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Qui Nhon, Vietnam

Phat V.N.,Institute of Mathematics | Nam P.T.,Quy Nhon University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

This Letter deals with the problem of exponential stability for a class of delayed Hopfield neural networks. Based on augmented parameter-dependent Lyapunov-Krasovskii functionals, new delay-dependent conditions for the global exponential stability are obtained for two cases of time-varying delays: the delays are differentiable and have an upper bound of the delay-derivatives, and the delays are bounded but not necessary to be differentiable. The conditions are presented in terms of linear matrix inequalities, which allow to compute simultaneously two bounds that characterize the exponential stability rate of the solution. Numerical examples are included to illustrate the effectiveness of our results. © 2010 Elsevier B.V. All rights reserved.


Trung N.T.,Quy Nhon University | Nguyen M.T.,Catholic University of Leuven
Chemical Physics Letters | Year: 2013

Interaction energies obtained using CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ computations including both ZPE and BSSE corrections range from -2.9 to -14.2 kJ mol-1. While formic acid forms the most stable complex with CO 2, formaldehyde yields the least stable complex. Lewis acid-base interaction such as C-Nâ";C(CO2), COâ""; C(CO2), which overcomes C-Hâ"";O blue-shifting hydrogen bond, plays a significant role in stabilizing most complexes. However, the strength of (HCOOH, CO2) is mainly determined by O-Hâ"";O red-shifting hydrogen bond. The C- Hâ"";O blue-shifting hydrogen bond is revealed upon complexation of CH3OH, HCHO, HCOOH, CH3COCH3 and HCOOCH3 with CO2. Remarkably, existence of weak hydrogen bonded C-Hâ"";O interaction is not found in the (CH 3OCH3, CO2) and (CH3NH2, CO2) pairs. © 2013 Elsevier B.V. All rights reserved.


Ngan V.T.,Catholic University of Leuven | Ngan V.T.,Quy Nhon University | Pierloot K.,Catholic University of Leuven | Nguyen M.T.,Catholic University of Leuven
Physical Chemistry Chemical Physics | Year: 2013

The electronic structure of Mn@Si14 + is determined using DFT and CASPT2/CASSCF(14,15) computations with large basis sets. The endohedrally Mn-doped Si cationic cluster has a D3h fullerene-like structure featuring a closed-shell singlet ground state with a singlet-triplet gap of ∼1 eV. A strong stabilizing interaction occurs between the 3d(Mn) and the 2D-shell(Si14) orbitals, and a large amount of charge is transferred from the Si14 cage to the Mn dopant. The 3d(Mn) orbitals are filled by encapsulation, and the magnetic moment of Mn is completely quenched. Full occupation of [2S, 2P, 2D] shell orbitals by 18 delocalized electrons confers the doped Mn@Si14 + cluster a spherically aromatic character. © 2013 the Owner Societies.


Van Ngai H.,Quy Nhon University
SIAM Journal on Optimization | Year: 2015

This paper is devoted to studying the Lipschitzian/Hölderian-type global error bound for systems of finitely many convex polynomial inequalities over a polyhedral constraint. First, for systems of this type, we show that under a suitable asymptotic qualification condition the Lipschitzian-type global error bound property is equivalent to the Abadie qualification condition; in particular, the Lipschitzian-type global error bound is satisfied under the Slater condition. Second, without regularity conditions, the Hölderian global error bound with an explicit exponent is investigated. © 2015 Society for Industrial and Applied Mathematics.


Thuan L.Q.,University of Groningen | Thuan L.Q.,Quy Nhon University | Camlibel M.K.,University of Groningen | Camlibel M.K.,Dogus University
IEEE Transactions on Automatic Control | Year: 2011

In the context of continuous piecewise affine dynamical systems, we study the Zeno behavior, i.e., infinite number of mode transitions in finite time interval, in this note. The main result reveals that piecewise affine dynamical systems do not exhibit Zeno behavior. A direct benefit of the main result is that one can apply smooth ordinary differential equations theory in a local manner for the analysis of piecewise affine systems. © 2010 IEEE.

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