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61.
This Letter deals with the problem of designing time-delayed feedback controllers (TDFCs) to stabilize unstable equilibrium points and periodic orbits for a class of continuous time-delayed chaotic systems. Harmonic balance approach is used to select the appropriate controller parameters: delay time and feedback gain. The established theoretical results are illustrated via a case study of the well-known Logistic model. 相似文献
62.
Passivity analysis for uncertain neural networks with discrete and distributed time-varying delays 总被引:1,自引:0,他引:1
In this Letter, the passivity problem of uncertain neural networks with discrete and distributed time-varying delays is investigated. New delay-dependent conditions for this problem are obtained by using a novel Lyapunov functional together with the linear matrix inequality (LMI) approach. Numerical examples are given to show the effectiveness of our theoretical results. 相似文献
63.
Yan Liu 《Physics letters. A》2009,373(41):3741-3742
In a previous work [Z.D. Wang, Y.R. Liu, L. Yu, X.H. Liu, Phys. Lett. A 356 (2006) 346] an exponential stability analysis for a class of Markovian jumping neural networks (MJNNs) was presented. In this Letter we employ the same technique to extend the results for MJNNs with time-varying delays and mode estimation, appropriate for active fault-tolerant control systems. 相似文献
64.
K. Ragavendran D. Sherwood D. Vasudevan Bosco Emmanuel 《Physica B: Condensed Matter》2009,404(16):2166-2171
Two batches of poly-crystalline lithium manganate were prepared by a fuel assisted solution combustion method. LiMn2O4(S) was prepared using starch as the fuel and LiMn2O4(P) was prepared using poly vinyl alcohol (PVA) as the fuel. XRD studies indicated a significant and consistent shift in the 2θ values of all the hkl peaks to higher values in LiMn2O4(P) compared to LiMn2O4(S) indicating a lattice contraction in the former. TG/DTA studies indicated a higher formation temperature (∼25 °C higher) for LiMn2O4(P). The higher formation temperature most likely promotes the oxidation of some Mn3+ to Mn4+ with a lower ionic radius causing a lattice contraction. This hypothesis is confirmed through XPS studies which indicated the presence of a higher fraction of Mn4+ in LiMn2O4(P) than that present in LiMn2O4(S). A crystal shape algorithm was used to generate the crystal habits of lithium manganate from their XRD data leading to an understanding on the exposed hkl planes in these materials. From the atomic arrangement on the exposed hkl planes it is predicted that LiMn2O4(P) would be less prone to manganese dissolution and hence would possess a higher cycle life when compared to LiMn2O4(S). 相似文献
65.
Phase relations and equation of state (EOS) of natural cinnabar (α-HgS) are investigated by high-pressure and high-temperature synchrotron x-ray powder diffraction. The unambiguous cinnabar-rocksalt structure phase boundaries are determined to be PI (GPa)=15.54- 0.014T(℃) and Pupper(GPa)= 23.84- 0.014T(℃) at 300-623K. With K1 fixed at 4, we obtain K0 = 37(4) GPa, (aK/aT)p= -0.025(2) GPaK-1, and α0 = 3.79(20) × 10-5 K-1 for the cinnabar phase of α-HgS. The (aK/aT)p and α0 of cinnabar phase are obtained for the first time. A nearly isotropic compression of cinnabar phase is observed by linear regressions. 相似文献
66.
First-Principles Study of Structural Stabilities, Electronic and Optical Properties of SrF2 under High Pressure 下载免费PDF全文
An investigation of structural stabilities, electronic and optical properties of SrF2 under high pressure is conducted using a first-principles calculation based on density functional theory (DFT) with the plane wave basis set as implemented in the CASTEP code. Our results predict that the second high-pressure phase of SrF2 is of a Ni2In- type structure, and demonstrate that the sequence of the pressure-induced phase transition of SrF2 is the fluorite structure (Fm3m) to the PbC12-type structure (Pnma), and to the Ni2In-type phase (P63/mmc). The first and second phase transition pressures are 5. 77 and 45.58 GPa, respectively. The energy gap increases initially with pressure in the Fm3m, and begins to decrease in the Pnma phases at 30 GPa. The band gap overlap metallization does not occur up to 210 GPa. The pressure effect on the optical properties is discussed. 相似文献
67.
Linh Mai Van-Su Pham Giwan Yoon 《Applied Physics A: Materials Science & Processing》2009,95(3):667-671
In this paper, we studied ZnO-based film bulk acoustic resonator (FBAR) device fabricated on a specially designed multilayered
Bragg reflector part. Very thin chromium adhesion layers (0.03 μm thick) were additionally deposited to improve the quality
of the Bragg reflector and some thermal treatments were performed to improve the resonant characteristics of the FBAR device.
At the operating frequency of ∼2.7 GHz, excellent resonant characteristics were observed in terms of return loss and quality
factor, and effective electromechanical coupling coefficient. 相似文献
68.
We calculate the one-photon loop radiative corrections to virtual pion Compton scattering
→
, that subprocess which determines in the one-photon exchange approximation the pion-nucleus bremsstrahlung reaction
Z →
Z
. Ultraviolet and infrared divergencies of the loop integrals are both treated by dimensional regularization. Analytical
expressions for the O() corrections to the virtual Compton scattering amplitudes, A(s, u, Q) and B(s, u, Q) , are derived with their full dependence on the (small) photon virtuality Q from 9 classes of contributing one-loop diagrams. Infrared finiteness of these virtual radiative corrections is achieved
(in the standard way) by including soft photon radiation below an energy cut-off . In the region of low
center-of-mass energies, where the pion-nucleus bremsstrahlung process is used to extract the pion electric and magnetic
polarizabilities, we find radiative corrections up to about -3% for = 5 MeV. Furthermore, we extend our calculation of the radiative corrections to virtual pion Compton scattering
→
by including the leading pion-structure effect in the form of the polarizability difference - . Our analytical results are particularly relevant for analyzing the data of the COMPASS experiment at CERN which aims at
measuring the pion electric and magnetic polarizabilities with high statistics using the Primakoff effect. 相似文献
69.
N. Stepp T. D. Frank 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(2):251-257
Synchronization has been shown to be a valuable concept in the field of nonlinear dynamics and dynamical systems in general.
Deviation from perfect synchronization results from an interplay of deterministic coupling forces and stochastic fluctuating
forces. When the exact details of these two sources of variance are unknown, it becomes useful to estimate them directly from
data. To this end, we develop a data analysis method for estimating parameters associated with these deterministic and stochastic
components. The method relies on separating their respective contributions to synchronization error. We focus on the case
where a slave system synchronizes with the future of a master system, so-called anticipating synchronization. 相似文献
70.
A Green function formalism is applied to study the dielectric function spectra and the small polaron hopping conduction in organic molecular crystals. In the calculations, the electron-phonon interaction is considered within the Hartree-Fock approximation, and the temperature effect is taken into account. Our theoretical approach is based on the polar electron-phonon interaction (Fröhlich type) to characterize the non-degenerate polaron gas, with the assumption of the electronic hopping between the first-neighbor. 相似文献