混沌时间序列的局域高阶Volterra滤波器多步预测模型

依据相空间邻近轨道演化相似性特点建立训练模式,提出了基于自适应高阶非线性Volterra滤波器（HONFIR）的混沌时间序列多步预测模型（MSP-HONFIR）;通过定义距离相似度、趋势相似度来衡量轨道演化相似度,提出了混沌吸引子邻近轨道判别的新方法;从模型训练充分性角度出发探讨了MSP-HONFIR滤波器模型训练集规模控制的依据.数值研究表明MSP-HONFIR滤波器模型的多步预测性能优于原有HONFIR滤波器模型. 关键词： 混沌 非线性自适应预测 Volterra滤波器模型 训练模式     

关于非自治系统三类广义同步存在性的研究

研究了两个单向耦合的非自治系统三类广义同步的存在性.在响应系统的修正方程具有渐近稳定平衡点、渐近稳定周期轨道或渐近稳定拟周期轨道的情况下,满足一定的条件,可将广义同步化流形存在性问题转化为Lipschitz函数族的压缩不动点问题,并且理论证明了该广义同步化流形的指数吸引性.同时,以Duffing系统为例进行了数值仿真,其结果与理论推导相一致. 关键词： 广义同步化流形 压缩不动点 指数吸引性     

Hybrid method for investigation of electromagnetic scattering from conducting target above the randomly rough surface

A current based hybrid method (HM) is proposed which combines the method of moment (MOM) with the Kirchhoff approximation (KA) for the analysis of scattering interaction between a two-dimensional (2D) infinitely long conducting target with arbitrary cross section and a one-dimensional (1D) Gaussian rough surface. The electromagnetic scattering region in the HM is split into KA region and MOM region. The electric field integral equation (EFIE) in MOM region (target) is derived, the computational time of the HM depends mainly on the number of unknowns of the target. The bistatic scattering coefficient for the infinitely long cylinder above the rough surface with Gaussian roughness spectrum is calculated, and the numerical results are compared and verified with those obtained by the conventional MOM, which shows the high efficiency of the HM. Finally, the influence of the size, location of the target, the rms height and correlation length of the rough surface on the bistatic scattering coefficient with different polarizations is discussed in detail.     

LPCVD法制备的高纯半绝缘4H-SiC晶体ESR谱特性

利用电子自旋共振波谱（ESR）仪,分析由低压化学气相沉积（LPCVD）法制备的高纯半绝缘4H-SiC材料本征缺陷.结果发现,在暗场条件下获得的缺陷信息具有碳空位（V_C）及其络合物的特征;谱线具有半高宽较大、峰谷明显不对称的特点.分析认为造成ESR谱线半高宽较大及峰谷不对称现象的主要原因是测试温度较高.同时,吸收谱中峰谷不对称现象及较大半高宽现象的出现还与不对称的晶格结构及缺陷浓度的不均匀分布有关.在110 K测试温度下,能级上的电子分布对ESR谱特性影响很小. 关键词： 低压化学气相沉积 高纯半绝缘4H-SiC 电子自旋共振 本征缺陷     

A comparison of silicon oxide and nitride as host matrices on the photoluminescence from Er+ ions

This paper compares the properties of silicon oxide and nitride as host matrices for Er ions.Erbium-doped silicon nitride films were deposited by a plasma-enhanced chemical-vapour deposition system.After deposition,the films were implanted with Er3+ at different doses.Er-doped thermal grown silicon oxide films were prepared at the same time as references.Photoluminescence features of Er3+ were inspected systematically.It is found that silicon nitride films are suitable for high concentration doping and the thermal quenching effect is not severe.However,a very high annealing temperature up to 1200° C is needed to optically activate Er3+,which may be the main obstacle to impede the application of Er-doped silicon nitride.     

The constructive technique and its application in solving a nonlinear reaction diffusion equation

A mathematical technique based on the consideration of a nonlinear partial differential equation together with an additional condition in the form of an ordinary differential equation is employed to study a nonlinear reaction diffusion equation which describes a real process in physics and in chemistry. Several exact solutions for the equation are acquired under certain circumstances.     

Cu掺杂的AlN铁磁性和光学性质的第一性原理研究

采用基于密度泛函理论（DFT）的总体能量平面波超软赝势方法,结合广义梯度近似（GGA）,对Cu掺杂AlN 32原子超原胞体系进行了几何结构优化,计算了Cu掺杂AlN的晶格常数,能带结构,电子态密度和光学性质.结果表明,Cu掺杂AlN会产生自旋极化状态,能带结构显示半金属性质,掺杂后带隙变窄,长波吸收加强,能量损失明显减小.同传统的稀磁半导体（DMS）相比,Cu掺杂AlN不会有铁磁性沉淀物的问题,因为Cu本身不具有磁性.因而,Cu掺杂的AlN也许是一种非常有前途的稀磁半导体. 关键词： AlN 第一性原理 铁磁性 光学性质     

频谱分割波分复用无源光网络及色散影响

频谱分割是使用窄带光滤波器选择宽带光源光谱的一个切片的WDM技术,在波分复用无源光网络(WDM-PON)中采用波分复用器((MUX)进行频谱分割,能够实现光网络单元(ONU)的无色化.模型分析表明由于频谱分割的作用,使得波分复用器光通带外的频谱成分被过滤,减小了宽带光源的色散影响.在20 nm CWDM标准信道间隔下,能够以不超过1 dB的光功率代价支持155 Mb/s信号在20 km的G.652常规光纤上传输;在0.8 nm DWDM信道间隔下则能够支持2.5 Gb/s信号传输,色散引起的光功率代价低于0.5 dB.采用中心波长为1550 nm、谱宽70 nm、输出功率为-10 dBm的LED,研制了125 Mb/s速率信号直接调制的无色ONU.在信道间隔为20 nm、光纤长度为20 km的4波长WDM-PON系统上进行测试,色散等因素引起的光功率代价小于1 dB,系统光功率余量则超过5.6 dB.     

Novel image fusion method based on discrete fractional random transform

We introduce a new spectrum transform into the image fusion field and propose a novel fusion method based on discrete fractional random transform （DFRNT）. In DFRNT domain, high amplitude spectrum （HAS） and low amplitude spectrum （LAS） components carry different information of original images. For different fusion goals, different fusion rules can be adopted in HAS and LAS components, respectively. The proposed method is applied to fuse real multi-spectral （MS） and panchromatic （Pan） images. The fused image is observed to preserve both spectral information of MS and spatial information of Pan. Spectrum distribution of DFRNT is random and uniform, which guarantees that good information is reserved.     

应用ICP-AES法研究云南普洱茶稀土含量

应用电感耦合等离子体发射光谱法(ICP-AES)对云南省普洱茶主产地采集的150份普洱茶样品的稀土含量进行检测研究.检测样品中稀土的含量在0.26～4.07 mg·kg-1范围.依据国家标准GB 2762-2005<食品中污染物限量>中稀土限量标准2 mg·kg-1考核,43%的普洱茶样品被检出稀土含量超标.云南普洱熟茶和生茶不同的生产工艺会造成普洱茶稀土含量的差异,并影响产品质量.云南普洱茶不同主产地区之间的稀土含量存在差异,个别地区的普洱茶稀土质量安全控制情况不容乐观.