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41.
Le Quang Thuy Bui Thi Thanh Nguyen Thi Toan 《Journal of Optimization Theory and Applications》2017,173(2):421-442
Motivated by our recent works on optimality conditions in discrete optimal control problems under a nonconvex cost function, in this paper, we study second-order necessary and sufficient optimality conditions for a discrete optimal control problem with a nonconvex cost function and state-control constraints. By establishing an abstract result on second-order optimality conditions for a mathematical programming problem, we derive second-order necessary and sufficient optimality conditions for a discrete optimal control problem. Using a common critical cone for both the second-order necessary and sufficient optimality conditions, we obtain “no-gap” between second-order optimality conditions. 相似文献
42.
We consider energy estimates for second order homogeneous hyperbolic equations with time dependent coefficients. The property
of energy conservation, which holds in the case of constant coefficients, does not hold in general for variable coefficients;
in fact, the energy can be unbounded as t → ∞ in this case. The conditions to the coefficients for the generalized energy conservation (GEC), which is an equivalence
of the energy uniformly with respect to time, has been studied precisely for wave type equations, that is, only the propagation
speed is variable. However, it is not true that the same conditions to the coefficients conclude (GEC) for general homogeneous
hyperbolic equations. The main purpose of this paper is to give additional conditions to the coefficients which provide (GEC);
they will be called as C
k
-type Levi conditions due to the essentially same meaning of usual Levi condition for the well-posedness of weakly hyperbolic
equations. 相似文献
43.
Nguyen HT Tran HQ Nguyen TT Chau VM Bui KA Pham QL Nguyen MC Kim YH 《Chemical & pharmaceutical bulletin》2011,59(11):1417-1420
Ten oleanane-type saponins (1-10), including three new compounds, namely bifinosides A-C (1-3), were isolated from the roots of Panax bipinnatifidus SEEM. Their structures were elucidated on the basis of chemical and spectroscopic methods. 相似文献
44.
Han KN Li CA Bui MP Pham XH Seong GH 《Chemical communications (Cambridge, England)》2011,47(3):938-940
We controlled the morphologies of zinc oxide (ZnO) nanostructures on single-walled carbon nanotube electrodes by an electrochemical deposition method and investigated the dependence of the electrocatalytic characteristics toward hydrazine on the different morphologies. ZnO nanorods provided high electrocatalytic activity with unique electrochemical behaviours, associated with the H(+) ion generated by the electro-oxidation of hydrazine. 相似文献
45.
K. Doan Quoc T. Bui Dinh V. Cao Long W. Leoński 《The European physical journal. Special topics》2013,222(9):2241-2245
In this paper, using the idea introduced in (K. Wódkiewicz, Noise in strong laser-atom interaction, Proceedings of the VI International School of Coherent Optics, Ustron, Poland, September (1985) 19–26) and developed in (Cao Long Van, Stochastic Models of Isolated Collisions: Applications to Optical Phenomena, paper presented in LAMP Conference’89, Trieste, Italy (1989) II) we consider the influence of collisional fluctuations on the Mollow spectra of resonance fluorescence (RF). The fluctuations are taken into account by a simple shift of the constant detuning, involved in a set of optical Bloch equations by collision frequency noise which is modelled by a two-step random telegraph signal (RTS). We consider in detail the Mollow spectra for RF in the case of an arbitrary detuning of the laser frequency, where the emitter is a member of a statistical ensemble in thermodynamic equilibrium with the buffer gas at temperature T which is treated as a colored environment, and velocity v is distributed with the Maxwell-Boltzmann density. 相似文献
46.
T. Bui Dinh K. Doan Quoc V. Cao Long K. Dinh Xuan 《The European physical journal. Special topics》2013,222(9):2233-2239
We discuss the propagation of a short laser pulse in an auto- ionizing (AI) medium with degenerate double Fano model. By solving numerically the coupled equations for atoms and fields we show that by the proper choice of Fano parameters involved in the problem (contrary to the case considered in (E. Paspalakis, N. J. Kylstra, and P. L. Knight, Phys. Rev. A60 (1999)) we have now two Fano asymmetry parameters) one can eliminate almost completely the absorption in the pulse propagation. It means that we have the transparency in the medium. From the connection between population trapping in short pulsed laser field and transparency in the propagation of the laser pulse which has been fixed by Paspalakis et al., Phys. Rev. A60 (1999) we conclude that this proper choice leads to the presence of the population trapping (or the existence of the “dark” states) in the atomic system. Moreover, instead of one value of the laser detuning for which the dark states exist in the case of one AI level, we find numerically two such values in the case of two AI levels. 相似文献
47.
48.
For almost twenty years, the Ford-Johnson algorithm for sortingt items using comparisons was believed to be optimal. Recently, Manacher was able to show that the Ford-Johnson algorithm is not optimal for certain ranges of values oft. In this paper, we present some new algorithms which achieve much stronger results compared to Manacher's algorithms. 相似文献
49.
50.