Synchronization of Chaotic Intensities and Phases in an Array of N Lasers

A linear array of N mutually coupled single-mode lasers is investigated. It is shown that the intensities of N lasers are chaotically synchronized when the coupling between lasers is relatively strong. The chaotic synchronization of intensities depends on the location of the lasers in the array. The chaotic synchronization appears between two outmost lasers, the second two outmost lasers, etc. There is no synchronization between nearest neighbors of the lasers. If the number of N is odd, the middle laser is never synchronized between any lasers. The chaotic synchronization of phases between nearest lasers in the array is examined by using the analytic signal and the Gaussian filter methods based on the peak of the power spectrum of the intensity. It can be seen that the message of chaotic intensity synchronization is conveyed through the phase synchronization.     

一类时变非线性振动系统的同步控制方法

对于一类非自治的非线性振动系统，设计了控制方法并建立了相应的派生系统，使得派生系统能与原系统达到同步.利用Lyapunov稳定性理论证明了两个系统在一定条件下可以达到同步，给出了耦合参数的选择条件.对于含参数激励与强迫激励的Mathieu方程以及拟周期激励的Duffing方程进行了实际的仿真计算，证明了派生系统可以与原系统的拟周期、混沌运动快速实现同步. 关键词： 派生系统 同步 差别方程     

Experimental determination of Representative Volume Element (RVE) size in woven composites

A systematic approach is proposed to estimate the length scales of the representative volume element (RVE) in orthogonal plain woven composites. The approach is based on experimental full-field deformation measurements at mesoscopic scales. Stereovision digital image correlation (DIC) is conducted to determine the full-field strain distribution in on- and off-axis specimens loaded axially in tension. A sensitivity analysis is carried out to optimize the image correlation parameters. Using the optimized set of image correlation parameters, full-field strains are measured and used in conjunction with a simple strain averaging algorithm to identify the length scales at which globally applied and spatially-averaged local strains converge in values. The size of a virtual window containing local strain data, the average of which has the same value as the global strain, is identified as the RVE dimensions for the examined material. The smallest RVE sizes found in this work are shown to be both strain and angle dependent. The largest RVE dimension obtained is reported as a unique, strain and orientation insensitive RVE size for the woven composite examined.     

Plasticity in polymeric honeycombs made by photo-polymerization and nozzle based 3D-printing

Study of the plastic deformation in polymeric honeycombs can pave the way for understanding the deformation localization in more complex cellular structures, which have received progressive attention in the past few years. This study compares the strain localization in deforming honeycombs made by two cost-effective 3D-printing technologies. Hexagonal honeycombs and their unit cell models were 3D-printed by both PolyJet™, using a photo-crosslinkable polymer, and fused deposition modeling (FDM) using a thermoplastic material. The state of the art digital image correlation (DIC) technique was employed as the experimental route in order to calculate the strain field during the deformation of manufactured parts. It was found that DIC is an effective tool to study the localization in 3D-printed honeycomb struts. Moreover, in comparison with FDM, PolyJet technology provides more homogeneous strain distributions in struts. In addition, FDM decreases the maximal strains generated on the side layers of the honeycomb struts. Accordingly, the ligament damage under plastic deformation can be postponed and the energy absorption capability of the product can be improved when PolyJet technology is utilized.     

ARINC659总线桥接的设计及对总线同步的影响分析

ARINC659总线因其在时间和空间上均提供了完备的故障冗余和操作健壮性,已经逐渐在对数据通信确定性及故障沉默和屏蔽要求较高的航天领域中展开应用。为了使ARINC659总线能够更好的适应航天器综合电子系统的高度冗余容及分布式控制的需求,对一种能够在不同设备中ARINC659总线之间相互桥接的技术进行了研究,进而实现分布式综合电子系统中所有硬件模块的统一时序规划和通信调度,可以显著提升系统中的资源共享、并行处理、故障冗余及分布式控制能力,同时也为关键系统中不同设备中的硬件模块间实现严格的时序关系操作提供了一种解决方案。最后就桥接对ARINC659总线同步机制的影响进行了分析,据此提出了桥接设计的约束和实现规则。     

Measuring and calculating geometrical parameters of marine plankton using digital laser holographic imaging

The purpose of this paper is to develop an approach using digital laser holographic imaging for measuring and calculating geometrical parameters of marine plankton. It is very important for study of marine plankton and it facilitates the analysis of marine plankton. Using this approach, we obtained geometrical parameters of marine plankton including perimeter, equivalent diameter, lateral size and so on. It is found that a measurement aberration is less than 8% for copepods sample by using collimating reference wave.     

GS-221高速摄影机的驱动与控制系统

GS—221高速摄影测量仪是用于测量大型火箭(导弹)起飞段的姿态及其横向漂移量的专用超小型高速电影经纬仪,其主机为一台间歇式同步高速电影摄影机。本文简要介绍其驱动控制和点阵数据记录系统。