Quynhon University

Thị Trấn Sơn Dương, Vietnam

Quynhon University

Thị Trấn Sơn Dương, Vietnam

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Thuan M.V.,Thainguyen University of science | Trinh H.,Deakin University | Huong D.C.,Quynhon University
International Journal of Systems Science | Year: 2016

In this paper, we address the problem of finding outer bound of forward reachable sets and inter-bound of backward reachable sets of switched systems with an interval time-varying delay and bounded disturbances. By constructing a flexible Lyapunov–Krasovskii functional combining with some recent refined integral-based inequalities, some sufficient conditions are derived for the existence of (1) the smallest possible outer bound of forwards reachable sets; and (2) the largest possible inter-bound of backward reachable sets. These conditions are delay dependent and in the form of linear matrix inequalities, which therefore can be efficiently solved by using existing convex algorithms. A constructive geometric design of switching laws is also presented. Two numerical examples with simulation results are provided to demonstrate the effectiveness of our results. © 2016 Informa UK Limited, trading as Taylor & Francis Group


Hung L.Q.,Quynhon University | Cuong L.A.,Vietnam National University, Hanoi
Proceedings - 2nd International Conference on Knowledge and Systems Engineering, KSE 2010 | Year: 2010

Parallel corpus is the valuable resource for some important applications of natural language processing such as statistical machine translation, dictionary construction, cross-language information retrieval. The Web is a huge resource of knowledge, which partly contains bilingual information in various kinds of web pages. It currently attracts many studies on building parallel corpora based on the Internet resource. However, obtaining a parallel corpus with high accuracy is still a challenge. This paper focuses on extracting parallel texts from bilingual web-sites of the English and Vietnamese language pair. We first propose a new way of designing content-based features, and then combining them with structural features under a framework of machine learning. In the experiment we obtain 88.2% of precision for the extracted parallel texts. © 2010 IEEE.


Nam P.T.,Quynhon University | Pathirana P.N.,Deakin University | Trinh H.,Deakin University
IET Control Theory and Applications | Year: 2016

In this study, the authors address a new problem of finding, with a pre-specified time, bounds of partial states of non-linear discrete systems with a time-varying delay. A novel computational method for deriving the smallest bounds is presented. The method is based on a new comparison principle, a new algorithm for finding the infimum of a fractal function, and linear programming. The effectiveness of our obtained results is illustrated through a numerical example. © 2016 The Institution of Engineering and Technology.


Nam P.,Quynhon University | Pathirana P.N.,Deakin University | Trinh H.,Deakin University
IET Control Theory and Applications | Year: 2015

This study considers linear systems with state/input time-varying delays and bounded disturbances. The authors study a new problem of designing a static output feedback controller which guarantees that the state vector of the closedloop system converges within a pre-specified polyhedron. Based on the Lyapunov-Krasovskii method combining with the free-weighting matrix technique, a new sufficient condition for the existence of a static output feedback controller is derived. The author's condition is expressed in terms of linear matrix inequalities with two parameters need to be tuned and therefore can be efficiently solved by using a two-dimensional search method combining with convex optimisation algorithms. To be able to obtain directly an output feedback control matrix from the derived condition, they propose an appropriate combination between a state transformation with a choice of a special form of the free-weighting matrices. The feasibility and effectiveness of the derived results are illustrated through five numerical examples. © The Institution of Engineering and Technology 2015.


Phan T.H.,University of Bonn | Phan T.H.,Quynhon University | Wandelt K.,University of Bonn | Wandelt K.,Wrocław University
Surface Science | Year: 2013

Combined Cyclic Voltammetry (CV) and in-situ Electrochemical Scanning Tunneling Microscopy (EC-STM) studies were employed to compare the self-assembly of redox-active 5,10,15,20-Tetrakis (4-trimethyl ammonium phenyl) porphyrin tetra (p-toluenesulfonate), abbreviated as [H 2TTMAPP] + 4 on Cu(100) and Cu(111) electrode surfaces in 10 mM HCl solution. Under these conditions, both surfaces are chloride pre-covered with a c(2 × 2) Cl- and cp×3 Cl-layer on Cu(100) and Cu(111), respectively. On both surfaces highly ordered [H 2TTMAPP] + 4 layers are spontaneously formed. The short range molecular arrangement is quadratic in nature on both surfaces which can be described by a 58×58 R23° unit cell on the c(2 × 2) Cl-Cu(100), and a (3 × 4) unit cell on the cp×3 Cl-Cu(111) substrate. Large scale domains are formed on both surfaces the orientation of which reflects the symmetry of the substrate, namely on Cu(100) [Cu(111)] equivalent domains are rotated by 90° [120°], respectively. Thus, the different symmetry of the respective substrate surface has an influence on the otherwise self-assembled organic molecules. © 2012 Elsevier B.V. All rights reserved.


Huong D.C.,Quynhon University | Trinh H.,Deakin University
Journal of the Franklin Institute | Year: 2016

This paper addresses the problem on how to systematically compute state transformations of a general class of time-delay systems with multiple time delays in the state and output vectors, and applications of these state transformations to state observer design. First, a forward state transformation problem is studied. For this, we present a two-stage coordinate transformation method to transform any given time-delay system into an observable canonical form where time delays appear in the input and output vectors, but not in the state vector. The significance of such a coordinate transformation is that a Luenberger-type state observer can be easily designed in the new coordinate system. Then, a backward state transformation problem is studied which allows us to reconstruct the original state vector of the system. Therefore, by using both the forward and the backward state transformations, state observers for time-delay systems can be systematically designed. Our approach based on the new state transformations enables the design of state observers of a more general class of time-delay systems than existing works in the literature. Conditions for the existence of the state transformations and an algorithm for computing them are provided in this paper. Numerical examples and simulation results are given to illustrate the effectiveness of our proposed design method. © 2016 The Franklin Institute.


Nam P.T.,Quynhon University | Pathirana P.N.,Deakin University
Automatica | Year: 2011

The problem of reachable set estimation of linear uncertain polytopic time-varying delay systems subject to bounded peak inputs is studied in this paper. The delays considered in this paper are assumed to be non-differentiable and vary within an interval where the lower and upper bounds are known. Based on the LyapunovKrasovskii method and delay decomposition technique, a sufficient condition for the existence of a ball that bounds the reachable set of the system is proposed in terms of matrix inequalities containing only one scalar which can be solved by using an one-dimensional search method and Matlab's LMI Toolbox and allow us to find the smallest radius. A numerical example is given to illustrate the effectiveness of the proposed result. © 2011 Elsevier Ltd. All rights reserved.


Nam P.T.,Deakin University | Nam P.T.,Quynhon University | Trinh H.M.,Deakin University | Pathirana P.N.,Deakin University
Automatica | Year: 2016

This paper presents a method to derive componentwise ultimate upper bounds and componentwise ultimate lower bounds for linear positive systems with time-varying delays and bounded disturbances. The disturbance vector is assumed to vary within a known interval whose lower bound may be different from zero. We first derive a sufficient condition for the existence of componentwise ultimate bounds. This condition is given in terms of the spectral radius of the system matrices which is easy to check and allows us to compute directly both the smallest componentwise ultimate upper bound and the largest componentwise ultimate lower bound. Then, by using the comparison method, we extend the obtained result to a class of nonlinear time-delay systems which has linear positive bounds. Two numerical examples are given to illustrate the effectiveness of the obtained results. © 2016 Elsevier Ltd


Ha Q.P.,University of Technology, Sydney | That N.D.,University of Technology, Sydney | That N.D.,Vietnam Maritime University | Nam P.T.,Quynhon University | Trinh H.,Deakin University
ISA Transactions | Year: 2014

This paper deals with the problem of partial state observer design for linear systems that are subject to time delays in the measured output as well as the control input. By choosing a set of appropriate augmented Lyapunov-Krasovskii functionals with a triple-integral term and using the information of both the delayed output and input, a novel approach to design a minimal-order observer is proposed to guarantee that the observer error is ε-convergent with an exponential rate. Existence conditions of such an observer are derived in terms of matrix inequalities for the cases with time delays in both the output and input and with output delay only. Constructive design algorithms are introduced. Numerical examples are provided to illustrate the design procedure, practicality and effectiveness of the proposed observer. © 2013 ISA.


Huong D.C.,Quynhon University | Trinh H.,Deakin University
IET Control Theory and Applications | Year: 2015

This study provides a systematic method for deriving state transformations of a class of time-delay systems with multiple output. The significance of this study is that such state transformations can be used to transform timedelay systems into new coordinates where all the time-delay terms in the system description are associated with the output and input only. Therefore, in the new coordinate system, a Luenberger-type state observer can be readily designed. Subsequently, of the three possible versions of the original state vector, namely, instantaneous, delayed, and a mixed of instantaneous and delayed, a state observer which estimates one of these versions can be obtained. This new finding allows the authors to design state observers for a wider class of time-delay systems. Conditions for the existence of such coordinate changes and an effective algorithm for computing them are provided in this study. A numerical example and simulation results are given to illustrate the simplicity and effectiveness of the proposed method. © The Institution of Engineering and Technology 2015.

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