Information transmission using a synchronous chaotic response with filtering in the communication channel

A principle is proposed for obtaining a chaotic synchronous response in a driven nonlinear oscillatory system under conditions where the signal of the driving chaotic system is filtered by the coupling channel. Music and speech signals are used to demonstrate the efficiency of applying this principle to transmit information through a channel having a limited frequency band. Pis’ma Zh. Tekh. Fiz. 25, 71–77 (August 26, 1999)     

Flux-gate magnetic field sensor based on yttrium iron garnet films for magnetocardiography investigations

Technical Physics Letters - A new type of f lux-gate vector magnetometer based on epitaxial yttrium iron garnet films has been developed and constructed for magnetocardiography (MCG)...     

Composition engineering of single crystalline films based on the multicomponent garnet compounds

The paper demonstrates our last achievement in development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped multicomponent garnets using the Liquid Phase Epitaxy (LPE) method. We report in this work the optimized content and excellent scintillation properties of SCF of Lu_3-xGd_xAl_5-yGa_yO₁₂, Lu_3-xTb_xAl_5-yGa_yO₁₂ and Tb_xGd_xAl_5-yGa_yO₁₂ garnet compounds grown by the LPE method from PbOB₂O₃ based melt-solution onto Gd₃Al_2.5Ga_2.5O₁₂ and YAG substrates.We also show that the Tb_1.5Gd_1.5Al_2.5Ga_2.5O₁₂:Ce SCF possess the highest light yield (LY) in comparison with all ever grown garnet SCF scintillators. Namely, the LY of these SCF exceeds by 3.8 and 1.85 times the LY values of the best samples of YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCF samples of the mentioned compounds show low thermoluminescence in the above room temperature range and relatively fast scintillation decay time t_1/e in the 180–200 ns range.     

基于双混沌系统伪随机比特发生器的研究

研究了基于双混沌系统伪随机比特发生器（CCS-PRBG）生成序列的密码学性质,证明了此二进制序列是i.i.d.序列。理论分析表明,CCS-PRBG可生成具有理想保密性的二进制混沌密码序列。     

Phototropic centers in lasers systems based on rare earth garnet crystals

The emission from Cr³⁺ ions at 730 nm is enhanced under the action of the second harmonic radiation of a neodymium laser, while the intensity of emission at 1.54 μm from Cr⁴⁺ ions in tetrahedral positions remains unchanged. This result casts doubt on the interpretation of absorption bands at 0.775–1.26 μm and the luminescence bands at 1.103–1.67 μm in the spectra of rare earth garnets, which have been previously assigned to electron transitions in Cr⁴⁺ ions occupying tetrahedral positions in the garnet structure.     

永磁同步电机系统、网络混沌振荡同步中断分析与控制

已有研究表明,电机在某些参数及工作条件下会出现混沌振荡行为。另一方面,现代工业生产过程中,经常需要多台电机协调同步运行。当前,国内外对电机系统、网络的混沌振荡同步分析与控制已有较多研究,但对电机系统、网络由于参数扰动引起同步中断的分析与控制研究尚属少见。为此,在传统的扩散耦合方式基础上,通过引入单向交叉耦合方式,研究了永磁同步电机(PMSM)系统、网络受到参数扰动后的振动特性。分析并证明了单向交叉耦合对PMSM系统、网络的参数扰动具有同步鲁棒性;并以3节点、4节点和一个多节点网络的PMSM系统验证,交叉耦合对多节点电机网络全局稳定同步的重要作用。研究结果表明,通过建立合适的单向交叉耦合方式,能够有效控制电机网络因参数扰动而引发的同步中断,使同步中断得以重新恢复。     

Small optical magnetic-field sensor that uses rare-Earth iron garnet films based on the faraday effect

Highly accurate optical magnetic-field probe sensors that use iron garnet films have been developed. New probe-type sensors were designed with a confocal optical system. A new garnet composition, Bi(0.98)Gd(0.92)La(0.03)Y(1.07)Fe(4.72)Ga(0.28)O(12), was found that shows high temperature stability for a sensitivity of less than 2.0% from -20 to +80 degrees C. The linearity error of the sensor output was within 1.0% for alternating magnetic fields from 0.3 to 42 mT. An optical current transformer that uses the proposed sensor has an ac linearity of 1.0% for input current up to nearly 300 A. The sensor realized high performance in actual use.     

基于混沌正交组合序列的M元码分多址水声通信

提出了M元能量检测器算法,该算法简单易实现,极大优化了M元码分多址系统接收机结构和解码运算量。同时,M元能量检测器具有抗载波相位跳变和抗水声信道多途干扰的能力。针对M元码分多址水声通信系统中所需扩频序列数量庞大、选码难度高的问题,提出了混沌正交组合序列,通过简单的迭代组合即可产生大量满足要求的扩频序列,而且同族的混沌正交组合序列间满足正交关系。海试试验成功实现了7个用户的M元码分多址水声通信试验(M=512),共采用了3 584条混沌正交组合序列,每个用户通信速率为70 bit.s-1,验证了算法的有效性,为网络化水声通信的应用提供了技术基础。     

Wideband chaotic microwave signal generation in a ring system with a nonlinear delay line on coupled ferromagnetic films

Various regimes of chaotic signal generation have been studied in an self-oscillating ring system with a wideband nonlinear delay line based on coupled ferromagnetic films, in which magnetostatic backward volume waves (MSBVWs) are excited. It is shown for the first time that the simultaneous excitation of two waves in the coupled films leads to the appearance of a falling part in the dynamic characteristic of the MSBVW delay line and the generation of a broadband chaotic signal with a continuous spectrum. Under certain conditions, the ring exhibits a regime of intermittency, in which broadband chaotic signals with both continuous and discrete spectra are generated.     

Intrinsic pinning of a ferromagnetic domain wall in yttrium iron garnet films with strong uniaxial anisotropy

Movements of individual domain walls in a ferromagnetic garnet were studied with angstrom resolution. The measurements reveal that domain walls can be locked between adjacent crystallographic planes and propagate by distinct steps matching the lattice periodicity.     

一类非线性混沌振动的主动隔振实验研究

本文以Duffing非线性振子为研究对象 ,应用主动隔振原理 ,设计了参数自调节的PID控制算法 ,对Duffing振子混沌振动进行了主动隔振数值仿真实验 ,实现了对混沌振动的良好隔振。仿真结果表明 :在混沌振动中应用主动隔振技术的有效性     

Basins of attraction for chaotic attractors in coupled systems with period doubling

This article studies basins of attraction for chaotic attractors and their evolution when the attractors are restructured through variations in the control parameters. Numerical calculations show the evolution of the boundaries of the attractors, the changes within simply-connected regions, etc. Some of the regularities could be identified in a physical experiment. Pis’ma Zh. Tekh. Fiz. 23, 40–46 (February 26, 1997)     

Photo-induced SHG as a sensitive tool for the detection of surface morphology for iron garnet derivative films deposited on GGG substrates

The influence of surface morphology on the photo-induced optical second harmonic generation (SHG) is established for specific iron garnet films deposited on (111) and (100) planes of the Gd₃Ga₅O₁₂ substrate, respectively. The anisotropy of the film surface is assigned to the substrate crystallographic plane used. It is shown that the decrease of the film's mean grain size enhances the output SHG signal. The increase of the mean grain size from 30 nm up to the 46 nm leads to a decrease of the photo-induced SHG (up to 30%). This could be used for the contactless diagnostic of garnet films' morphology.     

基于球形译码的分布式空频编码协同通信系统检测算法

针对频率选择性衰落下的多中继分布式空频编码协同通信系统,提出了一种基于球形译码的频域符号检测算法。理论分析和仿真结果表明,该检测算法不仅获得了与最大似然(ML)检测算法相同的误符号率性能,而且显著降低了分布式空频编码协同通信系统检测算法的复杂度,具有较高的实用价值。     

Chaos in a bistable chain of two unidirectionally coupled autooscillatory systems with time delay

We have studied the dynamics of a chain of two unidirectionally coupled delay-feedback autooscillatory systems possessing smooth asymmetric amplitude characteristics and the initial conditions of opposite signs, which result in the formation of two basins of attraction in the chain. The results of numerical simulations of the process of chaotization in a driven autooscillatory system and the transition of its oscillations to a state of forced synchronization with a change in the basin of attraction are presented. The mechanism of chaotization is considered.     

基于OGY的含间隙单级齿轮系统混沌运动控制

针对含齿侧间隙和轴承支承间隙的单级齿轮系统在部分参数区域内的混沌运动,用改进的OGY混沌控制原理实现了混沌吸引子内部不稳定周期轨道的稳定化。通过有限差分法替代非光滑点Jacobi矩阵实现光滑系统的OGY控制向非光滑多维系统转变,用伪不动点法(PNF)搜索混沌区域内不稳定周期伪不动点,根据动力学方程和变分形式,求解改进OGY算法中的Jacobi矩阵和敏感度列向量,结合Poincaré映射截面解析了混沌吸引子向多周期轨道转迁时的轨道间隔及迁移特性。仿真结果表明改进后的OGY控制法对高维非光滑齿轮系统混沌控制同样有效;多周期轨道持续控制时随目标周期轨道增加控制难度增大,所需参数摄动量相应增加。     

Precision synchronous polarimeter with linear response for the measurement of small rotation angles

A synchronous polarimeter was set up for the measurement of small rotation angles of the polarization plane of light. The polarimeter is based on a polarizer-Faraday modulator-analyzer structure with a synchronous detection scheme, which produces a linear system response. The theoretical background is studied, and the system performance is investigated experimentally. We achieved an accuracy of the order of 10(-4) deg, or 5 mg/dl of glucose in a 1-cm light path.     

Generator of chaotic microwave oscillations based on a high-power bipolar transistor

A chaotic microwave autooscillatory system has been designed, implemented on a high-power bipolar transistor (2T 982 A-2), and studied. The experiments showed stable generation of chaotic oscillations in a 5.26?C5.44 GHz range with a spectral power density of 1.3 × 10^?3 W/MHz.