基于平稳小波和相空间重构的激光混沌预测

提出了一种激光混沌时间序列预测算法.该算法通过平稳小波分解，将原始数据序列分解为与原序列等长的尺度系数和小波系数，利用坐标延迟理论，重建各级尺度系数和各级小波系数的相空间,再根据混沌吸引子的稳定性和分形性,在相空间中对尺度系数和小波系数进行预测,进而通过平稳小波重构算法,实现了时间序列的非线性预测.该算法对数据可以进行更平滑的处理，比无小波算法预测的时间范围更长.通过仿真试验说明，原始时间数据序列被成功的重建，说明算法能够有效的对非线性动态系统的时间序列进行建模和预测.     

Design and synthesis of novel ionic liquid/liquid crystals (ILCs) with axial chirality

As the first examples of axially chiral ionic liquids, new pyridinium salts having a 1,3-dioxan ring in their central core were synthesized. Enantioselective dehydrohalogenation using chiral alkoxides provided a simple and practical approach for their synthesis. Some structures exhibit both low melting point and liquid crystalline behaviour.     

First-order phase transitions: equivalence between bimodalities and the Yang–Lee theorem

First-order phase transitions in finite systems can be defined through the bimodality of the distribution of the order parameter. This definition is equivalent to the one based on the inverted curvature of the thermodynamic potential. Moreover we show that it is in a one-to-one correspondence with the Yang–Lee theorem in the thermodynamic limit. Bimodality is a necessary and sufficient condition for zeroes of the partition sum in the control intensive variable complex plane to be distributed on a line perpendicular to the real axis with a uniform density, scaling like the number of particles.     

Speckle interferometry for measurement of continuous deformations

Improvements of a method for measurement of continuous displacements and deformations with digital phase shifting speckle pattern interferometry are presented. The method is based on an algorithm that, with the knowledge of the initial phase, only needs one image at a time to evaluate continuos phase changes due to object deformations. In the improved method, the initial random phase of the speckle pattern is evaluated using a number of phase-shifted images before the deformation under study. This is used for increasing the accuracy of the initial phase estimation and reducing influences from image noise and other measurement disturbances. The phase-shifted speckle patterns are used as references for comparison with the speckle patterns of the deformed object, thereby increasing the reliability and accuracy of the phase estimations of the deformed patterns. The technique can be used for measuring deformations such as transients and other dynamic events, heat expansion as well as other phenomena where it is difficult to accomplish phase shifting during deformation.     

Electron paramagnetic resonance investigation of K3H(SO4)2 proton conductor doped with Cr ion

The proton arrangement around SO₄ units in K₃H(SO₄)₂ (KHS) was studied in detail by X-band CW EPR spectra of CrO₄³⁻ paramagnetic centre incorporated into KHS during the crystal growth process. The EPR data prove the theoretical model of coherent motion of protons and SO₄ units at the fast-proton conducting phase proposed by Ito and Kamimura.     

A nonlinear superposition principle and multibump solutions of periodic Schrödinger equations

In an abstract setting we prove a nonlinear superposition principle for zeros of equivariant vector fields that are asymptotically additive in a well-defined sense. This result is used to obtain multibump solutions for two basic types of periodic stationary Schrödinger equations with superlinear nonlinearity. The nonlinear term may be of convolution type. If the superquadratic term in the energy functional is convex, our results also apply in certain cases if 0 is in a gap of the spectrum of the Schrödinger operator.     

The spin-

We study the effect of a nearby phase-conjugate mirror (PCM) on the gap soliton of a Kerr non-linear periodic structure. We show that phase conjugation of the gap soliton (in the sense of replication of the amplitude profile in the reverse direction) is possible under the condition of PCM reflectivity approaching unity. This is in contrast with the results for linear structures, where the wave profiles can be conjugated for arbitrary values of the PCM reflectivity. The sensitivity of the conjugation of the gap solitons to PCM reflectivity is ascribed to the fine balance of non-linearity with dispersion, necessary for their existence.     

Phase conjugation of gap solitons: A numerical study

We study the effect of a nearby phase-conjugate mirror (PCM) on the gap soliton of a Kerr non-linear periodic structure. We show that phase conjugation of the gap soliton (in the sense of replication of the amplitude profile in the reverse direction) is possible under the condition of PCM reflectivity approaching unity. This is in contrast with the results for linear structures, where the wave profiles can be conjugated for arbitrary values of the PCM reflectivity. The sensitivity of the conjugation of the gap solitons to PCM reflectivity is ascribed to the fine balance of non-linearity with dispersion, necessary for their existence.     

Eu:Fe:LiNbO3晶体非简并四波混频的研究

用波长为623.8nm的He-Ne激光作信号光和一束泵浦光,用波长为488.0nm的Ar⁺激光作另一束泵浦光,在Eu:Fe:LiNbO₃晶体中实现了非简并四波混频,获得了波长为488.0nm的变频相位共轭光,同时还产生了波长为632.8nm的同频相位共扼光。本文对上述实验结果进行了定性分析。     

Une modélisation thermomécanique unidimensionnelle de la propagation d'un front de changement de phase dans un monocristal d'AMFA one-dimensional thermomechanical modeling of phase change front propagation in a SMA monocrystal

We propose a behavioral modeling that takes into account the thermomechanical couplings accompanying the phase transition in single-crystal CuZnAl samples. The goal of this model is to put forward the significant role played by the heat diffusion in the propagation mode of the phase change fronts. Numerical simulations showed the existence of such a phase change front and predicted the calorimetric and kinematic effects accompanying its propagation. In particular, an inversion of the propagation way during a creep test and caused by an increase of the room temperature was correctly simulated by the model. To cite this article: A. Chrysochoos et al., C. R. Mecanique 331 (2003).