups of skew linear groups

, Article Communications in Algebra ; Volume 38, Issue 6 , Jun , 2010 , Pages 2354-2363 ; 00927872 (ISSN) ; Mahdavi Hezavehi, M ; Sharif University of Technology
2010

Abstract

Let D be a noncommutative finite dimensional F-central division algebra, and let N be a normal subgroup of GLn(D) with n≥1. Given a maximal subgroup M of N, it is proved that either M contains a noncyclic free subgroup, or there exists an abelian subgroup A and a finite family {Ki}1 r of fields properly containing F with Ki* ∩ N ⊃ M for all 1 ≤ i ≤ r such that M/A is finite if Char F = 0 and M/A is locally finite if Char F = p > 0, where A ⊆ K1* ×...× Kr*

#### Ag Raman modes and ion-position dependence of the electronic structures of Y Ba2 Cu3 O7 and Y Ba2 Cu4 O8 from first principles

, Article Physical Review B - Condensed Matter and Materials Physics ; Volume 76, Issue 5 , 2007 ; 10980121 (ISSN) ; Mossalla, B ; Akhavan, M ; Sharif University of Technology
2007

Abstract

Calculations of the frozen phonon for Ag Raman modes of the superconducting Y Ba2 Cu3 O7 and Y Ba2 Cu4 O8 systems have been carried out using the pseudopotential density functional theory in the local density approximation employing the VASP code. The eigenvalues and eigenvectors of the Ag Raman modes for the two systems have been calculated and compared with other experimental and computational studies. Electronic band structure and total density of states have been calculated for all the bare Ag modes for both systems. By calculating the changes in the bands intersecting the Fermi energy by ionic displacements, the ionic dependence of the electronic band structure in each of the Ag Raman...

#### On maximal and minimal linear matching property

, Article Algebra and Discrete Mathematics ; Volume 15, Issue 2 , 2013 , Pages 174-178 ; 17263255 (ISSN) ; Darafsheh, M. R ; Sharif University of Technology
2013

Abstract

The matching basis in field extentions is in-troduced by S. Eliahou and C. Lecouvey in [2]. In this paper we define the minimal and maximal linear matching property for field extensions and prove that if K is not algebraically closed, then K has minimal linear matching property. In this paper we will prove that algebraic number fields have maximal linear matching property. We also give a shorter proof of a result established in [6] on the fundamental theorem of algebra

#### Extended haessler heuristic algorithm for cutting stock problem: a case study in film industry

, Article Australian Journal of Basic and Applied Sciences ; Volume 3, Issue 4 , 2009 , Pages 3944-3953 ; 19918178 (ISSN) ; Mohammadi, A ; Sharif University of Technology
2009

Abstract

The cutting stock problem is an important problem in the field of combinational optimization. In classic versions of this problem, the aim is to find a solution for cutting some equal-width mother rolls into smaller parts with given width so that the amount of trim-loss become as small as possible. There are plenty of works which addressed the classic cutting stock problem. However in real world applications there are usually some constraints which make the problem different form classical version and make it harder to solve. In this paper we investigate a special cutting stock problem in film industry and show that it can not be solved by using previous methods. We propose a new hybrid...

#### Piecewise affine system modeling and control of PWM converters

, Article Journal of Circuits, Systems and Computers ; Volume 16, Issue 1 , 2007 , Pages 113-128 ; 02181266 (ISSN) ; Molaei, B ; Sharif University of Technology
2007

Abstract

The averaged switch modeling approach is a powerful method for representing the behavior of a wide variety of converters through equivalent circuits. The model is not linear and it is common to perform a small signal linearization about an operating point and design a linear controller. Models obtained with such method involve considerable approximation and produce results that are limited for high performance controller designs. In this paper a piecewise affine approximation technique is introduced for modeling PWM converters. This model is much more precise in predicting the dynamic response of averaged nonlinear model comparing the linear model. This paper also presents a piecewise linear...

#### Chaos synchronization in a class of chaotic systems using Kalman filter and feedback linearization methods

, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Alasty, A ; Sharif University of Technology
American Society of Mechanical Engineers
2006

Abstract

In this paper a combination of Kalman filter and feedback linearization methods is used to present a controller-identifier system for synchronizing two different chaotic systems. The drive system has some unknown parameters which are supposed to have linear form within its dynamic equation. An identifier based on Kalman filter approach is designed to estimate the unknown parameters of the drive system, and simultaneously a feedback linearizing controller is used to synchronize the chaotic behavior of the response system with the drive chaotic system. The method proposed in this paper is applied to the Lure' and the Genesio dynamic systems as the drive and response chaotic systems. The...

#### A mathematical-programming approach to fuzzy linear regression analysis

, Article Applied Mathematics and Computation ; Volume 155, Issue 3 , 2004 , Pages 873-881 ; 00963003 (ISSN) ; Nasrabadi, E ; Sharif University of Technology
2004

Abstract

Most of previous studies on fuzzy regression analysis have a common characteristic of increasing spreads for the estimated fuzzy responses as the independent variable increases its magnitude, which is not suitable for general cases. In this paper, fuzzy linear regression models with fuzzy/crisp output, fuzzy/crisp input are considered, and an estimated method along with a mathematical-programming-based approach is proposed. The advantages of the proposed approach are simplicity in programming and computation, and minimum difference of total spread between observed and estimated values. © 2003 Elsevier Inc. All rights reserved

#### How to extend visibility polygons by mirrors to cover invisible segments

, Article 11th International Conference and Workshops on Algorithms and Computation, WALCOM 2017, 29 March 2017 through 31 March 2017 ; Volume 10167 LNCS , 2017 , Pages 42-53 ; 03029743 (ISSN); 9783319539249 (ISBN) ; Ghodsi, M ; Sharif University of Technology
Springer Verlag
2017

Abstract

Given a simple polygon P with n vertices, the visibility polygon (V P) of a point q (V P(q)), or a segment (formula present) (V P(pq)) inside P can be computed in linear time. We propose a linear time algorithm to extend V P of a viewer (point or segment), by converting some edges of P into mirrors, such that a given non-visible segment (formula present) 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 such that, when converted to a mirror, makes (formula present) visible to our viewer. We find out exactly which interval of (formula present) becomes visible, by...

#### Tunable delay line based on Fourier-transformation and linear phase modulation with high time-bandwidth product

, Article Photonische Netze - 13. ITG-Fachtagung 2020 ; 2020 , Pages 229-231 ; Preubler, S ; Jamshidi, K ; Akbari, M ; Schneider, T ; Sharif University of Technology
VDE Verlag GmbH
2020

Abstract

We recruit basic properties of Fourier transformation to realize an electrically tunable delay line and increase the delay by creating a loop in the structure. The proposed method has been experimentally tested and verified for up to 5 roundtrips. The relative delay/advancement was increased up to 5 times compared to the original setup while preserving the original setup's advantages. © VDE VERLAG GMBH

#### Duality in fuzzy number linear programming by use of a certain linear ranking function

, Article Applied Mathematics and Computation ; Volume 180, Issue 1 , 2006 , Pages 206-216 ; 00963003 (ISSN) ; Nasseri, S. H ; Sharif University of Technology
2006

Abstract

We explore some duality properties in fuzzy number linear programming problems. By use of a linear ranking function we introduce the dual of fuzzy number linear programming primal problems. We then present several duality results. © 2006 Elsevier Inc. All rights reserved

#### Duality in fuzzy variable linear programming

, Article Wec 05: Fourth World Enformatika Conference, Istanbul, 24 June 2005 through 26 June 2005 ; Volume 6 , 2005 , Pages 115-117 ; 9759845857 (ISBN) ; Nasseri, S. H ; Sharif University of Technology
2005

Abstract

Recently, fuzzy variable linear programming problems have attracted some interests. We introduce the dual of fuzzy variable linear programming problem, and then deduce some important duality results. COPYRIGHT © ENFORMATIKA

#### A practical exact algorithm for the shortest loop design problem in a block layout

, Article International Journal of Production Research ; Volume 43, Issue 9 , 2005 , Pages 1879-1887 ; 00207543 (ISSN) ; Laporte, G ; Sharifyazdi, M ; Sharif University of Technology
2005

Abstract

The problem of determining a shortest loop incident to each cell of a block layout is considered. A compact formulation is developed for this problem and a relatively simple algorithm is presented. It is shown that instances containing up to 60 cells can be solved optimally by using a commercial integer linear programming solver embedded within an iterative scheme. © 2005 Taylor & Francis Group Ltd

#### Stabilizing controller design for quasi-resonant converters described by a class of piecewise linear models

, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Vol. 61, issue. 1 , 2014 , pp. 312-323 ; ISSN: 15498328 ; Tahami, F ; Sharif University of Technology
Abstract

This paper presents a stabilizing controller design method for quasi resonant (QR) converters described by a class of piecewise linear (PWL) models. The generalized state-space averaging technique (GSSA) is applied for the modeling and analysis of the half-wave zero current switching quasi-resonant (HW-ZCS-QR) buck converter. The nonlinear GSSA model of the converter is reconstructed using a piecewise linearizing technique. Subsequently, the piecewise linear models are combined together, to form a unified model, using a fuzzy modeling approach. The stability of the applied method has been investigated using Lyapunov method. Finally, a linear Hinfty; controller synthesis method is applied to...

#### Nonlinear tracking control of a microbeam displacement by electrostatic actuation

, Article World Academy of Science, Engineering and Technology ; Volume 79 , July , 2011 , Pages 232-236 ; ISSN: 2010376X ; Layeghi, H ; Salarieh, H ; Alasti, A ; Sharif University of Technology
Abstract

In this study tracking problem of tip of a micro cantilever, actuated by electrostatic, is investigated. Dynamic model of the system is a PDE. Using electrostatic actuation.introduced significant nonlinearity in dynamic model of the system. Control goals are achieved by means of backstepping for SI and feedback linearization for MI system. Performance of control system is inspected for some assumptions and simplifications. The results are in according to numerical simulations

#### A geometric approach for separating post non-linear mixtures

, Article European Signal Processing Conference, 3 September 2002 through 6 September 2002 ; Volume 2015-March , September , 2015 ; 22195491 (ISSN) ; Jutten, C ; Nayebi, K ; Sharif University of Technology
European Signal Processing Conference, EUSIPCO
2015

Abstract

A geometric method for separating PNL mixtures, for the case of 2 sources and 2 sensors, has been presented. The main idea is to find compensating nonlinearities to transform the scatter plot of observations to a parallelogram. It then results in a linear mixture which can be separated by any linear source separation algorithm. An indirect result of the paper is another separability proof of PNL mixtures of bounded sources for 2 sources and 2 sensors

#### A non-linear model for the classification of stored items in supply chain management

, Article Proceedings 2010 International Symposium on Information Technology - System Development and Application and Knowledge Society, ITSim'10, 15 June 2010 through 17 June 2010 ; Volume 3 , June , 2010 , Pages 1636-1641 ; 9781424467181 (ISBN) ; Bozorgi Rad, M. A ; Ishak Desa, M ; Behnam, S ; Lessanibahri, S ; IEEE ; Sharif University of Technology
2010

Abstract

With the significant role that warehouse plays in connection to suppliers, distributors, and clients, and considering the costliness of storage systems, efforts have focused on the reduction of procedural expenses. Among the most significant expenses, one involves the distance traveled by operators or S/R machinery for the selection of ordered items; the common solution to which has been through the classification of stored items. Previous articles have focused on linear solutions to the abovementioned problem, such as P-Median. This article shall focus on the problems arising from the said solution, and instead a non-linear method proposed. Further, a heuristic algorithm is produced for the...

#### Non-linear metric learning using pairwise similarity and dissimilarity constraints and the geometrical structure of data

, Article Pattern Recognition ; Volume 43, Issue 8 , August , 2010 , Pages 2982-2992 ; 00313203 (ISSN) ; Bagheri Shouraki, S ; Sharif University of Technology
2010

Abstract

The problem of clustering with side information has received much recent attention and metric learning has been considered as a powerful approach to this problem. Until now, various metric learning methods have been proposed for semi-supervised clustering. Although some of the existing methods can use both positive (must-link) and negative (cannot-link) constraints, they are usually limited to learning a linear transformation (i.e., finding a global Mahalanobis metric). In this paper, we propose a framework for learning linear and non-linear transformations efficiently. We use both positive and negative constraints and also the intrinsic topological structure of data. We formulate our metric...