How many parameters can be identified by adaptive synchronization in chaotic systems?

Five interesting experiments have been done for a class of chaos synchronization systems with unknown parameters and unknown control directions. And three important conclusions about parameters identification have been made. First, a necessary and sufficient condition for parameters identification is obtained. Second, a Nussbaum method is proposed to solve the problem of unknown control direction. Third, the adaptive method is not infinitely effective considered for our current ability of computation and simulation algorithm.     

基于特征级融合的多波段舰船目标识别方法

针对复杂情况下海上舰船目标单波段特征识别能力不足的问题,研究可见光、中波红外和长波红外三波段特征图像融合技术,重点解决图像融合方法中存在的算法耗时和融合策略选择的问题,提出了一种新的基于区域协方差矩阵的多波段特征级融合方法,针对可见光图像和红外图像分别设计11维和5维特征向量,协方差矩阵可以将多个特征进行融合,既保证了不同目标之间的区别性,同时又减小计算量。该方法首先利用显著性检测,快速定位图像中的目标区域,然后,针对不同波段图像设计的特征向量定义协方差阵的距离计算公式并进行匹配,通过对图像的一次遍历操作获得积分图像,在协方差计算时达到快速计算的目的,最后利用k-阶最近邻算法对多种舰船目标进行分类识别。利用实拍的3 400余张三波段舰船目标图像作为测试数据。实验主要分为两部分,首先对比单波段和三波段融合识别的识别率,验证所提出的融合方法具有更广的应用范围;然后,在计算效率上对比多种传统的像素级方法,验证采用的特征级融合在计算时间上的优势。实验结果表明,该方法可达到95.1%的识别率,单帧计算耗时约为0.5 s,在实时性和检测率方面都有明显提高。     

High-Gain Nanosecond Vortex Laser

We demonstrate a high-gain vortex power amplifier with the double-pass configuration based on the rod Nd:YAG crystal. In the experiments, a nanosecond vortex seed beam is converted from a conventional Q-switched Nd:YAG laser output with a spiral phase plate and then amplified with the Nd:YAG amplifier stage. A maximum amplification output energy up to 163.5 mJ is achieved at 20 Hz with a 3.2-ns pulse, corresponding to an amplification factor of 81.8. Further discussions are provided to find ways of increasing the power scaling.     

氨水团簇H2O（NH3）n（n=1-6）结构的密度泛函理论研究

用密度泛函理论（DFT）的B3LYP方法,对氨水团簇氢键体系H2O（NH_3）n（n=1-6）进行了研究,计算得到了氨水团簇H2O（NH3）n（n=1-6）的各种稳定构型,并对氨水团簇的结构特点做了进一步分析。最后利用二阶差分理论讨论了不同尺寸氨水团簇的生长规律。     

Screening benzylpentazoles for replacing PhN5 as cyclo-N5 − precursor by theoretical calculation

Structural Chemistry - Benzylpentazole (B) and its derivatives (B-NH 2  ~ B-NF 2 ) with electron-donating group (?NH2, ?NHMe, ?NMe2, and?OH) and...     

Dynamical properties of discrete Lotka–Volterra equations

A discrete version of the Lotka–Volterra differential equations for competing population species is analyzed in detail in much the same way as the discrete form of the logistic equation has been investigated as a source of bifurcation phenomena and chaotic dynamics. It is found that in addition to the logistic dynamics – ranging from very simple to manifestly chaotic regimes in terms of governing parameters – the discrete Lotka–Volterra equations exhibit their own brands of bifurcation and chaos that are essentially two-dimensional in nature. In particular, it is shown that the system exhibits “twisted horseshoe” dynamics associated with a strange invariant set for certain parameter ranges.     

General principles for designing mode converters based on air-hole collapse in photonic crystal fibers

The general principles for designing mode converters based on air-hole collapse in photonic crystal fibers (PCFs) are theoretically investigated in this paper. The splice-like point in mode converters is found unnecessary for mode conversion; however, two different and separated cores, the adiabatic transitional part and the final merged core, are essential. Three structures are investigated using logical deduction, and the numerical results agree well with the logical conclusions.     

Existence and global exponential stability of almost periodic solution for CNNs with variable coefficients and delays

By using exponential dichotomy and the Banach fixed-point theory and combining Yang inequality, some sufficient conditions are derived ensuring existence and global exponential stability of almost periodic solution for CNNs with variable coefficients and delays. Without assuming the boundedness of signal function, these results obtained here can be expected to have highly important significance in designs and applications of the networks. We extend and improve previously known results.